ATAS DO SIMPOSIO

SÔBRE A

BIOTA AMAZÔNICA

VOL. 3: LIMNOLOGIA

Belém, Pará, Brasil, Junho 6-11, 1966

EDITOR: HERMAN LENT

Publicado pelo

CONSELHO NACIONAL DE PESQUISAS

RIO DE JANEIRO, GB

1967

APRESENTAÇÃO

De 6 a 11 de junho de 1966, na cidade de Belém, Estado do Pará,

Brasil, foi realizado o Simpósio sôbre a Biota Amazônica, organizado

pela Associação de Biologia Tropical, com a colaboração do Conselho

Nacional de Pesquisas do Brasil, tendo José Cândido de Melo Carvalho

como Presidente Executivo.

O Simpósio homenageava especialmente o Museu Paraense “Emí-

lio Goeldi” que comemorava seu 100. 0 aniversário.

Ao se iniciarem os trabalhos, achavam-se inscritos no Simpósio 16

países representados por 97 instituições, 256 pesquisadores irtscritos

para apresentação de trabalhos que perfaziam um total de 22 confe-

rências e 198 contribuições originais. Associaram-se como observadores,

até êsse dia, 103 pessoas. Nos dias que se seguiram, até o encerramento,

o total geral de frequência dos inscritos foi a 611 pessoas. As contribui-

ções originais também aumentaram para 227.

Resolvemos editar estas Atas em 7 volumes, cada qual correspon-

dendo a uma das seções do Simpósito: Geociências, Antropologia, Lim-

nologia, Botânica, Zoologia, Patologia e Conservação da Natureza e

Recursos Naturais; serão todos publicados pelo Conselho Nacional de

Pesquisas do Brasil, que assumiu a responsabilidade global da edição,

da mesma forma como promoveu a realização e apoiou a execução do

Simpósio.

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Em relação ao Programa do Simpósio distribuído na ocasião e,

ainda, ao próprio desenrolar das reuniões de cada Seção, as Atas não

incluem necessàriamente todos os trabalhos, retirados que foram al-

guns por motivos vários.

Êste terceiro volume corresponde à Seção III (Limnologia) que teve

como coordenador Harald Sioli (Max-Planck-Gesellschaft, Plón); consta

de um total de 226 páginas, 60 figuras no texto e 4 encartes, e divulga

17 trabalhos, dos quais duas conferências. O índice do volume aparece

a seguir pela ordem alfabética do sobrenome dos autores, primeiro as

conferências e depois as comunicações.

Herman Lent

Julho, 1967

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Pag.

Leentvaar, P.

The artificial Brokopondo Lake of the Suriname river. Its biolo-

gical implications 127

Medem, Federico

El género Paleosuchus en Amazônia 141

Oltman, Roy E.

Reconnaissance investigations of the discharge and water quality

of the Amazon 163

Paraense, W. Lobato

Moluscos Planorbídeos da Amazônia 187

Sattler, Werner

Primeiros resultados de pesquisas etológicas em invertebrados

límnicos da Amazônia 195

Schwassmann, Horst O.

Orientation of Amazonian fishes to the equatorial sun 201

Ungemach, Harald

Sôbre o balanço metabólico de iônios inorgânicos da área do sis-

tema do rio Negro 221

1, | SciELO

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 1-7 — 1967

HYDROBIOLOGY IN THE AMAZON REGION

G. MARLIER

Institut Royal des Sciences Naturelles, Brussels, Belgique

The Amazon watershed is the

greatest river basin of the tropical

world. It has an extension of 6,5

million square kilometers (i.e. 2,5

millions square miles). Its water

flow is the highest in the world

and has been computed by Katzer

to be near 120,000 cubic meters per

second at the mouth during the

dry season.

A look on the hydrographical

map edited by the Brazilian Insti-

tute of Geography (1953) shows

clearly the importance of the river

network on the structure of the

Amazonian region. But the best

way to visualize the part played by

water in the Amazonian environ-

ment, is to fly by Catalina plane

over the river from Belém to Ma-

naus. Then the interdependence of

soil and water appears without a

doubt.

The history of this watershed

has been told many times and Pro-

fessor Sioli recently gave a sum-

mary of the succession of geologi-

1 — 37 121

cal events which led to the shape

of the country we presently know.

The actual fluvial basin is the

remain of the huge freshwater lake

which extended over the whole

“planície” above the region of Óbi-

dos, during the second half of the

Tertiary and the first part of the

Pleistocene. This lacustrine stage

thus lasted a comparatively short

time and the present river network

lasted still less.

The geographical conditions of

the Amazon plain bring about some

important consequences, from

the viewpoints of Limnology and

Biology. One of these is the great

extension of the brackish waters in

the mouth of the river itself and

also on the coast of the Ocean. This

has formed an almost ideal start-

ing point for the invasion of the

freshwaters of the region by sea

animais.

The most conspicuous of these

are the Cetaceans. Two species of

Dolphins have adapted themselves

completely to freshwater condi-

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tions in the Amazon; they are the

great “pink” dolphin, or Boto, Inia

geoffroyensis (Blainville) and the

lesser grey dolphin or Tucuxi, So-

talia pallida (Gervais) .

Other very typical sea animais

are the shark, the saw-fish and

some stingrays, of which the first

two are probably marine individ-

uais making migration far into

the river (as far as Manaus and

Iquitos) while the rays are certain-

ly wholly adapted to a freshwater

life.

Among the bone-fishes also some

marine families are now com-

pletely at home in the Amazonian

freshwaters such as the Needle-

fishes, the Soles etc.

These marine families have also

representatives in some other

fresh-waters, particularly in the

Tropics, but we think that no-

where such an array of marine ani-

mais found their way in a fresh-

water fauna in which a rich true

freshwater fauna also exists. (We

must not forget the presence of a

shark in lake Nicarágua, of Dol-

phins in índia and China, of sting-

rays in the freshwaters of several

tropical countries).

Among the Invertebrates of ma-

rine origin, we may mention the

Nemertine Siolineus turbidus Ev.

du Bois Reymond, found by Prof.

Sioli in the Tapajós and which be-

longs to the Order Heteronemerti-

na. As the other freshwater Hete-

ronemertines “Nemertes” polyho-

pla and Planolineus exsul, found

respectively in lake Nicarágua and

in the Botanical garden of Buiten-

zorg, Sliolineus shows strong ma-

rine affinities and its presence in

the Tapajós points to a recent evo-

lution of this species from a for-

merly marine environment. An-

other interesting worm of recent

marine origin is the Polychaete

Lycastis siolii Diniz Corrêa found

by the same collector in the Ta-

pajós. This species must be,

according to Corrêa (1948) not an

old marine relict, but a “young”

marine immigrant.

As the knowledge of the fresh-

water fauna is still in its infancy,

it is likely that many more instan-

ces of such marine invasions will

be found in the future. Very dif-

ferent conditions prevail for in-

stance in África where most of the

continent is high above sea levei

and where marine migrants do not

enter the freshwaters very far in-

land.

Another geographical condition

of great importance and having

both direct and indirect conse-

quences, is the very small slope of

the Amazon and its great affluents

and the very flat nature of the ba-

sin. The river itself has a slope of

1/100,000. But as the rainfall is

very high and seasonal in the high-

est reaches of the Amazon, proper

and its affluents, the levei fluc-

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Volume 3 (Limnologia)

tuations are very powerful (They

may reach 15 meters annually in

Manaus on the lower Rio Negro) .

At high water time, the waters

of the Amazon and of its big af-

fluents flow over the banks and

flood the neighbouring land, enter-

ing the forests and backing up the

waters of the minor affluents .

These, in turn, swell and enter the

surrounding country. This huge

inundation area is thus accessible

to the river animais which invade

the formerly terrestrial environ-

ments where they feed and proba-

bly spawn. This explains how fish

can find very favourable life con-

ditions during the high water

times. We know that this occurs

also in several other tropical re-

gions as in the African big rivers

(principally the Niger and the

Nile) and in the South Asian sub-

continent when the Mekong shows

very important levei fluctuations .

But all these countries are very

much more populated and deforest-

ed in such a manner that fish

doesn’t find as favourable feeding

grounds as in the huge Amazonian

forest .

This third geographical feature

of biological importance is the

absence of old lakes in the Amazo-

nian plain. All the hitherto known

amazonian lakes belong to one or

two types, both of which are shal-

low and very young.

The first type is the “varzea la-

ke” which is a lake in continuous

or periodical relation with the

Amazon or with a white water af-

fiuent and receives water from

these rivers either by a permanent

“furo” or by the periodical inva-

sion of its effluent at high water

time.

The second of these types is the

“terra firme” lake which flows into

the Amazon by a long effluent. It

may swell into a large lake when

its effluent is dammed by the high

waters of the Amazon but it never

receives white waters from the

latter.

Both types of lakes are thus very

dependent of the river itself and

it is thus not surprising that no

real lake fauna could be evolved in

them, comparable with the parti-

cular lake fauna of África, for in-

stance.

The fishes of these lakes are

those of the rivers, or may be a lit-

tle less numerous. But these lakes

are very important spawning

grounds for many of the river fish-

es most of which have migratory

habits. These fish migrations in the

amazonian waters are well known

(the piracema) and are probably

obligatory for the success of repro-

duction of most species (as it is

for most Indian Carps in the Asian

Continent). If this is confirmed,

the scarcity of lake and pond spe-

cies able to spawn in confined con-

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Atas do Simpósio sôbre a Biota Amazônica

ditions may be an obstacle to the

use of Amazonian fishes for fish

culture.

In fact one could think that af-

ter the lapse of thousands of years,

or after tectonic movements take

place, the Amazonian region will

be very rich in lakes, as so many

deep drowned valleys are known

to exist in this basin. We know,

personally, no lake out of reach of

the rise of the Amazon or its af-

fluents and which could have an

independent existence from that

of the rivers.

The orographic conditions of the

basin have another result. No true

lakes, with the classical characters

of the deep lakes, can be found.

From the theoretical considera-

tions developed by Lõffler, we

should expect that a deep lake in

this equatorial forest of climate Af

and Am would be oligomictic; it

means that it would mix and cir-

culate at irregular intervals, owing

to the great stability due to the

high water temperature.

In fact most of the lakes studied

by Braun and the author were of

the polymictic type, being too

shallow to develop a great stability.

Of course this limnological condi-

tion has very important conse-

quences on the nature of the

fauna.

Apart from its freshwater fauna

directly from marine origin, the

Amazonian freshwaters harbour an

extraordinary rich freshwater fau-

na. It is yet not well known, except

for some particular groups and we

may suppose a great number of

species remain to be found.

Let us consider the class of

Fishes to which many studies have

been devoted. It is well known that

a great part of the aquarium fishes

are of south american and parti-

cularly amazonian origin. More

than 1500 species of fish have been

described from the area, a respec-

table number considering that it

belongs to one watershed only. If

we compare it with other fresh-

waters in the Tropical regions, we

see that the river Congo harbours

a little more than 500 species (not

included the fauna of Lake Tan-

ganyika), the Ganges 300, the

Nile 200 etc.

South America has been isolated

from North America during the

greater part of the Tertiary period

and was United with the latter

Continent only in the Pliocene. Its

freshwater fish fauna is very much

endemic, owing to this long isola-

tion and we find that many fish

families are peculiar to South

America, and have found in the

huge Amazonian tertiary lake and

the subsequent water network an

ideal distribution area. Such are

the Gymnotids, many Siluroid fa-

milies and the greater part of the

Characids.

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Volume 3 (Limnologia)

From the point of view of the

Chemical and physical conditions,

the amazonian waters represent,

as is well known, one of the follow-

ing three types. The “white” wa-

ters rivers are loaded with a rather

great quantity of silt, which they

collect in the Crossing of the Andes.

Such are the Amazon proper, the

Madeira; compared with other

amazonian rivers these waters are

relatively rich in salts. This assess-

ment is, of course, to be taken

with some caution.

According to Sioli, the total

hardness (expressed in German

degrees) of the Amazon around

Santarém, varies between 0.65 and

1.27. This compares very well

with the hardness of river Congo

near Stanleyville, which is around

1 . 4 but is well below that of the

river Nile at Cairo, which reaches

5.0.

The second type are the “clear”

water rivers, coming from much

older ranges which are the central

brazilian plateau and the Guyana

plateau. These do not give rise to

great mineral transport and very

scon these rivers loose their load

and carry only crystal-clear waters

(river Tapajós). These contain va-

riable quantities of dissolved salts

but generally lower quantities

than the white waters (according

to Sioli the Tapajós has a total

hardness of 0.31 to 0.82, German

degrees) . Their pH is also general-

ly low when the rivers do not cross

geological deposits particularly

rich in calcareous salts as are the

Carboniferous layers of the Middle

Tapajós.

As the anorganic nutrient con-

tent of all waters flowing in the

Tertiary layers of the Série das

Barreiras is always very low and

as the limestone rich layers of the

Carboniferous period are of a re-

duced extension we may safely as-

sume that the principal source of

dissolved nutrients is the Andean

and Subandean region where the

Amazon proper and some large

white-water affluents have their

headwaters.

The “black “waters have a brown

colour given to them by the leach-

ing of the humic soils in the fo-

rest swamps called Igapos. These

waters are generally rather trans-

parent, very poor in salt and of a

very low pH (4.4 and even less) .

From the biological point of

view, we must point here to the

influence of these Chemical pro-

perties of the waters on their fau-

na. As an instance we find many

fish species in the black water ri-

vers, even if they are less nume-

rous than the white waters species.

But it is generally admitted that

such low pH values around 4 would

preclude even the existence of

fishes.

Indeed it is difficult to under-

stand how the hemoglobin of these

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Atas do Simpósio sôbre a Biota Amazônica

animais can be saturated with oxy-

gen in the presence of such acidic

waters and how the blood can get

rid of its dissolved C0 2 . Anyway

it seems, according to the expe-

riences of Willmer, that the ef-

fects of water acidity are less pro-

nounced in warm than in cold wa-

ter fishes.

A last characteristic of the Ama-

zon rivers is to be found in the cy-

cle of production of plankton in

the lakes formed on the banks

on in the course of the affluents

of the river.

It has been found by the author

that the primary productivity in

the waters of the white water lakes

may undergo an annual cycle

according to the fluctuations of the

lake levei and its relations with the

Amazon. It is, of course, easy to

understand knowing the relative

riches of these white waters, that

their invasion in the lakes may

bring about a renewal of the

nutrient resources of the environ-

ment. This renewal is followed by

an increase of the phytoplankton

standing crop.

We thus arrive at the conclusion

that one of the most important

of the factors in the amazonian en-

vironment is related to fluctua-

tions of the white waters and the

penetration of these waters in the

lakes. Knowing this, we under-

stand how imperative it is for the

limnologist and the fishery expert

to have a good hypsometric survey

of the Amazonian basin with the

contour lines very close to each

other.

It has been said above that nu-

trients brought by the waters are

always rather scarce but this

seems in disagreement with the

great wealth of the fauna one finds

in the Amazon basin. This appa-

rent paradox is explained when

studying the alimentary regimes of

the fish of the rivers and lakes.

These fishes are found to feed

frequently on items which are de-

rived not from the aquatic biolog-

ical cycle but from the terrestrial

environment of these waters, i.e.

from the shore forest. Many spe-

cies feed directly on leaves, seeds,

fruits or on terrestrial insects or

other invertebrates which take

their subsistence in the riparian

vegetation. It is thus the forest

which maintains the fish fauna at

its present high levei. AU altera-

tions to this Uttoral forest could

mean the disappearance of most

fishes and of a valuable food re-

source for the human population.

This points to the necessity of

respecting the littoral forest while

planning development and agri-

cultural schemes in Amazônia, con-

sidering the Hylaea as a most

valuable element even in the aqua-

tic resources of the country. Any

attempt to fell and burn the forest

without due care to replace the

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10 11 12 13 14 15 16

Volume 3 (Limnologia)

burned or exported nutrients

would mean a loss of productivity

in the waters.

SELECTED BIBLIOGRAPHY

Du Bois Reymond Marcus, E., 1948,

Siolineus, a new Heteronemertine.

Boi. Fac. Fil. Cien. Letr. Univ. S.

Paulo, Zool., 13:

Corrêa Diniz, D., 1948, A Polychaete

from the Amazon Region. Boi. Fac.

Fil. Cien. Letr. Univ. S. Paulo, Zool.,

13: 245-257.

Katzer, Fr., 1903, Grundzüge ãer Geo-

logie des unteren Amazonas gebie-

tes. Max Weg., Leipzig.

Lõffler, H., 1957, Die klimatische

Typen des holomiktischen Sees.

Mitt. Geog. Ges. Wien, 99: 33-44.

Marlier, G„ 1966, Etudes sur les lacs de

rAmazonie Centrale. I. Cadernos

da Amazônia 5:

Myers, G. S., 1960, Notes and Com-

ments on: G. Fryer’s Fish Evolu-

tion in Lake Nyasa. Evolution, 14:

394-396.

Sioli, H., 1964, General features of the

Limnology of Amazônia. Verh. Int.

Ver. Limnol., 15: 1053-1058.

Sioli, H. & Klinge, H., 1962, Solos, tipos

de vegetação e águas na Amazônia.

Boi. Mus. Paraense Emílio Goelãi,

n. s„ 1: 27-41.

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Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 9-50 — 1967

STUDIES IN AMAZONIAN WATERS

HARALD SIOLI

Hydrobiologische Anstalt der Max-Planck-Gesellschaft,

Plõn (Holstein) , Western Germany

(With 10 text-figures)

As no other country, no other

landscape in the world, the Ama-

zonian region is formed and char-

acterized by its amount of waters.

The Amazon is not only the might-

iest river on earth, but also the fi-

nal collector of the largest net-

work formed by innumerable

creeks, rivers and streams, which

drain an area of about 7 million

square kilometers situated in a

very wet climate and covered by

the most extensive, continuous,

tropical rain-forest.

Thus it is no wonder that the

history of the studies of the Ama-

zonian waters starts with the his-

tory of the discovery and conquest

of the whole country of Amazônia

itself, that its very beginning coin-

cides with the first expeditions of

the Spanish and Portuguese dis-

coverers and “conquistadores”.

While Marco Polo travelled on

foot or on animais back on ancient

roads and paths to the fabulous

Middle Kingdom, while the Boers

penetrated South África, and

while pioneering settlers of North

America made their way to the Far

West, both on their four-wheel-

cars of the traditional stile of Cen-

tral — and Northwestern Europe,

while Sibéria was conquered by the

mounted Cossack posses, while

Arabs crossed Arabia, the Sahara

and the Near East on camel-cara-

vans, while the great discoverers

of Central África made their “Sa-

faris” with a more or less numerous

train of barefooted negro-carriers

— the Amazonian region was dis-

covered, opened and conquered

for Christian-European coloniza-

tion and civilization, from the late

Middle Ages up to recent times, by

expeditions and travellers, who

used the long and numerous wa-

terways as the only practicable

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10

Atas do Simpósio sôbre a Biota Amazônica

possibility to penetrate the endless,

dense jungle.

By this way, the waters of Ama-

zônia were the first of the factors

which ccmpose the Amazonian

landscape and with which the pio-

neers came into contact, and the

knowledge of the water-courses

was a conditio-sine-qua-non for

success of any colonization scheme.

The history begins with the

strange adventure of Don Francis-

co de Orellana, who, in February

1541, started from Quito, in the

high Andes, with an expedition,

lead by Gonçalo Pizarro, in search

of the land of “El Dorado” and of

cinnamon. With 4000 Indians and

220 Spaniards they went eastward,

down the mountains to the moist

and warm lowlands of the un-

known land. But they found

neither El Dorado, the legendary

gilded king in the silvery town of

Manoa, nor the cinnamon-trees .

Instead, the expedition ran short

of food and got into extreme emer-

gency. Pizarro and Orellana sepa-

rated, and the latter, driven by

famine, continued with his men in

eastern direction in vain search for

food. On the banks of the “Rio de

los Omáguas”, now Rio Napo, on

its confluence with the Rio Aguá-

rico, he ordered to build a boat, a

“bergantim”, for still exploring

some stretches down the river. By

the end of 1541, Capitán Francisco

de Orellana embarked in it toge-

ther with 55 Spanish soldiers and

two fratres, one of them being Frey

Gaspar de Carvajal, who became

the chronicler of the voyage.

They went down that river, hop-

ing to come back within a few

days. But also there they could not

find anything to eat, and the only

possibility that remained for Orel-

lana and his weakened men was to

continue the voyage on boax - d of

that boat, down the river with the

current which somewhere was to

flow into the ocean. And Orellana

decided to do so.

So there began one of the most

adventurous and remarkable voy-

ages ever made by man which led

to the discovery of that enormous

river which at first, received the

name of “Rio de Orellana”.

Frey Gaspar de Carvajal wrote

down what happened during the

trip, but he was a typical child of

his time and a representant of his

profession. He reported what hap-

pened on board, what the Spa-

niards did and how they suffered

and invoked the Holy Virgin etc.,

but practically nothing stands in

his narrative concerning the cha-

racteristics of the river or the land-

scape. He always describes more

and more only the hunger, the at-

tacks on Indian villages which be-

came less rare and finally very nu-

merous as they descended the ri-

ver, and where they killed the In-

dians who did not achiev to flee.

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Volume 3 (Limnologia)

11

and how they burnt the houses of

them. Is it a wonder that the na-

tives got more and more hostile,

the more the discoverers came

down the river? The communica-

tion-system of the Indians, consist-

ing of messangers and bush-

drums, had the fame of robbers

and killers go ahead of the des-

perate Spaniards . . .

Only the report on the discovery

of the Rio Negro, in the eve of

St. Trinity of 1542, written by Frey

Gaspar de Carvajal, is worth read-

ing for us. He wrote: “On the sa-

me day, starting from there and

continuing our voyage, we saw the

mouth of another big river, on the

left side, which entered that one

in which we navigated, and of wa-

ter as black as ink, and therefore

we gave to it the name of Rio Ne-

gro. It ran so much and with such

ferocity that for more than 20 lé-

guas (110 km) it made a strip in

the other water without mixing

itself with that one.”

These are the laconic words by

which, for the first time in history,

the biggest tropical black-water-ri-

ver has been made known to Eu-

ropean civilization.

The voyage of Orellana and his

men turned more and more a flight

down the river, a flight from hun-

ger and the hostile Indians. Final-

ly, on August 26th, 1542, the

mouth of the Amazon was reached.

Frey Gaspar de Carvajal writes:

“We came out of the mouth of that

river between two islands, separat-

ed from each other by 4 léguas

(22 km) of width of the river, and

the whole, as we have seen above,

has from one side to the other more

than 50 léguas (275 km) , while the

fresh water enters into the sea

more than 25 léguas (137,5 km).

The tides grow and fali 6 to 7 bra-

ças (10 — 11 1/2 m).”

The greatest river of the world

was discovered — strange to see,

from its headwaters at the feet of

the Andes to the ocean. But almost

nothing about it had been observ-

ed but its colossity, its shores which

were inhabited by very nume-

rous “savages”, and the existence

of some affluents, one of them

with remarkably black water.

It took some time, till the voy-

age made by Francisco de Orella-

na, was followed by the next ex-

pedition which shall only be

touched.

Pedro de Orsua started from

Cuzco in 1560 and descended the

Rio Yutaí into the Yuruá, and

from this river at 5 o S into the

Amazon. But not even a report of

this voyage has been left.

Much later on ; Juan de Palácios

came from Quito down the Rio Na-

po, but he reached only the “Pro-

víncia de los Encabelados” where

he was killed by the natives.

Only in 1636, i.e. almost 100

years after Francisco de Orellana,

cm

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10 11 12 13 14 15 16

12

Atas do Simpósio sôbre a Biota Amazônica

there started, from Quito, two

priests together with 6 soldiers on

the next voyage. They succeeded

in repeating the achievements of

the discoverer and finally reached

Grão Pará, where the Portuguese

had already a fortified “praça”,

which in the following time, de-

veloped to what is now the city of

Belém.

This voyage gave rise to the fa-

mous expedition of Pedro Teixeira,

a Portuguese general in Grão Pará,

in 1637-38, who was the first to as-

cend the river from Belém to Quito

and then return the same way.

At that time, the lower Amazon

up to the Tapajós had already been

well known, not only to the Portu-

guese, but also to the Dutch and

the British, who had started to

build fortresses and to occupy

parts of the country. Pedro Teixei-

ra had already fought those intru-

ders and gone up the Amazon and

the Tapajós for punishing the na-

tives and catching slaves. By such

experiences, he was well prepared

for that great, new enterprise for

which he took with him a total of

around 2000 persons in 47 canoas

“of good size”.

There exist two reports on that

expedition, the one by Alonso de

Rojas, the other one by P. Cristo-

bal de Acuna S. J., which are in

part identical, in part complete

each other mutually. Father Cris-

tobal de Acuna had been ordered,

by the Vice-Rey dei Peru to accom-

pany Pedro Teixeira on his way

back to Pará, while Alonso de Ro-

jas seems not to have participat-

ed in the expedition. The most vi-

sible result for our interests —

which do not coincide with the po-

litical aims of that expedition —

is the first map of the Amazon,

idealized and, probably, designed

by the pilot of Pedro Teixeira’s

fleet.

But not only that first map is

worthy of note for us, the reports

contain so many excellent observa-

tions of peculiarities of our oig ri-

ver and its surrounding landscape

— naturally also mistakes — that

for reasons, I shall explain after-

wards, it seems to me worth while

dedicating more time to them and

to cite some parts in extenso.

It is already another spirit, dif-

ferent from that of Frey Gaspar de

Carvajal, when Father Cristobal

de Acuna writes in his preface that

they arrived in Pará, on December

12th, 1639 “after having transpass-

ed the mountains which feed the

beginning of the great river, and

having travelled on its waves till

the mouth of 80 léguas (440 km)

width, after having written down

with special care all what is no-

table, after having determined its

height and annotated the names of

the affluents, having verified the

peoples who live on the banks, seen

the fertility and admired the re-

Volume 3 (Limnologia)

13

sources, having experienced the

climate, come into contact with

the natives and, finally, after not

having neglected what all there

happened and of what they had

been witnesses.”

We may say that, with the chro-

niclers of Pedro Teixeira’s voyage,

there began the exact and objecti-

ve observation, the study in a mo-

dem sense, of Amazónia.

Cristobal de Acuna soon starts

to discuss the origin of the Ama-

zon: “Some people want the Ma-

ranon as source with its beginning

in the Cordilleras de Guanuco de

los Caballeros, 70 léguas (385 km)

from the “Ciudad de los reys”, with

the lake Lauricocha; other ones

want the sources of the Rio Macoá

and with them the Caquetá as its

origin.” But this is rejected by Fa-

ther Acuna, and he means that in

a distance of 8 léguas (44 km)

from Quito, between the moun-

tains Guamamá and Pulca, there

are two lakes, 20’ below the equa-

tor-line, from which, in direction

to the south, the Amazon has its

origin.

According to him, the length

from the spring to the mouth into

the sea is 1356 léguas castelha-

nas (7458 km) , “well measured”.

Running in wide curves, the ampli-

tude and width are very different

from 1 — 2 léguas (5,5 — 11 km)

and partly much more, to 80 lé-

guas (440 km) in the mouth. The

narrowest place has a little more

than 1/4 léguas (1,4 km), at

2 2/3° S and 360 léguas (1980 km)

from the “lake” (what probably

must be taken for the sea). —

From the mouth to the Rio Negro,

in a distance of almost 600 léguas

(3300 km) , the main channel is

always at least 30 — 40 braças

(50 — 65 m) deep; at some places

one does not find any ground. Abo-

ve the Rio Negro the depth varies

among 20, 12, well above 8 braças

(35; 20; 13 m), but it is always

deep enough for boats. There are

innumerous islands, commonly of

4 — 5 léguas (22 — 28 km) , other

ones of 10 and 20 léguas (55 and

110 km) etc., and there are also

many very small ones, which serve

the natives for the plantations

while on the larger ones, they have

their settlings. “These small ones,

sometimes also the greater islands

or a great part of them are inun-

dated every year by the river which

fertilizes them in this way with its

mud so that they can never be call-

ed sterile even if there is claimed

from them the same production of

corn and mandioca in many sub-

sequent years.”

There are many fishes “which

the natives catch with incredible

abundance every day in the river.

King of all fishes, however, and by

which the whole river from the

source to the mouth is inhabited,

is the “Peixe boi” (“ox-fish”),

14

Atas do Simpósio sôbre a Biota Amazônica

which has only the name of a fish,

for there is nobody who, eating it,

does not think it to be real meat.

It is of the same size like a 1 1/2

years old calf and, if it had horns

and ears, its head would not differ

from a calf’s one. Its whole body

is covered with rather short hairs

like soft bristles, and it moves in

the water with two short arms,

which, looking like shovels, serve

it for sculls. Under these “arms”

the female has its teats, which it

gives to the young ones, it has

born. The warriors make so strong

shields of the very thick leather

that, if the leather is well curried,

no bullet can perforate them. This

fish lives only on herbs, which it

grazes like a real ox, and thus its

meat gets so highly nutritious and

has such a good taste that a man

becomes more satisfied and strong-

er by a small amount of it than

by double the quantity of goat-

meat. It cannot stay under water

for a long time, and so it lifts its

snout out of the water for taking

breath, wherever it is swimming.

And thus this fish promotes its to-

tal extermination, because it ena-

bles its own enemy to find it very

quickly; the Indians become aware

of the animal and follow it in

small canoes, waiting that it will

lift its head out of the water, in

order to draw a deap breath, and

then they kill it with their har-

poons which they make of muss-

els.”

This description of the manati is

very exact, and till Alfred Russel

Wallace, who, in 1848 — 1852 made

a voyage on the Amazon and the

Rio Negro, there was nobody to

excel it.

The number of water-turtles

must have been enormous at that

time: “They (the Indians) catch

these turtles in such a quantity

that there is not even one of those

fences” (in which the Indians store

the turtles alive) “which would

not contain turtles in a number

from 100 upward”.

Acuna describes also Indian fish-

ing methods, as fishing with tim-

bó, or harpooning with arrows,

equipped with a swimmer, which

they throw with their hands. In-

teresting is his description of the

electric eel: “Many fishes have spe-

cial pecularities, e, g. one, the In-

dians call Peraque, has the shape

of an enormous eel or better of a

small Conger. And the one who

touches this fish, begins to tremble

all over like attacked by shivers of

Malaria, and it lasts as long as

there is a contact between the fish

and this person, stopping immedia-

tely when loosing the fish.”

Naturally, since it was one of

the main interests of his time,

Acuna speaks of enormous riches

in gold, “for all rivers and springs

etc., which run from the Andes to

Volume 3 (Limnologia)

15

the Amazon at a stretch of 600 lé-

guas (3300 km), come from areas

which are the richest in silver and

gold on earth.”

After him, the climate is “tem-

perate”, and the winter is not caus-

ed by changes in the position of

the planets and the sun, which ri-

ses and sets always at the same

hour, but by floods which impede

agriculture and the harvesting of

fruits of the earth for some

months. There are no “rotten airs”,

and “if there were no plagues of

mosquitos which in many zones are

so innumerous, one could call the

river at the top of one’s voice an

enlarged paradise.”

In his narrative he gives a cir-

cumference of 4000 léguas

(22000 km) to the whole Amazon

Region, and his report contains

many details about the affluents

of the Amazon, and the Rio Negro

called his great interest. At the

mouth it is 1 1/2 léguas wide

(8,25 km) . Its black water fills half

the width of the bed of the Ama-

zon and accompanies it for more

than 12 léguas (66 km) where one

can clearly distinguish between the

water of the Amazon and the one

of the Rio Negro, till it is mixed

up into the turbid water of the

Amazon. Here we also find the first

mention of the connexion with the

Orinoco, the famous anastomose

through the Cassiquiare: “One

arm which that river” (the Rio Ne-

gro) “sends out through which,

after informations, one comes out

in the Rio Grande in the mouth of

which, in the northern ocean, are

the Dutch . . .

This Rio Grande should be the

Rio Doce or more probably, the Rio

Felipe, but Acuna affirms intensi-

vely that it is not the Orinoco. The

other chronicler of Pedro Teixei-

ra^ expedition, Alonso de Rojas,

however, has a different opinion,

and he writes that “there are peo-

ple who think this river to be the

famous Orinoco.”

Acuna and Rojas have been

unanimous that the rivers and the

whole country are very rich, that

the soils are very good ones, that

there are many nations of “bárba-

ros”, and that all together is by far

larger and richer than whole Peru.

This opinion of infinite riches, has

not yet died out completely, and

it has only been corrected by sci-

entific studies in the last few de-

cades. May be that their reports

contain some intentionally added

political influence, because Acuna

was a Spaniard and the lower Ama-

zon belonged to Portugal while

both nations were interested in the

still unoccupied western part of

Amazónia. Rojas even beats Acuna

in his enthusiastic description of

the splendor and the riches of the

country: “The discoverers of the

Amazon maintain that its campos

seem to be paradises, its islands

16

Atas do Simpósio sôbre a Biota Amazônica

gardens, and that, if art would sup-

port the fertility of the soil, these

parts would be well treated paradi-

ses and gardens. . “The river is

abounding in fishes, the moun-

tains are extremely rich in game,

the air is overabundant in birds,

the trees are full of fruits, the

campos give very rich crops, and

the earth is full of mines.” And he

tells of an enormous number of In-

dians — who, later on, after the

conquista, diminished very rapidly

so that Antônio Vieira writes in the

17th century that, within 30 years,

more than 2 millions of the Indians

on the lower Amazon and on the

coast till São Luís do Maranhão

were killed . . .

This circumstance does not be-

long to our theme, but I had found

it in the old reports and I did not

want to withhold it from you, be-

cause there may be some ecological

background in the fact that in the

following time during the Europe-

an occupation and introduction of

European methods of treatment of

the land, of agriculture, of exploi-

tation of the nature etc., the num-

ber of the neo-Brazilian and the

surviving Indian population always

remained extremely low and even

today it does not exceed two mil-

lions in the whole States of Ama-

zonas and Pará and the Territories

of Roraima, Rondônia and Amapá

together, i. e. in an area of more

than 2 1/2 million square-kilome-

ters . . .

As already mentioned, all main

points of posterior studies of Ama-

zonian waters are already touched

in the reports on Pedro Teixeira’s

expedition, written by Acuna and

Rojas, as e. g.:

Cartography and Hydrography

(map by the pilot of the fleet

and descriptions of a great

number of affluents);

River anastcmoses (first men-

tion of the connexion with the

Orinoco) ;

Mcrphology of the Rivers

(width and depth) ;

River-types (black-water of

the Rio Negro) ;

Rôle of the Várzea (fertility by

annual flooding) ;

Nutriment-household and Eco-

logy of the whole Region (“ve-

ry good” soils anywhere, num-

ber of native population).

To continue the history of stu-

dies of Amazonian waters, it is

now more instructive not to report

simply in a chronicle sequence, but

to follow up the development of

each of those different topics.

After the first map of the Ama-

zon according to the pilot of Pe-

dro Teixeira’s fleet, which contain-

ed the course of the Amazon itself

and the mouths of many of its

tributaries, it is only natural that

the most intelligent and broad-

Volume 3 (Limnologia)

17

minded among the early missiona-

ries and travellers tried their best

to contribute to a more exact and

more complete knowledge of the

big river-system.

One of the next original and fa-

mous maps of that time, in fact

the 5th map of the Amazon at all,

was the one by Pater Samuel Fritz,

S. J., of the year 1691.

Further on, not only the mis-

sions, but also the governmental

authorities were more and more in-

terested in better maps of our re-

gion, and there appeared maps, not

only from the main river with more

details, but also from some

affluents.

When in 1743/44 Charles Maria

de la Condamine, who had been

sent to the equatorial region of

South America for measuring the

first 3 degrees of a meridian, came

down the Amazon from Quito to

Pará, he designed a map of the

Amazon too, and so did other tra-

vellers of that period. The know-

ledge of the immense Amazonian

river-system grew more and more,

and also in Europe there were

printed new maps of that region,

but it shall not be said that each

new map, which appeared, signi-

fied a progress. So it happened

that, for giving their maps a more

impressive and more complete ap-

pearance, the designers also mixed

fantasy into the known facts which

were not too numerous.

Also the voyages of the first

scientific explorers of Amazónia

did not too much to improve the

cartography of our region. The

travellers described, often excell-

ently, the geographical conditions

the flora etc., corresponding to

their special interests and know-

ledges, but new measurements of

the rivers were very scarce.

A systematic mapping of the af-

fluents of the Amazon started only

in the second half of the last cen-

tury, when some of the scientific

travellers dedicated a good part of

their time and energy during their

trips to this purpose. The common

method, they used, was the survey

by the help of a watch and a com-

pass when they travelled in boats

on the rivers. I cite here only the

excellent map of the Rio Xingu,

made by Dr. O. Clauss on the oc-

casion of the ethnological expedi-

tion of Karl von den Steinen; it

contains exact geographical coor-

dinates for many points, indiea-

tions of the width of the river,

wherever possible, and even some

perfiles of the river-bed.

Perhaps the most important pro-

gress in the knowledge of the cour-

ses of a good deal of tributaries to

the lower Amazon was achieved by

the French explorer, Henri Anato-

le Coudreau and his wife, Olga

Coudreau, who, after having lived

and worked in the Guianas for mo-

re than 10 years, began to explore

2 — 37 121

18

Atas do Simpósio sôbre a Biota Amazônica

systematically those rivers in the

last decade of the 19th century.

Henri Coudreau visited first the

Southern affluents Tapajós, Xingu

and Tocantins — Araguaya, then

he turned to the northern side, to

the Yamundá and the Trombetas,

where he died at the end of 1899.

After his death, Olga Coudreau

continued the work of her hus-

band, travelling to the Rio Cumi-

ná, Curuá, Mapuera, Maycuru and

finally to the Rio Canumã. The re-

sults were always published with

the corresponding maps in a series

of books.

Naturally, also some captains or

pilots of the river-steamers, who,

during the famous “golden rubber

time” penetrated the Amazonian

interior as far as possible, had

drawn maps of their rivers: as an

example I am going to show you

a map of the upper Rio Juruá,

designed by Comandante Hilliges

from the little steamer “Marapa-

tá”.

One other important map, we

must not forget, is the one of a cer-

tain part of the lower Amazon, ma-

de by Paul Le Cointe, because it

did not restrict itself only to the

very bed of the river but it inclu-

ded the environment of that sec-

tion of the Amazon, too : all the pa-

ranás (side-arms) and the shore-

lagoons, the Várzea-lakes, and also

the edges of the terra firme to-

wards the wide valley of the Ama-

zon are indicated in that map. For

the first time one could get

now an idea of the morphology of

the valley of the lower Amazon,

which was formed by the activity

of the river with its erosion and se-

dimentation in seasonal floods and

drier periods.

Finally, all what was known

about the topography of the river-

courses and about the Hydrogra-

phy of the whole Amazon system

found its expression partly in out-

line maps, compiled in different

countries, partly in special maps

of single rivers, the best of them

being collected and published in a

now classical book “Hydrographia

do Amazonas e seus afluentes” by

Augusto Octaviano Pinto in 1930.

The first volume contains the most

detailed descriptions of all Amazo-

nian rivers, while the second vol-

ume is a collection of the best ri-

ver maps of those years.

All these maps, made with rela-

tively rough methods, were, of

course, however, subject to many

omissions and inaccuracies, which

could not be avoided by the lack

of well-determined coordinates,

and because of the impossibility

to establish a triangulation system

over a jungle-covered flat area of

some million of square kilometers.

This situation changed, when,

during the last war, the United

States Air Force started to make

the first aerial photographic map-

Volume 3 (Limnologia)

19

ping of the lower Amazon and

parts of the courses of some tribu-

taries, an enterprise, which was la-

ter on continued by Brazilian ins-

titutions as the Petrobrás etc. A

great part of Amazónia is now

mapped in this way, and since

about two decades, we have now

really authentic maps with the

exact courses of the rivers, of al-

ways greater areas of this large

country shown e. g. in the Atlas

do Brasil 1:1 000 000 of the Ins-

tituto Brasileiro de Geografia e Es-

tatística, or also in the World Ae-

ronautical Chart, also 1 : 1 000 000,

edited by USAF. By the use of ae-

rial photographs, the former dif-

ficulties of mapping the Amazo-

nian rivers were overcome, and the

history of Amazonian river carto-

graphy has come to an end. The

substratum for the “Studies in

Amazonian Waters” was known,

and new problems carne into the

centre of interests.

Only one principal difficulty still

remains, namely the presentation

of the extension of the Várzea-la-

kes of the Amazon, because they

shrink considerably in the dry sea-

son while, in the rainy season, the

water of the flood of the river co-

vers many times the whole valley

of the lower Amazon between the

two edges of the “terra firme”.

And one other feature, which is

highly desirable, is not yet indicat-

ed in these maps, i.e. these edges

themselves of the terra firme to the

Várzea filled valley of the Amazon,

and eventual “islands” of terra fir-

me within the same among the re-

cent river alluvions of the Várzea.

But these details do not belong

any more to a cartographic repre-

sentation of strictly only the river

courses, being of greatest impor-

tance, however, for an understand-

ing of the morphology and the

development in recent-geological

periods, of the valley of the Ama-

zon.

For those, who want to study in

detail the history of Amazonian

cartography a recently published

descriptive catalogue “A Carto-

grafia da Região Amazônica” by

Isa Adonias, which lists all maps

of this country, published between

1500 and 1960, is highly recom-

mended.

The geomorphological problems

of the Amazonian rivers have been

detected in their significance for

an understanding of the develop-

ment of the surface of Amazônia

to its present structure, only in re-

latively recent times. One excep-

tion are the river anastomoses

which exist in South America

among different river-nets and

which are treated first and very

intensively by Alexander von

Humboldt in his “Voyage aux ré-

gions équinoxiales du nouveau

continent”. It is a famous fact

that he was the first civilized per-

20

Atas do Simpósio sôbre a Biota Amazônica

son to prove such a connexion, that

between the Orinoco and the Ama-

zon system by the Cassiquiare, by

passing it in May 1804; Humboldt,

however, is not the discoverer of it:

Acuha already, as we heard, had

notice about it, and it also appear-

ed in maps of the year of 1778.

And Humboldt himself writes that

the President of the Mission in San

Fernando de Atabapo had given

him the route, he had to follow

from the Orinoco through small

blackwater rivers and finally by

bringing the canoe over a strip of

land of only 4000 toises (7,8 km)

of length to the Cano Pimichin

which leads to the Rio Negro, and

then back to the Orinoco through

the Cassiquiare. Humboldt follow-

ed this way and writes: “On the

first stretch on the course from

east to west, it” (the Orinoco)

“forms the famous bifurcation

which has been denied by the geo-

graphers so many times and the

position of which I was the first to

be able to determine by astrono-

mical observations...” Humboldt

also describes two further conne-

xions between these two river Sys-

tems, namely one arm of the Cassi-

quiare, which under the names of

Itinivini and Conorichite brings

“white” water of the Cassiquiare

into the Rio Negro, and another

one from the Rio Negro up the Ca-

baburi (= Cauaburi) to the Baria

and down this river into the Cassi-

quiare. The geomorphological im-

plications of these river-connexions

were finally discussed by Gourou

in 1950.

In this century, Jaguaribe de

Matos has occupied himself with

the studies of the connexions of the

Amazon system with other river

systems in South America. He

found that there are such anasto-

moses — besides those, described

by Humboldt — between the Ja-

purá and the Magdalena, the Uau-

pés and the Guaviare, the Gainía

and the Inírida, within the net of

the Rio Branco, between the Ma-

puera and the Essequibo, and in

the south between the Guaporé

and the Paraguai, the Tapajós and

the Paraguai, this last one in the

centre in South America. All these

anastomoses are, however, very

small and shallow, except the one

between the Guaporé and the Pa-

raguai, which is a bit deeper in the

rainy season. — But even small

boats are not able to navigate on

them.

The connexions among different

rivers show that the relief of the

surface of the earth in our region

must be old, that it must have been

strongly levelled while no impor-

tant catastrophic geological events

must have happened here for a

long period. All intense geological

activity in South America is con-

centrated on the range of the An-

Volume 3 (Limnologia)

21

Fig. 1 — Aerial photograph showing the rectangular structure of the

earth’ surface in Amazónia.

Fig. 2 — Delta of the Rio Branco into the Rio Negro (phot. Sioli).

des, which is in steady movement,

while the rest of the continent re-

mains relatively calm, i. e. without

any volcanic activity, without any

remarkable uplift or sinking of the

crust of the earth; so far as we

know, even no stronger earthquake

was reported in all eastern parts

SciELO

cm

10 11 12 13 14 15

22

Atas do Simpósio sôbre a Biota Amazônica

of South America during the whole

period of European colonization.

Besides this interest for geomor-

phology, the anastomoses among

so many South American river Sys-

tems are of importance for zoogeo-

graphical studies, because they

enable also the purely aquatic fau-

na to penetrate from one river-net

into the other ones.

An observation concerning the

phenomenon of river-anastomoses,

as considered in respect to the geo-

morphological viewpoints and the

development of the network of the

river-courses, was only made by

Sternberg less than two decades

ago. As we said, there had not hap-

pened any great or, still less, catas-

trophic movements of the earth’s

crust, but there were tectonic, pro-

bably eustatic movements even in

recent times, by which a strong

fracturation was caused. This frac-

turation, also proved by recent

geophysical prospections, which

were made by Petrobrás, broke the

earth’s crust into pieces of more

or less rectangular shape and gave

it a structuration, which deter-

mined strongly the general direc-

tions of the river courses. Stern-

berg reconstructed the fractures in

a map by following the orientation

of the main stretches of the river

courses. The result, shown in

Sternberg’s map, may seem a bit

theoretical or even arbitrary, but I

think the last doubts will disappear

when regarding an aerial photo-

graph, made somewhere in the vi-

cinity of Manaus, which can be

bought as a postcard in Manaus

(Fig 1). In this picture one can

clearly distinguish that this struc-

turation consists of a system of li-

nes, Crossing each other rectangu-

larly.

Another phenomenon of Amazo-

nian river morphology, linked with

geomorphological peculiarities of

our region and with hydrological

features of Amazonian rivers, e.g.

currents and sediment load, is the

formation of internai deltas, which

was first discussed by Humboldt.

We find such “deltas of affluents”

or “deltas of confluency”, e.g. at

the mouth of the Japurá into the

Solimões, of the Rio Branco into

the Rio Negro (Fig. 2), or at the

Southern end of the Estreitos de

Breves into the Rio Pará (Fig. 3).

That region of the Estreitos de

Breves and its current conditions

were described by Hartt, 1897/98

and especially by Huber, 1903; and

Tastevin reported on the delta of

the Japurá in 1929. The most re-

cent study on Amazonian internai

deltas is the one of Gilberto Osó-

rio de Andrade. These deltas occur

when the affluent of so-called

“white water”, has a heavy sedi-

ment load, and when the collector-

river cannot remove the added

load, because of general or local

current conditions, so that this

Volume 3 ( Limnologia)

23

Fig. 3 — Internai delta of the “Estreitos de Breves” into the Rio Pará (From:

Preliminary Map, Amazon Delta, 1 : 500 000, 1943).

load is accumulated near the

mouth of the affluent, dividing it

into many arms and having it

grown, so that the affluent reaches

out into the bed of the collector-

river.

The most striking feature of

many Amazonian clear-and black-

water rivers, however, is the shape

of their lower courses, their “mou-

th-bays”. The river water covers

there enormous areas, the width

of which is, at all, in no proportion

to the sizes and the discharge of

the upper courses. The shores ge-

nerally consist of pure white sand-

beaches behind of which rises the

terra firme, often in form of cliffs

of different heights. The shore-li-

ne is neither more or less streight,

nor consisting of alternating stret-

ches of erosion and sedimentation

banks, but it is jagged and, seen

from above (Fig. 4) the whole ri-

ver section looks like an artificial

reservoir. Even where such a river

24

Atas do Simpósio sôbre a Biota Amazônica

Fig. 4 — Rio Arapiuns, lower course with the shape of an artificial

reservoir (phot. Sioli).

is meandering, as in Fig. 5, the

meanders are those of a valley, not

of a river-bed.

Such a morphology of lower

courses cannot have been elaborat-

ed by the respective rivers under

their actual conditions, with their

practically stagnant water in the

mouthbays; they can only be un-

derstood as “drowned valleys”

what was pointed out first by De-

nis, 1927, interpreted them as true

freshwater rias. The cause of this

drowning of Amazonian river val-

leys, which is observed up to the

affluents of the middle Solimões,

where we still find large mouth-

“lakes” as that of Coari, Tefé etc.,

can easily be deduced from the

known rising of the ocean levei af-

ter the glacial period. If, besides

that fact, a regional sinking of the

continent crust must be taken into

consideration, is not easy to pro-

ve. That there must have happened

some up- and/or downward move-

ments of the earth’s surface can

be seen from the fact, that in the

region between the lower Tapajós

and the lower Xingu the affluents

of the Amazon have no mouthbays,

while east and west of that zone

we find those typical drowned val-

leys.

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All these affluents with such

mouthbays obey in their courses

one typical scheme (Fig. 6) .

After a “normal” upper course,

commonly in the arquean comple-

xes of granites and gneisses of Cen-

tral Brazil or of the Guianas, and

after passing the strips of paleo-

zoic marine sediments and of dia-

base eruptions, the rivers reach

the Amazonian depression, filled

with the relatively soft sediments

of the terciary freshwater inland

lake, the so-called “series of the

barreiras”. Here the river valleys

suddenly widen, but their first sec-

tion is filled with many, generally

elongated, islands, built up by re-

cent river alluvions. Only after pas-

sing that “sedimentation zone” in

which by the slowing down of the

current in the widened bed, they

deposit their sediment load, the ri-

vers reach the open mouthbays.

The water is now decanted, very

transparent, and, stretching out

over an enormous perfile of the ri-

ver bed, it looses its current almost

completely. Side erosion is caused

only by the activity of the waves,

which attack the cliff of terra fir-

me during the highwater season,

thus enlarging the river bed still

more. But there is no depth eró-

sion, on the contrary, bottom-sam-

ples and eco-soundings in the lo-

wer course of the Rio Arapiuns,

e. g. revealed a layer of very soft,

Fig. 5 — Rio Arapiuns, meanders of the drowned valley (phot. Sioli) .

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26 Atas do Simpósio sôbre a Biota Amazônica

— UPPER COURSE -- 1 | LOWER COURSE

Sedimentation-zone

with Formation of

Mouth-bay with

open Water

Fig. 6 — Scheme of the Imoer courses of Amazonian affluents.

muddy and fine sediments,

3 — 4 m thick (Fig. 7) typical for

laises, and which cannat be ac-

cumulated under the flowing wa-

ter of rivers. Also phytoplankton

develops in the open water of

mouthbays, even in such quantities

as to form waterbloom. So, the

lower sections of these Amazonian

tributaries, their “mouthbays”,

must limnologically be considered

more as lakes than as rivers.

The best term will certainly be

that of “Amazonian river-lakes”.

In the literature (Le Cointe, 1954,

de O. Andrade, 1958, de C. Soares,

1959) these mouthbays, the sec-

tions of drowned valleys of Ama-

zonian affluents, are also called

“lagos de terra firme”, “terra fir-

me-lakes” (contrary to the “lagos

de Várzea”, “Várzea-lakes”) , name-

ly because of their opening into a

white-water river, where the sedi-

ments of that turbid, suspension-

rich water have blocked by deposi-

tion of fresh alluvial lands the ori-

ginally widely opened funnel-

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-i..—

- .... .. — ■ — I ' .Ml M I .

- 33 -

- 20 -

a

~ —

S 69

b

-eo-

- 120 -

b

- 45 -

70

-Í0-

- 75 -

.t50~— — —

- 75 *

Fig. 7 — Echograms of the lower Rio Arapiuns, showing the layers of soft

“lake” - sediments.

mouths, letting only a narrow

channel as an outlet for water of

the tributaiy.

Also the valley of the Amazon

itself, where does not be such a

great, open and more or less stag-

nant water area as in the descri-

bed affluents, must be understood

as an originally “drowned valley”.

The clear- and black-water rivers

brought so little amounts of sus-

pended particles with their water

that they built up with these par-

ticles in the lower courses, after the

drowning of them, only a more or

less restricted sedimentation zone

which is still growing, by conti-

nuing sedimentation, in direction

to the river mouth but which has

not yet reached it. The Amazon,

however, is a turbid “white water”

river, i. e. its water contains a grea-

ter quantity of suspensoids (50 —

150 mg/l), and by deposition of

this material it has completed, sin-

ce a long time, the filling of its

wide drowned valley with its own

recent alluvions, which now form

the “Várzea”, the floodlands of

that river. And not enough that

the whole drowned valley has been

occupied by the “sedimentation

zone”, not letting any space for

wide and open mouthbays as in the

case of clear- and black-water ri-

vers, the river alluvions of the

Amazon have been accumulated

even outside its mouth into the

ocean, along the Guiana coast,

where the Amazon water is con-

ducted along the continent shore

by the Brazil-Current of the Atlan-

tic Ocean. There they are extended

in front of the terra firme as a strip

of swampy, floodable land, a con-

tinuation of the lower Amazonian

Várzea, in a width of up to more

or less 80 km and reaching to

French Guiana.

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Atas do Simpósio sobre a Biota Amazônica

Related to the phenomenon of

the drowned valleys is the great

depth, found in some places in the

bed of the lower Amazon. Spix &

Martius were the first to measure

the depth in the gorge of this ri-

ver at Óbidos, where they found

83 m. The recent eco-soundings of

the American group (U. S. Depart-

ment of the Interior Geological

Survey Information Office, 1964)

in the lower Amazon found several,

at least 10 places with a depth of

90 and more meters. But if the

“mouthbays” of affluents are in-

deed drowned valleys, it may be

possible that there also persist

great depths and that the original

bottom of the riverbed may be ma-

intained, if no products of side-ero-

sion or deposition of “lake-sedi-

ments” filled it up in the meanti-

me. Really, a sounding, made by

hand with a line in the Rio Negro

below Manaus, south of the island

Marapatá, where the river is so

wide that there was no notable

current, indicated a depth of . . . .

102 m. And later eco-soundings re-

vealed the perfile of the ancient

river on that place as a deep, al-

most canon-like valley, as shown in

Fig. 8 (Sioli, unpublished) .

The morphological peculiarities

of Amazonian rivers which we de-

scribed and interpreted — except

that of the river courses along frac-

ture lines — are consequences of

Ri

A/

* Sv

CAREIRO

Fig. 8 — Echograms of the Rio Negro, indicating a greatest

depth of around 100 m.

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the flatness of the country, the

very small gradient of the rivers

in it (the Amazon having only

*« 1 cm/l km between the mouth

of the Rio Negro and the ocean)

and the very ancient and “old”

i. e. levelled relief of the country,

even in many headwater regions.

In spite of that small gradient,

the current speed of the Amazon is

really high, varying in the lower

Amazon in an average of 1 to 2 mi-

les per hour ( J / 2 — 1 m/sec.) in the

dry season, and 2 to 4 miles per

hour (1 — 2 m/sec.) in the flood

season. This high current speed at

a given gradient naturally depends

on the relation: water quantity/

friction on the surface of the river-

bed, or: perfile through the river-

bed/contact-line of the water with

the bedground. The greater the

water .quantity, flowing down the

river, the smaller is, relatively, the

friction-zone between the running

water and the surface of the ri-

verbed. How much water, now, is

flowing down the Amazon?

The discharge of the Amazon

was, till very recent years, only es-

timated but not exactly deter-

mined. The first estimate, however,

made by Katzer (1897), which un-

fortunately, has almost been for-

gotten and is not mentioned in mo-

dem literature treating especially

this question, has been astonish-

ingly precise. Katzer found that

the discharge of the Amazon into

the ocean is around

120 000 m 3 /sec. in the dry season,

an amount which might be multi-

plied in the highwater season. Par-

dé (1936), basing on calculations

about rainfalls, evaporation etc.

carne to much smaller amounts,

namely only 90 000 — 110 000 m 3 /

sec. as annual average. But final-

ly, the recent determinations with

most exact methods, made by that

American group (U. S. Department

of the Interior Geological Survey,

1964; Oltman, 0’R. Sternberg,

Ames & Davis, 1964; Sternberg &

Pardé, 1965) gave as result an ave-

rage of 218 000 m 3 /sec. all over the

year, a figure, which could not bet-

ter confirm the indication of Kat-

zer/ This means that the Amazon

is by far the mightiest river of the

world, having 5 times the water of

the Congo and 12 times of the Mis-

sissippi, and carrying 15 to 20% of

the water which all rivers of the

world together conduct into the

oceans. Corresponding to that

mass of water is the extension of

the estuary of the Amazon, where

Orellana and his chronicler Car-

vajal aldready admired the width

of the mouthfunnel. Special studies

about currents in and displacement

of the mixing zone of fresh and

sea-water and of other limnolo-

gical conditions in the estuarine

section of the Amazon were made

by Egler & Schwassmann (1962,

1964).

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Atas do Simpósio sôbre a Biota Amazônica

The enormous mass of water of

the Amazon, running down the

wide and deep riverbed with strong

current, does not carry in its tur-

bid “white” water only a certain

amount of suspended particles, but

it also moves the bed load on its

bottom, the quantity of which can-

not yet be determined. It appears

in sandbanks, which change their

height and position by the shifting

of the movable material. Where it

wanders, however, on the bottom

of the riverbed, it forms gigantic

“ripplemarks”, true sanddunes of

up to 190 m length and 8 m height

Fig. 9 — Giant “ripplemarks” (sand dunes) on the bottom of the Amazon

heleno the confluence zoith the Rio Negro. Echogram of a longitudinal

section of the riverbed.

Volume 3 (Limnologia)

31

as to be seen in Fig. 9 which shows

a longitudinal perfile, taken by

eco-sounding of the Amazon below

the mouth of the Rio Negro (Sioli,

1965).

We spoke already of turbid “whi-

te” water, of clear water and of

black water rivers, and with these

expressions we mentioned the clas-

sical river types of Amazônia. We

also heard above what Carvajal

had written about the black water

of the Rio Negro, when Orellana

and his men had seen it first, and

how Acuna and Rojas had describ-

ed that strange water, too. The

first scientist to discuss the pheno-

menon of blackwater rivers was,

however, Alexander von Hum-

boldt, who did not only describe

the appearance of such rivers, to-

gether with some biological pe-

culiarities of them as e. g. lack in

crocodiles ( Caiman spp.) and in

black-flies (Simulidae) , and who

cited the opinion of the people

that these black waters do not turn

the stones brown and that white

rivers have black, black rivers have

white shores, but who asked alrea-

dy for the origin and the reasons

for that black water! He writes

(Humboldt, 1. c., vol. 3, pp

264-266) : “In the widely extense

river-system that we travelled —

and this circumstance seems to me

very striking — the black waters

occur preferably only in the stretch

near the equator . . . ; but in that

whole area, white and black wa-

ters occur in the forests and

on the savannahs simultaneously

one near the other, in a form that

one does not know to what cir-

cumstance one shall contribute the

coloration of the water . . . If one

asks the Indians about the reasons

for this strange coloration, their

answer is, . . . : they repeat the

fact in other words. If one address-

es oneself to the missionaries, they

speak as if they had the severest

proofs for their conjecture, “the

water colours when it runs over

the roots of Sarsaparille”. The Smi-

laceae are, indeed, very common ut

the Rio Negro, Pacimony and Ca-

babury, and their roots give, soak-

ed in water, a brown, bitter, sli-

my extractable mater; but how

many Smilax - bushes have we seen

at places, where the waters are

completely white! How is it possi-

ble that in the swampy forest

through which we had to carry our

pirogue from the Rio Tuamini to

the Cano Pimichin and to the Rio

Negro, we waded through the same

stretch of land, now through

creeks with white, now through

other ones with black water? . . .

Very near the equator, indeed, the

vegetation is, because of the quan-

tity of rains, stronger than 8 —

10 degrees to the north and to the

south; but in no way it can be

maintained that the rivers with

black water have their origin pre-

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Atas do Simpósio sobre a Biota Amazônica

ferably in the most dense and sha-

dowy forest. On the contrary, very

many “águas negras” come from

the open grasslands which extend

from the Meta on the other side

of the Guaviare to the Caquetá. . . .

The colour derives, without any

doubt, from coaled hydrogen. One

can observe a corresponding ap-

pearance on the manure-water

which our gardeners prepare, and

on the water which flows out of

peat-pits. Cannot, after this, be as-

sumed, that also the black ri-

vers . . . are coloured by a com-

pound of carbon and hydrogen, by

a plant-extract-matter? . . . The co-

louring matter seems to be in very

small amounts in the water; for,

boiling water from the Guinia or

the Rio Negro, I di not see that

it turned brown like other liquids

which contain much hydrocar-

bon”.

At the times of Humboldt and

later on, one distinguished only

two types of Amazonian rivers:

white and black ones. But we have

in fact three different types (Sio-

Li, 1951, 1964), namely

Rivers with turbid yellowish,

so-called “white” water, with

a transparency between 10 and

60 cm, as the Amazon, Rio

Madeira, Rio Branco;

rivers with more transparent

water of yellowish to green

and olive-green colour and a

transparency between 60 cm

and 4 m, to be called “clear”

water rivers, as the Tapajós,

the Xingu and the majority

of small creeks in the terra fir-

me high forest;

rivers with transparent but

olive-brown to darker even

reddish-brown water, looking

like black coffee in the river

bed, in a glass like weak tea,

with a transparency of 1 —

2m, so-called black-water ri-

vers (as described above), as

the Rio Negro (the “classic”

black water river) , Rio Cururu,

and certain creeks coming

from areas with a special ve-

getation which grows on a

certain soil type .

These three types of running

waters in Amazônia result from

characteristic landscapes, i. e. from

the geomorphological and/or mi-

neralogical-pedological conditions

in the headwater areas.

White waters are bound to more

or less mountainous terrain in the

region of their origin, with an ir-

regular relief, where erosion fur-

nishes the sediment load of the wa-

ter (mainly the Andes or their

foot-hills, or also the Parima-sys-

tem on the Venezuelan border) .

Clear water rivers have their

catchment areas in the less rugged,

really strongly flat reliefs of the

old massives of Central Brazil and

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Volume 3 (Limnologia)

33

the Guianas, or in the terciary se-

diments of the Amazonian terra

firme plains, with their characte-

ristic brown loam soils.

The black water rivers come

equally from very flat regions; the

Rio Negro, for example, rises on a

very old peneplain. That is the rea-

son for the little contents of sus-

pended matter, but not for the

brown colour of those waters. As

shown above, Humboldt already

discussed the origin of that brown

colour. One thought also that the

colour had its origin in the decay-

ing organic matter of the flooded

jungle, of the so-called igapó-fo-

rests. This possibility has not been

refuted nor proved — , but it could

be shown (Sioli, 1954a, 1955b)

that the black water is coloured by

dissolved or colloidal humus sub-

stances which are linked with a

special soil type, namely, bleached

white sands, covered by a special

vegetation, the caatinga-forest of

the upper Rio Negro, the “campi-

nas” near Manaus and certain

“campos” as e. g. around the Rio

Cururu. These bleached sands re-

vealed themselves as tropical low-

land podsols, first indicated by

Chemical analyses of the black

waters, later proved by pedological

investigations (Sioli & Klinge

1961, Klinge 1965).

As we see, there are physical fac-

tors (relief) as well as Chemical

ones (soils) in the headwater re-

gions which create the types of

running waters in Amazónia. And

we can make even a scheme of the

combinations of the physical and

Chemical factors which are neces-

sary for the formation of the river

types:

TABLE 1

Factors of the headwater zones which determine

the types of Amazonian rivers

Mountain-slopes

(as primary

supplier of the

suspended matter)

+ Even relief

of the earth’s

surface

Podzol soils

(as supplier of

the eolouring

humus substances)

Other soils

White waters

+

—

+

Clear waters

+

—

+

Black waters

+

Such a connexion respectively

exclusion also clarifies the pheno-

hienon that black waters are very

uniform in regard to their chem-

isms, that also white waters do

not Show too great divergences, at

37 121

cm l

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Atas do Simpósio sôbre a Biota Amazônica

least in the pH values, but that

clear waters present the very great-

est differences in pH and in the

crntents of inorganic ions:

black waters: pH 3.8 — 4.9

white waters: pH 6.2 — 7.2

clear waters: pH 4.5 — 7.8

The lower pH-values (around

4.5) of the clear waters occur in

creeks in the region of the “Série

das barreiras”, a bit higher ones

(around 5) in creeks of the ar-

quean granite-zones of the upper

Rio Negro, while the great clear

water rivers have pH 6 to 6.7. The

highest pH-values are found in the

strips of carboniferous origin north

and south of the lower Amazon,

with occurrences of limestone

and gypsite-deposits. Already this

spread of the pH-values and the

distribution of the clear waters

over the most different geological

zones of Amazônia show that the

clear waters are only a collective

name of chemically (and biologi-

cally) very heterogenous waters

and that they possess only the

scarcity of suspended matter as

coramon characteristic.

The described river types are not

always clearly distinct from each

other. In nature we find transi-

tions of all degrees between white

waters and clear waters, and bet-

ween clear waters and black wa-

ters. Also one and the same ri-

ver sometimes can change its

“type” periodically or occasionally

with the seasons or even with ev-

ery single rainfall. Much less than

a lake, a river is determined in its

characteristics by its own, internai

laws, being only a product of its

surrounding landscape, mainly in

the headwater zone, its water is

chemically spoken the “urine of

the landscape”. Thus, we now see

that the river types are not abs-

tractions, “ideas” of rivers, but

more or less rough descriptions of

sections of the framework of causes

and effects of the eco-system,

which constitutes a landscape

(Sioli, 1965d).

Rivers, however, do not receive

only their qualities from the sur-

rounding landscape, they are also

able to build around them their ty-

pical landscape. We saw already

the scheme of the course of the

clear water rivers, with the “nor-

mal” upper course, the sedimenta-

tion zone and the mouthbays with

the sandbeaches.

Also the Amazon, as greatest

white water river, has built its ri-

ver landscape, a schematic cross

section of which we see in Fig. 10

(Sioli, 1964b).

The wide valley of the river bet-

ween the terra firme slopes, carv-

ed out probably during the gla-

cial period and then drowned, was

filled in the meantime with recent

river alluvions which form the

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Valley of the Amazon

£ :

Fluvial

island

O w (Ã

Tarclary aedimenta

of "Serie* of the

Barreira*'*

Terrain* of recent alluvions

-Maximum highwater-level

* Mlnlmum lowwater-level

Terciary sediments

of "Series of the

Barreiras"

Fig. 10 — Schematic cross-section through the Lower Amazon valley; height

exaggerated (From: Sioli, 1964 b).

flocdlands of the so-called “Vár-

zea”. The Várzea is covered with a

special vegetation type, different

from the high forest of the shores

of clear and black waters. This

may be taken as an indication

that the Várzea-forest is growing

on soil with (Chemical or other)

qualities different from the behind

terra firme soils. Our schematic

cross section is derived from the

conditions at the lower Amazon.

But the more we go up the Ama-

zon, the Solimões, the more we

approach the foreland of the An-

des, the more vanishes the diffe-

rence between Várzea and terra

firme, the more the vegetations

become equal . Acuna already cha-

racterized the Várzea of the lower

Amazon as a very fertile land, of

which the Indians profit with their

plantations and which is fertilize:

annually by the flood of the Ama-

zon which every time lets behind

a new layer of fresh sediments.

After Fittkau (unpublished) , the

Várzea must now be understood as

an extraneous element in the

lower Amazonian landscape, as an

appendix-like prolongation of the

pre-andean strip of material

which originated from the fresh,

and relatively nutrient-rich pro-

ducts of the weathering crust of

the mountains and has been wash-

ed down, by the waters, from the

slopes of the Andes and deposited

first near their feet, in their fore-

land. From there, these “fertile”

sediments had been transported

down the white water rivers where

they were deposited and eroded on

the way probably several times be-

fore they built the Várzea of the

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Atas do Simpósio sôbre a Biota Amazônica

lower Amazon, from where they

will finally be taken to the ocean.

Perhaps the most important

chapter of the studies in Amazo-

nian waters is that of the chemis-

try of rivers and, still more, of

creeks, because it did not only

reveal some peculiarities of the

waters themselves — important as

they are for an understanding of

their biology, inclusive their rôle

for the distribution and expansion

of certain human diseases — but it

showed relations between water

chemistry and geology/mineralogy

as well as pedology of the head-

water areas, and finally it led to

first insights into the nutrient-

household of whole Amazonian

landscapes, to the ecology of the

rain-forest .

The first Chemical analyses ever

made of Amazonian waters are tho-

se by Katzer by the end of the last

century (Katzer, 1897, 1903) : “A

short time ago, one knew almost

nothing about the quality of the

water of the Amazon. Only by the

studies of the last time, there has

been proved that the water of the

giant river is, in Chemical aspect,

of extraordinary purity. The same

is true, partly in still higher de-

gree, for its affluents as far as they

were analysed for this purpose so

that, indeed, the rivers and stre-

ams of lower Amazônia belong to

the purest waters of the world.”

And, after Katzer, the waters of

many springs and the ground wa-

ter in the lower Amazon region are

of the same quality.

During the last 20 years this

statement has been confirmed by

a lot of Chemical analyses of wa-

ters from many parts of Brazilian

Amazônia, from the Zona Bragan-

tina, east of Belém, to Benjamim

Constant at the Peruvian border,

and from the Southern limit of the

Hylaea near the upper Tapajós Ri-

ver to the Campos of Rio Branco

and the frontier-mountains of Ve-

nezuela in the north. While the wa-

ter of the main river, the Amazon

itself, is already extremely poor in

its ionic content, as Katzer and

later determinations showed, the

same condition is true in a still

higher degree in most parts of

Amazônia, where the natural

waters may be compared best with

“a little bit contaminated distilled

water”. In the area of the so-called

‘‘Series of the barreiras”, i. e. of

the terciary (pliocene to pleistoce-

ne) deposits of the then enormous

Amazonian freshwater-inlandlake,

in the arquean complexes of Cen-

tral Brazil and of the Guianas,

with their granitic gneissic rocks,

in the zone of cretaceous (?)

sandstones around the Rio Cururu

(near the Serra do Cachimbo) , the

waters of the creeks and springs

and of eventual lakes are all of

that quality and of surprisingly

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low pH-values. But we have also

some other regions in Amazônia,

where the waters are not so poor

and acid, even if these zones are

of relatively small extent in

lower Amazônia, namely restricting

themselves to the narrow strips of

carboniferous marine sediments,

with limestone and gypsite depos-

its, north and south of the lower

Amazon, to the “islands” of dia-

base eruptions, and to the area of

a miocene sea-transgression in the

Zona Bragantina, east of Belém —

Pará, the so-called Formation

Pirabas.

TABLE 2

Chemistry of Amazonian Waters

pH

4.2 — 5.5

4.0 — 6.6

5.2 — 7.8

HCCVmval/l

0.00 — 0.04

0— 0.174

0.026— 6 311

Ca" mg/l

0 1-5

0— 18.4

2.6 —204

Mg" mg/l

0— 0.38

0— 5.6

—

Na' mg/l

0.847 — 2.530

0.245— 2.060

—

K' mg/l

Li' mg/l

Fe" + Fe"' y/l

0.534— 1.52

0.143— 1.000

—

0 — 143

0 — 0.160

0 — 250

0 — 1.200

Mn" 7-/1

0—82

0 — 212

0—160

Al"' y/l

0 — 488

0 — 314

0

Cl' mg/l

0— 3.5

0— 2.5

0— 16.5

S0 4 " mg/l

0.000— 0.480

0— 2.690

0 — 556.7

P (PO/") 7/1

0— 50.2

0 — 110

0—42

N (NO»') 7/1

0 — +200

0— +150

0— +550

N (Kjeldahl) 7/1

138 — 724

0 — 2.620

—

Si diss. mg/l

+ 0.5 — 4.5

0.502— 6.650

1.5 — 22.4

Table 2 shows the extreme va-

lues of the results of very many wa-

ter analyses of the cited regions.

It is obvious that the chemistry of

the waters is neatly related with

the geological, i. e. mineralogical

underground of the region, it co-

mes from. Naturally, that had to

be expected, but in Amazônia tho-

se relations are surprisingly evi-

dent, thanks to the large-scale geo-

logical structure of our region. Ba-

sed on that experience, e. g. even

the delimitation of the extension

of the miocene marine transgres-

sion of the Formation Pirabas in

the Zona Bragantina once was

tried, and I think, with certain

success.

Where there are some lakes in

Amazônia — and they are practi-

cally all shore-lakes of some rivers

— their water is also related to

the geology of the surrounding

and, naturally, via the river, of the

headwater zone of the same. The

limnology of such lakes was first

studied by Braun (1952), more re-

cently by Marlier (in press a, b).

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The most interesting example

for that relation between shore-la-

kes and their river and the head-

water region of the same, we saw

already in the Amazon itself, the

Várzea of which is a landscape-

strange element in lower Amazô-

nia. The water of the Várzea-lakes,

however, is of double quality. In

part, it comes from the Amazon,

when the river, with the rising

flood, overflows into the lagoons

where it diminishes its turbidity by

decantation of the suspended par-

ticles, while getting more or less

stagnant; from behind, from the

slopes of the terra firme, however,

those várzea-lakes receive very

poor, clear and acid water, which

often prevent the Amazon water

from reaching the terra firme

shore of the várzea-lakes.

A consequence of the chemically

richer Amazon water, which beco-

mes decanted in parts of the Vár-

zea-lakes, is that the waters with

the greatest primary production of

phytoplankton are to be found

here. In the turbid “white” water

rivers, light penetration is too

small for allowing an autochtho-

nous high primary production; in

regard to the alimentation of the

biota, living in them, these rivers

are dependant biotopes. I. e. they

depend on the introduction of or-

ganic matter, of phytoplankton

from the shore-lakes and from the

mouthbays of clear water rivers for

the beginning of the food-chain.

On the other hand, we find in the

várzea-lakes the upper layer some-

times thick green from water-

bloom, and the pH, during the

clear day, risen to almost 10 by

the consumption of CO- by the

photosynthetic processes of that

enormous mass of algae.

It is no wonder that just in and

around those várzea-lakes there is

also the most intensive concentra-

tion of higher animal life, from

fishes to enormous amounts of wa-

ter birds. In the white water ri-

vers, as e. g. in the Amazon, as well

as in the lakes and in the

sedimentation zones of great clear

water rivers, we have, however,

another biotope of good primary

productivity. These are the floating

meadows of grasses etc. which de-

velop in calm river stretches and

inlets on the water surface, thus

being independant from the turbi-

dity of the water and profiting only

from the inorganic nutrients in the

water through the floating roots.

Also the mouthbays of great

clear water rivers, as the Tapajós

and the Xingu, are, as I said,

places of primary production of

phytoplankton. Sometimes we can

there observe even waterbloom,

too, but never in such a quantity

as in the cleared-off Amazon water

of the várzea-lakes. The limiting

factor must be sought in the inor-

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ganic nutrient content of those

great clear water rivers, which ge-

nerally come from the old massives

of Central Brazil and from the

Guianas, and not in scarcity of

light, as is the case in the white

water bodies.

And where we have the acid and

chemically extremely poor “black”

water, even in so great and lake-

-like mouthbays like in the lower

Rio Negro, the Chemical poorness

and the dark colour of the water

combine for reducing the primary

production to extreme low values.

Those large black water rivers have

the general fame to be hunger-ri-

vers, also for the human popula-

tion, living on the banks, caused

by the scarcity of fishes and wa-

terfowl etc. Where there are igapó-

forests on their banks, these, with

their litter etc., must be the main

source of organic matter to start

the food Chain in them.

General characteristics of the

Chemical properties of Amazonian

waters, also in relation to soil con-

ditions, were examined and dis-

cussed by Klinge & Ohle, 1964.

The water of the Amazon itself,

as well as of the Rio Negro, was

also investigated especially by Ges-

sner, who compared these rivers

with the Orinoco. After him, the

electrolytical conductivity in Ama-

zonian waters is generally very low,

in clear water rivers still by far

lower than in the Amazon itself,

but rises with the pH, when this

exceeds ± 5. Below that value, the

conductivity rises again with a fal-

ling pH-value. The Amazon has its

highest conductivity in the upper-

most part of its course; downward

it diminishes by “dilution” with

the waters of low conductivity of

the affluents. The oxygen content

in the Amazon water is around

70% of saturation, having the low-

est value during the high water

period. For the phosphate content,

the sediments of the Várzea act

as a buffer system.

We have now seen in which way

the chemistry of the water in Ama-

zônia is related to the geology-mi-

neralogy of the underground of

their headwater areas and, already

before, how it indicates some pro-

cesses which occur in the soils, e. g.

podzolisation . But we must con-

sider yet, what the Chemical poor-

ness of the waters tells about the

ecology of the landscapes from

which they come. This is possible,

because the landscapes with their

relief, their soils and their vegeta-

tion etc. are interposed in the cir-

culation of the water on earth and

determine the quality of the

waters, which pass them . Galenus

already knew about this connexion

when he said: “Tales sunt aquae

quales terrae quas percurrent.”

The water, which appears in

springs and then forms creeks

and rivers, comes, in the last

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Atas do Simpósio sôbre a Biota Amazônica

end, only from the rain, which

falis on the bottom and partly

flows away on the surface, partly

penetrates the soil before reaching

the groundwater, where it even-

tually comes into contact with the

subsoil and finally drains into the

springs. Passing the soil and being

in contact with the deeper under-

ground, it enriches itself with ions,

which originate there from wea-

thering- and soilforming-proces-

ses. When — as in the Amazonian

hylaea — the earth’s surface, un-

der the influence of a humid cli-

mate, is covered by a climax vege-

tation, the mass of which is cons-

tant during long periods, none óf

the ions liberated in the soil by the-

se weathering etc. processes from

the reserves, is additionally accu-

mulated in the vegetation cover

or in the upper soil layer where,

with time, such an accumulation

would provoke salting, but all will

be washed out and appear in the

springs and creeks where the ions

can be analysed, qualitatively and

quantitatively. And if we find so

little ion content in the waters —

a part of which must even still be

contributed by the influx of the

rains — as we do in the already

mentioned zones of Amazônia, we

are enforced to conclude that also

the soils must be very poor in those

ion reserves, among which the

macro- and micro-nutrients for

the plant growth are of special in-

terest for the understanding of the

“budget” of the high rainforest as

well as for prospects of a practical

utilization of those areas for even-

tual future agricultural or silvicul-

tural purposes. The general Chemi-

cal poorness of the waters indica-

tes an equally general poverty of

the soils, and when we find these

covered by high forest, the existan-

ce of the forest is not to be explain-

ed by a supposed “fertility” of the

soil, but by the fact that the fo-

rest lives in a short-circuited cir-

culation of the mineral nutrients

within the living and dying organ-

ic matter, more or less isolated

from the soil. The forest uses the

soil more as a mechanical substra-

tum for the trees than as a source

of nutrients.

The minerais, contained in the

forest matter, have there been ac-

cumulated during centuries or

thousands of years. If now, the

forest is cut down and burnt for

giving space for a plantation, these

minerais, and among them the nu-

trient-salts, are liberated at once

in the ashes. But already the next

rains will wash the greatest parts

of them away — as once was found

occasionally when examining

creeks in the area of the “Series of

the barreiras”, in lower Amazônia

— , only small amounts still remain

for the crop and will be carried

away with the harvest. It is a ge-

neral experience that a new “roça”

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41

in the jungle gives good harvests

only during two, exceptionally

three years. Then the soil is ex-

hausted, the mineral reserves of

the former jungle-cover have dis-

appeared.

The conclusions as to the “fer-

tility” of the soils which have been

drawn from the results of Chemi-

cal analyses of waters from the

greatest parts of the Amazonian

region were simultaneously and la-

ter on confirmed by soil-analyses

and by practical experiences which

all contradict the former idea of a

never ending fertility of our re-

gion.

These findings are, however, nei-

ther a reason for being shocked,

nor for despair in regard to a be-

neficiai contribution of Amazônia

to the food-economy of the grow-

ing population of Brazil. It only

says that care must be taken not

to waste uselessly the resources of

our country and that new me-

thods, which correspond with the

ruling ecological conditions in

Amazônia, must be applied and

even still created by studies in loco

instead of importing only methods

and machinery and ideas from hi-

ghly industrialized countries, in

which these were developed, gene-

rally under completely different

conditions. All must be done to

avoid a devastation of Amazônia

which may easily happen because

the ecological equilibrium is really

unstable and very vulnerable in

consequence of the shown lack of

buffering nutrient reserves. There

exist already enough examples of

devastated landscapes in other tro-

pical countries of South America

and also of África. Investigations

of the waters may also help to con-

tribute some knowledge for the

purpose of avoiding dissipation of

singular riches and benefits con-

tained in the Amazonian nature.

That is also one aim when elabo-

rating a budget of inorganic nu-

triente for catchment areas of

whole river systems, as Dr. Unge-

mach is just doing, or when esta-

blishing an ecological subdivision

of this huge country, as is tried by

Dr. Fittkau. These two scientiste

are going to report on their work

during this symposium.

And so we learn that the studies

of Amazonian waters are also

linked with the observation about

the supposed fertility of the Ama-

zonian soil, mentioned by Acuna

& Rojas.

Finally, I should like to say that

it was only along very general lines

and under omission of many stu-

dies and works that have been

done, that I tried to give an idea

of the points of view under which

Amazonian waters were observed,

described and analysed, from the

very first contate of Europeans

with them on the occasion of the

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Atas do Simpósio sôbre a Biota Amazônica

discovery of the mightiest river of

the world, to the concept of the

waters being parts of greater sec-

tions of the biosphere, what are the

landscapes, and of using them, too,

as indicators for other, more gen-

eral ecological conditions in the

nature of this big country.

SUMMARY

There is no other region in the

world in which the water plays an

equally decisive rôle, in the for-

mation and in the character of the

landscape, as it does in Amazônia.

The wet climate created, in the

enormous lowland, the greatest

and vastest river-system on earth.

Already the discovery, the con-

quest and the colonization of our

region were connected with the

water-courses so that their know-

ledge was, from the beginning, of

vital importance for the Spaniards

and Portuguese when they made

themselves rulers of the new coun-

try. The studies in Amazonian

water started therefore with the

mapping of the water-courses; the

improvement of that task was con-

cluded only in recent time with the

elaboration of the modern maps

based on aerial photographs.

The chroniclers of the expedition

of Pedro Teixeira in 1637/38 —

the first one to ascend and to des-

cend the Amazon in a planned trip

from the mouth to the Andes — ,

Acuna & Rojas, however, were

observers with such a wide look

that they perceived, in principie,

almost all aspects which the Ama-

zonian waters later on offered to

the scientific curiosity of mankind.

Besides of the cartography — and

of the hydrobiology which will be

treated, in this symposium, in a

special paper given by Marlier —

those reports already touched the

following complexes:

Anastomoses between different

river-systems (by the mention

of the connexion between the

Rio Negro and a river which

leads to the ocean) ;

Morphology of the rivers (by

giving dates about widths and

depths) ;

River-types (by the descrip-

tion of the black water of Rio

Negro) ;

Peculiarity of the Várzea in

the complex of the Amazonian

landscape (by the observation

of its periodical fertilization by

the annual floods) ;

Nutrient-content and Ecology

of the whole region (by the

judgement — even being an

enormous one — of the quali-

ty of the soils).

River-anastomoses between dif-

ferent fluvial systems have been

scientifically proved for the first

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43

time by Humboldt who navigated

through the Cassiquiare. Today,

more connexions between the Ama-

zonian and other Southamerican

river-systems are known.

In the Morphology and Hydrolo-

gy of the Amazonian rivers the fol-

lowing problems occupy the great-

est interest: the perfiles of the

beds of the big rivers, the lake-

shaped lower courses of many

affluents, and the discharge of the

Amazon. The first measurements

of great depths (e. g. in the “gor-

ge” of Óbidos, Spix & Martius

found 83 m) were proved and even

surpassed by recent eco-soundings

in the Rio Negro (~ 100 m) and

in the lower Amazon. The bed-

-ground of the lower Amazon con-

sists of load-matter which is mov-

ed down the river of giant “rip-

plemarks”, of true dunes. The low-

er courses of many affluents which

are disproportionately widened

and transformed even in “Terra

firme — lakes”, have been recogn-

nized, first by Denis, as drowned

valleys; limnologically, the sections

of river-courses are more alike to

lakes than to rivers. The discharge

of the Amazon, exactly measured

only recently, is of 218 000m :i /sec

in the annual average, i. e. 1/6 to

1/5 of the water-mass which all ri-

vers of the earth together empty

into the oceans.

The following river-types were

established in Amazónia: rivers

of “white” (turbid) water, of clear

(transparent) water, and of bla-

ck” water (transparent but brown

coloured). The types depend on

landscape-factors in the headwa-

ter-zones (relief, climate, vegeta-

tion cover) , but they are not abso-

lutely distinct from another and

permanent, but they may be con-

nected by intermediate types, or

they may even periodically or occa-

sionally change within the same

river.

The Várzea, the floodland, of the

lower Amazon which is so diffe-

rent from the Terra firme in the

quality and fertility of the soil and

in the vegetation, is explained as

the product of geologically recent

filling of the drowned valley of the

Amazon with the river-alluvions;

it is therefore, after Fittkau, a pro-

longation, along the course of the

white water of the Amazon, of the

sediment-matter from the pre-an-

dean strip of land, an appendix to

the same through Lower Amazó-

nia. This sediment-matter from the

pre-andean strip differs, by its geo-

logical-mineralogical origin and

its age, in its geological qualities

from the soils of the arquean and

terciary Terra firme zones of the

lower Amazon.

The nutrient-content was con-

cluded by Chemical analyses of ri-

vers, creeks and ground-waters. Al-

ready the first analyses made by

Katzer showed a surprising pover-

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Atas do Simpósio sôbre a Biota Amazônica

ty in dissolved salts. Later analyses

of waters from different geological

zones confirmed that general Che-

mical poverty with only few excep-

tions, e. g. in the carboniferous

strips. Such Chemical poorness of

the running waters is an expres-

sion of a corresponding poverty, of

the soils of the headwater zones,

in the same ions, among them also

in nutrients for the vegetation. The

chemistry of the water revealed

itself, by the way, as an excellent

indicator for getting a first idea of

the Amazonian landscape-ecology,

too, especially of the nutrient-

household of the ecosystem of the

Amazonian Terra firme with tne

high rain-forest.

SUMÁRIO

PESQUISAS EM ÁGUAS DA AMAZÔNIA

Não há nenhuma outra região no

globo na qual a água faz um pa-

pel igualmente decisivo, na forma-

ção e no caráter da paisagem, como

na Amazônia. O clima úmido fêz

desenvolver-se, naquela enorme

planície baixa, o maior e mais ex-

tenso sistema potâmico do mundo.

Já o descobrimento e a conquis-

ta e a colonização da nossa região

eram ligados aos corpos d’água de

forma que o conhecimento dêstes

foi, desde o início, de importância

primordial para os espanhóis e por-

tugueses quando se fizeram novos

donos dèste país. As pesquisas

em aguas amazônicas começaram,

pois, com o mapeamento dos cursos

de água cujo aperfeiçoamento con-

cluiu-se somente no tempo atual

com a elaboração dos mapas mo-

dernos, baseados em aerofotogra-

fias.

Porém, já os cronistas da primei-

ra expedição, da de Pedro Teixeira

em 1637/38, a qual planejadamen-

te subiu e desceu o Amazonas des-

de a foz até os Andes, Acuna e

Rojas, eram observadores de uma

visão tão vasta que êles notaram,

em princípio, quase todos os aspec-

tos que as águas amazônicas ofe-

receram, nos tempos posteriores, à

curiosidade científica dos homens.

Além da cartografia — e da hidro-

biologia que se tratará, neste sim-

pósio, numa conferência especial

— aqueles relatórios já tocaram

nos seguintes complexos:

Anastomoses entre diferentes siste-

mas fluviais (pela menção do

conexo entre o Rio Negro e um

rio que desemboca no oceano) ;

Morfologia dos rios (pelas indica-

ções sôbre larguras e profun-

didades) ;

Tipos de rios (pela descrição da

água preta do Rio Negro);

Peculiaridade da Várzea no conjun-

to da paisagem amazônica (pe-

la observação da fertilização

periódica pelas inundações

anuais) ;

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Volume 3 (Limnologia)

45

Conteúdo em nutrimentos e Ecolo-

gia da região inteira (pelo jul-

gamento — aliás errôneo — da

qualidade dos solos) .

Anastomoses entre rios de siste-

mas potâmicos diferentes foram

provados cientificamente pela pri-

meira vez por Humboldt quando

navegou pelo Cassiquiare. Hoje co-

nhecem-se mais ligações entre o

sistema amazônico e outros siste-

mas fluviais sul-americanos.

Na Morfologia dos rios amazôni-

cos, dois problemas destacam-se no

interêsse dos geógrafos e limnólo-

gos: os perfis dos leitos dos gran-

des rios, e os cursos inferiores, la-

goiformes, de muitos afluentes. As

primeiras determinações de pro-

fundidades grandes (na “gargan-

ta” de Óbidos, Spix & Martius en-

contraram 83 m) foram provadas e

até superadas por recentes sonda-

gens de éco, no rio Negro (~ 100m)

e no Baixo Amazonas; o fundo do

leito do Baixo Amazonas revelou-se

como consistindo de material que

se desloca em forma de “ripple-

marks” gigantescos, de verdadei-

ras dunas. Os cursos inferiores de

muitos afluentes, alargados despro-

porcionalmente e transformados

até em “lagos de terra firme*”, re-

conheceram-se, primeiramente por

Denis, como sendo “vales afoga-

dos”; limnològicamente, estas se-

ções de cursos de rios assemelham-

-se mais a lagos do que a rios .

Como tipos de rios amazônicos

estabeleceram-se os de rios de água

“branca” (barrenta), de água cla-

ra (transparente) e de água preta.

Os tipos dependem de fatores de

paisagem nas regiões das cabecei-

ras (relêvo, clima, cobertura vege-

tal), porém não são absolutamen-

te distintos um do outro e perma-

nentes mas podem ser ligados por

tipos intermediários, ou até podem

variar periodicamente ou casual-

mente para o mesmo rio.

A Várzea do Baixo Amazonas, tão

diferente, na qualidade e fertilida-

de do solo e na vegetação, da ter-

ra firme, explica-se como produto

de colmatagem geologicamente re-

cente do vale afogado do Amazo-

nas, sendo desta forma, segundo

Fittkau, uma prolongação, ao lon-

go do curso da água branca do

Amazonas, do material sedimentar

da faixa pré-andina, um apêndice

à mesma através da Baixa Amazô-

nia. Êste material sedimentar da

faixa pré-andina difere, pela ori-

gem geológica e pela idade, nas

suas qualidades pedológicas, dos so-

los das camadas do arqueano e do

terciário da terra firme do Baixo

Amazonas.

O conteúdo em nutrimentos con-

cluiu-se de análises químicas de

águas de rios e igarapés e de água

freática. Já as primeiras análises

feitas por Katzer revelaram uma

surpreendente pobreza em sais dis-

solvidos. Análises posteriores de

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Atas do Simpósio sôbre a Biota Amazônica

águas de diferentes zonas geológi-

cas provaram esta pureza química

geral, havendo somente poucas ex-

ceções, p. e. nas faixas do carbo-

nífero. Tal pobreza das águas cor-

rentes é uma expressão de pobre-

za correspondente, dos solos nas

cabeceiras, nos mesmos iônios, en-

tre êles também em nutrimentos

para a vegetação. O quimismo das

águas, pois, mostrou-se como exce-

lente indicador para ganhar uma

primeira idéia também da Ecologia

da paisagem amazônica, especial-

mente do metabolismo de nutri-

mentos do ecossistema da terra fir-

me amazônica com a floresta alta

pluvial.

REFERENCES

Acuna, C., 1941, Descobrimento do rio

das Amazonas. Trad. e anot. por

C. de Melo Leitão. 294 pp., S. Paulo,

Cia. Ed. Nacional. (Biblioteca Pe-

dagógica Brasileira. Sér. 5.: Brasi-

liana, v. 203.)

Andrade, G. O. O., 1958, Furos, paranás e

igarapés; análise genética de al-

guns elementos do sistema pota-

mográfico amazônico. Rev. Geogr.

Inst. Pan Amer. Geogr. Hist., Rio

de Janeiro, 22 (48) : 3-36. Boi. Ca-

rioca Geogr., Rio de Janeiro, 9

(3/4): 15-50.

Braun, R., 1952, Limnologische Unter-

suchungen an einigen Seen im

Amazonasgebiet. Schw. Zeits. Hy-

drol., Basel, 14 (1) : 1-128.

Carvajal, G„ 1941, Descobrimentos do

rio das Amazonas. Trad. e anot.

por C. de Melo Leitão. 294 pp , S.

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teca Pedagógica Brasileira, Sér. 5.:

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Clauss, O., 1866, Bericht über die

Schingu-Expedition im Jahre 1884.

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129-134.

Coudreau, H. A., 1897, Voyage au Ta-

pajós, 28 juillet 1895 — 7 janvier

1896. 215 pp., Paris, A. Lahure.

Coudreau, H. A., 18S7, Voyage ao Xingú,

30 mai 1896 — 26 octobre 1896. 230

pp., Paris, A. Lahure.

Coudreau, H. A., 1897, Voyage au To-

cantins — Araguaya, 31 décembre

1896 — 23 mai 1897. 330 pp., Paris,

A. Lahure.

Coudreau, H. A., 1899, Voyage au Ya-

mundá, 21 janvier 1899 — 27 juin

1899. 163 pp., Paris, A. Lahure.

Coudreau, H. A., 1900, Voyage au Trom-

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Coudreau, O., 1901, Voyage au Cuminá,

20 avrll 1900 — septembre 1900. 190

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Coudreau, O., 1903, Voyage au Rio

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1901. 114 pp„ Paris, A. Lahure.

Coudreau, O., 1903, Voyage à la Ma-

puéra, 21 avril 1901 — 24 décembre

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Coudreau, O., 1903, Voyage au Maycurú,

5 juin 1902 — 12 janvier 1903. 151

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Denis, P., 1927, UAmérique du Sud. Le

Brésil, chap. VII, L’Amazonie. Col.

Géogr. Univers., XV, 2ème partie.

Paris.

cm

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Volume 3 (Limnologia)

47

EGLER, w. A. & SCHWASSMANN, H. O.,

1962, Limnological studies in the

Amazon Estuary. Boi. Mus. Para-

ense Emílio Goeldi, n. s.. Avulsa 1:

2-25.

EGLER, W. A. & SCHWASSMANN, H. O-,

1964, Limnological studies in the

Amazon Estuary. Verh. Internat.

Verein. Limnol., 15: 1059-1066.

Fittkau, E. J., 1964, Remarks on Limno-

logy of Central-Amazon rain-fo-

rest streams. Verh. Internat. Verein.

Limnol., 15: 1092-1096.

Gessner, F„ 1957, Die Beziehung zwis-

chen pH und elektrolytischem Leit-

vermõgen in den Gewâssern der

Rio Negro-Gebietes. Naturwissen-

schaften, 44 (8): 258-259.

Gessner, F., 1960, Untersuchungen

über den Phosphathaushalt des

Amazonas. Internat. Rev. ges. Hy-

drobiol., 45 (3) : 339-345.

Gessner, f., 1960, Ensayo de una com-

paracion quimica entre el Rio

Amazonas, el Rio Negro y el Ori-

noco. Acta Cient. Venezolana, 11

(2): 3-4.

Gessner, f., 1960, Limnologische Unter-

suchungen am Zusammenflufi des

Rio Negro und des Amazonas (So-

limoes). Internat. Rev. ges. Hydro -

biol, 45 (1) : 55-79.

Gessner, f., 1961, Der Sauerstoffhaush-

halt des Amazonas. Internat. Rev.

ges. Hydrobiol, 46 (4) : 542-561.

Gessner, f„ 1962, Der Elektrolytgehalt

des Amazonas. Arch. Hydrobiol., 58

(4) : 490-499.

Gessner, p., 1964, The limnology of

tropical rivers. Verh. Internat.

Verein. Limnol., 15: 1090-1091.

Gourou, P., 1949, Observações geográ-

ficas na Amazônia. I. pt. Rev. Bras.

Geogr., 11 (3) : 356-408.

Hartt, C. F., 1897/1898, A região de

Breves (Trabalhos restantes iné-

ditos da Commissão Geológica do

Brasil relativos à Geologia e Geo-

grafia physica do Baixo Amazonas,

2). Boi. Mus. Paraense Hist. Natur.

Ethnogr., Belém, 2: 173-181.

Huber, J., 1903, Contribuição à geogra-

phia physica dos furos de Breves e

da parte Occidental de Marajó. Boi.

Mus. Paraense (Museu Goeldi; ,

Belém, 3 (1900-1902) : 447-498.

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noctial—Gegenden des neuen Con-

tinents. In deutscher Bearbeitung

von Hermann Hauff. Stuttgart, J.

G. Cotta’scher Verlag.

Katzer, F„ 1897, Das Wasser des un-

teren Amazonas. Sitz. bõhm. Ges.

Wiss. Math.-naturw. cl., 17: 1-38.

Katzer, F., 1903, Grundzüge der Geolo-

gie des unteren Amazonasgebietes

(des Staates Pará in Brasilien).

298 pp., Leipzig, Max Weg.

Klinge, H., 1965, Podzol Soils in the

Amazon Basin. J. Soil Sei., 16: 95-

-193.

Klinge, H. & Ohle, W., 1964, Chemical

properties of rivers in the Ama-

zonian area in relation to soil con-

ditions. Verh. Internat. Ver. Lim-

nol., 15: 1067-1076.

La Condamine, c. M., 1775, Relation

abrégée d’un voyage jait dans

1’interieur de VAmérique Méridio-

nale, depuis la côte de le Mer du

Sud, jusqu’aux côtes du Brésil &

de la Guiane, en descendant la

rivière des Amazones... par M. de

cm

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48

Atas do Simpósio sôbre a Biota Amazônica

la Condamine . . . Avec une carte

du Maragnon, ou de la rivière des

Amazones, levés par le même. 216

pp., Paris, Pissot.

Le Cointe, P., 1911, Carte du Bas Ama-

zone de Santarém à Parintins, 1;

250 000 . Paris, Librairie Armand

Colin.

Le Cointe, P., 1945, O Estado do Pará.

A terra, a água e o ar. X -f 305 pp.,

São Paulo, Companhia Editora Na-

cional.

Marlier, G., in press, Étude sur les iaes

de l’Amazonie Centrale. Cadernos

da Amazônia, Manaus, 5

Marlier, G., in press, Ecological studies

on some lakes of the Amazon valley.

Amazoniana.

Matos, F.J.G., 1937, Les idées sur

la physiographie sud-américainè.

Communication présentée au III"

Congrès International d’Histoire

des Sciences — Lisbonne, 1934 (Ex-

trait du livre des “Actes, Confé-

rences et Communications du

Congrès”, publié à Lisbonne l’an

1936), Lisboa: 391-440.

Oltman, R E , Sternberg, H. O. R.,

Ames, F. C. & Davis, Jr., L. C., 1964,

Amazon River Investigations — Re-

connaissance Measurements of July

1963. Washington, Geological Sur-

vey Circular 486, III: 1-15.

Pardé, M., 1936, Les variations saison-

nières de 1’Amazone. Ann. Géogr.,

Paris, 45 (257) : 502-511.

Pardé, M., 1964, Fleuves e Rivièics. 224

pp., Paris, Librairie Armand Colin

Pinto, A. O., 1930, Hydrographia do

Amazonas e seus affluentes. 2 vol.,

XII -f 438 pp., 25 maps., Rio de

Janeiro, Imprensa Nacional.

Rojas, A., 1941, Descobrimentos do rio

das Amazonas. Trad. e anot. por

C. de Meio-Leitão. 294 pp., (Biblio-

teca Pedagógica Brasileira. Sér.

5: Brasiliana, v. 203.)

Sioli, H„ 1949, O Rio Cuparl. I. Topo-

grafia e Hidrografia. Boi. Técn.

Inst. Agr. Norte, Belém-Pará, 17:

1-50.

Sioli, H., 1950, Das Wasser im Amazo-

nasgebiet. Forsch. Fortschr., 26,

21/22: 274-280.

Sioli, H., 1951a, Sôbre a sedimentação

na Várzea do Baixo Amazonas. Boi.

Técn. Inst. Agr. Norte, Belém-Pará,

24: 45-65.

Sioli, H., 1951b, Zum Alterungsprozef)

von Flüssen, und Flufitypen im

Amazonasgebiet, Arch. Hydrobiol.,

45: 267-283.

Sioli, H„ 1954a, Beitrâge zur regionalen

Limnologie des Amazonasgebietes.

II. Der Rio Arapiuns, ein Gewásser

des Tertiàr gebietes (Pliozân) , Serie

der “Barreiras”, Unter-Amazo-

niens. Arch. Hydrobiol., 49 (4) :

448-518.

Sioli, H., 1954b, Gewàsserchemie und

Vorgànge in den Bõden im Amazo-

nasgebiet. Naturwissenschaften, 41

(19): 456-457.

Sioli, h., 1955, Beitrâge zur regionalen

Limnologie des Amazonasgebietes.

III über einige Gewásser des

oberen Rio Negro-Gebietes. Arch.

Hydrobiol., 50 (1) : 1-32.

Sioli, H., 1956a, über Natur und Mensch

im brasilianischen Amazonasgebiet.

Erdkunde, 10 (2) : 89-109.

Sioli, H., 1956b, O Rio Arapiuns. Estu-

do de um corpo d’água da região

cm

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49

do terciário, série das barreiras, do

Baixo Amazonas. Boi. Técn. Insz.

Agr. Norte, Belém-Pará, 32: 1-115.

Sioli, H., 1956c, As águas da região do

Alto Rio Negro. Boi. Técn. lnst.

Agr. Norte, Belém-Pará, 32: 117-

-155.

Sioli, H., 1957a, Beitràge zur regionalen

Limnologie des Amazonasgebietes.

IV. Limnologische Untersuchungen

in der Region der Eisenbahnlinie

Belém — Bragança (“Zona Bragan-

tina”) im Staate Pará, Brasnien

Arch. Hydrobiol, 53 (2) : 161 - 222 .

Sioli, h., 1957b, Valores de pH de águas

amazônicas. Boi. Mus. Paraense

Emílio Goeldi, Geologia, 1: 1-37.

Sioli, h., 1957c, Sedimentation im Ama-

zonasgebiet. Geol. Rundschau, 45

(3) : 608-633.

Sioli, h., 1957d, Die “Fruchtbarkeit”

der Urwaldbõden des brasilianis-

chen Amazonasgebietes und ihre

Bedeutung für eine zukunftige

Nutzung. Staden-Jahrbuch, S. Pau-

lo, 5: 23-36.

Sioli, h., 1960, Pesquisas Limnológicas

na Região da Estrada de Ferro de

Bragança, Estado do Pará, Brasil.

Boi. Técn. Inst. Agr. Norte, Belém'

Pará, 37: 1-91.

Sioli, 1961, Landschaftsõkologischer

Beitrag aus Amazonien. Natur u.

Landschaft, 36 (5) : 73-77.

Sioli, h„ 1963, Beitràge zur regionalen

Limnologie des brasilianischen

Amazonasgebietes. V. Die Gewàssei

der Karbonstreifen UnteramazO'

niens (sowie einige Angaben übei

Gewásser der anschlies senden De'

vonstreifen) . Arch. Hydrobiol., 59

(3): 311-350.

Sioli, H., 1964a, Die natürlichen Ge-

wàsser der unteramazonischen

Karbonstreifen ais Indikatoren füi

Untergrund- und Bodenverhált'

nisse im Hinblick auf zukünftige

landwirtschaftliche Nutzung. C.

R. XVIIIe Congrès International de

Géographie, Rio de Janeiro, 1956,

II: 390-398.

Sioli, H„ 1964b, General features of

the Limnology of Amazônia. Verh.

Internat. Verein. Limnol., 15: 1053-

-1058.

Sioli, H„ 1965a, Zur Morphologie des

Flufibettes des Unteren Amazonas.

Naturwissenschaften, 52 (5) : 104.

Sioli, h., 1965b, Bemerkungen zu den

Fundorten. In: Scott, Arthur M. +.

Rolf Grõnblad + and Hannah

Croasdale: Desmids from the Ama-

zon Basin, Brazil, collected by Dr.

H. Sioli. Acta Bot. Fenn. 69: 5-18.

Sioli, H., 1965c, A Limnologia e a sua

importância em pesquisas da Ama-

zônia. Amazoniana, 1 (1) : 11-35.

Sioli, H., 1965d, Bemerkungen zur Ty-

pologie amazonischer Flüsse. Ama-

zoniana, 1 (1): 74-83.

Sioli, H„ 1966, General features of the

Delta of the Amazon. — Humid

Tropics Research — Scientific Pro-

blems of the Humid Tropical Zone

Deltas and their Implications .

Proceedings of the Dacca Sympo-

sium. UNESCO: 381-390.

Sioli, H. & Klinge, H., 1961, Übei

Gewásser und Bõden des brasilia-

nischen Amazonasgebietes. Die

Erde, 92 (3) : 205-219.

1 — 37 121

cm l

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Atas do Simpósio sôbre a Biota Amazônica

Sioli, H. & Klinge, H., 1962, Solos,

tipos de vegetação e águas na

Amazônia Brasileira. Boi. Mus. Pa-

raense Emílio Goelãi, Avulsa, 1:

27-41.

Soares, L. C., 1959, Hidrografia. In:

Geografia do Brasil, I, Grande Re-

gião Norte, Rio de Janeiro, IBGE,

Conselho Nacional de Geografia:

128-194.

Spix, J. B. & Martius, K. F. P., 1823-

1831, Reise in Brasilien auf Be-

fehl Sr. Majestát Maximilian Jo-

seph I., Kõnigs von Bayern, in den

Jahren 1817 bis 1820 gemacht und

beschrieben von dr. Joh. Bapt. von

Spix . . . und dr. Cari Friedr. Phil.

von Martius. München, Gedruckt

bei M. Lindauer.

Sternberg, H. 0’R., 1950, Vales tectô-

nicos na planície amazônica? Rev.

Br as. Geogr., Rio de Janeiro, 12

(4): 511-534.

Sternberg, H. 0’R., & Pardé, M., 1965,

Information d’origine récente sur

les débits monstrueux de 1’Amazo-

ne. Actes du 89' Congrès National

des Sociétés Savantes, Lyon 1964:

189-195.

Tastevin, C., 1929, Le delta du Japurá

et le Piuriny. Géographie, Paris, 51:

280-298.

U.S. Department of the Interior Geo-

LOGICAL SURVEY INFORMATION OFFICE,

1964: Amazon River Investigation

1963, Measuring a Mighty River-

Hydrologists tackle the Amazon.

Washington, Geological Survey,

Forrester 343-4646: 9 pp.

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Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 51-62 — 1967

COMPARATIVE LIMNOLOGY OF THE STREAMS OF

FLORIDA AND THE UPPER AMAZON BASIN

WILLIAM M. BECK, JR.

Florida State Board of Health, Jacksonville, U.S.A.

(With 7 text-figures)

The long history of lake limno-

logy has made possible compara-

tive regional studies based on a

period of many years. A typical

example of this is the expedition

made by Brundin (1956) to the

high mountain lakes of the south

ern Andes for the purpose of

comparing these lakes with the

equivalent lakes of Northern Eu-

rope. As was pointed out by Beck

(1956), limnology has been taught

in North America largely in

schools located in lake regions with

a consequent lack of emphasis or

even minor efforts with regard to

streams. Most studies of streams

in North America have been made

by federal or state agencies for the

purpose of determining water qua-

üty in connection with pollution

abatement, fisheries resources, the

effects of impoundments, etc. Most

of this work either ends up in the

files of the aforementioned govern-

mental agencies or is occasionally

distributed in the form of mimeo-

graphed reports. These reports are

frequently an accumulation of re-

sults gathered individually by en-

gineers, chemists, bacteriologists,

and biologists with the result

that most lack the integrated ap-

proach of a true limnological sur-

vey, geology being the one factor

most frequently neglected.

The following quotation from

Hutchinson (1963: 689) reflects to

a large degree what has been stat-

ed above: “The whole subject of

rivers, now ordinarily though not

philologically subsumed in limno-

logy, appears to him [the author]

as a marvelous foreign territory ex-

plored by workers whose audacity

is admirable in view of the diffi-

culty of getting a theoretical grasp

of the subject.”

The many excellent publications

of Sioli, Fittkau, and Klinge &

Ohle give a rather thorough

understanding of the limnology, in

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Atas do Simpósio sôbre a Biota Amazônica

its total aspect, of the streams of

Amazônia. My own work with the

streams of Florida has extended

over a period of 25 years and is

sufficient, I believe, for a compari-

son of the streams of the two areas

in question.

I wish to express my sincere gra-

titude to the Association for Tropi-

cal Biology and the National Academy

of Sciences for making possible my

participation in this Symposium.

FLORIDA AND ITS STREAMS

The geology of the State is of

primary importance in Florida lim-

nology. Florida is underlain enti-

rely by limestones, marls and sands

of tertiary and quarternary origin

which is very similar to the geo-

logical background of certain areas

of Amazônia. One striking diffe-

rence is the presence of considera-

ble quantities of dissolved phospha-

Fig. 1 — Florida (1 — Perdido River; 2 — Chipola River; 3 St Marks River-

4 — Aucilla River; 5 — Santa Fe River).

cm

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53

Fig. 2 — Alapaha River, during normal or low flow.

tes in most of the waters of Flo-

rida.

With the exception of the ex-

treme western panhandle, Florida

is an area of Karst topography ty-

pified by innumerable sink-holes,

lakes of solution origin, disappear-

ing rivers (Figs. 1-3), numerous

springs, and areas with no streams

at all. According to the geologists,

Pleistocene deposits due to chan-

ges in sea levei have concealed a

Karst topography even more

striking than that of the classical

region.

It is in the area of topography

that another striking regional dif-

ference occurs. Florida has a ma-

ximum elevation of about 400 feet

with stream gradients in some

areas sufficient for the formation

of rapids but no surface water-

falls over four feet in height.

According to Cooke (1963), Flo-

rida is divided distinctly into five

topographic regions (Fig. 4). An

additional topographic area was

delineated by Beck & Beck

(1959) and designated as the Re-

lict Area. This area is one of spe-

cial interest to the biologist as it

consists of cool, shaded ravines in

which are found many species of

plants and animais representing

either species confined to that area

or relict populations of species not

found elsewhere south of the Pied-

mont of northern Geórgia.

The highest elevations in Florida

occur in the Central Highlands and

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Atas do Simpósio sôbre a Biota Amazônica

the Western Highlands while the

Coastal Lowlands occupy a major

portion of the State of Florida and

extend entirely around the coast,

ranging in width from a very nar-

row strip in the extreme western

panhandle to their greatest width

in the Southern portion of the Sta-

te where the Southern third of the

peninsula is entirely lowland. The

Tallahassee Hills is an area of rol-

ling hills of high pineland and

hardwod forests. The term “Ma-

rianna Lowlands” is a misnomer

since the area is only slightly low-

er in general elevation than the

two adjacent areas. It is, however,

one of the most interesting areas

with some of the most striking

Karst topography in the State and

has the only caverns developed for

public use.

The climate of Florida ranges

from south temperate in the north-

western panhandle to tropical in

the Keys. According to Provost

(undated manuscript), no part of

the mainland of Florida is truly

tropical despite the presence of

many tropical plants and animais

(Fig. 5).

Fig. 5 shows several items of spe-

cial interest with regard to the cli-

mate of Florida. Foremost is the in-

fluence of the proximity of the

Gulf Stream to the east coast, ex-

tending the subtropical and Flori-

dian regions much farther up the

east coast than they extend up

TPi

ift-

Fig. 3 — Alapaha River, in flood.

the west coast. The subtropical re-

gion delineates the range of the

large bromeliad, Tillandsia utri-

culata, and the West Indian land

crab, Cardisoma guanhumi.

The 58.° January isotherm repre-

sents roughly a zone of intergrada-

tion between southeastern and Flo-

ridian, subspecies in the field of

herpetology. Thus in the Floridian

region are found most of the spe-

cies and subspecies of endemic rep-

tiles and amphibians. The 64.° iso-

therm crosses another area of in-

tergradation between Floridian

and South Floridian subspecies of

reptiles (Carr, 1940).

Figure 6 is a climatograph based

on mean monthly temperatures

and rainfall for the Miami (sub-

cm

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Volume 3 (Limnologia)

55

tropical) area. It will be noted that

the climatograph is an almost ty-

pical example of a tropical annual

cycle involving a hot, rainy season

and a cool, dry season. Bates

(1864: 31) makes the following

statement with regard to the cli-

mate of Belém: “A little differen-

ce exists between the dry and wet

seasons; but generally, the dry sea-

son, which lasts from July to De-

cember, is varied with showers,

and the wet, from January to June,

with sunny days.”

COMPARATIVE LIMNOLOGY

Sioli (1964, 1965) presents ex-

cellent summaries of the limnolo-

gical features of Amazónia in

which he divides the streams of the

area into three basic types. Beck

(1965) lists five different types of

streams found in Florida. These

classifications are listed and com-

pared in Table 1.

The “white” water stream of

Sioli (1964: 1054) is quite similar

to the larger rivers of Beck. Ran-

Mfj

$1

Q Coastal Lowlands

O Marianna Lowlands

A Relict Areas

Fig. 4 — Topographic regions o] Cooke.

2 3

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Atas do Simpósio sôbre a Biota Amazônica

TABLE 1

Stream Classification

Sioli

pH

Beck

pH

1. “Wliite” water..

6.5 — 6.9

6 5_6 9

2. “Clear” water

6.4 — 6.65

Calcareous streams

7.0 — 8.2

3 . “Black” water

3.8 — 4.9

Sand-bottomed streams

5.7— 7.4

4. “Black” water

5.

Swamp-&-bog streams

Canais of southeastern Florida

3.8 — 6.5

ges of pH are identical, probably

by coincidence since the figures gi-

ven for the larger rivers of Florida

represent only one stream. With

the exception of the St. Johns Ri-

ver which is unique (Numeral 6,

Fig. 7), these larger rivers are

quite similar chemically and phy-

sically. The values selected for

comparative purposes in Table 1

are for the Apalachicola River (Nu-

meral 3, Fig. 7) which has been

studied more thoroughly than the

others. Larger rivers, such as the

Escambia, Choctawhatchee, Apa-

lachicola and Ochlocknee, are all

interstate streams rising in the

hills of Alabama and Geórgia, and

all are consistently turbid due to

a suspension of Montmorillonite

clay giving these waters a whitish

or slightly yellowish appearance

and reducing light penetration to

a major degree.

The second category of Sioli, the

“clear” water stream, is some-

what comparable to the calcareous

stream of Beck although uniformly

lower in pH. The calcareous stream

originates entirely, or to a major

degree, from springs although ge-

nerally there are lateral contribu-

tions of colored swamp or lake

drainage. Consequently, though

the water is very transparent, it

often has a yellowish color.

The “black” water stream of

Sioli is apparently quite similar to

both the sand-bottom and the

swamp-and-bog streams in Flori-

da (Table 1). Although I consider

these two types of Florida streams

distinctive, the only real differen-

ce is found in the extremely

low velocity of the swamp-and-bog

stream and in Chemical differences

associated with this lowered velo-

city (extremely low pH, alkalinity,

hardness; extremely high color due

to “humic acids”) . Despite the

higher pH limits of the sand-bot-

tom stream in Florida, it is still

comparable to the “black” water

stream of Sioli due to its high

color .

The canais of southeastern Flo-

rida are listed in the publication of

Beck (1965) as a stream type al-

though they are not streams in any

true sense of the word. At most ti-

mes these canais have a distinct

cm

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Volume 3 (Limnologia)

57

Fig. 5 — Climatic regions of Provost.

seaward flow although at other ti-

mes there may be no movement of

the water at all. They are listed as

a stream type simply because they

are all that remain of the former

streams along some 140 miles of

the coast of southeastern Florida.

It would thus appear that both

Amazónia and Florida possess

three basic, comparable types of

streams with a certain amount of

intergradation among the dif-

ferent types.

Fittkau (1964) discusses limno-

logical features of the rain-forest

streams of the upper Rio Negro ba-

sin. The most unusual feature of

these streams is their remarkably

low concentration of dissolved elec-

trolytes. The stream forming the

western boundary of Florida, the

Perdido River (Numeral 1, Fig. 1),

is quite similar chemically to the

rain-forest streams. Table 2 compa-

res certain factors in these streams.

It will be noted that these streams

cm l

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Louisianian

Floridian

58

Atas do Simpósio sôbre a Biota Amazônica

are distinctly acid, may have very

high free carbon dioxide content

and are very low in hardness, al-

kalinity, and chlorides. Fittkau

attributes the paucity of life in the

rain-forest streams to the extreme

poverty of electrolytes and the lack

of light due to the dense rain-fo-

rest canopy. While the Perdido Ri-

ver is neither as densely shaded nor

quite as low in dissolved eleetroly-

tes, it is not a particularly produc-

tive stream. In areas where vege-

tation occurs, growths of aquatic

plants, which may support quite a

rich and varied invertebrate fauna,

are generally confined to small

areas. Most of the stream bottom

consists of coarse, shifting sand

and is inhabited only by the larger

species of burrowing dragonflies

and mayflies.

At this time no attempt will be

made to compare the biology of

the streams of Amazônia and Flo-

rida due to the fact that relatively

little has been published thus

far concerning the biology of the

Mean Monthly

Temperature °F

Fig. 6 — Climatograph : Miami area.

Volume 3 (Limnologia)

59

Fig. 7 — Florida, larger rivers: (1 — Escarniria River; 2 — Choctawhatchee

River; 3 — Apalachicola River ; 4 Ochlocknee River; 5 — Suwannee

River; 6 — St. Johns River).

streams of Amazónia despite ex-

tensive study of the area performed

especially by biologists from Hy-

drobiologische Anstalt der Max-

Planck-Gesellschaft, and also be-

cause the biota of the streams of

Florida has not been thoroughly

studied.

In December, 1965, following se-

veral months spent in Amazónia,

Dr. Fittkau was our guest in north-

ern Florida for a brief period.

During this time we spent one day

examining streams in our area,

mainly sampling for invertebrates.

We were truly astonished at the

number of different genera in di-

verse groups of invertebrates that

Dr. Fittkau could identify imme-

diately. Many of these, including

the Odonata, Trichoptera, Coleop-

tera, Plecoptera, Ephemeroptera,

60

Atas do Simpósio sôbre a Biota Amazônica

mollusks and other smaller groups,

possessed genera which I did not

realize existed in Amazônia. Al-

though Dr. Fittkau has studied the

chironomid fauna of Amazônia for

some years, and my wife and I have

conducted similar studies in Flori-

da, too little has been published to

support any significant compari-

sons at present.

CONCLUSIONS

Both Florida and Amazônia have

three similar, basic types of

streams. Although significant dif-

ferences exist among the three

stream types of the two areas in

question, there are enough Chemi-

cal and physical similarities to sug-

gest that the approach of compa-

rative limnology is worthwhile. In

both areas, intergradation exists

among all stream types.

The most interesting features of

the streams of both areas are the

factors in which they differ. Fore-

most among these differences is

the high dissolved nutrient concen-

trations normally found in the wa-

ters of Florida in contrast with the

extremely low concentrations in

the streams of Amazônia. Second

is the significantly higher velocity

of the upper Amazon streams, sup-

porting groups of invertebrates

that have not been found thus far

in Florida. One type of stream not

found in Florida is the rain-forest

stream described by Fittkau.

These streams are so covered by a

canopy of trees that only 0.5 to 1

percent of the total solar radiation

at noon reaches them. The Perdido

River, compared with the rain-fo-

rest streams in Table 2, is quite

similar in some respects to those

streams.

It is my belief that principies

exist in stream limnology just as

they do in the limnology of lakes.

Unfortunately, it requires more ef-

fort to discover them. Ever since

the origin of the concept of a lake

as a microcosm, the possibilities

inherent in the study of a more or

less closed system have appealed

to a great many students. On the

other hand, streams apparently

have had less appeal, perhaps due

to the extensive variation of limno-

logic factors in regard to both time

and space. This lack of apprecia-

tion for or interest in streams is

reflected in the recent enactement

of the Wild Rivers legislation by

the United States government

making rivers the last natural re-

sources to be recognized and pre-

served in their natural state for

the benefit of future generations.

Already we have developed a

specialized terminology with re-

gard to flowing waters including

such terms as rheophile, rheobiont,

Spritzwasserarten, etc. in addition

to many generic names of aquatic

organisms beginning with Rheo. or

Potamo. Many special items of

Volume 3 (Limnologia)

61

TABLE 2

Comparison of Low Electrolyte Waters

Upper Rio Negro

Factors

Perdido River

4.1 —5.2

pH

5.3 — 5.5

4.4 — 91.5

free C0 2 mg/L

60 — 150

0 — 0.65° DGH

hardness

5 — 8 mg/L

0 — 3

chlorides mg/L

4 — 8

0 — 0.5 NO 3 -X

0.1 nh 3 -n

0 — 7

bicarbonates mg/L

10 — 15

equipment have been developed

specifically for work in streams:

the fresh water current meter, the

electronic oxygen probe (especial-

ly the type which measures oxygen

only in waters with a minimum ve-

locity of 1 foot per second), the

Brundin net, the Catherwood dia-

tometer, the Hestler-Dendy plate

sampler and the Tebo sampler .

Both the specialized terminology

and specialized equipment reflect

distinctive aspects of a specialized

field and suggest rather precisely

where to look for possible univer-

sal principies of stream behavior.

The following items are offerred as

being basic to the formation of any

principies of stream limnology:

1 .

2 .

A stream is a body of water of

geographical significance typi-

fied by unidirectional flow.

A stream is highly variable in

its physical, Chemical and bio-

logical characteristics with res-

pect to both time and space.

3. These variations are cyclic in

nature, the variations depend-

ing on both geographic loca-

tions and climatic differences.

4 . A stream is a function of its en-

tire drainage basin.

5. Water is the most extraordina-

ry of all compounds known to

Science. Whether in lakes or in

streams or indeed in the oceans

themselves, water reacts every-

where to the same laws of phy-

sics and chemistry regardless of

the Container in which it is

found.

SUMMARY

Streams of the areas in question

have many features in common.

The basic classification of stream

typology as presented by Sioli

(1964, 1965) does not differ great-

ly from the classification of Flo-

rida streams as proposed by Beck

(1965).

Although there are some strik-

ing similarities in the streams of

cm

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10 11 12 13 14 15 16

62

Atas do Simpósio sôbre a Biota Amazônica

the two areas in question, it is in

the differences — Chemical, physi-

cal, biological, and geological —

that we find the most striking

and informative features. A compa-

rison of both the common and the

distinctive features may contribu-

te significantly to a better under-

standing of comparative regional

limnology and further development

of that branch of limnology devot-

ed to the study of flowing waters.

Probably more has been publish-

ed on the limnology of the Upper

Amazon than on all the streams

of Florida combined. This literatu-

re makes possible comparisons bet-

ween streams of an area in which

I have worked for many years

and streams of an area which I

have never seen. The writings of

Sioli, Ohle, Klinge, and Fittkau, in

addition to correspondence and

personal contact with these wor-

kers, have further contributed to

an understanding of mutual and

unique problems. Dr. Fittkau spent

several days with us in December,

1965, and we were astonished at

his familiarity with our local

stream faunas. He recognized

many genera of aquatic inverte-

brates that we did not realize exist-

ed in South America.

REFERENCES

Bates, H. W., 1864, The naturalist on

the River Amazon. 407 pp., J. M.

Dent and Sons, Ltd., London.

Beck, E. & Beck, Jr., W. M„ 1959, A

checklist of the Chironomidae (In-

secta) of Florida (Diptera: Chiro-

nomidae) . Buli. Fia. State Mus.,

4 (3) : 85-96.

Beck, W. M., JR-, 1965, The streams of

Florida. Buli. Fia. State Mus., 10

(3): 91-126.

Brundin, L., 1956, Die bodenfaunistis -

chen Seetypen und ihre Anwenã-

barkeit auf die Suãhalbkugel. Ins-

titute of Freshwater Research,

Drottningholm. Rep. N.° 37: 186-

235.

Carr, A. F., JR., 1940, A contribution to

the herpetology of Florida. XJniv.

Fia. Publ., Biol. Sei. Ser., 3(1): 1-

118.

Cooke, C. W„ 1939, Scenery of Florida

interpreted by a geologist. Fia.

State Dept. Conserv., Geol. Buli.,

17: 1-118.

Fittkau, E„ J., 1964, Remarks on lim-

nology of central-Amazon rain-

-forest streams. Verh. Internatl

Verein. Limnol., 15: 1092-1096.

Hutchinson, G. E., 1963, The prospect

bejore us; in Limnology in North

America, ed. David G. Frey. Univ.

Wisconsin Press: 683-690.

Klinge, H. & Ohle, W., 1964, Chemical

properties of rivers in the Ama-

zonian area in relation to soil con-

ditions. Verh. Internatl. Verein.

Limnol., 15: 1067-1076.

Provost, M. W., Mosquitoes and climate

in Florida, unpublished manus-

cript: 1-15.

Sioli, H., 1964, General features of the

limnology of Amazônia. Verh. In-

ternatl. Verein. Limnol., 15: 1053-

-1058.

Sioli, H., 1965, Bemerkung zur Typo-

logie amazonischer Flusse. Amazo-

niana, 1: 74-83.

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 63-82 — 1967

LA SUPERFAMILIA UNIONACEA EN LA

CUENCA AMAZÔNICA

ARGENTINO A. BONETTO

Instituto Nacional de Limnologia,

Santo Tomé (Santa Fe), Argentina

(Con 10 figuras en ei texto)

El conocimiento sistemático de

las Nayades de la cuenca dei Ama-

zonas resulta bastante pobre aun

si lo comparamos con el que se po-

see respecto al resto de América

neotrópica. Tal situación no depen-

de tanto de la falta de trabajos dei

tipo corriente sino, por el contra-

rio, de la existência de una gran

cantidad de tipos descriptos sobre

la base de unos pocos ejemplares,

muchas veces de pobre conserva-

ción, con referencias geográficas

imprecisas cuando no con desco-

nocimiento total de su procedência.

A esto debe sumarse la falta de co-

lecciones básicas, los problemas que

plantea la gran extensión de la

cuenca y, sobre todo, la carência de

trabajos orgânicos y de cierta con-

tinuidad, respaldados en métodos

adecuados de investigación.

Resulta un hecho bien conocido

aunque muchas veces olvidado en

los trabajos sistemáticos, que las

Nayades experimentan notables

variaciones bajo la acción modifi-

cadora dei biotopo en que se desar-

rollan, dando así lugar a formas de

reacción sumamente diversas, de

modo que no es de extranarse que

los distintos autores, ante ejempla-

res aislados de tales variaciones,

hayan podido distinguir otros tan-

tos tipos diferentes describiéndolos

como tales. Tal situación, que es de

validez general, ya fue senalada en

nuestro caso por Haas en varias

oportunidades y en especial en su

trabajo de 1930/31 (19). Reciente-

mente se ha dado a conocer un in-

teresante ensayo estadístico por

parte de Zilch (53) , respecto a las

especies paleárticas, donde se se-

hala que de 1309 especies descrip-

tas sólo resultan válidas 19 de ellas

y 58 subespecies. Esto revela in-

cuestionablemente la necesidad de

efectuar estúdios revisivos en pro-

fundidad, tendiendo a la reducción

cm

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10 11 12 13 14 15 16

64

Atas do Simpósio sobre a Biota Amazônica

de la frondosidad sistemática re-

sultante de una modalidad de tra-

bajo puramente descriptiva y de es-

caso fundamento científico.

A tal efecto venimos ensayando

desde un tiempo considerable la

aplicación de los caracteres deter-

minativos preconizados por Haas,

fundado en el estúdio de la escul-

tura umbonal y dei análisis de la

forma de la concha joven, combi-

nándolos con los propuestos por

Ortmann, basados en el estúdio dei

“glochidium”, la posición de la

marsupia en la branquía interna y

la forma y estructura de las bran-

quías. A todo ello debe sumarse, lo-

gicamente, el análisis conchológico

de amplias colecciones correspon-

dientes a una serie de localidades

representativas dentro de los gran-

des sistemas hidrográficos dei con-

tinente, tratando de correlacionar

tales variaciones con los caracteres

dei biotopo en que se desarrollan.

Debemos confesar que tal méto-

do sólo ha podido ser ensayado par-

cialmente en el caso de los Uniona-

cea dei Amazonas, ya que no he-

mos podido contar con la cantidad

de material suficiente, sobre todo

con las partes blandas conservadas,

ni con mayores informaciones acer-

ca de los caracteres de las aguas

en que fueron obtenidas, lo que ha

venido a limitar considerablemente

los alcances dei trabajo propuesto.

Pese a lo expuesto, se considera

de interés dar a conocer el presen-

te ensayo en la convicción de que

el mismo ha de ser de utilidad para

esclarecer, aunque sea en parte, la

complicada marana sistemática

creada en torno a estos moluscos,

y que es necesario proveer a una

información revisiva actualizada —

aun a riesgo de cometer errores —

que persistir en una situación como

la actual, tan confusa como esté-

ril, y carente de mayor significa-

ción científica.

LOS UNIONACEA AMAZÔNICOS

Los Unionacea de la cuenca ama-

zônica están compreendidos en la

familia Hyriidae, que contienen a

todos los representantes de Austra-

lasia y América neotrópica. Los úl-

timos integran la subfamilia Hyri-

inae, agrupándose en tres tribus:

Prisodontini, Castaliini y Diplodon-

tini (44). Las dos últimas son co-

munes a todas las grandes cuencas

dei continente sudamericano, en

tanto que la primera sólo se da en

el Amazonas y en algunas cuencas

más septentrionales, faltando com-

pletamente en los rios integrantes

dei sistema dei Plata.

La tribu Diplodontini comprende

sólo el género Diplodon Spix, cuyos

dos subgéneros Diplodon ss y Rhi-

pidodonta Mõrch, poseen especies

en la Amazônia. Castaliini posee

dos géneros: Castalia Lamarck y

Callonaia Simpson (10) , ambos con

representantes amazônicos, siendo

el último exclusivo de esta cuenca.

Volume 3 (Limnologia)

65

La tribu Prisodontini es descom-

puesta en los trabajos más actuali-

zados (42) en dos géneros: Paxyo-

don Schumacher y Prisodon Schu-

macher, siendo el último descom-

puesto en dos subgéneros : Prisodon

ss y Triplodon Spix. En realidad,

como se verá luego, se considera

que tal ordenamiento requiere con-

siderables ajustes y que, aun a tí-

tulo provisório, los últimos pueden

ser llevados a la categoria de gé-

neros.

El rasgo más característico de

los Unionacea de la cuenca amazô-

nica está dado por la presencia de

un género propio de la tribu Casta-

liini, el género Callonaia, y por

contener a los representantes de la

tribu Prisodontini, que si bien exis-

ten también en los rios de las Gua-

yanas, son características de este

sistema, faltan por completo en las

aguas de los grandes potamos que

concurren al Rio de la Plata.

Cabe destacar que aunque en la

cuenca amazônica se dan todos los

géneros que existen en la dei Pla-

ta, poseyendo además algunos ex-

clusivos y otros que faltan en la

última, el número de las especies

registradas no es mucho mayor, ya

que gran parte de los últimos, por

no decir su totalidad, son monotí-

picos. Es decir, que el número de

especies realmente válidas, en ge-

neral, aparece como muy limitado

contrastando tal situación con la

amplitud de la extensión geográ-

fica alcanzada por las mismas .

La enorme extensión de la cuen-

ca también se refleja en diferen-

cias distribucionales que, de mo-

mento, no parecen muy claras. De

mucho interés resultan en tal sen-

tido algunas áreas de engranaje,

especialmente las que definen los

afluentes que arrancan en puntos

próximos a las nacientes dei rio Pa-

raguay, donde parece producirse el

ingreso de algunas especies propias

dei sistema dei Plata, y viceversa,

fenómeno este que debe ser recien-

te o que no alcanzaría todavia una

gran extensión sobre ambas cuen-

cas.

Tribu: DIPLODONTINI

Género DIPLODON Spix

El género Diplodon Spix es el más

común y extendido entre todos los

Hyriinae, presentando una eviden-

te unidad de conjunto, distingui-

éndose claramente de los restantes

géneros de la subfamilia. La con-

formación regular de la concha, la

sencillez de la escultura umbonal

y dei aparato articular de las val-

vas, son bien característicos y no

exigen mayores comentários. Den-

tro de este conjunto se distinguen

dos subgéneros : Diplodon ss y Rhi-

pidodonta Mõrch, especialmente en

base a la forma “larval”, aunque

también puede sumarse a estos

ciertos detalles conchológicos y

anatómicos menos claros y defini-

3 — 37 121

cm

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66

Atas do Simpósio sôbre a Biota Amazônica

torios. El subgénero Diplodon ss,

posee “glochidium” parásito, en

tanto que Rhipidodonta se caracte-

riza por que las crias se desarrol-

lan directamente, completando en

la marsupia la formación de la al-

meja juvenil, es decir, sin requerir

una etapa de vida parásita.

Subgénero DIPLODON ss

Diplodon (Diplodon) granosus

granosus (Bruguière)

Unio granosa Bruguière, 1792

Haas al ocuparse de esta especie

en su importante trabajo de

1930/31 (19), distingue la existên-

cia de tres subespecies, haciendo

llegar a la típica desde las Guaya-

nas al estado de São Paulo, en tan-

to que distingue a D. granosus el-

lypticus (Spix) para el rio San

Francisco y los rios costeros de

Bahia, y a D. granosus multistria-

tus (Lea) para los rios de la pen-

diente atlântica dei sur de Brasil

hasta el estado de Santa Catarina

y el Alto Paraná.

Tales distingos no parecen muy

claros ni correctos pero, de cual-

quier forma, pueden ser aprovecha-

dos en parte, sehalando que lo

considerado como D. granosus el-

lypticus corresponde parcial o to-

talmente a simples formas de

D. rhombeus (Wagner) y reservan-

do el nombre de D. granosus mul-

tistriatus para el conjunto de for-

mas que se hacen presentes en los

rios de la pendiente atlântica de

Brasil, al sur dei rio San Francisco,

y en el Alto Paraná.

Cabe sehalar, además, que entre

los materiales estudiados por Haas,

así como por otros distintos auto-

res, no parecen encontrarse ejem-

plares de esta especie de procedên-

cia amazônica. Por mi parte sólo

posee unos pocos ejemplares, mal

conservados, que quizas puedan

corresponder a esta especie y cuya

única referencia es la “Rio Amazo-

nas”. El hecho llama poderosamen-

te la atención ya que si la especie

se extiende desde las Guayanas

hasta Santa Catarina y el Alto Pa-

raná, parecería definir un extenso

hiatus correspondiente a toda la

cuenca amazônica.

Claro está que es posible que esta

anomalia pueda atribuirse a las de-

ficiências de las colecciones existen-

tes, o a falta de una verdadera re-

lación específica entre D. granosus,

propiamente dicho, y el grupo de

especies que se subordinan cor-

rientemente a U. multistriatus Lea.

Caso contrario debemos admitir

que el Amazonas posee condiciones

que resultan inadecuadas al desar-

rollo de D. granosus, lo que indi-

caria que se trata de una es-

pecie particularmente estenotopa.

El problema merece un adecuado

estúdio y sólo puede ser resuelto

mediante la intensificación de las

investigaciones acerca de la espe-

cie típica, muy poco conocida, y la

Volume 3 (Limnologia)

67

realización de colecciones sistemá-

ticas en la cuenca que nos ocupa.

Diplodon (Diplodon) rhombeus

rhombeus (Wagner)

(Fig. 2)

Unio rhombeus Wagner, 1827

Unio rotundus Wagner, 1827

Unio patelloides Lea, 1860

Diplodon enno Ortmann, 1921

Diplodon jacksoni Marshall, 1928

Diplodon (Diplodon) beskeanus

nordestinus Haas, 1938

En diversas publicaciones ante-

riores se hizo referencia al hecho

de que D. rotundus Wagner y

D. fontaineanus Orb., pertenecían

a una misma especie, la que en su

distribución probablemente alcan-

zaría también al Amazonas. Reci-

entes estúdios llevados a cabo en el

museo de Senckenberg, Frankfurt,

sobre la colección de Ihering, han

venido a confirmar tal identidad

y a demostrar que la especie se ex-

tiende al Amazonas por el norte,

llegando por el sur hasta el Alto

Paraná y los rios costeros hasta el

estado de Santa Catarina, experi-

mentando a lo largo de tan exten-

so território grandes variaciones

conchológicas que dieran lugar a

una considerable cantidad de tipos

descriptos.

En conjunto, podemos distinguir

dos subespecies: Diplodon rhom-

beus rhombeus (Wagner) para el

Amazonas, el San Francisco y los

rios de la pendiente dei Atlântico

comprendidos entre ambas cuen-

cas; y a D. rhombeus fontaineanus

(Orb.) , que se extiende desde el rio

Doce y los rios costeros hasta el

estado de Santa Catarina y el Alto

Paraná.

La identidad de D. rhombeus con

D. rotundus no deja lugar a dudas,

confirmándose así lo expresado por

Haas en su fundamental trabajo de

1930/31. Lo mismo cabe expresar

respecto a D. patelloides (Lea).

Pero, a este conjunto de formas de-

cididamente redondeadas, que Haas

considerara equivocadamente como

propias dei subgénero Cyclomya

Simpson — Rhipidodonta Mõrch,

se hace necesario sumar otro, algo

más bajas, aunque local y circuns-

tancialmente pueden adquirir per-

fil redondeado. Entre ellas se en-

cuentra D. enno Ortmann, Diplo-

don beskeanus nordestinus Haas y

D. jacksoni Marshall. El rasgo co-

mún que las vincula está dado por

un conjunto de caracteres a los que

nos hemos referido anteriormen-

te (5) , y entre los que se destacan

una escultura de variable conver-

gência, a veces con varias costillas

confluentes, una ligera depresión

dei margen ventral por debajo de

los umbones, la forma moderada-

mente alargada de la concha ju-

venil con tendencia posterior al

crecimiento en altura, el escaso de-

sarrollo dei aparato articular de la

charnela, la tonalidad azulada-gri-

sácea dei nácar y ei color pardo

oscuro o negro mate dei periostra-

co. Por otra parte, la conformación

cm

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68

Afas do Simpósio sôbre a Biota Amazônica

dei “glochidium” parásito y la po-

sición de la marsupia en la bran-

quia interna (subcentral o ligera-

mente desplazada hacia adelante)

aportan otros tantos elementos

diagnósticos complementarios.

Cabe senalar la posibilidad de

que D. ellypticus (Spix) correspon-

da también a este conjunto de for-

mas, cuando que en general se lo

considerara vinculado a D. grano-

sus. En este caso, los otros nom-

bres deberían subordinársele por

razones de prioridad.

Diplodon (Diplodon) parodizi

Bonetto

Diplodon parodizi Bonetto, 1960

Unio burroughianus Lea, parcial-

mente en Orbigny, 1834

Unio burroughianus Lea, en So-

werby, 1886

Diplodon eharruanus (Orb.), par-

cialmente en Haas, 1930

Diplodon eharruanus (Orb.), en Bo-

netto, 1953

Esta especie, tan común en aguas

dei Paraná medio e inferior y dei

rio Paraguay, se hace presente

también en los afluentes dei Ama-

zonas que nacen en Bolivia, de

acuerdo a lo expressado — aunque

no muy claramente — por Orbig-

ny (41), lo que se deduce dei ejem-

plar que reproduce y comenta So-

werby (49) * y a lo que hemos

podido establecer a través de al-

gunas muestras procedentes dei rio

San Miguel, afluente dei Guaporé.

En el resto de la cuenca amazô-

nica parece ser desconocida, lo que

* La referencia de estos autores

corresponde a D. burroughianus (Lea)

vendría a indicar que se trata de

una especie de reciente incorpora-

ción a la misma a través de las ca-

beceras dei rio Paraguay.

La especie es fácilmente recono-

cida por su forma moderadamente

alargada rematada posteriormen-

te en un ângulo marcado, por el

relieve de la escultura con clara

convergência de las costillas cen-

trales, y la posesión de un “glochi-

dium” parásito.

Diplodon (Diplodon) parallelopi-

pedon (Lea)

(Fig. 1)

Unio parallelopipedon Lea, 1834

Unio acutirostris Lea, 1866

? Diplodon trifidus (Lea) , en Ort-

mann, 1921

En el ano 1921 Ortmann (43)

describe, sin proporcionar figura,

a lo que considera el verdadero

U. trifidus Lea, expresando su con-

vicción de que esta especie es ama-

zônica y que la localidad origina-

ria (Buenos Aires), senalada por

Lea, correspondería a un error ya

que, hasta entonces, no había vuel-

to a ser encontrada.

En el ano 1953, al ocupamos de

la fauna de Nayades dei rio Para-

ná (3), sehalábamos que esta es-

pecie existe, aunque parece ser al-

go rara, en el Paraná medio.

Por otra parte, el lote origi-

nal de Ortmann constituido por

6 ejemplares obtenidos por Hase-

man en el rio Guaporé, cerca de

Volume 3 (Limnologia)

ò <x

1. — Diplodon (Diplodon) parallelopipedon (Lea), materiales dei Guaporé

atribuídos por Ortmann a D. trifidus (Lea) ; fig. 2 — paratipos de Diplodon enno

rtmann = Diplodon (Diplodon) rhombeus rhombeus Wagner (2a: ejemplar de

orcm; 2b; ejemplar de 31mm) ; fig. 3 — algunas variaciones extremas de Diplodon

«nipidodonta) suavidicus (Lea) (3a: paratipo de Diplodon garbei lhering, Lagoa

Juparanã , Espírito Santo, Brasil, ejemplar de 29mm; 3b: paratipo de Unio

hartwrighti lhering, Rio Amazonas, ejemplar de 16mm).

São Simão, Mato Grosso, Brasil,

presenta muchos rasgos particula-

res que los llevan a diferir consi-

derablemente de U. trifidus Lea, es-

pecialmente por lo que hace al per-

fil de la concha joven, al particular

cm l

SciELO

70

Atas do Simpósio sôbre a Biota Amazônica

desarrollo de la escultura y a su

marcada inclinación hacia atrás.

Estudiando las formas jóvenes dei

lote de Ortmann, se advierte que

el perfil se ajusta estrechamente

al de D. parallelopipedon, y que si

bien la escultura posee una mayor

acentuación, número de costillas,

y parece más inclinada, sus rasgos

esenciales son prácticamente los

mismos. El color dei periostraco,

bastante más claro, tampoco cons-

tituiría un rasgo excluyente, ya

que los ejemplares de Ortmann pa-

recen provenir de aguas lóticas, en

tanto que la totalidad de nuestros

materiales dei rio Paraná y aun dei

Uruguay, proceden de aguas lénti-

cas. Consideramos que esta misma

circunstancia puede explicar las di-

ferencias en la escultura y el per-

fil de los ejemplares adultos, dife-

rencias estas que, en caso de ser

constantes en los materiales ama-

zônicos, podría justificar el distin-

go de una subespecie.

De cualquier manera, la presen-

cia de D. parallelopipedon en estas

aguas ya fue senalada por d’Orbig-

ny, quien indico su halazgo en el

rio San Miguel de Bolívia, que es

tributário dei Guaporé. Lamenta-

blemente no nos ha sido posible es-

tudiar los materiales de este autor

para establecer mejor la relación

de los mismos con los ejemplares

de Ortmann que comentáramos an-

teriormente.

Subgénero RHIPIDODONTA

Mõrch

Diplodon (Rhipidodonta)

suavidicus Lea

(Fig. 3)

Unio suavidicus Lea, 1856

Diplodon hartwrighti Ihering, 1910

Diplodon garbei Ihering, 1910

Diplodon kelseyi F. Baker, 1913

Diplodon obsolescens F. Baker, 1913

Esta es una especie característi-

ca dei Amazonas, aunque parece

extenderse hacia territórios más

septentrionales — quizas alcanzan-

do el Orinoco — y también hacia

el sur, por lo menos hasta el rio

Doce, en el Estado de Espírito

Santo.

La escultura, la conformación de

la concha joven, la presencia de

un “glochidium” de desarrollo di-

recto y la moderada pero evidente

gravitación de la marsupia hacia

la parte posterior, proporcionan

generalmente suficientes elemen-

tos diagnósticos para su fácil iden-

tificación, permitiendo de tal ma-

nera aclarar considerablemente los

problemas sistemáticos planteados

en torno a esta especie y al conjun-

to de tipos que realmente se le de-

ben subordinar.

Diplodon hartwrighti Ihering

corresponde evidentemente a esta

especie, por lo menos en lo relati-

vo a los materiales de Ihering pro-

cedentes dei Amazonas, los que

Volume 3 (Limnologia)

71

representan sólo una forma de

D. suavidicus, algo alargada, angu-

losa, expandida posteriormente y

de charnela muy reducida. Diplo-

don obsolescens F. Baker, corres-

pondería a una simple acentua-

ción de los caracteres de tal varia-

ción.

Diplodon garbei Ihering, que

fuera considerada por Haas como

sinónima de D. beskeanus Dunker

— D. rhombeus Wagner, debe in-

cuestionablemente ser subordinada

a la especie que nos ocupa, como

lo evidencia el análisis conchológi-

co y lo confirma el estúdio dei

“glochidium” (7) .

Diplodon kelseyi F. Baker, cor-

responde a una forma de D. suavi-

dicus (Lea) , que ha alcanzado un

considerable desarrollo con engro-

samiento de las valvas, modifican-

do ligeramente los detalles dei con-

torno. Pero la concha juvenil se

4 — Diplodon (Rhipidodonta) hylaeus hylaeus (Orbigny), rio Alto Paraguay

(ejemplar de 39mm) ; fig. 5 — Diplodon (Rhipidodonta) hylaeus pazi (Hidalgo),

laguna aãyacente al rio Napo, Ecuador, ejemplar de 31mm que reproduce muy

bien la forma de Castalia pazi Hidalgo; fig. 6 — paratipo de Diplodon hasemani

Ortmann = Diplodon (Rhipidodonta) hylaeus pazi (Hidalgo)

( ejemplar de 15mm) .

cm l

SciELO

72

Atas do Simpósio sôbre a Biota Amazônica

ajusta perfectamente a la de la es-

pecie de Lea.

Por lo que respecta a los tipos

extraamazónicos septentrionales,

que presumiblemente deben subor-

dinarse o fueran subordinados a

D. suavidicus, nos abstenemos de

considerarlos aqui ya que poseen

una conformación un tanto parti-

cular cuyo estúdio exige mayor

cantidad de materiales dei que dis-

ponemos o dei que hemos podido

estudiar hasta el presente.

Diplodon (Rhipidodonta)

hylaeus pazi Hidalgo

(Figs. 4-6)

Unio hylaea Orbigny, 1835

Castalia pazi Hidalgo, 1868

Diplodon hasemani Ortmann, 1921

Diplodon (Diplodon) guaranianus

hasemani Haas, 1931

Ecuadorea bibliana Marshall &

Bowles, 1951

Diplodon hylaeus Orbigny cons-

tituye una especie de amplia distri-

bución en el centro dei continen-

te sudamericano, presentando una

fisionomia inconfundible por el

amplio desarrollo de la escultura,

su relevância y gravitación hacia

la parte posterior. Aunque no todo

parece estar resuelto en torno al

conocimiento de esta especie y a

los tipos que supuestamente se le

atribuyen, creemos que pueden dis-

tinguirse dos subespecies: Diplodon

hylaeus hylaeus, para los rios dei

sistema hidrográfico platense, y

D. hylaeus pazi para las aguas de

la cuenca amazônica.

La subespecie última, que es la

que nos ocupa, viene a caracteri-

zarse por ser en general más redon-

deada y más regularmente escultu-

rada que la típica. En realidad, el

tipo de U. hylaeus Orb., correspon-

diente al Alto Paraguay, se aleja

considerablemente de la subespecie

amazônica, pero estas diferencias

son menos acentuadas en el caso

de las formas dei Paraguay inferior

y Paraná medio, como U. guara-

nianus Orb. y D. asunsionis Mar-

shall.

Por lo que hace a los sinónimos

consignados, no creo que hagan

falta mayores comentários ni de-

mostraciones para justificar su

subordinación. Quizas, no obstan-

te, resulte necesario extenderse un

poco respecto a la inclusión de

Ecuadorea bibliana Marshall & Bo-

wles, forma fósil de la localidad de

Biblián, Ecuador, cercana a algu-

nos afluentes dei Amazonas. Los

depósitos en que la especie fuera

encontrada son de edad incierta a

estar de los autores, quienes le

acreditan una considerable anti-

güedad en base a que ésta y otras

especies de gasterópodos que la

acompahan no tendrían represen-

tantes actuales. En verdad, no hay

nada que separe a Ecuadorea bi-

bliana de Diplodon hylaeus pazi,

siendo los rasgos de la escultura,

de marcado tipo convergente, en-

Volume 3 (Limnologia)

73

teramente similares. Coincidentes

son también el área nodulosa de-

finida hacia la parte posterior y el

perfil redondeado de la concha.

Cabe sehalar, por último, que

esta subespecie parece ser relativa-

mente común en los afluentes dei

Amazonas próximos a las nacientes

dei Paraguay, en el Maranón, en

el Solimões y el Negro, no existien-

do referencias a su presencia en

otros puntos de la cuenca.

Tribu : PRISODONTINI

La tribu Prisodontini compren-

de a un conjunto de especies ca-

racterizadas por la posesión de pro-

cesos aliformes a los extremos de

la línea dorsal, y el considerable

desarrollo dei aparato articular de

la charnela, con variable tendencia

a la formación de dentículos o es-

trias verticales. El “glochidium” es

de tipo parásito, de conformación

subtriangular, con dientes dividi-

dos distalmente en espínulas agu-

das.

En un reciente trabajo de Ols-

son & Wurtz (42) se establecieron

bases importantes para la ordena-

ción sistemática dei grupo, partien-

do de la forma y extensión de los

dientes de la charnela respecto a

la cicatriz dei adductor anterior, y

la presencia o ausência de la escul-

tura. Resumiendo lo expresado por

tales autores tendríamos:

A) Charnela confuertes dientes la-

melares anteriores que sobre-

pasan a la cicatriz dei adductor

(Tipo: Paxyoãon ponderosus

Schumacher, 1817)

B) Charnela con diente cardinal

anterior generalmente no bien

definido, a menudo en forma de

dentículos, los que alcanzarían

pero no sobrepasan a la cica-

triz dei adductor anterior.

Género Prisodon Schumacher

(Tipo: Prisodon obliquus

Schumacher, 1817)

Este último comprende a los si-

guientes subgéneros:

Bl) Con superficie de la concha

lisa — Prisodon ss

B2) Con superficie de la concha

esculturada — Triplodon

Spix

(Tipo: Triplodon rugosum

Spix, 1827)

Esta ordenación parece bastante

simple y lógica, si bien se estima

necesario introducirle algunas en-

miendas. Es así que Prisodon obli-

quus Schumacher posee también

dientes anteriores que sobrepasan

la cicatriz muscular anterior, exis-

tiendo 2 en la valva derecha y ge-

74

Atas do Simpósio sôbre a Biota Amazônica

neralmente 1 en la izquierda que

cumplen tal condición. Esto puede

apreciarse claramente en las con-

chas de ejemplares jóvenes y me-

diano desarrollo, tendiendo a redu-

cirse en los de mayor tarnaho, para

ajustarse entonces a la figura de

Schumacher. Tal circunstancia y

la falta de escultura parece indi-

car que existen relaciones mucho

más estrechas entre Paxyodon y

Prisodon, que entre este último gé-

nero y Triplodon Spix. Además, se

considera que este último, por ca-

recer de dientes que sobrepasen la

cicatriz dei adductor anterior y por

la relevância de la escultura, debe

ser elevado a la categoria de géne-

ro. En consecuencia, el esquema de

Olsson & Wurtz puede ser acep-

tado provisoriamente con el sigui-

ente reajuste:

A) Charnela con fuertes dientes

anteriores que sobrepasan a la

cicatriz dei adductor anterior.

Laterales estriados vertical-

mente a veces algo divididos.

Concha sin escultura.

Género Paxyodon Schumacher

(Tipo: Paxyodon ponderosas

Schumacher, 1817)

B) Charnela con delgados dientes

lamelares anteriores que sobre-

pasan la cicatriz dei adductor

anterior, los que se reducen

sustancialmente con el creci-

miento. Laterales lisos sin es-

triación vertical. Concha sin

escultura.

Género Prisodon Schumacher

(Tipo: Prisodon obliquus

Schumacher, 1817)

C) Charnela fuerte en que los dien-

tes anteriores alcanzan pero no

sobrepasan la cicatriz dei ad-

ductor anterior. Concha fuer-

temente esculturada.

Género Triplodon Spix

(Tipo: Triplodon rugosum Spix,

1827 = Hyria corrugata Lamarck,

1819)

Los tres géneros así distingui-

dos serían monotípicos.

Género PAXYODON Schumacher

Paxyodon syrmatophorus

(Meuschen)

(Fig. 7)

Mya syrmatophora Meuschen in

Gronovius, 1781

Paxyodon ponderosus Schumacher,

1817

Hyria avicularis var. “b” Lamarck,

1819

Unio brownianus Lea, 1838

Hyria complanata Hupé, 1857

Hyria alata Sowerby, 1869

La especie, además de los carac-

teres de la charnela aludidos, se

caracteriza por carecer de escultu-

ra, por la existência de pliegues

transversos posteriores en las cer-

canias dei umbón, por poseer pro-

Volume 3 (Limnologia)

cesos aliformes bien desarrollados

y presentar una arista posterior

muy marcada. El periostraco es

castano lustroso y el nácar rosáceo

dándose localmente un intenso co-

75

lor asalmonado. El “glochidium”

recuerda en su conformación y ta-

mano al de Castaliini, pero los

dientes difieren sustancialmente

ya que rematan en dos o tres espí-

tiv' Ei em pla. r joven de Paxyodon syrmatophorus Meuschen dei rio Tocan-

fipo ílg ‘ ® — ejemplar joven de Prisodon obliquus Schumacher, dei rio Iriri;

fare — ejemplar joven de Triplodon corrugatus Lamarck, procedente de San-

vnrf™’’ n0 ■ Amazona s; fig. 10 — extremo anterior de la valva izquierda de Pri-

*oaon obliquus Schumacher (10a) y de Triplodon corrugatus Lamarck (10b).

mostrando la posición de los dientes respecto a la cicatriz dei adductor anterior.

cm l

SciELO

76

Atas do Simpósio sobre a Biota Amazônica

nulas muy agudas aunque algo

más rectas que en caso de Diplo-

dontini (4). La marsupia se en-

cuentra claramente desplazada ha-

cia adelante, ocupando los dos ter-

cios anteriores de la branquía.

La especie resulta bastante co-

mún en los tramos inferiores dei

Amazonas y en sus afluentes, exis-

tiendo también en las Guayanas.

Género PRISODON Schumacher

Prisodon obliquus Schumacher

(Fig. 8)

Prisodon obliquus Schumacher,

1817

Hyria avicularis Lamarck, 1819

Unio caudatus Wagner, 1827

Diplodon furcatum Spix, 1827

Hyria elongata Swainson, 1841

Unio macropterus Dunker, 1846

Hyria castelnaudi Hupé, 1857

Unio ortonii Lea, 1868

Hyria recta Sowerby, 1869

A los caracteres diferenciales

mencionados anteriormente (for-

ma y extensión de los dientes an-

teriores y la carência de escultura)

que deben considerarse como fun-

damentales, puede sumarse el mar-

cado alargamiento de la concha, su

conformación subtriangular y el

color blanco dei nácar. Fuera de

lo senalado, poco es lo que se pue-

de indicar como rasgo de importân-

cia dado la considerable variabili-

dad de la especie, como queda tra-

suntado a través de la lista de si-

nónimos que se acompana.

Tal lista no requiere mayor jus-

tificación. Sowerby ya estableció

en 1869 la subordinación de Unio

caudatus Wagner, Diplodon furca-

tum Spix e Hyria elongata Swain-

son respecto a H. avicularis La-

marck, concepto que es compartido

por Simpson. H .castelnaudi Hupé

e H. recta Sowerby son considera-

das por Simpson como probables

sinónimos de P. obliquus. Unio ma-

cropterus Dunker, como senala

Haas (19), se identifica perfecta-

mente con la especie que nos

ocupa.

En cambio, Unio ortonii Lea

plantea mayores dificultades ya

que se trata de un tipo basado en

un ejemplar grande, desgastado y

de crecimiento algo anómalo, en el

que los dientes anteriores han con-

servado en gran parte los rasgos

de la concha joven. Se considera,

no obstante, que la ubicación acor-

dada es la correcta.

La especie parece ser exclusiva

dei Amazonas y sus tributários.

Género TRIPLODON Spix

Triplodon corrugatum (Lamarck)

(Fig. 9)

Hyria corrugata Lamarck, 1819

Triplodon rugosum Spix, 1827

Mya angulata Wood, 1828

Hyria transversa Hupé, 1857

Hyria exasperata Sowerby, 1869

Hyria latialata Sowerby, 1869

Hyria rugosissima Sowerby, 1869

Unio stevensii Lea, 1871

Hyria jamauchinensis F. Baker,

1913

Hyria amazônica Frierson, 1914

Prisodon ( Triplodon) rugosissima

savillei Olsson & Wurtz, 1951

Volume 3 (Limnologia)

77

Los caracteres de la charnela y

la escultura hacen que la especie

resulte inconfundible, pese que a

través dei vasto território que

cubre en su distribución experi-

mente considerables modificacio-

nes, sea en el perfil, el diâmetro o

en el desarrollo y convergência de

la escultura. Pero tales modifica-

ciones, aunque de aparente rele-

vância, son de escasa significación,

ya que las mismas se relacionan a

través de muchas formas de pasa-

je, lo que indica la inoperancia y

falta de validez de los distingos es-

pecíficos efectuados.

Tal hecho explica, por sí mismo,

la lista de sinónimos consignada

que, por otra parte, resume y am-

plia la opinión general de la mayor

parte de los autores.

El “glochidium” de la especie es

de tipo parásito y resulta muy ca-

racterístico (11). Su contorno res-

ponde al de Diplodcn Spix, a igual

que la forma dei diente aplicado

a cada valva embrionária. Pero este

diente presenta a cada lado una

expansión lamelar que se va ensan-

chando desde el extremo dei mismo

hasta la base de implantación, para

perderse en el reborde dei “glochi-

dium”. Lo expuesto parecería indi-

car que el género Triplodon — Hy-

ria Lamarck, presenta mayor afi-

nidad con el género Diplodon que

con respecto a Paxyodon (el “glo-

chidium” de Prisodon resulta aún

desconocido) , lo que plantea un

problema pleno de interesantes su-

gerencias.

Esta especie resulta frecuente en

la cuenca dei Amazonas y sus tri-

butários, así como también en los

rios de las Guayanas.

Tribu : CASTALIINI

La tribu Castaliini integra un

conjunto de especies que poseen

caracteres bien definidos entre los

que cabe citar la conformación

triangular o subcuadrangular de

la concha con una variable trunca-

dura posterior, la carência de pro-

cesos aliformes, la arista posterior

muy marcada, los umbones promi-

nentes y recurvados, y la charnela

de fuerte desarrollo. El “glochi-

dium”, de tipo parásito, es sub-

triangular equilátero o isósceles,

con un corto y agudo diente en for-

ma de espina, careciendo de fila-

mento larval.

Género CASTALIA Lamarck

Castalia Lamarck, 1819

Tetraplodon Spix, 1827

Castalina Ihering, 1891

Castaliella Simpson, 1900

Chevronais Olsson & Wurtz, 1951

El género Castalia Lamarck, de

acuerdo a las conclusiones de un

ensayo que diéramos a conocer re-

cientemente (10), eonstituye un

conjunto homogéneo cuyos rasgos

más característicos están dados por

el grosor de la concha, su perfil

78

Atas do Simpósio sobre a Biota Amazônica

subtriangular o subcuadrangular,

por los umbones prominentes y va-

riablemente esculturados, la arista

posterior bien acusada, una mode-

rada truncadura posterior, y el

fuerte desarrollo de las piezas ar-

ticulares de la charnela. El “glochi-

dium” es de tipo parásito, de forma

subtriangular equilateral, con fuer-

tes dientes triangulares.

Dentro de la cuenca amazônica

se hacen presente dos especies:

Castalia ambigua ambigua La-

marck y Castalia sulcata orbignyi

(Hupé & Deville) .

Castalia ambigua ambigua

Lamarck

Castalia ambigua Lamarck, 1819

Castalia cuaãrilatera Orbigny, 1835

Castalia acuticosta Hupé, 1857

Castalia túrgida Hupé, 1857

Castalia retusa Hupé, 1857

Castalia crosseana Hidalgo, 1865

Castalia hanleyana Sowerby, 1869

Castalia latiquadrata Sowerby, 1869

Tetraplodon baro Ihering, 1910

Tetraplodon juruanus Ihering, 1910

Chevronais colombiana Olsson &

Wurtz, 1951

Recientemente (10) nos hemos

ocupado de esta especie con cierta

amplitud, no considerándose nece-

sario insistir sobre el particular. La

misma se extiende a toda la cuenca

amazônica, y la lista de sinónimos

que se acompaha ilustra suficien-

temente acerca de las modificacio-

nes operadas en las valvas a través

de tan extenso território.

Castalia sulcata orbignyi (Hupé

& Deville)

Castalia sulcata Krauss, 1849

TJnio orbignyi Hupé & Deville, 1850

Esta especie alcanza un conside-

rable tamaho, diferenciándose de

la forma típica de las Guayanas

por la falta de surcos concêntricos,

la desaparición total de la escultu-

ra, la carência de indícios de es-

trias verticales en la charnela y el

color blanco dei nácar.

Género CALLONAIA Simpson

Callonaia Simpson, 1900

El género Callonaia se caracte-

riza fundamentalmente por su for-

ma triangular, por la arista poste-

rior muy alta, aguda y saliente,

que se extiende hasta la base de la

concha; por la definida truncadura

posterior, el ligamento muy corto

y la carência de escultura. A esto

se asocian otros caracteres menos

significativos como la relativa del-

gadez de las paredes de la concha,

el considerable diâmetro de la mis-

ma y el color castaho claro dei

periostraco, etc. El “glochidium”,

aunque muy semejante al de Cas-

talia, es de mayor tamaho, con evi-

dente predomínio de la longitud so-

bre la altura, poseyendo dientes

triangulares más gráciles, con bor-

des incurvados hacia adentro.

Volume 3 (Limnologia)

79

El género comprende una so-

la especie, propia dei Amazonas:

C. ãuprei (Recluz).

Callonaia Duprei (Recluz)

Castalia duprei Recluz, 1843

Castalia dolabella Sowerby, 1869

Esta hermosa especie se desarrol-

la, al parecer, en los tramos infe-

riores dei Amazonas y en los tri-

butários correspondientes, pudien-

do alcanzar un gran tamano.

CONCLUSIONES

A través dei análisis realizado y

de los antecedentes expuestos pue-

de expresarse que la fauna de Unio-

nacea dei Amazonas viene a carac-

terizarse fundamentalmente por la

presencia de algunos géneros pro-

Pios, o restringidos a estas aguas

y a la de las Guayanas, los que pre-

sentan una conformación que se

aparta considerablemente de la pri-

mitiva que caracteriza al género

Diplodon Spix, representando así,

desde el punto de vista concholó-

gico, las formas más especializadas

dentro de los Unionacea neotrópi-

cos.

Estos géneros ( Paxyodon , Priso-

don, Triplodon y Callonaia) son

monotípicos, y aun cuando no re-

sultaren correctas las presentes

conclusiones sistemáticas, siempre

aparecerían con un número muy

limitado de especies.

En la cuenca amazônica se n-

cuentran también todos los restan-

tes géneros de Unionacea que se

dan los distintos sistemas hidro-

gráficos dei continente, incluyendo

en esto el género Diplodon Spix,

con una representación equivalen-

te a la que existe en los grandes

rios dei sistema dei Plata.

Todo esto induce a pensar que

la cuenca dei Amazonas constituye

actualmente el centro de evolución

de mayor importância para la sub-

familia Hyriinae Swainson, que en-

globa a todos los Unionacea neo-

trópicos.

Otro aspecto de interés estaria

dado por cierta pobreza o limita-

ción en la distribución y numerosi-

dad de las especies dei género Di-

plodon Spix, cuyo carácter marca-

damente estenoico ya fuera sena-

lado por nosotros en diversos tra-

bajos. Evidentemente, la considera-

ción objetiva dei tema exige mu-

chos más elementos de juicio dei

que disponemos actualmente. Em-

pero, el contraste que presenta con

el notable desarrollo, abundancia

y amplia distribución de las espe-

cies de Prisodontini, es un hecho

concreto que indica la necesidad

de una adecuada investigación.

Por último, merece senalarse que

en las áreas correspondientes a las

nacientes dei rio Paraguay y dei

Guaporé, parece produeirse una

zona de engranaje entre las espe-

cies propias dei Amazonas y las de

cm

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10 11 12 13 14 15 16

80

Atas do Simpósio sobre a Biota Amazônica

los rios dei sistema dei Plata (fe-

nómeno que se da también para

con diversas especies de Mutela-

cea) , la que se extiende variable-

mente sobre ambas cuencas. Diplo-

don parallelopipedcn Lea, D. paro-

dizi Bonetto, entre los Unionacea,

y Anodontites ensiformis Spix, en-

tre otros Mutelacea, constituyen

ejemplos dei fenómeno senalado,

pareciendo evidente la reciente in-

corporación de las primeras a las

aguas amazônicas, y de la última

al rio Paraguay y Paraná medio.

RESUMO

Efetua-se uma revisão dos Uni-

nacea da bacia amazônica, anali-

sando o valor dos diferentes gêne-

ros, espécies, subespécies, descritas

para a mesma. De tal análise resul-

ta que, ainda que na bacia amazô-

nica existam gêneros próprios,

aparte dos que são comuns a ou-

tros sistemas hidrográficos de Sul-

América, o número de espécies não

é muito maior do que o registrado

nos grandes rios do sistema do Pra-

ta. Assinala-se a relativa escassez

e moderado tamanho das espécies

de Diplodon, o que contrasta com o

grande desenvolvimento, abundân-

cia, e ampla distribuição alcança-

da pelas espécies de Prisodontini,

estimando-se que o Amazonas cons-

titui atualmente o centro de evo-

lução de maior importância para

os Unionacea neotropicais.

SUMMARY

A revision of the Unionacea of

the Amazonian Basin is made, ana-

lyzing the value of the different

genera, species and subspecies de-

scribed for it. That analysis shows

that although there are some ge-

nera characteristic of the Amazo-

nian Basin, apart from those that

are common to other South Ame-

rican river systems, the number of

species is not superior to that re-

gistered in the great rivers belong-

ing to the River Plate System. The

relative shortage and moderate size

of the species of the Diplodon ge-

nus are noticeable, in contrast

with the great development, abun-

dance and distribution of the Pri-

sodontini species. The Amazon is

considered as the most important

centre of evolution of the neotro-

pical Unionacea at present.

BIBLIOGRAFIA

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kenbergiana, 12:

19. Haas, F„ 1930-31, Versuch einer

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kanischen Najaden. Senckenber-

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20. Haas, F., 1932, Beitráge zur Kenn-

tnis der Verbreitung südamerika-

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21. Haas, F., 1938, Neue Binnen-Mol-

lusken aus Norost-Brasilien. Arch.

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Binnen-Mollusken NO-Brasilien.

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24 . Haas, F., 1949, On Fresh-water Mol-

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25. Haas, F., 1950, Some land and

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26. Hidalgo, J. Gonzáles, 1865, Diag-

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29. Ihering, H„ 1893, Najaden von S.

Paulo und die geographische Ver-

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breitung der Süsswasser-Faunen

von Südaxnerika. Arch. Naturg .:

45-140.

30. Ihering, H., 1910, Uber brasilianis-

che Najaden. Abh. Senck. Nat. Ges.

32.

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Conch. Cab. Martini & Chemnitz, 9

( 2 ).

33. Lamarck, J. B., 1815-1822, Histoire

Naturelle des Animaux sans Ver-

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de Catalogo dos molluscos do Bra-

sil. Arq. Mus. Paranaense, 7:

35. Lea, l, 1834-1874, Observations on

the genus Unio, Philadelphia.

36. Marshall, W. B., 1926, New land

and fresh-water mollusks from

Central and South America. Proc.

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37. Marshall, w. B., 1928, New fresh-

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1932, New fóssil fresh-water mol-

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Najaden der Gattungen Castalia,

Schleschiella und Ecuadorea. Arch.

Moll., 79:

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Voyage dans 1’Amérique Méridio-

nale, 5, Part. 3.

42. Olsson, A. A. & Wurtz, C. B., 1951,

New Colombian Naiades; with ob-

servations on other species. Notu-

lae Natur ae, 239:

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can Najades: a contribution to the

knowledge of the freshwater mus-

sels of South America, Mem. Car-

negie Mus., Pittsburgh, 8; 33.

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Taxonomy and Zoogeographic re-

lationships of the South American

Naiades. Malacologia, 1 (2) :

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deux Coquilles nouvelles, Mag. Zool.

46. Schtjmacher, F. C„ 1817, Essai d’un

nouveau systeme des habitations

des vers Testacea.

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Najades or pearly fresh-water

mussels, Proc. U.S. Nat. Mus., 22

(1205):

48. Simpson, C. T., 1914, A descriptive

Catalogue of the Najades or pearly

freshwater mussels, Michigan, Ann

Arbour Press.

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graph of the genus Unio, Hyria &

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50. Spix, J. B. & Wagner, J. a., 1827

Testacea Fluviatilia quae in itinere

per Brasiliam .... Leipzig.

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logy 1821-1822, 2 ed„ Hanley.

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(4):

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 83-88 — 1967

NOVOS DADOS PARA O CONHECIMENTO DE

“PHREATOBIUS CISTERNARUM” GOELDI (Pisces,

Pygidiidae, Phreatobiinae)

ANTENOR LEITÃO DE CARVALHO

Museu Nacional, Rio de Janeiro, Guanabara

(Com uma figura no texto)

Em 25 de março de 1963 recebi

do meu amigo R. P. Arlé, natura-

lista do Museu Nacional a serviço

no Museu Emílio Goeldi, Belém do

Pará, uns croquis a lápis e a aqua-

rela de um minúsculo bagre,

de côr vermelha intensa, encon-

trado quando cavavam um poço

para água potável em terreno de

uma rua de Belém. Os croquis es-

tavam acompanhados das notas,

que abaixo transcrevemos:

“Aqui segue o croquis de um pei-

xinho achado na escavação de um

poço profundo na Angostura. Não

tem pigmento melânico e pelo que

pude vêr com o bicho vivo, não me

Parece ter nenhum sinal de olhos.

É todo vermelho (pink vivo) . Creio

que é uma espécie de lençol sub-

terrâneo — larva? adulto? Veja o

que pode deduzir pelo croquis e me

escreva depressa”.

Em baixo dos croquis havia o se-

guinte :

“Belém — Achado ao cavar um pôço

na Angostura, com 10-15 metros de pro-

fundidade. Todo o corpo vermelho vivo

(muito mais vivo que no desenho) as

nadadeiras e barbas brancas. De baixo

da binocular (animal vivo) não achei

olhos, sòmente um leve tracinho de

pigmento transversalmente por cima

da bôca. O animal encontra-se vivo

(por enquanto) em aquário meu”.

Comuniquei-lhe que pelo que

pude apreender dos croquis e no-

tas, tratava-se de Phreatobius cis-

ternarum Goeldi, 1904, Pygidiidae

muito raro, só conhecido pelos

exemplares de Goeldi. Pedi-lhe que

procurasse mantê-lo vivo e obser-

vasse o seu comportamento em

aquário.

Tempos mais tarde, em 1965, re-

cebi do colega Arlé, as seguintes

notas:

“O Phreatobius cisternarum está fi-

xado após um ano em aquário, resolvi

matá-lo para não perdê-lo.”

cm

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10 11 12 13 14 15 16

84

Atas do Simpósio sôibre a Biota Amazônica

“O especimem foi encontrado ao

cavar um poço na travessa Angostura

em Belém.”

‘‘Foi-me trazido numa garrafa (com

farinha) como alimento!! foi transfe-

rido para um aquário de 12 litros, al-

tura da água 17 centímetros, fundo de

areia com detritos finos, água velha e

absolutamente límpida, com algumas

plantinhas e algas. O aquário foi colo-

cado em lugar sombrio. À noite cos-

tumava acender em cima uma lâm-

pada fraca para poder observá-lo.”

“O peixe era inteiramente vermelho

com a parte ventral anterior e as bar-

batanas esbranquiçadas. Conservou a

mesma côr viva durante todo o tempo,

nadava em plena água com movi-

mentos ondulatórios às vêzes descan-

sando sôbre pequenas plantas. Percor-

ria sempre com as barbas armadas o

fundo do aquário mas não ficava es-

condido sob folhas ou detritos, parava

sempre nos cantos laterais do aquário

em posição vertical sempre com a ca-

beça para cima. Nunca aceitou peque-

nas tubifex mesmo cortadas, nem da-

fnias, parecia se alimentar somente

com coisas extremamente pequenas

como algas. Viveu assim em perfeita

saúde durante um ano exatamente e

teria vivido mais se não o matasse, fi-

xando-o no formol com receio de per-

dê-lo. Conservou a côr vermelha ainda

alguns dias no formol. Ao fixá-lo o

tubo digestivo aparecia contendo algas

de côr verde.”

Decorreram 62 anos desde que

Goeldi anunciou o seu achado, sem

que aparecesse na literatura espe-

cializada notícia de novos exempla-

res.

Êste ano por interferência do

Dr. José Cândido de Melo Carva-

lho, obtive mais 2 exemplares pro-

venientes de Macapá, Território

Federal do Amapá. Foram coligidos

em dezembro de 1965, pelo meu ve-

lho amigo Reinaldo H. G. Damas-

ceno, quando aprofundavam um

poço, durante a estiagem.

A ocorrência da espécie em três

pontos distantes, no delta do Ama-

zonas (de Macapá a Belém em li-

nha reta são 320 km) faz-nos supor

que a espécie é mais abundante do

que parece e que a região do delta

está cortada por canais subterrâ-

neos, que das barrancas do rio en-

tram para o interior e a costa da

ilha, a uma profundidade de 10 a

20 metros, e provàvelmente anas-

tomosando-se.

E’ provável também que nos mi-

lhares de poços espalhados pela re-

gião existam muitos habitados pela

espécie, sem que seus proprietários

tomem conhecimento da ocorrên-

cia. O sucesso dos três achados de-

ve-se à curiosidade e ao interêsse

pelas Ciências naturais, dos seus

coletores.

Infelizmente não pudemos obter

a descrição original de Goeldi, ti-

vemos que nos apoiar na monogra-

fia de Eigenmann (1918), que ba-

Volume 3 (Limnologia)

85

seou as diagnoses do gênero (mo-

notípico) e espécie na fotografia e

no exemplar que lhe fôra cedido

por Fuhrmann.

Quanto à côr, Eigenmann não

esclarece nada; diz somente “côr

uniforme”. É provável que nem

Goeldi os tenha visto vivos e nem

fôsse informado pelo coletor sôbre

a côr, em vida, dos exemplares.

P i s c e s

Pygidiidae

Phretobiinae Myers, 1944

Phreatobius Goeldi, 1904

Tipo por monotipia Phreatobius

cisternarum Goeldi, 1904

Phreatobius Goeldi, C. R. 6 Congres.

intern. Zool. Berne 1904 (1905) :

545; Fuhrmann, Verh. Schweiz.

Naturf. Gesel. Aarau, 1905 (1906):

50; Arch. Sei. Phys. Nat. Genève,

1905 (1906), 4 (20): 578; Eigen-

mann, Rep. Princeton Exped. Pata-

gônia 1896-1899, 1910 3 (4): 387;

Mem. Carnegie Mus. 1918, 7 (5) :

371, Gosline, Boi. Mus. Nac. (n. s.)

Zool. 33: 68; Myers, Calif. Acad.

Sei. 4 ser. 1944, 23 (40) : 597:

Fowler, Arq. Zool. S. Paulo, 1954,

9: 9.

Phrenatobius Jordan, Stanford Univ.

Publ. ser. 43 (Genera of Fishes) 4:

480, 1920, citacão e referência er-

radas; Stanford Univ. Publ. Univ.

Ser. 3 (2) : 151, 1923 (Classification

of Fish) citação e referências er-

radas.

Goeldi (1904) achava que Phrea-

tobius deveria ficar entre os Cetop-

sidae e Trichomycteridae. Fuhr-

mann achava-o aliado a Clariiâae

da fauna africana. Eigenmann

(1910) colocou-o na família Siluri-

dae, subfamília Pimelodinae decla-

rando que não estava seguro quan-

to à posição do gênero. Em 1918,

em sua revisão da família Pygidi-

idae, colocou-o no apêndice daque-

la monografia. Gosline, em 1945,

colocou-o entre os Pygidiidae, não

sabendo porém em que subfamília

deveria inclui-lo. Myers (1944), co-

locou-o em Pygidiidae criando a

subfamília Phreatobiinae. Fowler

(1954) colocou-o em Trichomycte-

ridae, Phreatobiinae.

P. cisternarum Goeldi, 1904

Localidade típica — Ilha de Ma-

rajó.

P. cisternarum Goeldi, C. R. 6 Congr.

intern. Zool. Berne, 1904 (1905) :

545; Fuhrmann, Verh. Scheweiz

Naturf. Gesell. Aarau 1905 (1906):

50-51; Arch. Sei. Phys. Nat. Genève

(4) 20: 578-579, 1905 (1906); Ei-

genmann, Rep. Princeton Exped.

Patagônia 1896-1899, 1910, 3 (4) :

387-388; Mem. Carnegie Mus. 7 (5) :

86

Atas do Simpósio sôbre a Biota Amazônica

371-373, Fig. 39 pl. 56 fig. 1, 2, 4,;

Gosline, Boi. Mus. Nac. (n. s.)

Zool. 33: 68; Myers, Proc. Calif.

Acad. Sei. 1944, Ser. 4, 23 (40):

594; Fowler, Arq. Zool., S. Paulo

1954, 9: 9-10, fig. 596.

Recentemente, um nôvo peixe

cego de águas subterrâneas (Famí-

lia Characidae), foi descrito por

Brittan, M. R. & Bohlke, J. E., No-

tulae Naturae, n.° 380, outubro de

1965, publicação da Academia de

Ciências Naturais de Filadélfia.

Desta feita, o peixinho, com

23,6 mm de comprimento, foi obti-

do de uma perfuração de 30 m de

profundidade, na localidade minei-

ra de Jaíba.

Fig. 1 — Mapa do delta do Amazonas, mostrando as localidades onde foram

coligidos exemplares de Phreatobius cisternarum Goeldi.

Volume 3 (Limnologia)

87

RESUMO

O aparecimento de Phreatobius

cisternarum em mais duas locali-

dades do delta do Amazonas, decor-

ridos 62 anos da data de sua des-

crição, em localidades afastadas

mais de 300 km entre si, trouxe-

mos novos subsídios para o conhe-

cimento da espécie.

Dentre êsses subsídios poderemos

enumerar os seguintes:

Um exemplar viveu durante um

ano (após o qual foi sacrificado)

em um pequeno aquário, instalado

em lugar sombrio.

Refugava as tubifex e dafnias

que lhe eram oferecidas.

Alimentou-se provàvelmente com

partículas orgânicas microscópicas

e algas verdes.

Percorria o fundo do aquário

com os barbilhões armados, como

a inspecioná-lo.

Descansava em posição vertical

num dos cantos do aquário, sempre

com a cabeça para cima, próximo

a superfície.

E’ de côr vermelha muito inten-

sa, com as nadadeiras, barbilhões

e parte infero-anterior do corpo es-

branquiçados.

Atingem até 60 mm de compri-

mento.

Vivem em galerias de águas sub-

terrâneas, na região do delta do

Amazonas, a uma profundidade

aproximada de 10 a 20 metros e

aparecem nos poços cavados para

água potável, quando as galerias

são rompidas ao escavarem-se os

mesmos.

SUMMARY

The appearance of Phreatobius

cisternarum in two more localities

in the Amazon delta, 62 years after

its description and in site 300 km

apart, has added new data to our

knowledge of the species.

A specimen lived for one year

in small, shaded aquarium after

which it was killed. It refused the

tubifex and daphnia that were of-

fered, and probably ate only green

alga and microscopic organic par-

ticles.

It swam about the floor of the

aquarium with its barbeis spread,

as though examining the surface.

It rest in a vertical position in a

corner of the aquarium, always

with the head uppermost and near

the surface. Its color is a intense

red with the fins barbeis and an-

terior ventral surface whitish. The

fish reaches 60 mm in length.

They live in the waters of un-

derground galleries in the Amazon

delta, at depths of 10 to 20 meters,

and may appear in wells when

these intersect one of the galleries.

cm

SciELO

10 11 12 13 14 15 16

88

Atas do Simpósio sôbre a Biota Amazônica

REFERÊNCIAS BIBLIOGRÁFICAS

Eigenmann, C. H„ 1910, Catalogue of

fresh-water fishes of tropical and

south temperate America. Rep.

Princeton Exped. Patagônia 1896-

-1899, 3 (4) : 375-511.

Eigenmann, C. H„ 1918, The Pygidiidae,

a family of South American cat-

fishes. Mem. Carnegie Mus., 7 (5) :

259-398, pis. 36-56, text.-figs. 1-39.

Fuhrmann, O., 1905 (1906) , Scleropages

forviosum und über Phreatobius

cisternarum. Verti. Schweiz. Naturf.

Ges. Aarau,: 50-51.

Fuhrmann, O., 1905 (1906), Arch. Sei.

Phys. Nat. Genève, (4) 20: 578-579.

Fowler, h. W„ 1954, Os peixes de água

doce do Brasil. Arq. Zool. S. Paulo,

9: IX + 400 pp.

Goeldi, E. A., 1904 (1905), Nova zoolo-

gica aus der Amazonas, Region

Neue Wirbeltiere. C. R. 6 Congres.

Intern. Zool., Berne,-. 542-549.

Gosline, W. A., Catalogo dos Nematog-

natos de Agua Doce da America do

Sul e Central. Boi. Mus. Nac.

(n.s.), Zool., 33: 1-138.

Jordan, D. S., 1920, The Genera of

Fishes 4: 41-576. Stanford Univer-

sity Publications, University Series

n.° 43.

Jordan, D. S., 1923, A Classification of

Fishes, Including Families and

Genera as Far as Known. Stanford

Univ. Publ., Univ. Ser., Biol. Sei.,

3 (2) : 77-243 + I-X.

Myers, G. S., 1944, Two extraordinary

new blind Nematognath fishes

from the Rio Negro, representing a

new subfamily of Pygidiidae, with

a rearrangement of the genera of

the family, and illustrations of

some previously described genera

and species from Venezuela and

Brazil. Proc. Calif. Acad. Sei. 4 Ser,

23 (40) : 591-602, 1 text fig., pis. 52-

56.

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 89-92 — 1967

BASES PARA EL ESTÚDIO DE LAS RAYAS DE AGUA

DULCE DEL SISTEMA AMAZONICO. NUEVAS

SINONIMIAS DE “P. MOTORO” (M.H., 1841)

M ARIANO N. CASTEX S.J.

Centro de Investigación Biológica, San Miguel, Argentina

(Con 1 figura en el texto )

En nuestro trabajo comunicado

al Congreso Latino Americano de

Zoologia realizado en Santiago de

Chile en octubre de 1965 — amplia-

ción de nuestra comunicación con

motivo dei cincuentenario dei Mu-

seo Provincial de Ciências Natura-

les “Florentino Ameghino” de la

ciudad de Santa Fe, en mayo de

1964 — establecimos una revisión

de lo realizado hasta la fecha como

aporte al conocimiento de la fami-

lia de rayas de agua dulce (Pota-

motrygonidae Garman, 1913).

En el Octavo Congreso Interna-

cional de Medicina Interna en no-

viembre de 1964 (Buenos Aires) y

en el Primer Simposio de Toxinas

Animales realizado en Atlantic

City (EE.UU.) en abril de 1966 pre-

sentamos todos los datos conoci-

dos acerca dei aspecto de la toxi-

cidad de este elasmobranquio dul-

ceacuícolo.

Como indicáramos en el trabajo

de Chile, los conocimientos que se

tienen sobre las rayas de agua dul-

ce en la cuenca amazônica son muy

pobres y hasta confusos, cosa muy

diversa por cierto en lo que a la

cuenca dei Paraná se refiere, en

donde gracias al apoyo dei Institu-

to Nacional de Limnologia se ha

podido iniciar un estúdio intenso

que está aclarando bastante el pa-

norama.

Para no extendernos demasiado

y tomando por base nuestro traba-

jo presentado a Chile, considerare-

mos las especies descriptas para la

cuenca amazônica, las que incluí-

das en lo que llamamos Región

Amazônica — Platense agrupába-

mos entonces en la subregión ama-

zônica. Así poníamos las siguientes

especies contenidas en dos géneros:

Disceus thayeri Garman, 1877; Po-

tamotrygon motoro (M. H., 1841) ;

P. hystrix (M. H., 1841); P. trra-

chyurus (Günther, 1880); P. lati-

ceps Garman, 1913; P. circularis

Garman, 1913; P. Dumerilii (Cas-

telnau, 1855); P. humerosus Gar-

90

Atas do Simpósio sóbre a Biota Amazônica

man, 1913; P. signatus Garman,

1913; P. strongylopterus (Schom-

burgk, 1843) ; P. scobina Garman,

1913.

En nuestro reciente viaje a los

Estados Unidos en donde visitamos

el Smithsonian Institute, el Ame-

rican Museum of Natural History

y el Museum of Comparative Zoo-

iogy de Harvard, tuvimos oportu-

nidad de entrar en contacto con la

colección Garman, la que hemos

revisado cuidadosamente para ex-

poner en la presente comunicación

nuestras conclusiones, ya que mo-

difican bastante el cuadro ante-

riormente expuesto.

De la revisión de los ejemplares

de la colección Garman y de la ins-

pección de otro ejemplar gigantes-

co obtenido dei Rio Guaporé y que

se halla actualmente en el Ameri-

can Museum (N. York) , queda bien

claro que Disceus thayeri es género

válido con especie bien distingui-

ble y exclusiva dei interior de la

hoya amazônica, hallándosela en

toda su extensión.

Con respecto a P. signatus, he-

mos revisado los ejemplares catalo-

gados en Harvard. No habiendo

Garman designado tipo, luego de

cotejar cuidadosamente los ejem-

plares con la descripción dei autor

citado, se ha creído oportuno asig-

nar el tipo al numero 304, ejem-

plar macho. Con respecto a los

otros tres ejemplares puede indi-

carse lo siguiente: El N.° 604 es un

ejemplar de P. motoro, siendo aún

apreciables las manchas amarillen-

tas dei dorso y estando en muy

buen estado de conservación sus

dentículos dorsales. El N.° 600 es

un ejemplar asimilable a P. moto-

ro. Finalmente el N.° 560 es un

ejemplar de P. reticulatus (Gün-

óher, 1880) .

En lo que respecta a P. circularis

rotulado bajo el N.° 295 y el P. sco-

bina N.° 602, no hemos hallado di-

ferencias apreciables entre ambas

y las asimilamos a P. motoro.

El N.° 299 rotulado como P. hu-

nierosus, ejemplar hembra provisto

de numerosas y gruesas espinas es

tambien asimilable a P. motoro

siendo su única característica

curiosa el grossor de las espinas

que recubren por entero la cola.

Finalmente los ejemplares rotu-

lados como P. laticeps divergen en

sus aspectos. El N.° 294 es P. mo-

toro. El N.° 298 es también asimi-

lable a P. motoro. En cuanto al

tipo rotulado bajo el número 608

es demasiado joven para ser iden-

tificado asimilándose por su mor-

fologia en forma indistinta a P. mo-

toro o a P. hystrix. El N.° 287 es

también indudablemente una P.

motoro.

En un trabajo especial nos pro-

ponemos describir cuidadosamen-

te cada ejemplar y fundamentar

nuestras aserciones, labor que es-

capa los fines de la presente co-

municación.

Volume 3 (Limnologia)

Pig. 1 — Disceus thayeri; at. dei Museo de Zoologia Comparada de Harvard.

No queremos concluir sin indicar

que el error de Garman al crear

cuatro especies ahora asimilables

con P. motoro echa raiz en la fal-

ta de material, ya que para cuatro

especies contó con once ejemplares.

nuestra parte hemos podido

observar en más de cinco mil ejem-

plares de P. motoro observados du-

rante vários anos en la cuenca dei

Nio Paraná la variabilidad morfo-

lógica de la especie P. motoro.

Merecen párrafo especial dos es-

pecies que consideramos dudosas:

P. strongylopterus y P . dumerilii.

La primera es perfectamente asi-

milable con P. signatus, siendo en

ese caso esta última especie sinó-

nima de la primera. En cuanto a

P. dumerilii cae en las mismas con-

sideraciones que la especie ante-

rior.

Considerados estos antecedentes

podemos establecer como base de

especies existentes en la hoya ama-

cm l

SciELO

92

Atas do Simpósio sôbre a Biota Amazônica

zónica das siguientes : Disceus tha-

yeri; Potamotrygon motoro; P. hys-

trix; P. brachyurus; P. reticulatus;

e P. signatus.

Todas estas especies son comu-

nes con las halladas ya en cuencas

nor-amazónicas o ya en cuencas dei

sur, a no ser D. thayeri que es —

como dij éramos — exclusiva dei

Amazonas.

Omitimos las descripciones y las

bibliografias pertinentes por con-

siderar que el interesado puede hal-

larlos en nuestros trabajos ante-

riores en donde nos hemos referido

a ellos en forma exhaustiva.

Queremos senalar como dato de

interés que al norte dei Amazonas

quedan dos especies no hallables en

su cuenca. Son ellas P. magdale-

nae propia dei sistema colombiano

y P. schroederi Fernández Yepez,

1958 perteneciente al sistema dei

Orinoco y que no ha sido aún men-

cionada para el Amazonas o sus

afluentes.

Con respecto al Sistema Paraná-

platense hay descriptas algunas es-

pecies cuya presencia en el sistema

amazônico tampoco ha sido sena-

lada. Son ellas P. labradori Castex,

1963, P. pauckei Castex, 1963,

P. falkneri Castex, 1963, P. schuh-

macheri Castex, 1964 y la muy

curiosa especie P. menchacai Mar-

tínez Achenbac., 1966.

Finalmente cabría preguntarse

qué posible conexión pudiera tener

la especie africana de agua dulce

descripta para el afluente dei Rio

Niger (P. garouaensis Stauch —

Blanc, 1962) con las especies ama-

zônicas.

BIBLIOGRAFIA

Castex, M. N., 1963, La raya fluvial,

Santa Fe.

Castex, M. N., 1963, El género Potamo-

trygon en el Paraná medio. Rev.

Mus. Prov. Ci. Nat. Santa Fe, 2 (1) :

1 - 86 .

Castex, M. N„ 1963, Observaciones sobre

el P. motoro. Com. Mus. Arg. Ci

Nat. B. Rivaáavia, 1 (2) Hidrobio-

logía.

Castex, M. N., 1963, Una nueva especie

de raya fluvial: P. labradori. Neo-

tropica, La Plata, 9 (30) : 117-121.

Castex, M. N., 1963, Una nueva especie

de raya fluvial: P. pauckei. Boi.

Acad. Nac. C. Córdoba, 43: 289-294,

Castex, M. N., 1963, La enfermedad Pa-

ratrygónica. Rev. Asoc. Méd. Arg.,

78 (6) : 314-324; Prensa Méd. Arg.,

51: 217-222 y 1085-1095; Rev. Ass.

Méd. Arg., 79 (11) : 547-556.

Castex, M. N., 1964, Una nueva especie

de raya fluvial americana: P.

schuhmacheri. Neotrôpica, La Pla-

ta, 10: 92-94.

Castex, M. N., 1965, Notas sobre la fa-

milia Potamotrygonidae Garman

1913. Publ. Téc. N. 13. Dir. Rec. Nat.

Prov. Santa Fe.

Castex, M. N., 1964, Bases para la revi-

sión de la familia Potamotrygoni-

dae Garman 1913. Publ. Cincuente-

nario. Mus. Prov. C. Nat. Santa Fe.

Castex, M. N., 1965, Observaciones sobre

un lote de P. magdalenae. Physis,

25 (70): 239-243.

Castex, M. N., 1965, Notas sobre algunos

ejemplares curiosos de la familia

Potamotrygonidae Garman 1913.

Physis, 25 (70) : 245-247.

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 93-96 — 1967

nemertinos de água doce da região amazônica

DIVA DINIZ CORRÊA

Faculdade de Filosofia, Ciências e Letras,

Universidade de São Paulo, São Paulo

No rico material de vermes ama-

zônicos, coletado pelo Dr. Haraid

Sioli, foram verificados quatro es-

pécimes de nemertinos do gênero

Prostoma Dugès, 1828, coletados

no rio Tapajós, em Fordlândia e na

desembocadura do rio Cupari, aflu-

ente direito do Tapajós.

Três das quatro Ordens de ne-

mer tinos são hoje conhecidas para

as águas doces da América do Sul

e Central: o heteronemertino Sio-

Hneus turbidus du Bois-Reymond

Marcus, 1948, do rio Tapajós, duas

espécies de hoplonemertinos do gê-

nero Prostoma, P . rubrum (Leidy,

1850) e P. eilhardi (Montgomery,

1895) e o bdelonemertino Malacob-

della auriculae Blanchard, 1847, do

Chile.

Prostoma rubrum, da América do

Norte, foi verificado no México

(Rioja, 1941) e na Venezuela (Cor-

DE Ro, 1943). A distribuição geográ-

fica de P. eilhardi ainda não pode

ser definitivamente estabelecida

devido a dificuldades taxonômicas.

De acordo com a sinonímia de

Stiasny Wijnhoff (1938) Berlin,

Amsterdam e a Lombardia seriam

localidades de P. eilhardi. Os acha-

dos sul-americanos referiam-se aos

Estados brasileiros de São Paulo e

Paraná (Marcus, 1942, 1943) . Pos-

sivelmente também o material do

Uruguai e Argentina pertencem a

esta espécie (Cordero, 1943).

Os principais caracteres do ma-

terial amazônico são: comprimen-

to cêrca de 2,5 a 4,5 mm; largura

cêrca de 0,3 mm; côr creme; em

geral 6 olhos com irregularidade

no número e distribuição; cílios ou

cerdas táteis ausentes; glândulas

cefálicas situadas anteriormente ao

cérebro; corpúsculos calcáreos na

epiderme e perênquima ausentes;

esôfago com epitélio rincodeal, sem

cílios; estômago ciliado, rincocela

longo; rincódeo sem músculos lon-

gitudinais; órgãos sensoriais, fron-

tal e cerebrais, presentes.

Na sua sinopse do gênero Prosto-

ma, Stiasny-Wijnhoff (1938) re-

cm

SciELO

10 11 12 13 14 15 16

94

Atas do Simpósio sôbre a Biota Amazônica

corda 16 nomes diferentes aplica-

dos aos nemertinos de água doce e

dá a bibliografia correspondente.

Apenas 6 espécies foram reconheci-

das como válidas. Afora algumas

divergências de opinião considero

a lista dêsse autor como correta.

Comparei o material amazônico

com cada uma delas tendo porém

acrescentado a espécie P. rubrum,

que não foi considerada apesar de

ter sido revalidada por Coe (1918),

considerando-a idêntica a P. grae-

cense.

P. lumbricoideum tem 30 mm de

comprimento, é pintada de escuro

e possui apenas 4 olhos. P. rubrum

não possui órgão frontal e os dutos

das glândulas cefálicas não são

unidos como no material amazô-

nico. P. grande tem 35 mm de com-

primento, possui manchas verdes,

rincocela curto e glândulas cefáli-

cas mais curtas que nos vermes

amazônicos. P. padanum tem rin-

cocela muito curto e estilete cen-

tral muito mais longo que o do ma-

terial amazônico. P. puteale é bran-

co, sem olhos.

Esta rápida revisão mostra que

os vermes amazônicos não perten-

cem a nenhuma destas 5 espécies.

Restam para comparação mais por-

menorizada as espécies P. graecen-

se e P. eilhardi que foram separa-

das por Stiasny-Wijnhoff com ba-

se nos seguintes caracteres:

1 — sem ou com cílios táteis;

2 — sem ou com corpúsculos cal-

cáreos;

3 — poros cerebrais laterais ou

ventrais;

4 — órgão frontal tripartido ou

simples;

5 — glândulas cefálicas précere-

brais ou póscerebrais;

6 — rincódeo sem ou com mús-

culos longitudinais;

7 — base do estilete sem ou com

constrição;

8 — músculos longitudinais do

estômago originados da mus-

culatura cefálica ou do

septo;

9 — esôfago rincodeal ou ciliado;

10 — sem ceco ou com ceco curto;

11 — divertículos intestinais ul-

trapassando o cérebro ou

apenas atingindo o cérebro;

12 — vaso dorsal projetado no rin-

cocela com um nó ou vaso

dorsal normal.

A aplicação de 8 dêstes caracte-

res não tem sido satisfatória, nem

são êles suportados pelas descri-

ções originais, não podendo assim

ser mantidos. Restam apenas 4 dos

critérios mencionados dos quais

apenas 2 suportam críticas e são

usados comumente.

1 — Cílios táteis ocorrem em grae-

cense e mesmo cerdas táteis

na região anal e são ausentes

em eilhardi. De acordo com a

Volume 3 (Limnologia)

95

minha experiência é muito

difícil ou impossível detectar

cílios ou cerdas táteis em ma-

terial conservado. Assim não

convém determinar todo ma-

terial fixado, sem cílios táteis,

como P. eilhardi.

2 — Corpúsculos calcáreos são

presentes em graecense e au-

sentes em eilhardi. Êles são

provàvelmente restos tempo-

rários armazenados que au-

mentam em vermes mantidos

em condições desfavoráveis.

Se as condições melhorarem

êles são, pelo menos parcial-

mente, reabsorvidos ou elimi-

nados. Um caráter fisiológi-

co pode certamente servir

taxonômicamente tão bem

quanto um morfológico, mas

seu valor sistemático diminui

muito se êle variar de acordo

com as condições do ambi-

ente.

3 — P. eilhardi não possui como

P. graecense uma espêssa ca-

mada de músculos longitudi-

nais na parede do rincódeo.

Êste caráter mencionado por

Stiasny-Wijnhoff pode ser

aceito sem restrições.

* • — O epitélio do esôfago em ei-

lhardi é do tipo do epitélio do

rincódeo enquanto que o epi-

télio do esôfago de graecense

é ciliado. Êste caráter, esôfa-

go rincodeal ou não rincodeal,

é considerado também um

bom caráter disjuntivo entre

as duas espécies.

Como os vermes da região ama-

zônica possuem rincódeo sem ca-

mada de músculos longitudinais e

esôfago rincodeal, sem cílios, devem

ser classificados como Prostoma ei-

lhardi (Montgomery, 1895). Acres-

cento que corpúsculos calcáreos são

ausentes.

Tendo tido oportunidade de clas-

sificar material a mim enviado, da

África do Sul, notei que os vermes

podiam, à primeira vista, ser sepa-

rados em dois lotes. Os cortes vie-

ram confirmar a separação e no

material africano encontrei não

apenas a espécie amazônica, acima

mencionada, mas também P. grae-

cense (Bõhmig, 1892). Êstes pos-

suem rincódeo com camada espês-

sa de músculos longitudinais e esô-

fago ciliado, não de tipo rincodeal .

Esta espécie possui corpúsculos

calcáreos no parênquima o que foi

utilisado como sinal suplementar

(Corrêa, 1951).

BIBLIOGRAFIA

Coe, W. R., 1918, The Nemerteans. Cap.

XIV (p. 454-458) de Ward &

Whipple, Fresh-water Biology.

New York.

Cordero, E. H., 1943, Hallazgos en di-

versos paises de Sud America de

nemertinos de agua dulce dei ge-

cm

SciELO

10 11 12 13 14 15 16

96

Atas do Simpósio sôbre a Biota Amazônica

nero Prostoma. An. Acad. Bras.

Cien., 15 (2) : 125-135.

Corrêa, D. D., 1951, Freshwater Nemer-

tines from the Amazon Region and

from South África. Boi. Fac. Fil. Ci.

Letr. XJniv. S. Paulo, Zoologia, 16:

257-270, pis. 1-2.

Marctjs, E„ 1942, Sôbre um Nemertino

de água doce do Brasil. An. Acad.

Bras. Cien., 14 (4) : 371-383.

Marctjs E„ 1943, Novos achados de Ne-

mertinos límnicos. An. Acad. Bras.

Cien., 15 (1) : 11-17.

Marctjs, E. dtj Bois-Reymond, 1948, An

Amazonian Heteronemertine. Boi.

Fac. Fil. Ci. Letr. TJniv. S. Paulo,

Zoologia, 13: 93-109, pis. 1-3.

Rioja, E., 1941, Hallazgo en Xochimilco

de Stichostemma rubrum (Leidy)

Nemerte de agua dulce. An. inst.

Biol., México, 12 (2) ; 663-668.

Stiasny-Wijnhoff, G., 1938, Das Genus

Prostoma Dugès, eine Gattung von

Süsswasser Nemertinen. Arch.

Néerland. Zool., Suppl., 3: 219-230.

cm

SciELO

10 11 12 13 14 15 16

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 97-108 — 1967

ON THE ECOLOGY OF AMAZONIAN

RAIN-FOREST STREAMS

ERNST-JOSEF FITTKAU

Hydrobiologische Anstalt der Max-Planck-Gesellschaft, Plõn, Germany and

Instituto Nacional de Pesquisas da Amazônia, Manaus, Brasil

(With one text-figure)

The enormous quantities of wa-

ter which the Amazone is contin-

ually carrying to the Ocean have

their offspring somewhen and

somewhere in hundreds of thou-

sands of springs and streams of its

vast tributary area. Before these

waters assemble in the main river

and change into the homogenous

clay - coloured whitewater (“água

branca”) or Amazone water, they

run transparent, occasionally

browned by humic acid, for the

most part in the shade of Virgin

forests, and there they represent a

particular biotope, the rain-forest

stream, which hitherto has hardly

been taken notice of. When adding

together the surfaces of the innu-

íherable small streams, the result

tvould be many times the multiple

of the surface of the Amazone Ri-

ver. And when adding the lengths

of these streams, the result would

7 ~ 37 121

be a watercourse more than a

thousand times longer than the

Amazone. From these considera-

tions may be concluded the very

important part these streams act

in the formation of the Amazonian

rain-forest region.

The Amazonian rain - forest

stream is fundamentally different

in several ecological factors from

the streams of other regions and

climates. Its water is extraordi-

narily poor in soluble minerais, di-

rect solar radiation does general-

ly not reach the water surface. The

water temperature is extremely

constant. Plant life is almost com-

pletely missing, the fauna is poor

and rather simple. The entire bio-

coenosis of that extreme biotope

depends as for its fundamental ali-

mentation upon allochthonous or-

ganic matter conveyed into the

stream. The main ecological factor

cm l

SciELO

LO 11 12 13 14 15 16

98

Atas do Simpósio sôbre a Biota Amazônica

by which the development of or-

ganisms is limited is the scarcity

of soluble minerais. This factor, to-

gether with the lack of solar ra-

diation, is the reason for the scar-

ceness of plant life and cause, ei-

ther directly or through the result-

ing uniform sort of food, the ab-

sence of many groups of animais

otherwise generally found in

streams. The remarkable stability

of water temperature, which out-

side the tropics in inland waters is

only found in springs, is consider-

ed to be of minor importance .

The typical form of the rain-fo-

rest stream is found on the “terra

firme” in the central Amazonian

region, which has been formed by

the sediments of the miocene-plio-

cene fresh-water lake (compare

Sioli . . . ) . In the border regions of

the Amazonian basin, where the

geological formations are different

the water chemism is very often

not so extreme, so that a partially

different composition of the bio-

coenosis of the streams may result.

On the following pages we will

give a description of the rain-forest

stream such as it is found in “Cen-

tral Amazônia”. In this context we

understand by such a stream a

small watercourse that takes its

origin from springs. It changes to

become a river at a spot where the

forest does no longer completely

shelter its bed. This occurs, accord-

ing to the type of forest, at a

width from about 5 to 10 m. In its

upper part the stream mostly runs

in a narrow valley, deeply cut in

soft tertiary sediments; which af-

ter joining with other streams most

often quickly gets wider and gener-

ally soon becomes the wide sur-

face of a river.

From physiographic and ecologi-

cal points of view three different

zones of a stream may be distin-

guished (Fig. 1) : (1) the spring -

or erosion-zone, or upper course,

(2) the sedimentation-zone, or

middle course, (3) the so called

Igapó-zone, or lower course. In

most of the cases the stream takes

its offspring from helocrenes,

which in the rain-forest climate

more or less continually give water

throughout the year. Rheo - or lim-

nocrenes are extremely rare.

In the upper course, i.e. in the

spring- or erosion-zone, the stream

carrying little water only runs at

the bottom of its valley without re-

markably meandering. Its drop is

relatively strong, but erosion is

weak, the small quantities of wa-

ter being continually dammed by

fallen trees and leaves, and regions

of running and stagnating water

often alternating. Many times the

stream in its beginnings gets lost

in helocrene-like swamps charac-

terised by quantities of the Buriti

palm, Mauritia flexuosa.

The augmentation of its water

volume gives the stream a clean,

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Volume 3 (Limnologia)

99

sandy bed which is limited by

banks fastened by roots. When the

valley is becoming wider and thé

drop is diminishing, the stream

starts meandering and changing

into its middle course, the sedi-

mentation-zone . After strong

downpours the water occasionally

flows over the bounds temporarily.

The bank is often a little higher

than the bottom of the valley. The

latter is more or less on the same

levei as the médium surface of the

water of the main river system.

Annually during the high water

period the stream can therefore be

dammed in the region of its mid-

dle course and its valley can be

more or less flooded. Whilst the

water stagnates at the bottom of

the valley, it generally goes on run-

ning in the proper bed. The mid-

dle course is characterised by a

sandy bed, mostly devoid of wood,

and its strong meanders with a

frequent change between flat and

deep water. Particularly during the

high water period the diminished

current causes, at respective spots

where both sand and leaves form

sedimentations, vast deposits of

sand and leaves to be formed.

Very slowly, but also rather

abruptly after a Cascade formed by

soft tertiary arenites, the middle

course changes into the lower cour-

se . the so called Igapó-zone. The

hed of the stream is below the mé-

dium high water mark of the main

river system, and according to its

low levei is annually flooded by the

waters of the main river, which

fills the wide valley of the stream .

In the region of Manaus the water

levei on an average goes up resp.

down for about 13 m. Only during

the low water period this part of

the river, from an ecological-phy-

siographic point of view represents

a stream, whilst during the high

water period it represents a section

of the main river, the warm water

of which covers the cooler water

of the stream and its bottom and

there to a large extent stagnates.

In the Amazonian region the Iga-

pó or flood-wood makes part of the

ecologically most extreme biotope,

which moreover within the area of

the lower part of a stream in the

course of the year is subject to a

continuai change due to rising or

falling water and cannot be com-

pared with any other limnic bio-

tope. The following pages will not

deal in particular with this dyna-

mical region of waters.

The water of springs resp.

streams is, as is indicated in the

table, extremely poor in soluble

minerais. (Tab. 1) The rain that

enters into sour impoverished soils

placed on tertiary fresh-water se-

diments, can in its phase as sur-

face water hardly absorb electro-

lyts. Of all elements, except sili-

cium, natrium, and potassium,

there are only traces available. It

100

Atas do Simpósio sôbre a Biota Amazônica

has been impossible by means of

hitherto usual methods to trace

calcium. The water is, as well as

the soils there, very acid, with a

pH of about 4.5. The proportion of

free C0 2 is about 20 — 30 mg/l. The

proportion of oxygen does mostly

not reach saturation. On certain

edaphic conditions, if there are

podsol-soils in the tributary area

(compare Klinge), the surface

water gets more or less rich of so-

luble humic acid, by which it be-

comes brown to redbrown. The

typical biocoenosis of the stream

is, however, not influenced by the

proportion of humic acid. In the

springs the water temperature is

on an average 24.5° C. In the

stream itself it varies very little.

The daily and annual oscillations

are about ± I o C. As has been

initially mentioned, the stream is

usually shielded against direct

solar radiation. About 1/lOOth to

l/200th of the mid-day radiation

reach its surface.

The stream floor is filled with

sand; gravei and stones are mis-

sing in this region. Occasionally

the water runs over horizontal

layers of tertiary arenites, whose

ruptures bring about cascades,

which, when situated in the middle

or lower course, annually remain

submerged for a rather long time.

The banks are shallow and abrupt

and are fastened by thick pads of

thin roots. These paddings of fine

roots on the banks represent the

most important solid substratum

for the rheophile fauna; in addi-

tion to these the pieces of fallen

trees and fixed leaves and, in sec-

tions of weak current, also thick

layers of old leaves. In the middle

course, but even more in the lower

course the roots of epiphytes (Ara-

ceae) hanging down from trees in

the water and forming intense ra-

mifications there, constitute a re-

markable substratum. Even at a

varying water levei they are always

swimming on the surface and also

during an almost complete stagna-

tion during the high-water period

they form a suitable substratum

for the rheophile fauna. There are

to be found in these root-clusters

considerable numbers of different

species and their individuais.

Aquatic plants are represented,

if at all, only by a few forms. Pads

formed by Chlorophyceae or Cya-

nophyceae are completely missing.

Lower plants are often represented

by clusters of Batrachospermaceae

(Rhodophyceae) . These algae are

obviously refused by animais as

food and also as substratum. On

the surface levei are occasionally

found several sorts of Musci and

also Hepaticae, and a small fern

which tolerates even some months

of inundation. The only flowering

plant often to be found in the

streams is the semi-aquatic Thur-

nia sphaerocephala (Thumiaceae) .

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Fig. 1 — Schematic aspect of the different ecological regions of the Central-

Amazonian rain-jorest stream.

It grows up to the length of a me-

ter or more in deep shade, on mud-

dy banks as well as on the sandy

floor in the midst of the current.

Only on spots with strong solar ra-

diation it is found submerged and

floating in the current. In lenitic

sections is occasionally to be found

a very small Utriculariaceae. Near

cascades the forest is occasionally

low owing to the stony surface and

does not completely shield off the

sunlight. On this sort of spots the

likewise semi-aquatic Tonia fluvia-

tilis (Ericaulaceae) is found root-

ing in the fissures of rocks, which

otherwise are missing in the

stream. On spots where the forest

near the streams has been burnt

down, so that the sunlight directly

reaches the water surface and so-

luble minerais are conveyed into

the stream by rain, grow small

quantities of Cyanophyceae and

Chlorophyceae, and on the banks

Cyperaceae and various kinds of

Ericaulaceae.

The composition of the stream

fauna is determined as well by the

chemism of the water as by the

food in offer, the non-existence of

the usual autochthonous organic

primary production. The complete

absence of Amphipods, non-para-

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Atas do Simpósio sôbre a Biota Amazônica

sitie Isopods, shells, and snails

with calcareous cases is probably

due to both of these factors like-

wise. The only molluscs available

are small Ferrissidae with conchio-

lin cases, which biologically do not

act a part. The animais living in

these streams, as far as they do not

lead a predaceous life, feed on the

organic substances fallen or con-

veyed into the water, such as flow-

ers, fruits, pollen, dead organisms,

etc., and the produets of their

decomposition .

Of very little importance for the

direct nutrition appear to be the

leaves shed by the trees and con-

tinually falling into the water.

They never show any feeding-tra-

ces caused by aquatic organisms.

Their organic and mechanic de-

composition seems to go on very

slowly in the acid water. It will be

necessary to elucidate their decom-

position and to get to know the

active bactéria and fungi in order

to understand the nutrition of va-

rious animais and the food-chain

of these streams. A large number

the non-predaceous animais are

filtrators, e.g. the larvae of many

Trichoptera, Chironomidae, and

Simuliidae, which constitute the

main part of the invertebrate

fauna. One of the most frequent

Trichoptera is Macronema, which

makes protrude its cases in a

strong current, on spots where the

sand is kept together by a compact

ramification of roots. Its larvae fil-

trate the water by means of nets

whose width of mesh is suitable

for catching bacteriae and spores

of fungi (compare Sattler ) .

Other filtrators, such as the fre-

quent Hydropsychidae (Trichopte-

ra) have less fine nets. The only

aquatic animais that are adapted

at the highest degree to the very

changeable biotope of the lower

course, the so-called Igapó-zone,

are micro-filtrators, namely spon-

ges of the genus Parmula, which

are hanging in the trees a good

number of meters above the low-

-water levei.

Remarkable is the comparatively

high numbers of predaceous insect

larvae. Apart from the numerous

carnivorous Odonata species are

also to be found among the other-

wise generally phytophagous Ple-

coptera, Ephemeroptera, and Lepi-

doptera. The latter feed in the

strong current of cascades on the

larvae of Simuliidae.

A general survey on the fauna

of these streams shows that in the

upper and middle course submer-

sed crustaceous sponges are rare

and Bryozoa almost missing; Tur-

belaria are represented by small

species from different orders,

whilst the greater Tricladida are

rare; Tubificidae are always to be

found in small numbers; Hirudi-

nae, represented by very small

forms, are extremely scarce; Os-

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tracoda, represented only by small

species, and Copepoda are not fre-

quent; Palaemonidae, represented

by a number of species from the

genus Macrobranchium and relat-

ed forms can often be found, but

Atyidae are missing; Mysidacea,

small and transparent animal-

cules, may be easily overlooked;

the biggest invertebrates are re-

presented by the amphibious Po-

tamantidae; the larval stages of

the aquatic insects, represented by

an extremely large number of

species and individuais, constitute

the greater part of the invertebrate

fauna.

Ephemeroptera are frequent and

represented by many specialised

forms. Plecoptera are not nume-

rous, represented only by genera of

the subfamily Acroneurinae. The

larvae of Odonata and Trichopte-

ra are represented by a very big

number of species which are well

adapted to the various biotopes.

Anywhere to be found are Hemip-

tera; on the surface of the water

Gerridae and Veliidae, under the

surface some Naucoridae, Corixi-

dae, Belostomatidae, Notonectidae,

and Ranatra. Apart from the above

mentioned carnivorous Lepido-

ptera there are some rheophile

species case-building or even mi-

hing in Thurnia. Coleoptera are

rare; frequent and rich of species

are Helminthidae and Gyrinidae;

Etytiscidae and Hydrophilidae are

only represented by a few small

species. The group that is richest

of species are here as well as in

other waters Chironomidae. In a

small stream may live side by side

more than a hundred species. Most

of these species are remarkably

small. The majority are Chirono-

minae, particularly of the genus

Polypedilum and of the tribus Ta-

nytarsini. About 15 per cent of the

species belong to the predaceous

Tanypodinae, particularly to the

tribus Pentaneurini and the ge-

nus Coelotanypus. Ceratopogoni-

dae, Tipulidae, and Stratiomyidae

are regularly found in humid or

hygropetric substrata.

There are many fishes, most of

them are small species. In one and

the same stream may be counted

upon 30 to 50 different species, the

majority of which are Characidae,

in addition to these various Silu-

roidea, Gymnotidae, Cichlidae, and

in muddy sections Rivulidae. A big

number of these fishes seem to

feed on emerging insects or fallen

into the water, etc. Outspoken pre-

dators are Hoplia and the Cichli-

dae.

To the stream fauna always be-

long the larvae of frogs or toads,

and also various amphibious li-

zards which by plunging feed on

insect larvae. Furthermore can be

met small specimens of the croco-

dile Jacaretinga trigonus and oc-

casionally also semi-aquatic sna-

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Atas do Simpósio sôbre a Biota Amazônica

TABLE 1

Average from the analysis of 12 different streams in the central

Amazon forests

y/l

20 8,52

pH 4,5

Hufa 28,5

Alkalinity mval/1 . 0,0C9

O 2 saturation 75%

C0 2 free mg/l . . 30,0

Na 1 296

K 1 414

Ca 0

Mg 21

Al 112

Fe 65

Mn 18

N 297

N (N0 3 ) 5,0

P (total) 4,8

Si 2 480

Cl 484

S0 4 26

kes. There seem to be there no

birds which in their mode of life

are confined to the stream biotope.

In a rain-forest stream can be

distinguished two main biotopes,

each with a characteristic fauna

determined by the degree of cur-

rent. Firstly the lenitic region wi-

th slowly moving water (below. . .

20 cm/sec) , where a sedimentation

of drifting organic stuff takes pla-

ce, and secondly the lotic region

with a rheophile fauna which

needs more than 20 cm/sec of cur-

rent. Whilst in the upper course

these two biotopes often change,

one after another occurring at

small distances, with transitory zo-

nes, they find themselves in the

meandering middle course often

side by side. The lenitic bank is

mostly situated opposite the lotic

bounce-bank. Within the lenitic

area flock together near the bank

fine detritus and mudd, which to-

wards deeper water pass over into

thick layers of leaves, which final-

ly change into sand. In and on the

fine mudd leaves a fauna rich of

species that is, however poor of in-

dividuais: Turbellaria, Tubificidae,

Hydrachnidae, Ostracoda, Copepo-

da, Ceratopogonidae, a big number

of Chironomidae, and Coleoptera

of the genera Laccophilus and

Anacaena, small Corixidae of the

genera Micronectis and Tenagobia,

and the digging larvae of the dra-

gon-fly Ophiogomphus. The pure

sand is little inhabited, among

others by some Chironomidae and

Progomphus-larvae. On and among

the leaves live small Hydroptilidae

and the Callamoceratidae Notio-

myis (Trichoptera) ( the big digging

larvae of Potamanthus (Epheme-

roptera) and the flattened larvae

of Hagenia (Odonata) , the Nauco-

ridae Cryphocricos, and Hydrach-

nidae. The density of population

strongly vacillates and lies bet-

ween 0.5 and 10 g/m 2 .

In the lotic area are to be found,

besides sand, only solid substrata,

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105

such as ramifications of roots,

pieces of wood, fixed big leaves,

and occasionally bare Arenite

stone. The current amounts to

30 cm/sec. on an average, on pla-

ces where the stream is restricted

by pieces of wood and roots and

where there is a stronger drop, it

may, however, go up to about 60

to 100 cm/sec, and in small casca-

des even up to 200 cm/sec. The

highest density of population of 15

to 20 g/m 2 will be found in the

flowed through systems of roots of

the banks of the floor. At these pla-

ces can be found various Tricho-

ptera of the genera Psychomyia,

Potamyia, Smicridea, Chimarrha;

and of the families Leptoceridae

and Hydroptilidae. In addition to

these some Ephemeroptera, among

others of the genera Hermanélla,

and various Leptophlebiidae, Odo-

nata of the families Libellulidae,

Calopterygidae, Agrionidae, Lesti-

dae, and the remarkable Euphaea,

and furthermore Elminthidae and

Plecoptera. On solid wood and sto-

nes occur moreover the Trichopte-

ra Protoptila (Glossosomatidae) ,

Marlia (Odontoceridae) , and Heli-

copsyche. At an increased current

velocity of more than 40 cm/sec

the places of the above mentioned

forms are taken by Hydropsychi-

dae, Simulidae, and various species

of the Chironomidae Rheotanytar-

sus . These insect larvae reach the

maximum density of population in

the strongest current of the casca-

des. Among them live as predators

the big larvae of Corydalis , a Li-

bellulidae well adapted to the

ground by its colour, and the above

mentioned Lepidoptera species,

predatorily feeding on Simuliidae.

Where there are some algae on the

stones, there are found in strong

current moreover the larvae of

Baetidae (Ephemeroptera) and Pa-

ragyractis (Lepidoptera), on driz-

zled stones occasionally the Ortho-

cladiinae Cricotopus.

In the transitory area between

water and land lives a Blattidae

species that is active at night. Par-

ticularly near cascades live on the

water levei the gleaming larvae of

a Lampyridae species and the Tri-

choptera Tinodes which spins long

cases.

Wherever in the reverse current

or at surface barriers the organic

substances drifting on the surface

flock together such as fruits, flow-

ers, dead animais, leaves, pollen,

etc., there is a rather inconstant

biotope constituted by this epineus-

ton, where develops within a short

time a characteristic biocoenosis.

It can be quickly destroyed by mi-

nor water levei oscillations. Its sur-

face is always inhabited by Velidae,

as a rule found only there. In the

aquatic area live some small bee-

tles, Nepidae or Belostomatidae,

and the larvae of a Chironomariae,

which after the destruction of its

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Atas do Simpósio sôbre a Biota Amazônica

previous biotope fastens itself to

the water surface by means of a

short thread and hanging on it is

drifted to another accumulation of

epineuston.

The composition of the above

described biocoenosis of the

streams changes, when we leave

the tertiary central area and get to

the adjacent regions, which either

belong to archaic, paleozoic, meso-

zoic formations, or in the foreland

of the Andes to young alluvions.

According to the geological condi-

tions the water is then more or less

rich of nutritive minerais, and pH

is getting up to a neutral order. Al-

gae and aquatic flowering plants,

shells and snails and phytophagous

insect larvae among others are be-

coming frequent. It is therefore

possible to obtain by a biological

analysis of stream biocoenoses in-

formations on the water chemism,

which admits conclusions on the

edaphic and geological conditions

of the tributary region of the

respective watercourse. These well

known relations between the che-

mism of a water and the one of

its tributary area allow by virtue

of the inspections carried out on

these streams to divide the ecolo-

gically apparently homogeneous

area of the Hylea amazônica into

the Central Region which is poor of

nutritive substances, and the Bor-

der Region which is in any case

richer of these substances. The

Border Region, according to its dif-

ferent geological structures can be

subdivided into three zones: (1)

the zone situated to the North and

the South of the Central Region

with its predominant archaic for-

mations of the Guyana and Central

Brasilian shield, which partially is

superimposed by mesozoic layers;

(2) to the East the intermediate

strictly limited palaeozoic “carbo-

nic stripes”, and (3) to the West

the foreland of the Andes with its

brackish (and marin?) sediments

and the young Andine alluvions.

This ecological division of Ama-

zônia which has resulted from the

inspection of streams has been cor-

roborated, as far as it has been pos-

sible to make use of them, by the

biogeographical results of the ter-

restric biotopes.

The ecological structure of the

Amazonian Region becomes, how-

ever, only clear by taking into con-

sideration the fact that this area

poor of nutritive substances is cut

by many big rivers originating in

the border areas and, like the Ama-

zon River itself, partially have dug

wide valleys into the soft tertiary

sediments and have filled them up

with sediments coming from their

tributary regions and incessantly

renewed from there.

These river valleys with their

“Varzea” — landscape have in the

Central Region, but for the same

climate, ecologically nothing in

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Volume 3 (Limnologia)

107

common with the adjacent “Terra

firme”. Their floors correspond to

a large extent in their content of

nutritive substances to those of

the border regions they derive

from, they are foreign to their sur-

roundings (“umraumfremd”) in

Central Amazônia. Those who start

thinking from this condition will

be able to understand the ecology

and biogeography of the Amazon

Area.

SUMMARY

The streams of the “Hylea ama-

zônica” represent an extreme bio-

tope. Their water is very poor in

dissolved minerais. The trees close

over the stream and only a small

part of solar radiation touches the

ground. The temperature is about

24,5 C° with the daily and annual

oscillation of about ± 1 C°. The

lack in minerais and light prevents

plantlife nearly completely. Except

some species of Batrachosperma-

ceae (Rhodophyceae) , algae are

missing. The only phanerogam is

Thurnia sphaerocephala, growing

semi-aquatically. The basic food of

the stream fauna essentially con-

sists of allochthonous organic ma-

terial, washed or fallen in. Caused

by the offered to nutrition and the

chemistry of the water, animais,

typical elsewhere for the biocoeno-

sis of streams, are missing here

completely. For example: mussels

a nd snails — except some Ferrissia

without a calcareous shell — , Am-

phipoda, Isopoda — except para-

sitic ones — . Turbellaria, Oligo-

chaeta, Hirudinaea and Ostracoda

are rare. Larvae of insects, as Ephe-

meroptera, Odonata, Trichoptera

and Chironomidae, are common

and numerous.

Generally a stream can be divid-

ed into three ecological sectors,

the upper course: source- and ero-

sion-zone with relatively strong

gradient, where lenitic and lotic

areas are changing frequently. The

middle course: sedimentation-zo-

ne with a lot of meanders and san-

dy bed.

The lower course: “Igapó”-zone,

determined by the immense annual

oscillation of the water-level of the

main river system. A stream-bio-

coenosis can develop itself only

during a few months of the year.

During the other time the water is

dammed up, forming a type of wa-

ters limnologically not yet defined.

The stream-biocoenosis of the

upper and middle-course shows a

changing composition, depending

on the current velocity. Two main

biotopes can be distinguished by a

characteristic animal-association :

The lenitic biotope — current ve-

locity speed up to 20 cm/sec —

with sedimentation of organic ma-

terial, and the lotic biotope with

stronger current velocity speed and

a rheophilous fauna. The main

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Atas do Simpósio sôbre a Biota Amazônica

substratum for rheophilous ani-

mais is composed of roots and

wood, hanging and lying in the wa-

ter.

Especially in the lower course

roots of epiphytes (Araceae) are

hanging into the water, being of

particular importance, because

they are floating on the surface

even in the time of stagnation. A

very dynamic and isolated biotope

with a characteristic fauna is form-

ed by floating epineuston —

fruits, pollen, dead animais, skins

of emerged insects etc.!

The stream mentioned above is

typical for the Central-Amazon re-

gion, covered by washed-out depo-

sits of sand and clay, which were

accumulated in the tertiary by a

large fresh water lake. Its boun-

dering formations are geologically

different and richer in minerais:

here molluscs are be found.

By the known close connection

among the chemistry of the

streams and the geological and

edaphic facts we can divide the

Amazon region ecologically into

the central region, poor in nutri-

tion, and the heterogenous peri-

pheral regions which are richer in

it. The central and poor region is

cut by the rivers coming from the

bordering regions. Their large

valleys are filled with alluvions

brought from their upper courses,

and they are ecologically strange

in the central region.

REFERENCE

Fittkau, E. J., 1964, Remarks on lim-

nology of central-Amazon rain-

-forest streams. Verh. Intern.

Verein. Limnol., 15: 1092-1096.

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Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 109-115 — 1967

“EUPERA PRIMEI” SP. N. DE LA REGIÓN DEL RIO

UCAYALI, PERU (Mollusca, Pelecypoda)

MIGUEL A. KLAPPENBACH

Museo Nacional de Historia Natural, Montevideo, Uruguay

(Con 3 figuras en el texto)

En América, dei rio de la Plata

al sur de los Estados Unidos, se han

descripto 26 especies de pequenos

bivalvos fluviales pertenecientes a

la familia Sphaeriidae, que actual-

mente son agrupados en el género

Eupera Bourguignat, 1854. Este

género ha sido considerado por nu-

merosos autores como sinónimo dei

más antiguo Byssanodonta D’Or-

bigny, 1846. No obstante, en un

trabajo anterior (Klappenbach,

1960) hemos demostrado que se

trata de dos géneros perfectamente

diferenciados, debiendo restringirse

el uso de Byssanodonta exclusiva-

mente para una pequena almeja

dei rio Paraná, de chamela edén-

tula. Indudablemente ese número

sufrirá modificaciones una vez que

s e realice la revisión dei género y

aunque alguna especie posiblemen-

te deba ser sinonimizada, creemos

que el mismo irá en aumento a me-

dida que se vaya conociendo mejor

la pequena fauna malacológica de

los grandes rios sudamericanos.

Por ello resulta sumamente curioso

el hecho de que las menciones que

hemos podido registrar para la

enorme cuenca amazônica resulten

tan escasas. En una rápida revista

de las especies descriptas para Sud

America, nos encontramos con que

la primera lo fué en época relati-

vamente temprana (Spix, 1827:

32), para el Estado de Bahia, en

Brasil, con el nombre de Cyclas

bahiensis. Luego Anton (1837:

284) describe dos especies de Sud

América, Cyclas maculata y C. mo-

dioliforme. No las figura ni concre-

ta localidades y sus cortas descrip-

ciones no permiten la identifica-

ción de sus especies. Pocos anos

después Haldeman (1841: 53)

describe más brevemente aún su

Pisidium diaphanum sobre un

ejemplar que habria sido encontra-

do (Prime, 1863: 33) en el interior

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110

Atas do Simpósio sôbre a Biota Amazônica

de una gran Pomacea procedente

de Brasil, sin localidad más preci-

sa. No fué figurado y actualmente

(H. B. Baker, 1930: 53) estaria

perdido. Mas tarde Bourguignat

(1854: 663) describe y figura acep-

tablemente Pisidium moquinia-

num, dei centro de América Meri-

dional, sin establecer localidad

más definida. Transcurren vários

anos hasta que Clessin (1879:246/

47) describe su Limosina túmida ,

también de Bahia y cuya ilustra-

ción deja bastante que desear.

Diez anos después Jousseaume

(1889: 257/58) nos hace conocer

una nueva especie de Caracas, Ve-

nezuela, con el nombre de Limosi-

na simoni. Descripción e ilustra-

ción son buenas. F. Baker (1913:

663/64) describe y figura, sin no-

minar, una especie de Eupera dei

lago Papary, en el Estado de Rio

Grande do Norte, Brasil. Pósterior-

mente Doello-Jurado (1921: 73/

75) describe Eupera platensis de

Rio Santiago, Provinda de Buenos

Aires, Argentina, sobre el rio de la

Plata. Luego H. B. Baker (1930:

56/57) aumenta la lista con Eupe-

ra gravis, de Venezuela. Nos cor-

respondió cerraria (Klappenbach,

1962: 102) con Eupera doellojura-

doi de Puerto Platero, Colonia,

Uruguay. Esta es, cronologica-

mente, la última especie dei género

descripta para Sud América. No

entrando a considerar las especies

dei sur, cuenca dei rio de la Plata,

E. platensis y E. doellojuradoi y

prescindiendo de las especies de

Anton y Haldeman, insuficiente-

mente descriptas, no figuradas, to-

talmente imposibles de identificar

y sin localidades típicas concretas,

tenemos para el norte de Sud Ame-

rica cinco especies de Eupera : E.

bahiensis, E. moquiniana, E. túmi-

da, E. simoni y E. gravis; ninguna

de ellas concretamente dentro dei

área amazônica. Constituyen ex-

cepción tres citas de Haas (1949a:

153; 1949b: 307; 1952: 111), las

únicas que hemos podido hallar en

la literatura malacológica, baseada

todas ellas en material colectado

por el Dr. Harald Sioli en locali-

dades de los Estados de Pará y

Amazonas. Estas citas de Haas son

referidas en su totalidade a Eupera

bahiensis (Spix, 1827) . Por nuestra

parte al revisar el material de Eu-

pera existente en la colección dei

American Museum of Natural His-

tory, de Nueva York, encontramos

un numeroso lote no identificado

procedente de la zona dei rio Ucay-

ali, en Perú, que estimamos perte-

nece a una especie nueva, cuya

descripción damos a continuación,

dejando expresa constância de

nuestro particular agradecimento

al Dr. William K. Emerson, Chair-

man y Associate Curator y Sr.

William E. Old Jr., Museum Specia-

list, por su hospitalidad y generosa

cm

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Volume 3 (Limnologia)

111

Eupera primei sp. n., holotipo N.° 1220 Col. Mal. Mus. Nac. Hist. Nat. Monte-

video, largo 7 mm — Fig. 1: Valva izquierda, vista interna; fig. 2: idem, vista

exterior; fig. 3: idem. vista inferior, mostrando la ubicación de los dientes.

cesión de ejemplares. La especie es

nominada en homenaje a Temple

Prime, uno de los primeros especia-

listas en estos diminutos bivalvos.

Eupera primei sp. n.

Diagnósis: Concha diminuta

aunque más bien grande dentro dei

género (7.00 X 6.00 mm). Se ca-

racteriza por su forma oval muy

corta y eje vertical elevado, re-

sultando proporcionalmente muy

alta. Umbones pequenos y charne-

la relativamente débil. Perióstraco

marrón muy claro, con estrias la-

melosas bajas y poco conspícuas.

Holotipo: N.° 1.220 Col Malac.

Mus. Nac. Hist. Nat. Montevideo.

Colector: H. Bassler, fecha; No-

viembre de 1923.

Localidad Típica: Pequino, pró-

ximo al rio Ucayali, Perú.

Medidas (en milímetros) : largo,

7.00; alto, 6.00.

cm l

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Atas do Simpósio sóbre a Biota Amazônica

Descripción: Concha equivalva,

cerrada, inequilateral. Valvas ova-

les, con el eje mayor orientado en

sentido antero-posterior, delgadas

pero de textura bastante sólida

para el tamano. Borde dorsal cor-

to, sub-recto; anterior fuerte y re-

gularmente curvado, se une al in-

ferior en una suave línea descen-

dente. Borde inferior largo, de cur-

va amplia y abierta, se continúa

con el posterior, más corto pero

también ofreciendo una curva muy

regular. Umbones pequenos, proso-

giros, algo desplazados en dirección

anterior. Dientes cardinales sim-

ples en ambas valvas, pequenos,

más bien bajos, colocados inmedia-

tamente por debajo dei umbón; el

izquierdo más grueso y compacto,

el derecho más comprimido for-

mando una pequena lâmina curva

que presenta en su cara inferior

una zona levemente excavada don-

de juega el cardinal izquierdo. Este,

a su vez, presenta en la base de la

cara superior una foseta estrecha

y alargada, para alojamiento dei

cardinal derecho. Los dientes late-

rales, dobles en la valva derecha,

son simples en la izquierda. En ésta

última el lateral anterior se pre-

senta más corto, grueso y elevado,

en forma de triângulo sub-equilá-

tero. El lateral posterior es más

alargado, fino y bastante más bajo.

En la valva derecha los anteriores

son cortos, gruesos, bajos; el supe-

rior más débil, separados por una

fosa alargada, relativamente pro-

funda, para alojamiento dei late-

ral anterior de la valva izquierda.

A su vez los posteriores de la val-

va derecha son un poco más alar-

gados y la fosa que los separa no

es tan profunda, siendo el lateral

inferior más grueso que el superior.

Ligamento algo corto, fino, comien-

za a la altura de los laterales pos-

teriores y se extiende hasta llegar

frente a los cardinales. Superficie

exterior aparentemente lisa, con

dos fuertes estádios de crecimien-

to bien marcados. Bajo fuerte au-

mento es posible observar las es-

trias lamelosas y concêntricas que

forma el fino perióstraco de color

marrón claro y que por transparên-

cia deja ver las manchas pardo vio-

láceas ya conocidas de otras espe-

cies dei género. Superficie interna

amarillenta, deslucida y áspera por

dentro de la línea paleal. Por fue-

ra de esta línea se torna pulida y

brillante, formando una banda so-

bre el borde inferior interno, que

se extiende desde la impresión mus-

cular posterior a la anterior. Las

inclusiones pigmentarias ya men-

cionadas, adquieren en la superfi-

cie interna de las valvas un aspec-

to grumoso, arracimado, en relie-

ve. Impresión paleal entera, visi-

ble. Impresiones musculares tam-

bién visibles, bastante grandes.

Paratipos: Lote N.° 1.309 Col.

Malac. Mus. Nac. Hist. Nat. Monte-

video. 13 ejemplares, igual proce-

cm

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Volume 3 (Limnologia)

113

dencia, colector y fecha que el Ho-

lotipo. Se dan las medidas de cin-

co ejemplares: (en milímetros) .

largo

alto

7.00

5.50

6.00

5.00

6.00

4.75

5.75

4.75

5.50

4.50

Lote N.° 89.158 Col. Malac. Ameri-

can Museum Natural History New

York. Numerosos ejemplares, igual

procedência, colector y fecha que

el Holotipo.

Observaciones sobre Paratipos:

La totalidad de los ejemplares pre-

sentan gran uniformidad en forma,

coloración y aspecto general. Aún

los ejemplares pequenos no ofre-

cen diferencias o variaciones apre-

ciables. Vistos en norma superior,

los dientes laterales de la valva de-

recha no alcanzan a pasar el borde

superior de ésta, resultando invisi-

bles para el observador. En cambio,

los de la valva izquierda sobrepasan

dicho borde, siendo perfectamente

visibles para el observador. En

cuanto a los umbones, estos no ex-

ceden la línea dei borde superior

cuando son vistos en norma late-

ral.

Distribución: Conocida unica-

mente de la localidad típica.

Discusión: De las cinco especies

que hemos seleccionado más arri-

ba como posibles de ser encontra-

das en la cuenca amazônica, pres-

cindiremos de E. túmida, pequena

especie que como su nombre lo in-

dica, presenta un exagerado desar-

rollo en sentido lateral, al punto de

resultar casi cilíndrica. No consi-

derando a E. simoni y E. gravis, la

primera de borde posterior trunca-

do y la segunda de contorno casi

circular y umbones fuertes y altos,

podemos comparar nuestra especie

con E. bahiensis y E. moquiniana.

E. primei difiere de la especie de

Spix, entre otros caracteres, por

sus umbones, que en ésta última

son prominentes mientras que en

aquella resultan pequenos y poco

conspícuos. A su vez la especie que

estamos describiendo es bastante

comprimida lateralmente, resul-

tando su ancho comparativamen-

te mucho menor que en E. bahien-

sis, de la que se puede decir que

es evidentemente abultada. En

cuanto a E. moquiniana, presenta

un borde posterior con un notorio

trunque oblícuo, recto, resultando

sub-angulosa la unión con el bor-

de inferior, mientras que en E. pri-

mei ese borde es regularmente cur-

vado. La primera a su vez también

es de fuerte desarrollo lateral, fren-

te a nuestra especie, que como que-

do dicho, es francamente deprimi-

da. Finalmente E. primei presenta

los pequenos umbones que no ex-

ceden la línea dei borde superior,

mientras que E. moquiniana mues-

tra los umbones sobrepasando di-

cha línea.

3 —

37 121

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Atas do Simpósio sôbre a Biota Amazônica

SUMARIO

Se efectúa una breve revisión de

las especies de Eupera descriptas

para America dei Sur, destacando

las escasas menciones para la cuen-

ca amazônica. Se describe Eupera

primei sp. n., de Pequino, próximo

al rio Ucayali, Perú. Caracterizada

por su forma oval muy corta, eje

vertical elevado, umbones peque-

nos y charnela débil, resultando

facilmente separable de E. bahien-

sis y E. moquiniana, especies estas

últimas con las que es comparada.

SUMMARY

The above presents a brief revi-

sion of the Eupera species describ-

ed for South America, emphasiz-

ing the scarce references register-

ed for the large Amazonian basin.

Eupera primei sp. n. from Pequi-

no, near Ucayali river in Peru is

described. Characterized by its very

short oval outline, small umbos

and weak hinge, it is easily sepa-

rable from E. bahiensis and E. mo-

quiniana, with which species it is

compared.

BIBLIOGRAFIA

Anton, H. E., 1837, Diagnosen einiger

neuen Conchylien-Arten. Arch.

Naturg., 1 (3) : 281-286.

Baker, F., 1913, The Land and Fresh-

Water Mollusks of the Stanford

Expedition to Brasil. Proc. Acad.

Nat. Sei. Philadelphia, 65: 618-672,

pis. XXI-XXVII.

Baker, H. B., 1930, The Mollusca col-

lected by the University of Michi-

gan-Williamson Expedition in Ve-

nezuela, VI. Occ. Paper s Mus. Zool.

Univ. Michigan, 210: 1-94, pis.

XXVII-XXXIII.

Bourguignat, J. r„ 1854, Aménités Ma-

lacologiques, XVIII, Description

d’une éspece nouvelle du genre

Pisidium. Rev. Mag. Zool, (2), 6:

663-664, pl. XIV.

Clessin, S„ 1879, Systematiches Con-

Chylien-Cabinet, Die Familien der

Cycladeen, 9 (3) : 1-282.

Doello- Jurado, m., 1921, Una nueva

especie de “ Eupera ” dei rio de la

Plata. Physis, 5: 72-75, 1 fig.

Haldeman, S. S„ 1841, Descriptions of

four species of Cyclas, three of

which belong to the subgenus Pisi-

dium: and two species of Cypris.

Proc. Acad. Nat. Sei. Philadelphia,

1 (1): 53.

Haas, F„ 1949a, Land und Susswasser-

mollusken aus dem Amazonas-Ge-

biete. Arch. Moll, 78 (4/6) : 149-

-156, pl. 7.

Haas, F., 1949b, On Fresh Water Mol-

lusks from the Amazonian Region.

An. Inst. Biol. Mex., 20: 301-314, 6

íigs., l mapa.

Haas, F., 1952, South American Non-

Marine Shells: Further Remarks

and Descriptions. Fieldiana, Zool.,

34 (9) : 107-132, 26 figs.

Joüsseaume, F., 1889, Voyage de M.

Eugene Simon au Venezuela. Mol-

lusques. Mem. Soc. Zool. France, 2:

232-259, pl. IX.

Klappejíbach, M. A.. 1960, Uber die Gat-

tungen Byssanodonta und Eupera.

Arch. Moll, 89: 141-143, abb. 1-4.

cm

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10 11 12 13 14 15 16

Volume 3 (Limnologia)

115

Klappenbach, M. A., 1962, Una nueva

especie de “Eupera” (Moll., Pelecy-

poda) dei Uruguay. Rev. Mus. Arg

Cien. Nat. B. Rivadavia, Zool., 8

(8) : 101-106, figs. 1-3.

Orbigny, A., 1846, Voyage dans VAme-

rique Meridionale. . Mollusques,

V, (3): 489-710.

Prime, T„ 1863, Monograph of the

Species of Sphaerium of North and

South America. Proc. Acad. Nat.

Sei. Philadelphia : 28-37.

Spix, j. b„ 1827, Testacea Fluviatilia

quae in itinere per Brasiliam . . . :

1-36, pis. I-XXIX, Leipzig.

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 117-125 — 1967

PODZOL SOILS: A SOURCE OF BLACKWATER RIVERS

IN AMAZÔNIA

H. KLINGE

Hydrobiological Institute of the Max-Planck-Foundation, .

Plõn/Holstein, Germany

Acidic freshwater of brownish

colour which is due to dissolved or

suspended organic matter of al-

lochthonous origin, is commonly

referred to as ‘blackwater’ (Sch-

neider, 1961).

Blackwater rivers are a typical

feature of the humid tropical belt.

They occur also in non-tropical re-

gions. It is a well known fact that

blackwater rivers flow from both

peat and swamp soils. But relati-

vely littie is known about podzol

soils commonly associated with

blackwater rivers, in the tropics.

The reason why tropical podzols

have been neglected so far is no

doubt the low agricultural poten-

cial of these soils.

PODZOLS

The Russian word podzol is

^eaning ‘soil under ash’ and is ap-

Püed to acid raw humus soils the

e ssential process of which is term-

ed podzolization, i.e. destruction of

both primary and clay minerais,

and translocation of sesquioxides

and/ or humus from the topsoil

into the subsoil (Anon., 1964;

Mura, 1961).

The topsoil of podzols consists

of an organic matter layer over a

bleached quartz sand layer. In the

subsoil, organic matter, sesqui-

oxides, or both are accumulated .

Tropical podzols being often

identical with ‘white sandy soils’

or ‘bleached sands’ are soils which

show a bleached layer of white

quartz sand which may attain a

thickness of several meters, below

the surface humus layer. The raw

humus at the soil surface may be

absent, due to its destruction by

erosion or agricultural and other

practises of man. The white sand

layer which gave the name to the

above white sandy soils is due to

bleaching and is followed by the

cm l

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Atas do Simpósio sóbre a Biota Amazônica

accumulation zone. This accumu-

lation horizon may be endurated

and is referred to as ortstein, pan,

or coffee rock, the latter expression

being mainly used by Australian

authors .

If in the formation of podzols

groundwater fluctuations are in-

volved the soils are referred to as

groundwater podzols, hydromor-

phic podzols, gley podzols, or

aquods; groundwater podzols of

the tropics are thermaquods; pod-

zols without groundwater influ-

ence are normal or well drained

podzols (Anon., 1960) .

Commonly, ‘lowland tropical

podzols’ — a term proposed by Ri-

chards (1941) to distinguish tro-

pical podzols of low elevation from

tropical mountain podzols and

non-tropical podzols as well have

developed from quartz sandy mo-

dem deposits accumulated by ma-

rine or river actions.

The vegetation of lowland tropi-

cal podzols differs characteristical-

ly from the normal tropical rain

forest (Richards 1957) and is con-

sidered to be an edaphic climax of

the latter. Heath forest, kerangas,

and padang as well of Australasia,

wallaba forest and muri bush of

northern tropical America, caatin-

ga forest of the Rio Negro, campi-

na forest, and certain campos of

the Lower Amazon are plant com-

munities which growing on low-

land trop>cal podzols are charac-

terized by the tendency of one or

some plant species towards domi-

nance (Richards, 1945) .

Bakker (without year) gives

some reasons of extreme bleaching

of soils, under tropical environ-

mental conditions. One of them is

the extreme acidity of leaf extract

and litter of certain tropical plant

species.

DISTRIBUTION OF TROPICAL

PODZOLS

The distribution of lowland tro-

pical podzols shows a remarka-

ble geographic pattern (Klinge,

1965a). After D’Hoore (1964) they

are rare in África where they occur

in small patches. They have devel-

oped from both Coastal sandry se-

diments along the east and west

coast of this continent, and from

river sediments, and at few places

in the Congo basin; they are also

known to exist on the islands of

Mafia and Madagascar. Most Afri-

can blackwater rivers, however,

flow from moor and swamp land.

In Australasia (Dudal & Moor-

mann, 1964) where lowland tropi-

cal podzols are often associated

with swamps and peat formation,

they partially occupy extent areas.

These podzols are known to occur

in the Mekong basin, eastern Ma-

lay Península, upon Borneo, New

Guinea, and some other Indone-

sian islands as well, in tropical and

cm

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Volume 3 (Limnologia)

119

subtropical Australia, and upon

the North Island of New Zealand.

Seepage of podzol areas is of the

blackwater type (Dudal & Moor-

mann, 1964; van Steenis, 1957) .

Lowland tropical podzols of Ame-

rica are reported from Florida and

the Guianas as well where they

occur in areas of relatively large

extent. Podzols have been describ-

ed from some of the Antilles and

eastern Central America. In the

Amazon basin where lowland tro-

pical podzols are widespread they

occupy small isolated patches. Low-

land tropical podzols are always

associated with blackwater rivers,

but these rivers flow also from

peats and swamp soils, mainly in

Florida and the Guianas.

Podzols of mountains within the

tropical belt have been reported

from all continents and are bound

to acid rocks, or impeded drainage,

and to cool humid climatic condi-

tions as well.

UNESCO, within its Humid Tro-

pics Research Programme, is ac-

tually preparing a symposium on

tropical podzols, their vegetation,

and blackwater rivers associated

with these soils.

PODZOLS OF TROPICAL SOUTH

AMERICA

In tropical South America pod-

zols are known to exist in both low-

lands and uplands.

Podzols occur at some places of

the Coastal regions of Colombia

and Brazil as well.

There is no literature on podzols

of the Orinoco basin. Rather detail-

ed informations, however, are

available on lowland tropical pod-

zols of the Coastal plains in Suri-

name, British and French Guiana

as well.

There are only few informations

on podzols in western Amazônia

including the eastern parts of Co-

lombia, Ecuador, Peru, and Boli-

via. Ellenberg (1959; 1964) report-

ed shortly on these soils which

were observed in the surroundings

of Iquitos, Peru, and Wright

(1964) described a mature soil

trending towards a tropical gley

podzol, from eastern Bolivia.

Grubb. et al. (1963) referred brief-

ly to soils which show similarities

with podzols of temperate regions,

in Ecuadorean Amazônia.

Podzols of Brazãlian Amazônia

are dealt with in the subsequent

chapter.

Mountain podzols have been re-

ported from the Andes and the

Guiana Highlands as well.

LOWLAND TROPICAL PODZOLS

OF BRAZILIAN AMAZÔNIA

The relationship between black-

water rivers and podzols of Ama-

zônia is not touched in the pre-war

literature. But Sioli (1954; 1956),

cm l

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Atas do Simpósio sôbre a Biota Amazônica

in papers on blackwater rivers of

the Upper Rio Negro, pointed out

that these rivers flow from sandy

wet soils (not studied by the au-

thor) covered with caatinga forest

(Hueck, 1966; Rodrigues, 1961;

Takeuchi, 1962). The fact that

these blackwaters contained free

aluminum which never before were

found in any other Amazonian ri-

ver water, induced the conclusion

that the aluminum content of the

blackwater is due to the breakdown

of aluminum silicates in the sandy

soils from which the blackwater

flows and that podzolation is going

on in these soils.

The association of blackwater ri-

vers and white sandy soils has been

already observed by Spruce (1908)

and others.

The pedologist who first studied

Amazonian podzols appears to be

Day (1961). He described both very

sandy groundwater podzols devel-

oped on Quaternary sediments un-

der poor to imperfect drainage con-

ditions, and well drained Pará pod-

zols which are more of academic

interest than of any agricultural

value. Some data on both types of

podzols are tabulated below.

TABLE 1

Groundwater podzols and Pará podzols of Amazônia (After Day, 1961)

Groundwater podzols

Pará podzols

Relief

Levei to gently sloping, low lying

terraces.

Fiat to gently sloping or undulat-

ing.

Drainage

High water table. Natural drainage

is poor. Run-off of surface water

is slow.

Excessivo.

Vegetation

Poor to very poor forest.

Brushes and low trees.

Use

Essentially non agricultural soils of

very low fertility.

Extremely low fertility and water-

holding capacity limit the agri-

cultural usefulness of these soils.

Distribution

In small drainage-ways. Probably

widespread throughout the Lower

Amazon. Of very limited extent

in any individual unit and total

area is relatively small.

Observed in two loealities in the

Lower Amazon (near Belém,

Pará, and north of Macapá,

Territory of Amapá).

In 1962, several authors have nian soils, inclutíing some podzols

reported on Amazonian podzols. under caatinga and campina fo-

Klinge published data on carbon rests, and wet campos as well. Sio-

and nitrcgen contents of Amazo- li & Klinge discussed relations be-

cm

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10 11 12 13 14 15 16

Volume 3 (Limnologia)

121

tween podzols, blackwater rivers

and podzols vegetation, especially

of the Rio Negro. Vieira & Santos

described a groundwater podzol of

the surroundings of Breves, Pará,

giving also some analytical data

on this soil. Vieira & Filho discuss-

ed results of soil investigations

performed in caatingas of Uaupés,

the soils being described as podzo-

lic regosol, on brown soils of gra-

nitic origin, and regosol, both de-

veloped from sandy river sedi-

ments.

Falesi (1964) described podzols

of the Zona Bragantina, Pará, and

Klinger & Ohle (1964) reported

on Chemical properties of both soils

and waters, in Amazónia.

Recently, Altemüller & Klinge

(1964), and Klinge (1965 b) de-

scribed catenary soil sequences in

which giant podzols occur, from

the Manaus area. The catenas were

found on slopes of small valleys

drained by blackwater rivers. The

giant podzols occupying the lowest

sites of the catenas are characte-

rized by a few meters deep bleached

sand layer and a remarkable thin

humic cemented ortstein as well.

The thin ortstein is suggested to

be related to lateral percolation of

rain water which carries away the

organic matter migrating through

the podzol profile. The mobil or-

ganic matter, subsequently, passes

into the creeks and so doing deter-

mines the characteristics of the

blackwater.

Blackwater rivers have been re-

lated to lateral percolation on pod-

zols, in other tropical countries too

(Dames, 1962; Dost, 1964).

RELATIONS BETWEEN

TROPICAL PODZOLS AND

BLACKWATER

Since von Humboldt (1860) re-

ported on blackwater rivers of

equatorial South America, and

Muntz & Marcano (1888) dis-

cussed the origin of blackwater co-

lour, literature on black-water in

South America has grown much,

and many theories about blackwa-

ter rivers and the colouring sub-

stances as well have been for-

warded .

Koch-Grünberg (1909) reported

on Indian talks in which the colour

of blackwater rivers is explained by

extracts of the salsaparilla plant.

( Smilax ) .

After Beebe (1927) the colour is

mainly caused by staines derived

from the leaves of the Wallaba tree

( Eperua falcata Aubl.) The same

explanation was given by Davies

& Richards (1933).

De Civrieux & Lichy (1950), in

a brief historical summary of opi-

nions about blackwater and its co-

lour, referred to von Humboldt

who reported on thick grass mats

and roots of salsaparilla (Smilax),

cm l

SciELO

LO 11 12 13 14 15 16

122

Atas do Simpósio sóbre a Biota Amazônica

as sources of the staines; von Hum-

boldt gave notice too on Upper Ori-

noco Indians who believed that the

staines are extracts of the moriche-

to palm. De Civrieux & Lichy

themselves supposed that the key

to solve the problem is in the

swamp forests from which black-

water rivers flow.

By other authors (Huber, 1906,

Sioli, 1956) the opinion was ex-

pressed that blackwater rivers ori-

ginate in the so-called igapó fo-

rests which accompany many

Amazonian blackwater rivers.

In tropical and non-tropical re-

gions as well, blackwater rivers are

known to flow from peat soils. In

these cases the colour of the water

is due to organic matter derived

from the peat.

There are, however, tropical

blackwater rivers flowing from

poázol soils. The following facts

speak in favour of a genetic rela-

tionship between both podzols and

blackwater:

I) Blackwater rivers may be in-

timately associated with pod-

zols growing specific forest ty-

pes, in Amazônia and other

tropical South America as

well, mainly the Guianas

(Bleackley & Khan, 1963),

and others) . This association

has been observed too by geo-

graphers, botanists and limno-

logists as well, in the tropical

belt (cf. Proc. Unesco Sympo-

sia held at Abidjan, Tjiaw and

Kuching) .

II) The blackwater character of

groundwater in podzols soils

points on a genetic relation-

ship between both the soils

and the water, in the tropics

(van Steenis, 1935 a; 1935 b;

1957) .

III) The observa tion that the co-

lour of blackwater becomes

more intensive when it rains

after a period of droughtiness,

is supposed to be related to

the outflow of dark coloured

groundwater which subse-

quently is diluted by further

rain.

IV) Podzol ortsteins the thickness

of which does not correspond

to that of the bleached sand

horizons, are found at sites

where drainage is mostly la-

teral, and have been described

from Amazônia (Klinge,

1965 a) , and the Guianas

(Bleackley & Khan, 1963;

Dost, 1964) as well.

This communication based more

on literature studies than on field

or laboratory work may be con-

cluded with a reference to Richards

(1957) who wrote:

“Blackwater’ streams are also

found flowing from Tropical moor

forest (peat swamp), but where no

cm

SciELO

10 11 12 13 14 15 16

Volume 3 (Limnologia)

123

extensive swamps are known to

exist ‘blackwater’ is a trustworthy

guide to the presence of bleached

sands.” As said above, these bleach-

ed sands are often to be classi-

fied as podzols, from the pedolo-

gical point of view.

SUMMARY

The intention of this literature

review is to point on the very strik-

ing association of blackwater ri-

vers and podzols under specific

plant communities which is known

since the first naturalists traveled

through the humid tropical belt.

After defining the pedological

terms podzol, tropical podzol, and

lowland tropical podzol as well, the

distribution of lowland tropical

podzols and their association with

blackwater rivers in África, Ame-

rica, and Australasia are regarded.

Special reference is made to

Amazônia and its Brazilian portion

from where podzols have been re-

ported in recent years. These pod-

zols are found under both caatinga

and campina forests, and wet cam-

pos as well, and are always asso-

ciated with blackwater rivers.

It is well understood that black-

water rivers flow from peat and

swamps, in tropical and non-tropi-

cal countries as well. There is no

doubt, however, that blackwater

rivers originate in podzol areas, in

the humid tropics. Some facts

which point on a genetic relation

between both blackwater rivers

and podzols are tabulated.

REFERENCES

Altemüller, H. J. & Klinge, H„ 1964,

Mikromorphologische Untersuchun-

gen iiber die Entwicklung von Pod-

solen im Amazonas-becken. In:

Soil Micromorphology (A. Jonge-

rius ed.) Amsterdam, Elsevier, p.

295-305.

Anon., 1960, Multilingual vocabulary of

soil Science. G. V. Jacks, R. Traver-

nier, D. H. Boaleh (ed.) Rome, FAO

2nd ed. 430 p.

Anon., 1964, Preliminary definition, le-

gend and correlation table for the

soil map of the world. World Soil

Resources Reports, 9: 74 p.

Beebe, W., 1927, Studies on a tropical

jungle. Zoologica, N. Y„ 6: 5-193.

Bleackley, D. & Khan, E. J. A., 1963,

Observations on the whitesand

areas of the Berbice formation,

British Guiana. J. Soil Sei., 14 (1) :

44-51.

DE CIVRIEUX, M. & Lichy, R., 1950, Es-

tado actual dei problema de las

coloraciones observadas en águas

ecuatoriales de Venezuela. Boi.

Acad. Cien. fis., Caracas, 13 (40) :

19-36.

Dames, T. W. G., 1962, Soil research in

the economic development of

Sarawak. FAO Rep. no. 1512.

Davies, T. A. W. & Richards, P. W.,

1933, The vegetation of Moraballi

creek, British Guiana. J. Ecol., 21

(2): 350-384.

cm l

SciELO

L0 11 12 13 14 15 16

124

Atas do Simpósio sôbre a Biota Amazônica

Day, T. H„ 1961, Soil investigations

conducted in the Lower Amazon

valley. FAO Rep. no. 1395.

Dost, H„ 1964, Soil conditions and soil

classiíication in Surinam. Abstr.

8th Int. Congr. Soil Sei. 5: 30-33.

Dudal, R. & Moormann, F. R., 1964,

Major soils of Southeast Asia. J.

Trop. Geogr., 18: 54-80.

Ellenberg, H„ 1959, Typen tropischer

Urwàlder in Peru. Schweiz. Z.

Forstwes., 3: 169-187.

Ellenberg, H., 1964, Stickstoff ais Stan-

dortfaktor. Ber. dtsch. bot. Ges., 67

(3): 82-92.

Falesi, I. C., 1964, Levantamento de re-

conhecimento de talhado dos solos

da Estrada de Ferro do Amapá.

Boi. tec. Inst. Pesq. Exp. agropec.

Norte, 45: 1-53.

Grubb, P. J„ Lloyd, J. R., Pennig-

ton, T. D. & Whitmore, T. C„ 1963,

A comparison of montane and low-

land rainforests in Ecuador. I. J.

Ecol., 51: 567-601.

Huber, J„ 1906, La végétation de la

vallée du Rio Purus (Amazone).

Buli. Herb. Boissier, 6 (4) : 249-276.

Hueck, K., 1966, Die Wãlder Südame-

rikas. 422 p., Stuttgart. Fischer.

D’Hoore, J. L., 1964, La carte des sois

d’Afrique au 1/5.000.000. Lagos.

C.C.TA. Publ. no. 93.

von Humboldt, a., 1860, Reise in die

Aequinioctial-Gegenden des neuen

Continents. Vol. 3. Stuttgart, Cotta.

Klinge, H., 1962, Beitrâge zur Kenntnis

tropischer Bõden. V. Z. Pfl-Ernãhr.,

Düng-Bodenk., 97 (2): 106-118.

Klinge, H., 1965a, Report on tropical

podzols. Paris, UNESCO. 139 p.

(Under press.)

Klinge, H., 1965b, Podzols soils in the

Amazon basin. J. Soil Sei., 16 (1) :

95-103.

Klinge, h. & Ohle, W., 1964, Chemical

properties of rivers in the Amazo-

nian area in relation to soil con-

ditions. Verh. int. Verein. theor.

angew. Limnol., 15 (2) : 1067-1076.

Koch-Grünberg, T„ 1909, Zwei Jahre

unter den Inãianern. Berlin, Vol. I.

Muir, A., 1961, The podzol and podzolic

soils. Adv. Agron., 13: 1-56.

Muntz, A. & Marcano, V., 1888, Sur les

eaux noires de régiones équatoria-

les. C. R. A.cad. Sei. Paris, 107 (14) :

908-909.

Richards, P. W., 1941, Lowland tropical

podzols and their vegetation. Na-

ture, 148 (3774): 129-131.

Richards, P. W., 1945, The floristic

composition of primary tropical

rain forest. Biol. Rev., 20: 1-13.

Richards, P. W., 1957, The tropical rain

forest. Cambridge, University Press.

Reprint of the 1948 ed. 450 p.

Rodrigues, W. A., 1961, Aspectos fitos-

sociológicos das caatingas do Rio

Negro. Boi. Mus. Paraense “Emílio

Goeldi”, n.s„ Bot. no. 15.

Schneider, S„ 1961, Synonyma-Liste

“Moor und Torf”. Torfnachrichten,

12 (7/8): 1-61.

Sioli, H„ 1954, Gewásserchemie und

Vorgange in den Bõden im Ama-

zonasgebiet. Naturwissenschaften,

41 (19): 456-457.

Sioli, H., 1956, As águas da região do

Alto Rio Negro. Boi. téc. Inst. agron.

N„ 32: 117-155.

Sioli, H. & Klinge, H„ 1962, über

Gewásser und Boden des brasilia-

nischen Amazonasgebietes. Erd.

Berl., 92 (3) : 205-219.

cm

SciELO

10 11 12 13 14 15 16

Volume 3 (Limnologia)

125

Spruce, r., 1908, Notes of a botanist on

the Amazon and the Andes. Lon-

don, Macmillan, 2 vols.

van Steenis, C.G.G.J., 1935a, Maleische

vegetatieschetsen. I. Tijdschr. K.

ned. aardrijksk. Genoot, (2) 52:

25-67.

van Steenis, C.G.G.J., 1935b, Maleische

vegetatieschetsen. II. Tijdschr. K.

ned aardrijksk. Genoot., (2) 52:

171-203.

Van Steenis, C.G.G.J., 1957, Outline of

vegetation types in Indonésia and

some adjacent regions. Proc 8th

Pacif. Sei. Congr. 1953, 4: 61-97.

Takeuchi, M., 1962, The strueture of the

Amazonian vegetation. IV. J. Fac.

Sei. Tokyo Univ. Section 3, Bot., 8

(2): 27-35.

Vieira, L. S. & Santos, W. H., 1962, Con-

tribuição ao estudo dos solos de

Breves. Boi. téc. Inst. agron. N., 42:

33-55.

Vieira, L. S. & Filho, J.P.S.O., 1962, As

caatingas do Rio Negro. Boi. tec.

Inst. agron. N., 42: 7-32.

Wright, A.C.S., 1964, Report on the

soils of Bolivia. World Soil Resour-

ces Reports, 10: 54 p.

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 127-140 — 1967

THE ARTIFICIAL BROKOPONDO LAKE OF THE

SURINAME RIVER. ITS BIOLOGICAL

IMPLIC ATION S

P. LEENTVAAR

State Institute for Nature Conservation Research (Rivon),

Zeist, The Netherlands

(With 6 text-figures, 1 map and 3 graphs)

On February 1, 1964, the dam

across the Suriname River at Afo-

baka (Surinam) was closed and

the artificial Brokopondo Lake be-

gan to fill. The lake will ultimate-

ly cover an area of 1.500 km 2 tro-

pical forest and the water is being

used for hydroelectric purposes. At

the end of 1963 a team of four bio-

logists were enabled by the Nether-

lands Foundation for the Advance-

ment of Research in Surinam and

the Netherlands Antilles (Wosu-

na) to study the alterations in

plant and animal life in the lake

region. The work is being carried

out under the auspices of the Ne-

therlands Foundation for Scienti-

fic Research in Surinam and

the Netherlands Antilles (“stu-

diekring”) . Hydrobiological re-

search was started some months

before the closure of the dam by

P. Leentvaar and continued at pre-

sent by J. V. D. Heide. The bota-

nist, Dr. J. Van Donselaar carries

out botanical inventarisation. Ich-

thyological inventarisation is being

carried out by various investiga-

tors. Few biological data were

known from the river before the

closure and the available time un-

til the dam was closed was short;

consequently our knowledge of

plant and animal life before the

changing of the environment is

scarce. A few trips on the river and

regular sampling at Pokigron in

the upper course, yielded an im-

pression of the undisturbed river.

The description of the river is

of interest for comparison with

tributaries of the lower Amazon ba-

sin which rise also in the Guiana

highlands. The Suriname River

and its tributaries Pikien Rio and

Rivon communication nr 234.

128

Atas do Simpósio sobre a Biota Amazônica

Gran Rio rise in the highlands of

Guiana just north of the Brasilian

border. The river flows northward

through tropical rainforest. The ri-

verbed is rocky. Trees border the

river, but neither swampy vegeta-

tion nor areas with stagnant wa-

ter occur along the banks. The wa-

ter flows swiftly where rapids and

falis are present. Between these

obstacles the river flows, sluggish-

ly. The river carries little silt and

there is practically no mud at the

bottom. Sand flats are visible at

dry times. The water is poor in mi-

nerais, as is shown by the low elec-

tric conductivity of about 20uS.

The pH is about 6.5 and the wa-

ter is almost saturated with oxy-

gen. The temperature varies bet-

ween 28 and 30°C. The transparen-

cy, measured with the Secchi-disc,

is about 1 . 5 meters. The colour of

the water is greyish-brown; it ori-

ginates from brown particles sus-

pended in the water and not from

dissolved humic substances. There

is a high amount of silica and some

iron. In small, shallow tributaries,

such as the Sarakreek (map), the

turbidity of the water is higher

and more iron is present; the elec-

tric conductivity is higher, the oxy-

gen content is lower and the tem-

perature is also lower due to sha-

dow by trees. The colour of the wa-

ter is turbid-brown. For the Ama-

zon basin Sioli (1964) distin-

Fig. 1 — The barrage in the Suriname River at Afobaka, with dead trees in the

lake (June 1964).

cm 1

SciELO

130

Atas do Simpósio sôbre a Biota Amazônica

The total mass of organisms and

also of plankton is low. Therefore

it is surprising, that the river is

comparatively rich in fish. The

food Chain of the fish is not clear;

probably some of the fish feed on

the relatively numerous shrimps,

but several species prey on other

fish.

River conditions vary in the dry

period and the rainy period. Ac-

cording to weekly observations at

Pokigron in the upper course of

the river, the water levei is fairly

stable from December until March.

In the last week of May, the main

rainy season starts and the water

levei rises about 2 meters for a pe-

riod of two months. In the dry sea-

son plankton is developing but

soon after the beginning of the

rains, this plankton is washed

downstream. Plankton catches ire

composed now of species, which

occur in tributaries; when the

rains last long practically no more

plankton is found. Therefore, du-

ring the months of July and Au-

gust, pure water flows down the ri-

ver. At this time the pH and elec-

tric conductivity of the water are

lowest. This seasonal fluctuation

Fig. 3 — Growth of filamentous algae in quiet parts of the lake, between

inundated trees, near the village Koffiekamp (July 1964).

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CHEMICAL ANALYSES ANO WATER LEVEL OF THE SURINAME RIVER AND THE BROKOPONDO LAKE IN 1963 AND 1964

ÍN

Volume 3 (Limnologia)

131

Fig. 4 — Suriname River near the village Koffiekamp in the dry season

< January 1964).

in plankton and mineral content

in the flowing river affected con-

ditions in the expanding lake,

when the water entered this lake.

After the closure of the dam ob-

servations were started at 2 of the

future 10 sampling stations. The

following data concern only these

two stations, (until September

1964) located at Afobaka near the

dam in the midst of the river and

in the Sarakreek inside the forest.

As is shown in graph 2, the wa-

ter levei rose quickly. The gauges

are given in NSP = New Surinam

Levei. During the short rain in

March and in the long rainy pe-

riod following the end of May the

rise in levei was accellerated. In the

same graph the surface values are

given of oxygen, temperature, pH,

electric conductivity and transpa-

rency measured with the Secchi-

disc. The differences between Suri-

name River and Sarakreek before

the closure are easily detected in

the graph. Soon after the closure

the water stagnated at both sta-

tions and a Sharp drop in oxygen

content occurred. At Sara the

exhaustion was greater as more de-

caying organic matter was present

and stagnation was enhanced by

lack of wind between the trees. In

Sara station for several weeks no

oxygen was found from top to bot-

132

Atas do Simpósio sobre a Biota Amazônica

tom. After 18 March 1964 the oxy-

gen content increased again, but

only in the upper 3 to 4 meters.

Two periods of increasing oxygen

content are obvious, especially in

the curve of Sara . The first

increase occurred during the dry

time of April and May; the second

during the prolonged rain period

after June. In September both

stations obviously became equal in

oxygen content. At this time more

open space appeared between the

trees by the rising water levei at

Sara, even more, by the total inun-

dation of trees. As a consequence

the improved illumination of the

water surface favoured oxygen

proàuction by the plankton. Also

the temperature increased, but the

temperature at Sara — more sha-

dowy by trees — remained about

two degrees lower than at Afoba-

ka. Higher temperatures were

found at the surface of the stag-

nant water than in the flowing

stretches. At Afobaka the maxi-

mum temperature recorded was

about 35° C. Temperature and

oxygen were fluctuating strongly

during the day in the stagnant

water (graphs 3 and 4). The trans-

parency of the water at Sara in-

creased more than at Afobaka, de-

Fig. õ — Grmcth of waterhyacinth in the lake (August 1964).

BROKOPONDO BARRAGE LAKE NEAR AFOBAKA

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Volume 3 (Limnologia)

133

Fig. 6 — The dry riverbed below Afobaka, after the closure of the dam

f February 1964).

monstrating the greater stagnation

in the water between the totally

drowned trees. During the rain

time the transparency increases

and the electric conductivity de-

creases by dilution . In dry times

the electric conductivity increas-

ed gradually. In deeper water

layers an increasing amount of

minerais was found, as is shown in

graph 3 in which curves are plot-

ted for each depth. The fluctua-

tions in the deeper water are great-

er. After stagnation the pH drop-

ped to about 5.5 at both stations;

in graph 3 it is clearly visible, that

a fluctuation of short duration

occurred at the beginning of each

rain time, in all water layers. The

lower pH found after stagnation

may be caused by the larger

amount of CO- derived from decay-

ing material and also from dissolv-

ed humic substances, which now

made their appearance in the

water. The colour of the water

turned to light brown. Iron was

precipitated and could be found

suspended near the anaerobic zone

at 3 or 4 meters. In the anaerobic

deeper water the amount of dis-

solved iron increased and the same

was true with regard to phosphate.

Also H-S was formed .

The said physical and Chemical

alterations in this aquatic environ-

134

Atas do Simpósio sôbre a Biota Amazônica

ment strongly affected plant and

animal life. It is hardly possible

to indicate which of the factors

had the strongest influence on the

biocommunity. The absence of flow

caused a Chain of alterations of

which the change in oxygen con-

tent is the most important. This

is illustrated by the general obser-

vation, that in the flowing river

the oxygen content was higher at

night than at daytime and that

in the stagnant water of the lake

the oxygen content at night was

considerably lower than at day-

time. The oxygen metabolism in

the river is abiogenie. Differences

in temperature rule the oxygen

content in the diurnal cycle since

plant and animal life is scarce in

the river. Oxygen production and

consumption in dark and light

bottles could hardly be measured

by the paucity of plankton. In the

lake oxygen was found in an up-

per layer where the ligth penetrat-

ed; the present larger amount and

other species of plankton produ-

ces sufficient oxygen at daytime.

At night the oxygen content drop-

ped sharply by respiration activity

and by the presence of large

amounts of reducible substances

(see graph 4).

The differences in temperature

in the diurnal cycle cause conver-

sions in the upper layers only. The

effect of insolation is restricted to

the upper 2 . 5 meters of water (see

further Leentvaar, 1966) . Braun

(1952) found instable thermocli-

nes at 2-3 meters in shallow lakes

in the Amazon region.

As mentioned above, the river

plankton was composed mainly of

diatoms and desmids. The most

frequent diatom was Eunotia aste-

rionelloides; other species were Mc-

losira sp., Rhizosolenia spp. and

Surirella spp. After closure the ri-

ver plankton could not exist any

longer; it became succeeded by a

transitional plankton and even-

tually by a more stable “lake

plankton”. In the transitional pe-

riod, when the oxygen decreased in

all layers, the diatom Eunotia dis-

appeared and also other species

from the river plankton. Other ele-

ments such as Eudorina elegans

developed in great numbers and

the water got a green colour. Thus

the transitional zone (period)

could be detected by its colour; as

the lake area expanded southward

a green “wave” of the transitional

zone also moved southward .

Other elements in this plankton

were Cyclops, Diaphanosoma and

rotifers. In special cases and tem-

porarily the organisms of the tran-

sitional zone also developed strong-

ly in the flowing river, i.e. during

disturbances, occurring at the be-

ginning and at the end of a rainy

period. It is an example of selfpu-

BROKOPONDO BARRAGE LAKE - DAILY OBSERVATIOIMS (1964 )

Volume 3 (Limnologia)

135

rification of the river under natu-

ral circumstances. The permanent

disturbance caused by the dam

interrupted the normal cycle and

the community was succeeded by

plankton, composed of many uni-

cellular flagellates ( Trachelomo -

nas, Strombomonas) and nume-

rous crustaceans and rotifers, oc*

curring only in the oxygenated 3

or 4 meters below the surface. This

community was composed of many

species typical of stagnant water.

No detailed description is given

here of the final “lake plankton”;

it may be said however, that at the

end of my observation period (Sep-

tember 1964) large colonies of

green algae, such as Dictyosphae-

rium, and many crustaceans and

rotifers seemed to be the more per-

manent components of the plank-

ton.

It is interesting to note, that

near the anaerobic zone of the lake

numerous specimens of the ro-

tifer Sinantherina spinosa appear-

ed and also numerous wiftly mov-

ing turbellarian worms ( Catenu ■

la lemnae). The above picture of

various plankton stages is based

on observations in open water. In

forest areas with drowned trees,

oxygen was limited to a thin top

layer and, as a result, the vertical

distribution of plankton was more

restricted. Also other organisms

typical of shallow stagnant water

were found. Since the trees acted

as a windscreen extensive fields of

Lemnaceae developed temporarily,

as well as large masses of float-

ing filamentous algae ( Spirogyra ,

Mougeotia) . The algae produced

large amounts of oxygen, often

leading to supersaturation, but

outside the algal mats oxygen was

absent. Many organisms were

found in the threads of algae, such

as bottom living Cladocerans ( Eu -

ryalona occidentalis, Iliccryptus,

Chydorus ) and many specimens of

the big Conchostracod Cyclesthe-

ria hislopi. These organisms occur-

red also in open water, transport-

ed by wind action. Also other or-

ganisms could be found in the al-

gal mats, such as ephemerids, odo-

nata, hemiptera, and locally the

gastropods Drepanotrema anati-

num, Aplexa marmorata, Gundla-

chia, Taphius khünianus and Acro-

loxus. They did not occur in the

former flowing water and must

have come from shallow, stagnant

parts. The dead leaves of the

drowned trees soon became covered

with green masses of filamentous

algae. When the water levei rose

these algae died by lack of light

but reappeared at a higher levei.

On the dead leaves also many tu-

bes could be found of oligochaetae

{Der o, Aulophorus, Pristina, Aeo-

Icsoma) .

Most of the organisms which liv-

ed on the former riverbed died on

136

Atas do Simpósio sôbre a Biota Amazônica

account of lack of oxygen at the

bottom. Some however were found

living at floating substrate such as

sponges, ephemerids and odonata.

Fish only cccurred as surface dwel-

lers in the oxygenated layer. The

bottom dwelling fish of the former

river died or escaped the anaero-

bic water. At Afobaka the first

dead fish were seen on 28 Februa-

ry. The number of dying fish, how-

ever, was only a small fraction of

the former population in the nor-

mal river. Most fishes probably

fled upstream and for this reason,

after the longer stagnation in Au-

gust and September, many fish

was seen in the upper courses of

the Suriname River.

The first fish found dead were

the stingray and a Plecostomus sp.

The latter lives in the turbulent

water of the rapids and soon after

stagnation this species could be

found floating dead on the water

above former rapids. The amount

of fish which remained in the oxy-

genated layer after stagnation was

not great. Catfish ( Siluridae , Cal -

lichthyidae) disappeared; species

such as Leporinus, Characidae and

a few Serrasalmus remained. Gym-

notus sp. was found living between

the roots of water-hyacinth.

The records of the organisms

present before and after the clo-

sure are given in a table at the

end of this communication.

The greatest depth of the lake

will be 50 meters near the dam.

Large areas of the shallower parts

will become swampy. Fishing with

nets and navigation will be diffi-

cult. The submerged trees of the

forest will decay very slowly in the

acid anaerobic water; it was impos-

sible to clear the area of the futu-

re lake before filling. The tree tops

remaining above water will serve

as centres of floating vegetation.

The waterhyacinth ( Eichhornia

crassipes) , which was scarce in the

river, developed into great num-

bers after stagnation because of

favourable conditions: the illumi-

nation of the water surface

increased as the dead leaves lost

their leaves and also the mineral

content of the water increased. The

control of this “million-dollar-

weed” was started by spraying, but

the result is not quite satisfactory.

Perhaps it is worth to make an ex-

periment of biological control by

introducig manatees into the lake

(Bertram, 1963) . The introduc-

tion of the manatee into the lake

would be, at the same time, a con-

tribution to the protection of this

threatened animal.

Finally we would point out the

possibility of explosions of mosqui-

tos and malaria on account of the

developing and expanding water-

hyacinth, and perhaps of the

waterfern Ceratopteris pterioides.

Volume 3 (Limnologia)

Presence of various organisms before and after the closure

1 February 1964 until September 1964

137

SURINAME RIVER

Fishes: Many species and specimens

Potamotrygon hystrix

Siluridae, Callichthyidae

Plecostomus sp.

Electrophorus electricus

Gymnotus sp. (in creeks)

Hoplias sp.

Serrasalmus sp.

Characidae

Belone sp. (in creeks) etc.

Other organisms:

Diatoms and Desmids are the most

important plankters.

Freshwater shrimps (Macrobrachium)

and crabs ( Potamocarcinus sp) are

common .

Hemiptera : Gerridae, Velidae and Be-

lostomidae are scarce.

Ephemeroptera on bottom and in

rapids.

Trichoptera on rocks and in rapids.

Libellulidae, many species.

Megaloptera and Cataclysta lived in

rapids.

Simulidae and other midge larvae

recorded.

Sponges on rocks.

Bryozoa recorded.

Moliusca: Pomacea spp. and Doryssa

spp. lived on rocks.

Diplodon voltzi and Castaliella lived on

sand.

Otigochaetae: earthworm species oc-

curred in the sand.

p °dostemaceae in rapids. Few Eichhor-

nia crassipes. Few Ceratopteris pte-

riodes.

Filaments of blue algae on rocks in

rapids.

BROKOPONDO LAKE

Few species and specimens. Dead fish

appeared shortly after stagnation.

Most fish escaped anaerobic water.

Some hide in floating water-hyacinth.

Surface dwellers like Leporinus re-

mained in the oxygenated layer at the

surface.

Other species of phytoplankton deve-

loped. Cladocera, Copepods and Roti-

fers appeared in great numbers, but

only in the oxygenated toplayers. New

elements typical of stagnant water

appear: Cladocerans : Euryalona occi-

dentalis, Iliocryptus; Conchostraca :

Cyclesteria hislopi; Rotifers: Sinanthe-

rina spp., Octotrocha, Lacinularia flos-

culosa. Bottom living organisms died

or appeared on floating substrate.

Many Microvelia sp'. Also Belostomidae

in floating material.

Only Asthenopus and Callibaetes were

recorded.

Trichoptera disappeared.

Libellulidae are still present. Both di

sappeared.

Larvae of Simulidae disappeared; other

forms were recorded. Spcnges disap-

peared except those cn floating subs-

trate.

Bryyozoa not recorded.

All species disappeared, some were

found dead. New elements typical of

stagnant water are recorded:

Drepanotrema anatinum, Aplexa mar-

morata, Gundlachia, Acroloxus, Ta-

phius.

Not recorded. Many small species like

Dero, Aulophorus and Pristina appear

on decaying substrate.

No Podostemaceae.

Strong development of Eichhornia and

Ceratopteris.

Filaments of blue algae on roots of

waterhyacinth and floating substrate.

Temporary growth of filamentous

green algae ( Spirogyra , Mougeotia )

floating at the surface. Growth of

Lemnaceae.

SciELO

10 11 12 13 14 15

cm

138

Atas do Simpósio sôbre a Biota Amazônica

SUMMARY

The construction of big dam

across the Suriname River, which

was completed at February 1, 1964,

caused a radical change of the en-

vironment in which so far a tropi-

cal rainforest dominated .The im-

pounded Suriname River soon

flooded large areas of forest: the

artificial lake will ultimately cover

an area of about 1.500 km-. About

5.000 inhabitants of negro villages

along the river were transmigrated

to new settlements. Wild animais

such as deer, pig, opcssum, baboon,

tree porcupine, tree anteater and

sloth tried to escape the rising wa-

ter. Many of them were rescued by

the action of the American Socie-

ty for the Protection of Animais.

Game hunting is forbidden for

some years in the lake region.

The drowned forest trees died

after a few months but their stems

remained below the water levei, so-

me parts also above it. No attempts

could be made to clear the future

lake region before actual filling oc-

curred. The dead trees are a nui-

sance for navigation and fishing

with nets. They also prevent water

circulation, resulting in great stag-

nation and oxygen exhaustion.

Open spaces of water remain only

in the former riverbed and in those

of the tributaries. As the water

of the lake will be used only for ge-

nerating electric power little atten-

tion is being paid to the said draw-

backs.

The waterhyacinth Eichhornia

crassipes was a rare plant in the

former Suriname River but deve-

loped rapidly as soon as the water

stagnated. Large fields of floating

plants formed along the borders.

Attempts were made to control it

by Chemical sprays, without much

result. At the midst of 1965 the

plant covered an area of 18000 ha.

which is about 1/8 of the total area

of the lake. Also the waterfern Ce-

ratopteris thalictroides spreads ra-

pidly; it used to be limited to the

smaller tributaries of the Surina-

me River.

As the lake will remain shallow

for the greater part (the greatest

depth does not exceed 50 meters,

near the dam) , large areas will be

covered by a swampy vegetation.

This vegetation will cause an in-

crease of the evaporation, which

will be much higher than that of

open water. (The rate of evapora-

tion of open water in the lake has

only been measured incidentally) .

The lake did nct reach its final le-

vei at the expected date. In fact

the water levei lowered slightly

when two of the turbines were

started.

Volume 3 (Limnologia)

139

An invertebrate fauna — for-

merly scarcely noticed — develop-

ped in the stagnant water among

the floating vegetation of water-

hyacinth. It may be that inalaria

mosquitos will become numerous

after prolonged impoundment.

Snails, a potential vector in bilhar-

zia disease, were not recorded; as

a matter of fact they were absent

in the Suriname River because of

the acidity of the water and the

absence of a suitable environment.

Other species of snails occurred

however .

After stagnation of the water

occurred, the river fish of the run-

ning water disappeared. Exhaus-

tion of oxygen caused some dying

of fish. Oxygen started decreasing

some weeks after the stagnation

and then only few specimen were

found at the surface. Below a

depth of 2 to 3 meters no oxygen

was found. H..S developed by de-

caying of organic material.

The plankton community of the

running river was mainly compos-

ed of desmids and diatoms. It soon

changed and became limited to an

upper layer of 2-3 meters. Cladoce-

ra, Copepoda, Rotifer and unicel-

lular Flagellates (Strombomonas,

Trachelomonas) developed, some-

times in large numbers. Bottom or-

ganisms of the former riverbed

died or were found living on float-

ing material. Plant species belong-

ing to the family of Podostema-

ceae, typical of the rapids, died

also.

The Chemical composition of the

water changed too. The water of

the Suriname River was poor in

minerais, slightly coloured by iron

and silica and had a pH of about

6.5. It resembles the “Clear water

type” as characterized by Sioli in

the Amazon. The tributaries are

brownish and turbid cn account

of iron. The Suriname River Sys-

tem originally has turbid-brown

water and differs from the so-

called “Brown waters”, where co-

lour is due to dissolved humic sub-

stances.

After impoundment the water

colcur changed into light brown,

due to dissolved humic substances,

the pH dropped to about 5.5. The

mineral content increased. The

amounts of mg pro liter of P0 4

NO;: and S0 4 increased already

after 6 months of stagnation.

Very little was known of the wa-

ter, plants and animais in the Su-

riname River region. Some months

before the closure of the dam a

team of four biologists began its

investigations. The project is being

financed by the Netherlands Foun-

140

Atas do Simpósio sôbre a Biota Amazônica

dation for the Advancement of

Tropical Research (Wotro) and

the National Museum of Natural

History, Leyden.

REFERENCES

Bertram, C., 1963, In search of Mer-

maids. 183 pp„ Peter Davies, Lon-

don.

Braun, R., 1952, Limnologische Unter-

suchungen an einigen Seen im

Amazonasgebiet. Schweiz. Zeits.

Hydrol., 14 (1) :

Leentvaar, P., 1966, The Brokopondo

Research Project, Surinam, In:

Symposium on Man-Made Lakes,

London.

Sioli, H., 1964, General features of the

limnology of Amazônia. Verh.

Intern. Ver. Limnol., 15:

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 141-162 — 1967

EL GÉNERO “PALEOSUCHUS” EN AMAZÔNIA

FEDERICO MEDEM

Departamento de Investigaciones Ictiológicas y Faunísticas; Corporación

Autónoma Regional de los Valles dei Magdalena y dei Sinú (C.V.M.) ;

Cartagena (Bolívar) , Colombia

(Con 1 mapa)

El género Paleosuchus consiste

en dos especies, P. trigonatus y

P. palpebrosus. Representa indu-

dablemente un grupo muy anti-

guo, quizás, el más primitivo de la

familia Alligatcridae y difiere de

los géneros Caiman y Melanosu-

chus por una serie de caracteres

morfológicos externos y anatómi-

cos craneales. Se desconocen toda-

via datos paleontológicos exactos

sobre el orígen de este género.

Langston (1965: 151) anotó que

“La ascendência dei caimán se ras-

trea hasta el principio dei Eoceno,

en cuya época el Eocaiman caver-

nensis parece haber sido un ade-

cuado antecesor estructural de

formas semejantes al caimán, con

la posible excepción dei Paleosu-

chus”.

El autor de la presente contribu-

ción hizo observaciones y estúdios

desde 1950 en las hoyas dei Ama-

zonas y Orinoco, coleccionando

principalmente de noche con ar-

pón y desde una canoa para evi-

tar la destrucción dei cráneo, si se

recolectaran mediante armas de

fuego. Durante estas cacerías se hi-

cieron numerosas observaciones so-

bre la ecologia y las costumbres en

el ambiente natural de ambos Pa-

leosuchus, comunmente denomina-

dos como “Cachirre” y “Jacaré co-

roa” por los nativos de las diferen-

tes regiones.

Los datos aqui presentados no

pretenden ser completos; consti-

tuyen más bién base para estúdios

futuros más profundos. A pesar de

que ambas especies se conocen

desde la época de Cuvier (1807),

existen solamente unos pocos datos

aislados y generalizados sobre su

ecologia. La nomenclatura también

permaneció en estado bastante

confuso debido a las numerosas al-

teraciones que ha sufrido la sino-

nimia.

142

Atas do Simpósio sôbre a Biota Amazônica

Debido al espacio limitado, pre-

sentamos únicamente la sinonimia

principal, evitando así meras rei-

teraciones, y nos referimos para

una nomenclatura más completa a

Medem (1958 a: 228-230). Igual-

mente nos limitamos a presentar

los datos más esenciales acerca de

las características morfológicas ex-

ternas y de anatomia craneal, ya

que han sido descritos anterior-

mente por vários autores, entre

ellos Kàlin (1933), Mertens ....

(1943) y Medem (1952, 1953

1958 a). En cambio, nos referimos

en forma más detallada a las obser-

vaciones sobre la ecologia y com-

portamiento por razón de que re-

presenten posiblemente informa-

ciones útiles para otros profesio-

nales en su trabajo en el campo.

Se usan las siguientes abrevia-

ciones: cnhm — Chicago Natural

History Museum; mvz — Museum

of Vertebrate Zoology, University

of Califórnia, Berkeley; mnhnp

— Museum National d’histoire Na-

tural de Paris; icn — Instituto de

Ciências Naturales, Universidad

Nacional de Colombia, Bogotá; fm,

Pp, Pt — Federico Medem, colec-

ción particular, P. trigonatus y

P. palpebrosus. El material está de-

positado en el cnhm, mvz, icn y

en la colección particular.

Nomenclatura

Orden Crocodylia

Familia Alligatoridae

Género Paleosuchus Gray, 1862,

Ann. Mag. Nat. Hist., (3), 10:

330; propuesto como subgénero

de Caiman. Tipo: Crocodilus tri-

gonatus Schneider.

Paleosuchus trigonatus

(Schneider)

Crocodilus trigonatus Schneider, 1801,

Hist. Amph., p. 161, pis. 1-2. Tipo:

actualmente perdido. Localidad

típica: desconocida.

Caiman trigonatus Boulenger, 1889, Ca-

tai. Chelon. . . : 296.

Jacaretinga trigonatus Vaillant, 1898,

Nouv. Arch. Mus. Hist. Nat. Paris,

(3), 10: 171 etc., fig. 1.

Paleosuchus trigonatus K. P. Schmidt,

1928, Field Mus. Nat. Hist. (Zool.

Ser.), 12: 209, fig. 1.

Crocodilus palpebrosus, var. 2, Cuvier,

1807, Ann. Mus. Hist. Nat. Paris,

10: 38 pl. 2, fig. 1.

Tipo: mnhnp No. 7.525, ejemplar de

80 cm., Gautier don. Localidade

típica: Cayenne — /ide Vaillant,

1898: 174, fig. 1.

Alligator palpebrosus, var. B, Dumé-

ril & Bibron, 1836, Erp. Gén., 3.: 72.

Tipo: mnhnp No. 7527, ejemplar de

1.17 metros, localidad desconocida

fide Vaillant ( op . et loc. cif.).

Jacaretinga moschifer Spix, 1825, Ani-

malia nova... lacertarum, p.l Tab.

I. Tipo: Originalmente en München,

actualmente perdido.

Localidad típica: lago en la ciudad

Bahia, Brasil.

Vaillant (op. cit.: 173-174, nota

al pié) anotó que moschifer es una

composición de ambas especies. Se-

gún la descripción se trata de pal-

pebrosus, mientras la ilustración

Volume 3 (Limnologia)

143

muestre indubablemente un trigo-

natus de tamano mediano. Seria lo

más indicado, incluir a moschifer

definitivamente en la sinonimia de

trigonatus ya que no solamente la

Tabla I de Spix comprende una

ilustración en colores bien elabo-

rada de trigonatus, sino también

en el texto se notan algunas dis-

crepâncias: mientras la descrip-

ción dei color corresponde a pal-

pebrosus, la de la cabeza reza “ca-

put acutum” (p.l), lo que es carac-

terístico de trigonatus.

Paleosuchus palpebrosus

(Cuvier)

Crocodüus palpebrosus, var. 1, Cuvier,

1807, Ann. Mus. Hist. Nat. Paris,

10: 28; pi. 1, figs, 6, 17; pl. 2, fig. 2.

Tipo: mnhnp No. 7530, ejemplar de

1.29 metros, Gautier don, Localidad

tipica: Cayenne, fide Vaillant (op. et.

loc. cit.) .

Alligator palpebrosus, var. A. Duméril

& Bibron, Erp. Gén., 3: 67. Tipo:

mnhnp No. 7530, Jide Vaillant (op. et

loc. cit).

Caiman (Aromosuchus) palpebrosus

Gray, 1862, Ann. Mag. Nat. Hist., (3) ,

10: 330.

Paleosuchus palpebrosus Müller, 1924,

Zeitschr. Morph. Okol. Tiere, 2: 441,

pl. 5, fig. 31.

Champsa gibbiceps Natterer, 1841, Ann.

Wien. Mus., 2: 324, pl. 28. Tipo: Ori-

ginalmente en Viena, evidentemente

perdido.

Localidad típica: Ribeirão do Gua-

curizal, um cano en las montanas al-

rededor de Jacobina, 3 millas al ori-

ente de Villa Maria, rio Paraguai,

Mato Grosso, Brasil.

Coloración — El color de los

ejemplares vivos ya ha sido descrito

anteriormente (Medem, 1952

1953) ; por esta razón anotamos

solamente las diferencias principa-

les correspondientes a los adultos

y juveniles.

En P. trigonatus la tabla craneal

es parda oscura y una faja ancha

negra se extiende desde el borde

posterior de espacio interorbital ha-

cia adelante a lo largo de los na-

sales hasta los clientes maxilares

Nos. 5-6. En cambio, en P. palpe-

brosus la tabla craneal es de color

rojizo de herrumbre intenso y ia

cabeza carece de la faja negra.

Las mandibulas presentan zonas

anchas amarillas, interrumpidas

por unas 5-6 fajas transversales

pardas oscuras en trigonatus, mi-

entras las de palpebrosus muestran

un color rojizo, salpicado por unas

4-5 manchas pardas oscuras de ta-

maho y configuración irregulares.

La parte dorsal dei cuerpo y de

la cola de trigonatus es básicamen-

te parda oscura; existe, sinembar-

go, el fenómeno en que virtualmen-

te todos los juveniles desde unos

600 mm para arriba y los adultos

tienen el lado dorsal cubierto por

una densa capa de algas verdes la

cual es aún más espesa en ejem-

plares viejos; por esta razón un

trigonatus de tamano mayor pa-

rece, en realidad, verduzco mohoso.

El lado dorsal de palpebrosus es

más oscuro y en ejemplares viejos

144

Atas do Simpósio sôbre a Biota Amazônica

negruzco. Nunca se ha observado

la presencia de algas verdes en

palpebrosus en su ambiente natu-

ral, sino únicamente en un solo

ejemplar (No. 370), que vivió dos

anos en cautividad.

Ventralmente el color dei tegu-

mento es gris ratón con varias zo-

nas más oscuras en trigonatus, mi-

entras en palpebrosus es negro bri-

llante con algunas zonas grises

claras o de color de cuerno.

Los juveniles de ambas especies

tienen una coloración más clara y

intensa que los adultos. Ejempla-

res muy pequenos se distinguen

facilmente en que la tabla craneal

en los de trigonatus es carmelita

clara, mientras en los palpebrosus

es amarilla yema brillante. Este

color cambia después de unos ocho

meses; así por ejemplo, de tres

ejemplares capturados en diciem-

bre 1, 1950, uno (MVZ No. 2018) de

ellos sobrevivió hasta septiembre 5,

1951; según Hendrickson ( in litt.,

octubre 11, 1951) el color perman v

ció amarillo hasta julio 1951 y lue-

go cambio a rojizo caoba (Medem,

1953: 417). El iris de los ojos de

ambas especies es carmelito claro.

Escamado — Desde la época de

Cuvier (1807) se considero la

cisposición de las escamas postoc-

cipitales como uno de los factores

diagnósticos específicos, es decir, se

postulo que trigonatus invariable-

mente tenía una sola hilera y, en

contraste, palpebrosus dos de ellas.

En realidad, 28 de los 37 ejempla-

res de trigonatus estudiados en

1954, tenian las escamas postocci-

pitales en dos hileras claramente

discernibles, independientes de la

edad y procedência; en cambio, de

unos 50 palpebrosus, todos poseían

dos hileras.

Existen también diferencias cla-

ramente discernibles entre ambas

especies respecto al escamado cer-

vical, dorsal, ventral y caudal

(Medem, 1958 a: 236). Finalmen-

te, nos referimos a las diferencias

más esenciales y fácilmente discer-

nibles tanto dei escamado como de

la anatomia craneal de ambas es-

pecies que sirven como factores

diagnósticos para su clasificación.

ESCAMADO

Paleosuchus trigonatus

1) Escamas postoccipitales en una

o dos hileras; las de la segunda

siempre más pequenas.

2) Hileras pre-lumbares de 2-3-4

placas; las centrales o lisas o

con cresta vestigial; existe gran

variedad individual.

3) Hileras lumbares igualmente de

2-3-4 placas; las centrales o li-

sas o con cresta vestigial.

Paleosuchus palpebrosus

1) Escamas postoccipitales siem-

pre en dos hileras; las de la se-

gunda ligeramente más peque-

nas; solamente en los s £ vie-

jos de tamano igual.

77i°

76 1 c

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74 ®

73 °

72 *

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67 1

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10 11 12 13 14 15 iSClELOg 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

Volume 3 (Limnologia)

145

2) Hileras pre-lumbares casi siem-

pre de 4 placas encrestadas; po-

ças excepciones en ejemplares

juvenil es.

3) Hileras lumbares usualmente de

4 placas aquilladas; pocas ex-

cepciones en juveniles.

CRÁNEO

Paleosuchus trigonatus

1) Hocico alargado; punta angos-

ta; no volteada hacia arriba.

2) Proyección anterior de los na-

sales larga y puntiaguda.

3) Canthus rostralis falta; lacri-

males prominentes y muy ele-

vados.

4) Declive lateral de los maxilares

no pronunciado.

5) Foramen mandíbulare exter-

num grande y ancho; los bor-

des son siempre lisos.

6) Fenestrae supratemporales abi-

ertas en juveniles, cerradas en

adultos, pero usualmente con

una brecha bien discernible.

Paleosuchus palpebrosus

1) Hocico comprimido; punta an-

cha y volteada hacia arriba.

2) Proyección anterior de los na-

sales corta y ancha.

3) Canthus rostralis prominente

entre los lacrimales y los dien-

tes maxilares Nos. 4.

4) Declive lateral de los maxilares

muy pronunciado.

5) Foramen mandibulares exter-

num pequeno y angosto; los

bordes son siempre mellados o

dentados.

6) Fenestrae supratemporales to-

talmente obliteradas en adultos

y juveniles.

Medem & Marx (1955: 1) sena-

laron la presencia de las Fenestrae

supratemporales muy pequenas en

juveniles de ambas especies; esto

fue un error y no corresponde a los

P. palpebrosus.

Tamano — Como en todos los

Crocodylia, los s 6 alcanzam un

tamano mayor que las 9 9 . En tri-

gonatus las longitudes mayores co-

nocidas hasta la fecha son de 2256

mm para los s $ (cnhm No.

81980) y 1330 mm para las 9 9

(Pt. 15) .

El tamano mayor sehalado en

la literatura para palpebrosus es

1720 mm (Luederwaldt, 1926) ;

hasta la fecha no se ha colecciona-

do un ejemplar de sem ej antes di-

mensiones en Colombia; el mayor

tamano comprende 1545 mm para

los $ ê (cnhm No. 69871) y

1230 mm para las 9 9 (cnhm

No. 69868). Datos sobre la madu-

rez sexual en relación con el tama-

ho no existen, pero un palpebro-

sus, $ , (Pp 3) de 854 mm era ya

adulto, según el estado de desar-

rollo dei pene y testículos.

Ecologia y comportamiento —

En lo concerniente a la ecologia

10 — 37 121

146

Atas do Simpósio sôbre a Biota Amazônica

y las costumbres nuestro conoci-

miento es todavia insuficiente. Con

toda la razón Schmidt (1928: 210) ;

Leitão de Carvalho (1951: 134-

-135) y Dunn (1945: 333) ya han

expresado que virtualmente no se

sabe nada al respecto.

Natterer (1841: 318) senaló por

primera vez la localidad exacta y

el habitat para P. trigonatus como:

“Rio Negro, alrededor dei Cerro

Cocuí, en canos y lagos dentro la

selva”; menciono, además, que

P. palpebrosus se encuentra en el

Rio Branco, donde se excavó un

ejemplar de una cueva de una bra-

za (1.67 metros) de profundidad,

situada en un pantano seco de una

llanura.

Müller (1912: 39; 1924: 455)

encontro ambas especies juntas en

la Isla Mexiana y apuntó que vi-

ven en los igarapés dentro la sel-

va y se retiran a las cuevas situa-

das en la orilla de las aguas du-

rante el dia.

Habitat y nicho ecológico — Am-

bos Paleosuchus son coexisten-

tes con Caiman sclerops y Melano-

suchns niger pero se encuentran

en un ambiente preferido diferen-

te y bien definido el cual se puede

denominar como: aguas corrento-

sas dentro la selva tropical. Así por

ejemplo, en el rio Pacoa los Paleo-

suchus se encontraron con certeza

siempre en tales partes donde el

agua corria sobre un fondo rocoso,

alrededor de chorreras, cachoeiras,

saltos y remolinos, mientras los

Caiman sclerops apaporiensis vi-

vían en las vueltas y grandes char-

cos donde las aguas eran mansas

y algo estancadas.

En las lagunas Inaná, P. palpe-

brosus se encontro solamente en el

cario que conecta la segunda y ter-

cera laguna y a unos 50 metros de

distancia de su desembocadura en

la segunda laguna (Medem, 1953,

mapa 2).

En los rios grandes ambas espe-

cies se encuentran siempre alrede-

dor de raudales, angosturas, remo-

linos y chorreras.

En regiones donde no existe la

selva tropical propiamente dicha,

como por ejemplo, en las mesetas

semi-áridas dei Vaupés entre los

rios Querarí y Guaracú, y en los

Llanos Orientales, los Paleosuchus

están presentes en los pequenos

afluentes, pero únicamente en ta-

les partes donde la orilla está

cubierta por un monte espeso; en

cambio, evitan las partes dei mis-

mo cano donde consiste en llanu-

ras. Esto no quiere decir, sinembar-

go, que los Paleosuchus nunca en-

tren a aguas estancadas, sino úni-

camente que nunca han sido obser-

vados en tal nicho ecológico, con

la sola excepción de un P. trigona-

tus (Pt 29) en las aguas mansas de

un monte inundado por el invierno.

Abundância — Ambos Paleosu-

chus son mucho menos abundan-

tes que, por ejemplo, C. sclerops y.

cm l

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10 11 12 13 14 15

Volume 3 (Limnologia)

147

en tiempos pasados, M. niger; son,

sinembargo, no tan escasos como

siempre se ha pensado.

Así por ejemplo, en el Alto Iní-

rida y su afluente el Cano Grande

se observaron durante el día de

Enero 23 a febrero 9, 1957, 18 tri-

gonatus, 2 palpebrosus y 102

C. sclerops; en agosto 8, 1957 en el

cano Icapuyá 6 trigonatus y un

solo palpebrosus de las 7:00 —

11:00 p.m. y en noviembre 19, 1958

de las 9:00 — 11:00 p.m. 5 trigona-

tus y 10 sclerops. El senor Carlos

Alberto Velásquez observo en di-

ciembre 1958 en el cano Pachaquia-

ríto (Meta) tíe noche en un área

de unos 130 metros aproximada-

mente 16 palpebrosus, entre ellos

2 grandes.

Alimentación — Es muy variada

y no se observo un grupo de ani-

males como alimento preferido.

Los juveniles se alimentan princi-

palmente de moluscos, crustáceos

e insectos acuá ticos y terrestres

( Pomacea sp; camarones, cangre-

jos, Coleoptera, Orthoptera, Odo-

nata); en los adultos se encuen-

tran también invertebrados con

frecuencia; además peces hasta

unos 300 milímetros; ranas ( Lep -

todactylidae, Hylidae) ; serpientes;

escamas de C. sclerops; unas de

ejemplares juveniles y adultos de

Caiman o Paleosuchus; plumas de

diferentes aves pequenas; unas

de garzas ( Ardeidae ); mamíferos

( Marsupialia , Rodentia). El conte-

nido de un palpebrosus de 854 mm

(Pp 3) consistió en 3 larvas de mos-

cas (Diptera) , una arana acuática

(Arachnidae) , 3 cangrejos ( Crus-

tácea ), un camarón ( Crustacea )

y desperdicios de nuestra comida

botada al cano (costillas y carnes

de un Tayassú, pedazos de bana-

nas) .

En casi todos los ejemplares

adultos y juveniles de ambas espe-

cies se encontraron una cantidad

considerable de pedrezuelas (gui-

jarros) hasta un diâmetro de 2 a 4

centímetros. Así por ejemplo, un

trigonatus de 2256 mm (cnhm

No. 81890) tenía 94, un palpebro-

sus de 1530 mm (cnhm No. 69867)

69 guijarros. Solamente un peque-

no trigonatus (380 mm; cnhm

No. 69888) no tuvo ningún objeto

sólido en su estômago; en cambio

en un palpebrosus de 257 mm

(mvz No. 2016) se encontraron

unos 32 diminutas pedrezuelas, se-

gún las fotografias tomadas con

rayos X de ambos ejemplares. La

cantidad de guijarros evidentemen-

te no aumenta con el tamaho in-

dividual en todos los ejemplares,

ya que vários grandes capturados

en aguas de fondo rocoso tenían

solamente entre 2 y 5 pedrezuelas

en el estômago, mientras otros dei

mismo sitio las tenían en cantida-

des; quizás, las eliminan por via

natural; en el colon nunca se en-

ccntraron guijarros sino única-

mente barro.

cm 1

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148

Atas do Simpósio sôbre a Biota Amazônica

Como ectoparásitos se encontra-

ron sanguijuelas ( Hirudinae ) en

la boca y entre las escamas latera-

les de trigonatus; además se obser-

vo en todos los ejemplares de esta

especie un tábano ( Diptera , Taba-

nidae ) que succiona principalmen-

te la zona negra entre el espacio

interorbital y la punta dei hocico

la cual es blanda y muy irrigada

por la sangre (Medem, 1958 b:

fig. 10) ; nunca se observo este tá-

bano en palpebrosus el cual carece

de esta zona.

Un solo trigonatus y 4 palpebro-

sus tenían como endoparásitos em

tre uno y tres nemátodos en los es-

tômagos; se encontro un tremátodo

en el Ductus nasalis de un palpe-

brosus; úlceras estomacales se ob-

servaron en un solo ejemplar de

cada especie, posiblemente causa-

das por las espinas de peces.

Reproducción — Hemos encon-

trado un solo dato al respecto en

la literatura, Bates (1864: 119-120)

apunto: “Jacaré curua; female; not

more than 2 feet long; according

to the Indians it was full grown.

Captured near its nest containing

eggs. Eggs larger than a hen’s, re-

gularly oval. Nest near water edge.

The Jacaré curua lives only in

shallow creeks. Never seen again.”

Faltan los datos exactos sobre la

especie, localidad y fecha, pero se-

gún el diário ésta comprende en-

tre septiembre 27-30. Igualmente

no hemos encontrado huevos de

ambos Paleosuchus en todas las co-

lecciones estudiadas hasta la fecha.

Ni Goeldi (1898) ni Hagmann

(1902; 1906-1907; 1909-1910) que

hicieron tantas contribuciones al

conocimiento sobre la ecologia de

los Alligatcridae dei Amazonas, su-

ministraron datos respecto a los

Paleosuchus. Faltan todas las ob-

servaciones personales respecto a la

anidación, etc.; solamente hemos

observado en enero 5, 1957 en el

rio Gafre una 9 de trigonatus

(1330 mm; Pt. 15) perseguida por

dos <5 ô (1602 mm, Pt 14), todos

evidentemente en ceio y tan ocupa-

dos que se logró capturar a uno

de los á y la ç ; los ovários bien

desarrollados no contenían óvulos.

Además, presentamos algunos da-

tos obtenidos por los indios y cau-

cheros, personas que conocen bien

a ambos Paleosuchus:

1) El sehor Alirio Mejía encontro

entre octubre 20-23, 1956, cer-

ca dei campamento “El True-

no” a cinco horas arriba dei

Pirá-Paraná, en el rio Apaporis

un nido de palpebrosus cerca de

la orilla de un cano; contenía

unos 22 huevos de cáscara blan-

ca, lo que indica que eran re-

cién puestos; eran de tamaho

de los de C. sclerops aproxima-

damente pero su diâmetro era

algo menor. La 9 no defendió

el nido sino escapo al agua.

cm 1

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10 11 12 13 14 15

Volume 3 (Limnologia)

149

2) El indígena Perimaté de la tri-

bú de los Tanimúca, oriundo de

la misma región y companero

en las cacerías nocturnas, ase-

guró que ambos “Jacaré coroa”

nunca ponen en el verano (di-

ciembre-marzo) sino entre agos-

to y noviembre; los huevos son

tan grandes como los dei “Ja-

caré tinga” pero más alargados

y delgados, algo como de las

culebras; los nidos son hechos

de hojarasca amontonada; la 2

acumula las hojas con la cabe-

za y la cola y luego hace el

cúmulo con movimientos late-

rales de la cola.

3) En la región dei rio Guayabe-

ro-Guaviare ponen en febrero-

marzo y la cria sale en abril-

mayo. Posible se trata de trigo-

natus, la especie predominante

entre San José dei Guaviare y

la Angostura No. 2.

4) El senor Castro Losada encon-

tro a mediados de diciembre de

1949 un nido de un “Cachirre

negro” (evidentemente palpe-

brosus) en un cano cerca dei

rio Guatiquía, región de Villa-

vicencio, de un metro de altura

por 80 centímetros de ancho

aproximadamente el cual con-

tenía unos 18 huevos; la 2 no

escapo sino atacó furiosamente

hasta que la mataron.

Enemigos — Los Paleosuchus de

tarnano mayor devoran ocasional-

mente a los más pequenos; el “Güio

negro” ( Eunectes murinus gigas )

muy posiblemente se alimenta tam-

bién de ellos, ya que se han encon-

trado repetidas veces ejemplares de

C. sclerops hasta unos 2050 milí-

metros en los estômagos de estas

serpientes. Tanto el “Jacaré assú”

(M. niger) como el “Tigre” ( Felis

onca ) y el “Tigrillo” ( Felis ozelot )

son otros enemigos potenciales; he-

mos observado el último capturan-

do y luego comiendo C. sclerops de

unos 600 milímetros e Iguanas. Si-

nembargo, el enemigo principal es

indudablemente el indígena; los

indios distinguen dos formas dei

“Jacaré coroa” y las prefieren por

su carne superior a la dei “Jacaré

tinga” (C. sclerops) ; consecuente-

mente, en regiones habitadas por

indígenas los Paleosuchus son es-

casos y muy ariscos. A pesar de que

hemos usado con frecuencia como

alimento a los adultos de ambos

géneros, no hemos encontrado nin-

guna diferencia acerca dei sabor.

Hábitos y costumbres — Son

principalmente nocturnos; salen

entre las 7:00 — 7:30 p.m. y cazan

generalmente hasta las 10:30 p.m.;

en los grandes rios se encuentran

generalmente escondidos dentro

las palizadas; en aguas profundas

su posición es algo diferente de la

de C. sclerops; mientras el cuerpo

dei último se queda por lo general

a poca profundidad bajo la super-

fície y es visible, en los Paleosuchus

150

Atas do Simpósio sôbre a Biota Amazônica

se encuentra “colgado” casi verti-

calmente hacia el fondo, no es vi-

sible y bastante difícil para apun-

tar con el arpón. En regiones don-

de nadie los molesta salen también

de dia para asolearse; los trigona-

tus permanecen con frecuencia

bajo rastrojo al borde de las aguas

y evitan las orillas que carecen de

vegetación; los palpebrosus se aso-

lean en general en aguas poco pro-

fundas o en las rocas y árboles

gruesos dentro de las chorreras con

la cabeza pronunciadamente er-

guida. Sorprendidos en lo seco y es-

pecialmente en las orillas elevadas,

saltan con gran rapidez al agua y

no corren en cuatro patas, como lo

hacen C. sclerops; repetidas veces

saltaron así sobre la canoa y desa-

parecieron en el agua a una distan-

cia de unos 2-3 metros. Viven en

cuevas en las orillas bajo la super-

fície dei agua; ejemplares recién

salidos mostraron muchas veces

rastros de barro en sus cabezas;

cuando el nivel de las aguas se baja

durante el verano, se observaron

las entradas de estas cuevas cuya

profundidad varia entre 1.50 —

2 . 50 metros aproximadamente.

En relación con su nicho ecoló-

gico de aguas correntosas sus mo-

vimientos son muy ágiles; nadan

con gran velocidad aún contra la

corriente fuerte y cambian rápida-

mente la dirección. Su modo de

cazar peces es muy efectivo; en tres

ejemplares amarrados en un cano

con un guaral de unos diez metros

de largo se observo durante tres se-

manas que el adulto permaneció

inmóvil hasta que una manada de

peces se acerco a cierta distancia

y luego súbitamente formó casi un

círculo mediante los movimientos

de la cola y la cabeza, empujando

así los peces hacia la boca, nunca

falló; en cambio, los dos juveniles

raras veces cogieron algo.

Nunca se encontro a ambas espe-

cies en agrupaciones, como es co-

mún en C. sclerops, sino casi siem-

pre solitárias. Por lo general, en los

canos se ve un solo Paleosuchus

durante cada hora; los adultos

ocupan aparentemente un nicho

individual extenso y lo defienden

contra otros indivíduos invasores.

Cada vez cuando un ejemplar ha-

bía sido capturado y el nicho se

quedó vacío, en pocos dias otro

ocupó este terreno. Aún los juve-

niles recién nacidos se separan evi-

dentemente pronto y nunca se ob-

servo una nidada entera en el

agua; al contrario, los palpebrosus

(mvz 2016; FM Nos. 763-766) fue-

ron capturados en las partes de

aguas movidas de pequenos ria-

chuelos, donde permanecieron con

la cabeza erguida contra la corrien-

te, y nunca se observaron más de

dos juntos. La coloración tiene in-

dudablemente un valor selectivo en

el sentido de que por una parte pro-

teje al indivíduo en su ambiente

natural contra sus enemigos y por

cm l

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10 11 12 13 14 15

Volume 3 (Limnologia)

151

otra facilita capturar animales

para su alimento. Así por ejemplo,

en trigonatus la zona negra a lo

largo dei hocico “disuelve” la for-

ma de la cabeza totalmente; y jun-

to con la capa espesa de algas en el

cuerpo hace que un ejemplar que

permanece inmóvil en el fondo de

las aguas poco profundas sea vir-

tualmente invisible aún a distan-

cia corta; ejemplares adultos se

parecen a un tronco podrido y úni-

camente la cresta caudal sencilla,

debido a sus escamas aserradas y

sobresalientes, indica su presencia.

El efecto “disruptivo” es aún más

conspícuo en los palpegrosus; el

contraste entre el color de herrum-

bre de la cabeza, aún más intenso

en el agua, y el negro dei cuerpo

es tan pronunciado que un indiví-

duo adulto en un cano sobre un

fondo de hojas podridas y de pie-

dras de multíples colores desapare-

ce por completo. Andando en pe-

quenos canos de unos 50 centíme-

tros de profundidad contra la cor-

riente para mejor visibilidad, he-

mos pasado ejemplares grandes a

un metro de distancia sin darnos

cuenta de su presencia hasta que

súbitamente se movieron con gran

velocidad; trataron casi siempre de

escapar; solamente en un caso el

animal nos atacó.

Kalin (op. cit .: 705) opinó que

las especializaciones morfológicas

en los Paleosuchus indiquen una

tendência hacia la vida terrestre;

evidentemente no los conoció en su

habitat. Nunca hemos observado

que en su ambiente natural am-

bas especies muestren una pronun-

ciada preferencia por alejarse

de las aguas. Al contrario, son apa-

rentemente más acuáticos que

C. sclerops; aún en cautividad per-

manecieron más en un tanque que

sclerops, pero lo abandonaron en-

seguida cuando el agua estancada

se volvió sucia y verde. Se mueven,

sinembargo, con gran velocidad en

tierra a cortas distancias; igual-

mente, andan ã veces muy lenta-

mente en las cuatro patas levan-

tadas y sin arrastrar el cuerpo, se-

mejando los movimientos de un

gato cuando se acerca a una pre-

sa; posiblemente cogen de esta ma-

nera animales en tierra. Nunca he-

mos observado un caso de estiva-

ción en ambas especies, como lo

menciono Natterer (op. et loc.

cit.) para palpebrosus. Un palpe -

brosus (fm No. 370) mostro una

resistência extraordinária a las

temperaturas bajas a gran altura:

Traído a Bogotá (2.650 metros)

permaneció primero en el Instituto

de Ciências Naturales sin calefac-

ción artificial; escapo y fue encon-

trado después de nueve dias en el

pasto al lado de un pozo cerca dei

laboratcrio, completamente sano,

agresivo y bien alimentado; eviden-

temente comió durante esta época

ranas (Hyla labialis) abundantes

en este sitio; la temperatura bajó

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152

Atas do Simpósio sôbre a Biota Amazônica

de noche a 6°C. y un C. sclerops

adulto murió en tres dias. Luego

vivió en mi casa en un tanque con

calefacción por más de un ano,

pero muchas veces salió y perma-

neció escondido por dias en el seco,

donde la temperatura fluctuaba

entre 19° — 13°C.; finalmente vi-

vió otro ano en un clima tropical

donde murió por accidente, entran-

do a un tanque de agua marina.

Distribución geográfica — Indu-

dablemente el centro de la distri-

bución está situado en el sistema

hidrográfico dei Amazonas, toma-

do en un sentido amplio, e inclu-

yendo el Orinoco el cual está

en conección con el Amazonas pro-

piamente dicho por el brazo Casi-

quiare dei rio Negro. Aparente-

mente la evolución dei género Pa-

leosuchus tuvo lugar a princípios

dei Terciário en esta área, un ha-

bitat que virtualmente no ha cam-

biado, sino todavia persiste; su mi-

gración y presencia actual en otras

regiones extensas está en estrecha

relación con su adaptación a un

nicho ecológico definido. Muy po-

siblemente, hoy en dia falta en

muchas áreas donde antes existia,

debido a la alteración dei ambien-

te por actividades humanas (tala

de bosques, etc). Así por ejemplo,

la presencia de palpebrosus y, po-

siblemente, trigonatus en Bahia

siempre fue considerada como ne-

gativa, pero evidentemente existie-

ron allá en la época de Spix (Me-

dem, 1958 a: 244-245). Este autor

(cp. et loc. cit.) describió J. mos-

chifer de dicha localidad y, según

Vaillant ( op . cit.: 174, tabla), en

1843 Lemelle — Deville colec-

cionó 2 palpebrosus en Bahia

(mnhnp No. 7526, 920 mm y

mnhnp No. 7528, 1100 mm). Ade-

más Spix & Martius (1828: 636)

se refieren a la localidad exacta,

como sigue (traducido) : “...El

[foso] corre a lo largo dei extremo

oriental dei suburbio Barril. En

este foso viven muchos caimanes

pequenos que poseen un hocico

largo ( Jacaretinga moschifer) y

que despiden un olor de almizcle

muy fuerte...” No obstante, el

término “hocico largo” correspon-

de más bien a trigonatus y, quizás,

ambos coexistieron en esta locali-

dad; es altamente dudoso, sinem-

bargo, que un Paleosuchus actual-

mente existe en un suburbio de

esta ciudad. Por lo general se pre-

sume, que existe un “círculo inter-

no” donde se encuentran ambas

especies y otro “externo” a donde

se extendió únicamente palpebro-

sus. Según los pocos datos exactos

sobre localidades encontradas en la

literatura, parece que fuera así; no

obstante, esta opinión tradicional

es muy posiblemente errónea, ya

que en realidad hay muy pocos es-

túdios detallados al respecto. Por

lo menos no es el caso en el ter-

ritório colombiano, donde la verti-

ente de la Cordillera Oriental for-

Volume 3 (Limnologia)

153

ma el limite de extensión hacia

el norte para ambos Paleosuchus.

En cambio, existen los siguientes

fenómenos, inexplicables todavia.

1) Cuando coexisten ambas espe-

cies, una de ellas siempre es

predominante, como por ejem-

plo, palpebrosus en el Alto y

trigonatus en el Bajo Apaporis

hasta el raudal “La Playa” y

en el Alto Vaupés.

2) Hay vastas regiones donde se

observaron exclusivamente una

u otra especie. Así por ejemplo,

en el Alto Putumayo existe evi-

dentemente trigonatus sólo y

en el Alto Caquetá se observo

también únicamente esta espe-

cie, aunque los nativos infor-

maron que palpebrosus se en-

cuentra muy escasamente; en

cambio, coexisten en el Bajo

Caquetá. Igualmente, se encon-

tro trigonatus sólo en el rio Ca-

fre, parte sur de la Sierra de

la Macarena, mientras ambos

coexisten en el Guayabero-Gua-

viare. En contraste, tanto en la

parte norte de La Macarena

como en los Llanos Orientales

palpebrosus es tan predominan-

te que se puede considerarlo

como el único representante dei

género en estas regiones; ya que

entre 1951 — 1960 se coleccio-

naron dos trigonatus solos de

los rios Sansa y Ocoa respecti-

vamente y no se observo ningún

otro ejemplar más. Indudable-

mente existen uno o vários fac-

tores ecológicos que forman la

causa para esta separación y,

posiblemente, se trata también

de una competência biológica;

de todos mocos será una de las

tareas más llamativas para un

ecólogo tratar de esclarecer es-

tos fenómenos.

CONCLUSIÓN

Entre los Alligatoridae de la

América dei Sur, el género Paleo-

suchus ocupa una posición espe-

cial; por un lado representa un es-

tado muy primitivo de esta familia

desde el punto de vista de la evo-

lución orgânica, y por otra parte

no está condenado a la extinción,

como pasa con muchas formas pri-

mitivas, sino es altamente adapta-

do a la vida en un nicho ecológico

definido y, sobretodo, muy capaz de

competir efectivamente con repre-

sentantes de los géneros más avan-

zados. De las dos especies, P. trigo-

natus representa indudablemente

la forma “básica”, mientras P. pal-

pebrosus la más avanzada y espe-

cializada, debido al grado mayor de

la osificación dei cráneo y dei es-

camado como también a otras ca-

racterísticas morfológicas.

Estos caracteres externos están

estrechamente relacionados con el

nicho ecológico de los Paleosuchus :

el alto grado de osificación de la

cabeza, incluyendo los párpados en

154

Atas do Simpósio sôbre a Biota Amazônica

los adultos, las placas óseas grue-

sas dei escamado, especialmente

en las postoccipitales y cervica-

les constituyen evidentemente una

adaptación protectiva en relación

con la vida entre las rocas de las

aguas correntosas; los dientes pro-

nunciadamente puntiagudos y en-

ccrvados hacia atrás son igualmen-

te bien adaptados para agarrar

presas ágiles y resbaladizas en

aguas caudalosas. El contraste en-

tre los colores de las diferentes par-

tes dei cuerpo y de la cabeza tiene

efecto mimetizante y protector,

tanto en el agua como en tierra.

Movimientos muy ágiles y agresi-

vidad caracterizan ambas especies,

factores que también tienen un va-

lor selectivo.

Los conocimientos sobre las in-

terrelaciones ecológicas son toda-

via demasiado insuficientes para

explicar satisfactoriamente ciertos

problemas acerca la coexistência y

migración.

Existe un paralelismo sorpren-

dente entre las dos especies dei gé-

nero suramericano Paleosuchus y

las dos dei género africano Osteo-

laemus (Crocodylidae ) , osborni y

tetraspis, procedentes dei Congo y

dei África Occidental respectiva-

mente. Este paralelismo se extien-

de hasta detalles como el color,

ciertas características morfológicas

externas, osificación de los palpe-

brales, número de los dientes pre-

maxilares etc. y es discutido por

Kâlin ( op . cit: 707); Mertens (op.

cit: 260) y Inger (1948: 18). Se

trata indudablemente de un caso

típico de la convergência adapta-

tiva, sensu Mayr (1963: 609) y re-

presentaria un problema de mayor

importância para estúdios ecológi-

cos comparativos en el futuro.

Agradecimentos — Me es grato ex-

presar mis profundos y sinceros agra-

decimentos al Dr. José Cândido Melo

Carvalho, Presidente dei Simpósio sôbre

a Biota Amazônica por su amable in-

vitación y la oportunidad que me brin-

do a participar con la presente contri-

bución; al Dr. Enrique L. Diaz, Jefe dei

Departamento por su gran entendi-

miento y apoyo en relación con este

trabajo; al Prof. George Dahl, Conse-

jero Técnico dei mismo quien ha colec-

cionado el material procedente dei Ca-

no Losada; igualmente, me place agra-

decer cordialmente a mis incansables

companeros durante muchas expedi-

ciones, Senhores Carlos Alberto Velas-

quez. Preparador, e Isidoro Cabrera,

Carlos Balcazar, además al Sr. Octavio

Bernal, Dibujante, por su gran entu-

siasmo en elaborar el mapa. Final-

mente, la John Simon Guggenheim

Memorial Foundation en New York la

cual me ha brindado dos veces la opor-

tunidad de elaborar estúdios sobre la

Herpetología colombiana en los Esta-

dos Unidos, merece mis sinceros senti-

mientos de gratitud.

Anexo.

Las Tablas presentadas compren-

den, como sigue:

1) Localidades exactas de P. trigo-

natus en Colombia.

Volume 3 (Limnologia)

155

2) Localidades exactas de P. pal-

pebrosus en Colombia.

3) Dimensiones de 35 ejemplares

de P. trigonatus

4) Dimensiones de 28 ejemplares

de P. palpebrosus.

La dimensión “cuerpo” significa

la longitud desde la punta dei ho-

cico hasta el borde posterior dei

orifício anal, y el término “(reg.)”

que la cola no está completa sino

regenerada y había sido mutilada

a mordiscos durante la lucha in-

traespecífica lo que es muy común

en los Paleosuchus.

El mapa representa las localida-

des de Paleosuchus en Colombia,

con la excepción de los rios Vicha-

da, Casanare y Arauca en los cua-

les no se hizo ningún estúdio, y,

además, los limites de distribución

en la América dei Sur conocidos

hasta la fecha.

SUMARIO

El género Paleosuchus consiste

en dos especies, P. trigonatus (Sch-

neider), 1801, y P. palpebrosus

fCuvier), 1807. Ambos se distin-

guen respecto a sus característi-

cas morfológicas externas (esca-

mado y color) y en la anatomia

craneal. P. trigonatus es el más ge-

neralizado, mientras palpebrosus

poseé caracteres más constantes y,

consecuentemente, es más especia-

lizado. La tendencia hacía la osi-

ficación tanto de los huesos cra-

neales como de las placas derma-

les óseas es más marcada en pal-

pebrosus que en trigonatus. Debi-

do al menor grado de osificación,

en trigonatus la forma dei cráneo

es alargada y la punta dei hocico

recta y angosta; en cambio, en pal-

pebrosus es comprimida, todos cs

huesos individuales son más an-

chos y cortos y la punta dei hoci-

co es ancha y volteada hacia arri-

ba, tanto en ejemplares adultos

como en pequenos juveniles. El co-

lor de la tabla craneal es pardo

oscuro en adultos de trigonatus y

de color de herrumbre en palpe-

brosus; castaho claro en juveniles

de trigonatus y amarillo yema en

palpebrosus. La parte dorsal de los

adultos es pardo oscuro en trigo-

natus y virtualmente negro en pal-

pebrosus. El contraste entre los co-

lores de la cabeza y dei cuerpo tie-

ne un efecto mimetizante en su ha-

bitat natural. El tamaho mayor en

los Sê es de 2256 mm y 1330 mm

para las $ $ de trigonatus, 1720

mm y 1230 mm respectivamente en

los 6 ê y las 9 $ de palpebrosus.

El habitat comprende la Selva

Tropical Pluvial para ambas espe-

cies y el nicho ecológico es bien de-

finido. Consiste principalmente en

aguas caudalosas sobre un fondo

rocoso; muy probablemente el alto

grado de osificación tanto dei es-

camado como dei cráneo y, ade-

rnas, la gran agilidad de los movi-

cm 1

SciELO

10 11 12 13 14 15

156

Atas do Simpósio sôbre a Biota Amazônica

mientos tanto en el agua como en

tierra constituyen una adaptación

a este medio ambiente. A pesar de

que no se ha observado ninguna di-

ferencia marcada acerca dei nicho

ecológico de ambas formas, posible-

mente existe. Así por ejemplo, en

trigonatus la parte dorsal de todos

los ejemplares adultos y subadultos

está siempre cubierta por una den-

sa capa de algas verdes, lo que in-

dica la posible permanência en

aguas mansas y expuestas al sol

por temporadas; en cambio, nunca

se ha observado el mismo fenóme-

no en palpebrosus en su ambiente

natural, sino solamente en cauti-

vidad.

La alimentación es muy variada;

los juvenil es se alimentan princi-

palmente de moluscos acuáticos,

crustáceos e insectos, los adultos de

invertebrados y vertebrados (pe-

ces, ranas y sapos, serpientes, pe-

quenos ejemplares dei mismo gé-

nero y de Caiman sclerops, aves y

mamíferos) ; además se encuen-

tran guijarros en abundancia en

todos los ejemplares mayores de

250 mm. Parásitos, como nemáto-

dos y sanguijuelas ( Hirudinae ),

poco frecuentes; es muy común en

trigonatus un tábano que succio-

na especialmente la zona entre el

espacio interorbital y la punta dei

hocico, la cual es blanda y muy ir-

rigada.

Respecto a la reproducción fal-

tan datos exactos sobre las dimen-

siones de los huevos; la 5 cons-

truye el nido cerca de las orillas

de los canos y bajo dei rastrojo; ni-

dos de palpebrosus que se encon-

traron en Noviembre y Diciembre,

contenían 18 y 22 huevos respecti-

vamente; juveniles de palpebrosus

recién nacidos fueron capturados

en Diciembre 1, 1950; en Enero 6,

1957, se observaron 2 j í y una $

en celos; la disección demostro la

carência de óvulos en los ovários.

Ninguna de estas especies fueron

vistas en grupos sino solitárias; son

principalmente nocturnas; viven

en cuevas excavadas en la orilla

bajo de la superfície de las aguas;

de movimentos rápidos y ágiles,

nadan con gran velocidad contra

la corriente y cambian súbitamen-

te la dirección; ejemplares arpo-

neados saltaron frecuentemente

dentro de las canoas; cuando re-

posan en la orilla, saltan al agua

y no se arrastran como es habitual

en C. sclerops. No son escasos

pero nunca tan abundantes como

C. sclerops.

Dentro de la hoya dei Amazo-

nas propiamente dicha, ambos Pa-

leosuchus tienen una amplia ex-

tensión; trigonatus ha sido regis-

trado en varias localidades situa-

das en el Brasil, Bolivia y Perú y

palpebrosus dei Brasil, Ecuador y

Perú. En Colombia, se extienden

virtualmente hasta la vertiente de

la Cordillera Oriental; trigonatus

ha sido registrado por primera vez

cm 1

SciELO

10 11 12 13 14 15

Volume 3 (Limnologia)

157

en el rio Apaporis, afluente dei Ca-

quetá (Yapurá) en 1952; ambos se

encuentran en los rios Vaupé (Ca-

yarí) , Apaporis, Caquetá y Pu-

tumayo (Iça) y sus respectivos tri-

butários. Existe, sinembargo, un

fenómeno inexplicable hasta la fe-

cha. En vários de estos rios am-

bos son co-existentes, mientras en

otros se encuentran solamente ó

trigonatus ó palpebrosus; en este

caso de la co-existencia, una de las

especies es siempre la más abun-

dante.

El género Paleosuchus, es, qui-

zás, el más primitivo de la Familia

Alligatoridae y evidentemente su

evolución se ha efectuado en épo-

cas geológicas pasadas dentro dei

Habitat de la Selva Tropical dei

sistema hidrográfico dei Amazo-

nas, medio ambiente que virtual-

mente no ha cambiado, sino que to-

davia persiste; su migración y pre-

sencia en otras áreas extensas está

en estrecha relación con su adapta-

ción a un nicho ecológico definido.

BIBLIOGRAFIA SELECCIONADA

Bates, H. W., 1864, The Naturalist on

the River Amazons, with an appre-

ciation by Charles Darwin. XX +

407 pp., figs. sín números, mapas

1-3. Everyman’s Library, London.

Cuvier, G. L„ 1807, Sur les différentes

espèces de Crocodiles vivants et

sur leurs charactères distinctifs.

Ann. Mus. Hist. Nat. Paris, 10:

8-66, pis. 1-2.

Dunn, E. R., 1945, Los géneros de Anfi-

bios y Reptiles de Colombia. IV.

Cuarta y última parte: Reptiles,

ordenes Testudíneos y Crocodilinos.

Caldasia, 3 (13): 307-335, figs. 1-7.

Goeldi, E„ 1898, Die Eier von 13 brasi-

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kungen über Lebens- und Fortp-

flanzungsweise letzterer. Beobach-

tungen aus den Jahren 1884-1897.

Zool. Jb. (Syst.) , 10: 640-676, pis.

26-27, fig. 1.

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species of Alligators. Ann. Mag.

Nat. Hist. London, (3): 10: 327-

331.

Hagmann, g., 1902, Die Eier von Caiman

niger. Zool. Jb. (Syst.), 16: 405-410,

pis. 19-20.

Hagmann, G., 1906-1907, Die Eier von

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der Lebens — und Fortpflanzungs-

weise brasilianischer Reptilien.

Zool. Jb. (Syst.), 24: 307-316, pis.

21-23.

Hagmann, g., 1909-1910, Die Reptilien

der Insel Mexiana, Amazonens-

trom. Zool. Jb. (Syst.), 28: 473-504,

pl. 10.

Inger, R. f., 1948, The systematic status

of the Crocodile Osteoblepharon

osborni. Copeia, 1: 15-19, figs. 1-2.

Kalin, J. A., 1933, Beitrãge zur verglei-

chenden Osteologie des Crocodili-

den-Schádels. Zool. Jb. (Syst.), 57:

535-714, figs. 1-29, pis. 11-16.

Langston, W„ Jr., 1965, Fóssil Crocodi-

lians from Colombia and the Ce-

nozoic History of the Crocodilia in

South America. Univ. Cal. Publ.

Geol. Sei., 52; v-vii, 1-157, figs.

1-48, pis. 1-5.

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Leitão de carvalho. A., 1951, Os Jacarés

do Brasil. Arq. Mus. Nac., Rio de

Janeiro, 42: 127-150, pis. 1-4, map.

1-3.

Luederwaldt, H., 1926, Chave para a

determinação dos Crocodilídeos

brasileiros, com uma lista das es-

pecies do Museu Paulista. Rev.

Mus. Paulista, 14: 387-392.

Mayr, e„ 1963, Animal Species and

Evolution. xiv + 797 pp„ íigs. 2-1-

19-4. Harvard University Press,

Cambridge.

Medem, F., 1952, Palaeosuchus trigona-

tus en Colombia. Lozania ( Acta

Zool. Colomb .) 5: 1-12, figs. l-3b.

Medem, f., 1953, Contribuciones a la ta-

xonomía y distribución dei Yacaré

negro, Palaeosuchus palpebrosus

(Cuvier) en Colombia. Rev. Co-

lomb. Antropol., 1 (1) : 409-419,

figs. 1-2B, map. 1-2.

Medem, F., 1958a, The Crocodilian genus

Paleosuchus. Fieldiana (Zool.), 39

(21): 227-247, figs. 35-39.

Medem, F., 1958 b. Problemas faunís-

ticos de Colombia. El conocimiento

actual sobre la distribución geográ-

fica y ecologia de los Crocodylia

en Colombia. Rev. Univ. Nal., 23:

37-57, figs. 1-16, mapa 1.

Medem, F., 1960, Datos zoo-geográficos

y ecológicos sobre los Crocodylia y

Testudinata de los rios Amazonas,

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(38) : 341-351, mapa 1.

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tada de Reptiles Colombianos. Rev.

Acad. Colomb. Ci. Exact., Fís., Nat ,

12 (47): 299-346.

Medem, F. & Marx, H„ 1955, An Artifi-

cial Key to the New World species

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252-312, pis. 1-12, figs. 1-32.

Müller, L., 1912, Zoologische Ergebnisse

einer Reise in das Mündungsgebiet

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26: 1-41.

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der rezenten Krokodilier. Ztschr .

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16-21, mapas 1-3.

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Alligator de la collection du Mu-

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(3) 10: 143-211, figs. 1-2, pl. 13.

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VEB- Gustav Fischer Verlag, Jena.

Volume 3 (Limnologia)

159

TABLA 1

Especie: Paleosuchus trigonatus

No.

Sexo

Localidad y Fecha

CNHM

81980

d

Rio Cafre, afluente dei rio Guayabero (Meta), Febrero 19, 1957, F. Medem, Modesto

Guevara

Pt

17

d

Misma localidad y fecha

Pt

20

d

Misma localidad, Febrero 20, 1957, mismos colectores

Pt

11

d

Misma localidad, Enero 4, 1957, mismos colectores

Pt

1

d

Alto rio Guayabero, vertiente sur de la Sierra de La Macarena, Enero 22, 1959,

F. Medem

Pt

14

d

Rio Cafre (Meta), Enero 5, 1957, F. Medem & M. Guevara

Pt

12

d

Misma localidad, Enero 4, 1957, mismos colectores

Pt

28

d

Caõo Itilla, cabeeeras dei rio Vaupés (Vaupés), Febrero 26, 1958, F. Medem

CNHM

69882

d

Soratama, rio Apaporis (Vaupés-Amazonas), Abril 2, 1952, F. Medem

CNHM

69879

d

Misma localidad, Abril 11, 1952, F. Medem

Pt

29

d

Caõo Casacunte, afluente dei rio Consaya, Alto Caquetá (Caquetá), Noviembre 28,

Hugo Arévalo

Pt

3

d

Caõo Losada, afluente dei Alto Guayabero (Meta), frente sl La Macarena, Marzo 10,

1959, George Dahl

Pt

4G

d

Caõo Acahé, afluente dei rio Putuma 3 'o, arriba de Pto. Asís (Putumayo), Octubre 23,

1958, F. Medem

Pt

15

9

Rio Cafre, Enero 6, 1957, F. Medem & AI. Guevara

Pt

25

d

Caõo Tacunema (Vaupés), afluente dei Alto Apaporis, campamento “Grito”, Diciembre

30, 1957, F. Medem

Pt

30

9

Caõo Aguas Negras, afluente dei Apaporis, abajo dei raudal “La Playa” (Amazonas),

Agosto 7, 1957, F. Medem

Pt

27

d

Rio Vaupés, abajo dei lago "El Dorado" (Vau pás), Enero 7, 1958, F. Medem

Pt

24

d

Cafio Tacunema (Vaupés), campamento “Grito", Diciembre 30, 1957, F. Medem

CNHM

69881

d

Soratama, rio Apaporis, Marzo 30, 1952, F. Medem

CNHM

69876

d

Misma localidad, Enero 28, 1952, F. Medem

Pt

26

d

Caõo Tacunema, Diciembre 30, 1957, F. Medem

Pt

31

d

Cafio Icapuvá, afluente dei Apaporis, región de Yay-Gojé (Amazonas), 3 horas abajo

dei Pirá-Parani, Agosto 8, 1957, F. Medem, Perimaté Tanimúca

Pt

13

d

Rio Cafre, Enero 4, 1957. F. Medem & M. Guevara

Pt

9

d

Rio Apaporis, arriba de Yay-Gojé (Amazonas), Junio 10, 1952, Isidoro Cabrera

Pt

45

9

Caõo Piõuõa Blanco (Piyuyá), afluente dei Alto Putumayo, abajo de Pto. Asís, Octubre

27, 1958, F. Medem

Pt

16

d

Rio Cafre, Febrero 19, F. Medem & AI. Guevara

CNHM

69877

9

Rio Apaporis, arriba dei campamento cauchero “Soratama", Abril 10, 1952

Pt

19

d

Rio Cafre, Febrero 20, 1957, F. Medem & M. Guevara

CNHM

(19878

d

Rio Apaporis, Soratama, Abril 16, 1952, F. Aledem

Pt

21

d

Rio Cafre, Febrero 20, 1957, F. Medem & M. Guevara

CNHM

69883

d

Cafio Churdcu. afluente dei rio Apaporis (Vaupés- Amazonas 1 , Enero 20, 1952. F. Medem

CNHM

09873

d

Rio Pacoa, afluente dei rio Apaporis, arriba de las lagunas Inani (Uinaná), Febrero 6,

1952. F. Medem, Jaime Gómez

Pt

O

d

Sierra de Macarena (sur), cafio No. 2, afluente dei rio Guayabero, alrededor dei campa-

mento No. 1, Febrero 21, 1959, Carlos Alberto lelásquez

CNHM

69870

d

Rio Apaporis, arriba de Soratama, Diciembre 12, 1952, Carlos Balcázar

CNHM

69888

d.lUY.

Puerto Córdoba, rio Caqueti, arriba de la Pedrera (Amazonas), Octubre 8, 19o2,

Isidoro Cabrera

*

160

Atas do Simpósio sobre a Biota Amazônica

TABLA 2

Especie: Paleosuchus palpebrosus

No.

Sexo

Locâlidad y Fecha

CNHM

69871

d

Soratama, rio Apaporis (Vaupés- Amazonas), Octubre 21, 1951, Isidoro Cabrera

CNHM

69867

d

Rio Cunimía, Sabana de San Juan de Arama (Meta), Marzo 14, 1951, mismo colector

pp

11

d

Cano Cajuy, hacienda San Antonio, 26 km de Viliavicencio (Meta) hacia Pto. López,

Diciembre 30, 1951, Federico Medem & Carlos Alberto Velásquez

pp

5

d

Cafio Aguasclaras, finca Graciela, 3 km al sur de Viliavicencio (Meta), Julio 23, 1956,

mis mos colectores

pp

15

d

Caõo Churúcu, región de Soratama, rio Apaporis, Enero 26, 1952, F. Medem

CNHM

69868

9

Cano Manacales, Sabana de San Juan de Arama (Meta), Marzo 24, 1951, I. Cabrera

Pp

6

9

Cafio Cajuy, hacienda San Antonio, Mayo 19, 1957, F. Medem & C. A. Velásquez

Pp

7

9

Misma localidad y fecha

CNHM

69872

d

Soratama, rio Apaporis, Marzo 30, 1952, F. Medem

CNHM

69874

9

Laguna Inaná (Uinaná), rio Apaporis, caõo entre la segunda y tercera laguna, Febrero

21, 1952, F. Medem

CNHM

69875

d

Misma localidad y fecha

Pp

22

d

Rio Manacacías. afluente dei rio Meta (Meta), hacienda La Venturosa, Diciembre 29,

1960, F. Medem

Pp

30

d

Cafio Aguabonita, afluente dei rio Guejar, frente a la Sierra de La Macarena (norte)

(Meta), Abril 9, 1951, F. Medem

Pp

9

d

Cafio Cajuy, hacienda San Antonio, Abril 6, 1958, C. A. Velásquez & F. Medem

Pp

1

d

Rio Guayabero (Meta), en un pequefio afluente en la sabana frente a La Macarena

(sur), Enero 19, 1959, F. Medem

Pp

2

d

Puerto López, rio Meta, Agosto 28, 1958, C. A. Velásquez

Pp

8

d

Rio Guaviare, remolino “Playa Alta”, arriba de San José dei Guaviare (Vaupés),

Diciembre 31, 1955, F. Medem

FM

370

9

Región de Pto. López (Meta), Noviembre 23, C. A. Velásquez

MVZ

2017

juv.

Caõo Choriaro, vecindad de la finca El Mico (Meta), frente a La Macarena (norte)

Diciembre 1, 1950, Robert C. Stebbins, John Hendrickson dc Carlos Balcázar

CNHM

42701

d 1 juv.

Misma localidad y fecha

MVZ

2018

juv.

Misma localidad y fecha

CNHM

42702

d juv.

Misma localidad y fecha

FM

762

juv.

Cafio Pachaquiaríto, región de Pto. López (Meta), Diciembre 4, 1962, C. A. Velásquez

MVZ

2016

juv.

Caõo Choriaro, Diciembre 1, 1950, R. C. Stebbins, J. Hendrickson <fc C. Balcázar

FM

764

juv.

Caõo Pachaquiaríto (Meta), Diciembre 4, 1962, C. A. Velásquez

FM

766

juv.

Misma localidad y fecha

FM

765

juv.

Misma localidad y fecha

SciELO

10 11 12 13 14 15

cm

Volume 3 (Limnologia)

161

TABLA 3

Crocodylia Paleosuchus trigonatus

Extremidad

No.

Sexo

Total

Cola

Cuerpo

posterior

derecha

posterior

izquierda

mm

CNHM

81980

&

2256

896 (reg.)

1360

320

314

482

467

Pt

17

d

2145

959 (reg.)

1282

300

290

478

445

Pt

20

d

2100

840 (ieg.)

1260

272

275

442

421

Pt

11

d

1984

778 (reg.)

1206

281

282

435

440

Pt

1

d

1775

702 (reg.)

1050

235

243

356

351

Pt

14

d

1602

612 (reg.)

990

233

235

340

351

Pt

12

d

1537

602 (reg.)

935

240

242

350

347

Pt

28

d

147C

653

817

195

190

300

CNHM

69882

d

1365

605

760

201

200

285

289

CNHM

69879

d

1365

585 (reg.)

780

175

180 '

264

270

Pt

29

d

1356

603

753

192

198

275

283

Pt

3

d

1338

533 (ieg.)

805

195

205

310

305

Pt

46

d

1335

460 (faltan

150)

865

210

108 (falta la

mano total)

340

336

Pt

15

9

1330

468 (reg.)

862

323

220

335

332

Pt

25

d

1303

59

712

175

174

278

270

Pt

30

9

1110

455

605

177

174

247

240

Pt

27

d

1073

483

590

150

156

226

228

Pt

24

d

1056

444

592

172

242

250

CNHM

69881

d

1035

473

562

152

153

222

230

CNHM

69876

d

986

391 (reg.)

795

Pt

26

d

935

422

513

133

135

203

205

Pt

31

d

883

486

497

131

138

190

185

Pt

13

d

875

386

489

125

127

188

187

Pt

9

d

817

397

420

/

Pt

45

9

806

364

442

115

116 mm

175

Pt

16

d

795

368

427

117

120

170

168

CNHM

69877

9

750

313 (reg.)

437

124

119

174

172

Pt

19

d

742

353

407

112

108

164

165

CNHM

69878

d

715

330

385

107

109

152

158

Pt

21

d

682

307

375

102

150

152

CNHM

69883

d

677

296

381

/

CNHM

69873

d

660

292

368

/

Pt

2

d

584

315

269

79 mm

82

120

122

CNHM

69870

d

570

235 (reg.)

335

90

89

131

130

CNHM

69888

d juv.

380

214

166

/

i

/

U — 37 121

162

Atas do Simpósio sôbre a Biota Amazônica

TABLA 4

Crocodylia Paleosuchus palpebrosus

No.

Sexo

Total

mm

Cola

mm

Cuerpo

mm

Extremidad

mm

Extremidad

mm

Extremidad

posterior

derecha

mm

Ext remida*

posterior

izquierda

mm

CNHM

69871

&

1545

648 (reg.)

897

/

CNHM

69867

&

1530

662 (reg.)

868

/

pp

11

tf

1419

576 (reg.)

843

/

i

pp

5

tf

1365

540 (reg.)

825

193

189

302

308

pp

15

tf

1261

598

663

/

CNHM

69868

$

1230

550

680

190

191

290

294

Pp

6

9

1216

540

690

172

176

280

278

PP

7

9

1116

546

570

155

148

242

238

CNHM

69872

tf

1101

510

591

157

159

224

223

CNHM

69874

9

1063

491

672

1

/

CNHM

69875

tf

942

462

480

i

/

i

/

Pp

22

tf

917

448

469

120

125

194

195

Pp

30

tf

854

408

450

/

Pp

9

tf

847

404

443

110

115

170

Pp

1

cf

805

390

110

115

166

163

Pp

2

tf

760

367

376

110

112

153

Pp

8

cf

760

336

370

95

98

151

152

FM

370

9

740

345

395

107

110

164

163

MVZ

2017

juv.

565

275

290

67

68

105

CNHM

42701

cf juv.

556

270

286

J

/

MVZ

2018

juv.

521

252

269

66

67

98

CNHM

42702

cf juv.

520

246

274

/

FM

762

juv.

516

248

267

68

70

102

MVZ

2016

juv.

257

130

127

40

41

53

55

FM

763

juv.

255

129

126

38

37

54

55

FM

764

juv.

254

127

130

36

35

53

55

FM

766

juv.

249

124

125

36

38

52

53

FM

765

juv.

248

126

124

38

37

56

57

Atas do Simpósio sôbre a Biota Amazônioa

Vol. 3 (Limnologia) : 163-185 — 1967

RECONNAISSANCE INVESTIGATIONS OF

DISCHARGE AND WATER QUALITY

OF THE AMAZON

THE

ROY E. OLTMAN

Office of Water Resources Research,

Washington, D.C., U.S.A.

(With 8 text-figures)

When the International Associa-

tion for Scientific Hydrology

(IASH) in 1957 began a program

for assessment of river-borne dis-

solved solids from all sources car-

ried to the oceans, the investiga-

tors found little published Infor-

mation on the Amazon River. The

Information on the water dischar-

ge of the Amazon, because of the

wide range in published values, did

not provide a reliable estimate of

average annual discharge upon

which a computation of the annual

dissolved solids load of the river

could be made. On the basis of the

scanty information available to

the investigators, the Amazon ap-

peared to supply about 10 percent

of the total continental water dis-

charge into the world’s oceans.

However, if the estimated Amazon

discharge was in error by as great

a percentage as appeared probable,

the calculated annual salt dis-

charge to the oceans could be se-

riously affected.

This situation led, in May 1961,

to a joint proposal by Luna B. Leo-

pold, then Chief Hydrologist of the

Geological Survey, Walter B. Lang-

bein, Staff Scientist of the Geo-

logical Survey, and Professor H.

0’R. Sternberg, then Diretor, Cen-

tro de Pesquisas de Geografia do

Brasil, Universidade do Brasil, for

measuring the flow, solute load,

and sediment concentration of the

Amazon. Professor Sternberg gain-

ed the backing of Vice Admirai

Helio Garnier Sampaio, Diretoria

de Hidrografia e Navegação, Minis-

tério da Marinha, for logistic sup-

port. The Marinha do Brazil would

supply the necessary gaging vessel

Cooperative investigations by Minis-

tério da Marinha do Brazil, University

of Brazil and U.S. Geological Survey.

cm 1

SciELO

10 11 12 13 14 15

164

Atas do Simpósio sôbre a Biota Amazônica

and the Geological Survey would

provide the gaging manpower and

equipment. Arrangements for the

first of three reconnaissance ex~

peditions to the lower Amazon

were completed in the spring of

1963. Space does not permit

acknowledgment of the assistance

of the many other individuais and

organizations that helped in car-

rying out the reconnaissance work.

Four engineers of the Geological

Survey — Frank C. Ames, Luther

C. Davis, George R. Staeffler, and

the writer — composed the gaging

team, which was most ably assist-

ed by several Brazilian naval of-

ficers. Professor Sternberg assist-

ed the team during much of the

second expedition.

It is the purpose of this paper

to present a few of the notable re-

sults and conclusions obtained by

the joint expedition for the Óbi-

dos location and other pertinent

sites on the lower Amazon. A fi-

nal report, in preparation, will pro-

vide information on all the work

done, including that in the Manaus

vicinity.

ESTIMATES OF AMAZON

DISCHARGE

Scientists conducting a literatu-

re search for information on the

discharge of the lower Amazon may

become confused by the many dif-

ferent estimates of discharge pub-

lished by investigators of South

American or world river discharge.

Table 1 contains a list, from 14

sources, of selected published es-

timates of some aspect of the Ama-

zon discharge, such as stream geo-

metry, mean velocity, and total

discharge made at the general lo-

cation of Óbidos or the mouth. The

earliest estimate in the list is that

of Spix & Martius published in

1831. The latest estimate in the list

is that of the eminent hydrologist

Maurice Pardé published in 1955.

One may note the wide range of

listed values for the average an-

nual discharge at mouth — a ran-

ge from 68,000 (Alexander Sie-

mens) to 204,000 (Military Engi-

neer) .

Upon inspection of the source

documents one finds such per-

plexing circumstances as the

following:

The published estimate for dis-

charge at mouth in the Military

Engineer (1958, 50 (337) : 386) is

credited to Dr. H. P. Guppy. Upon

examination of Dr. Guppy’s tabu-

lation of discharge of large rivers

of the world found in Nature, one

finds that he credited his value for

Amazon discharge (at mouth) to

Elisée Reclus. Thus, the real source

of the estimate published in the

Military Engineer is Reclus. How-

ever, during the compilation of

estimates by Guppy and those in

Military Engineer, the original Re-

clus estimate of 100,000 cm (cubic

meters per second) for the aver-

cm l

SciELO

10 11 12 13 14 15

Volume 3 (Limnologia)

165

TABLE I

Selected published estimates of flow of the lower Amazon River

Source

Date Location

Data of estimate

Remarks

Date or

season

Cross-section

area (m 2 )

Width

(m)

Mean

velocity

m/sec

Discharge

(m 3 /sec)

Spix and

Marti us

1831 Óbidos

Low water

—

0.7

14,000

Wallace

1853 Óbidos

Low water

—

1.62

—

Velocity estimate attributed to

Wallace by F. Katzer

Lallemont

1860 Óbidos

High water

-

319,476

Guppy

1880 Mouth

Annual

—

70,000

Estimate attributed to Reclus by

H. P. Guppy

Smith

1880 Óbidos

Annual

22,500

1,892

(from Penna'l

1.0

21,500

Based on data reported by Penna,

Wallace, and Martins

Selfridge

1882 Parintins

Aug, 3,

1880

—

110,404

Reclus

1895 Óbidos

June

116,000

to 140,000

1,520

to 1,830

2.04

(100,000)

237,000-

286,000

Figure in parenthesis is published

but is apparently in error.

Siemens

1896 Mouth

Annual

-

—

68,000

Basis of estimate unknown.

Katzer

1898 Óbidos

Early July

1896

100,000

1,890

1.2

120,000

From article: “Die Stromenge des

Amazonas bei Óbidos.”

Le Cointe

1922 Óbidos

End of May

1918

Low water

High water

105,000

117,500

1,890

3.15

0.6

1.25

63,000)

146,775)

Float observation at crest of flood.

Area based on soundings of others.

Carvalho

1942 Mouth

Low water

High water

—

60,000

140,000

Jarvis

1945 Óbidos

Annual

—

85,000

Computed on basis of rainfall-

runoff relation.

Parde

1955 Óbidos

Annual

-

—

90,000

100,000

Based mainly on Le Cointe’s

data.

Military

Engineer

1958 Mouth

Annual

—

204,000

How Guppy ’s published 70,000 cm

became 204,000 is unknown

• See list of references at end of report.

age annual discharge for Óbidos

became 70,000 cm at mouth of ri-

ver in Guppy’s table, and 204,000

CI b at mouth in the table in Mili-

iar y Engineer. Furthermore, upon

e xamination of Reclus’ work one

finds the width at the Óbidos nar-

r °ws quoted as 1,520 to 1,830 met-

er s and mean depth quoted as

about 76 meters, which would pro-

vide a cross-sectional area of

116.000 to 140,00 square meters.

Using Reclus’ value of velocity of

8.000 yards an hour equivalent to

2.04 meters per second, one would

compute an average discharge at

Óbidos of 237,000 to 286,000cm.

Thus, the whole chain of published

166

Atas do Simpósio sôbre a Biota Amazônica

estimates (Reclus, Guppy, and

Military Engineer ) is a compound-

ing of errors.

If one accepts the estimates pu-

blished by scientists who actually

visited Óbidos and vicinity and

made personal observations of

channel geometry and stream ve-

locity as reliable estimates, the

data would be narrowed down to

that of Katzer, Selfridge, Spix &

Martius, Wallace, Smith, Le-

Cointe, and Lallemont (note:

Carvalho’s estimate may also be

valid) . These valid estimates apply

to differing river stages; for exam-

ple, Katzer’s observation was made

in early July 1896; Selfridge’s (at

Parintins) in early August 1880.

LeCointe appears to be the most

helpful. He provides for Óbidos a

measured width at the narrows of

1,890 meters (obtained by triangu-

lation) , low water cross section of

105.000 square meters, high-water

coss section of 117,000 square me-

ters, and discharges ranging from

63.000 cm (low water) to

146,775 cm (high water) . Parde,

in his study, based his estimate of

the average annual discharge at

Óbidos largely on LeCointe’s data

and reported it as from 90,000 to

100.000 cm.

One may wonder why estimates

only, instead of measurements, of

the Amazon discharge at Obidcs

are available. The techniques for

gaging large rivers were well de-

veloped during the 19th century.

Revy reported application of com-

pletely satisfactory methods in

measurements of the Paraná at

Rosário made in 1871. Although

the maximum depth of the Rosário

cross section was only 22 meters —

shallow in comparison with the

61-meter maximum depth found in

the discharge measurement at

Óbidos on July 16, 1963 — the sa-

me procedures used for holding the

measuring vessel in place at Rosa-

rio would have worked at Óbidos,

and the current-meter suspension

for measurement of velocities at

Rosário would have been satisfac-

tory at Óbidos. After establishment

of the river gage at Óbidos in 1928

by the Brazilian Government and

the commencement of daily river-

stage readings, the attraction to

measure the flow and develop a

stage-discharge relation for Óbidos

was stronger, for then the annual

flow regime could be completely

charted. The task of determining

the geometry of a selected cross

section on the Amazon at Óbidos

was relatively simple. Although

complete information is not availa-

ble on the techniques used by the

scientists who have reported meas-

ured cross-sectional area, it is pro-

bable that the method fully des-

cribed by Revy as used on the Pa-

raná work for obtaining measured

depths was used on the Amazon.

Depth measurements of a selected

Volume 3 (Limnologia)

167

cross section are made, following

Revy’s method, by sounding with

a weighted line from a ship drif-

ting with the current . In this way,

the sounding line remains nearly

vertical because there is only minor

current drag on it near the bed. As

the ship drifts across the desired

measuring section, the sounded

depth is observed and the location

of ship on the cross section (dis-

tance from either bank) is deter-

mined by standard surveying

methods (sextant readings on flags

located on the ends of a measured

base line established on shore, or

theodolite readings taken to the

ship from a shore-based instru-

ment). With great care and repli-

cation, a very reliable cross sec-

tion could be so measured. The

measurement of stream velocities

could have been obtained by an-

choring the gaging vessel to per-

mit observations of subsurface ve-

locities with standard current me-

ters or by using subsurface floats.

If a few such measurements, refe-

renced to the Óbidos gage, had

been made to cover the range of

discharge from low to high water

and an approximate stage-dischar-

ge relation established for the Óbi-

dos location, a much better esti-

hiate of the average annual dis-

charge at Óbidos could have been

computed.

Although Jarvis’ discharge for

the Amazon at Óbidos is the only

one tabulated known specifically

to be based on rainfall-runoff rela-

tionships, the map of world runoff

published by L’Vovich, also based

on hydrologic calculations, permits

an estimate of the discharge at

mouth to be measured. Jarvis

using data then available to him,

computed the average annual pre-

cipitation for the drainage area

tributary to Óbidos as 1,570 mm.

He based his average annual ru-

noff estimate on a ratio of imnoff

to precipitation of 34 percent. The

estimate one may derive from L’Vo-

vich’s map is equivalent to about

110,000 cm for either the Óbidos or

at-mouth location. Precipitation

data in the Amazon Basin are pre-

sently much more adequate for

assessment of basin average annual

rainfall then was the case for Jar-

vis or L/Vovich. Using Thornthwai-

te’s potential evapotranspiration

approach and the presently avail-

able climatic data, the writer has

calculated average annual runoff

for area above mouth of 800 mm,

equivalent to average annual dis-

charge of 150 000 cm.

RESULTS OF RECONNAISSANCE

WORK

As discussed in Geological Sur-

vey Circular 486, “Amazon River

Investigations — Reconnaissance

Measurements of July 1963,” the

lack of data for discharge and dis-

solved solids of the Amazon ham-

168

Atas do Simpósio sôbre a Biota Amazônica

pered work on the project of the

International Association of Sci-

entific Hydrology (IASH) for cal-

culation of the salt balance of the

oceans. The Amazon River was

known to be the world’s largest in

terms of discharge, but the degree

of uncertainty in the available es-

timates of the discharge led to the

investigations jointly sponsored by

the Brazilian Navy, the University

of Brazil, and the U. S. Geological

Survey. The results collected du-

ring the first measurements (July

1963) reported in Circular 486 have

been supplemented by results ob-

tained in October-November 1963

and August 1964 and will be dis-

cussed in detail in a final report

(in preparation) . The results of

the measurements of flow at Óbi-

dos are discussed in this section;

the measurements of water qua-

lity and sediment are discussed in

a later section.

The major features of the three

measurements of discharge at Óbi-

dos are presented in Table 2.

TABLE 2

Discharge measurements at Óbidos

Date

Stage

(m)

Width

(m)

Area

(m J )

Mean

Depth

(m)

Mean

Velocity

(m/sec)

Discharge

(m 3 /sec)

7/16/63....

5.8

2,290

110,000

48.0

1.97

216,000

11/20-21/63

— 0.5

2,260

92,400

41.0

0.79

72,500

8/ 9/64....

4.76

2,280

106,000

46.5

1.55

165,000

The methods used in collecting

the data for the measurements

have been discussed in Circular

486. All three discharge measu-

rements were made at the same

cross section. The August 1964

measurement used subsurface ve-

locities after loss of a 136-kg sound-

ing weight and current meter on

an under-water obstruction led

the gaging party to conclude it

would be prudent to conserve the

remaining equipment. However,

the depths for the measurement

were taken with a sonic sounder

and the results should be nearly as

reliable as are those of the first

two measurements. The width of

section, ranging from 2,260 to

2,290 meters is different from that

measured by LeCointe (1,890

meters) because the cross section

selected for the 1963-64 work was

Volume 3 (Limnologia)

169

about 2 km downstream from Le-

Cointe’s section.

The datum of the gage used at

Óbidos in 1928-46 and destroyed

(according to local information)

during the great flood of 1953 was

recovered by reference to a photo-

graph (courtesy of Departamento

Nacional de Produção Mineral, Di-

visão de Águas) of the location of

the original high-water staff-gage

section. Fortunately, the Óbidos

municipal warehouse against

which the original staff section had

been photographed existed during

the 1963-64 visits, and by careful

measurements the datum was re-

covered within a possible error

range of 10 cm. Fortunately, also,

overlapping records of river stage

are available at Manaus and Ta-

perinha.

-I

A*

/

j

uly

.-V

/

r

$

.7

gust

)64

-

1

2/

Â

/

*f

/ N

d v e m

ber 1

963

■1953 f lood-

T

July

1963,

3 4 5

TAPERINHA

15

20 25

MANAUS

30

STAGE, IN METESS

Fig. 1 — Concurrent readings on gages Obidos-Manaus-Taperinha .

Figure 1 shows the good agree- Manaus and Taperinha where daily

hient of the concurrent 1963-64 gage readings were available. The

Óbidos readings with those from stage graphs showing the re-

cm 1

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10 11 12 13 14 15

p

170

Atas do Simpósio sôbre a Biota Amazônica

lationship of concurrent readings

for the period 1928-46 (overlapping

records Óbidos and Manaus) and

1931-46 (Óbidos and Taperinha)

were prepared by plotting selected

concurrent readings for the three

gages and fitting the curves to the

scatter plot. There can be no ques-

tion that the Óbidos gage datuin

was recovered with reasonable ac-

curacy, as the concurrent readings

1963-64 lie on the curves develop-

ed from data taken in 1928-46

(1931-46 in the Obidos-Taperinha

comparison). For example: the re-

lationship curve Manaus-Obidos

shows that a stage of about 7.5

meters would have occurred at

Óbidos at the crest of the great

1953 flood, which reached 29.7 me-

ters at Manaus. Similarly, the

Taperinha - Óbidos relation curve

shows that a stage of about 7.6

meters would have occurred at

Óbidos during the 1953 flood,

which reached 6.65 meters at Ta-

perinha. Discussion with Óbidos

inhabitants who remembered the

1953 flood and showed the survey

party the levei it reached in the

vicinity of the gage location veri-

fied the approximate Óbidos stage

of 7.5 meters for the 1953 event.

Thus, significant evidence indica-

tes reliable recovery of the Óbidos

gage datum used in 1928-46.

A rating curve (curve showing

relationship of stage to discharge)

prepared for Óbidos on the basis of

the three available measurements

of discharge and other data is

shown in figure 2.

Guidance in drawing the curve

through the discharge measure-

ments and extending it to the gre-

atest known stage of 7.6 meters

was obtained from a study of con-

veyance and slope. The slope

computed by use of the Manning

formula with a Manning coeffici-

ent (English units) of 0.020 (deri-

vation of the Manning coefficient

from a vertical velocity curve is

explained later) varied among the

three measurements as follows:

July 1963 8.75 X 10 6

November 1963 1.74 X 10 8

August 1964 5.65 X 10°

It is the author’s opinion that

the square root of the slope varies

linearly with stage at and above

the stage of the two higher measu-

rements of discharge. Thus, the

slope estimated for a stage of 7.6

meters at Óbidos is 16.0 X 10 6 .

The stage-conveyance relation for

Óbidos does not vary much with

stage (conveyance, K, equals, in

English units, 1.486 AR- 3

n

where A is cross-sectional area and

R the hydraulic radius) ; hence

the increase in discharge with

stage is mainly a result of increa-

se in slope through the Óbidos nar-

SciELO

10 11 12 13 14 15

cm

Volume 3 (Limnologia)

171

- 4

to

“ 2

-I

j

■|

une 19

-1

53 est

i

mate

/

osuren

uly 196

nent

3

° .

/ Aug

ust 19

64

J

Á

o

L

lember 1963

1 L

0 100 200 300 400

DISCHARGE, IN 1000 CUBIC METERS PER SECOND

Fig. 2 — Stage-discharge relation — Amazon River at Óbidos.

r °ws. An observation by Lecointe

°f the high velocity through the

Óbidos narrows concurrent with

the crest of the flood of May 1918

(3.15 meters/second from float ob-

servation) supports the extrapola-

tion of the stage-discharge relation

t° 250,000 cm at stage 7.6

theters. Figure 3 shows the small

v ariation in cross section measur-

e< t in the Óbidos discharge measu-

r ements. The cross-sectional area

of the main channel for a 7.6

meters would be but 4,150 meters 2

larger (about 4 percent larger)

than that of the discharge measu-

rement of July 1963.

During the three trips for col-

lection of reconnaissance data, li-

mited time did not permit an in-

vestigation of the overflow situa-

tion at Óbidos. Maps (see Figure 4)

clearly show the area subject to

overflow between the main chan-

cm 1

SciELO

10 11 12 13 14 15

172

Atas do Simpósio sobre a Biota Amazônica

nel opposite Óbidos and the terra

firme about 32 km south of Óbi-

dos. The flood plain, judging by

available maps and air photos, is

covered with shallow lakes,

swamps, scrub trees, and grass,

and the drainage channels and

abandoned meanders indicate the

localized flow directions during

floods. A set of leveis run from the

water surface as far inland on the

flood plain as limited time would

permit shows the top of the natu-

ral levee and flood plain adjacent

to the right bank of the main

channel opposite Óbidos to be

about at elevation 6.9 meters (Óbi-

dos gage datum) . Thus, significant

overflow covering the entire flood

plain opposite Óbidos would occur

any time the Óbidos stage exceed-

ed 6.9 meters. It is of interest

that the former Óbidos gage obser-

ver (Mrs. Platt) made a notation

in the gage records that overflow

would begin at Óbidos when the

river levei reached 7.5 meters.

Although overflow directly oppo-

site Óbidos might not begin until

the river stage reached 6.9 meters,

it is very likely that significant

overflow would exist at a 6 . 9-meter

stage through the channels and

lakes (Lago do Poção, Lago Gran-

de de Vila Franca, and connecting

small lakes) occupying roughly a

strip of the flood plain 15 km wide

immediately adjacent to terra fir-

Fig. 3 — Measured cross sections from three discharge measurements.

SciELO

10 11 12 13 14 15

cm

Volume 3 (Limnologia)

173

55° w

2 o S

30

50 M i I es

I

10

50 Ki lometers

Fig . 4 — Map of Amazon River in vlcinity of Óbidos .

me. A computation of possible ran-

ge in discharge over the flood plain

at the stage (7.6 meters) of the

1953 flood was made by (a) assum-

ing the worst possible hydraulic

conditions of shallow depth, wa-

ter-surface slope equal to the main

channel water-surface slope, and

maximum natural roughness and

(b) assuming the best possible hy-

draulic conditions of average depth

of overflow equal to 2 meters, wa-

ter-surface slope increased 50 per-

cent over the main channel slope,

and minimum probable roughness

(Manning coefficient 0.030). The

result based on assumed worst hy-

draulic conditions showed that the

overflow could be ignored without

seriously affecting the accuracy of

the estimated maximum dischar-

ge. The computation based on best

conditions showed that a flow

equal to about 10 percent of the

main channel discharge might by-

pass the main channel at a stage

equal to that of the 1953 flood. It

is likely that the actual overflow

discharge in June 1953 was some-

where between the two results.

Katzer’s interpretation of the

overflow situation at Óbidos is not

favorable por accuracy of flow

measurements. He wrote: “Unfor-

tunately the narrows at Óbidos is

not suitable for this purpose as

long as the entire quantity of wa-

ter is to be determined, because

only a part of the Amazon’s total

water passes at this point. Another

cm 1

SciELO

10 11 12 13 14 15

174

Atas do Simpósio sobre a Biota Amazônica

part flows into a number of arms

in the lowland north of the Serra

do Valaio and helps to fill the lar-

ge lake, Lago Grande de Vila Fran-

ca, which forms a wide water zone

with its numerous lagoons and

their connecting channels. This

water zone stretches like a bow-

string across the main arm of the

Amazon which bends north, and

below whose zenith the city of Óbi-

dos is situated.”

Several strips of overlapping ae-

rial photographs taken on flight

lines across the flood plain from

east to west and north to south

from the terra firme to the Ama-

zon were available to the writer for

study. It is unlikely that the over-

flow situation intimated by Kat-

zer could exist. However, if great

accuracy of measurement of the

total discharge of a subsequent

flood of the size of the 1953 event

is desired, the overflow depths and

current velocities should be mea-

sured and the quantity of flow

computed. It is the writer’s opinion

that the quantity of flow bypassing

the main channel at the stage

equivalent to average annual dis-

charge at Óbidos is an insignifi-

cant percentage of the main chan-

nel flow.

Some questions may be raised

about the fact that the two higher

discharge measurements were

made on a falling river stage and

hence the measured flows may be

less than would occur at equal

stage on the rising side of the

hydrograph. A computation made

by the Wiggin’s formula,

where Qc = discharge corrected for

changing stage; Qm is discharge

measured; U is velocity of flood

wave (assumed equal to 1.3 times

mean velocity) ; Sc is slope of

energy gradient;

d h

— is rate of change of stage in

dt

feet per second,

showed the correction to be applied

to the July 1963 measurement was

less than 3 percent (which can be

ignored in view of the reconnais-

sance nature of the work). The

August 1964 measurement had a

lesser correction computed for it.

Proof of tidal effect at Óbidos

was obtained by stage readings at

short intervals during the Novem-

ber measurement. (The existence

of tidal effect was a moot point ba-

sed on previous investigations.)

The graphs of stage readings ta-

ken at one-half-hour intervals on

November 20 and 21, 1963, are

shown in Figure 5.

It should be kept in mini that

the readings were taken during

one of the lowest flows of the Ama-

zon at Óbidos when the upstream

Volume 3 (Limnologia)

175

reach of tide effect would be a ma-

ximum. (During the period 1928-

-46 no stage reading of less than

0.05 meter was recorded. The mean

stage of the November 1963 dis-

charge measurement is -0 . 5 meter,

or one-half meter lower than zero

datum.) The effect of tide on the

Óbidos stage-discharge relation is

considered insignificant by the

writer .

On the basis of the recorded ga-

ge readings for the period 1928-46

and the rating curve of figure 2,

mean monthly discharge has been

computed as listed :

Month

Average monthly

discharge for pe-

riod (1,000 cm) *

January

110

February . . .

140

March

170

April

215

May

240

June

240

J uly

205

August

165

September

120

October ....

90

November . .

85

December . .

95

* Average rounded to nearest . . .

5,000 cm

The computed annual mean dis-

charge at Óbidos for the period is

157.000 cm. The mean annual dis-

charge computed for Óbidos on the

basis of the three discharge mea-

surements and Óbidos gage rea-

dings for the period 1928-46 is thus

seen to be more than 50 percent

greater than Parde’s estimate of

90.000 to 100,000 cm.

Some observations on velocity

distribution in selected verticais

and in the complete cross section

at Óbidos are shown in Figure 6

and 7.

The point velocity observations

for the vertical distribution of ve-

locities observed on November 21,

1963, were measured while the

corvette was anchored and should

be reasonably free of errors caused

by movements of the metering

vessel during individual observa-

tions. Each point velocity observa-

tion is the average determined

during a period of forty or more

seconds . The effects of natural

stream turbulence are evident

in the scatter of the observa-

tions about the arbitrarily placed

distribution graph. It is evident

that, because of the large scale of

the turbulence, each point velocity

observation should ha ve been deriv-

ed from a meter run of much

longer duration — perhaps as long

as 4 minutes . From a study of data

from 23 United States rivers rang-

ing in depth from 2,4 ft. to 26.7 ft.

(0 . 73 m to 8 . 1 m) , Cárter and An-

derson determined that an obser-

cm 1

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10 11 12 13 14 15

176

Atas do Simpósio sôibre a Biota Amazônica

vation period of 4 minutes for the

20-percent depth location will yield

a mean point velocity within 2 per-

cent of the probable true average.

As predicted by turbulence theory,

the effect of turbulence at the Óbi-

dos section is most pronounced in

proximity to the channel bed and

it decreases as the distance of ob-

servation point above the bed in-

creases.

The vertical velocity curve data

in Figure 6 and the several other

vertical velocity distribution curves

developed for other locations and

dates at Óbidos verify the essential

correctness of the Geological Sur-

vey’s standard procedure for com-

puting the mean velocity in the

vertical as the average of point ve-

locity observations taken at 20 and

80 percent of the total depth. The

mean in each vertical for the Óbi-

dos diácharge measurements of

July and November 1963 was com-

puted from the 20-and 80-percent

depth observations-each corrected

for movement of the measuring

corvette during the period of obser-

vation, as explained in Geological

Survey Circular 486. The mean in

each vertical for the August 1964

measurement was obtained by ap-

plying an appropriate coefficient

to the subsurface velocity.

The distribution of mean veloci-

ty in vertical across the Óbidos

measuring section for the high-

flow measurement of July 1963 is

shown on Figure 7. The distribu-

tion of velocities in the section is

remarkably uniform, as would be

expected from Geological Survey

experience derived from thousands

Volume 3 (Limnologia)

177

Pig_ 6 Distribution of velocity in a selected vertical at Óbidos.

of discharge measurements made

on deep, swift rivers in the United

States with similar uniformity of

measuring section and similar

streambed conditions.

An analysis based on the verti-

cal velocity distribution graph and

the logarithmic velocity distribu-

tion law for wide channels (smooth

or rough) :

V ^ =21o§io (^) +0 - 88

where v is observed point velo-

city (all English units)

12 — 37 121

178

Atas do Simpósio sobre a Biota Amazônica

V is mean velocity in ver-

tical

f is Darcy-Weisbach fri-

ction coefficient

y is depth of observation

(measured from bed)

yo is total depth of mea-

sured vertical

yielded a Darcy-Weisbach friction

coefficient of = 0.008, equivalent

to a Manning roughness coefficient

for the depth investigated of 0.019.

This indication of a relatively

smooth bed is borne out by the bed

profile shown by sonic soundings

and the bed material samples ob-

tained. A section of fathometer

chart taken November 21, 1963, du-

ring a run up the approximate

middle of the channel and Crossing

the general location of the mea-

sured cross section is shown on Fi-

gure 8.

The chart shows dunes with an

approximate length of 200 meters.

(The illustration is a drafted re-

production of the fathometer

chart. The explanation of the short

period fluctuations is unknown.)

Experience with sand channels in

the United States has led to assign-

ment of Manning coefficients in

the range 0.018 to 0.035 for such

bed geometry. The size distribution

of material determined from bed

samples is discussed later.

QUALITY OF WATER

In contrast to the many publish-

ed estimates of water discharge

for the Amazon, there is little pu-

blished information on the sus-

pended sediment and dissolved

solids loads carried by the flow.

Katzer and Sioli have published a

few analyses of suspended sedi-

o

*- Left Right

>■ bank bank

Fig. 7 — Distribution of mean velocity in cross section at Óbidos.

Volume 3 (Limnologia)

179

Depth, in Depth,

meters in feet

40

45

50 1 -

1000 f eel - 25 f eet

(305 m. - 76 m.)

Fig. 8 Section of fathometer chart taken near midstream and Crossing

general location of measuring section.

ment, total dissolved solids, and

some other information on the

Chemical and physical nature of

the Amazon water in the general

vicinity of Óbidos. Pinto is quoted

by Camargo as having computed a

mean daily discharge of suspend-

ed load at mouth of Amazon to be

3 million tons .

Undoubtedly, the lack of means

for collection of suspended sedi-

ment samples from various depths

at the relatively high flow veloci-

ties discouraged investigators from

attempting to assess the mean an-

nual suspended sediment dischar-

ge by Óbidos. Similar difficulties

would have discouraged attempts

to collect samples of the material

•n place on the streambed.

The joint reconnaissance ven-

ture of 1963-64 was well equipped

to collect water samples at any

point in the measuring cross sec-

tion at Óbidos. Samples of the ma-

terial on the top of any part of the

bed could also be taken with an

oceanographic clamshell type sam-

pler or standard U.S. BM-54 sam-

pler. The U.S. P-61 suspended sedi-

ment sampler (equipped with

3/16-inch-diameter intake nozzle),

having an electrically controlled

intake and closure valve, permitted

water samples for analysis of sus-

pended sediment to be taken at

any location in the cross section of

flow. Thus, the distribution of sus-

pended sediment concentration

from bed to surface could be deter-

em 1

SciELO

10 11 12 13 14 15

180

Atas do Simpósio sobre a Biota Amazônica

TABLE 3

Concentration of dissolved and suspended material (ppm)

[mg/l], Amazon River at Óbidos

Constituent

July 16, 1963

Xovember 2°, 1963

August 9, 1964

Discharge (cms)

216,000

72,500

165,000

Sílica (SÍO 2 )

7.0

9.0

Aluminum (Al)

.07

.02

.15

Iron (Fe)

.06

.09

Calcium (Ca)

4.3

10

3.9

Magnesium (Mg)

1.1

.4

.6

Sodium (Na)

1.8

4.2

1.8

Potassium (K)

—

.4

.6

Bicarbonate (HCO 3 I

19

32

16

Sulfate (S0 4 )

3.0

6.4

1.0

Chloride (Cl)

1.9

4.5

1.6

Fluoride (Fl)

.2

0

Xitrate (NO 3 )

.1

0

.1

Total dissolved solids

28

51

21

Hardness as CACO 3

15

27

12

Dissolved oxvgen

5.8

5.6

5.4

Specific conductance

40

84

34

pH

6.5

7.1

6.5

Temperature (°F)

83

86

83

Suspended sediment

89

60

110

mined at any selected vertical. A

bathythermograph furnished tem-

perature-depth profiles at desired

verticais. Chemical-quality samples

were taken with an oceanographic

sampler consisting of an open tube

that allowed flow through of wa-

ter until it was closed, as desired,

by ball-type valves.

The quality of water aspects of

ihe investigation were conducted

by Mr. F. C. Ames, Geological Sur-

vey, Denver, Colorado. Mr. Ames

furnished Table 3, which shows the

results of the three series of sam-

plings made at Óbidos. The tabu-

lated suspended-sediment concen-

trations are the calculated avera-

ge concentration for the cross sec-

tion. Suspended sediment samples

were taken at many points in each

vertical sampled, so that the dis-

tribution of suspended material in

the vertical could be charted. In a

personal communication (April

1966) , Mr. Ames has furnished in-

formation, as follows, on the range

of suspended-sediment concentra-

tions measured in the cross sec-

tion:

November 1963 August 1964

50 mg/l 70 mg/l

280 340

July 1963

Upper portion of verticais 60 mg/l

Near the bed 300

Volume 3 (Limnologia)

181

As expected, the concentration of

suspendei sediment is high in the

vicinity of the bed.

Ames reports (personal coramu-

nication) this information on the

bed material at Óbidos:

“The median diameter of bed

material averaged about 0 . 20 mm.

The median diameters indicated

by individual samples ranged from

0.15 to 0.25 mm. Only one to two

percent of the bed material (by

weight) was finer than 0.062 mm

and only one or two percent was

coarser than 0.4 mm . ”

Katzer reported total dissolved

solids of 56 mg/l in a sample ta-

ken at Óbidos June 30, 1896. Be-

cause the turbulent mixing and

lack of major tributary inflow in

the vicinity of Óbidos (the dischar-

ge from the Rio Trombetas would

have small effect) should guaran-

tee uniformity of dissolved-solids

concentration in a cross section of

the stream, the minor differences

in the four analyses can be attri-

buted to seasonal variations. One

would expect the total dissolved

solids found by Katzer on Ju-

ne 30, 1896, to be more dilute than

he reported unless the flow for that

season was very low. The concen-

tration of dissolved solids on Au-

gust 9, 1964 (discharge 165,000 cm)

if there were a relatively fixed in-

verse curvilinear relation bet-

ween total dissolved solids and wa-

ter discharge, would be expected

to be slightly higher than found

on July 16, 1963, (discharge

216,000cm). The contrary findings,

21mg/l and 28 mg/l t respectively,

show the importance of seasonal

variations in the proportions of to-

tal Óbidos flow contributed by

“white water” and “black water”

tributaries. It is apparent that a

minimum of one water sample per

month collected over several years

would be necessary to describe ac-

curately the dissolved-solids load

variation at Óbidos.

The three determinations of

mean concentration of suspended

sediment in the Óbidos cross sec-

tion also show the need for many

more samples to be taken during

several years before one could cal-

culate a mean annual concentra-

tion of suspended sediment. How-

ever, on the basis of reconnaissan-

ce results at Óbidos, if the mean

annual concentration were assum-

ed to be 100 mg/l, one would ar-

rive at a calculated mean daily sus-

pended load at Óbidos (using

157,000 cm) of about one-half that

which Pinto computed for the

mean daily load at mouth.

The dissolved oxygen content is

close to saturation levei at the ob-

served stream temperature. Bathy-

thermograph results showed no d>

tectable variation of temperature

in any of the verticais where obser-

vations were taken from surface

to bed and return. The pH was

cm l

SciELO

10 11 12 13 14 15

182

Atas do Simpósio sôbre a Biota Amazônica

found to be as expected from the

analyses reported by Sioli for the

vicinity of Santarém.

ESTIMATED DISCHARGE

AT MOUTH

The drainage area tributary to

the Óbidos location is about

5,000,000 sq km (square kilome-

ters) . The drainage area above the

mouth is about 6,000,000 sq km, or

an increase of about 20 percent

over that for Óbidos. If equal con-

tribution of runoff existed for the

basin above mouth, the mean

annual discharge at mouth would

be expected to be about 190,000 cm.

However, there are several data

that indicate the yield per unit

drainage area from the approxi-

mately 1,000,000 sq km of drainage

intervening between Óbidos and

the mouth to be less than that

occurring above Óbidos.

Only two large tributaries, the

Tapajós and the Xingu, enter the

Amazon downstream from Óbidos.

In August 1964, the gaging party

measured the dry season discharge

of the Tapajós at São Luís, loca-

tion of the first rapids, about

300 km upstream from Santarém.

The discharge was found to be

2,840 cm. A stage-discharge rela-

tion for the Tapajós gage at Ford-

landia was drawn on the basis of

the one discharge measurement,

measured geometry of the high-

-flow cross section at São Luís, and

a consideration of the apparent

variation of water-surface slope

with stage for the Tapajós location

at São Luís. On the basis of avai-

lable daily gage readings from the

Fordlandia gage and the cons-

tructed stage-discharge relation, a

mean annual discharge for the Rio

Tapajós has been calculated as. . .

7,100 cm.

No measurement was made on

the Xingu.

A low-water-season measurement

made by the joint survey group on

the Tocantins (not considered an

Amazon tributary) at Marabá in

October 1963 showed the dischar-

ge to be 1,500 cm. Using the cross-

-sectional area at Marabá that

would be occupied by bankful dis-

charge and an estimated mean ve-

locity at bankful stage, the writer

has calculated a bankful discharge

of 33,000 cm. No stage records are

available at Marabá. The mean dis-

charge for the Tocantins was esti-

mated, on the basis of the low-wa-

ter measurement and the estima-

ted bankful discharge, as

11,000 cm.

The Tocantins is not tributary to

the Amazon (its basin has a com-

mon drainage boundary with the

Amazon) but its estimated mean

discharge and that of the Tapa-

jós permit a “bracketing” of an

estimated mean annual discharge

for the Xingu. The sum of mean

Volume 3 (Limnologia)

183

annual diseharges for Tapajós,

Xingu, and minor tributaries bet-

ween Óbidos and the mouth is es-

timated to be 18,000 cm. On this

basis, the partly estimated avera-

ge annual discharge of the Ama-

zon at mouth is 175,000 cm.

Estimates of the runoff from the

intervening area between Óbidos

and the mouth based on the

Thornthwaite potential evapo-

transpiration approach result in a

discharge of about double that ba-

sed on hydrometric data. The esti-

mates based on hydrometric data

are considered to be more reliable

than those based on rainfall-runoff

computations. The writer conclu-

des that the most realiable value

of average annual discharge for

the Amazon at its mouth is

175,000 cm.

CONCLUSIONS

The results of the joint investi-

gations show the previously pub-

lished estimates of mean annual

flow past Óbidos to be much too

low. The mean discharge comput-

ed on the basis of a stage-dischar-

ge relation developed from three

complete discharge measurements

and daily stage readings for the

period 1928-46 is 157,000 cm. The

great flood of 1953 which probably

reached a state of 7.6 meters at

Óbidos is calculated to have dis-

charged at 350,000 cm through the

niain channel with an indetermi-

nate quantity of overflow on the

flood plain.

The observations of dissolved-

solids suspended sediment and

other water-quality parameters

provide much more information on

these aspects for the Óbidos loca-

tion than had been determined

previously, but thre is insufficient

information to permit an accurate

assessment of either the mean an-

nual suspended load or the salt

load discharge. The bed material

samples and fathometer charts

provide much insight into the na-

ture of the streambed at Óbidos.

The objective of the joint inves-

tigation to provide reconnaissance

information on the flow and water

quality of the Amazon was achiev-

ed . If more refined determinations

of the average annual flow and

water quality characteristics are

needed, it will be necessary to con-

duct intensive investigations at

Óbidos and elsewhere in the basin.

The maintenance of a river-stage

gage at Óbidos — above tidal ef-

fects during all but extremely low

flow — would provide valuable in-

formation at small expense.

SUMMARY

Selected published estimates of

the discharge of Amazon River in

the vicinity of Óbidos and the

mouth are presented to show the

great variance of available infor-

mation. The most reasonable esti-

184

Atas do Simpósio sôbre a Biota Amazônica

mates prepared by those who mea-

sured some parameters of the flow

were studied by Maurice Parde,

who concluded that the mean

annual discharge is 90,000 to

100,000 cm (cubic meters per se-

cond). A few published estimates

of discharge at mouth of 110,000

cm based on rainfall-runoff rela-

tionships developed for other hu-

mid regions of the world are avai-

lable .

Three measurements of dischar-

ge made at the Óbidos narrows in

1963-64 by a joint Brasil-United

States expedition at high, low, and

médium river stage are referred to

the datum used at the Óbidos gage

during the period of operation,

1928-46, and a relationship between

stage and discharge prepared on

the basis of the measurements and

supplementary data and compu-

tations. Recovery of the original

Óbidos gage datum is verified by

referring the 1963-64 concurrent

river stages at Manaus, Óbidos, and

Taperinha to gage relation curves

developed for Manaus-Obidos and

Obidos-Taperinha for periods of

concurrent operation, 1928-46 and

1931-46, respectively. Based on the

stage-discharge relation and record

of river stage for the period 1928-46

an average discharge of 157,000 cm

is computed for the Óbidos site.

The greatest known flood at Óbi-

dos, that of June 1953, is comput-

ed to have been a flow of

350,000 cm at stage of 7 . 6 meters

in the main channel with an inde-

terminate amount of overflow

which, under the best assumed

overflow conditions, may have

amounted to about 10 percent of

the main channel flow. Overflow

discharge at stage equivalent to

mean annual discharge is judged

of flow down the main channel .

Miscellaneous data collected du-

ring the flow measurements Show

that the tidal effect reaches up-

stream to Óbidos at extremely low

flows; the distribution of velocities

in stream verticais is affected by

large-scale turbulence; the stan-

dard procedure of basing mean ve-

locity in vertical on the average of

point velocities measured at 20 and

80 percent of the total depth is

valid; and there is a low Manning

roughness coefficient of 0.019

(English units) .

Samples of suspended sediment

taken with a point sampler at va-

rious depths in selected verticais

Show, for the Óbidos site, a varia-

tion in concentration from 300 to

340 mg/l (milligram per liter)

near the streambed to 50 to

70 mg/l in the upper portion of

the verticais. Median diameter of

bed material at Óbidos averaged

about 0.20 mm in a range of 0.15 to

0 . 25 mm. Analyses of water sam-

ples collected at Óbidos in July and

November 1963 and August 1964

are presented.

Volume 3 (Limnologia)

185

The reconnaissance measurem-

ents of 1963-64 provide a well-sup-

ported value of mean armual water

discharge of Amazon River at Óbi-

dos and the mouth. Many more

measurements of flow and water-

quality characteristics are needed

to obtain more exact values of dis-

charge, suspended sediment, and

salt loads.

REFERENCES

Cárter, R. W. & Anderson, I. E., 1963,

Accuracy of Current Meter Measu-

rements. J. Hydraulics Div., ASCE.,

89: No. HY4, Part 1.

Carvalho, D., 1942, Rev. Bras. Geogr.,

4 (2):

Güppy, H. P„ 1880, The Yang-Tse, the

Yellow River, and the Pei-Ho. Na-

ture, 22: 488.

Jarvis, C. S., 1945, River Discharge in

Brazil, South America. Trans.

Amer. Geo. Union, 25th Anniversary

Meeting. Part IV.

Katzer, f„ 1898, Die Stromenge des

Amazonas bei Óbidos. Glolus, 74:

47-49.

Katzer, F., 1897, Das Wasser des untu-

ren Amazonas, Gesellschaft der

Wissenschaften, Prague.

Lallemont, R., 1860, Trip around Nor-

thern Brazil.

Le Conte, P„ 1922, VAmazonie Bresi-

lienne. Paris.

L’Vovich, M. I., 1945, Elements of the

water regime of the rivers of the

earth, Moscow. (Russian) .

Oltman, R. E., Sternberg, H. 0’R„ Ames»

F. C. & Davis, L. C., Jr., 1964, Ama-

zon River Investigations, Recon-

naissance Measurements of July

1963, Geological Survey Circular

486.

Parde, M., 1955, Quelques aperçus re-

latifs a Vhydrologie Brazilienne.

La Houille Blanche, Grenoble.

Pinto, A. O., 1930, Hidrografia do Ama-

zonas.

reclus, E., 1880, The Earth and Its

Inhabitants. Vol. II.

Revy, J. J„ 1874, Hydraulics of Great

Rivers, E. and F. N. Spon, London.

Selfridge, T. O., 1882, The Amazon

River.

Siemens, A., 1896, Cable Laying on the

Amazon River. Nature, 54: 163.

Sioli, H., 1957, Valores De pH De Aguas

Amazônicas. Boi. Mus. Paraense

Emílio Goeldi.

Smith, H. H., 1880, Brazil, The Amazons

and the Coast. London. (Sampson

Low, Marston, Searle, and Riving-

ton)

Soares, L. C., 1956, Amazónia, Excur-

sion Guidebook No. 8, I.G.U. Rio

de Janeiro.

Spix, J. B. & Martius, E. F., 1831 Reise

in Brasilien, Munchen. (Page 1355)

Wallace, A. R., 1853, Traveis on the

Amazon and Rio Negro. Reeve and

Co., London.

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 187-194 — 1967

MOLUSCOS PLANORBÍDEOS DA AMAZÔNIA

W. LOBATO PARAENSE

Instituto Nacional de Endemias Rurais, Centro Nacional de Pesquisas

Malacológicas, Belo Horizonte, Brasil

(Com uma figura no texto)

A fauna de planorbídeos da re-

gião amazônica é ainda muito mal

conhecida, devido às naturais difi-

culdades de trabalho nessa vasta

região e também ao escasso núme-

ro de investigadores interessados

nesse grupo zoológico. Consideran-

do-se tôda a área drenada pelo rio

Amazonas e seus tributários, foram

aí assinaladas até agora 11 espé-

cies de planorbídeos, das quais 6

pertencem ao gênero Bicmphalaria

Preston, 1910, e 5 ao gênero Drepa-

notrema Fischer & Crosse, 1880.

1 . Biomphalaria straminea (Dun-

ker, 1848)

Esta é a espécie de Biomphala-

ria que tem sido encontrada em

maior número de localidades e que

ocupa a maior área de distribuição

aparecendo na literatura amazôni-

ca sob as denominações de Tropi-

corbis (Obstructio) paparyensis

(Baker, 1914), Australorbis centi-

metralis (Lutz, 1918) e Armigerus

( Tropicorbis ) centimetralis (Lutz,

1918). A sua sinonímia foi discuti-

da per Paraense (1963). O reco-

nhecimento da B. straminea na

Amazônia deve-se principalmente a

Sioli (1953), que a coletou nas se-

guintes localidades: Estado do

Amazonas: lago Calado, à margem

norte do baixo Solimões, perto de

Manacapuru; lagos Comprido e

Matafome, no médio Madeira, per-

to de Três Casas; Estado do Pará:

rio Cuminá, afluente da margem

esquerda do Amazonas, perto de

Óbidos; lago Salgado, à margem

leste do rio Cuminá, cêrca de

50 km ao norte de Oriximiná, na

foz do Trombetas (fazenda Tim-

bó) ; lago do Tracoá, à margem do

rio Cuminá, em frente ao lago Sal-

gado; lago do Tostão, à margem

norte do rio Amazonas, entre Óbi-

dos e Alenquer; lago Grande Ca-

cheie de Pesquisas do Conselho Na-

cional de Pesquisas.

188

Atas do Simpósio sôbre a Biota Amazônica

ruaí, em Caraubal, entre Parintins

e Santarém; Santarém; Jacaré

(Retiro Daniel de Carvalho), em

frente a Aveiro; Pindobal, pôrto

de Belterra; Fordlândia; lago Tim-

bó, perto de Curi; rio Cupari, per-

to de sua foz e perto de Flechal;

lagos Caxias e Curuçá, à margem

direita do baixo Cupari; rio Anipe-

ri, afluente da margem direita do

rio São Manuel, perto de sua foz.

O material acima referido foi es-

tudado por Haas (1949 a, b, 1952),

que o identificou ao Tropicorbis

( Obstructio ) paparyensis.

No Estado do Pará a B. strami-

nea foi também assinalada em Be-

lém (Costa, 1952; Pinto & Des-

landes, 1953). No Estado do Acre

foi coletada em Cruzeiro do Sul e

Rio Branco (Paraense, não publi-

cado). No Estado de Goiás foi en-

contrada em Arraias, à margem es-

querda do rio do mesmo nome,

afluente do rio da Palma que dre-

na para o Tocantins através do rio

Paranã (Cunha Neto, comunicação

pessoal) .

Na localidade de Fordlândia, à

margem direita do baixo Tapajós,

a B. straminea transmite a esquis-

tossomose mansoni no único foco

até agora conhecido dessa parasi-

tose na bacia amazônica, descober-

to por Machado & Martins (1951).

Êstes autores examinaram 400 es-

pécimes esmagados entre lâminas,

com resultado negativo para Schis-

tosoma. Resultados idênticos foram

obtidos por Maroja e por Sioli

(Maroja, 1953) e por mim, ao exa-

me de 100, 900 e 5.000 espé-

cimes, respectivamente. Experi-

mentalmente obtive a infecção de

3 entre 28 espécimes expostos, cada

um, a 10 miracídios de S. mansoni

de Belo Horizonte.

A B. straminea ocorre na Vene-

zuela, nas três Guianas, no Para-

guai, no norte da Argentina e em

todos os sistemas de drenagem do

território brasileiro com exceção

apenas da bacia do Uruguai, do

lado oriental da bacia do Paraná

e da área que drena para o Atlân-

tico ao sul do paralelo 21°.

2. Biomphalaria schrammi (Cros-

se, 1864)

Na região amazônica esta espé-

cie até agora foi encontrada ape-

nas em Belém por mim próprio

(Paraense, Fauran & Courmes,

1964). Ela tem sido também assi-

nalada nas Antilhas, na Guiana

Francesa e no Brasil, onde tem o

seu limite sul no Estado de São

Paulo. Entre os seus sinônimos

mais conhecidos contam-se Planor-

bis janeirensis Clessin, 1884 e P. ni-

grüabris Lutz, 1918.

3. Biomphalaria amazônica Pa-

raense, 1966

Esta espécie, que descrevi recen-

temente em material coletado pelo

Instituto Nacional de Pesquisas da

Volume 3 (Limnologia)

189

Fig. 1 — uistnouu^ao aos pianorbiaeos até agora reconhecidos

na região amazônica.

Amazônia, foi encontrada até ago-

ra apenas em Manaus e na ilha do

Careiro, situada à margem direita

do rio Amazonas, em frente à de-

sembocadura do rio Negro. Segu-

ramente deve ocorrer em outras lo-

calidades, o que será demonstrado

por estudos futuros.

4. Biomphalaria lauricochae (Phi-

lippi, 1869)

Espécie do lago Lauricocha, nas-

cente do rio Marahon, no Peru,

foi descrita com base nos ca-

racteres exclusivamente conquilio-

lógicos. São necessários estudos

anatômicos para definição de sua

verdadeira identidade. Segundo

Harry (1962), trata-se de provável

sinônimo da Biomphalaria andeco-

la (Orbigny, 1835) do lago Titi-

caca.

5 . Biomphalaria raimondi

lippi, 1869)

(Phi-

Êste planorbídeo, como o ante-

rior, também não está ainda bem

definido. Foi coletado “em riachos

das florestas da região do Peru cha-

mada Pampa dei Sacramento”,

SciELO

ABiomphalaria atraminea

^B. amazônica

^8. ochrauBni

AB. lauricochae

AB. raimondi

A3. philippiana

ODrepanotrema anatinum

OD. lucidun

CD. depre 8 sÍ 83 Íraum

©D. cimex

cm

10 11 12 13 14 15

190

Atas do Simpósio sôibre a Biota Amazônica

vasta pcrção da Amazônia perua-

na que se estende entre os rios Uca-

yali e Huallaga.

6 . Biomphalaria philippiana

(Dunker, 1848)

A descrição original desta espé-

cie refere-se a material de Cocha-

bamba, na Bolívia, situada nas ori-

gens de tributários dos rios Beni e

Mamoré. Em 1953, o Dr. Ennio Luz

coletou em Morretes (Estado do

Paraná) espécimes de um planor-

bídeo que enviou a Lucena e que,

a pedido dêste (Lucena, 1956: 92),

foram determinados por Bequaert

como Tropicorbis philippianus

(Dunker, 1848). Mais tarde Pa-

raense & Deslandes (1958 b) estu-

daram exemplares pertencentes à

mesma população de Morretes, tra-

tando-os como philippianus por já

ter sido êste nome aplicado à refe-

rida população. De acordo com os

dados de que disponho atualmente,

êste planorbídeo distribui-se pelos

Estados do Paraná, Santa Catari-

na e Rio Grande do Sul, e mante-

nho séria dúvida quanto a ser êle

idêntico ao verdadeiro philippianus

de Cochabamba. Barbosa, Barbosa

& Carneiro (1958) estudaram, sob

a denominação de Tropicorbis phi-

lippianus, um planorbídeo de Gua-

iaquil (Equador) cuja anatomia é

diferente da dos espécimes do sul

do Brasil e assemelha-se à da

Biomphalaria peregrina (Orbigny,

1835) . Comparando conchas dos

espécimes estudados por Paraen-

se & Deslandes e por Barbosa,

Barbosa & Carneiro com o mate-

rial depositado no Museu Britâni-

co, observou Hubendick (1962) que

“o material tipo desta espécie no

Museu Britânico é perfeitamente

semelhante conquiliològicamente à

concha figurada por Paraense &

Deslandes, 1958, a qual, entretan-

to, não é topotípica. O material de-

terminado por Morrison como

T. philippianus e estudado por

Barbosa et dl. 1958 òbviamente não

pertence à mesma espécie, mas é

provàvelmente idêntico ao T. ha-

vanensis.”

Como se vê, a identidade da ver-

dadeira Biomphalaria philippiana,

a de Cochabamba, ainda precisa

ser estudada pelos métodos moder-

nos de investigação malacológica.

Caso seja diferente da espécie do

sul do Brasil, terá esta de receber

outro nome.

7. Drepanotrema anatinum (Or-

bigny, 1835)

Foi coletado pela Expedição

Stanford em um lago artificial em

frente à Catedral de Belém (Baker,

1914) e aparece nas Ests. 79 (Fi-

guras 16-18) e 124 (Figs. 1-3) da

monografia de Baker (1945) com a

indicação “Pará, Brazil”, provàvel-

mente referindo-se a Belém.

Em material coligido por Sioli

(1953) e identificado por Haas

Volume 3 (Limnologia)

191

(1949 a, b, 1950, 1952) como Gy-

raulus ( Drepanotrema ) anatinus,

aparece esta espécie nas seguintes

localidades, quase tôdas comuns à

Biomphalaria straminea : Estado

do Amazonas: lago Calado, no bai-

xo Solimões; lagos Comprido, Ma-

tafome e Paxiúba, no médio Madei-

ra; Estado de Mato Grosso; rio Ju-

ruena, à margem direita; lago do

Peri, no rio Juruena, perto da Bar-

ra do São Manuel; Estado do Pará:

rio Cuminá, perto da fazenda Tim-

bó; lago Salgado; rio Branco de

Óbidos, na sua desembocadura no

lago Mamuru; lago Grande Curuaí,

em Caraubal; Santarém; Fordlân-

dia; lago Curi; rio Cupari, perto de

sua foz e perto de Flechal; lagos do

Caxias e Curuçá, no baixo Cupari.

Entre o material enviado a êste

Centro, para identificação, pelo

Instituto Nacional de Pesquisas da

Amazônia, tem sido reconhecido o

D. anatinum em amostras de Ma-

naus e da ilha do Careiro, Estado

do Amazonas. A sua presença no

Peru foi assinalada por Baker

(1945, Est. 124, Fig. 30), que apre-

senta a concha de um espécime de

Yurimaguas (incorretamente gra-

fada “Juminaguas”) , localidade à

margem esquerda do rio Huallaga,

Departamento de Loreto.

O D. anatinum é encontrado, sob

várias denominações, nas Antilhas,

no México, na América Central e

na América do Sul a leste dos An-

des, chegando até a Argentina. A

oeste dos Andes encontrei-o no

Equador.

8. Drepanotrema lucidum (Pfeif-

fer, 1839)

Foi coletado por Sioli e identifi-

cado por Haas (1949a, 1952), sob

a denominação de Gyraulus ( Dre-

panotrema ) schubarti (Haas, 1938)

na Fordlândia (Pará) e no lago

Matafome, médio Madeira (Ama-

zonas) . Sioli (1953) encontrou-o

no lago Grande Curuaí, perto de

Caraubal (Pará) . Identifiquei-o em

material da ilha do Careiro (Ama-

zonas), de Cruzeiro do Sul e Rio

Branco (Acre) e de Pôrto Velho

(Rondônia) .

No Peru foi assinalado por Baker

(1945, Est. 124, Figs. 29, 31, 32) em

Yurimaguas, juntamente com o

D. anatinum. O planorbídeo de

Buena Vista, Santa Cruz (Bolívia) ,

que aparece sob a denominação

de Drepanotrema paropseides na

Est. 124, Figs. 14-20, da monogra-

fia de Baker (1945) , parece perten-

cer realmente à espécie D. lucidum.

Esta espécie corresponde ao D.

melleum (Lutz, 1918). Sua distri-

buição compreende a região das

Antilhas e a América do Sul a les-

te dos Andes.

9. Drepanotrema depressissimum

(Moricand, 1839)

Sob o nome de Gyraulus {Drepa-

notrema) depressissimus, foi iden-

192

Atas do Simpósio sôibre a Biota Amazônica

tif içado por Haas (1949 a) no rio

Cupari, perto de sua foz (Estado do

Pará), em material coletado por

Sioli. No Estado do Amazonas tem

sido encontrado na ilha do Carei-

ro, perto de Manaus, em coletas do

Instituto Nacional de Pesquisas da

Amazônia, conforme identificação

feita neste Centro.

O D. depressissimum foi assina-

lado até agora nas Antilhas e no

Brasil, distribuindo-se neste país

desde o extremo norte até o Esta-

do de São Paulo.

10. Drepanotrema kermatoides

(Orbigny, 1835)

Sioli coletou esta espécie no

igarapé do Guaranazal, pequeno

afluente do rio Cupari (Pará) , que

foi identificada como Gyraulus

(Drepanotrema) kermatoides por

Haas (1949 b).

O D. kermatoides distribui-se

pelo oeste do Brasil, através de

Goiás e do oeste de Minas, na di-

reção do Paraná, Santa Catarina

e Rio Grande do Sul, estendendo-se

para o Paraguai, Uruguai e Argen-

tina. A oeste dos Andes ocorre no

Peru e no Equador.

11. Drepanotrema cimex (Mori-

cand, 1839)

Coletei esta espécie em Fordlân-

dia (Pará). Sua distribuição com-

preende as Antilhas e, na América

do Sul, comprovadamente o Brasil

e o Uruguai.

A identificação da maioria das

espécies acima referidas poderá ser

feita sem dificuldade de acordo

com as descrições conquiliológicas

e anatômicas constantes dos traba-

lhos de Paraense & Deslandes so-

bre B. straminea = centimetralis

(1955), D. anatinum (1956 a),

D. lucidum — melleum (1956 b),

D. depressissimum (1957), D. ci-

mex (1958 a), B. philippiana

(1958 b), D. kermatoides (1958 c),

de Paraense, Fauran & Courmes

sôbre B. schrammi (1964), e de

Paraense sôbre B. amazônica....

(1966).

SUMÁRIO

Como contribuição ao inventário

da biota amazônica, um dos prin-

cipais objetivos dêste Simpósio, são

apresentados os dados existentes

sôbre a distribuição das espécies de

planorbídeos da região Amazônica.

Esta região é considerada aqui no

seu sentido hidrográfico mais am-

plo, abrangendo tôda a área drena-

da pelo rio Amazonas e seus tribu-

tários, mas não inclui as áreas con-

vencionalmente consideradas como

extensões da Amazônia, como por

exemplo a zona Bragantina do

Pará e a parte vizinha do Mara-

nhão, onde ocorrem planorbídeos,

inclusive transmissores da esquis-

tossomose mansoni.

São as seguintes as espécies de

planorbídeos assinaladas na Ama-

zônia: Biomphalaria straminea

Volume 3 (Limnologia)

193

(Dunker, 1 8 4 8), B . schrammi

(Crosse, 1864) , B . amazônica Pa-

raense, 1966, B. lauricochae (Phi-

lippi, 1869) , B. raimondi (Philippi,

1869) , B. philippiana (Dunker,

1848) , Drepanotrema anatinurn

(Orbigny, 1835) , D. lucidum (Pfeif-

fer, 1839) , D. depressissimum (Mo-

ricand, 1839), D. kermatoides (Or-

bigny, 1835) e D. cimex (Moricand,

1839).

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water mollusks of the Stanford Ex-

pedition to Brazil. Proc. Acad. Nat

Sei. Philadelphia, 65: 618-672.

Baker, F. C., 1945, The molluscan fa-

mily Planorbidae. xxxvi + 530 pp.,

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Barbosa, f. S., Barbosa, I. & carneiro,

E., 1958, The anatomy of Tropicor-

bis philippianus (Dunker) and its

relationships to the Brazilian Pla-

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Costa, O. R., 1952, Contribuição ao co-

nhecimento da esquistossomose na

Amazônia. Rev. Serv. Esp. Saúde

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Crosse, H., 1864, Description d’espèces

nouvelles. J. Conchyliol., 12 (2) :

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Dunker, w., 1848, Diagnoses specierum

novarum generis Planorbis collec-

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Soc. London, 16: 40-43.

Haas, F., 1949a, On fresh water mol-

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Haas, F., 1949b, Land- und Süsswasser-

mollusken aus dem Amazonas-Ge-

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Haas, F., 1950, Some land and fresh-

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Haas, F„ 1952, South American non-

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Harry, H. W., 1962, A criticai catalogue

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of Neotropical Planorbidae. Mala-

cologia, 1 (1): 33-53.

Hubendick, B„ 1962, Report on studies

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Planorbidae. 5 pp. mimeografadas,

Gothenburg.

Lucena, d. T„ 1956, Resenha sistemática

dos planorbídeos brasileiros. 104

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Machado, W. G. & Martins, C., 1951,

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Maroja, R. C., 1953, Incidência da es-

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et fluviatilium molluscorum, in suo

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ture of Brazilian planorbids. III.

Australorbis stramineus (Dunker,

1848). Rev. Brasil. Biol., 23 (1) : 1-7.

13 — 37 121

194

Atas do Simpósio sôbre a Biota Amazônica

Paraense, W. L., 1966, Biomphalaria

amazônica and B. cousini, two new

species of Neotropical planorbid

molluscs. Rev. Brasil. Biol., 26 (2).

Paraense, W. L. & Deslandes, N., 1955,

Studies on Australorbis centime-

tralis. I. Morphology, in comparison

with A. glabratus. Rev. Brasil. Biol,

15 (3): 293-307.

Paraense, W. L. & Deslandes, N., 1956a,

The Brazilian species of Drepano-

trema. I. D. anatinum (Orbigny,

1835). Rev. Brasil. Biol., 16 (4):

491-499.

Paraense, W. L. & Deslandes, N., 1956b,

The Brazilian species of Drepano-

trema. II. D. melleum (Lutz, 1918).

Rev. Brasil. Biol., 16 (4) : 527-534.

Paraense, W. L. & Deslandes, N„ 1957,

The Brazilian species of Drepano-

trema. III. D. depressissimum (Mo-

ricand, 1837) . Rev. Brasil. Biol., 17

(3): 339-344.

Paraense, W. L. & Deslandes, N„ 1958a,

The Brazilian species of Drepano-

trema. IV. D. cimex (Moricand,

1837). Rev. Brasil. Biol., 18 (2):

187-192.

Paraense, W. L. & Deslandes, N., 1958b,

Another Brazilian species of Ta-

phius. Rev. Brasil. Biol., 18 (2) :

209-217.

Paraense, W. L. & Deslandes, N., 1958c,

The Brazilian species of Drepano-

trema. VI. D. kermatoides (Orbigny,

1835) . Rev. Brasil Biol., 18 (3) :

293-299.

Paraense, W. L., Fauran, P. & Courmes,

E., 1964, Observations sur la mor-

phologie, la taxonomie, la réparti-

tion géographique et les gites

d’ Australorbis schrammi. Buli. Soc.

Paih. Exot., 57 (6) : 1236-1254.

Pfeiffer, L., 1839, Bericht über die Er-

gebnisse meiner Reise nach Cuba

im Winter 1838-1839. Weigmanns

Arch. Naturg., 5 (1) : 346-358.

Philippi, r. a., 1869, Diagnoses mollus-

corum terrestrium et fluviatilium

peruanorum. Malak. Blat., 16: 32-

-42.

Pinto, D. B. & Deslandes, N., 1953, Con-

tribuição ao estudo da sistemática

de planorbídeos brasileiros. Rev.

Serv. Esp. Saúde Públ, 6 (1) : 135-

-167.

Sioli, H„ 1953, Limnologische Untersu-

chungen und Betrachtungen zur

erstmaligen Entdeckung endemis-

cher Schistosomiasis ( Sch . man-

soni) im Amazonasgebiet. Arch.

Hydrobiol., 48 (1): 1-23.

SciELO

10 11 12 13 14 1

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 195-200 — 1967

PRIMEIROS RESULTADOS DE PESQUISAS ETOLÓGICAS

EM INVERTEBRADOS LÍMNICOS DA AMAZÔNIA

WERNER SATTLER

Instituto Hidrobiológico da Sociedade Max-Planck, Estação Potamológica,

Schlitz (Hessen), Alemanha

(Com 4 figuras no texto)

Em geral, distinguem-se vários

grupos ecológicos-etológicos de lar-

vas de Efemeróptercs (Needham,

Traver & Hsu, 1935; Wesenberg-

Lunci, 1943), dos quais as larvas

escavadoras provàvelmente têm o

comportamento mais diferenciado.

Enquanto representantes do gru-

po dos “revolvedores” (sprawlers)

(p. ex Potamanthus) , que podem

ser considerados como precursores

das formas escavadoras, movimen-

tam-se na lama fôfa em todos os

sentidos sem deixar rastro nítido,

as larvas escavadoras propriamen-

te ditas produzem túneis irregula*

res no substrato, que se podem ra-

mificar e que se desfazem pouco

depois de serem construídos ( Ephe -

mera) (Wesenberg-Lund, 1943;

Sattler, no prelo) , ou então os tú-

neis não se ramificam, têm forma

de U e são permanentes (Poiymi-

tarcis, Tortopus) (Réaumur, ....

1734 42; Fric & Vávra, 1901) .

As larvas escavadoras na litera-

tura são geralmente indicadas su-

màriamente ccmo devoradoras de

lama e de minhocas (Despax,

1949). Isto, entretanto, não vale

para a larva palaeotrópica Povilla,

que mina em esponjas de água doce

e em pau submerso. Ela reveste os

túneis com uma secreção produzi-

da pelos tubos de Malpighi e elimi-

nada pelo ânus. Com movimentos

respiratórios das brânquias a lar-

va conduz uma corrente de água

pelo túnel, da qual partículas co-

mestíveis suspensas na água são

filtradas. Isso acontece por meio de

tufos de cerdas localizadas na ca-

beça e nas patas anteriores (Har-

tland-Rowe, 1953, 1958) .

Pesquisas nas larvas neotropicais

do gênero Asthenopus (Sattler,

no prelo), mostraram que, nelas,

a evolução de devorador de lama

para filtrador progrediu mais ain-

da. As larvas roem, com suas im-

cm l

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10 11 12 13 14 15

196

Atas do Simpósio sôbre a Biota Amazônica

Fig. 1 — Túnel em forma de U, de Asthenopus, a parede divisória

de lascas de madeira.

ponentes mandíbulas, a madeira

submersa na água, construindo ga-

lerias cuja curva estreita em U pro-

vém da acumulação, entre os dois

braços do U, de lascas roídas cola-

das com a secreção dos tubos de

Malpighi (fig. 1). Trata-se, pois, de

um verdadeiro trabalho construti-

vo e não só, como de costume, de

uma escavação destrutiva do subs-

trato. O aparelho filtrante consis-

te de longas cerdas em 8 tufos com

forma de funil. Em cada lado do

animal acham-se dois tufos na tí-

bia, um no fêmur da pata anterior

e um na base do lado exterior da

mandíbula (fig. 2). Todos os funis

são dirigidos para frente contra a

corrente de água respiratória e pre-

enchem o diâmetro do túnel. Tôdas

as cerdas dos funis possuem duas

filas de finos pêlos, dirigidos para

um só lado. e a distância entre um

e outro mede ca. 4 u. Com isso o

efeito do aparelho filtrante torna-

-se bastante aumentado. A secre-

ção produzida pela larva, não só

cola as lascas da parede divisória,

Volume 3 (Limnologia)

197

mas reveste também as outras pa-

redes da galeria, alisando-lhe irre-

gularidades e evitando assim fen-

das entre as paredes e os tufos de

cerdas, que possam perturbar a fil-

tração.

A larva de Asthenopus pode,

pois, por meio de sua atividade

construtiva e com sua disposição

morfológica com cerdas, ganhar

minúsculas partículas comestíveis

das águas geralmente cristalinas

dos igarapés amazônicos, ficando

ela mesma num abrigo seguro.

Com os mesmos princípios, po-

rém de maneira completamente di-

ferente, a larva do Tricóptero Ma-

cronema, que vive no mesmo bió-

topo, descobriu igual fonte de ali-

mento. Esta larva também faz um

abrigo, pelo qual a água, doadora

de alimento, flui, e ela também dis-

põe de um aparelho filtrante. Cer-

das especiais na cabeça e nas pa-

tas anteriores servem à alimenta-

ção.

Gêneros parentes afastados

(Holocentropus, Plectrocnemia) so-

mente constróem abrigos tubifor-

mes e irregulares, feitos da secre-

ção filiforme das glândulas labiais

e ampliados em frente em forma

de um funil para captura. Gêneros

parentes mais próximos de Macro-

iiema (Rhyacophylax, Hydropsy-

che, Diplectrona) fazem tubos de

FiK. 2 — Larva de Asthenopus. vista diayonalmente de frente,

mostrando o aparelho filtrante (F, T, M = tubos de cerdas,

F - do fêmur. T = da tibia, M — da mandíbula).

SciELO

cm

10 11 12 13 14 15

198

Atas do Simpósio sôbre a Biota Amazônica

Fig. 3 — Abrigo da larva de Macro-

nema ( A . = chaminé de saída de água,

Bb. = solo do igarapé, E. = chaminé de

entrada, EW. = entrada do tubo de

moradia, N. = teia, NK. = câmara para

teia, R. = moldura da teia, S. — areia,

T. = argila, Wa. = água, Wr. = tubo

de moradia) .

secreção e material heterogêneo,

que têm em frente, em vez de fu-

nil, uma teia plana de malhas re-

tangulares (ca . 300x200 (i) muito

regulares .

O tubo e a teia de Macronema,

entretanto, evolucionaram para

uma das construções de animais

mais complicadas, que conhece-

mos (Sattler, 1963). Do simples

tubo de Rhyacophylax etc. desen-

volveu-se um sistema de quatro tu-

bos (com chaminé para entrada,

outro para saída da água, câma-

ra para teia, tubo de moradia),

cuja parte inferior está metida no

solo do igarapé e que é colado com

areia e secreção das glândulas sa-

livares (fig. 3). As duas chaminés

estão dispostas de tal maneira, que

na embocadura de entrada age a

pressão total P_. da água corren-

te do igarapé e na embocadura de

saída age somente a pressão está-

tica P.. Da diferença das pressões

P e — P< resulta, que pelos tubos e

pela teia estendida na sua câmara

constantemente flui água (Sat-

tler & Kracht, 1963). A teia é

construída pelo mesmo princípio

dos gêneros parentes; tem também

malhas retangulares de uma extre-

ma regularidade, que parecem ser

feitas à máquina (fig. 4). Mas são

tão minúsculas, que não menos do

que 630 — 4.300 delas cabem

numa malha de Rhyacophylax;

medem ca. 2-4 x 14-24 u. Os poros

dêste aparelho filtrante têm, pois.

Volume 3 (Limnologia)

199

tamanho correspondente ao da lar-

va de Asthenopus. Os tufos de cer-

das na cabeça e nas patas anterio-

res de Macronema, que seus paren-

tes não possuem, apesar de terem

semelhança com as de Asthenopus,

não servem à filtração mas para

apanhar as partículas comestíveis

da teia.

Para ter uma idéia do tripton or-

gânico (partículas de origem orgâ-

nica transportadas pela água cor-

rente) levado das águas de iga-

rapés amazônicos, foram tiradas

amostras de água de um lugar,

onde os dois tipos de larvas vivem

um ao lado do outro, e passadas

por um filtro membranoso de po-

ros com 0,45)1 (Sattler, 1963).

Disso resultou que 1 cm :! desta

água só continha 4 partículas com

diâmetro maior de 100 p, 208 par-

tículas entre 100 e 30 u, mas 12.925

partículas entre 30 e 3 p. Estas par-

tículas da última categoria, que

não obstante o número relativa-

mente grande delas, não turvam a

água dos igarapés amazônicos, re-

presentam evidentemente a base

de alimentação dos dois tipos de

larvas.

Agradecimentos — As pesquisas fo-

ram realizadas, em parte, com auxílio

do Conselho Nacional de Pesquisas, Rio

de Janeiro, ao qual dirijo agradeci-

mentos.

RESUMO

É estudado o comportamento

construtivo e a alimentação de

200

Atas do Simpósio sobre a Biota Amazônica

duas larvas aquáticas dc inse-

tos, ( Asthenopus , Ephemeroptera,

e Macronema, Trichoptera) . Os

dois animais representam termos

finais bastante diferenciados de

duas progressões evolucionárias

etológicas-morfológicas . A sua

contemplação comparativa aqui

efetuada tem sua justificação peia

maneira, pela qual êstes animais

com os mesmos princípios, mas

com técnica bem diversa, acharam

como fonte de alimento o “Nanno-

Tripton” orgânico dos igarapés

amazônicos.

SUMMARY

Building-behaviour and way of

feeding of two aquatic insect-larvae

( Asthenopus , Ephemeroptera, an:l

Macronema, Trichoptera) are dealt

with. Both are the strongly modi-

fied final members of two ethologi-

cal-morphological lines of evolu-

tion. The comparative considera-

tion of them, which is performed

in this paper, is justified by the

fact that both have made accessi-

ble the organic “nanno-tripton”

of the forest-creeks in the Amazon-

-region as a food-source in princi-

pally equal ways but the quite dif-

ferent technics.

REFERÊNCIAS BIBLIOGRÁFICAS

Despax, r., 1949, Ordre des Éphémérop-

tères, in Grassé, Traité de Zoologie,

9: 279-309, 19 figs. Masson & Cie.,

Paris.

Fric, A. & Vávra, V., 1901, Untersuchun-

gen über die Fauna der Gewàsssr

Bõhmens. V, Arch. naturw. Landes -

durchf. Bõhmen, 9, 3: 1-154.

Hartland-Rowe, T„ 1953, Feeding xne-

chanism of an Ephemeropteran

Nymph. Nature, 172 (4389) : 1109-

-1110, 1 Fig.

Hartland-Rowe, T., 1958, The biology

of a tropical mayfly Povilla adusta

Naves (Ephemeroptera Polymitar-

cidae) with special reference to

the lunar rhythm of emergence,

Rev. Zool. Bot. Afr., 58 (3/4) : 185-

-202, 4 Figs.

Needham, J. G., Traver, J. R. & Hsu,

Yin-Chi, 1935, The Biology of May-

flies, New York.

Réaumur, R„ 1734/42, Memoires pour

servir à Vhistoire des Insectes.

Paris.

Sattler, W., 1963, über den Kõcherbau,

die õkologie und Ethologie der

Larve und Puppe von Macronema

Pict. (Hydropsychidae) , ein ais

Larve sich von “Mikro-Drift”

emãhrendes Trichopter aus dem

Amazonasgebiet. Arch. HydrobioL,

59 (1) : 26-60, 24 Figs. 4 Taf.

Sattler, w. & Kracht, A., 1963, Drift-

fang einer Trichopterenlarve unter

Ausnutzung der Differenz von

Gesamtdruck und statischem

Druck des fliessenden Wassers.

Natuncissenschaften, 50: 362, 2

Figs.

Sattler, W„ über die Lebensweise, ins-

besondere das Bauverhalten, neo-

tropischer Eintagsfliegenlarven

(Ephemeroptera, Polymitarcidae)

14 Figs. (no prelo).

Wesenberg-Lund, C„ 1943, Biologie der

Süssicasserinsekten, 682 pp., 501

figs., 13 Taf., Berlin.

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 201-220 — 1967

ORIENTATION OF AMAZONIAN FISHES TO THE

EQUATORIAL SUN

HORST O SCHWASSMANN

Scripps Institution of Oceonography,

La Jolla, Califórnia, U.S.A.

CWith 8 text-figures)

Some of the most challenging

problems in modern biology are

concerned with the orientation of

animais in time and in space. A

great deal of research of a merely

descriptive nature is still needed in

this field, but some experimental

studies of the sensory mechanisms

involved in orientation have yield-

ed results as surprising as the dis-

covery of time-compensated sun-

-compass orientation in the honey

bee (Frisch, 1950), in birds (Kra-

mer, 1950), and in fish (Hasler,

Horrall, Wisby & Braemer, 1958).

Many fish are known to under-

take long distance migrations in

the ocean and some even home to

particular spawning sites. Exam-

ples are the many species of sal-

hionids, the eel, and the tainha

(Mugil brasiliensis) . While in the

salmon the clfactory sense appears

to play an important role in de-

tecting the home stream (Wisby

& Hasler, 1954) , and probably also

the spawning ground, olfactory

orientation can not explain ade-

quately the directed movements cf

fish in the ocean. Therefore, orien-

tation by visual means was consi-

dered to be a likely hypothesis, and

has been studied in field and labo-

ratory experiments since 1955 at

the Laboratory of Limnology, Wis-

consin, under guidance of Prof.

A. D. Hasler. Field experiments

showed that white bass ( Roccus

chrysops Raf.) oriented towards

the spawning ground significantiy

better when released under sunny

conditions than under a cloudy

sky. In addition, it was discovered

that centrarchid fish, which were

trained to swim into a compass di-

rection, depended on the sun

in maintaining this direction

throughout the day and that they

could allow for the sun’s daily mo-

vement (Hasler et al., 1958) .

All earlier experiments about

sun-orientation of vertebrate ani-

cm l

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10 11 12 13 14 15

202

Atas do Simpósio sôbre a Biota Amazônica

mais had been made in higher

northern latitudes where the sun’s

apparent daily movement around

the horizon (the sun’s azimuth

curve) is relatively uniform and

where a uniform rate of changing

the angle of orientation to the

sun’s azimuth (at 15 degrees per

hour) would allow the animal to

remain oriented into one compass

direction. Moreover, in contradic-

tion to an early theory about bird

navigation which emphasized the

importance of the sun’s changing

altitude (Matthews, 1955), seve-

ral experimental results seemedto

disprove an effect of the sun’s

height on the orientation of birds

(Hoffmann, 1954; Rawson &

Rawson, 1955; Kramer, 1955;

Schmidt-Koenig, 1961), and it

became customary to speak about

“sun-azimuth-orientation” . This

simplified concept of orientation to

the sun’s azimuth had to be re-

-examined after experiments by

Braemer (1959, 1960), and after

results with cichlids from the Ama-

zon at the equator (Hasler &

SCHWASSMANN, 1960) .

To illustrate one of the major

problems for sun-orientation in the

tropics, Fig. 1 shows the sun’s

movement from sunrise to sunset

at a place in the northern hemis-

phere (50°N) and at the equator

when the sun’s declination is 10°S

(22 March and 19 October) . The

hourly intervals in the azimuth

curve of the sun are rather uniform

at 50° N, but they are quite diffe-

rent at the equator where there is

little change in the sun’s azimuth

during morning and evening and a

more than 100° change during the

two hours around noon. If a sun-

compass animal compensated for

the sun’s azimuth movement at

a uniform rate of approximately

15°/hour, it could not be oriented

into a compass direction at the

equator . In adition, the direc-

tion of the sun’s azimuth move-

ment reverses itself twice during

the year in the tropics. Near the

equator, it changes from clock-

wise in late March to counter-

clockwise, and becomes again

clockwise in late September. Sun-

compass animais which live in the

tropics must be able to allow for

the sun’s movement in the two

different directions at different

times of the year.

Subsequent experiments with

fish demonstrated that the sun’s

altitude was of importance and

that it influenced the change of

the conditioned angle to the sun’s

azimuth (Braemer & Schwas-

SMANN, 1963; SCHWASSMANN &

Hasler, 1964), confirming and ex-

tending the earlier results by Bra-

emer (1959). It could also be

shown how the rate of change of

the sun’s altitude determined the

rate of change of the trained ho-

rizontal orientation angle in young

Volume 3 (Limnologia)

203

centrarchid fish at first exposure

to the sun (Schwassmann & Has-

ler, 1964). The duration of day-

light which changes considerably

throughout the year at higher la-

titudes was found to influence the

rate of change of the trained an-

gle to the sun in centrarchid fish

' (Schwassmann & Braemer, 1961).

This factor can be of no impor-

tance near the equator because the

day length here is a constant

twelve hours all year.

Sun-compass behavior in fish de-

pends on a circadian clock mecha-

nism, continuously synchronized

with the natural day by sunrise

and sunset which can be replaced

in experiments by the onset and

termination of artificial light.

Shifting the “on” and “off” times

in the light cycle results in a pre-

dictable shift of the compass direc-

tion to which the fish had been

trained (Braemer, 1959) . In cons-

tant artificial light, the orientation

rhythm was found to continue, but

the period length was now slightly

different from 24 hours (Schwass-

mann, 1960).

The present paper describes ex-

periments on sun-compass orien-

tation of fish from the Amazon re-

gion which illustrate and partial-

ly answer some of the problems in

the tropics.

METHODS

The apparatus for training and

testing fish in a metal tank of 1.60

meter diameter with slanted walls

which is filled with water and

which prevents the fish inside from

seeing any landmarks on the hori-

Pig- 1 — Hourly positional changes of the sun at 10° S ãeclination for a latitude

of 50° N in A, aiid at the equator in B. An observer, stationed in the center of

the half-circles would see the zenith (center of the sky) ãirectly above and the

horizon represented as the periphery. The sun moves across the sky at a constant

speed of 15°/hour. At a low inclination of the sun’s arc 'A), the azimuthal po-

sition of the sun changes at a fairly uniform rate. At the same time of year.

the rate of change of the sun’s horizontal projectory (azimuthi is highly alinear

at the equator ( Bi because of the high inclination of the sun’s arc.

cm l

SciELO

10 11 12 13 14 15

204

Atas do Simpósio sôbre a Biota Amazônica

zon (Fig. 2). Sixteen metal boxes

are arranged in a circle inside the

tank, their openings pointing out-

wards. They are covered by a cir-

cular plate and cannot be seen by

the fish upon release from the cen-

ter where it is held captive in a

cylinder of transparent plastic.

Releasing the fish is done remotely

by a lever underneath which

causes the plastic center cage to

recess into the well. Observation of

the fish is accomplished by two

observers through four concentri-

cally mounted periscopes. In order

to prevent orientation to marks

within the tank, the latter is rotat-

ed between trials. For training,

only one of the sixteen boxes is

open and always points into the

same compass direction. Training

is repeated daily at the same time

fcr usually 10 to 20 minutes, un-

til the fish has apparently learned,

to relate the position of the one

open box, in which it can hide,

with the sun’s position at this time

of day. During later testing all six-

teen boxes are open and tests are

conducted at áifferent times of the

day. Every test consists of at least

five trials and the observers record

the exact place at which the fish

swims over the margin of the co-

ver plate before entering a box.

Some experiments at Belém were

made utilizing a large mirror to

reflect the sun into the tank,

whereas the real sun was blocked

from the view of the fish by a large

sunshade (Fig. 2) .

The fish species used were the

following cichlids: Cichlaurus se-

verus s. Heckel, Crenicichla saxa -

tilis L., Varn amphiacanthoides He-

ckel, and Aequidens portalegrensis

Hensel. In addition, experiments

are reported with Anableps micro-

lepis Mueller & Troschel, and the

North American centrarchid Lepo-

mis cyanellus Rafinesque. All fish

were immature and between five

and eight centimeters long.

RESULTS

1) Orientation to the equatorial

sun — Once a fish has been traim

ed for a few weeks to swim at a

certain angle to the sun, and al-

ways during the same ten minutes

every morning, it is then tested at

different times of day. Two differ-

ent modes in the behavior have

been found. The great majority of

t.ained fish will swim into the

same compass direction. Because

of the daily movement of the sun,

these fish alter the angle of swim-

ming in relation to the sun’s azi-

muth position continuously. This

behavior is called time-compensat-

ed sun-compass orientation . Some-

times a fish will swim at the

same angle to the sun, to which

it had been trained, also at other

times of the day; it will not allow

for the sun’s movement with time.

Such “azimuth constancy” is rare

Volume 3 (Limnologia)

205

Fig. 2 — Training and testing apparatus shown in testing condition.

The fish is held captive inside the plastic cage in the center of

the water-filled tank. The release mechanism (R) causes the centei

cage to recede into the well, liberating the fish which can swim

into any ãirection and will seek cover in one of sixteen open boxes.

Two of four periscopes (Pi for observation are shown. The turn-

-table icith the tank is rotated after every trial. For some expe-

riments the sun iças blocked by a shade (St and reflected into

the tank by a mirror (M).

under the real sun, but is usually

found when the real sun is replac-

ed by an electric light bulb.

For the first behavior, the com-

monly observed sun-compass ori-

entation, it remains to be shown

that the fish actually utilize the

position of the sun only, and that

their compass constancy is not

caused by some other factor un-

known to us. In order tc demons^

trate if the sun was the important

externai reference, a large mirror

was used in 1962 at Belém. As a re-

p

206

Atas do Simpósio sôbre a Biota Amazônica

sult, the orientation of all the ci-

chlids used in these experiments

was 180° reversed (Fig. 3). The an-

gle between mean direction of the

scores and the real sun in A is the

same as the one between mean di-

rection and reflected sun in B. The

mirror worked so effectively that it

was employed to test the influen-

ce of the sun’s altitude on the ori-

entation of these fish. Changing

the apparent altitude of the sun

could easily be accomplished by

tilting the mirror in its horizontal

axis. The results have been report-

ed in detail elsewhere (Braemer &

SCHWASSMANN, 1963).

Having established the sun’s po-

sition as the effective externai re-

ference in the orientation behavior

of the fish, justifies recording cf

individual test scores as angles to

the right or left of the sun and the

data can be presented in this man-

ner with the sun’s position kept

stationary and indicated as a strai-

ght line (Figs. 4, 6, 7) . A compass

direction is represented in these

graphs as a curve d line which is

computed from the sun’s azimuth

curve during the time of the expe-

riments. If a fish would swim ac-

curately into this compass direc-

tion, its scores should follow this

latter curve.

Usually, the orientation of one

trained fish is not very accurate;

the mean direction of a test often

deviates from the compass direc-

tion and the scatter around the

mean is great. However, when a

great number of scores from tests

Fig. 3 — A mirror experiment. A: directioiial scores of five cichlids under

the real sun. B: scores under the reflected sun. Immediately after the tests

in A, the view of the sun was blocked by a shade (S) but the sun was re-

flected by the mirror ( M ) into the tank. All fish sxoim at approximately the

same angle to the mirror image of the sun in B, as they swam to the real

sun in A, but reversed in compass direction by 180°. The experiment de-

monstrates that the sun is the only externai reference point in the orien-

tation of these fish. Data by Braemer & Schwassmann (1963)

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Volume 3 (Limnologia)

207

LOCAL MERIDIAN TIME

Fig. 4 — Sun-compass orientation of six cichlid fish at the equator during June

and early July 1962. The daily pattern of angular change over the entire day

to the sun’s azimuth can be seen. All scores of the six fish falling into each

hourly interval were averaged, and the mean was plotted (circles), with its

standard deviation ( vertical bars), as angle to the right or left of the sun’s

azimuth position (straight horizontal Une). The procedure is examplified for

four of the ten means (scatter diagrams showing all scores and the sun’s position

at this time). The curved Une indicatéS how a compass direction changes in

relation to the sun’s azimuth with time of day. If the fish allowed precisely for

the sun’s azimuth movement, their recordeá means should follow this Une

Data computed from 402 scores. From experiments

■ by Braemer and Schwassmann (1963).

of several fish is averaged, the com-

bined results show a good fit to

the theoretical curve. This is shown

in Fig. 4 where a total of 402

scores of six cichlid fish was used.

These fish were tested throughout

the day from 31.5. to 7-7-1962 at

Belém. All test scores falling into

each hourly interval were pooled

and the common mean with its

standard deviation is indicated.

The rate of angular change to the

sun is small during morning and

evening hours but is great during

the two hours around noon. Si-

milar data have been presented by

cm 1

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10 11 12 13 14 15

208

Atas do Simpósio sôbre a Biota Amazônica

SCHWASSMANN & HASLER (1964).

Very few experiments have been

done at the equator during the

time of the equinoxes when the

sun’s noon position approaches the

zenith (Hasler & Schwassmann,

1960); and it was found that the

fish did not orient as well under a

very high sun.

2) Innate and learned behavior

in the sun-ccmpass of fish — An-

other experiment in collaboration

with Braemer in Wisconsin du-

ring 1958 yielded results of far-

reaching significane (Braemer,

Braemer & Schwassmann in

prep.). Green sunfish and Portcich-

lids were reared from the egg in

artificial light for several months

until they had reached a size suita-

ble for experiments on sun-orien-

tation. These fish never experienc-

ed any natural daylight, but their

regime of artificial lighting was

continually adjusted to the chang-

ing times of sunrise and sunset

at 43° N. During early September,

the fish were trained at local noon

in a darkened rcom to swim to-

wards an electric light bulb, simu-

lating the sun. They were tested

subsequently out-of-doors under

the sun in the morning and after-

noon. In these tests, they compen-

sated for the movement of the sun

correctly according to season and

latitude, although they had never

seen the sun, or its apparent daily

movement, previously (Fig. 5).

All green sunfish swam south

which corresponds to the sun’s po-

sition at noon, the time of previous

training towards the light (Fig. 5,

A„-A-). The behavior of the equal-

ly treated cichlids was different

from that of the North American

sunfish. At least the diagram Bi

shows a bimodal distribution. A

few scores point towards the sun,

indicating that the fish had not

changed the trained angle. A con-

centration of scores in the Southern

sector correspcnds to the behavior

of the sunfish. In addition, many

scores fali into the northern sec-

tor. A bimodality seems also indi-

cated in diagram B_. from the after-

noon test but the two modes are

not clearly separated, possibly ob-

scured by some “constant-sun-an-

gle” scores towards the sun.

The orientation behavior of the

cichlids can be analyzed in the fol-

lowing way: In the northern tem-

perate zone, the sun moves in a

clockwise direction through the

Southern part of the sky, its posi-

tion at ncon is South. Sun-compass

fish, like the Lepomis i compensate

for this movement by changing

the angle of swimming to the sun

in a counter-clockwise manner. In

the Southern hemisphere, the di-

recticn of the sun’s movement, as

well as that of the compensating

angular change of compass fish to

the sun, are the reverse. If the mo-

vement of the sun were to be com-

Volume 3 (Limnologia)

209

pensated for in the “wrong” direc- ge had the same sign, the change

tion, if sun motion and the in orientation angle of the fish

fish’s compensating angular chan- would be added to, instead of sub-

Fig. 5 — Demonstration of the innateness of sun-

compass behavior. The orientation behavior of six

North- American sunfish is shown on the left (scatter

diagrams A n — AJ and contrasted with the behavior

of six equálly tredteã tropical cichlids on the right (B t .

— B.J. A tl , B tl : scores at the training time under thè

electric light; A v B 1 : orientation scores at first exposure

to the sun, afternoon and morning respectively ; A„.

B.,: second tests under the sun, morning and afternoon

respectively. The mean directions from the control

tests under the electric light are indicated as solid

arrows in the four lower diagrams. In B 1 and B, the

direction to be expected for a compensation of the

sun’s movement in the "wrong” direction is marked by

the open arrow. Data from experiments by Braemer

and Schwassmann.

M — 37 121

cm 1

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10 11 12 13 14 15 16

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210

Atas do Simpósio sobre a Biota Amazônica

tracted from, the amount which

the sun had moved around the ho-

rizon in azimuth. In this case, the

compass direction which the fish

indicates would be continually

changing. The cichlids apparently

also compensate for the movement

of the sun, otherwise all scores

should point towards the sun, but

they change the orientation angle

to the sun in both directions, clock-

wise as well as counter-clockwi-

se. The compass directions, are in-

dicated in Bi and Bj, and the re-

sults seem to conform to the hy-

pothesis outlined above.

The results are evidence that

sun-compass orientation in fish is

basically an inherited behavior

pattern, requiring no learning of

the sun’s movement. In addition,

the apparent necessity for tropical

cichlids to learn in which direction

the sun is moving seems of biolo-

gical significance. Later experi-

ments have confirmed the innate-

ness of sun-compass behavior in

the green sunfish (Schwassmann

& Hasler, 1964). Experiments

which illustrate the “two-direction

ability” of cichlids are reported in

the following pages.

The ability of cichlid fish from

the Amazcn to learn to accomodate

their orientation behavior to a re-

versed sun movement was demon-

strated by transporting them, after

training and testing at Belém, to

Madison, Wisconsin (43° N) during

1961. The orientation of two fish

at Belém in late May is shown in

Fig. 6 A, where the sun’s move-

ment was counter-clockwise and

the fish’s angular change occured

in a clockwise manner. In early

June the two fish were tested at

43° N (Fig. 6, B) where they con-

tinued to change their angle to the

sun as they did at the equator pre-

viously. After five days exposure to

the sun out-of-doors, and one 15

minute period cf re-training in the

morning to an electric light in-

doors, one of the two fish appeared

to have learned and accommodat-

ed for the locally correct direction

of the sun’s movement (Fig. 6, C) .

The other fish lost its oriented be-

havior during the five days of out-

door exposure and a brief re-train-

ing was ineffective. Confirmation

of these results was obtained by

data from two more cichlids which

had been brought from Belém to

43° N where they were trained to

swim towards an electric light at

noon. In the first tests under the

real sun of 43° N they scored like

the two cichlids in Fig. 6, B, but

after two weeks of partial exposu-

re to the local sun one had com-

pletely reversed the direction

whereas the other now seemed un-

decided and showed scores accord-

ing to the two different modes of

compensating angular change, si-

milar to the inexperienced cichlids

in Fig. 5, B. These and further data

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Volume 3 (Limnologia)

211

Fig. 6 — Data which demonstrate the ability of

cichlids to accomodate their compass orientation to

a sun movement in the reverse direction. The uiean

directions with standard deviations are plotted as

in Fig. 4 (filled and open circles ]or the two dif-

ferent fish) and each was computed from a mi-

nimum of five scores. A: pattern of angular change

to the counter-clockwise movement of the sun at

Belém in May 1961. B: the orientation o f the same

fish after transport to 43° N in early June under a

clockwise sun movement. C: the pattern of angular

change to the clockwise moving sun is “locally cor-

rect” in one of the two fish after five days exposure

to the sun. The solid curve indicates a compass di-

rection under the local sun movement, the dasheã

curves in B and C indicate the pattern of angular

change to the sun at Belém.

were reported earlier (Schwass- ported above were made at a time

mann, 1962). The experiments re- when the sun’s altitude curves

212

Atas do Simpósio sobre a Biota Amazônica

were quite similar at both loca-

tions; at least the noon position of

the sun was of the same height.

Since the day at 43° N was consi-

derably longer than 12 hours, the

fish were kept in an artificial light

cycle with 12 hours, light, except

for the day of exposure to the local

sun.

To test the two-direction concept

in the sun-orientation of cichlids

further, and to compare it with the

apparently hereditarily fixed sin-

gle direction of compensation in

centrarchids, experiments were de-

signed which enabled training of

fish to a sun apparently moving

in the opposite direction. The ex-

periment did not require transport-

ing the fish over long distances

and also left the daily sun arc

unaltered except for the reversal

of direction. This was accomplished

by mounting a tank on a turn-ta-

ble which had fastened to its un-

derside an excentrically mounted

ring gear. This gear was driven by

a constant speed motor with reduc-

tion box and final pinion which, as

a unit, remained stationary in azi-

muth but was sliding in and out

radially because of the ring-gears

excentricity. The resulting rotation

was in the same direction as the

sun’s movement, but at exactly

twice its azimuth velocity (Fig. 7,

B). Sufficient reference marks in-

side the turning tank, in addition

to the usual single training box,

were provided so that the fish in-

side had opportunity to relate their

successive positions with the sun.

Fig. 7, A shows the orientation of

two Cichlaurus severus cichlids

which were brought from Belém to

Madison, Wisconsin. They had

been kept in natural daylight and

were trained during early Septem-

ber 1962 to swim towards the sun

between 0700 and 0800 hours. They

compensated locally correct for the

sun’s movement (Fig. 7, A, 1-2).

After five sunny (and more clou-

dy) days inside the azimuth-rever-

sal apparatus, they were tested

again and had now reversed the

direction in which they changed

the orientation angle to the sun

(Fig 7, A, 1-3). They allowed for

the sun’s movement as it was at

this time of year (autumnal equi-

nox) at the same latitude in the

Southern hemisphere.

3) Sun-compass orientation of

fish in nature — Few experiments

with fish have been made which

investigated if sun - orientation

might be involved in movements to

a spawning ground, or towards

“home”, after experimental displa-

cement, during a certain phase of

active migration. Simple displace-

ment and release at a distant pla-

ce might not always yield conclu-

sive data, since additional factors

could provide orientational cues,

like odors, landmarks, etc. Better

directed orientation under a sunny

Volume 3 (Limnologia)

213

B

LOCAL M ER1 Dl AN TIME

Eig. 7 — Experimental reversal o) the direction of the sun’s movement at 43° N

latitude. The principie of the azimuth-reversal apparatus is shown schematically

V} At 0800 hours the open training box inside the tank (T) is in Une with

the sun’s azimuth. At 1000 and at 1200 hours, since the tank has been rotated

at twice the sun’s azimuth velocity, the open box has traveleã tivice as much

as the azimuth of the sun, simulating a sun movement in the opposite direction.

In A is shown the orientation behavior of tico cichlids from the Amazon, after

training at 0800 hours (tests 1). They changed the orientation angle correctly

for the clockioise sun movement (1. to 2.J. After five sunny days of treatment

in the azimuth-reversal apparatus, they had reversed the direction of angular

change to the sun and allowed for a movement of the sun as it tcas correct for

the Southern hemisphere <1. to 3.).

sky than under cloudy conditions

is an indication for the sun’s im-

portance in guiding the fish (Has-

ler et. al., 1958; Winn, Salmon,

& Roberts, 1964). If the direction

°f “homing” after release is shift-

e d by the amount predicted by a

phase-shift of the fish’s time sense

(conditioning the fish in a delayed

or advanced artificial light cycle

for several days), sun-orientation

can be assumed to be the orienting

hiechanism (Winn et. al., 1964).

ff the fish are sufficiently small,

they can be tested in a circular

tank where possible environmental

cues other than the sun seem to

be eliminated. Groot (1965) used

this method to investigate the

orientation of sockeye smolt during

their seaward migration and the

data indicate that the sun plays at

least a certain role in the orien-

tation of these salmonids.

Experiments in the field with

fish, of which some natural ten-

dency to swim in a certain compass

direction is known, are promising.

They have the great advantage

that no directional training is ne-

cm 1

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10 11 12 13 14 15

214

Atas do Simpósio sôbre a Biota Amazônica

cessary. One experiment of this

kind was done in 1964 at Salinas,

Pará, with Anableps microlepis.

Previous studies on a large popu-

lation of these fish near Salinas

had shown that they form schools,

the size and compactness of

which depends on the age and sex

of the fish. Adult females were ob-

served in lcose groups of from two

to ten, the smaller males and

younger females in groups of five

to twenty. These schools of large

and médium sized Anableps

swam along the beach in open

water and in bays and river out-

lets. They were never found in very

deep water but stayed close to

shore. Most striking was their

change in behavior during the

later part of every rising tide, day

or night, when these fish literally

stranded themselves on the beach

with every incoming wave, often

being left on the sand by the rec-

eding water . A similar behavior of

moving close to shore with every

rising tide was thought to be cor-

related with increased feeding ac-

tivity, since many shore insects

are trapped by the rising water.

Studies of the Salinas population

demonstrated an obvious purpose

of the cyclic behavior . During

March of 1962, at the time of the

high tides of the equinoctial

syzygies, many hundreds of the

fish entered in this manner

through an 80 meter long channel

into a large brackish water lagoon.

With every rising tide, day or

night, the fish concentrated in

large numbers at the channel

entrance. At about the time of

highest water levei, the fish revers-

ed this movement and had left the

lagoon before the channel had be-

come dry. Inside the lagoon, many

large schools of often more than a

hundred newly born and up to se-

ven centimeter long Anableps were

found. The small fish did not leave

the lagoon until a considerably

later date. The lagoon obviously

served as breeding ground for this

Anableps population. Later obser-

vations were made during April

1964, when the tidal change in wa-

ter levei was insufficient to flood

the channel leading into the la-

gocn. Now only a few Anableps,

seven to ten centimeters long, were

found inside, but all the larger

fish outside still showed the same

behavior of concentrating at the

channel mouth with every rising

tide.

These fish seemed ideally suited

for sun-orientation tests because of

their strong directional tendency

and also because of the known

outstanding performance of their

visual system, especially of the ae-

rial portion of the “amphibious”

eye (Schwassmann & Krugeh,

1965). The orientation tank was

placed on a high sand dune near

the lagoon so that the horizon was

«•o

Volume 3 (Limnologia)

215

occluded by the rim of the tank.

Since large Anableps could not be

accomodated in the apparatus, fi-

ve immature fish, eight to ten cen-

timeters in length, were captured

out of a larger school which dis-

played consistently strong swim-

ming in an E-N-E direction. This

was the generally observed tenden-

cy of the entire population corre-

sponding to the direction of chan-

nel and lagoon. Time of capture

was the 26-4-1964, 1730 hours, dur-

ing rising tide which had begun

around 1400 hours. After over-

-night storage in individual cover-

ed containers, the fish were tested

the following morning shortly be-

fore high tide levei, and again in

the late afternoon during the early

part of the next rising tide. Bad

weather prevented further testing

and there was from 50 to 70%

cloudcover during the tests. In

these trials all fish showed a

strong preference for the E — and

N-E sector (Fig. 8, A, B) . Three of

these fish could be tried again after

sunset and under complete cloud-

cover with beginning heavy rain

before it became completely dark.

They now displayed random scat-

tering in their orientation, al-

though it was still the time of ri-

sing tide (Fig. 8, C). Equally dis-

oriented behavior was noted in

three small Anableps from a dif-

ferent population inside a nearby

bay which were captured during

falling tide and tested immedia-

tely.

The results show that Anableps

can utilize the sun’s position as di-

rectional reference when other

means of orientation are excluded,

and that they are capable of time-

compensated sun-compass beha-

vior. When the sun was in the East

in the morning, they swam to-

wards it, whereas they swam away

from it in the late afternoon, thus

maintaining one compass direc-

tion. No orientation seemed possi-

ble without the presence of the sun

in the artificial environment of the

testing apparatus.

Fig. 8 — Sun-orientation of five Anableps at the equator. A: Scores during the

B: scores in the late afternoon, both tests under 50-70% cloudcover.

■ apparent random behavior after sunset and in heavy rain. The sun’s position

indicated in A and B; North is up. Each fish is indicated by a different symbol.

216

Atas do Simpósio sôbre a Biota Amazônica

DISCUSSION

The fish species used in the ex-

perimente are mostly non-migrato-

ry and usually inhabit small bo-

dies of water; they were chosen be-

cause of the easiness with which

they could be maintained in capti-

vity and trained to compass direc-

tions. That all the investigated spe-

cies were found to be capable of

time-compensated sun-orientation,

together with the evidence about

the innate nature of the basic pat-

tern to alter the angle of swimming

to the sun with time of day, makes

it appear likely that sun-orienta-

tion plays an important role in the

directional movements of fish in

nature. Of further significance

should be the considerable accura-

cy of this compass orientation

which is noted when many data of

several fish are averaged, as com-

pared to the performance of an in-

dividual fish. Most species that un-

dertake long distance migrations

are schooling and usually migrate

together in large numbers.

Major difficulties were envisaged

in sun-orientation for animais li-

ving in the tropics, where not only

the sun’s movement occurs along

a very steep arc but where also the

direction of movement reverses it-

self twice during the year. It could

be demonstrated that South Ame-

rican cichlids can compensate for

the sun’s movement in either di-

rection, and that they are able to

learn to accomodate for a sun mo-

vement in the opposite direction

within a few days.

Sun-compass orientation in fish

is the expression of an endogenous

circadian rhythm. The poor accu-

racy, usually apparent in the re-

corded directional performance of

trained fish, is certainly not a true

measure of the precision of the in-

volved time sense. Another species

of fish from the Amazon, the gym-

notid Gymnorhamphichthys hy-

postomus Ellis, exhibits a high de-

gree of precision of its endogenous

rhythm when a different parame-

ter, the daily onset of activity, is

used for its measurement (Liss-

MANN & SCHWASSMANN, 1965 ).

It is not known how important

the sun-compass might be for the

orientation of fish in nature. Its

usefulness seems to be limited to

times of day with sunshine.

Certainly, other means of orienta-

tion must also be important, since

many fish migrate in an apparent-

ly oriented manner also at night.

That the sun can become an im-

portant reference for orientation

when other directional cues are

excluded, was shown by the expe-

rimente with Anábleps. The beha-

vior of Anábleps is of additional in-

terest, because it not only resem-

bles the peculiar spawning beha-

vior of the Califórnia grunion

(Leuresthes tenuis Ayres), but the

Volume 3 (Limnologia)

217

urge to return to the original place

of birth (at least in the observed

population) is reminiscent of the

homing behavior of salmon. It

might well be possible that similar

principies of early imprinting and

orientation are involved.

Acknowledgements — Most of the

experiments reported here were part

of the author’s thesis work on sun-

orientation of fishes, conducted under

the guidance of Prof. A. D. Hasler at

the Laboratory of Limnology, Univer-

sity of Wisconsin, and supported by

the National Science Foundation

(G-3339) and the Office of Naval

Research (NR-301-903) . The orien-

tation studies on Anableps were made

while the author was a post-doctoral

fellow of the Public Health Service

and affiliated with the Department of

Anatomy, University of Califórnia, Los

Angeles. Research support was obtain-

ed from the Office of Naval Research

(NR-301-790) and the National Science

Foundation (GB-2796) . The Museu

Goeldi, Belém, provided necessary fa-

cilities and Services for the experi-

ments near the equator. The azimuth-

-reversal apparatus was built by Mr. E.

Hanson of the Department of Zoology,

University of Wisconsin. The data

shown in Figs. 3, 4, and 5 were obtain-

ed in collaboration with the late Dr.

Wolfgang Braemer.

SUMMARY

Fish can orient into compass di-

rections by using the sun’s posi-

tion as externai reference and by

making allowance for its daily mo-

vement. Reflecting the sun from a

large mirror, it could be demons-

trated that the sun was the only

environmental reference point in

this orientation. Under the very

steep sun arc at the equator, cor-

related with a greatly alinear rate

of the sun’s movement around the

horizon, the compass-orientation

of cichlids from the Amazon is as

precise as the sun-compass of fish

at higher latitudes. Very little

change of the orientation angle to

the sun’s azimuth is observed du-

ring morning and evening hours;

practically all angular change oc-

curs during the two hours around

noon.

Raising centrarchid and cichlid

fish from the egg in conditions of

artificial light, gave evidence that

the basic feature of sun-compass

behavior, the tendency to alter the

angle of swimming to the sun with

time of day, must be considered an

innate behavior pattern. In the

N or th- American centrarchids also

the direction in which this angu-

lar change to the sun occurs ap-

pears hereditarily fixed, whereas

the tropical cichlids need to learn

the direction in which the sun

moves around the horizon. About

five days of exposure to a sun

movement, in a direction opposite

to that which the cichlids had

learned previously, suffices to

cause the fish to reverse the

direction of changing its orienta-

tion angle to the sun.

cm 1

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218

Atas do Simpósio sobre a Biota Amazônica

Anableps from a population

which displayed strong directional

swimming during rising tide were

found to orient to the sun and to

allow for its daily movement when

they were deprived of other xneans

of orientation.

SUMÁRIO

Os peixes são capazes de se ori-

entarem no espaço usando como

referência a posição do sol, toman-

do em consideração o seu movi-

mento diurno (“sun-compass ori-

entation”). Com a reflexão do sol,

usando um grande espelho, foi pos-

sível demonstrar que o sol é o úni-

co ponto de referência externa usa-

do nesta orientação.

Em condições equatoriais onde a

inclinação do sol aproxima o ze-

nite e, em conseqüência, o movi-

mento solar segue uma trajetória

horizontal não linear, a orientação

dos ciclideos amazônicos é tão pre-

cisa como a dos peixes em latitu-

des maiores. Durante a manhã e a

tarde, os peixes quase não mudam

o ângulo de orientação ao azimu-

te solar, mas durante as duas ho-

ras antes e depois do meio-dia a

mudança angular é considerável.

Baseado no fato de que peixes

(Centrarchidae e Cichlidae) t cria-

dos em laboratório sob luz artifi-

cial desde o ôvo, têm a capacidade

de se orientarem ao sol, levando

em consideração o movimento so-

lar, concluímos que êste tipo de

orientação é inato. Nos Centrar-

chidae norte-americanos, a direção

em que a mudança do ângulo ao

sol se efetua, também parece ser

hereditária, enquanto que nos ci-

clideos tropicais os peixes precisam

aprender em que direção o sol mo-

ve ao redor do horizonte. Expon-

do os ciclideos ao movimento so-

lar oposto ao prèviamente aprendi-

do por cêrca de cinco dias é sufi-

ciente para que êles revertam a di-

reção em que êles alteram o ângulo

de compensação.

Os tralhotos de uma população

que demonstraram marcada ten-

dência em nadar numa certa dire-

ção durante a maré enchente são

também capazes de se orientar ao

sol levando em consideração o seu

movimento, quando desprovidos de

outros meios de orientação.

REFERENCES

Braemer, W., 1959, Versuche zu der im

Richtungsgehen der Fische enthal-

tenen Zeitschàtzung. Verh. Deut.

Zool. Ges., 1959: 276-288.

Braemer, W., 1960, A criticai review of

the sun-azimuth hypothesis. Cold

Spring Harbor Symp., 25: 413-427.

Braemer, w. & Schwassmann, H. O.,

1963, Vom Rhythmus der Sonneno-

rientierung am Aquator bei Fis-

chen. Ergebn. Biol., 26: 182-201.

Volume 3 (Limnologia)

219

Braemer, w., Braemer, H. & Schwass-

mann, H. O., Z. Tierpsychol. in prep.

Frisch, K., 1950, Die Sonne ais Korapass

im Leben der Bienen. Experientia,

6 : 210 - 221 .

Groot, c„ 1965, On the orientation of

young sockeye salmon (Oncorhyn-

chus nerka) during their seaward

migration out of lakes. Behaviour,

Suppl. 13: 1-198.

Hasler, A. D., Horrall, R. M., Wisby,

W. J. & Braemer, W., 1958, Sun

orientation and homing in fishes.

Limnol. Oceanogr., 3: 353-361.

Hasler, A. D. & Schwassmann, H. O.,

1960, Sun-orientation of fish at

different latitudes. Cold Spring

Harbor Symp., 25: 429-441.

Hoffmann, k., 1954, Versuche zu der

im Richtungsfinden der Vogei

enthaltenen Zeitschátzung. Z. Tier-

psychol., 11: 453-475.

Kramer, G., 1950, Orientierte Zugakti-

vitàt gekàfigter Singvõgel, Natur-

wiss., 37: 188.

Kramer, G., 1955, Ein weiterer Versuch,

die Orientierung von Brieftauben

durch jahreszeitliche Anderung der

Sonnenhõhe zu beeinflussen. Glei-

chzeitig eine Kritik zur Theorie des

Versuches. J. Ornithol., 96: 173-185.

Lissmann, H. W. & Schwassmann, H.

O., 1965, Activity rhythm of an

electric fish, Gymnorhamphichthys

hypostomus. Z. vergl. Physiol., 51:

153-171.

Matthews, G. V. T., 1955, Bird Naviga-

tion, 141 pp., Cambridge University

Press, Cambridge.

Rawson, K. S. & Rawson, a. M., 1955,

The orientation of homing pigeons

in relation to sun declination. J.

Ornithol., 96: 168-172.

Schmidt-Koenig, K„ 1961, Die Sonne

ais Kompass im Heimorientierungs-

System der Brieftauben. Z. Tier-

psychol., 18: 221-244.

Schwassmann, H. O., 1960, Environ-

mental cues in the orientation

rhythm of fish. Cold Spring Harbor

Symp., 25: 443-449.

Schwassmann, H. O., 1962, Experiments

on sun orientation in some fresh-

water fish, Thesis, Univ. Wiscon-

sin, Jan. 1962: 153 pp.

Schwassmann, H. O. & Braemer, W.,

1961, The effect of experimentally

changed photoperiod on the sun-

-orientation rhythm of fish. Phy-

siol. Zool. 34: 273-286.

Schwassmann, H. O. & Hasler, A. D„

1964, The role of the sun’s altitude

in sun orientation of fish. Physiol.

Zool, 37: 163-178.

Schwassmann, H. O. & Kruger, L., 1965,

Experimental analysis of the visual

system of the four-eyed fish, Ana-

bleps microlepis . Vision Res., 5:

269-281.

Winn, H. E„ Salmon, M. & Roberts, N.,

1964, Sun-compass orientation by

parrot fishes. Z. Tierpsychol., 21:

798-812.

Wisby, W. J. & Hasler, A. D., 1954,

Effect of olfactory occlusion on

migrating silver salmon (O. kisut-

ch). J. Fish. Res. Bd. Canada, 11:

472-478.

Atas do Simpósio sôbre a Biota Amazônica

Vol. 3 (Limnologia): 221-226 — 1967

SÔBRE O BALANÇO METABÓLICO DE IÔNIOS

INORGÂNICOS DA ÁREA DO SISTEMA

DO RIO NEGRO

HARALD UNGEMACH

Hydrobiologische der Max-Planck-Gesellschaft, Plõn, Alemanha e Instituto

Nacional de Pesquisas da Amazônia, Manaus, Amazonas

O abastecimento de elementos

nutritivos inorgânicos para os or-

ganismos terrestres vem primeira-

mente do solo. Além disso têm im-

portância a alimentação através de

precipitações. Em certas regiões te-

mos o fenômeno do abastecimento

com elementos nutritivos transpor-

tados pelo vento. Além disso é ne-

cessário a indicação do abasteci-

mento particular de compostos ni-

trogênicos formados pela atividade

microbiológica utilizando nitrogê-

nio atmosférico. O cálculo quanti-

tativo dêstes abastecimentos natu-

ralmente é difícil. Todavia, o ba-

lanço dos elementos nutritivos é

de alto interêsse.

Um fator importante no balan-

ço dos elementos nutritivos é a per-

da dêsses elementos por lixiviação

em uma dada região. Em parte ês-

tes elementos alcançam camadas

inferiores do solo onde formam

compostos insolúveis não tomando

mais parte na circulação biogêni-

ca dos elementos nutritivos. Outra

parte é carreada pelas águas cor-

rentes superficiais, enquanto que

provàvelmente a maior parte é ar-

rastada, com a água de percolação,

a água freática com a qual apare-

ce nas fontes e é eliminada, da re-

gião, com os córregos e rios. As

condições para êste transporte são

muito favoráveis na bacia do rio

Negro em virtude das elevadas pre-

cipitações (segundo o Atlas Pluvio-

métrico do Brasil de 1948, alcan-

çam 1.500 a 3.500 mm). Outros-

sim, existem vastas regiões com so-

los permeáveis; e há solos cujas

características físicas e químicas

apresentam pouco poder de absor-

ção de elementos nutritivos. Final-

mente, observando a bacia do rio

Negro, vê-se que é coberta por ex-

tensa rêde de afluentes, o que per-

mite uma conexão efetiva entre o

solo e a água. Os problemas dessa

comunicação entre o solo e água

foram pesquisados por Sioli e

cm 1

SciELO

10 11 12 13 14 15

222

Atas do Simpósio sôbre a Biota Amazônica

Klinge e são citados em diferentes

publicações básicas (Sioli, 1951,

1955 a, 1955 b, 1960 e 1964; Sioli

& Klinge, 1962).

Nesta coerência é que estamos

realizando pesquisas sôbre as quan-

tidades dos elementos de importân-

cia biológica que o rio Negro trans-

porta para fora de sua bacia. Re-

presentam êles as reservas em nu-

trimentos para o crescimento da

vegetação que são liberadas nos

solos daquela região progressiva-

mente.

Êsses trabalhos estão concentra-

dos na foz do rio, perto da cidade

de Manaus, onde realizamos regis-

tros ecográficos do perfil do rio e

determinações de velocidade da

correnteza. Com êsses dados foi-

-nos possível calcular sua vazão,

que em 13-4-66 atingiu a

27.000 m 3 /s.

Para pesquisas químicas coleta-

mos amostras de água pouco aci-

ma da cidade a fim de evitar a po-

luição.

Outrossim foram realizadas em

13-4-66 pesquisas químicas, cujos

resultados multiplicados pela va-

zão forneceram dados sôbre as

quantidades de elementos trans-

portados por segundo naquele dia,

como também a perda de elemen-

tos nutritivos inorgânicos no mes-

mo dia e por quilômetro quadrado

de sua bacia.

Em fevereiro, março e abril, em

oito diferentes dias, realizamos as

mesmas pesquisas; os dados quími-

cos indicaram apenas pequenas di-

ferenças das realizadas em 13-4-66,

não sendo por isso seus dados aqui

referidos. A amostra de 13-4 vai

mais pormenorizada porque nesta

data o rio apresentava uma vazão

aproximadamente média; por isso

mesmo os resultados terão talvez

um valor mais generalizado.

TABELA

Concentração

Transporte

em /ug/1

em kg/s

t/dia

g/dia/km-

N total

357

9,7

840

1 300

N (NH+)

15

0,40

35

54

N (NCT)

17

0,46

40

61

N Orgânico

325

8,8

765

1 180

P total

7,0

0,19

17

26

P (PO* - )

4,9

0,13

11

18

Fe total

370

10

860

1 300

Fe diss

280

7,6

660

1 000

Fe não diss.

90

2,4

200

300

Ca++

360

9,7

840

1 300

Mg ++

230

6,2

540

830

Volume 3 (Limnologia)

223

Das análises químicas evidenci-

ou-se inicialmente serem pequenas

as concentrações de substâncias,

principalmente de fósforo total e

fósforo de fosfatos que se apresen-

taram extremamente baixas; sen-

sivelmente baixas são também as

concentrações dos compostos de ni-

trogênio, o cálcio e o magnésio.

Digno de nota apresentou-se a

quantidade de feiTO, superando por

si a soma dos alcalino-terrosos, es-

tando êste fenômeno em correla-

ção com as características geoquí-

micas e edáficas da bacia que em

sua maior parte está pobre em cál-

cio. Da concentração total de fer-

ro somente 3 4 estão em dispersão

iônica, enquanto que 1/4 distribuí-

dos em forma não ionisada acham-

-se em suspensão, ou seja incorpo-

rados em outras substâncias.

A bacia do rio Negro apresenta

uma área de aproximadamente . . .

650.000 km- (determinação plani-

métrica usando-se o mapa do Brasil

de 1964, da escala 1: 5 000 000, edi-

tado pelo IBGE, Divisão de Carto-

grafia), e em 13-4-66 transportou

elementos na ordem de' 840 t de

nitrogênio total; 17 t de fósforo to-

tal e 1.380 t de alcalino-terrosos. O

fluxo dêsses elementos diàriamen-

te, por quilômetro quadrado é cal-

culado em : 1.300 g de nitrogênio

total; 26 g de fósforo total; 1.300 g

de ferro total e 2.100 g de cálcio e

magnésio.

Objetivamos continuar estas ob-

servações por um período mais pro-

longado, pelo menos um ciclo anual

inteiro, intensificando o trabalho

também por comparações entre ba-

cias de diferentes afluentes a se-

rem estudadas separadamente.

Os dados que apresentamos são

análises preliminares sôbre o ba-

lanço dos elementos inorgânicos

nutritivos da bacia do rio Negro,

pois os trabalhos estão agora ini-

ciados e não podemos por enquan-

to positivar o porque das condições

especiais dessa bacia.

SUMÁRIO

Pesquisas hidrográficas e quími-

cas estão sendo realizadas no rio

Negro, perto da cidade de Manaus,

para determinação das quantida-

des absolutas dos elementos da im-

portância biológica que êle trans-

porta. Estas pesquisas desenvol-

vem-se em duas partes distintas:

1) hidrográficas, para determina-

ção da velocidade da corrente e re-

gistro ecográfico da profundidade.

Êstes resultados permitirão cal-

cular a vazão do rio; 2) Químico-

analíticas, para determinação do

N, P e Fe sob vários aspectos par-

ticularmente Ca e Mg.

Em 13-4-66, as análises químicas

apresentaram os seguintes resulta-

dos para os vários aspectos quími-

cos do N, Fe e P e para os alcali-

nos-terrosos (Ca e Mg). Devemos

assinalar as diminutas concentra-

cm l

SciELO

10 11 12 13 14 15

224

Atas do Simpósio sôbre a Biota Amazônica

ções encontradas para os mesmos:

a concentração do ferro foi de

370 pg/1, é digna de atenção, su-

perando pouco a dos alcalinos-ter-

rosos, que se apresentaram com

360 ug/1 aproximadamente. O Fe

não dissolvido constituiu % da

concentração total dêsse elemento,

estando o restante em dispersão

iônica. A concentração do N, como

amónia, foi de 15 ug/1. Como ni-

tratos, 17 ug/1 e como N orgânico,

325 Hg/l.

O fósforo como fosfatos, estêve

presente em pequena quantidade

— 4,9 ug/1 — enquanto a concen-

tração total de P chegou à atingir

a quantidade de 7,0 ug/1.

Em 13-4-66, em uma das de-

terminações feitas, a vazão do rio

Negro foi determinada em

27 000 m ;i /s. O fluxo total diário

dos elementos, apresentou os se-

guintes valores: Nitrogênio total,

840 t (sendo 35 t como N de amó-

nia e 40 t sob a forma de nitratos) ;

Fósforo total, 17 t (sendo 11 t sob

a forma de fosfatos) ; Ferro total

(com 860 t) ; Cálcio (840 t) ;

Magnésio (com 540 t), respectiva-

mente.

Com relação à área da bacia do

rio Negro que é aproximadamente

de 650 000 km-, calculamos a par-

tir dos dados analíticos, referidos

acima, que a vazão diária de ele-

mentos químicos nesta bacia por

km- é de: nitrogênio total, 1 300 g;

nitrogênio orgânico, 1 . 180 g; fós-

foro total, 26 g; ferro total, 1.300 g;

cálcio, 1.300 g; magnésio 830 g.

SUMMARY

Hydrographical and Chemical

observations were carried out in Rio

Negi '0 near Manaus to determine

the amount of elements of biologi-

cal importance transported by the

river. The hydrographic work in-

cluded determinations of current

speed and echographic depth re-

cording. The data thus received

permitted the calculation of the

amount of water effluent out of the

basin of the Rio Negro. The Che-

mical determinations were extend-

ed to nitrogen, phosphorus, and

iron, each in different components,

and to calcium and magnesium.

On 13th of April 1966, for ins-

tance, the following data in a wa-

ter sample from Rio Negro were

found: 370 ug/1 of total iron, al-

most the concentration cf earth

alkalines present in 360 pg/1. Only

one fourth of the total iron is not

dissolved, three fourths are suspend-

ed. Ammonia-nitrogen was found

in a concentration of 15 gg/l. The

amount of nitrate-nitrogen is ... .

17 ug/1, and of organic nitrogen

325 ug/1- The sample contains

phosphate-phosphorus in a concen-

tration of 4,9 Hg/l, and total phos-

phorus in 7,0 ug/1.

The out-flow of the Rio Negro

basin on 13 ,h of April 1966 was cal-

culated to 27.000 m :i /s. The efflu-

Volume 3 (Limnologia)

225

ence of elements per day was as

follows: total nitrogen: 840 t, am-

monia-nitrogen : 35 1, nitrate-nitro-

gen: 40 t, total phosphorus: 17 t,

phosphate-phosphorus : 11 t, total

iron: 860 t, calcium: 840 t, mag-

nesium: 540 t.

The area of the basin of the Rio

Negro is approximately

650 000 km 2 . The effluent of ele-

ments per square-kilometre per day

was calculated as follows: total ni-

trogen: 1.300 g, organic nitrogen:

1.180 g, total phosphorus: 26 g, to-

tal iron 1.300 g, calcium: 1.300 g,

magnesium: 830 g.

BIBLIOGRAFIA

Conselho Nacional de Geografia, Divi-

são de Cartografia, 1964, Mapa da

República dos Estados Unidos do

Brasil, 1: 5 000 000.

Ministério da Agricultura, 1948, Atlas

pluviométrico do Brasil (1914-1938)

Sioli, H., 1951, Zum Alterungsprozess

von Fluessen und Flusstypen im

Amazonasgebiet. Arch. Hydrobiol.

45: 267-283.

Sioli, H., 1955, Beitraege zur regionalen

Limnologie des Amazonasgebietes.

III. Ueber einige Gewaesser des

oberen Rio-Negro-Gebietes. Arch.

Hydrobiol., 50: 1-32.

Sioli, H„ 1955, Die Bedeutung der Lim.

nologie fuer die Erforschung wenig

bekannter Grossraeume zu prak-

tischen Zwecken, anhand der Er-

fahrungen im Amazonasgebiet.

Forsch. u. Fortschr., 29: 73-84.

Sioli, H„ 1960, Estratificação radicular

numa caatinga baixa do alto Rio

Negro. Boi. Mus. Paraense Emílio

Goeldi, n. s., Botânica, 10: 1-9.

Sioli, H., 1964, General features of the

limnology of Amazônia. Verh. In-

ternai. Verein. Limnol., 15: 1053-

-1058.

Sioli, H. & Klinge, H., 1962, Solos, tipos

de vegetação e águas na Amazônia.

Boi. Mus. Paraense Emílio Goeldi,

n. s„ Avulsa, 1: 27-41.

COMPOSTO E IMPRESSO NAS

DO SERVIÇO GRAFICO DO

LUCAS, RIO DE JANEIRO, GB ■

OFICINAS

IBGE. —

- BRASIL.