International Society for the Study

and Conservation of Amphibians

(International Society of Batrachology)

SEAT

Laboratoire des Reptiles et Amphibiens, Muséum national d'Histoire naturelle,

25 rue Cuvier, 75005 Paris, France

BOARD FOR 1991

President: Raymond F. LAURENT (Tucumän, Argentina).

General Secretary: Alain DUois (Paris, France).

Treasurer: Dominique PAYEN (Paris, France).

Assistant Secretary, Europe: Günter GOLLMANN (Wien, Austria).

ant Treasurer, Europe: Annemarie OLER (Paris, France).

Assistant Secretary, outside Europe: David B. WAKkE (Berkeley, U.S.A.).

Assistant Treasurer, outside Europe: Janalee P. CALDWELL (Norman, U.S.A).

Other members of the Board: Jean-Louis FISCHER (Paris, France); David M. GREEN (Montreal,

Canada); Roy W. McDiarmip (Washington, U.S.A.); James I. MENZIES (Boroko, Papua New

Guinea}: Richard WassersuG (Halifax, Canada).

TARIFFS 1991

Subscription to

ISSCA Circalytes Alytes Total

Individuals

ISSCA direct members 60 FF 60 FF 200 FF 320 FF

ISSCA group or section members* 25 FF 60 FF 200 FF 285 FF

Non-members e - 220 FF 220 FF

Institutions

ISSCA direct members 120 FF 120 FF 400 FF 640 FF

ISSCA group or section members* 50 FF 120 FF 400 FF 570 FF

Non-members + — 440 FF 440 FF

* Members through a group or section of ISSCA (Société Batrachologique de France; Société

Lémanique de Batrachologie: Working Group on Oriental Amphibians)

Tariff for the inclusive Section or Group affiliation to ISSCA: 250 FF.

Tariff for individual subscription to the ISSCA Board Circular Letters: 200 FF.

MODES OF PAYMENT

_ In French Francs, by cheques payable to “ISSCA”, sent to our Treasurer (address above)

—_ In French Francs, by direct postal transfer to our postal account: “ISSCA”, Nr. 1 398 91 L, Paris.

— In U.S. Dollars: for further information, please write to: Janalee P. CALDWELL, Oklahoma Museum

of Natural History, University of Oklahoma, Norman, Oklahoma 73019, U.S.A.

Source : MNHN, Paris

AINTES

INTERNATIONAL JOURNAL OF BATRACHOLOGY

June 1991 Volume 9, N° 2

Alytes, 1991, 9 (2): 33-42. 33

Declining amphibian populations

— a global phenomenon ?

Findings and recommendations*

Amphibian populations are in decline in many parts of the world - in some

cases and in some areas to the point of extinction. Much of the decline is

attributable to obvious habitat destruction or modification. However, the

decline of populations even in protected areas indicates that more subtle

effects are involved. Where data are available, anthropogenic factors, such as

acid precipitation, pesticide release, agricultural practices, land-use changes,

and introductions of exotic species have been important in bringing about

these population changes. Although other organisms certainly are affected by

the same factors, amphibians are particularly sensitive bioindicators because

of their permeable skins, biphasic life history, pattem of embryonic develop-

ment, aspects of their population biology, and the complexity of their

interactions in communities and ecosystems. Several study programs should

be initiated, including carefully planned and integrated long-term studies of

populations and key communities, analyses of bibliographic and museum

data, and resurveys of previously studied populations. In the immediate future,

the findings of the workshop should be disseminated widely and the desir-

ability of a conference to deal with issues such as the use of amphibians in

biomonitoring, analyses of factors involved in declines, and future directions

in integrated approaches to the world-wide crisis in loss of biodiversity should

be explored. Careful evaluation should be given to proposals for new public

(such as a National Institute for the Environment) or private organizations that

would give attention to taxon-centered as well as more global monitoring and

study programs in the area of biodiversity.

Bibliothèque Centrale

QU NL

110038 6

* This is the title of a workshop, sponsored by the Board on Biology of the National Research Council of

the U.S.A., which was held at the Arnold and Mabel Beckman Center (Irvine, California, U.S.A.) on 19-20

February 1990.

** The conclusions, opinions, and recommendations contained in this article are those of the workshop

participants and do not necessarily reflect the views es the National Research Council or the National

Academy of Sciences of the U.S.A.

Source : MNHN, Paris

34 ALYTES 9 (2)

INTRODUCTION

The workshop was organized because of an increasing awareness among biologists

around the world that many populations and species of amphibians (frogs, order Anura;

salamanders, order Caudata; caecilians, order Gymnophiona) have experienced declines

and extinctions, even in protected natural areas. Internal funding from the National

Research Council was obtained in November 1989 by the Board on Biology, and a

workshop was organized by David B. WAKE and Harold MoROWITZ, members of the

Board on Biology, and by the staff of the Board. The workshop included presenters of

information and discussants representing an array of disciplines (see Appendix).

FINDINGS

The workshop addressed the proposition that “ worldwide, amphibian populations

are in decline. ” To a degree, this is true, but the statement is not universally applicable

to all taxa in all locations, nor is there evidence of a single planetary causal factor. Drastic

habitat modification by humans is a major cause of decline in amphibian populations, but

other human activities are also important. However, the decline and extinction of some

amphibian populations in seemingly pristine areas cannot be directly tied to human

activities.

I. DATA-BASED CONCLUSIONS

A. Many montane species of western North America are in decline, even in protected

preserves and undisturbed areas where habitat alteration is not apparent. Montane areas

in other regions of the New World also have declining amphibian populations (e.g.,

Middle America, Atlantic Coastal forest of Brazil). Frogs from some low elevation sites

in different parts of the world are declining or have disappeared. Many declines first

became evident in the period between 1978 and 1982, although some occurred earlier.

B. Populations of several species in different areas (northwestern United States,

southern and eastern Canada, and eastern Australia) have experienced severe declines at

many sites, but data are fragmentary.

C. Populations in some regions, such as the southeastern United States, show little

evidence of general declines, apart from that clearly attributable to habitat destruction.

D. In some habitats, declining and stable species co-occur; for example, populations

of the Wood Frog, Rana sylvatica, appear to be stable in the Rocky Mountains, but

populations of the Leopard Frog, Rana pipiens, in the same area are declining.

Accordingly, there is species-specificity in the response to factors causing declines.

(1) Reasons for species specificity may be attributable in part to differences in physiolog-

ical (e.g., tolerance to low pH), behavioral, ecological (e.g., short developmental

period), or other properties.

Source : MNHN, Paris

DECLINING AMPHIBIANS POPULATIONS 35

(2) Declining and stable species sometimes are related phylogenetically, such as being

members of the same genus.

(3) Certain species are experiencing difficulty over broad regions, yet appear to be doing

well in other locations.

E. No evidence was presented for declines of populations living at low elevations in

equatorial regions (between 10 degrees N and S latitude), except in areas of severe habitat

destruction (e.g., timber harvest, agricultural practices such as grazing and irrigation,

desertification). Information from long-term studies is available only for Borneo and

Panama.

F. Where declines and extinctions are documented, we generally do not know which

stages of the life cycle are most affected. No specific pathologic conditions thus far have

been identified to suggest a unifying theme for the declines; however, infectious disease

agents or toxins have not been adequately studied and cannot be ruled out as possible

causative factors.

G. About 5,000 species of amphibians have been described throughout the world,

with most species being found in the tropics. In general, little is known about the status

of most species. However, evidence is available from a wide variety of sources to support

the main finding of decline in many species and in many areas.

Il. ANTHROPOGENIC FACTORS

A. Anthropogenic factors have been and continue to be important in population

declines and local extinctions in most areas. These include acid precipitation, heavy metal

discharge and mobilization, pesticide release, deforestation, hydrological modification and

changes in patterns of land-use (urbanization, changed agricultural practices, extention of

agriculture to wetlands, release of irrigation waters, and the like).

B. Wildlife management practices, such as the stocking of previously pristine lakes

and streams with fish that are predators of amphibians, have contributed substantially to

declines in some areas.

C. In two cases (western North America and eastern Australia), the introduction and

subsequent proliferation of non-native anurans (the Bullfrog, Rana catesbeiana, for food

and sport, and the Cane Toad, Bufo marinus, as a biological control of insect pest) have

contributed to the decline of native amphibians. Populations of the Bullfrog (even

introduced populations) are now in decline in many areas, but the Cane Toad is thriving

and has become a pest itself in Australia.

III. SPECIAL PROPERTIES OF AMPHIBIANS

A. Amphibians are sensitive bioindicators of environmental change because of their

physiological and behavioral characteristics, life-historical and morphogenetic patterns,

and features of their population biology.

Source : MNHN, Paris

36 ALYTES 9 (2)

B. The skin of amphibians is highly permeable to gases and liquids in the

environment; as a result amphibians are intimately exposed to materials in the water, air,

and terrestrial substrate.

C. High fecundity, complex life cycles (with larval and adult stages usually occupying

different habitats), and fragmented but interconnected population structures may render

amphibians sensitive to diverse environmental factors relative to other vertebrates. Biotic

and abiotic factors impinge on amphibians in many ways. Development in many frogs

takes place in water, and tadpole consume mostly plant materials. Special conditions must

be met in order for metamorphosis to succeed. Metamorphosed animals typically are

terrestrial or semi-terrestrial, and invertebrates (especially insects) are major prey.

Accordingly, those factors that affect riparian and aquatic vegetation and insects can also

affect larval and adult amphibians. In some regions, adults may also undergo seasonal

aestivation and hibernation, and they are thus subject to additional environmental factors.

Populations often occur as subpopulations in neighboring ponds, and individuals may

breed in one pond during one year, but another the next. These features combine to expose

amphibians to a wide variety of influences during their lives.

While the life history outlined above is well known and is typical of many species,

amphibians are a very diverse group. Most caecilians, about one-half of the species of

salamanders, and hundreds of species of frogs are strictly terrestrial throughout their lives,

and other species of all three groups are strictly aquatic. Some salamanders are permanent

larvae, and many species in all groups have direct development with no larval stage. A few

frogs and salamanders are live-bearing, and most caecilians are viviparous. This diversity

in development, life history and ecology adds to the suitability of the group as a whole for

studies of biodiversity.

D. The additive or synergistic effects among a number of global, regional and local

factors may result in substantial declines.

E. Environmental acidity appears to play a major role in declines of amphibian

populations. Some species have evolved in low pH environments, but many others have

not experienced acidity in their evolutionary history and so are especially sensitive to

lowering of pH, and the toxicity of metals such as aluminum that are biologically active

at low pH, during specific phases of embryogenesis.

RECOMMENDATIONS

The stresses on most declining amphibians and their habitats are of human origin.

Anthropogenic effects on the scale of global to local environment are complex, and their

remediations will require an understanding of ecosystem functions. The pursuit of such

studies depends on the knowledge, skills and cooperation of scientists from many

disciplines. Such research will inevitably be labor-intensive and will require use of modern

technology. This will demand a broad range of new human and financial resources.

Recommendations are grouped in four general categories.

Source : MNHN, Paris

DECLINING AMPHIBIANS POPULATIONS 37

I. LONG-TERM STUDIES OF AMPHIBIAN POPULATIONS ARE NEEDED, WITH SPECIAL EMPHASIS

ON THE FOLLOWING

À. Studies focusing on the significance of amphibians in ecosystems

The significance of salamanders in ecosystems needs clarification. In some ecosystems

(e.8., at Hubbard Brook, N.H.), amphibians have been shown to have the greatest animal

biomass, but little information is available for other areas. New studies should focus on

the role of both larval and adult amphibians in the food web, and the unique potential of

amphibians as indicators of the health of the ecosystem. Such studies should be established

at selected strategic sites around the world, or incorporated into ongoing programs.

Ideally, these studies will be conducted within the context of long-term population studies.

Amphibians have properties which make them especially useful bioindicators in

ecosystem studies. Specific reasons are listed below.

(1) Most species have complex life cycles, with both aquatic and terrestrial phases.

(2) Amphibians have permeable skins, which result in large and rapid material exchange

with the environment including water, air, and terrestrial substrate. Because of their

susceptibility to different factors, they are especially sensitive early-warning indicators

of certain types of environmental changes.

(3) Amphibians are small to intermediate-sized vertebrates; their fate has direct relevance

to that of other vertebrates, including humans. They are high in the food web, and

their decline is a signal of deeper ecosystem deterioration, including factors reducing

populations of invertebrates and plants.

(4) Amphibian biomass constitutes an appreciable fraction of many terrestrial ecosystems;

they have been shown to be the dominant vertebrate group in some ecosystems.

(5) The demise of amphibians has inevitable, major effects on other components of

ecosystems.

B. Studies focusing on the population biology of amphibians

We recommend that long-term population studies be conducted to identify abiotic

and biotic factors that account for temporal patterns of diversity and abundance of

amphibians under unaltered conditions, so that baseline data can be generated and

amphibians can serve as indicators of environmental change in ecosystems. Depending on

local diversity, these studies will deal with entire assemblages or with focal species. Such

studies should be distributed geographically to take into account patterns of diversity

based on differences in latitude, elevation, habitat, and taxonomy. Of special importance

is the interaction between habitat fragmentation and population structure. Long-term

monitoring in these studies should focus on:

(1) Population dynamics, including age-specific birth and death rates, mechanisms of

population regulation, and demographic responses to pollutants.

Of special importance is an understanding of the spatial and temporal patterns of

Source : MNHN, Paris

38 ALYTES 9 (2)

fluctuation in population size through time, which relates directly to long-term persistence

and vulnerability of isolated populations and populations inside nature preserves that are

surrounded by degraded habitats.

(2) The relationship of physical and chemical variables in the environnement to the

changes in the amphibian populations being studied.

Care must be taken to standardize the collection and analysis of physical variables

and to design population studies to allow for the unique characteristics of each system.

Experiments should be designed to test hypotheses generated by long-term monitoring

studies. Success of this phase requires formal and regular communication among research

groups as well as dependable long-term support. Attempts should be made to integrate

population and ecosystem studies, where feasible. Renewable funding intervals should

extend over periods of five years or longer, because life spans of amphibians are relatively

long and the dynamics of population cycles (related to variable weather and other factors)

must be understood over a relatively long time frame to allow valid interpretations of the

data.

C. Studies focusing on the relationship of chemical and physical factors to individual

organisms and populations

Efforts must be made to identify possible chemical and physical causes of amphibian

decline on a broad scale. Because different causes probably account for the decline of

different populations, we propose the careful selection of specific populations with

documented declines for special study. The target of such studies should be species with

complex life cycles. Embryonic and larval development should be compared in water where

the eggs were found, and in water of known high quality. The water samples should be

analyzed for their chemical constituents, including major ion concentrations, pesticides,

herbicides, and other components of the environment. Selected individuals should be

followed from early development through sexual maturity, in order to detect possible

stage-specific effects. Meteorological conditions such as temperature, humidity, rainfall,

ultraviolet intensity and atmospheric ozone at the collection sites should be monitored

continuously.

Moribund and dead specimens should be collected for pathological studies, to include

histologic, microbiologic, and toxicologic analyses. Healthy control animals should be

submitted for study at the same time.

II. COMPILATION OF INFORMATION, AND USE OF HISTORICAL DATA

Many past studies contain critical information about amphibians, including historical

occurrence, population density, survivorship of various life history stages, and other

variables. We recommend that as far as possible future studies be designed to take

advantage of these prior investigations, which can serve as baselines. Such information will

Source : MNHN, Paris

DECLINING AMPHIBIANS POPULATIONS 39

be especially valuable in regions where amphibian populations are known or suspected to

be in decline.

A. Much useful information can be derived from museum records and the literature

There is a rich data base in the collections of the natural history museums of the

world, and in publications. There are also some other sources of information, such as

records of field stations and long-term but unpublished studies by individual investigators.

These sources should be utilized thoroughly. We recommend that full advantage be taken

of bibliographic and museum data, so that we might be better able to detect changes in

amphibian populations that occur over long time intervals (decades or even centuries).

This method would take advantage of the large, existing data sources and would be

particularly useful in detecting both changes in distribution and relative abundance, given

an understanding of the limitations and advantages of such data. Most important,

identified changes then could be correlated with a variety of morphological, ecological,

climatic, geographic and phylogenetic parameters that can assist in identifying problem

groups, areas, or conditions, and relevant factors responsible for such declines and

extinctions.

B. Ecological and population data from previous studies should be evaluated to determine if

they can be used as a base for comparative studies

This is an approach that will develop a series of samples from two or more periods

of time. If such studies are amplified sufficiently they will produce enormous quantities of

information at relatively low cost. The following sampling approaches should be

undertaken:

(1) Resurvey of previously studied populations.

In many instances it may be possible to resurvey the exact sites at which prior studies

were conducted, and it may be possible to convince the original investigators to return to

these sites so as to control as much as possible for methods of sampling.

(2) Surveys of historical localities derived from museum and literature records, and from

unpublished field notes of investigators.

Areas to be studied would be selected to represent diverse taxa and geography, and

would include areas showing population declines. Protocols for sampling must be

developed for each taxon and region in order to assess accurately the presence or absence

of a population, and in certain cases, aspects of population structure. This is especially

important because many amphibians are secretive organisms, difficult to find except when

they are breeding.

Source : MNHN, Paris

40 ALYTES 9 (2)

III. INVESTIGATE THE FEASIBILITY AND DESIRABILITY OF ESTABLISHMENT OF A NEW

ORGANIZATION, WHICH WOULD BE FOCUSED ON ISSUES OF MAINTENANCE OF

BIODIVERSITY

Existing environmental organizations and governmental organizations often fail to

respond appropriately and promptly to the kinds of crises and challenges described here.

Institutional structural changes or innovations may be needed. We recommend that the

Board on Biology examine this problem, and initiate one or more formal studies with the

following parts:

A. An analysis of the benefits and disadvantages of different institutional models,

both governmental and non-governmental, for the support and funding of research of the

following general kinds:

(1) The discovery, testing, and utilization of taxa and interacting subsets of communities

and ecosystems that will permit and facilitate early detection of environmental

deterioration.

(2) The development of guidelines aimed at the management of natural systems and for

remedial actions in such systems.

B. An analysis of organizational mechanisms that would maximize the flexibility and

efficiency of institutions; among these might be peer review processes, rotation of advisory

board membership, and establishment of program priorities and directions.

À proposal has been made by another group of concerned individuals for the

establishment of a National Institute for the Environment (N.LE.). It is possible that one

role of such an organization would be the function we have outlined. Accordingly, an

alternative recommendation is that the Board on Biology conduct a study based on the

proposal for N.LE.

IV. DESIGN AND DEVELOPMENT OF EDUCATIONAL PROGRAMS THAT WOULD KEEP THE

PUBLIC INFORMED CONCERNING THE STATUS OF POPULATIONS AND SPECIES OF CRITICAL

TAXA (SUCH AS AMPHIBIANS) AROUND THE WORLD, AND OF THEIR SIGNIFICANCE FOR

ISSUES IN BIODIVERSITY

V. IN ADDITION TO THE MAIN LONG-TERM RECOMMENDATIONS, SEVERAL IMMEDIATE ACTIONS

SHOULD BE TAKEN

A. Distribute a summary of the main results of this workshop in appropriate outlets.

B. Distribute the main findings and recommendations of this workshop to appro-

priate organizations and individuals, including workshop participant.

C. Convene a more specialized workshop, symposium or meeting with the tentative

title: Declining amphibian populations: biomonitoring, analyses of factors and future

Source : MNHN, Paris

DECLINING AMPHIBIANS POPULATIONS 41

directions. Such a meeting would: (1) compile and analyze the current data on declining

populations, using present trends to predict future changes in species richness and

diversity; (2) identify critical areas in need of intensive study; (3) develop a protocol for

long-term monitoring of selected amphibian populations, species and communities, with

consideration of the relationship of amphibians to the dynamics of ecosystems, the

patterns of amphibian population dynamics, and the identification of critical physical and

chemical parameters for amphibian life history; and (4) study and recommend sources of

funding for long-term investigations. The workshop should include both amphibian

biologists and experts in the subject areas relevant to the problems considered (e.g.,

ecotoxicology, climatology, water quality, physiology, development, population biology,

wildlife and fisheries, systematics).

D. Establish a committee to organize a large-scale international symposium and seek

funding for it [perhaps under the aegis of the International Society for the Study and

Conservation of Amphibians (ISSCA)].

E. Improve communication among members of the biological community concerned

with amphibian diversity, population biology and ecology. The International Society for

the Study and Conservation of Amphibians is an existing organization that might well

serve this function.

APPENDIX

WORKSHOP PARTICIPANTS

Chairman: David B. Wake, University of California, Berkelev.

Co-Chairman: Harold J. MOROWITZ, George Mason University, Virginia.

SPEAKERS

Andrew BLAUSTEIN, Oregon State University, Corvallis.

David BRADFORD, University of California, Los Angeles.

R. Bruce Bury, National Ecology Research Laboratory, US. Fish and Widlife Service, Ft.

Collins, Colorado.

Janalee CALDWELL, University of California, Los Angeles.

P. Steven Corn, National Ecology Research Laboratory, U.S. Fish and Wildlife Service,

Ft. Collins, Colorado.

Alain Dumois, National Museum of Natural History, Paris.

John HARTE, University of California, Berkeley.

Marc HAYES, University of Miami, Florida.

Robert INGER, Field Museum of Natural History, Chicago.

H.-K. NETTMANN, University of Bremen, Federal Republic of Germany.

A. Stanley RAND, Smithsonian Tropical Research Institute, Panama.

David Smrrx, Williams College, Massachusetts.

Source : MNHN, Paris

4 ALYTES 9 (2)

Michael TYLER, University of Adelaide, Australia.

Laurie Virr, University of California, Los Angeles (and Savannah River Ecology

Laboratory, South Carolina).

COMMENTATORS AND ANALYSTS

James MACMAHON, Utah State University, Logan.

Bassett MAGUIRE, University of Texas, Austin.

Richard MONTALI, National Zoological Park, Washington, D. C.

Vaughan SHOEMAKER, University of California, Riverside.

Peter SMOUSE, Rutgers University, New Jersey.

Richard TURCO, University of California, Los Angeles.

Richard WaAssERSUG, Dalhousie University, Halifax, Nova Scotia, Canada.

Henry Wizsur, Duke University, North Carolina.

DISCUSSANTS, OTHER PARTICIPANTS, AND OBSERVERS

Francisco J. AYALA, University of California, Irvine (Board on Biology); Michael E.

SouLé, University of California, Santa Cruz (Board on Biology); Malcolm S. STEINBERG,

Princeton University (Board on Biology); Donald E. STONE, Duke University (L.U.B.S.;

Organization for Tropical Studies); Marvalee H. Wake, University of California, Berkeley

(LU.B.S.); George JOHNSON, Washington University, St. Louis (L.U.B.S.); G. Carleton

RAY, University of Virginia, Charlottesville (LU.B.S.); George B. RaBB, Chicago

Zoological Society (President, Species Survival Commission, I.U.C.N.); Roy W. McDiar-

MD, US. Fish and Wildlife Service (National Museum of Natural History); John W.

WRIGHT, Natural History Museum, Los Angeles County; Mark JENNINGS, California

Academy of Sciences, San Francisco; Stephen REILLY, University of California, Irvine;

John CaRR, Conservation International, Washington, D.C.; Oskar R. ZABoRskY, Board

on Biology, National Research Council; Donna M. GERARDI, Board on Biology, National

Research Council; John E. Burkis, Commission on Life Sciences, National Research

Council; Marietta E. ToAL, Board on Biology, National Research Council.

Source : MNHN, Paris

Alytes, 1991, 9 (2): 43-50. 43

Declining amphibian populations

— a global phenomenon?

An Australian perspective

Michael J. TYLER

Department of Zoology,

University of Adelaide,

Box 498, G.P.O.,

Adelaide, S.A. 5001, Australia

Evidence that populations of at least 10 % of the Australian amphibian

species are subject to serious decline is reviewed. Causal factors can currently

be identified in just a few of these cases. On the other hand, a few amphibian

species are expanding their range in Australia, but this phenomenon is much

more limited in scope.

INTRODUCTION

Anurans are the only amphibians native to Australia. A few species of caudates have

been imported by aquarists; one of them (the axolotl) has been released in the wild in

Tasmania and has become established there.

A significant proportion of the Australian frog fauna has been discovered or described

within the past 30 years. MooRE (1961) recognised 90 species throughout the continent.

My current estimate is that there are 194. I am aware of descriptions of five new species

in press and I estimate that at least 25 more species remain to be discovered or described.

Because Australia is a vast continent with a small population and few herpetologists,

it is understandable that increases or decreases in the frequency of occurrence of frog

species often need to be dramatic to attract comment. Comments by OSBORNE (1986, 1989)

are noteworthy.

In fact concerned Australians have been exposed to evidence of an environmental

disaster created by the expansion of an amphibian population: the colonisation of the

continent by the introduced species Bufo marinus. The fact that the Prime Minister, Mr.

* This paper was presented during the workshop on “ Declining amphibian populations — a global

phenomenon? ”, organised by the Board on Biology of the National Research Council of the U.S.A., which

was held at Irvine (California, U.S.A.) on 19-20 February 1990.

Source : MNHN, Paris

44 ALYTES 9 (2)

Bob HAWKE, made a commitment to fund research to control this species in a 1989

statement on his government’s environmental policy, is a clear indication of the serious

concern about the only amphibian species in the world to be declared a pest.

Against a background of the proliferation of an amphibian species, it follows that

evidence of decline of native species needs to be dramatic to be heeded. Unfortunately,

there is now ample evidence of serious localised declines affecting at least 10 % of the

Australian frog fauna.

These declines have occurred within the last decade and there are two examples of

possible extinction of species: the gastric brooding frog Rheobatrachus silus and

Taudactylus diurnus.

NORMAL POPULATION FLUCTUATIONS

Under certain geographic and climatic conditions, enormous fluctuations occur in the

populations of a number of species of Australian frogs. This is particularly evident in the

arid northeastern deserts of South Australia, where maximum temperatures average

36-39°C in summer (ALLAN, 1990). Median annual rainfall is 100-150 mm, whilst mean

annual evaporation exceeds 3600 mm (KoTwicki, 1986, 1987). Periodic flooding of the

area principally from creeks flowing down from the Northern Territory and from

Queensland, transport frogs which breed and proliferate to form massive populations in

temporary, freshwater lakes. Subsequent periods of aridity produce total extinction of

those populations. Thus the frog fauna of that area exhibits great cyclic swings from

millions to zero. These events are normal, anticipated and acceptable to a human observer.

It is possible that wild fluctuations also occur in temperate forest. The evidence is

partly circumstantial but compelling. As discussed by CZECHURA (1990), the evidence

partly hinges upon the question of why newly discovered species are found in abundance

in areas previously sampled. Classic examples are Rheobatrachus silus and Taudactylus

diurnus in southeast Queensland, and Litoria brevipalmata in northern New South Wales

(G. F. WaTsonN, in litt.). Each instance was followed by a dramatic decline that can be

dated (see p. 45).

DATA SOURCES

Very few declines of frog populations have been documented in the literature. In

assembling data at the instigation of Dr. D. B. WAKeE, I wrote to colleagues throughout

Australia. For their responses I am indebted to the following:

— K. R. McDoNALD, Queensland National Parks & Wildlife Service, Townsville.

— G.F. WATSON, Department of Zoology, University of Melbourne, Melbourne.

— M.J. LITTLEJOHN, Department of Zoology, University of Melbourne, Melbourne.

— L. A. SmrrH, Western Australian Museum, Perth.

Source : MNHN, Paris

TYLER 45

— J. D. RoBerTs, University of Western Australia, Perth.

— J. WomBey, C.S.I.R.O. Division of Wildlife & Ecology, Canberra.

— G. V. CZECHURA, Queensland Museum, Brisbane.

M. KING, Northern Territory Museum & Art Gallery, Darwin.

W. OsBORNE, Canberra College of Advanced Education, Canberra.

R. G. BECK, Lynwood Park, Mil-Lel, South Australia.

— G. C. GRIGG, Department of Zoology, University of Queensland, Brisbane.

GEOGRAPHIC DISTRIBUTION OF DECLINING POPULATIONS

Al of the reports of species in decline are within the southern half of the continent,

and the majority of these border the Great Dividing Range in the east and southeast (fig.

1).

SPECIES SUBJECTED TO DECLINE

Although I do not dispute statements that frogs are not as plentiful as they used to

be in certain areas, I have included in Table I only those where there is evidence of a

substantial change in abundance or significant contraction of range.

1 have excluded contractions of range readily attributable to local urbanisation and

land clearance. I have focussed attention upon those species in which there has been a

dramatic decline over the past decade. This time frame is significant, for insofar as 1 can

gather the crucial changes probably commenced in the period 1979-1983.

LIKELY CAUSAL FACTORS

It is possible to identify the causal events of declines of just a few species included in

Table I.

For example, the apparent disappearance of species at Lake Dumbleyung in Western

Australia has been attributed to salination. The problem is widespread in parts of

Australia, but the variation in capacity to withstand high salt levels appears to be

associated with skin thickness. However, it is presumably the aquatic embryos that are

vulnerable.

The dependence of frogs upon moisture, and the severity of droughts in Australia

permits the obvious conclusion that drought must be a potential significant factor

producing localised extinctions. The drought in 1982-1983 in southeastern Australia that

was a consequence of the El Niño must have produced localised extinctions, but not on

the scale that has been observed.

The demise of Rheobatrachus silus occurred in about 1980. The significance of the

species because of its unique habit of gastric brooding meant that it was the subject of

Source : MNHN, Paris

46 ALYTES 9 (2)

Fig. L.

(hatched).

- The geographic zones where declines of frog populations have been noted in Australia

Source : MNHN, Paris

TYLER

Table I. — Species of Australian frogs exhibiting declines.

Species

Geographic area affected

Significance of decline

Crinia georgiana

Geocrinia laevis

G. victoriana

Heleioporus eyrei

Limnodynastes dumerilii

L. tasmaniensis

Litoria adelaidensis

L. aurea

L. ewingi

L. flavipunctata

L. lesueuri

L. pearsoniana

L. raniformis

L. spenceri

L. verreauxi

Pseudophryne bibroni

P. corroboree

P. dendyi

P. semimarmorata

Rheobatrachus silus

R. vitellinus

Taudactylus diurnus

T. eungellensis

Lake Dumbleyung, W.A.

S. & Central Victoria

Perth metropolitan area

S.E. South Australia,

S. & Central Victoria

S.E. South Australia,

S. & Central Victoria

Lake Dumbleyung, W.A.

Uncertain. At least from

southern N.S.W.

S. & Central Victoria

A.CT. & NS.W.

S.E. Qid.

S.E. QId.

SE. SA. S. &

Central Victoria

Victoria

A.CT.

S.& Central Victoria,

southern N.S.W.

ACT. & S. N.S.W.

S. & Central Victoria

S.E. South Australia,

S. & Central Victoria

S.E. Qid.

Central eastern QId.

S.E. QId.

Central eastern QId.

unknown

serious

unknown

serious

unknown

serious

unknown

serious - possibly extinct

serious

serious - possibly extinct

serious

Source : MNHN, Paris

48 ALYTES 9 (2)

extensive investigation and had a high public focus. Consequently its disappearance was

examined very closely which, for the purposes of this conference, was fortuitous. In fact

its disappearance typifies the problem that we address.

Rheobatrachus silus was discovered and described in 1973. It was abundant in

rainforest within a two hour drive of Brisbane. It was so abundant that an agile collector

could have picked up 100 in a single night. In 1974, CORBEN et al. reported the habit of

gastric brooding, but several years elapsed before a photographic record of birth was

obtained (TYLER & CARTER, 1981). And it was in 1981 that the species totally disappeared

in the wild. A captive colony was maintained in Adelaide for two further years.

The original distribution of the species was confined to the Conondale and Blackall

Ranges and occupied less than 100 km. The only population estimate was made by

INGRAM (1983), who arrived at a figure of 77 within his study site of 0.7 hectare.

The disappearance occurred over winter. The failure to locate individuals during

winter was a normal phenomenon. Thus it was several months before the absence was

recognised for what it was.

TyLer & DAVIS (1985) reviewed the following hypotheses that has been put up to

explain the demise:

(1) over-collecting by herpetologists;

(2) pollution of creeks brought about by logging;

(3) pollution of creeks caused by damming of sections associated with gold-panning;

(4) drought.

Each of these suggestions proved incapable of explaining the disappearance of the

species. It is worth observing that the species disappeared simultaneously from the

Kondalilla National Park.

This phenomenon of apparently inexplicable decline or disappearance is repeated

time and again in eastern Australia. Taudactylus diurnus whose range overlapped that of

R. silus also disappeared without trace. It had been even more abundant.

The demise or serious declines of the 22 species listed has taken place whilst other

species have expanded their ranges. It is possible that an appreciation of those success

stories may contribute to an understanding of the modern failures.

EXPANDING POPULATIONS

An account of the colonisation of Australia by Bufo marinus conforms to the tragic

list of introduced exotic species. A total of 102 individuals were imported in 1935 and their

offspring released at a series of sugar cane plantations on the Queensland coast. The

intention was to provide a biological control of insect pests of sugar cane. That objective

was not achieved and the toads had an impact that was not anticipated. Being toxic they

brought about the death of native animals that included amphibians in their diet. Having

a high fecundity they proliferated to such an extent that they decimated the ground-

Source : MNHN, Paris

TYLER 49

dwelling invertebrate fauna and, in the absence of significant predators, extended their

range beyond the cane plantations to a degree that was not conceived. The toads now

occupy 600,000 km and are moving west into the Northern Territory at at least 20 km per

year (TYLER, 1989). Serious attempts are being made to find an effective control agent.

One of the Australian native species may be expanding its range. The small marsh

frog Limnodynastes tasmaniensis of southeast and east Australia appears adept at

establishment following accidental transportation. They were discovered at Kununurra in

the northwest of the continent in 1977 (MARTIN & TYLER, 1978) and at Mound Springs

in the outback of South Australia in 1976 (TYLER, 1978). It will be noted from Table I that

L. tasmaniensis numbers in the moister southeast have declined.

It has been suggested that in northern Australia frog numbers may have increased as

a direct result of human modification of the environment (TYLER, 1979). Road

construction (whether sealed or unsealed) is accomplished by the quarrying of road

building materials for foundations. These excavations, “ borrow pits ”, may be up to 300

* 100 m in extent. They hold water during the wet season. Being ephemeral water sources

they do not support aquatic predators of tadpoles such as fish. They constitute ideal

breeding sites for frogs and they have surely effected an increase in frog population

densities in the areas in which they occur.

In arid regions, excavation of permanent water sources with steep sides, and known

as “ turkey nest ” dams, has provided refuges for species such as Litoria latopalmata and

Crinia deserticola. There are also commensals such as the green tree frog Litoria caerulea

that inhabit homes, outhouses and particularly toilets in seasonally arid areas.

These “ artificial ” habitats have no doubt provided a secure environment for a few

species of frogs that are capable of exploiting such opportunities. Despite that positive

aspect, the decline of populations is of a different order of magnitude. I do not believe that

that decline can be attributed directly to human causes, although there may be

contributory factors.

RÉSUMÉ

Cet article présente les informations disponibles sur le déclin des Amphibiens en

Australie. Ces informations sont incomplètes, mais elles indiquent que des populations

d’au moins 10 % des espèces d’Amphibiens du pays manifestent un déclin important. Dans

la plupart de ces cas, les causes n’en sont pas encore connues. Par ailleurs, quelques espèces

d’Amphibiens voient actuellement leur aire de répartition en Australie augmenter, mais ce

phénomène est d’une ampleur bien plus limitée que le précédent.

LITERATURE CITED

ALLAN, R. J., 1990. — Climate. /n: M. J. TYLER, C. R. TWIDALE, M. Davis & C. B. WELLS (eds.),

Natural history of the north east deserts, Adelaide, Royal Society of South Australia: 81-84.

Source : MNHN, Paris

50 ALYTES 9 (2)

Core, C. J., INGRAM, G. J. & TyLer, M. J., 1974. — Gastric brooding: unique form of parental

care in an Australian frog. Science, 186: 946-947.

CzecaurA, G. V., 1990. — The Blackall-Conondale Ranges: frogs, reptiles and fauna conservation.

In: G. L. WERREN & À. P. KERSHAW (eds.), The rainforest legacy.

INGRAM, G., 1983. — Natural history. Zn: M. J. TYLER (ed.), The gastric brooding frog, Canberra,

Croom Helm: 16-35.

Korwicki, V., 1986. — Floods of Lake Eyre. Adelaide, Engineering & Water Supply Dept.

--- 1987. — On the future of a rainfall-runoff modelling in arid lands: Lake Eyre cast study. /n:

Water for the future: hydrology in perspective, Proc. Rome Symposium, I.A.H.S. Publ. 164.

MARTIN, À. A. & TYLier, M. J., 1978.— The introduction into Western Australia of the frog

Limnodynastes tasmaniensis. Aust. Zool., 19: 320-324.

MOORE, J. A., 1961. — Frogs of eastern New South Wales. Bull. Amer. Mus. nat. Hist., 121(3):

149-386.

OsBORNE, W., 1986. — Frogs of the Canberra region. Bogong, 7(3): 10-12.

--- 1989. — Distribution, relative abundance and conservation status of Corroboree frogs,

Pseudophryne corroboree Moore (Anura: Myobatrachidae). Aust. Wildl. Res., 16: 537-547.

TYLER, M. J., 1978. — Amphibians of South Australia. Adelaide, Govt. Printer: 1-84.

ue 1979. — The impact of European man upon Australian amphibians. /n: M. J. TYLER (ed.), The

status of endangered Australian wildlife, Adelaide, Royal Zoological Society of South Australia:

177-184.

= 1989. — Australian frogs. Melbourne, Viking O’Neil: i-xii + 1-220.

Tvuer, M. J. & CARTER, D. B., 1981. — Oral birth of the young of the gastric brooding frog

Rheobatrachus silus. Anim. Behav., 29: 280-282.

TYLER, M. J. & Davies, M., 1985. — The gastric brooding frog Rheobatrachus silus. In: G. GRIGG,

R. SHINE & H. EHMANN (eds), Biology of Australasian frogs and reptiles, Sydney, Royal

Zoological Society of New South Wales.

Corresponding editor: Alain DUBoIs.

Source : MNHN, Paris

Alytes, 1991, 9 (2): 51-58. sl

A developmental table of Crinia signifera

Girard, 1853

(Anura, Myobatrachinae)

Birgit GOLLMANN

Institut für Zoologie, Universität Wien, Althanstr. 14,

1090 Wien, Austria

Embryonic development of the Australian frog Crinia signifera is de-

scribed and illustrated. Most of the divergences found in a comparison with

related frogs of the Geocrinia laevis complex appear to be connected with

their different life histories. The applicability of the staging table of GOSNER

(1960) and of the table modified for Geocrinia (GOLLMANN & GoLLMANN, 1991),

is evaluated.

INTRODUCTION

Crinia signifera Girard, 1853 is a small, widespread and abundant frog of Southeast-

ern Australia (Myobatrachidae, Myobatrachinae). It shows an opportunistic reproductive

strategy, spawning in a wide range of often rather unpredictable habitats throughout an

extended breeding period. Oviposition is aquatic, usually in shallow water after rain. The

eggs are deposited singly or in small groups, often attached to plants (COGGER, 1986;

WILLIAMSON & BULL, 1989).

Early embryonic development, up to the onset of heart beat, follows the “ typical ”

anuran pattern; MOORE (1961) used the development of Rana sylvatica (POLLISTER &

Moore, 1937) as a reference. Later embryonic development in Crinia diverges from this

“typical” pattern, most obviously by the complete absence of external gills. Conse-

quently, most staging tables developed for other anurans (e.g. POLLISTER & MOORE, 1937;

Gosner, 1960) cannot be used for C. signifera during this phase of development. In studies

of embryonic development in related frogs of the Geocrinia laevis complex, we developed

a modified staging table (GOLLMANN & GOLLMANN, 1991), using the table of GosNER

(1960) as a frame of reference and redefining stages when necessary.

It appeared worthwhile to compare the embryonic development of Crinia and

Geocrinia, which differ markedly in their life histories. Frogs of the G. laevis complex

deposit their eggs on land; hatching occurs at an advanced tadpole stage, after the spawn

has been flooded (LITTLEIOHN & MARTIN, 1964). Moreover, a detailed study of the

development of C. signifera provided a test case to see whether the staging table developed

for Geocrinia could be applied to related genera.

Source : MNHN, Paris

52 ALYTES 9 (2)

The assignment of C. signifera to genus and family has been subject to debate. BLAKE

(1973) resurrected the genus Ranidella Girard, 1853. The validity of this action was

questioned by HEYER et al. (1982). I take the more conservative approach, using the generic

name Crinia, without wanting to express an opinion on this taxonomic problem. Likewise,

the use of the name Myobatrachidae for what were formerly known as the Australian

members of the Leptodactylidae is controversial (TYLER, 1989). However, the subfamily

Myobatrachinae (containing both Crinia and Geocrinia), which is recognized in all current

classification schemes, seems to be a well defined taxon (see e.g. WATSON & MARTIN,

1973). Relationships within the Myobatrachinae are less clear: before the study of BLAKE

(1973), the species contained in Crinia and Geocrinia were regarded as congeneric; recent

immunological investigations (MAXSON & ROBERTS, 1985) suggest that these two genera

are not very closely related and may have diverged already in the late Cretaceous.

MATERIAL AND METHODS

Three amplectant pairs of C. signifera were collected in a small temporary pool 5.5

km ENE of Yan Yean, Victoria (37°33"S, 145°10'E), on the evening of 10 April 1989.

They were transported in plastic bags to the University of Melbourne. Each pair was then

put into a small aquarium containing approximately 1.51 of 5 % Holtfreter’s solution and

a few stems of Ceratophyllum sp. The aquaria were placed in a room with natural light and

a temperature of about 20°C. By the next morning, all three pairs had spawned. In the

afternoon of 11 April, about 20 eggs of each clutch were put into a Petri dish of 10 cm

diameter, containing 5 % Holtfreter’s solution, and transferred into a constant tempera-

ture room set at 15°C, with a 12 hour light-12 hour dark rhythm. They were inspected

under a dissecting microscope at intervals of about 24 hours each morning; on the third

and fourth day additional controls were made in the afternoon (six and eight hours,

respectively, after the first one).

Egg diameters of ten eggs per clutch were measured with an ocular micrometer before

the onset of neurulation (stage 12). Photographs of an embryo were taken daily from the

third to the fourteenth day. After the animals had completed embryonic development, they

were released in the pond where their parents had been collected and released after having

spawned in the laboratory.

RESULTS

At late stage 12 (GOsnER, 1960), eggs were about 1.3 mm in diameter. Cleavage,

blastular and gastrular stages as well as the closing of the neural folds of the embryos of

C. signifera conform to the typical pattern of anuran development. The tail bud (GOSNER

stage 17) grows out dorsally (MooRE, 1961). Despite the resulting unusual U-shape of the

embryo (fig. 1A), GosnER‘'s table can be used to identify developmental stages up to stage

19 (onset of heart beat; fig. 1B, C). For stages 20 to 26, I used the staging table developed

for Geocrinia by GOLLMANN & GOLLMANN (1991). These stages are defined as follows:

Source : MNHN, Paris

GOLLMANN 53

stage 20: mouth open; stage 21: first appearance of expanded melanophores; stage 22:

choroid fissure closed; stage 23: eye entirely black; stage 24: 1-2 rows of labial teeth; stage

25: 3-4 rows of labial teeth; stage 26: 5 rows of labial teeth.

Crinia signifera can be staged according to this table, since the characteristics used to

define the stages can be observed in the same order as they appear in Geocrinia. In the

following description of the development of C. signifera, divergences from the observations

made on G. laevis and G. victoriana (GOLLMANN & GoLLMANN, 1991) are stressed.

Stage 20 is very brief in C. signifera. The opening of the mouth is soon followed by

the appearance of melanophores. A long rectal tube has developed.

During stage 21 (fig. 1D), the cornea becomes transparent; the horseshoe-shaped optic

cup becomes faintly visible. Its pigmentation begins in the dorsal part, gradually increasing

towards the anterio-ventral side. Late at this stage, blood circulation in the tail fin can be

observed. The operculum begins to develop, overgrowing the gill plates, leaving only two

broad slits on the ventral side. Iridescent chromatophores appear on head, trunk and tail

(in G. laevis they were first seen at stage 23). They are concentrated in two broad stripes

from the eyes to the dorsal edge of the tail myotomes. About half of the embryos have

hatched at the end of this stage.

At stage 22 (fig. 2A), only the left slit of the operculum remains. Later on, it develops

into the spiraculum. Most embryos have hatched.

At stage 23 (fig. 2B), the horny jaws become visible. Towards the end of this stage,

a faint outline of the coiled gut as well as a tiny limb bud can be seen. By now, all animals

have hatched.

Labial papillae become discernable only at stage 24 (fig. 2C). A slight reduction of the

oral suckers can be noticed.

The inner row of teeth on the upper labium, which appears at stage 25 (fig. 2D),

consists of two parts divided by a wide gap. The narrow gap in the inner row on the lower

labium is hardly visible. The oral suckers have been further reduced to flat, dark-brown

rudiments.

At stage 26, brown patches are the only indication of the former position of the oral

suckers. The outermost row of labial teeth, which now develops, is about half as long as

the other two rows on the lower labium. The body wall of the tadpole is highly

transparent. No detailed observations of the larvae were made after they had reached stage

26.

DISCUSSION

The embryonic development of C. signifera is in many respects similar to that of

Geocrinia (GOLLMANN & GOLLMANN, 1991). Some of the divergences are probably

connected with the different life histories of the two genera (see Introduction). Crinia

signifera lacks the large yolk reserves necessary for the prolonged terrestrial life of the

embryos of Geocrinia. The eggs of C. signifera are smaller (TYLER, 1989; variation in these

Source : MNHN, Paris

ÿS

C D

Fig. 1. — Selected stages of the embryonic development of Crinia signifera. (A) Stage 17, lateral view,

13.4.1989, 18h00. (B) Stage 18, dorsal view, 14.4.1989, 9h45. (C) Stage 19, lateral view, 15.4.

1989, 11h40. (D) Stage 21, dorsolateral view, 17.4.1989, 10h50.

Source : MNHN, Paris

A B

Le]

C D

Fig. 2. — Selected stages of the embryonic development of Crinia signifera. (A) Stage 22, lateral view, ee

19.4.1989, 9h10. (B) Stage 23, lateral view, 21.4.1989, 11h00. (C) Stage 24, ventrolateral view,

22.4.1989, 13h00. (D) Stage 25, ventral view, 24.4.1989, 13h15.

Source : MNHN, Paris

56 ALYTES 9 (2)

19 21 22 28 24 26 GOERNER

19 20 21 22 23 24 25 26 »Geocrinia”

EU A 7 É7

5 6 7 8 9 10 11 12 13 14 15

Fig. 3. — Stages in the development of Crinia signifera, determined with the staging tables of GOSNER

(1960; above) and GOLLMANN & GOLLMANN (1991; below) (d = days since spawning). Because

external gills are absent, GOSNER stage 20 could not be identified and GOsNER stages 24 and 25

could not be clearly distinguished.

species is greater than indicated there: WiLLIAMSON & BuLL, 1989; GOLLMANN &

GOLLMANN, 1991) and develop at a faster rate. Under identical laboratory conditions, the

development from stage 17 to stage 26 took 16 to 20 days in Geocrinia (B. GOLLMANN,

unpubl.), but only 12 days in C. signifera.

Hatching occurs earlier in C. signifera (stage 21 to 23) than in Geocrinia (stage 26 or

27). The timing of the resorption of the oral suckers is apparently correlated with the stage

at which hatching occurs: maximal development of these organs is usually observed in

newly hatched tapdpoles, i.e. in earlier stages in North American anurans (GOSNER, 1960)

and in later stages in Geocrinia (GOLLMANN & GOLLMANN, 1991).

The smaller yolk sacs and the greater transparency of the embryos of C. signifera

allow the observation of operculum development (which cannot be seen in Geocrinia);

development of the cornea is also better visible. Therefore it is possible to identify most

of the stages of the GosnER table in embryos of C. signifera. À comparison of stages

according to the GOosnER table with the staging table used in this study (referred to as

“ Geocrinia table ” below) is presented in fig. 3.

The main cause of the great differences between the two tables in the timing of stages

is the unusually early and fast development of the operculum, which is probably connected

with the absence of external gills. With regard to other features, e.g. the mouth parts, the

Geocrinia table corresponds well to the GOsNER table. According to GosnER (1960), oral

disc and labial tooth rows begin to differentiate at about stage 23; by stage 26 their

essential peculiarities are present. In Geocrinia and C. signifera labial ridges begin to

develop at stage 23; at stage 26 all five rows of oral teeth have formed.

Although embryos of C. signifera can be staged with the GoseR table, the use of the

Geocrinia table seemed preferable: the characters used for stage identification in the latter

table were better visible in C. signifera, the rapid development of the operculum in C.

signifera lead to a highly unequal distribution of GosNER stages over developmental time

(fig. 3). Finally, comparative studies of embryology and life history variation can be

Source : MNHN, Paris

GOLLMANN 57

conducted in greatest detail among closely related forms. In several myobatrachine genera,

e.g. Geocrinia (GOLLMANN & GOLLMANN, 1991) and Pseudophryne (WOODRUFF, 1972), the

Gosner table cannot be applied during late embryonic development, whereas the Geocrinia

table provides a useful standard for comparison.

RÉSUMÉ

Le développement embryonnaire de la grenouille australienne Crinia signifera est

décrit et illustré. La plupart des divergences trouvées dans une comparaison avec les

grenouilles apparentées du complexe de Geocrinia laevis semblent liées à leurs modes de

développement différents. L'applicabilité à cette espèce de la table de développement de

GosnEr (1960) et de la table modifiée pour Geocrinia (GOLLMANN & GOLLMANN, 1991)

est évaluée.

ACKNOWLEDGEMENTS

L thank all members of the Department of Zoology, University of Melbourne, who helped me in

the course of this study; Terry BEATTIE solved many technical problems, David PAUL provided the

photographic equipment. Special thanks are due to Günter GOLLMANN, who captured the frogs and

assisted me with the preparation of the manuscript. The frogs were collected under National Parks

and Wildlife permit number RP-89-3.

LITERATURE CITED

BLAKE, A. J. D., 1973. — Taxonomy and relationships of myobatrachine frogs (Leptodactylidac): a

numerical approach. Aust. J. Zool., 21: 119-149.

Coccer, H.C., 1986. — Reptiles and amphibians of Australia. Ath ed. Sydney, Reed books: i-xxi +

17-688.

GOLLMANN, B. & GOLLMANN, G., 1991. — Embryonic development of the myobatrachine frogs

Geocrinia laevis, Geocrinia victoriana, and their natural hybrids. Amphibia- Reptilia, 12: 103-110.

Goswer, K. L., 1960. — A simplified table for staging anuran embryos with notes on identification.

Herpetologica, 16: 183-190.

HEYER, W.R., DAUGHERTY, C. H. & MaxsON, L. R., 1982. — Systematic resolution of the Crinia

complex (Amphibia: Anura: Myobatrachidae). Proc. biol. Soc. Wash., 95: 423-427.

LITTLEJOHN, M. J. & MARTIN, A. A., 1964. — The Crinia laevis complex (Anura: Leptodactylidae)

in South-Eastern Australia. Aus. J. Zool., 12: 70-83.

Maxsow, L.R. & ROBERTS, J. D. 1985. — An immunological analysis of the phylogenctic

relationships between two enigmatic frogs, Myobatrachus and Arenophryne. J. Zool., Lond.,

(A), 207: 289-300.

MOORE, J. A., 1961. — The frogs of Eastern New South Wales. Bull. amer. Mus. nat. Hist., 121:

151-385.

POLLISTER, A. W. & MOORE, J. A., 1937. — Tables for the normal development of Rana sylvatica.

Anat. Rec., 68: 489-496.

Tvyuer, M.J., 1989. — Australian frogs. Ringwood, Viking O'Neill: i-xii + 1-20, pl. 1-48.

Source : MNHN, Paris

58 ALYTES 9 (2)

WarsoN, G.F. & MARTIN, A. A., 1973. — Life history, larval morphology and relationships of

Australian leptodactylid frogs. Trans. r. Soc. S. Aust., 97: 33-45.

WiLLtAMsON, L. & Buzz, C. M., 1989. — Life history variation in a population of the Australian frog

Ranidella signifera: egg size and early development. Copeia, 1989: 349-356.

Woonrurr, D.S., 1972. — The evolutionary significance of hybrid zones in Pseudophryne (Anura:

Leptodactylidae). Ph. D. Thesis, University of Melbourne: 1-373.

Corresponding editor: Alain DUBOIS.

Source : MNHN, Paris

Alytes, 1991, 9 (2): 59.

Dates de publication du journal Alytes

(1990)

Alain DuBois

Laboratoire des Reptiles et Amphibiens,

Muséum national d'Histoire naturelle,

25 rue Cuvier, 75005 Paris, France

Cette liste fait suite à celles que nous avons déjà publiées (DuBois, 1988, 1989, 1990)

pour les années 1982-1989, et a été préparée de la même manière.

Volume Fascicule Pages Date figurant

sur le fascicule

1 1-24 January-April 1989

2 25-60 July-October 1989

RÉFÉRENCES BIBLIOGRAPHIQUES

Date réelle

de publication

4 juillet 1990

15 octobre 1990

Dumois, A., 1988. — Dates de publication du journal Alytes (1982-1987). Alytes, 6: 116.

1989. — Dates de publication du journal Alytes (1988). Alytes, 7: 75.

1990. — Dates de publication du journal Alytes (1989). Alptes, 8: 22.

Source : MNHN, Paris

Alytes, 1991, 9 (2): 60.

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Source : MNHN, Paris

ADVTES

International Journal of Batrachology

published by ISSCA

EDITORIAL BOARD FOR 1991

Chief Editor: Alain DuBois (Laboratoire des Reptiles et Amphibiens, Muséum national d'Histoire

naturelle, 25 rue Cuvier, 75005 Paris, France).

Deputy Editor: Günter GOLLMANN (Institut für Zoologie, Universität Wien, Althanstr. 14, 1090 Wien,

Austria).

Other members of the Editorial Board: Jean-Louis AMter (Yaoundé, Cameroun); Stephen D. BUSACK

(Ashland, U.S.A.); Tim HaLLiDAY (Milton Keynes, United Kingdom), William R. HEYER

(Washington, U.S.A.); Walter Hôp (Wien, Austria); Pierre JOLY (Lyon, France); Milos

KALEZIC (Beograd, Yugoslavia); Raymond F. LAURENT (Tucumän, Argentina); Petr ROTH

(Libechov, Czechoslovakia); Borja SaNcHiZ (Madrid, Spain); Dianne B. SEALE (Milwaukee,

U.S.A.); Ulrich SINsCH (Bonn, Germany).

Index Editor: Annemarie OHLER (Paris, France).

GUIDE FOR AUTHORS

Alytes publishes original papers in English, French or Spanish, dealing with amphibians. Beside

papers reporting results of original research, consideration will be given for publication to review

articles, comments and replies, and to papers based upon original high quality color photos of

amphibians, showing beautiful or rare species, interesting behaviors, etc.

The title should be followed by the name(s) and address(es) of the author(s). The text should be

organized as follows: English abstract, introduction, method, results, discussion, conclusion, French

or Spanish abstract, acknowledgements, literature cited.

Figures and tables should be mentioned in the text as follows: fig. 4 or Table IV. Figures

should not exceed 16 X 24 cm. The size of the lettering should ensure its legibility after reduction.

The legends of figures and tables should be assembled on a separate sheet. Each figure should be

pumbered using à pencil.

References in the text are to be written in capital letters (SOMEONE, 1989; EVERYBODY et al.,

1980; So & So, 1987). References in the literature cited section should be presented as follows:

— when in a periodical:

INGER, R. F., Vois, H. K. & Voris, H. H., 1974. - Genetic variation and population ecology of some

Southeast Asian frogs of the genera Bufo and Rana. Biochem. Genet., 12: 121-145.

— when in à multi-authors book:

GRAF, J.-D. & POLLS PELAZ, M., 1989. - Evolutionary genetics of the Rana esculenta complex. In:

R. M. DAWLEY & J. P. BOGART (eds.), Evolution and ecology of unisexual vertebrates, Albany, The

New York State Museum: 289-302.

— when a book:

BOURRET, R., 1942. - Les Batraciens de l'Indochine. Hanoï, Institut Océanographique de l’Indochine:

ix+1-547, pl. I-IV.

Manuscripts should be submitted in triplicate to Alain DuBois (address above) if dealing with

amphibian morphology, systematics, biogeography, evolution, genetics or developmental biology, or

to Günter GOLLMANN (address above) if dealing with amphibian population genetics, ecology,

ethology or life history.

Acceptance for publication will be decided by the editors following review by at least two

referees.

No page charges are requested from author(s), but the publication of color photographs is

charged. For each published paper, 25 free reprints are offered by A/ytes to the author(s). Additional

reprints may be purchased.

Published with the support of

the Muséum national d'Histoire naturelle (Paris, France).

Directeur de la Publication: Alain Dusois.

Numéro de Commission Paritaire: 64851.

@ISSCA 1551 Source : MNHN, Paris

Alytes, 1991, 9 (2): 33-60.

Contents

Declining amphibian populations — a global phenomenon?

Findings and recommendations 33

Michael J. TYLER À

Declining amphibian populations — a global phenomenon?

AN AUSTTANANMPETSDECHIVE Le AE en I IREM NIERERReRS 43

Birgit GOLLMANN

A developmental table of Crinia signifera Girard, 1853

(Anura,:My0batrachinae)| rente en er re MAR EP 51

Alain DUBoIs

Dates de publication du journal 4/ytes (1990) .......................... 59

Application for membership of ISSCA

and/or/subscriptiontto) Alyres 2 RE ERP PR OU 60

Biosis, Cambridge Scieftifie Abstracts,

s and The Zoological” Record.

Alytes is indexed in the following data ba

Current Awareness in Biological Scien,

Imprimerie F. Paillart, Abbeville, France.

Dépôt légal: 2°" trimestre 1991.

Source : MNHN, Paris: