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Society for Conservation Biology 16th
Annual Meeting July 14-July 19 2002
co-hosted by DICE and the British Ecological Society
Abstracts for Symposium Fourteen
Global amphibian declines: is current research
meeting conservation needs?
Cornwallis Lecture Theatre 1
Monday 15th July: 10.15 - 12.15
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(BLOCK CAPITALS indicate the presenting author)
10.15 - 10.30
HALLIDAY, TIM. Department of Biological Sciences, The Open University, Milton
Keynes, MK7 6AA, UK.
<t.r.halliday@open.ac.uk>
AMPHIBIAN POPULATION DECLINES: THEIR WIDER SIGNIFICANCE FOR CONSERVATION BIOLOGY
Dramatic population declines among many amphibians around the world, some leading
to species extinctions, were first noted in 1989 and many have occurred in protected
areas. This raises serious doubts about the effectiveness of habitat protection as
a conservation strategy. Initially, there was an implicit assumption that amphibian
population declines were caused by a single, unknown factor. The search for a 'smoking
gun' has revealed, however, that many factors are responsible for amphibian declines
and that most well-studied declines are due to complex synergistic effects between
several factors. None of the factors identified is uniquely applicable to amphibians.
Of particular concern is the possibility that amphibians may have become more susceptible
to infectious diseases as a result of various kinds of environmental change. Amphibians
are good indicators for certain kinds of freshwater habitat and their widespread
decline suggests that the world's freshwater resources are currently under particularly
severe threat.
10.30 - 10.45
SCHMIDT, BENEDIKT R., Zoology Institute, University of Zurich, Winterthurerstrasse
190, CH-8057 Zurich, Switzerland, <bschmidt@zool.unizh.ch>
DYNAMICS AND DEMOGRAPHY OF AMPHIBIANS: THE PITFALLS OF COUNT DATA FOR POPULATION
ASSESSMENT
Amphibian populations are declining for a variety of reasons. The sizes of populations
are getting smaller and populations go extinct locally and regionally. The evidence
for declining population sizes, the underlying demography, and for local and regional
extinctions is usually based on count data. Count data are not reliable even when
collected using standardized methods. A simple formula relates count data to the
true demography, population size, or distribution: C = Np, where C is a count, N
the true parameter value, and p is a capture or detection probability. With count
data, one assumes a) that there is a positive and linear relationship between C and
N and b) that p is constant in time and space. These assumptions are unlikely to
be met in field studies of amphibian declines, monitoring programs, or assessment
of important populations for conservation. In conclusion, the data that is being
used for conservation biology and conservation action is rather weak. Demography,
dynamics and distributions of amphibians should be based on methods that account
for capture probabilities (p) that may vary temporally and spatially, i.e. capture
recapture methods.
10.45 - 11.00
SJÖGREN-GULVE, PER, Department of Conservation Biology & Genetics, EBC,
Norbyv. 18D, SE-752 36 Uppsala, Sweden, and the Swedish Environmental Protection
Agency, SE-106 48 Stockholm, Sweden <per.sjogren-gulve@environ.se>
TOO MUCH OR NOT ENOUGH METAPOPULATION CONSIDERATION IN AMPHIBIAN CONSERVATION?
Metapopulation theory has become popular in conservation biology, but its utility
in conservation is questioned as well. Many papers and textbook chapters focus on
metapopulation models that are illustrative on theoretical grounds, but not useful
in the real world because their assumptions are not met. For the pool frog (Rana
lessonae) in Sweden, a metapopulation approach to conservation seems justified.
Since the first inventory of the species published by Forselius in 1962, 60 local
extinctions have occurred, and 45 (re)colonizations occurred during 1983-2001. Only
during 1994-2001, 25 extinctions and 22 (re)colonizations were noted among the 96
local populations. Thus, a landscape approach is necessary for their conservation.
Using simple pond and landscape variables selected by logistic regression analyses
of population turnover during the 1980s, a metapopulation model correctly classified
80 out of 102 ponds as being occupied by the pool frog in 2001. The statistical analyses
highlighted environmental aspects that seem important for local and regional persistence,
and the simulation modelling added further understanding. My conclusion is that landscape
and metapopulation aspects of amphibian conservation have just begun to gain the
attention they deserve, and that use of appropriate models will help further in this
important work.
11.00 - 11.15
HERO, JEAN-MARC Endangered Frog Research Centre, School of Environmental and
Applied Sciences, Griffith University, PMB 50 Gold Coast Mail Centre, QLD 9726 Australia.
(m.hero@mailbox.gu.edu.au)
MANAGING AMPHIBIAN DECLINES IN AUSTRALIA: GLOBAL IMPLICATIONS
Amphibian biodiversity and their threats are not uniformly distributed over latitudinal
and altitudinal gradients. Biodiversity is concentrated in tropical countries, where
loss of habitat is continuing at a rapid rate, particularly at low altitudes. These
threats are compounded by unexplained declines recorded in high altitude populations
where no direct anthropogenic impacts are evident. In Australia threatened amphibians
(IUCN Global Amphibian Assessment 2001) fall into two distinct groups. For the 25
high conservation risk species (Endangered, Critically Endangered or Extinct) most
(84%) occupy upland areas (>300m asl), habitat loss is directly linked to declines
in 10 species (40%), mysterious declines are associated with 15 species (60%) and
disease associated with 11 species (44%). For the 19 lower conservation risk species
(Vulnerable and Near Threatened) the majority (68%) occupy lowland areas, habitat
loss is directly linked to declines in 12 species (63%), none have declined mysteriously
and disease has been associated with only 4 species (21%). Conservation priorities
vary considerably for each group. Here I will discuss the characteristics of amphibians
associated with extinction in Australia and evaluate the causes and potential solutions.
Finally I propose a management framework to combat global amphibian declines.
11.15 - 11.30
COLLINS, JAMES P. Department of Biology, Arizona State University, Tempe, AZ,
USA, 85287-1501, (jcollins@asu.edu).
EMERGING WILDLIFE DISEASES AND AMPHIBIAN BIODIVERSITY
Understanding the causes and consequences of Earth’s diminishing biodiversity and
understanding the ecology and evolution of infectious diseases are two major challenges
in environmental sciences. Two amphibian pathogens, a ranavirus and a chytrid fungus,
are suspected causes of global amphibian declines. At the center of these challenges
is the question, "Why are pathogens causing some amphibian populations to decline,
even to extinction?" Three years ago some 24 investigators from the U.S.A.,
Canada, and Australia formed a research team to answer a series of questions related
to host-pathogen biology and global amphibian declines. Our results indicate that
pathogens are one among several likely causes of declines. Both ranavirus and chytrid
fungus vary among species in their virulence, may directly or indirectly affect amphibian
performance, and differ in their effects depending on life history stage. Ranavirus
and chytrid phylogeographic studies both suggest recent and possibly human-related
spread. Our research group is integrating diverse disciplines in ways that are advancing
our understanding of basic host-pathogen biology, especially as it relates to amphibian
declines, a key example of the general loss of biodiversity.
11.30 - 11.45
DASZAK, PETER, Brady Porter, Jess Morgan, Rolando Mazzoni, Andrew A. Cunningham,
Ann Strieby, Joyce E. Longcore, and David Porter. Consortium for Conservation Medicine,
Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades,
NY 10964, USA <daszak@conservationmedicine.org> (PD), Dept Genetics, University
of Georgia, Athens, USA (BP), Dept Biol., University of New Mexico, USA (JM), Inst.
Invest. Pesqueras, Montevideo 11300, Uruguay (RM), Institute of Zoology, Regent’s
Park, London NW1 4RY, UK (AAC), College of Vet Medicine, University of Georgia, Athens,
USA (AS), Dept. Biol. Sci., University of Maine, Orono, Maine 04469, USA (JEL) and
Dept Botany, University of Georgia, Athens, USA (DP)
PATHOGEN POLLUTION AND GLOBAL AMPHIBIAN DECLINES
Fungal and viral pathogens have been implicated in the global decline of amphibian
populations. In particular an emerging fungal disease, chytridiomycosis, is associated
with mass mortality events and population declines in a range of tropical and temperate
species. We present results from a range of studies that assess the underlying environmental
driver of chytridiomycosis, including phylogenetic analysis of DNA sequences from
the Internally Transcribed Spacer (ITS) region of over 30 isolates of the causative
agent, Batrachochytrium dendrobatidis. Sequences from North, Central, South
America and Australia were highly conserved and in some cases identical, suggesting
recent mixing between populations. These data implicate anthropogenic introduction
of pathogens and/or hosts ("pathogen pollution") as a driver of disease
emergence. We have detected chytridiomycosis in animals associated with the international
pet, food and lab animal trades and from animals introduced as garden pond species
and biocontrol agents. Our preliminary data suggest that bullfrogs (Rana catesbeiana)
are relatively resistant to chytridiomycosis and may therefore be efficient carrier
hosts. This species is bred in large open-plan farms in South America and Asia the
global trade in frog legs as a food item. We suggest surveillance and control measures
to prevent future pathogen pollution within these trades.
11.45 - 12.00
FOSTER, JIM P. and Trevor J.C. Beebee. English Nature, Northminster House, Peterborough
PE1 1UA, UK, <jim.foster@english-nature.org.uk> (JPF) and School of Biological
Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK (TJCB).
USING RESEARCH TO INFORM UK AMPHIBIAN CONSERVATION POLICY
In the UK, research has assisted by improving our understanding of amphibian populations,
their habitats, threats, and the effectiveness of conservation measures. The greatest
research effort has been directed to the protected and declining species, notably
Triturus cristatus, Bufo calamita and Rana lessonae. However,
several challenges arise when attempting to employ research findings as a tool to
shape policy. Often, wild populations and threats to them are not simple systems
that invite straightforward investigation. Extrapolating from small studies to more
comprehensive application can also generate problems, especially with widespread
species. The standards of confidence commonly used in science may not be directly
transferable to conservation policy, as in conservation it is often desirable to
apply the precautionary principle. When constructing policies, it is important to
be realistic about the constraints which may be imposed due to factors beyond the
control of conservation agencies, notably those of a legislative or socio-economic
nature. There is a need for conservation practitioners to engage more closely with
scientists, with a view to identifying the current knowledge gaps that hinder the
achievement of conservation gains. The increasing success of B. calamita reintroductions
provides an excellent illustration of such an application of scientific knowledge.
12.00 - 12.15
Discussion
The SCB2002 pages are maintained by Christine Eagle
email: C.M.Eagle@ukc.ac.uk
Conference email: scb2002@ukc.ac.uk
Last updated: 30.06.02