Papers on amphibian decline
Posted by Ari Jokimäki on August 3, 2011
This is a list of papers on recent decline and extinctions in amphibian populations. The list is not complete, and will most likely be updated in the future in order to make it more thorough and more representative.
UPDATE (August 4, 2011): Anchukaitis & Evans (2010) [pointed out to me in Twitter by Kevin Anchukaitis] Duarte et al. (2011) [was published today] added.
Can amphibians take the heat? Vulnerability to climate warming in subtropical and temperate larval amphibian communities – Duarte et al. (2011) “Predicting the biodiversity impacts of global warming implies we know where and with what magnitude these impacts will be encountered. Amphibians are currently the most threatened vertebrates, mainly due to habitat loss and to emerging infectious diseases. Global warming may further exacerbate their decline in the near future, although the impact might vary geographically. We predicted that subtropical amphibians should be relatively susceptible to warming induced extinctions because their upper critical thermal limits (CTmax) might be only slightly higher than maximum pond temperatures (Tmax). We tested this prediction by measuring CTmax and Tmax for 47 larval amphibian species from two thermally distinct subtropical communities (the warm community of the Gran Chaco and the cool community of Atlantic Forest, northern Argentina), as well as from one European temperate community. Upper thermal tolerances of tadpoles were positively correlated (controlling for phylogeny) with maximum pond temperatures, although the slope was steeper in subtropical than in temperate species. CTmax values were lowest in temperate species and highest in the subtropical warm community, which paradoxically, had very low warming tolerance (CTmax – Tmax) and therefore may be prone to future local extinction from acute thermal stress if rising pond Tmax soon exceeds their CTmax. Canopy protected subtropical cool species have larger warming tolerance and thus should be less impacted by peak temperatures. Temperate species are relatively secure to warming impacts, except for late breeders with low thermal tolerance which may be exposed to physiological thermal stress in the coming years.” Helder Duarte, Miguel Tejedo, Marco Katzenberger, Federico Marangoni, Diego Baldo, Juan Francisco Beltrán, Dardo Andrea Martí, Alex Richter-Boix, Alejandro Gonzalez-Voyer, Global Change Biology, DOI: 10.1111/j.1365-2486.2011.02518.x.
Citation Rate and Perceived Subject Bias in the Amphibian-Decline Literature – Ohmer & Bishop (2011) “As a result of global declines in amphibian populations, interest in the conservation of amphibians has grown. This growth has been fueled partially by the recent discovery of other potential causes of declines, including chytridiomycosis (the amphibian chytrid, an infectious disease) and climate change. It has been proposed that researchers have shifted their focus to these novel stressors and that other threats to amphibians, such as habitat loss, are not being studied in proportion to their potential effects. We tested the validity of this proposal by reviewing the literature on amphibian declines, categorizing the primary topic of articles within this literature (e.g., habitat loss or UV-B radiation) and comparing citation rates among articles on these topics and impact factors of journals in which the articles were published. From 1990 to 2009, the proportion of papers on habitat loss remained fairly constant, and although the number of papers on chytridiomycosis increased after the disease was described in 1998, the number of published papers on amphibian declines also increased. Nevertheless, papers on chytridiomycosis were more highly cited than papers not on chytridiomycosis and were published in journals with higher impact factors on average, which may indicate this research topic is more popular in the literature. Our results were not consistent with a shift in the research agenda on amphibians. We believe the perception of such a shift has been supported by the higher citation rates of papers on chytridiomycosis.” Michel E. Ohmer, Phillip J. Bishop, Conservation Biology, Volume 25, Issue 1, pages 195–199, February 2011, DOI: 10.1111/j.1523-1739.2010.01591.x. [Full text, Supporting information Note that SI has a spreadsheet with references to about 1500 papers on the subject!]
Amphibian decline and extinction: What we know and what we need to learn – Collins (2010) “For over 350 million yr, thousands of amphibian species have lived on Earth. Since the 1980s, amphibians have been disappearing at an alarming rate, in many cases quite suddenly. What is causing these declines and extinctions? In the modern era (post 1500) there are 6 leading causes of biodiversity loss in general, and all of these acting alone or together are responsible for modern amphibian declines: commercial use; introduced/exotic species that compete with, prey on, and parasitize native frogs and salamanders; land use change; contaminants; climate change; and infectious disease. The first 3 causes are historical in the sense that they have been operating for hundreds of years, although the rate of change due to each accelerated greatly after about the mid-20th century. Contaminants, climate change, and emerging infectious diseases are modern causes suspected of being responsible for the so-called ‘enigmatic decline’ of amphibians in protected areas. Introduced/exotic pathogens, land use change, and infectious disease are the 3 causes with a clear role in amphibian decline as well as extinction; thus far, the other 3 causes are only implicated in decline and not extinction. The present work is a review of the 6 causes with a focus on pathogens and suggested areas where new research is needed. Batrachochytrium dendrobatidis (Bd) is a chytrid fungus that is an emerging infectious disease causing amphibian population decline and species extinction. Historically, pathogens have not been seen as a major cause of extinction, but Bd is an exception, which is why it is such an interesting, important pathogen to understand. The late 20th and early 21st century global biodiversity loss is characterized as a sixth extinction event. Amphibians are a striking example of these losses as they disappear at a rate that greatly exceeds historical levels. Consequently, modern amphibian decline and extinction is a lens through which we can view the larger story of biodiversity loss and its consequences.” James P. Collins, Dis Aquat Org 92:93-99, doi:10.3354/dao02307.
Tropical cloud forest climate variability and the demise of the Monteverde golden toad – Anchukaitis & Evans (2010) “Widespread amphibian extinctions in the mountains of the American tropics have been blamed on the interaction of anthropogenic climate change and a lethal pathogen. However, limited meteorological records make it difficult to conclude whether current climate conditions at these sites are actually exceptional in the context of natural variability. We use stable oxygen isotope measurements from trees without annual rings to reconstruct a century of hydroclimatology in the Monteverde Cloud Forest of Costa Rica. High-resolution measurements reveal coherent isotope cycles that provide annual chronological control and paleoclimate information. Climate variability is dominated by interannual variance in dry season moisture associated with El Niño Southern Oscillation events. There is no evidence of a trend associated with global warming. Rather, the extinction of the Monteverde golden toad (Bufo periglenes) appears to have coincided with an exceptionally dry interval caused by the 1986–1987 El Niño event.” Kevin J. Anchukaitis and Michael N. Evans, PNAS March 16, 2010 vol. 107 no. 11 5036-5040, doi: 10.1073/pnas.0908572107. [Full text]
Global Amphibian Extinction Risk Assessment for the Panzootic Chytrid Fungus – Rödder et al. (2009) “Species are being lost at increasing rates due to anthropogenic effects, leading to the recognition that we are witnessing the onset of a sixth mass extinction. Emerging infectious disease has been shown to increase species loss and any attempts to reduce extinction rates need to squarely confront this challenge. Here, we develop a procedure for identifying amphibian species that are most at risk from the effects of chytridiomycosis by combining spatial analyses of key host life-history variables with the pathogen’s predicted distribution. We apply our rule set to the known global diversity of amphibians in order to prioritize pecies that are most at risk of loss from disease emergence. This risk assessment shows where limited conservation funds are best deployed in order to prevent further loss of species by enabling ex situ amphibian salvage operations and focusing any potential disease mitigation projects.” Dennis Rödder, Jos Kielgast, Jon Bielby, Sebastian Schmidtlein, Jaime Bosch, Trenton W. J. Garner, Michael Veith, Susan Walker, Matthew C. Fisher and Stefan Lötters, Diversity 2009, 1(1), 52-66; doi:10.3390/d1010052. [Full text]
Chytridiomycosis, Amphibian Extinctions, and Lessons for the Prevention of Future Panzootics – Kriger & Hero (2009) “The human-mediated transport of infected amphibians is the most plausible driver for the intercontinental spread of chytridiomycosis, a recently emerged infectious disease responsible for amphibian population declines and extinctions on multiple continents. Chytridiomycosis is now globally ubiquitous, and it cannot be eradicated from affected sites. Its rapid spread both within and between continents provides a valuable lesson on preventing future panzootics and subsequent erosion of biodiversity, not only of amphibians, but of a wide array of taxa: the continued inter-continental trade and transport of animals will inevitably lead to the spread of novel pathogens, followed by numerous extinctions. Herein, we define and discuss three levels of amphibian disease management: (1) post-exposure prophylactic measures that are curative in nature and applicable only in a small number of situations; (2) pre-exposure prophylactic measures that reduce disease threat in the short-term; and (3) preventive measures that remove the threat altogether. Preventive measures include a virtually complete ban on all unnecessary long-distance trade and transport of amphibians, and are the only method of protecting amphibians from disease-induced declines and extinctions over the long-term. Legislation to prevent the emergence of new diseases is urgently required to protect global amphibian biodiversity.” Kerry M. Kriger and Jean-Marc Hero, EcoHealth, Volume 6, Number 1, 6-10, DOI: 10.1007/s10393-009-0228-y. [Full text]
Are we in the midst of the sixth mass extinction? A view from the world of amphibians – Wake & Vredenburg (2008) “Many scientists argue that we are either entering or in the midst of the sixth great mass extinction. Intense human pressure, both direct and indirect, is having profound effects on natural environments. The amphibians—frogs, salamanders, and caecilians—may be the only major group currently at risk globally. A detailed worldwide assessment and subsequent updates show that one-third or more of the 6,300 species are threatened with extinction. This trend is likely to accelerate because most amphibians occur in the tropics and have small geographic ranges that make them susceptible to extinction. The increasing pressure from habitat destruction and climate change is likely to have major impacts on narrowly adapted and distributed species. We show that salamanders on tropical mountains are particularly at risk. A new and significant threat to amphibians is a virulent, emerging infectious disease, chytridiomycosis, which appears to be globally distributed, and its effects may be exacerbated by global warming. This disease, which is caused by a fungal pathogen and implicated in serious declines and extinctions of >200 species of amphibians, poses the greatest threat to biodiversity of any known disease. Our data for frogs in the Sierra Nevada of California show that the fungus is having a devastating impact on native species, already weakened by the effects of pollution and introduced predators. A general message from amphibians is that we may have little time to stave off a potential mass extinction.” David B. Wake and Vance T. Vredenburg, PNAS August 12, 2008 vol. 105 no. Supplement 1 11466-11473, doi: 10.1073/pnas.0801921105. [Full text]
Evaluating the links between climate, disease spread, and amphibian declines – Rohr et al. (2008) “Human alteration of the environment has arguably propelled the Earth into its sixth mass extinction event and amphibians, the most threatened of all vertebrate taxa, are at the forefront. Many of the worldwide amphibian declines have been caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd), and two contrasting hypotheses have been proposed to explain these declines. Positive correlations between global warming and Bd-related declines sparked the chytrid-thermal-optimum hypothesis, which proposes that global warming increased cloud cover in warm years that drove the convergence of daytime and nighttime temperatures toward the thermal optimum for Bd growth. In contrast, the spatiotemporal-spread hypothesis states that Bd-related declines are caused by the introduction and spread of Bd, independent of climate change. We provide a rigorous test of these hypotheses by evaluating (i) whether cloud cover, temperature convergence, and predicted temperature-dependent Bd growth are significant positive predictors of amphibian extinctions in the genus Atelopus and (ii) whether spatial structure in the timing of these extinctions can be detected without making assumptions about the location, timing, or number of Bd emergences. We show that there is spatial structure to the timing of Atelopus spp. extinctions but that the cause of this structure remains equivocal, emphasizing the need for further molecular characterization of Bd. We also show that the reported positive multi-decade correlation between Atelopus spp. extinctions and mean tropical air temperature in the previous year is indeed robust, but the evidence that it is causal is weak because numerous other variables, including regional banana and beer production, were better predictors of these extinctions. Finally, almost all of our findings were opposite to the predictions of the chytrid-thermal-optimum hypothesis. Although climate change is likely to play an important role in worldwide amphibian declines, more convincing evidence is needed of a causal link.” Jason R. Rohr, Thomas R. Raffel, John M. Romansic, Hamish McCallum, and Peter J. Hudson, PNAS November 11, 2008 vol. 105 no. 45 17436-17441, doi: 10.1073/pnas.0806368105. [Full text]
Life-history trade-offs influence disease in changing climates: strategies of an amphibian pathogen – Woodhams et al. (2008) “Life-history trade-offs allow many animals to maintain reproductive fitness across a range of climatic conditions. When used by parasites and pathogens, these strategies may influence patterns of disease in changing climates. The chytrid fungus, Batrachochytrium dendrobatidis, is linked to global declines of amphibian populations. Short-term growth in culture is maximal at 17°–25°C. This has been used in an argument that global warming, which increases the time that amphibians spend at these temperatures in cloud-covered montane environments, has led to extinctions. Here we show that the amphibian chytrid responds to decreasing temperatures with trade-offs that increase fecundity as maturation rate slows and increase infectivity as growth decreases. At 17°–25°C, infectious zoospores encyst (settle and develop a cell wall) and develop into the zoospore-producing stage (zoosporangium) faster, while at 7°–10°C, greater numbers of zoospores are produced per zoosporangium; these remain infectious for a longer period of time. We modeled the population growth of B. dendrobatidis through time at various temperatures using delayed differential equations and observational data for four parameters: developmental rate of thalli, fecundity, rate of zoospore encystment, and rate of zoospore survival. From the models, it is clear that life-history trade-offs allow B. dendrobatidis to maintain a relatively high long-term growth rate at low temperatures, so that it maintains high fitness across a range of temperatures. When a seven-day cold shock is simulated, the outcome is intermediate between the two constant temperature regimes, and in culture, a sudden drop in temperature induces zoospore release. These trade-offs can be ecologically important for a variety of organisms with complex life histories, including pathogenic microorganisms. The effect of temperature on amphibian mortality will depend on the interaction between fungal growth and host immune function and will be modified by host ecology, behavior, and life history. These results demonstrate that B. dendrobatidis populations can grow at high rates across a broad range of environmental temperatures and help to explain why it is so successful in cold montane environments.” Woodhams, Douglas C., Ross A. Alford, Cheryl J. Briggs, Megan Johnson, and Louise A. Rollins-Smith. 2008, Ecology 89:1627–1639. [doi:10.1890/06-1842.1]. [Full text]
Measuring the Meltdown: Drivers of Global Amphibian Extinction and Decline – Sodhi et al. (2008) “Habitat loss, climate change, over-exploitation, disease and other factors have been hypothesised in the global decline of amphibian biodiversity. However, the relative importance of and synergies among different drivers are still poorly understood. We present the largest global analysis of roughly 45% of known amphibians (2,583 species) to quantify the influences of life history, climate, human density and habitat loss on declines and extinction risk. Multi-model Bayesian inference reveals that large amphibian species with small geographic range and pronounced seasonality in temperature and precipitation are most likely to be Red-Listed by IUCN. Elevated habitat loss and human densities are also correlated with high threat risk. Range size, habitat loss and more extreme seasonality in precipitation contributed to decline risk in the 2,454 species that declined between 1980 and 2004, compared to species that were stable (n=1,545) or had increased (n=28). These empirical results show that amphibian species with restricted ranges should be urgently targeted for conservation.” Navjot S. Sodhi, David Bickford, Arvin C. Diesmos, Tien Ming Lee, Lian Pin Koh, Barry W. Brook, Cagan H. Sekercioglu, and Corey J. A. Bradshaw, PLoS ONE. 2008; 3(2): e1636, doi: 10.1371/journal.pone.0001636. [Full text]
Global warming and amphibian extinctions in eastern Australia – Laurance (2008) “Pounds et al. recently argued that the dramatic, fungal pathogen-linked extinctions of numerous harlequin frogs (Atelopus spp.) in upland rainforests of South America mostly occurred immediately following exceptionally warm years, implicating global warming as a likely trigger for these extinctions. I tested this hypothesis using temperature data for eastern Australia, where at least 14 upland-rainforest frog species have also experienced extinctions or striking population declines attributed to the same fungal pathogen, and where temperatures have also risen significantly in recent decades. My analyses provide little direct support for the warm-year hypothesis of Pounds et al., although my statistical power to detect effects of small (0.5°C) temperature increases was limited. However, I found stronger support for a modified version of the warm-year hypothesis, whereby frog declines were likely to occur following three consecutive years of unusually warm weather. This trend was apparent only at tropical latitudes, where rising minimum temperatures were greatest. Although much remains uncertain, my findings appear consistent with the notion that global warming could predispose some upland amphibian populations to virulent pathogens.” William F. Laurance, Austral Ecology, Volume 33, Issue 1, pages 1–9, February 2008, DOI: 10.1111/j.1442-9993.2007.01812.x. [Full text]
Riding the Wave: Reconciling the Roles of Disease and Climate Change in Amphibian Declines – Lips et al. (2008) “We review the evidence for the role of climate change in triggering disease outbreaks of chytridiomycosis, an emerging infectious disease of amphibians. Both climatic anomalies and disease-related extirpations are recent phenomena, and effects of both are especially noticeable at high elevations in tropical areas, making it difficult to determine whether they are operating separately or synergistically. We compiled reports of amphibian declines from Lower Central America and Andean South America to create maps and statistical models to test our hypothesis of spatiotemporal spread of the pathogen Batrachochytrium dendrobatidis (Bd), and to update the elevational patterns of decline in frogs belonging to the genus Atelopus. We evaluated claims of climate change influencing the spread of Bd by including error into estimates of the relationship between air temperature and last year observed. Available data support the hypothesis of multiple introductions of this invasive pathogen into South America and subsequent spread along the primary Andean cordilleras. Additional analyses found no evidence to support the hypothesis that climate change has been driving outbreaks of amphibian chytridiomycosis, as has been posited in the climate-linked epidemic hypothesis. Future studies should increase retrospective surveys of museum specimens from throughout the Andes and should study the landscape genetics of Bd to map fine-scale patterns of geographic spread to identify transmission routes and processes.” Karen R. Lips, Jay Diffendorfer, Joseph R. Mendelson III, Michael W. Sears, PLoS Biol 6(3): e72. doi:10.1371/journal.pbio.0060072. [Full text]
Amphibian Decline or Extinction? Current Declines Dwarf Background Extinction Rate – McCallum (2007) “Amphibian declines and extinctions are critical concerns of biologists around the world. The estimated current rate of amphibian extinction is known, but how it compares to the background amphibian extinction rate from the fossil record has not been well studied. I compared current amphibian extinction rates with their reported background extinction rates using standard and fuzzy arithmetic. These calculations suggest that the current extinction rate of amphibians could be 211 times the background amphibian extinction rate. If current estimates of amphibian species in imminent danger of extinction are included in these calculations, then the current amphibian extinction rate may range from 25,039–45,474 times the background extinction rate for amphibians. It is difficult to explain this unprecedented and accelerating rate of extinction as a natural phenomenon.” Malcolm L. McCallum, Journal of Herpetology 41(3):483-491. 2007, doi: 10.1670/0022-1511(2007)41[483:ADOECD]2.0.CO;2. [Full text]
Spread of Chytridiomycosis Has Caused the Rapid Global Decline and Extinction of Frogs – Skerratt et al. (2007) “The global emergence and spread of the pathogenic, virulent, and highly transmissible fungus Batrachochytrium dendrobatidis, resulting in the disease chytridiomycosis, has caused the decline or extinction of up to about 200 species of frogs. Key postulates for this theory have been completely or partially fulfilled. In the absence of supportive evidence for alternative theories despite decades of research, it is important for the scientific community and conservation agencies to recognize and manage the threat of chytridiomycosis to remaining species of frogs, especially those that are naive to the pathogen. The impact of chytridiomycosis on frogs is the most spectacular loss of vertebrate biodiversity due to disease in recorded history.” Lee Francis Skerratt, Lee Berger, Richard Speare, Scott Cashins, Keith Raymond McDonald, Andrea Dawn Phillott, Harry Bryan Hines and Nicole Kenyon, EcoHealth, Volume 4, Number 2, 125-134, DOI: 10.1007/s10393-007-0093-5. [Full text]
Widespread amphibian extinctions from epidemic disease driven by global warming – Pounds et al. (2006) “As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog (Atelopus sp.) vanished along with the golden toad (Bufo periglenes). An estimated 67% of the 110 or so species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with ‘very high confidence’ (> 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable.” J. Alan Pounds, Martín R. Bustamante, Luis A. Coloma, Jamie A. Consuegra, Michael P. L. Fogden, Pru N. Foster, Enrique La Marca, Karen L. Masters, Andrés Merino-Viteri, Robert Puschendorf, Santiago R. Ron, G. Arturo Sánchez-Azofeifa, Christopher J. Still & Bruce E. Young, Nature 439, 161-167 (12 January 2006) | doi:10.1038/nature04246. [Full text]
Emerging infectious disease and the loss of biodiversity in a Neotropical amphibian community – Lips et al. (2006) “Pathogens rarely cause extinctions of host species, and there are few examples of a pathogen changing species richness and diversity of an ecological community by causing local extinctions across a wide range of species. We report the link between the rapid appearance of a pathogenic chytrid fungus Batrachochytrium dendrobatidis in an amphibian community at El Copé, Panama, and subsequent mass mortality and loss of amphibian biodiversity across eight families of frogs and salamanders. We describe an outbreak of chytridiomycosis in Panama and argue that this infectious disease has played an important role in amphibian population declines. The high virulence and large number of potential hosts of this emerging infectious disease threaten global amphibian diversity.” Karen R. Lips, Forrest Brem, Roberto Brenes, John D. Reeve, Ross A. Alford, Jamie Voyles, Cynthia Carey, Lauren Livo, Allan P. Pessier, and James P. Collins, PNAS February 28, 2006 vol. 103 no. 9 3165-3170, doi: 10.1073/pnas.0506889103. [Full text]
Species Review of Amphibian Extinction Risks in Madagascar: Conclusions from the Global Amphibian Assessment – Andreone et al. (2005) “We assessed the extinction risks of Malagasy amphibians by evaluating their distribution, occurrence in protected areas, population trends, habitat quality, and prevalence in commercial trade. We estimated and mapped the distribution of each of the 220 described Malagasy species and applied, for the first time, the IUCN Red List categories and criteria to all species described at the time of the assessment. Nine species were categorized as critically endangered, 21 as endangered, and 25 as vulnerable. The most threatened species occur on the High Plateau and/or have been subjected to overcollection for the pet trade, but restricted extent of occurrence and ongoing habitat destruction were identified as the most important factors influencing extinction threats. The two areas with the majority of threatened species were the northern Tsaratanana-Marojejy-Masoala highlands and the southeastern Anosy Mountains. The current system of protected areas includes 82% of the threatened amphibian species. Of the critically endangered species, 6 did not occur in any protected area. For conservation of these species we recommend the creation of a reserve for the species of the Mantella aurantiaca group, the inclusion of two Scaphiophryne species in the Convention on the International Trade in Endangered Species Appendix II, and the suspension of commercial collecting for Mantella cowani. Field surveys during the last 15 years reveal no pervasive extinction of Malagasy amphibians resulting from disease or other agents, as has been reported in some other areas of the world.” Franco Andreone, John E. Cadle, Neil Cox, Frank Glaw, Ronald A. Nussbaum, Christopher J. Raxworthy, Simon N. Stuart, Denis Vallan, Miguel Vences, Conservation Biology, Volume 19, Issue 6, pages 1790–1802, December 2005, DOI: 10.1111/j.1523-1739.2005.00249.x. [Full text]
Status and Trends of Amphibian Declines and Extinctions Worldwide – Stuart et al. (2004) “The first global assessment of amphibians provides new context for the well-publicized phenomenon of amphibian declines. Amphibians are more threatened and are declining more rapidly than either birds or mammals. Although many declines are due to habitat loss and overutilization, other, unidentified processes threaten 48% of rapidly declining species and are driving species most quickly to extinction. Declines are nonrandom in terms of species’ ecological preferences, geographic ranges, and taxonomic associations and are most prevalent among Neotropical montane, stream-associated species. The lack of conservation remedies for these poorly understood declines means that hundreds of amphibian species now face extinction.” Simon N. Stuart, Janice S. Chanson, Neil A. Cox, Bruce E. Young, Ana S. L. Rodrigues, Debra L. Fischman and Robert W. Waller, Science 3 December 2004: Vol. 306 no. 5702 pp. 1783-1786, DOI: 10.1126/science.1103538. [Full text]
Chytridiomycosis causes amphibian mortality associated with population declines in the rain forests of Australia and Central America – Berger et al. (1998) “Epidermal changes caused by a chytridiomycete fungus (Chytridiomycota; Chytridiales) were found in sick and dead adult anurans collected from montane rain forests in Queensland (Australia) and Panama during mass mortality events associated with significant population declines. We also have found this new disease associated with morbidity and mortality in wild and captive anurans from additional locations in Australia and Central America. This is the first report of parasitism of a vertebrate by a member of the phylum Chytridiomycota. Experimental data support the conclusion that cutaneous chytridiomycosis is a fatal disease of anurans, and we hypothesize that it is the proximate cause of these recent amphibian declines.” Lee Berger, Rick Speare, Peter Daszak, D. Earl Green, Andrew A. Cunningham, C. Louise Goggin, Ron Slocombe, Mark A. Ragan, Alex D. Hyatt, Keith R. McDonald, Harry B. Hines, Karen R. Lips, Gerry Marantelli, and Helen Parkes, PNAS July 21, 1998 vol. 95 no. 15 9031-9036. [Full text]
Amphibian Declines: Judging Stability, Persistence, and Susceptibility of Populations to Local and Global Extinctions – Blaustein et al. (1994) “Extinctions are normal biological phenomena. Both mass extinctions in geological time and local extinctions in ecological time are well documented, but rates of extinction have increased in recent years – especially in vertebrates, including amphibians – as illustrated by recent reports of their population declines and range reductions. We suggest that long-term population data are necessary for rigorously evaluating the significance of the amphibian declines. Due to the physiological constraints, relatively low mobility, and site fidelity of amphibians, we suggest that many amphibian populations may be unable to recolonize areas after local extinction.” Andrew R. Blaustein, David B. Wake and Wayne P. Sousa, Conservation Biology, Vol. 8, No. 1 (Mar., 1994), pp. 60-71. [Full text]