Book chapter
Chapter 8: Assessing the physiological sensitivity of amphibians to extreme environmental change using the stress endocrine responses
Amphibian and Reptile Adaptations to the Environment: Interplay Between Physiology and Behavior, pp.189-208
CRC Press, 1
2016
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Abstract
Amphibians are excellent bioindicators of environmental health, and being ectothermic animals, their day-day life-history traits are influenced by both short- and long-term changes in environmental temperature (Beebee and Griffiths 2005). Unfortunately, the population of various amphibian species have started to decline around the world and many species have already become extinct or have been placed on the International Union for Conservation of Nature (IUCN) endangered species list. Since 1980, declines in certain amphibian populations have occurred worldwide (Crump et al. 1992). In 2004, amphibian biologists at an international conference announced that 32% of amphibian species are currently threatened, the population of 44% of species are in a decline, and 120 amphibian species have likely become extinct only in the last 25 years (Stuart et al. 2004). Factors such as habitat loss and deterioration, global warming, ultraviolet light, acid rain, commercial collection, invasive species, and pesticide use have all been investigated and implicated as causes for these declines in amphibian populations. Global amphibian populations are declining rapidly toward extinction and scientists have begun analysis of past declines to make predictions about future declines based on complex climatic models (Bosch et al. 2007; Raffel et al. 2012), with predictions made that anthropogenic-induced climate change continues to have huge impacts on amphibian populations worldwide. Furthermore, the additional impacts of pathogenic diseases and other human-induced factors, such as habitat destruction and urbanization are making amphibian population declines even more catastrophic. Global mean temperatures have risen by approximately 0.74°C over the past 100 years with the Fourth Intergovernmental Panel on Climate Change (IPCC) reports predicting that without intervention, this trend will continue (Root et al. 2003; Parmesan 2006; IPCC 2007a). By the end of this century, global temperatures are predicted to increase by 1.8-4°C, with higher latitudes having the greatest warming (IPCC 2007b). It is predicted that climate change will cause major environmental and economic impacts, particularly from increases in the frequency of extreme weather events such as bushfire, droughts, floods, and heat waves, for example, in Australia (Hughes 2003; IPCC 2007a,b). It is plausible that greater frequency of extreme changes in global climate within the last 50 years has led to rapid amphibian declines (Alexander and Eischeid 2001; Beebee and Griffiths 2005). Possible evidence of this decline is validated by the golden toad (Incilius periglenes), which has not been seen in the Costa Rican rainforest since the early 1980s (Pounds et al. 1997; Beebee and Griffiths 2005). I. periglenes was found in the higher altitudes of the mountains, and species restricted to lower altitudes have since then moved higher into the mountains (Wake and Vredenburg 2008). A major concern associated with global climate change is that with a relatively large number of frogs and lizards identified as high-elevation specialists, species restricted to higher altitudes have nowhere to go in response to extreme variation in environmental temperature. Even for lowland species, possible areas of dispersal in response to anthropogenic-induced climate change are constantly affected by the processes associated with habitat loss and fragmentation (Pearson and Dawson 2005; Nystrom et al. 2007; Laurance et al. 2011). However, climate variability could also contribute to infectious diseases, such as chytridiomycosis, which is contributing toward mass mortalities of amphibian species globally. The chytrid fungus (Batrachochytrium den-drobatidis) affects postmetamorphic amphibians (newly metamorphosed individuals are at the highest risk of lethal chytrid fungus infection) causing disruptions to important bodily functions, for example, osmoregula-tion and respiration (Bozinovic et al. 2011). Amphibians can potentially be at higher risk of infection following a weakened immune response as well as increased susceptibility to the pathogen due to chronic stress (Carey et al. 1999; Rollins-Smith 2001; Beebee and Griffiths 2005; Narayan and Hero 2014; Bovo et al. 2016).
Details
- Title
- Chapter 8: Assessing the physiological sensitivity of amphibians to extreme environmental change using the stress endocrine responses
- Creators
- Edward J. Narayan - Charles Sturt University
- Contributors
- Denis Vieira de Andrade (Editor of compilation) - University Estadual Paulista (Brazil, SP)Catherine R. Bevier (Editor of compilation) - Colby CollegeJosé Eduardo de Carvalho (Editor of compilation) - Federal University of São Paulo (Brazil, SP)
- Publication Details
- Amphibian and Reptile Adaptations to the Environment: Interplay Between Physiology and Behavior, pp.189-208
- Publisher
- CRC Press; Boca Raton, FL
- Edition
- 1
- Number of pages
- 20
- Identifiers
- 991013269206602368
- Copyright
- © 2016 by Taylor & Francis Group, LLC
- Academic Unit
- Faculty of Science and Engineering
- Language
- English
- Resource Type
- Book chapter