Almost one-third of Indian Amphibian Species threatened by Climate Change: Study

By Aayushi Sharma

A new study published in the Nature Journal details how amphibian species are declining globally due to climate change, and these species remain the most vulnerable group of vertebrates. 

The 2004 baseline study reported habitat loss, degradation, and over-exploitation as the primary threats, leading to the deterioration of over half of the species that deteriorated in status between 1980–2004, while 48% were classified as enigmatic-decline species.

Key findings for India

An international team of researchers, including those from the Council of Scientific & Industrial Research-Centre for Cellular and Molecular Biology (CSIR-CCMB), Hyderabad, and other Indian institutes, found that 136 of the 426 species evaluated in the study were threatened in India.

Kerala has 178 species, of which 84 are threatened, followed by Tamil Nadu with 128 species, of which 54 are threatened, and Karnataka in third place with 100 species, of which 30 are threatened among the states with high amphibian diversity.

The study found that the Western Ghats of India had the highest concentrations of threatened species. The tropical Andes, Mesoamerica, the Caribbean islands, the mountains and forests of western Cameroon and eastern Nigeria, Madagascar, and Sri Lanka were among the other regions.

Key findings on amphibian species and climate change in the second global assessment

The second Global Amphibian Assessment, finished in June 2022, reevaluates the species from the first assessment while evaluating a larger number of species examined by the researchers for this study.

Amphibians remain more threatened than birds (13%), mammals (27%), or reptiles (21%), with 41% of assessed species in the Critically Endangered, Endangered, or Vulnerable Red List categories. Agriculture is the most frequent cause of habitat loss and degradation that endangers frogs. With 60% of their species falling under one of the three threatened Red List categories, salamanders are the most vulnerable of the three orders of amphibians.

Nearly half of all amphibians worldwide are found in the Neotropics, the most threatened region, with 48% of its species classified as endangered.

Between 1980 and 2004, chytridiomycosis was the leading cause of increases in the extinction risk for amphibians; however, between 2004 and 2022, the effects of climate change took precedence.

How does climate change affect the amphibian population?

Amphibian species with limited tolerance to specific temperature and moisture regimes may be particularly vulnerable. Particularly vulnerable are amphibians that depend on particular habitat types, such as those found in ephemeral ponds and streams that may dry up before the annual reproductive cycle is finished. Amphibians are particularly vulnerable to the anticipated effects of climate change due to various factors.

Firstly, Amphibians have been recognized as declining globally for more than 20 years. Approximately one-third of amphibian species are in danger of going extinct, making them one of the taxonomic groups most at risk of extinction. The main threat factors are the loss of habitat, illness, invasive species, overexploitation, and chemical pollution.

Secondly, Every plant and animal species has unique phenological patterns correlated with regional climates. Climate change could bring phenological changes, particularly for species that breed early or late in the season. A change to earlier breeding could expose amphibians to more variable weather. Animals may freeze, for instance, if there is a warm stretch in late winter and a cold snap shortly after breeding. Deep freezes can potentially affect animals that emerge in the spring or hibernate over the winter. Additionally, the size of annual recruits at metamorphosis may be related to their survival, which may depend on the timing of breeding.

What do experts say?

Dr Hari Krishnan S, Project Manager, Amphibian recovery project, Munnar, told CFC India, “Amphibians and reptiles (herpetofauna) are ectothermic animals, which means that their biology is strongly linked with temperature and precipitation. The distribution and diversity of herpetofauna closely track the changes in temperature across the globe. Many of these, especially tropical species endemic to small areas such as mountain peaks, have rather narrow windows of temperature and precipitation ranges that are necessary for their survival.”

Climate change-induced temperature and precipitation variation may force these species to respond in several ways. One is to make behavioral changes that may help them adapt. However, it is difficult to predict which species may be capable of doing this. A second possible response is to evolve changes in their biology to suit the changing environment better. This, is a long shot, as it requires character evolution to happen fast enough to match the speed of current climate change. The third possible response is that species may have to move in search of suitable climate refugia. This is a somewhat well-documented phenomenon. However, this will still be a challenge for herpetofauna in India due to lack of habitat availability and connectivity. 

“Not being able to respond to changes in temperature and precipitation in at least one of these three broad pathways is very likely to push species towards extinction. For example, the Resplendent Bush Frog (Raorchestes resplendens) occurs only in the high elevation grasslands (above 2000 m asl) around Eravikulam National Park in the Munnar region. As temperatures rise, there are no higher elevation habitats towards which they can move. They are essentially stuck in this “Sky Island” habitat.”, added Dr Harikrishnan S. 

References:

• https://www.nature.com/articles/s41586-023-06578-4
• https://www.iucn-amphibians.org/red-listing/global-amphibian-assessment-2/
• https://www.ptinews.com//news/health-and-lifestyle/climate-change-endangering-amphibian-species-around-the-world-136-of-426-in-india-threatened-study/664411.html
• https://www.business-standard.com/india-news/climate-change-threatens-amphibians-136-of-426-species-in-india-at-risk-123100501018_1.html
• https://theprint.in/india/climate-change-endangering-amphibian-species-around-the-world-136-of-426-in-india-threatened-study/1791645/
• https://www.nationalheraldindia.com/environment/climate-change-threatens-amphibians-worldwide-136-indian-species-at-risk-study
• https://www.science.org/doi/10.1126/science.1103538
• http://www.fs.usda.gov/ccrc/topics/amphibians-and-climate-change
• Image source: https://www.freepik.com/free-photo/whitelipped-tree-frog-litoria-infrafrenata-green-leaves-whitelipped-tree-frog-litoria-infrafrenata-closeup_26795312.htm#query=Frog&position=8&from_view=search&track=sph
• https://www.freepik.com/free-ai-image/swimming-slow-hawksbill-turtle-maui-reef-generated-by-ai_40998161.htm