October 31, 2008

More About Climate Change and Amphibian Declines

The role of climate change as a driver of amphibian declines is a controversial topic. As I described in my 3/27/2008 post, an article by Pounds et al. in Nature suggested that climate warming in South America was responsible for the emergence of the amphibian chytrid fungus (Batrachochytrium dendrobatidis) and subsequent catastrophic amphibian declines on that continent. These results have been challenged on several grounds, and in my view remain conjectural at best.

An article just published in the Proceedings of the National Academy of Sciences provides much clearer evidence that recent climatic anomalies have resulted in declines of amphibian populations. The authors report that six decades of climate data for Yellowstone National Park shows a trend of increasing temperatures and decreasing precipitation. These changes in temperature and precipitation have caused many of the ponds in the study area to dry up. This, in turn, has resulted in marked decreases in the number of sites occupied by three species of amphibians: blotched tiger salamander (Ambystoma tigrinum melanostictum), boreal chorus frog (Pseudacris triseriata maculata), and Colombia spotted frog (Rana luteiventris). These results are certainly of concern, but it remains to be seen whether these patterns hold up over the longer term.

Direct effects of climate change on amphibians due to consequent changes in habitat are likely to increase in severity in coming decades. Even the mountain yellow-legged frog, a species that requires permanent water bodies for successful breeding and overwintering, will likely be affected as what were once permanent lakes, ponds, and streams become ephemeral. Such changes could spell extinction for many populations of this already imperiled species.

Back to The Mountain Yellow-legged Frog Site.

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