Conservative estimates of worldwide declining amphibians and chytridiomycosis threat

18 August 2005

Letter to the editor that was unpublished critizicing the paper:

Stuart, S. N., J. S. Chanson, N. A. Cox, B. E. Young, A. S. L. Rodriguez, D. L. Fischman, and R. W. Waller. 2004. Status and trends of amphibian declines and extinctions worldwide. Science 306:1783-1786. DOI: 10.1126/science.1103538

 

In this letter I discuss the Global Amphibian Assessment results (Stuart et al. 2004) in terms that the authors may have overestimated the threat to amphibians in several instances. I provide a conservative estimate of the number of amphibians that can be considered threatened.

The Global Amphibian Assessment tried to determine the current status of amphibians worldwide and concluded that they are more threatened than mammals and birds. However, as I discuss in the manuscript, they used a liberal definition of decline, when it has been discussed in the literature that the only way to determine the status of a population is by long term population studies. Only 420 species reported population studies, which suggest a possible overestimation of the number of species declining.

In addition, I discuss the assignment of a threat of chytridiomycosis to many species without any evidence. Some studies suggest that some amphibians may be resistant and have defenses to the disease, which indicates that each species must be assessed individually to determine if chytridiomycosis is a threat or not.