USD professor helps dispute amphibian environmental myth

VERMILLION, S.D. -- A team of researchers, led by Assistant Professor Jacob Kerby of The University of South Dakota, have determined that amphibians are not uniquely susceptible to pollution.

What does this news mean to the environment from an ecological standpoint? The research challenges a long-standing opinion that amphibians are not the venerable “canaries in a coal mine” of environmental corrosion as once thought. According to meta-analysis published recently in Ecology Letters, a peer-reviewed scientific journal known for publishing groundbreaking ecological research, amphibians – despite their permeable skin and aquatic environment – aren’t as vulnerable to habitat degradation due to pollution. After reviewing more than 28,000 toxicological tests, Kerby, an assistant professor in the USD Department of Biology, along with researchers from the Yale School of Forestry & Environmental Studies and Washington State University, challenge the opinion that amphibians are dependable predictors of environmental decline.

“What our results suggest is that all animals are susceptible to chemical stressors, and that amphibians are potentially good indicators,” noted Kerby, who has taught at The U since August 2008. “There isn’t any evidence that they’re a uniquely leading indicator. We tried to be wide-ranging in the types of chemicals and organisms we looked at.”

The team’s research paper, “An Examination of Amphibian Sensitivity to Environmental Contaminants: Are Amphibians Poor Canaries?”, featured in Ecology Letters, stated that the Environmental Protection Agency uses African Clawed Frogs as a surrogate for biological diversity when determining a species’ sensitivity to chemical exposures. The researchers utilized the EPA’s Aquatic Toxicity Information Retrieval database and examined 1,279 species such as segmented worms, fish, clams, insects and snails, which were exposed in water to various concentrations of chemical agents. The chemicals included inorganic chemicals, pesticides, heavy metals and phenols, a class of chemical compound.

A majority of the analysis indicated that frogs range from being moderately susceptible to being impervious to various chemicals. Despite the well-documented widespread decline of amphibian populations worldwide, this research begs the question of what is occurring in the more sensitive taxa. “While it might be easy to notice the disappearance of calling frogs from a stream,” he added, “it is a bit less obvious to notice missing mayfly larvae.”

In lieu of these findings, Kerby and his research team determined that scientists should evaluate the absence, presence or abundance of amphibians in wild populations as “signals” of potential exposure to different chemicals in the environment. With an understanding of several species and their reactions to change, their research determined, scientists could be able to use the responses as a means of narrowing potential causes of environmental degradation.

An Examination of Amphibian Sensitivity to Environmental Contaminants: Are Amphibians Poor Canaries?”appears in the most recent issue of Ecology Letters. An abstract of the paper is currently available for view at http://www3.interscience.wiley.com/journal/122658158/abstract.

A photograph of Kerby is available for download at www.usd.edu/urelations/images/Jacob_Kerby.jpg.