$2.1 Million Grant Awarded to Yale and Penn State Researchers to Study Deformities in Frogs

A $2.1 million grant has been awarded to Yale and Penn State researchers to investigate what is causing deformities in amphibians, such as frogs found with extra hind limbs.

The five-year study will be concentrated in the Northeast and will attempt to determine where the deformed amphibians are most common and what might be causing the problem. Two theories lay the blame on parasites or pollutants.

Amphibian deformities have been reported in more than 40 states and in several countries. Reports of amphibian deformities first captured national attention five years ago when school children in Minnesota discovered a pond containing large numbers of frogs with extra hind limbs and with deformed limbs.

The researchers who were awarded the grant from the National Institutes of Health are David Skelly, assistant professor of ecology at the Yale School of Forestry and Environmental Studies, and Joseph Kiesecker and Katriona Shea, both of the Department of Biology at Pennsylvania State University.

Skelly said there is a great deal of interest in what is causing deformities in frogs and other amphibians because it might be a symptom of a larger problem.

“Amphibians have been nominated as ‘canaries in the coalmine,’” he said. “Some people think that whatever is making amphibians sick also may be a risk to human health or to the broader health of the environment.”

Skelly and his collaborators are particularly interested in whether the deformities are caused by trematodes, a group of parasites also responsible for often fatal human diseases, among them schistosomiasis, which is often found in tropical regions.

Although there is no evidence of a risk to humans from the particular parasites which infect amphibians, frogs may provide a good model for studying the means to control human disease.

The study will be conducted in four states - Pennsylvania and Connecticut, which tend to have a lower than average incidence of amphibian deformities, and New York and Vermont, which have a higher than average incidence of deformities in amphibians.

Skelly said trematodes depend on snails as hosts before they infect amphibians. Because of changes in their environment, snails may be proliferating.

“People may be doing things to wetlands that inadvertently turn wetlands into snail farms - such as making the wetlands deeper, introducing nutrients, or cutting trees to let in more light - all of which make snails happy,” he said.

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