Analysis of Pesticide Exposure on Salamander Populations in Great Smoky Mountains National Park

Linquist, Erik

Pesticides are one of several environmental stressors likely to be involved in global amphibian declines. Numerous studies have demonstrated that very low levels of pesticides may have significant negative biological effects on amphibians. Evidence of aerial transport of pesticides over considerable distances has raised concern for pristine wilderness and preserved areas, including national parks. We investigated geographic patterns of pesticide residues in Black-belly Salamanders (Desmognathus quadramaculatus; Plethodontidae) in the park. In 2001, we conducted a pilot study, collecting tissue samples from two sites (north and south of the eastern continental divide) near the western boundary of GRSM. At the northern site, the samples revealed detectable levels of DDT metabolites and the organophosphate chlorpyrifos. In 2003, we conducted a large scale geographic analysis of pesticide residues in Black-belly Salamanders by collecting tissue samples from the same two sites and an additional six sites, forming two east-west transects on either side of the continental divide. The results revealed measurable levels of numerous pesticide residues, including DDT and its metabolites, as well as chlordane, heptachlor, endosulfan, and atrazine. The geographic pattern was quite heterogeneous; however, samples from the two most western sites did exhibit the greatest variety of pesticide residues. Our study indicates that amphibians within the GRSM are being exposed to both historical and current use pesticides. These environmental stressors may therefore pose significant risks to some amphibian species within the park.