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MA2 Amphibian Research and Monitoring
(020) The interactive effects of a pathogenic fungus (Saprolegnia sp.), a pesticide, and UV-radiation on amphibian larvae.
Bridges, C1, Boone, M1, Hopkins, W2, Little, E1, 1 US Geological Survey, Columbia Environmental Research Center, Columbia, MO, USA2 University of Georgia, Savannah River Ecology Laboratory, Aiken, SC, USA
ABSTRACT- It has long been suspected that environmental stressors can increase susceptibility to disease. We designed two experiments to examine the effects of environmental stressors on amphibians in the presence of a naturally-occurring pathogen. In the laboratory, we exposed spotted salamander larvae (Ambystoma maculatum) to the pesticide carbaryl, UV-B radiation, and the pathogenic fungus Saprolegnia and recorded time to mortality. In field mesocosms, we exposed southern leopard frog (Rana sphenocephala) tadpoles and spotted salamander larvae to carbaryl and Saprolegnia and recorded survival, size at metamorphosis, length of the larval period and, for metamorphosed tadpoles, percent lipid content. In the laboratory, larvae exposed to all three stressors died more quickly than larvae in other treatments. In the mesocosms, both carbaryl and Saprolegnia, (but not the interaction of these factors) reduced the survival of both amphibian species. Tadpoles exposed to both stressors had the lowest survival. Carbaryl, as well as the interaction between carbaryl and Saprolegnia, promoted greater mass at metamorphosis for tadpoles. This study illustrates the importance of examining multiple factors (both natural and anthropogenic) simultaneously when attempting to determine causes for amphibian declines.
Key words: carbaryl, amphibian, disease, UV radiation
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