WIDDER, P.D.*; BIDWELL, J.R.; Virginia Polytechnic Institute and State University; Oklahoma State University: Tadpole Swim Speed and Organophosphate Pesticide Exposure

While methods exist to verify exposure of amphibians in natural populations to agricultural chemicals through the use of physiological biomarkers, the ecological relevance of changes in these parameters is unknown in amphibians. We examined the relationship between changes in tadpole cholinesterase (ChE; a common enzymatic biomarker of exposure to OP pesticides) and measures of growth and swim speed in four native North American species of anurans (Hyla chrysoscelis, Rana sphenocephala, Acris crepitans, and Gastrophryne olivacea). We used four environmentally realistic levels (1, 10, 100 and 200 �g/l) of a commonly used organophosphate pesticide (OP), chlorpyrifos, and examined tadpole response at the conclusion of four days of exposure. We further examined if the presence or absence of pond sediment influenced tadpole responses, and in two species we examined how longer exposure (twelve days) influenced response. We found species-specific differences in response to the pesticide, with H. chrysoscelis and G. olivacea being more sensitive than the other two species. Furthermore, we found the presence of sediment to influence response, although effects were not consistent among species. Given these differences, we recommend exercising caution when making generalizations across different anuran taxa regarding pesticide exposure response.