Associations of amphibians with environmental covariates and estimation of the prevalence of the pathogen Batrachochytrium dendrobatidis in north-central Iowa wetlands
Contaminants, habitat degradation, and the pathogen Batrachochytrium dendrobatidis (Bd) are among suspected culprits for worldwide amphibian declines, however; little field research has been done to examine these factors in the Midwestern US. In 2006 I conducted amphibian surveys at 29 wetlands in north-central Iowa, a region dominated by intensive row crop agriculture. I utilized three survey techniques to document amphibians and used the information-theoretic approach to choose models that best estimated relationships between successful reproduction and species richness, and the parameters: pesticides, nutrients, wetland density, proportion cropland in the landscape, and fish. I collected swab samples from Rana pipiens and tested them for the presence of Bd. Alachlor, phosphate, and fish were negatively associated with successful reproduction of Rana pipiens and alachlor and fish were negatively associated with reproductive success of Pseudacris triseriata. Fish were negatively associated with anuran species richness. I detected Bd on samples from 23% of sites.