Impacts of cattle on amphibian larvae and the aquatic environment

Agricultural practices such as cattle farming may have direct or indirect negative effects on larval amphibians by decreasing water quality through deposition of nitrogenous waste, causing eutrophication, and grazing shoreline vegetation that contributes to detrital cover and food. We sampled amphibian larvae on the Cumberland Plateau, Tennessee, U.S.A., twice per week, water quality twice per month and algal and detrital biomass once per month at seven wetlands (three cattle-access and four non-access) from March to August 2005 and 2006. In general, species richness and diversity of amphibian larvae were greater in wetlands without cattle. Mean relative abundance of green frog (Rana clamitans) and American bullfrog (Rana catesbeiana) tadpoles was greater in non-access wetlands. Body size of some ranid larvae was larger in cattle-access wetlands but this trend did not exist for juveniles or adults. Dissolved oxygen was lower, while specific conductivity and turbidity were higher in cattle-access wetlands. Mean biomass of detritus was lower in cattle-access wetlands compared to non-access wetlands; no differences were detected in algal biomass. Given the negative impacts of cattle on water quality, detrital biomass, larval amphibian species richness and relative abundance of some amphibian species, we recommend that farmers consider excluding these livestock from aquatic environments.