Comparative sensitivities of larval stages of the cane toad, Rhinella marina, and the striped marsh frog, Limnodynastes peronii, to atrazine

Variations in larval sensitivities to atrazine were determined in the Australian native striped marsh frog, Limnodynastes peronii, and the introduced cane toad, Rhinella marina. The static acute test design involved six nominal concentrations of atrazine, including control, solvent control, 3, 6, 12, and 24mgL^-1. Gosner stages 22-23 as hatchlings, stages 25-26, 28-29, and 32-33 as premetamorphic, 36-37 as prometamorphic and 40-41 as metamorphic climax stages of cane toads and the first four sets of Gosner stages of striped marsh frogs were exposed to atrazine treatments for 96h. Results showed that late larval stages were more sensitive than early stages and different premetamorphic stages showed variations in sensitivities in both test species. The striped marsh frog showed a stronger concentration-and stage-dependent response and greater sensitivity to atrazine than the cane toad. In both experimental species, Gosner stages 28-29 showed better concentration-dependent increase in sensitivities to atrazine compared with other larval stages. It can be concluded that inter-and intra-species variations in sensitivities to atrazine may occur in Australian anurans and native species may show greater sensitivity to acute concentrations of atrazine than the introduced cane toad.