GROVE, L.E.*; BELDEN, L.K.; RUBBO, M.J.; KIESECKER, J.M.; Pennsylvania State University; Virginia Polytechnic Institute and State University; Pennsylvania State University; Pennsylvania State University: Effects of atrazine exposure on a Physid snail species and its trematode parasites

In recent years, the effect of the commonly used herbicide, atrazine, on amphibians has been examined extensively. Both deformities and mortality have been documented in amphibian larvae exposed to atrazine. In addition, parallels have been suggested between the presence of atrazine and an increased susceptibility to trematode parasitism in amphibian larvae. However, the effect of atrazine upon the other organisms in this freshwater disease system has not been studied in depth. During summer 2003, we completed several experiments to examine the effect of atrazine upon a first intermediate host in the trematode cycle, a freshwater snail (family: Physidae), as well as the free-swimming cercarial stage of the trematode (family: Teleorchidae), which emerges from the snails and infects the tadpoles. We completed a series of dose-response experiments independently examining the response of the snails and the free-swimming cercariae to 0, 30, 100, 250 or 500 ppb of atrazine. We discovered that the presence of atrazine had a limited effect on snail mortality. Similar results were found for the cercariae. These results, while preliminary, suggest that snails and trematode cercariae may be less impacted by exposure to atrazine than the potential tadpole hosts.