Effects of atrazine on embryos, larvae, and adults of anuran amphibians

We examined the effects of atrazine (0-20 mg/L) on embryos, larvae, and adu lt anuran amphibian species in the laboratory. Atrazine treatments did not affect hatchability of embryos or 96-h posthatch mortality of larvae of Ran a pipiens, Rana sylvatica, or Bufo americanus. Furthermore, atrazine had no effect on swimming speed (measured for R. pipiens only). However, there wa s a dose-dependent increase in deformed larvae of all three species with in creasing atrazine concentration. In adult R. pipiens, atrazine increased bu ccal and thoracic ventilation, indicating respiratory distress. However, be cause atrazine had no affect on hemoglobin, this respiratory distress was p robably not indicative of reduced oxygen-carrying capacity of the blood. Fr ogs exposed to the highest atrazine concentration stopped eating immediatel y after treatment began and did not eat during the 14-d experiment. However , no decreases in mass were measured even for frogs that were not eating, p robably because of compensatory fluid gain from edema. Atrazine concentrati ons found to be deleterious to amphibian embryos and adults are considerabl y higher than concentrations currently found in surface waters in North Ame rica. Therefore, direct toxicity of atrazine is probably not a significant factor in recent amphibian declines.