Amphibian populations have been declining globally for several decades, and habitat modification and agricultural intensification appear to be partly responsible of these declines. The integrity of many aquatic environments is threatened by pesticide runoffs from agricultural lands. Amphibians are thus exposed to these compounds throughout their larval development. In North America, several herbicides, including metolachlor, are frequently applied to limit the growth of competing plant species and are found in high concentrations in aquatic environments. The addition of such contaminants adds to the other environmental stressors already at play in aquatic ecosystems. Pool drying, for example, is a prevalent environmental stress in ephemeral aquatic ecosystems and has a strong impact on the fitness of many amphibian species. Here we use a replicated mesocosm experimental design with different levels of pool drying and metolachlor concentrations (0; 0.8; 8; 80 ug/L) to assess their respective and combined effects on Wood Frog (Lithobates Sylvaticus) larvae throughout metamorphosis.
Results/Conclusions
Preliminary results suggest that pool drying decreases tadpole growth as well as length and mass at metamorphosis. Metolachlor, at environmentally relevant concentrations, did not appear to influence larval growth or mass at metamorphosis. Further analyses of our database will also focus on survival and development rates of the tadpoles exposed to those stressors. These preliminary results suggest that pool drying may exert mounting pressures on larval stages development. This project will provide important knowledge on the extent of interactions between environmental stressors, which is particularly relevant as global climate change and exposure to pesticides are important threats to amphibian populations.
