A tale of two pesticides: how common insecticides affect aquatic communities

摘要: Summary 1. Recent ecotoxicology studies show that pesticide exposure can alter community composition, structure and function. Generally, responses to pesticides are driven by trait- density-mediated indirect effects resulting from sublethal lethal of on vulnerable taxa. These depend upon the concentration frequency exposure. 2. While more research is needed understand community-level exposure, testing multitudes registered chemicals ecologically relevant communities overwhelming. Recent reviews suggest contaminants with similar modes action should produce comparable because they have direct and, as a result, effects; this hypothesis remains largely untested. 3. We subjected pond [containing zooplankton, phytoplankton, periphyton leopard frog tadpoles (Rana pipiens)] several applications (single medium or high concentrations weekly lower concentration) two acetylcholine esterase inhibiting insecticides, malathion carbaryl toxicity for aquatic organisms. 4. We found both insecticides cause trophic cascades affect zooplankton phytoplankton abundances; however, their amphibians diverged, especially when exposed higher insecticides. Malathion caused cascade beginning decline in cladocerans followed increases phytoplankton. At concentration, also subsequent decrease periphyton. Carbaryl highest application, weak application no smallest application. directly reduced tadpole survival at all concentrations. Survivors treatments were larger metamorphosis while survivors lowest smaller developed slowly. In contrast, was not toxic tadpoles, but indirectly slow growth development prevented some metamorphosing before mesocosms dried low applications. 5. These results these common pesticides, which share same mode action, algae, differences strength timing reduce generality levels. Overall, general predictive models contaminant could be improved incorporating relative exposure.