Modular Estuarine Mesocosm Validation: Ecotoxicological Assessment of Direct Effects with the Model Compound Endosuolfan

The feasibility of using a modular estuarine microcosm to test for direct pesticide effects on estuarine life was examined. The agricultural insecticide endosulfan was chosen as a model contaminant for assessing toxicity effects on the grass shrimp, mummichog, fiddler crab, and eastern oyster. The mesocosm experiment showed that the shrimp and mummichog exposed to endosulfan had significant mortality rates compared with those not exposed, but fiddler crabs and eastern oysters showed no effect. The mesocosm approach also proved useful for demonstrating endosulfan bioconcentration in oysters, at levels similar to those reported in previous field studies. The modular mesocosm approach appears useful for detecting direct effects of pesticide exposure and uptake in estuarine fauna.