Effects of Chlorpyrifos and Endosulfan on Different Life Stages of the Freshwater Burrowing Crab Zilchiopsis collastinensis P.: Protective Role of Chorion

Abstract

The lethality (LC50) of endosulfan and chlorpyrifos is higher in adults (1990 and 156.78 lg/L respectively) than in embryos (95380 and 1242.54 lg/L respectively) of the crab Zilchiopsis collastinensis. The thickened embryonic coat of the freshwater species might isolate the embryo inside the egg, reducing the toxicity. Sublethal concentrations of chlorpyrifos and endosulfan caused an increase in hatching time and a decrease in effective hatching (p<.05), and only the control crabs survived until the first molt cycle. The effects of long-term exposure should be evaluated in the offspring in addition to the acute toxicity.