Acute Toxicity of Parathion and 2,4-D to Larval and Juvenile Stages of Chasmagnathius granulata (Decapoda, Brachyura)

Chasmagnathus granulata is a species of estuarine crab distributed along the littoral zone of Samborombon Bay, Argentina. All stages of the life cycle of this species form part of the aquatic trophic web. Alevins of several fish species of commercial and sport fishing value prey on the larvae and juveniles. Parathion and 2,4-D pesticides are extensively used in Argentina and have reached the bay through several rivers and channels that flow into it. A study was done to establish the concentrations of parathion and 2,4-D that would be dangerous to the survival of the most sensitive stages of the life cycle of this estuarine crab. Parathion showed a significantly higher toxicity than 2,4-D. Zoeae were the most sensitive to both pesticides.