Biological monitoring of organochlorides using the limnic bivalves Anodontites trapesialis (Lam., 1819).

The mussel Anodontites trapesialis (Lam, 1819) was used as an indicator of organochloride pollutants in the Canoas River, located in the municipality of Mococa (21 degrees 25'08''S and 47 degrees W), State of São Paulo, Brazil. Biological monitoring was performed for one year at the site of an orange grove on the left bank of the river. Forty-five animals were placed in aluminum enclosures on the river bottom at this site and 4 animals were sacrificed for pesticide analysis at 3-month intervals, each corresponding to one season of the year. Pesticides were extracted by the method of Bedford et al., (1968), modified, and the analyses were performed by gas phase chromatography equipped with an electron capture detector. The animals were found to have been exposed to DDT, Lindane and Heptachlor. Variation in Aldrin and Dieldrin levels was not significant enough to permit inferences. Endrin was not detected in any of the analyses.