CHOLINESTERASE ACTIVITY IN Crassostrea SP. OF NAYARIT (NW MEXICO) COASTAL WATERS

Resumen

Cholinesterases (ChE) have been suggested as biomarkers of the presence of organophosphorus insecticides (OP). The activities of these enzymes were determined in abductor muscle, gills and labial palps of oysters collected during the rainy and the dry seasons at eight points of the coastal zone of Nayarit state (NW Mexico), aiming to determine if their variability is related to geographic and seasonal differences in the use of OP. At all stations, ChE mean activity was lower in the dry than in the rainy season, and the muscle had consistently lower values than gills and labial palps. Lower activities were found in Bahía de Banderas, in the southern part of the state, than in the northern stations. This may be explained by the year-round use of OP insecticides in the southern part of the state, whereas herbicides are the most common pesticides used in agricultural areas draining into the northern stations during the rainy season.