Responses of B-esterase enzymes in oysters (Crassostrea gigas) transplanted to pesticide contaminated bays form the Ebro Delta (NE, Spain)

► B-esterase activity responses in oysters cultured in Ebro Delta were measured. ► Cholinesterase activities in oyster gills were unaffected across sites and periods. ► Carboxylesterase activities in oyster gills varied across periods and sites. ► Carboxylesterase were correlated with residue levels of anti-cholinergic pesticides.