A multibiomarker study evaluated WWTP effluent effects on clams in water columns.WWTP effluents were toxic to clams in adjacent marine and fresh water environments.Defence mechanisms increased in marine clams nearest to WWTP discharges.96% of clams exposed directly to WWTP effluent in Guadalete River died before day 7.We showed that the multibiomarker approach provides important ecotoxicological data.
