Multiple biomarker responses of Nile tilapia (Oreochromis niloticus) exposed to textile industry effluents reaching Bolgoda North Lake, Sri Lanka

Abstract

Textile industry effluents contain a complex mixture of chemicals which may have potential threats to biota. The present study was carried out to assess the potential impacts of selected textile industry effluents entering Bolgoda North Lake, Sri Lanka using multiple biomarkers responses of Nile tilapia viz. brain acetylcholinesterase (AChE), hepatic ethoxyresorufin O-deethylase (EROD) and erythrocytic micronuclei/nuclear alterations. The biomarker responses were determined in the fish upon exposure to the undiluted and diluted effluents along with the respective controls. Brain AChE activities of the fish exposed to the textile industry effluents were depressed (up to 40%) and frequencies of erythrocytic micronuclei and nuclear alterations were increased (up to 9 folds) significantly indicating the availability of neurotoxic and genotoxic substances in the effluents. Strong induction of hepatic EROD activities (up to 23 folds) in the exposed fish revealed the availability of CYP1A inducing pollutants which may have contributed to enhance the genotoxic potential of the effluents. The results revealed the sensitivity of these biomarkers of Nile tilapia to assess the biological effects of textile industry effluents. The depression of AChE activities and induction of EROD levels along with enhanced micronuclei and nuclear alterations in the fish exposed to the selected effluents can be considered as early warning signs for possible impacts pose by the textile industry effluents on fish populations inhabiting the effluent receiving water bodies.