Genotoxic responses of Oreochromis niloticus to oil-contaminated water

Abstract

Moragoda Ela is an open canal connected with three cross drains that serve critical functions in the Galle Municipal area drainage system. However, the canal is under severe pollution stress due to numerous illegal discharge points of wastewater from commercial establishments adjoining the canal and contaminating water with polycyclic aromatic hydrocarbons (PAHs). The study aims to assess the genotoxic effects induced by these xenobiotic compounds with aquatic genetic biomarkers. Genotoxic alterations induced by these pollutants were investigated based on the micronucleus assay and erythrocytes nuclear abnormality assays in Tilapia fish (Oreochromis niloticus) exposed to this water for 10 and 28 days, respectively. A standard control experiment setup containing dechlorinated ground well water was set up to monitor deviation. Fish exposed to the water had significantly higher (p<0.05) nuclear abnormalities compared to the control fish exposed for the specified period. After exposure of the fish to the Moragoda Ela water for 10 and 28 days, a significant (p<0.05) increase in the genotoxic capacity of the water was evidenced. The study further revealed a time-dependent genotoxic effect on fish erythrocytes. Limited availability of affordable techniques to determine the different PAHs in Morgoda Ela water was a constraint during the study to obtain a comprehensive conclusion.