Biomarker responses as indicator of contaminant effects in <i>Sarotherodon melanotheron</i> (Pisces: Cichlidae)

Abstract

This study investigated lipid peroxidation and enzymes activities in Black jaw tilapia Sarotherodon melanotheron from Agboyi Creek with aim of assessing contamination status of sampling site in Agboyi creek in comparison to a reference site in Langbasa, Palava Island. Water quality parameters recorded no significant differences (p<0.05) between sites and were within limits recommended by Federal Ministry of Environment (FMEnv) throughout study period. The mean levels of heavy metals (Fe, Cu, Mn, Zn, Pb, and Cd) concentrations were also within maximum concentration recommended except for Fe. The levels of Thiobarbituric acid-reactive substances (TBARS) (2541.67 nmol /mg Protein) and Superoxide dismutase (SOD) activity (54.66 Min/mg/pro) increased significantly (p<0.05) in liver of S. melanotheron from Agboyi creek in relation to reference site. Catalase (CAT) activities on the other hand were significantly decreased in liver of S. melanotheron from Agboyi creek in relation to reference location. The decrease of catalase (CAT) activity in the liver of S. melanotheron together with increase of SOD activity, could explain the increased lipid peroxidation (LPO) levels in the liver. The antioxidant induction in liver of examined fish samples suggests exposure to contaminants with potential for severe damage to tissues of biota and calls for continuous monitoring and effective policy to protect this ecosystem.

Keywords: Antioxidant enzymes, Lipid peroxidation, Liver, Agboyi creek