Cellular stress response, induction of micronuclei and DNA strand breaks in two common fish species of Rivers and Reservoirs in Ilorin, North Central, Nigeria.

Abstract Most rivers and reservoirs in the world are prone to pollution because of indiscriminate disposal of domestic, agricultural and industrial wastes into the water bodies. In this study, we investigated the ecotoxicological potential this could pose in fish species collected from major reservoirs and rivers in Ilorin, north central, Nigeria. Water samples were collected and the physicochemical parameters were examined from five different sites; Unilorin reservoir, Asa reservoir, Apodu reservoir, Asa river (Unity) and Asa river (Harmony). We determined serum biochemical (AST, ALT, ALP, serum ALB), histopathological (gill, lungs), serum antioxidant enzyme responses (SOD, CAT, GPx, GR, GST) which serves as a biomarker for evaluating oxidative stress while micronucleus and comet assays were used to detect level of DNA damage in Tilapia zillii and Clarias gariepinus. The physicochemical parameters and heavy metal analysed (Pb, Mn, Cu, Ni, N, P, Fe, Cl, and Ca) in the five different water bodies were below the permissible limits of WHO and USEPA except the DO, which was very low in the two rivers, indicating hypoxia. Our results showed significant increase in biochemical and hematological profiles, histopathological lesions in the gill and lungs, inductions of MN, NA and DNA single strand break in Tilapia zillii and Clarias gariepinus collected from Asa rivers compared to the Unilorin, Apodun and Asa reservoirs. This may be attributed to indiscriminate discharge of effluents from nearby industries, agricultural and domestic wastes into the rivers.