Biomarkers of Oxidative Stress and Heavy Metal Levels as Indicators of Environmental Pollution in Some Selected Fishes in Lagos, Nigeria

摘要

Levels of zinc, lead and copper in the flesh of catfish: Clarias gariepinus, Chrysichthys nigrodigitatus and Tilapia: Oreochromis niloticus, Tilapia guinensis, were determined using Bulk Atomic Absorption Spectrophotometer. Clarias gariepinus and Oreochromis niloticus were collected from a Fish farm in Ayobo, Lagos Nigeria, which was considered as reference site. Tilapia guinensis and Chrysichthys nigrodigitatus were collected from the Lagos Lagoon. The activities of superoxide dismutase (SOD), glutathione (GSH) concentration and Malondialdehyde (MDA) formation were also determined. Heavy metals were accumulated in the flesh of the fish to varying extent. The trend of accumulation of the metals is as follows: Catfish-Cu>Pb>Zn: Tilapia-Cu>Pb>Zn. The concentration of heavy metal in the flesh of the fish from the Lagos Lagoon is higher than that from the reference site for all the metals analyzed. SOD concentration in the liver of the Tilapia guinensis increased by 12.3% when compared to Oreochromis niloticus, the SOD concentration in the gills of Oreochromis niloticus increased by 26.22% when compared to Tilapia guinensis. GSH levels increased in the liver and gills of Tilapia guinensis and Chrysichthys nigrodigitatus by 17.82% and 30.14% respectively and in the gills, GSH increased by 8.6% and 12.64% in Tilapia guinensis and Chrysichthys nigrodigitatus, respectively. MDA levels were increased in the liver of Tilapia guinensis by 15.22% and Chrysichthys nigrodigitatus by 12.6%. In the gills, MDA increased by 13.1% in Tilapia guinensis and 6.98% in Chrysichthys nigrodigitatus. The result demonstrates that alteration in the antioxidant enzymes and induction of lipid peroxidation reflects the presence of heavy metals which may cause oxidative stress in Tilapia guinensis and Chrysichthys nigrodigitatus from the Lagos Lagoon. The study therefore provides a rational use of biomarkers of oxidative stress in biomonitoring of aquatic pollution.