Impact of Ogun River pollution on antioxidants and proximate composition of African catfish (Clarias gariepinus)

Abstract

Most rivers in Nigeria are polluted without conscious efforts to abate ensuant consequences. Thus, Clarias gariepinus, an aquatic commercial food from Ogun River, Nigeria, was studied to investigate the impact of pollution on antioxidants and proximate composition. During the rainy season, 50 C. gariepinus (average weight 426.53 ± 24.40g and length 37.73 ± 0.95cm) were site sampled, 10 from each of Ago-Odo, Ago-Ika, Oke-Sokori, and Quarry along Ogun River course. Ajegunle-Adao cultured pond, served as control. The parameters assayed for included: some heavy metals and physico-chemical properties of sampled water, antioxidants and proximate composition of the fish samples. Physicochemical parameters of river studied showed that temperature of all sites ranged from 26 to 29°C, pH: 6.9 to 7.8, dissolved oxygen: 9.5 to 21.6, biochemical oxygen demand: 3.60 to 14.10, and chemical oxygen demand: 60 to 650. Lead (Pb) concentration ranged from 4.0 to 17.0 μg/L and cadmium (Cd): 0.0 to 6.0 μg/L. Blood Pb, Cd, activities of: superoxide dismutase, catalase, glutathione-S-transferase, plasma xanthine oxidase, and lipid peroxidation level of fish samples from Ago-Ika were most significantly (p < 0.05) high, with significant (p < 0.05) lowest reduced glutathione concentration amongst the samples from polluted sites when compared to control fish. Proximate analysis showed that the fish samples from Ogun River had significantly (p < 0.05) lower protein, fat contents, and higher nitrogen-free extract while Ago-Ika, Oke-Sokori and Quarry sites had significantly (p < 0.05) lower moisture, ash and fibre contents when compared with control. It can be concluded that the impact of pollution induced oxidative stress and significantly diminished the nutritional value of C. gariepinus from Ogun River.