Assessment of Lead and Cadmium Bioaccumulation by Tilapia, Sarotherodon melanotheron (Rüppell 1852), from the Lake Nokoué Lagoon of Porto-Novo Complex, Benin Republic

Lake Nokoué-lagoon of Porto-Novo complex, as a surface water body, is exposed to heavy pollution whose intensity varies across seasons. The present study aimed to assess the bioaccumulation of lead and cadmium levels by Sarotherodon melanotheron fish, one of the most populated fish in this complex. To this end, fish (muscle, gills, female gonads), water, and sediment were sampled during high-water and low-water. Lead and cadmium were quantified from different samples using flame atomic absorption spectrometry. The health risk associated with fish consumption was estimated. In the water samples, lead concentration was higher during high water (0.106 ± 0.116 mg.L-1), and cadmium was higher during low water (0,010 ± 0,001 mg.L-1). In the sediment samples, lead was higher during high water (13.94 ± 20.79 mg.kg-1), cadmium was higher during low water (0,2 ± 0,06 mg.kg-1). On the other hand, high concentrations of lead and cadmium in fish were found during low water, respectively 27.66 mg.kg-1 and 0.22 mg.kg-1 in the muscle. Cadmium accumulation in fish is influenced by dissolved oxygen and the pH of the water. Consumption of 400 g of Sarotherodon melanotheron fish from this complex per week constitutes a health risk for anyone weighing between 0 and 90 kg.