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

Abstract

Lake Nokoué-lagoon of Porto-Novo complex, as a surface water body, is exposed to heavy pollution whose intensity vary across seasons. The present study aimed to assess the bioaccumulation of lead and cadmium levels by. Sarotherodon melanotheron fish, one of the most populated fished in this complex. To this end, fish, water and sediment were sampled during high-water and low-water. Lead and cadmium were quantified from different samples using a flame atomic absorption spectrometry. Health risk associated to the fish consumption was estimated.  In the water samples, lead concentration was higher during high water (0.106 ± 0.116 mg/l) compared to low water 0,069 ± 0,041mg/l), p< 0.05; cadmium concentration was higher during low water (0,010 ± 0,001mg/l) compared to high water (0,017 ± 0,012 mg/l). 

In the sediment samples, lead concentration was higher during high water (13.94 ± 20.79 mg/kg) compared to low water 12,45 ± 3,47 mg/kg), p< 0.05; cadmium concentration was higher during low water (0,2 ± 0,06 mg/kg) compared to high water (0,17 ± 0,12 mg/kg).   On the other hand, high concentrations of lead and cadmium in fish were found during low water, respectively 27.66 mg/kg and 0.22 mg/kg in the muscle, 10.36 mg/kg and 0.25 mg/kg in the gills, and 5.27 mg/kg and 0.17 mg/kg in the female gonads. Cadmium concentration in fish is significantly correlated with dissolved oxygen and water pH. 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.