Study of heavy metal contamination of Sarotherodon melanotheron and Crassostrea gasar in Casamance river (Senegal)

Abstract

The Casamance estuary has experienced a lack in research activities over the past decades, leading to a knowledge gap, particularly regarding resource quality. This study aimed to establish a baseline for heavy metals (cadmium, lead and mercury) contamination in Casamance estuary before oil exploitation begins in Senegal. Samples of tilapia (Sarotherodon melanotheron) and oysters (Crassostrea gasar) were seasonally collected between 2022 and 2023 in Niamone-Kalounayes et Kasa Balantacounda marine protected areas and in Carabane near the embouchure. Heavy metal concentrations were determined using atomic absorption spectrometry (AAS). The results showed that only Cd and Pb were detected in the targeted species, with concentrations varying by season. The mean cadmium concentration in S. melanotheron muscle (0.07 mg.kg^-1) exceeded the European Union standard (0.05 mg.kg^-1). However, Cd and Pb concentrations in oysters remained below the European standards of 1 mg.kg^-1 and 1.5 mg.kg^-1, respectively. A human health risk assessment based on the Target Hazard Quotient (THQ) indicated that the consumption of S. melanotheron and C. gasar does not pose a significant risk to public health