Exposure of fish fauna and other animals to organic, chemical and biological pollutants in Lake Nokoué in southern Benin: Literature review

Abstract

Lake Nokoué (South of Benin) is the most productive continental fisheries in West Africa with very strong biodiversity, but is gradually losing its resources because of pollution. In this study, we assessed the level of exposure of the fauna of this biotope. This lake has strong organic pollution with a hyper-eutrophic state. Analyzes of bacteriological germs indicate a strong fecal pollution capable of influencing the immune system of exposed organisms. The lake receives toxic metals (lead, cadmium, mercury, etc.), pesticides (endosulfan, DDT, etc), polycyclic aromatic hydrocarbons (naphthenes, fluorens, etc). Certain chemical pollutants such as industrial detergents, polychlorobyphenyls, dioxins and derivative products are also suspected in this lake, but no study has yet been initiated to show their presence. All these chemical pollutants are lipophilic and persistent, reprotoxic, hepatotoxic and inhibit the growth of aquatic fauna. Most are estrogenic endocrine disruptors which exert a threat to species survival. The bioaccumulation of pollutants in fishery products of the lake at concentrations sometimes exceeding international standards, exposes consumers and poses a serious public health problem.

Keywords: Pollution, lake Nokoué, aquatic fauna, species extinction