Are exploited mangrove molluscs exposed to Persistent Organic Pollutant contamination in Senegal, West Africa?

• Published in: Chemosphere (Oxford) Vol. 84; no. 3; pp. 318 - 327
• Main Authors: Bodin, N., N’Gom Ka, R., Le Loc’h, F., Raffray, J., Budzinski, H., Peluhet, L., Tito de Morais, L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-06-2011; Elsevier
• Subjects: Animal, plant and microbial ecology; Animals; Applied ecology; bioaccumulation; Biodiversity and Ecology; Biological and medical sciences; Bivalvia; Bivalvia - metabolism; DDT (pesticide); developing countries; Ecosystem; ecosystems; Ecotoxicology, biological effects of pollution; Environmental Monitoring; Environmental Sciences; estuaries; Estuary; ethers; Fisheries - statistics & numerical data; Fundamental and applied biological sciences. Psychology; Gastropoda; Gastropoda - metabolism; Halogenated Diphenyl Ethers - analysis; Halogenated Diphenyl Ethers - metabolism; heptachlor; Heptachlor - analysis; Heptachlor - metabolism; hexachlorobenzene; Hexachlorobenzene - analysis; Hexachlorobenzene - metabolism; Hydrocarbons, Chlorinated - analysis; Hydrocarbons, Chlorinated - metabolism; hydrophobicity; lindane; Lindane - analysis; Lindane - metabolism; lipid content; Mangrove; Marine and brackish environment; metabolites; molluscs; Organic Chemicals - analysis; Organic Chemicals - metabolism; Organic contaminants; Pesticides - analysis; Pesticides - metabolism; pollutants; polychlorinated biphenyls; Polychlorinated Biphenyls - analysis; Polychlorinated Biphenyls - metabolism; public health; reproduction; Rhizophoraceae; risk; seasonal variation; Seasonality; Seasons; sediments; Senegal; Shellfish; toxicity; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - metabolism; West Africa; wet season; Senegal; Africa; Organic contaminants; Shellfish; Mangrove; Estuary; West Africa; Seasonality; Brackish water environment; Edible mollusc; Estuaries; Zoobenthos; Concentration; Sediments; Persistent organic pollutant; Saloum; ACL; pollution; Senegal; anadara
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2011.04.012

► Mangrove sediments and molluscs are contaminated in PCBs, DDTs, and Lindane. ► Strong seasonal variations are linked to the wash-out of residues during rainy season. ► Patterns in DDTs suggest recent applications for public health emergencies in Senegal. ► No risk for human, especially local populations, through shellfish consumption.
The surface sediments, two bivalves (
Arca senilis and
Crassostera gasar) and three gastropods (
Conus spp.,
Hexaplex duplex and
Pugilina morio) from two Senegalese stations, Falia (Sine-Saloum Estuary) and Fadiouth (Petite Côte), were analyzed for their pollutant organic persistent contamination (polychlorinated biphenyls PCBs; organochlorinated pesticides OCPs; polybrominated diphenyl ethers PBDEs). Results revealed significant levels of PCBs, DDTs and lindane in mangrove sediments ranging from 0.3 to 19.1, 0.3 to 15.9, and 0.1 to 1.9
ng
g
−1
d.w., respectively. Among the other POPs analysed, only hexachlorobenzene, heptachlor and
trans-nonachlor for OCPs, as well as BDE47 and BDE99 congeners for PBDEs were detected at very low concentrations, generally not of concern. POP levels and patterns were in good accordance with literature data available for other tropical developing countries. A seasonal quantitative difference was highlighted with higher levels of PCBs and DDTs in sediments after the wet season, likely due to the strong wash-out of residues from inland to the marine ecosystems during the rainy season. The observed pattern of DDT and its metabolites pointed out probable recent applications of DDT for public health emergencies in Senegal. Exploited molluscs were exposed to the same POP compounds as those measured in sediments. They presented OCP levels within the same range as in sediments, while significant higher concentrations of PCBs were observed in shellfish soft tissues revealing a higher bioaccumulation potential mainly due to the lipophilicity of these compounds. Finally, the influence of the reproduction cycle on POP levels through lipid content variations was highlighted, minimizing potential differences in POP bioaccumulation between shellfish species. From an ecotoxicological and public health point of view, results from this study revealed that POPs in sediments from the Petite Côte and the Sine-Saloum Estuary would not cause toxic effects and impairments in molluscs from these regions, and that no potential risk exists for human, especially local populations, through mangrove shellfish consumption.