Author(s)

Hodabalo Dheoulaba Solitoke^1*, Komlan Mawuli Afiademanyo^2*, Kamilou Ouro-Sama¹, Gnon Tanouayi¹, Tchaa Esso-Essinam Badassan¹, Kissao Gnandi¹

¹Laboratory of Waste Management, Treatment and Valorization, Faculty of Sciences, University of Lomé, Lomé, Togo.
²Laboratory of Animal Ecology and Ecotoxicology, Department of Zoology and Animal Biology, Faculty of Sciences, University of Lomé, Lomé, Togo.

The Lake Zowla-Aného lagoon hydro system, located on the southeast coast of Togo, is very exposed to metal contamination as it receives a huge amount of untreated domestic and industrial effluents from Aného City and the phosphorite treatment plant at Kpémé. This study aims to assess the concentrations of seven heavy metals and their bioaccumulation status in soft tissues and shells of the mangrove oyster (Crassostrea gasar) collected from this aquatic environment. Samples were collected in January, April and July 2017 at two stations and analyzed using flame atomic absorption spectrophotometry. Results indicate that the waters are contaminated by Cd, Pb and Cr with average concentrations that are significantly above WHO standards. At both locations, the contents of the trace elements (except Cr) in oysters’ soft tissues were significantly higher than those in the shells. In the soft tissues, the concentration of Cr, Cu, Zn, As, Cd, Hg, and Pb ranged (in mg·kg^-1) from 4.33 to 23.14, 93.4 to 366.7, 455.68 to 1384.15, 0.11 to 1.34, 16.42 to 62.6, 0.05 to 0.473 and 0.39 to 21.08, respectively. Furthermore, statistical analyses showed marked differences in mean concentrations between sampling time on the one hand, and between sampling locations on the other hand (p < 0.05). The highest metal concentrations were recorded in oysters collected in June at Zalivé whereas the lowest values were recorded in April at Zowla. Based on BCF results in the lagoon system, the oyster C. gasar can be used as a biomonitor of Zn, Cd, Cu and Hg exposure. Finally, the Cd, Pb, As, Zn and Cu concentrations in soft tissues and were found to be significantly higher than the permissible limit for human consumption according to WHO and FAO and thus pose a threat to human health.

Bioaccumulation, Oyster Crassostrea Gasar, Trace Elements, Aného Lagoon, Lake Zowla, Togo

Solitoke, H. , Afiademanyo, K. , Ouro-Sama, K. , Tanouayi, G. , Badassan, T. and Gnandi, K. (2021) Trace Element Concentrations in Soft Tissue and Shell of the Mangrove Oyster (Crassostrea Gasar Dautzenberg, 1891) from the Lake Zowla-Aného Lagoon Hydro System (Southern Togo). American Journal of Analytical Chemistry, 12, 471-492. doi: 10.4236/ajac.2021.1212030.