Accumulation of metals in three fish species from the Yaounde Municipal Lake in Cameroon

Metals are dangerous to aquatic organisms and they can bioaccumulate in the food chain and represent risk for humans. In order to appraise their levels in fish species, concentrations of various elements including Na, Mg, K, Ca, Al, Fe, Mn, Cr, Ni, Co, Cd, Cu, Pb, Zn, Ba, and Sr were determined in the muscles and gills of three fish species (Oreochromis niloticus, Sarotherodon galilaeus, and Clarias sp.) which are more fished and consumed in the Yaounde Municipal Lake, Cameroon. According to chemical results of the fish samples analyzed by ICP-AES, the concentrations of metals (mg kg−1, wet tissues) in those fish tissues varied as follows for the muscle (and gill) Na 1480–3780 (4180–9310), Mg 897–1250 (843–1450), K 9600–18,500 (6020–10,400), Ca 430–3900 (22,200–62,400), Al 8.10–615 (113–951), Fe 12.0–725 (307–1160), Mn 1.61–30.1 (14.3–433), Cr 1.58–267 (0.31–35.4), Ni 0.16–1.85 (1.06–2.82), Co 0.10–0.47 (0.07–0.16), Cd 0.11–0.23 (0.10–0.22), Cu 0.59–5.13 (1.31–5.13), Pb 1.11–5.12 (2.56–5.74), Zn 15.4–47.2 (45.3–69.2), Ba 0.61–51.15 (0.35–83.2), and Sr 2.31–5.74 (2.09–5.75). The results revealed that Na, Ca, Zn, Fe, and Mn were higher concentrated in the gills than in the muscles, while K, Cr, Ni, Co, and Cd were more concentrated in the muscles of the species. In addition, all the elements were bioaccumulated in the fish species and the bioaccumulation factors (BAFs) were decreased in the following order: Cr > Ni > Zn > Al > Ca > Pb > Mn > Ba > K > Fe > Mg > Cu > Na > Sr > Co > Cd. Compared to international standards, Pb, Cd, Cr, Ni, and Zn were over the recommendations of the European Community, WHO, and Norwegian guidance values for human health. Therefore, fishes from the Yaounde Municipal Lake are not advised for human consumption as toxic elements might be taken above the recommended levels.