Evaluation of heavy metals contamination in Rabbit Fish (Signus Sutor) from selected landing sites in Zanzibar, Tanzania

Abstract

The increase of heavy metals concentrations in aquatic and terrestrial environments andtheir toxicity is of global concern. The bioaccumulation of toxic metals in fish poses aserious risk to human health when consumed. This study assessed the quality of Rabbitfish (Signus Sutor) and their associated health risks from four landing sites (namelyMalindi, Mazizini, Kizimkazi and Matemwe) in Zanzibar. The concentrations of toxicmetals, including Lead (Pb), Cadmium (Cd), Copper (Cu), Chromium (Cr), Nickel (Ni),and Arsenic (As), in the fish muscle were scrutinized using inductively coupled plasmaoptical emission spectrometry (ICP-OES). The detected mean concentration (mg/kg) of Pb,As, Cr, Cd, Cu, and Ni at Malindi were 0.25±0.14, 2.22±0.44, 0.02±0.02, 0.01±0.00, 0.02±0.02and 0.00±0.00 respectively; at Kizimkazi were 0.39±0.39, 2.30±0.44, 0.11±0.01, 0.07±0.04,0.17±0.13 and 0.15±0.04 respectively: at Matemwe were 0.38±0.12, 0.52±0.14, 0.04±0.02,0.05±0.01, 0.65±0.21 and 0.09±0.03 respectively; and Mazizini were 0.21±0.12, 5.56±1.37,0.02±0.02, 0.03±0.01, 0.05±0.02 and 0.15±0.05 respectively. The mean concentration levelsdetected for all the elements in the fish gathered from all four landing sites were belowinternational and local maximum (FAO/WHO) permissible limits for humanconsumption, except for Arsenic (As) and lead (Pb). The study also investigated therelationship between fish size and metal concentration which shows a positive correlationfor Cu and Ni. However, it was negative for the remaining metals, possibly due toecological and metabolic differences. The study emphasizes the necessity for regularmonitoring of the marine environment and enforcement of hygienic regulations, as well asthe treatment of land-based pollutants before they are discharged into the marineenvironment to protect fish quality.