Bioaccumulalation of some heavy metals in selected fish species in Shiroro Lake, Niger state, Nigeria

Abstract

The main purpose of this study was to determine heavy metals accumulation in the body tissue (gill, liver and tissue muscle) of the selected four fish species, Clarias gariepinus, Bagrus bayad, Tilapia zilli and Lates niloticus that are of commercial importance from Shiroro Lake, Niger State, Nigeria. Water samples were taken from five (5) stations in the lake, stations selected based on the entry points of effluent. The fish samples were bought from the landing site, Kwata Zumba monthly for 12 months (October 2018-September 2019). The weight of the fish species was recorded. One (1g) of the target organs (gill, liver and muscle tissue) of each sample were dissected out and digested, heavy metal concentration in them and that of water were determined using Atomic Absorption Spectrophotometer (AAS). The results showed that heavy metal concentrations in both water and fish tissues descended as follows Fe>Zn>Mn>Cu Pb.Clarias gariepinus liver recorded the highest concentration of Fe (13.76 mg/l) .while in March (peak of dry season) the mean value of Fe in water was 3.99 mg/l (the highest). The lowest mean values,0.80mg/l were recorded in September. There were significant difference (P<0.05) between dry and wet seasons mean values of heavy metals in both fish organs and water. The results showed presence of some heavy metals in the organs of the selected commercially important fish species found in Shiroro Lake. Muscle tissue of all the selected species accumulated less metals compared to their gills and livers