HEAVY METALS BIOACCUMULATION IN SELECTED FISH SPECIES OF RIVER GONGOLA AT YAMALTU DEBA, GOMBE STATE, NIGERIA

This study was aimed to determine the level of heavy metals in water and the bioaccumulation factor of heavy metals in selected fish species (Bagrus bayad macropterus, Oreochromis niloticus and Clarias gariepinus) of River Gongola, Gombe State. Water and fish samples were collected from two locations for 18 months (Dec. 2021- May 2023). Water and fish samples were analysed for heavy metals (Cu, Cd, Cr, As, Ni, Mn, Fe and Zn) concentration using an Atomic Absorption Spectrophotometer (AAS). Bioaccumulation factors of heavy metals were determined in the selected fish species. The Cd, As and Mn concentrations in water exceeded the recommended standards. The levels of heavy metals varied significantly among fish organs. The liver had the highest concentration of most metals, followed by the gills and the muscles. The levels of heavy metals in the fish tissues were below standard limits. However, Zn was reported to have the highest concentration in all the tissues studied. The BAF values calculated were mostly < 1, indicating no probability of bioaccumulation except for Fe in B. bayad macropterus and C. gariepinus and As in C. gariepinus Periodic monitoring of the water and biota of the river is recommended to ensure the safety of these resources for consumer use.