Clarias anguillaris as a biological indicator of metal contamination of selected aquatic habitats of North-Western Nigeria

Abstract

Fish is a natural source of vitamins and mineral elements that are important in growth and immune system. Because of its habitat, Clarias anguillaris was used as a biological indicator of metal contamination in pollution prone aquatic environment. Gills, muscles, and bones from Clarias anguillaris were digested, and selected metals were quantified by atomic absorption spectrophotometry. Values were compared with WHO acceptable limits for sea foods. Generally, lead and cadmium concentrations were higher in season I samples of Rivers Bunsuru and Rima while same metals were higher in concentrations in season II samples of River Gagare and Goronyo Dam. For other metals and mineral elements, season I samples had higher concentrations while in other cases season II samples had higher concentrations. Tissue samples of season II from Goronyo Dam had highest lead contents than other samples from other rivers. Bioaccumulation of lead in fish tissues had occurred in the study sites due to uncontrolled mining activities. Lead replaces ∞ -aminolevulenic acid in haem biosynthesis and can cause anaemia in man being at the high trophic level of food chain.