Bioaccumulation of heavy metals and oxidative stress biomarkers response in <i>Anodonta marginata</i> from River Challawa Kano State, Nigeria

Abstract

The widespread contamination of aquatic bodies by heavy metals has engrossed worldwide attention due to their persistence and accumulative nature. The present study determined the bioaccumulation of some heavy metals which include Cadmium (Cd), Chromium (Cr), Copper (Cu), Lead (Pb), Manganese (Mn) and Nickel (Ni) in a bivalve mussel (Anodonta marginata) with their levels in sediment and water of Challawa River, Kano, Nigeria; metals were assessed using atomic absorption spectrophotometer. The oxidative stress biomarkers (Superoxide Dismutase, Catalase and Glutathione) were assessed using the tissues of mussels after homogenization. The water samples analyzed had mean concentrations of Cd (0.088mg/L), Cr (0.457mg/L), Pb (0.127mg/L) and Ni (0.101 mg/L) above the World Health Organization's permissible limits of 0.003, 0.05, 0.01 and 0.07 mg/L respectively. The levels of all the heavy metals in water, sediment and mussels between dry and wet seasons were not significantly different (p > 0.05). The trend of heavy metal levels in increasing order was Site B > Site C > Site A > Site D. The same trend in levels of SOD, CAT and GSH were observed which indicates antioxidant response as a result of heavy metal exposure. These results indicate that mussels stimulated the increase in antioxidant enzyme activities as an adaptive response to oxidative damage by metals. Such could pose a serious consequence given the massive population that relies on the river as a source of water, irrigation and fishing activities.