Metal Uptake and Bioaccumulation Potentials of Clarias Buthupogon and Heterobranchus Longifilis Collected from Asa River, Ilorin, Nigeria

摘要

Despite the existence of environmental legislations in Nigeria, aquatic environment has remained the sewer forwastes not minding its implications on the resident resources. Heavy metals pollution has become a worldwideconcern and this may be due to their ability to bioaccumulate in aquatic organisms which is a source of livelihood forhuman populations. Therefore, this work aimed at assessing heavy metal accumulation in Clarias buthupogon andHeterobranchus longifilis in Asa River, Nigeria. After reconnaissance survey, fish samples were collected usinghooks, traps and cast nets of various sizes twice monthly between April 2011 and March 2013 and were identifiedimmediately. The samples were processed and heavy metal concentrations were determined in the gill, liver andmuscle using atomic absorption spectrophotometer. Different metals were analysed in the gill, liver and muscle ofthe sampled fish species and the data obtained were subjected to statistical analysis using the T-test statisticalpackage to determine the level of difference between means. The results in (mg kg-1, dry weight) showed differentlevels of the analysed metals in the two fish species. The order of heavy metals accumulation in the two fish speciesare gills>liver>muscle and the levels of heavy metals bioaccumulation varied significantly (p<0.05) among season,sample locations, fish species and fish organs. All metals analysed vary significantly in the two fish speciesexamined, seasons and across sampling sites. The results suggest that Asa River has high pollution loads of theseheavy metals in fishes due to an indiscriminate of discharge of effluents in the river and could pose a health hazardsto man. Consequently, close monitoring of heavy metal loads in Asa River is recommended with a view ofminimizing the risks to health of the population that depend on the river for their water and fish supply