Bioaccumulation of chromium, copper and iron in the organs and tissues of Clarias gariepinus in the Olifants River, Kruger National Park

An investigation was undertaken into the bioaccumulation of Cr, Cu and Fe in the gills, liver, muscle and skin of the fish Clarias gariepinus from two sites on the Olifants River in the Kruger National Park. During 1994, four surveys (February, May, July and November) were undertaken. Metal bioaccumulation was analysed using atomic absorption spectrophotometry and was then applied to differentiate between the concentrations found at the two locations, and between all of the surveys. The greatest concentration of Cr was detected in the gills, suggesting that this was the prime site of absorption and loss of Cr to and from the aquatic environment. The concentrations of Cu and Fe were highest in the liver, which is a storage and detoxification organ for metal, followed by the gills. Mamba and Balule generally showed very little difference in the concentration of bioaccumulated metal. However, the gills as in the case of Cr generally showed high concentrations at Mamba, while the liver as in the case of Fe, showed consistently higher concentrations at Balule. The possible effects that temperature, pH, hardness and salinity have on the individual metals, as well as bioaccumulation of these metals, are discussedin detail. The continuous monitoring of the quality of water in the Olifants River is imperative for the future sustainability of the Kruger National Park.