The freshwater river crab, Potamonautes warreni, as a bioaccumulative indicator of iron and manganese pollution in two aquatic systems.

The aim of this study was to determine the potential use of the freshwater river crab, Potamonautes warreni, as a bioaccumulative indicator of iron and manganese pollution in aquatic ecosystems. Water and sediment analysis of the two study sites (Germiston Lake and Potchefstroom Dam) revealed that while levels of manganese were higher in Germiston Lake, iron concentrations were higher in Potchefstroom Dam. Metal analysis of P. warreni revealed that while the crabs from Potchefstroom Dam contained slightly higher iron levels than those from Germiston Lake, manganese concentrations in P. warreni from the latter site were significantly higher than those in the crabs from the former site. Iron and manganese levels in these organisms were influenced by the size, mass, and sex of the crabs on occasion, but these relationships were not always consistent at both of the sites. The results of this study clearly indicate that the ultimate levels of iron and manganese attained in P. warreni do vary depending on the site from which animals are collected. From this, it is suggested that these crustaceans be incorporated into biomonitoring protocols, particularly in areas that are subjected to elevated metal levels in the environment