13. The Bioaccumulation of Elements through the Food Web in Lake Albert, Uganda

The importance of heavy metal assessments in African lakes is increasing due to human population growth and industrialization. Trace metal concentrations in freshwater fish from Sub-Saharan lakes have largely been found to be below the World Health Organizations permissible levels for human consumption. Lake Albert, Uganda, has seen substantial increases in human population and industry over the last 50 years, yet little is known about the bioaccumulation of potentially harmful elements through the food web. Recent work using stable nitrogen ( 15N) isotopes found mercury in Lake Albert fish to be biomagnifying to concentrations among the highest in Africa. Some fish exceeded 1000 ng/g ww, while the World Health Organizations recommended limit for mercury consumption is 200 ng/g ww. This study supplements the previous Lake Albert mercury work by examining Al, As, Cd, Cs, Co, Cr, Cu, Mg, Ni, Mn, Fe, Rb and Zn concentrations in various Lake Albert fish species using Inductively Coupled Mass Spectrometry. Biomagnification will be assessed by combining the metal analysis findings with fish trophic levels (estimated using 15N). The results of this study increase understanding of the bioaccumulation trends of many metals that have not yet been extensively studied in freshwater fish. Such information is critical to the development of effective aquatic management strategies and consumption guidelines for the Lake Albert area.