Bioaccumulation of Selenium in Aquatic Ecosystems

ABSTRACT

Elevated levels of selenium have resulted in the degradation of several ecosystems and have been linked to reproductive impairment in important fish and waterfowl populations in several lakes and reservoirs, indicating the need for a better understanding of the bioaccumulation of selenium by aquatic organisms. Because space limitations prevent an exhaustive review, this paper focuses on the processes and mechanisms of bioconcentration and biomagnification. Comparative uptake and accumulation of selenite, selenate, and selenomethionine are examined, as well as the relative importance of waterborne and foodborne exposure. The observed toxicity of selenium in lakes and reservoirs is briefly discussed. Finally, this information is summarized, pointing out key trends in the uptake and accumulation of selenium. Perhaps the most important information generated by this review involves comparative metabolism of selenite and selenate; selenite is readily reduced and metabolized, while reduction and metabolism of selenate appears to be limited. A knowledge of the processes and factors influencing selenium bioaccumulation in aquatic organisms will be essential in the development of management strategies and treatment methods that can be used to ameliorate selenium contamination problems.