PARENT SESSION
Aquatic Toxicology II.
Bob Spehar, Rick Cardwell
Tuesday, November 14, 2000
8:00 AM to 12:00 PM
RH Center Ballroom
(103) Critical Review of Selenium Bioaccumulation in Aquatic Systems.
DeForest, David K.1, Brix, Kevin V.2, Adams, William J.3, 1 2 3
ABSTRACT- Selenium bioaccumulation in aquatic systems has been intensely studied over the past 25 years. Selenium is unusual in that it biotransforms to organo-selenium compounds that are readily assimilated by aquatic organisms and transferred up the food chain. Further, unlike most metals, vertebrates are more sensitive than invertebrates to selenium poisoning and the primary exposure pathway is the diet rather than the water column. Several researchers have implied that selenium may biomagnify in aquatic food chains. We have critically reviewed trends in selenium bioaccumulation and trophic transfer efficiencies in a wide range of aquatic habitats and food chains. In general, we have found that BAFs can be relatively high in invertebrates, but BAFs decrease in upper levels of the food chain that include vertebrates. Consequently, at the critical link between relatively insensitive aquatic invertebrates and sensitive vertebrates (fish and birds) that consume them, BAFs are almost always less than three and frequently less than one. This contrasts strongly with other contaminants such as mercury and DDT that are known to biomagnify in aquatic food chains and have relatively high BAFs at all trophic levels. Considering these data, we conclude that selenium does not bioaccumulate to the extent that it would create a concern for biomagnification.
Key words: selenium, bioaccumulation, biomagnification, aquatic life