Abstract
Bioturbation is a natural process with potential to affect the dynamics of contaminants in sedimentary environments. In this investigation, two benthic organisms, the bivalve mollusc Notospisula trigonella and the eunicid polychaete Marphysa sanguinea were maintained at different densities in selenium contaminated sediments. Porewater and bulk sediment selenium concentrations were determined over a 20 day period. The benthos in this experiment appeared to raise the porewater concentrations with respect to the controls. Both animals accumulated selenium from the sediment mesocosms. Toxic effects were observed in both animals.