LAUSR

Human activities have increased the release of selenium (Se) to aquatic environments, but information about the trophic transfer dynamics of Se in Canadian boreal lake systems is limited. In the present study, Se was added as selenite to limnocorrals (2 m diameter, 3000 L in situ enclosures) in a boreal lake in northwestern Ontario to reach nominal concentrations of 1 µg Se/L and 10 µg Se/L in triplicates each for 77 d, and three additional limnocorrals were controls with no Se added. Total Se (TSe) concentrations were determined in water, sediment, periphyton, benthic macroinvertebrates, zooplankton and reproductively mature female fathead minnows (Pimephales promelas; added on d 33) collected throughout (and at the end of) the exposure period. Mean measured water Se concentrations in the control, 1 and 10 µg/L treatments were 0.12, 1.0 and 8.9 µg/L. At the end of exposure (day 77), enrichment functions (EFs) ranged from 7,772 L/kg dry mass (dm) in the 8.9 µg/L treatment to 23,495 L/kg dm in the 0.12 µg/L treatment, and trophic transfer factors (TTFs) for benthic macroinvertebrates ranged from 0.49 for Gammaridae to 2.3 for Chironomidae. Selenium accumulated in fathead minnow ovaries to concentrations near or above the current US EPA criterion (15.1 µg/g dm for fish ovary/egg) in the 1.0 and 8.9 µg/L treatments, suggesting that, depending upon aqueous Se speciation, such exposures have the potential to cause Se accumulation in fish to levels of concern in coldwater, boreal lake systems. This article is protected by copyright. All rights reserved.