MP5 Novel Methods for Bioaccumulation Assessment
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1:20 PM - 4:40 PM, Monday
() Assessment of selenium biomagnification in an aquatic community using stable isotopes.
Unrine, J1, Hopkins, W1, Jackson, B1, Romanek, C1, Staub, B1, Paddock, L1, 1 University of Georgia Savannah River Ecology Laboratory, Aiken, SC, USA
ABSTRACT- Biomagnification of selenium (Se) in aquatic ecosystems could potentially increase the risk of Se toxicity in higher trophic level organisms relative to organisms occupying lower trophic positions; however, studies addressing the question of whether Se biomagnifies have produced conflicting results. In many previous studies trophic structure has been poorly defined, potentially confounding assessments of biomagnification. Furthermore, differences in carbon source for primary consumers (e.g. algal versus bacterial, terrestrial versus aquatic) are rarely considered, but could influence Se bioaccumulation patterns. In this study, nine species of aquatic organisms (including snails, clams, odonate larvae, fish, and amphibian larvae) were collected from a swamp contaminated by trace elements from coal combustion waste. Stable isotopes of nitrogen (
15N) and carbon (13C) were used to characterize trophic positions and carbon sources within the community. Significant differences in 15N, 13C, and total Se were found among species. Based upon an increase in 15N of approximately 2-3 ‰ through each trophic level, our collection of species represented 3-4 trophic levels. Mean 13C ranged from -20.0 to -27.5‰ among species, suggesting that primary consumers have multiple carbon sources in this contaminated swamp. Mean Se concentrations ranged from 6.60 to 24.50 
g/g dry mass among species. Through multiple regression analysis we found no relationship between Se body concentration and 15N; however, there was a statistically significant negative relationship between 13C and Se concentration. To our knowledge, this is the first study examining Se biomagnification using the stable isotope approach and suggests that while trophic level does not influence Se concentrations, Se accumulation may be related to differences in carbon source.
Key words: Stable isotope, Selenium, Biomagnification, Aquatic community