Baines, S. B.. State University of New York at Stony Brook, sbaines@ccmail.sunysb.edu
Fisher, N. B.. State University of New York at Stony Brook, nfisher@ccmail.sunysb.edu
Cutter, G. Old Dominion University, gcutter@odu.edu
Doblin, M. A.. Old Dominion University, doblin@odu.edu

 
UPTAKE OF DISSOLVED SELENIUM BY PHYTOPLANKTON: IS ORGANIC SELENIUM READILY INCORPORATED AND DO UPTAKE RATES DIFFER AMONG TAXA?
 
Selenium accumulates in estuarine food chains and sometimes reaches toxic concentrations in tissues of higher level consumers. The rate of dissolved Se incorporation into phytoplankton is needed to refine our predictions of Se tissue burdens in potentially sensitive organisms. Se has three common dissolved forms in oxic water: selenate, selenite and organic selenides. We used radioisotopic tracer techniques in laboratory culture experiments to assess the uptake of these Se species by an array of phytoplankton taxa. Phytoplankton were grown for 4-5 days in seawater enriched with varying concentrations of either 75-Se labelled filtered lysate of diatom cells, sodium selenite, or sodium selenate. Selenate incorporation by cells was insignificant compared to that of selenite and organic selenides. The bioconcentration of selenite varied among taxa, where diatoms and dinoflagellates incorporated >70% of the added selenite, but chlorophytes and cryptophytes incorporated <1%. The bioavailability of organic selenides was similar in magnitude to the availability of selenite for 5 different taxa. Our results suggest that incorporation of organic Se produced from organic matter decomposition as well as community composition of the phytoplankton should be considered when predicting Se concentrations in biota from dissolved concentrations.
 
Day: Friday, Feb. 5
Time: 02:15 - 02:30pm
Location: Sweeney Center
 
Code: SS28FR0215S