Aquatic Sciences Meeting, Albuquerque 2001

CS40 Nutrients, Primary Production, and Aquatic Ecosystems

Date: Wednesday, February 14, 2001, Time: 4:45:00 PM

Location: La Cienega

Doblin, M, A, Old Dominion University, Norfolk, USA, mdoblin@odu.edu

Baines, S, , SUNY Stony Brook, Stony Brook, USA, sbaines@ms.cc.sunysb.edu

Cutter, G, A, Old Dominion University, Norfolk, USA, gcutter@odu.edu

PARTICULATE SELENIUM IN THE SAN FRANCISCO BAY: CONCENTRATIONS AND IMPLICATIONS FOR FOODWEB ACCUMULATION

Selenium exists in multiple oxidation states and its bioavailability depends on this chemical speciation. Since 1986 we have been examining Se cycling in San Francisco Bay and more recently, the effect of Se speciation on its trophic transfer through the estuarine foodweb. The concentrations of total dissolved Se in the Bay have dropped 40% since 1986, mostly due to a decrease in selenite concentrations from oil refineries (45 to 15% of the total), with relatively little changes in selenate and organic selenide. Despite the decrease in dissolved selenite (the most bioavailable form for phytoplankton uptake), the amount of Se in suspended particles has remained constant, with concentrations ranging from 0.07 to 0.31 nmol/L (< 15% of the dissolved inventories). Most particulate Se is bioavailable organic selenide (derived from phytoplankton), however the high proportion of inorganic particles in SF Bay seston effectively “dilute” the total particulate Se available to consumers. Phytoplankton may contain large amounts of Se (ca. 20 - 500 µg/g Se), but the wide variability amongst species suggests that changes in species composition could have major implications for foodweb Se accumulation.

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Aquatic Sciences Meeting, Albuquerque 2001

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