Aquatic Sciences Meeting, Albuquerque 2001

PC19 Benthic Processes and Ecology

Date: Thursday, February 15, 2001

Location: Southwest Hall

Heyes, A, , University of Maryland, Chesapeake Biological Laboratory, Solomons, USA, heyes@cbl.umces.edu

Clark, M, , Lycoming College, Williamsport, USA, clamegh@lycoming.edu

Gilmour, C, C, Academy of Natural Sciences, Estuarine Research Center, St. Leonard, USA, Gilmour@acnatsci.org

Mason, R, P, University of Maryland, Chesapeake Biological Laboratory, Solomons, USA, mason@cbl.umces.edu

Riedel, G, R, Academy of Natural Sciences, Estuarine Research Center, St. Leonard, USA, griedel@acnatsci.org

Connell, D, B, University of Maryland, Chesapeake Biological Laboratory, Solomons, USA, Connell@cbl.umces.edu

THE EFFECT OF SEDIMENT DISTURBANCE IN ESUARINE SEDIMENT

Disturbance can temporarily upset the established redox chemistry and nutrient balance of sediments. The primary methylators of Hg are sulfate reducing bacteria, therefore their activity and ability to methylate are limited by the supply of sulfate, carbon and Hg. In the Patuxent River, an estuary of the Chesapeake Bay, we simulated disturbance associated with activities such as boating and crabbing in mesocosms. Sediment was disturbed to a depth of 5 and 10 cm, on two occasions after which Hg, MeHg concentrations in sediment, sulfate, sulfide, Fe and Mn concentrations in porewater and methylation rates (using stable isotopes) were followed. In the mesocosms where sediment was disturbed to 10 cm, the MeHg concentration increased significantly above the controls from 0.1 to 0.3 ng/g dry weight over a one month period. Sulfate concentrations remained unaffected whereas sulfide concentrations increased slightly. In this poster we will discuss the reasons for the increase in MeHg concentrations.

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Aquatic Sciences Meeting, Albuquerque 2001

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