Biodeposition and Biogeochemical Processes in Shallow, Mesohaline Sediments of Chesapeake Bay

dc.contributor.advisorCornwell, Jeffrey Cen_US
dc.contributor.authorHolyoke, Rebecca Raeen_US
dc.contributor.departmentMarine-Estuarine-Environmental Sciencesen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.description.abstractStocks of the eastern oyster, Crassostrea virginica, have been declining in Chesapeake Bay since the late 19th century, and current strategies involve restoring culture of Crassostrea virginica on-bottom and in devices suspended within the water column. Sub-tidal suspension culture of Crassostrea virginica in Chesapeake Bay occurs mostly in sheltered inlets and tidal creeks and, thereby, has the potential to influence shallow water biogeochemical processes. To assess the influence of Crassostrea virginica biodeposits and benthic microalgae on sediment nitrogen and phosphorus exchange, field studies with Crassostrea virginica held in aquaculture floats and laboratory experiments were conducted. Enhanced organic nitrogen deposition from Crassostrea virginica biodeposits led to gradual increases in surface sediment nitrogen and pore water ammonium concentrations; however, modifications to pore water concentrations were not always expressed at the sediment-water interface. Benthic microalgae often modulated the influence of biodeposits on sediment nitrogen exchange but, as observed in laboratory experiments, the supply of nitrogen from Crassostrea virginica biodeposits may exceed their biological demand. Organic carbon from biodeposits had varying influences on aerobic respiration but consistently stimulated anaerobic metabolism. Shifts in net phosphorus exchange were driven by this anaerobic remineralization and concentrations of iron and manganese oxy(hydr)oxides, with transitions in fluxes coinciding with changes in benthic photosynthesis and oxidation of surface sediments. Manganese and iron oxy(hydr)oxides from biodeposits supported incorporation of added phosphorus and prevented exchange at the sediment-water interface in the absence of iron-sulfide mineral formation. Differences in the response of shallow water sediments to Crassostrea virginica biodeposits were due to the quality and quantity of biodeposits supplied, as well as the spatial and temporal variability within these sediments. Initial conditions and corresponding reference sediments illustrated the potential for sediment biogeochemistry and nutrient exchange from tidal creek sediments to vary spatially and temporally on relatively small scales. Factors influencing variability within tidal creek sediments were related to shifts in riverine freshwater inputs, macroalgal blooms, nutrient concentrations in overlying waters, and bioirrigation from the clam, Macoma balthica.en_US
dc.format.extent2195877 bytes
dc.subject.pqcontrolledEnvironmental Sciencesen_US
dc.subject.pquncontrolledBenthic microalgaeen_US
dc.subject.pquncontrolledChesapeake Bayen_US
dc.subject.pquncontrolledCrassostrea virginicaen_US
dc.subject.pquncontrolledsediment biogeochemistryen_US
dc.subject.pquncontrolledshallow water sedimentsen_US
dc.subject.pquncontrollednitrogen and phosphorus fluxesen_US
dc.titleBiodeposition and Biogeochemical Processes in Shallow, Mesohaline Sediments of Chesapeake Bayen_US


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