Aquatic Sciences Meeting, Albuquerque 2001

PC07 Spatial and Temporal Connections

Date: Wednesday, February 14, 2001

Location: Southwest Hall

Parker, A, E, University of Delaware, Lewes, USA, parkera@udel.edu

Sharp, J, H, University of Delaware, Lewes, USA, jsharp@udel.edu

DIFFERENTIAL CARBON AND NITROGEN TRANSFER IN THE ESTUARINE MICROBIAL LOOP: THE ROLE OF NITROGEN CONCENTRATION AND QUALITY

The importance of the microbial loop has been extensively studied in oceanic environments but is still relatively unresolved in estuarine waters. In estuaries, spatial and temporal variability in environmental conditions makes predictions about bacterial growth efficiency difficult. From our microbial biogeochemical research over the past two decades, we have gained insight into the factors that are most likely to affect bacteria / phytoplankton linkages via the DOM pool. Primary production in the Delaware is most heavily influenced by light and nitrogen availability, while bacterial production is influenced by allochthonous DOM input in the urban river and autochthonous primary production in the lower bay. Using dual tagging techniques with stable carbon and nitrogen isotopes we have investigated the importance of ammonium and nitrate availability as well as light on the transfer of autochthonous production to bacterial biomass. Preliminary results show that nitrogen quality and availability influence the transfer of autochthonous carbon and nitrogen differently. This uncoupling of organic carbon and nitrogen cycles within microbial foodwebs may have important biogeochemical consequences and should be considered with respect to management of coastal eutrophication.

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Aquatic Sciences Meeting, Albuquerque 2001

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