Aquatic Sciences Meeting, Albuquerque 2001

SS31 Integrated Approaches to Drainage Basin Nutrient Inputs and Inland/Coastal Eutrophication (Science and Society Connections)

Date: Thursday, February 15, 2001, Time: 2:45:00 PM

Location: Cimarron

Tobias, C, R, Ecosystems Center, Marine Biological Laboratory, Woods Hole, USA, ctobias@mbl.edu

Cieri, M, , Ecosystems Center, Marine Biological Laboratory, Woods Hole, USA,

Peterson, B, , Ecosystems Center, Marine Biological Laboratory, Woods Hole, USA,

Deegan, L, , Ecosystems Center, Marine Biological Laboratory, Woods Hole, USA,

Vallino, J, , Ecosystems Center, Marine Biological Laboratory, Woods Hole, USA,

Fry, B, , Coastal Ecology Inst., LSU, Baton Rouge, USA,

ASSESSING WATERSHED NITROGEN INCORPORATION INTO A NEW ENGLAND ESTUARY DURING HIGH RIVERINE DISCHARGE: INITIAL RESULTS FROM A WHOLE ESTUARY 15N ENRICHMENT

Isotopically labelled nitrate (15NO3-) was added to the Rowley River Estuary, MA for 22 days to assess the transport, uptake, and cycling of terrestrially-derived nitrogen during a period of high river discharge and low phytoplankton activity. Despite large freshwater inputs and high tidal exchange, 15NO3 was not transported conservatively through the estuary. Isotopic enrichment of benthic microalgae and macroalgae exceeded 100 per mil indicating direct uptake of water column nitrate. The elevated 15N observed in sediment infauna and demersal fishes demonstrated that this N was passed on to higher trophic levels through the benthos. Water column PON showed negligible enrichment suggesting that water column sinks for nitrate are small relative to the benthos during this period of high flow and low phytoplankton growth.

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Aquatic Sciences Meeting, Albuquerque 2001

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