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A COMPARATIVE ANALYSIS OF NUTRIENT LOADING, NUTRIENT RETENTION AND NET ECOSYSTEM METABOLISM IN THREE TIDAL RIVER ESTUARIES DIFFERING PREDOMINATELY BY THEIR WATERSHED LAND USE TYPES.
Citation:
LEHRTER, J. C., J. R. PENNOCK, AND R. P. KIENE. A COMPARATIVE ANALYSIS OF NUTRIENT LOADING, NUTRIENT RETENTION AND NET ECOSYSTEM METABOLISM IN THREE TIDAL RIVER ESTUARIES DIFFERING PREDOMINATELY BY THEIR WATERSHED LAND USE TYPES. Presented at Estuarine Research Federation Conference , Norfolk, VA, October 16 - 21, 2005.
Description:
Abstract and oral presentation for the Estuarine Research Federation Conference.
Estuarine retention of watershed nutrient loads, system-wide nutrient biogeochemical fluxes, and net ecosystem metabolism (NEM) were determined in three estuaries exhibiting differing magnitudes of nutrient inputs. N and P loads were highest to the Weeks Bay estuary (agricultural watershed) followed by Fowl River (forested) and Dog River (urbanized). DIN was the dominant N input from the agricultural and urbanized watersheds while DON was the largest percent input from the forested watershed. Highest annual mean sediment denitrification and O2, PO43-and NH4+ fluxes occurred in Weeks Bay which also had the highest primary production. However the highest percentage of annual TN load lost to denitrification occurred in Dog River, 72%, which had the longest mean residence time (7 days). NEM increased along a trajectory associated with DIN:TOC loading which was found to positively correlate with the percentage of non-forested land-use in the watershed. Overall, Fowl River was net heterotrophic, -69 g C m-2 y-1 , Dog River was balanced between heterotrophy and autrophy, and Weeks Bay was net autotrophic, 24 g C m-2 y-1 . These NEM data fit quite well the empirical relationship describing NEM as a function of DIN:TOC loading in the few estuaries world-wide where these properties have been measured.