SS3.19 Role of Benthic Communities in the Cycling and Balance of Nitrogen in Bays and Estuaries
Date: Friday, June 14, 2002
Time: 11:00:00 AM
Location: Oak Bay
 
BreedGA, Department of Oceanography, Texas A&M University, College Station TX, USA, gbreed@ocean.tamu.edu
Jackson, G, A, Dept. of Oceanography, Texas A&M University, , , 
Richardson, T, L, Dept. of Oceanography, Texas A&M University, , , 
 
INVERSE ANALYSIS OF CARBON FLOW THROUGH PLANKTONIC FOOD WEBS OF THE MISSISSPPI RIVER PLUME
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An inverse modeling approach was used to examine carbon flows and trophic interactions in the planktonic ecosystem of the Mississippi River plume. Four interconnected sub-regions of the plume were modeled, extending along the salinity gradient from a turbid, eutrophic, upstream region to a relatively clear, near-oligotrophic, downstream region. Models were constructed using data collected during large-scale investigations (e.g. NECOP, LASER, LATEX) in this region during four seasons. In spring, summer, and autumn, results indicate that the ecosystem is net autotrophic, and that carbon export to deep water far exceeds rates measured by field sediment trap data. In winter, model results suggest that the plume ecosystem is net heterotrophic, and that carbon inputs from the river are required to sustain measured bacterial production. High rates of phytoplankton derived detritus production were predicted by the model, indicating that current grazing estimates may not include all grazing related losses.