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THE EFFECTS OF NITROGEN LOADING AND FRESHWATER RESIDENCE TIME ON THE ESTUARINE ECOSYSTEM
Citation:
Palter, AND E H. Dettmann. THE EFFECTS OF NITROGEN LOADING AND FRESHWATER RESIDENCE TIME ON THE ESTUARINE ECOSYSTEM. Presented at Estuarine Research Federation, New Orleans LA, September 25-30, 1999.
Description:
A simple mechanistic model, designed to predict annual average concentrations of total nitrogen (TN) concentrations from nitrogen inputs and freshwater residence time in estuaries, was applied to data for several North American estuaries from previously published literature. The objective of this study is to apply the model, which works well in large estuaries, to smaller systems. Data from 12 North American systems and a nutrient enrichment experiment in marine mesocosms suggest that the model predicts annual average nitrogen concentrations accurately (R2 = 0.93) and that these model results are correlated with chlorophyll a concentrations in the mesocosms (R2 = 0.94). The model was also applied to total nitrogen loads to side embayments of Buzzards Bay, Massachusetts. Data on these systems was limited to summertime concentrations, as opposed to the yearly averages the model was designed to predict. Still, the data suggest that nitrogen loading, corrected for freshwater residence time, is correlated to some estuary responses, including summertime TN concentrations and peak chlorophyll a concentrations. Finally, the model was applied to nine shallow New England estuaries and the output was plotted against peak macro algal biomass for each. In these systems, the modeled annual average nitrogen concentrations are correlated to the macroalgal response (R2 = 0.88). This analysis is preliminary evidence that this simple loading model may be a useful tool in eutrophication management because it may be able to predict estuarine trophic status using only nitrogen input and the freshwater residence time.