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RELATIONSHIPS BETWEEN SUMMER CONCENTRATIONS OF TOTAL NITROGEN AND CHLOROPHYLL A IN TEN COASTAL SYSTEMS IN THE EASTERN UNITED STATES
Citation:
DETTMANN, E. H., L. COOPER, L. MASON, K. HENRY, A. I. ERHUNSE, J. JACQUES, AND R. RAKAUSKAS. RELATIONSHIPS BETWEEN SUMMER CONCENTRATIONS OF TOTAL NITROGEN AND CHLOROPHYLL A IN TEN COASTAL SYSTEMS IN THE EASTERN UNITED STATES. Presented at New England Estuarine Society Spring Meeting, Hull, MA, April 06 - 08, 2006.
Impact/Purpose:
To examine relationships between summer average concentrations of total nitrogen and chlorophyll a concentrations in the near-shore Mid-Atlantic Bight and nine bays and estuaries in the eastern United States
Description:
We have examined relationships between summer (JuneAugust) average concentrations of total nitrogen (TN) and chlorophyll a (chl a) concentrations in the near-shore Mid-Atlantic Bight and nine bays and estuaries in the eastern United States: Boston Harbor/Massachusetts Bay, Long Island Sound, Delaware Bay, Tampa Bay, and Chesapeake Bay and four of its tributaries (the James, Rappahannock, Potomac, and Patuxent Rivers). All data are from publicly-available data bases. Both TN and chl a exhibit spatial gradients in each system, with concentrations in estuaries and bays typically highest at stations in the inner system, and low at stations near the seaward boundary. Data for all systems show strong positive correlations between average summer concentrations of TN and chl a at individual stations. Relationships for all systems show year-to-year variation, but when concentrations for individual stations are averaged over summers for multiple years (420 years for individual systems, depending on data availability), strong similarities among most systems are apparent. While the two northern-most systems show a somewhat higher chl a concentration for a given TN concentration than the more southerly systems, the slope of the relationship between TN and chl a for these two groups is similar. However, chlorophyll a in Delaware Bay seems largely independent of TN. The similarity among these diverse systems in the response of chl a to TN concentrations suggests that multi-year average concentrations of TN at a given station are a strong predictor of chl a concentrations, and that available screening-level models that can scale TN concentrations based on changes in loading from the watershed can provide useful estimates of resulting chl a concentrations for use in management applications.