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Relationships Between Concentrations of Phytoplankton Chlorophyll a and Total Nitrogen in Estuaries: Implications for Development of Nutrient Criteria
Citation:
DETTMANN, E. H. Relationships Between Concentrations of Phytoplankton Chlorophyll a and Total Nitrogen in Estuaries: Implications for Development of Nutrient Criteria. Presented at Coastal and Estuarine Research Federation 20 Biennial Conference: Estuaries and Coasts in a Changing World, Portland, OR, November 01 - 05, 2009.
Impact/Purpose:
The purpose of this research is to develop relationships between concentrations of total nitrogen and phytoplankton chlorophyll a in estuaries to serve as a tool in developing estuarine nutrient criteria. This presentation describes chlorophyll a - nitrogen relationships that have been developed at AED for 10 U.S. estuaries, and implications of these results for development of nutrient criteria. Ranges of chlorophyll a and total nitrogen concentrations observed in these estuaries will be examined in the context of concentration thresholds that have been proposed or used as nutrient criteria.
Description:
Regression relationships between summer surface concentrations of phytoplankton chlorophyll a and total (inorganic + organic) nitrogen have been developed for four estuarine embayments and six riverine estuaries on the U.S. Atlantic and Gulf of Mexico coasts. All systems show spatial gradients in chlorophyll a and nitrogen concentrations and substantial year-to-year variability in chlorophyll a–nitrogen relationships. Averaging data by station over several summers makes it possible to compare these relationships among estuaries. Water clarity is an important parameter influencing the response of chlorophyll a to nitrogen. Similar analyses are underway for lagoonal estuaries. The focus of this presentation is on the implications of spatial concentration gradients and the characteristics of chlorophyll a–nitrogen relationships for development of nutrient criteria for estuaries. Included will be discussion of: 1) ranges of chlorophyll a and nitrogen concentrations observed in these systems in the context of concentrations that have been proposed or used in some systems as nutrient criteria, 2) implications of year-to-year variability in chlorophyll a–nitrogen relationships for development of nutrient criteria, and 3) implications of these results for classification of estuaries as a tool in development of nutrient criteria.