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Factors Influencing Nitrogen-Chorophyll Relationships for Ten Estuaries on the U.S. Atlantic and Gulf of Mexico Coasts (NEERS 08)
Citation:
DETTMANN, E. H. Factors Influencing Nitrogen-Chorophyll Relationships for Ten Estuaries on the U.S. Atlantic and Gulf of Mexico Coasts (NEERS 08). Presented at New England Estuarine Research Society, Block Island, RI, October 16 - 18, 2008.
Impact/Purpose:
The purpose of the research described in this poster is to support the USEPA's Office of Water in development of nutrient criteria for estuaries. The poster describes development of mathematical relationships describing the response of phytoplankton concentrations to nitrogen for ten medium- to large-sized estuaries on the U.S. Atlantic and Gulf of Mexico coasts. The research also examines environmental factors that influence the sensitivity of phytoplankton response to nitrogen in estuaries, and is relevant to estuarine classification.
Description:
Regression relationships between summer concentrations of total (inorganic + organic) nitrogen and phytoplankton chlorophyll a in surface water have been developed for nine estuaries on the U.S. Atlantic coast and one adjacent to the Gulf of Mexico. Four of these systems are estuarine embayments and six are river-dominated estuaries. All systems show substantial year-to-year variability in relationships between total nitrogen (TN) and chlorophyll a. Freshwater inflow and temperature appear to influence year-to-year variability in response. Comparisons among estuaries are made using data averaged over several summers. Such relationships between TN and chlorophyll a are similar for all estuarine embayments, with any differences explained by water clarity. Relationships between TN and chlorophyll a concentrations for river-dominated estuaries are weaker and more system-specific than for estuarine embayments. However, when data for river-dominated systems are analyzed within zones having narrow ranges of water clarity, relationships for most systems strengthen and become more similar. Important factors influencing time-averaged response of chlorophyll a to TN in these ten systems are estuary type (embayment vs. river-dominated), and the magnitude and spatial distribution of water clarity.