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Macroalgal Mediation of Dissolved Organic Nitrogen (DON) Dynamics in a Temperate Coastal Lagoon

EPA Grant Number: U915532
Title: Macroalgal Mediation of Dissolved Organic Nitrogen (DON) Dynamics in a Temperate Coastal Lagoon
Investigators: Tyler, Anna C.
Institution: University of Virginia
EPA Project Officer: McClure, Karen
Project Period: August 1, 1999 through August 1, 2002
Project Amount: $83,373
RFA: STAR Graduate Fellowships (1999)
Research Category: Academic Fellowships , Fellowship - Ecology and Ecosystems , Ecological Indicators/Assessment/Restoration

Description:

Objective:

The objective of this research project is to determine controls on dissolved organic nitrogen (DON) distribution and transformation across a nutrient gradient in a temperate coastal lagoon. More specifically, we aim to: (1) quantify the temporal and spatial patterns of standing stock concentrations and benthic-pelagic fluxes of dissolved nitrogen (N) and to partition the DON pool into specific compounds; (2) determine the role that macroalgae play in regulating DON fluxes; and (3) estimate the turnover rates of N by macroalgae.

Approach:

This study will take place along a nutrient input gradient in Hog Island Bay, a macroalgal-dominated lagoon at the Virginia Coast Reserve/Long-Term Ecology Research (VCR/LTER) site. Macroalgal mediation of benthic-pelagic dissolved inorganic nitrogen (DIN), total DON, urea, and amino acid fluxes will be measured experimentally using sediment cores incubated with and without macroalgae. The uptake capacity and Michaelis-Menten uptake parameters of specific DON compounds (urea, amino acids) will be estimated for a variety of different macroalgal species. The turnover of N by macroalgae will be estimated in field experiments using 15N labeled macroalgae.

Expected Results:

The results of the above experiments, combined with bimonthly field surveys of macroalgal biomass and sediment and water column nutrients, will enable the investigator to determine the importance of macroalgae to system-wide DON dynamics and nitrogen retention.

Supplemental Keywords:

nitrogen, N, dissolved organic nitrogen, DON, dissolved inorganic nitrogen, DIN, estuary, marine, ecosystem, aquatic, ecology, Atlantic coast, coastal, eutrophication, macroalgae, lagoons, primary production, organic matter, sediment-water interface, urea, algal bloom. , Ecosystem Protection/Environmental Exposure & Risk, Water, Scientific Discipline, RFA, Oceanography, estuarine research, Ecological Risk Assessment, algal blooms, Biochemistry, Ecology and Ecosystems, marine ecosystem, nutrient kinetics, water quality, coastal habitats, coastal resources, environmental indicators, macroalgal populations, coastal ecosystems, marine biology, bloom dynamics, nutrient enrichment, estuaries

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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