Developing an Indicator for Nutrient Supply in Tropical and Temperate Estuaries, Bays, and Coastal Waters Using the Tissue Nitrogen and Phosphorus Content of Macroalgae

EPA Grant Number: R827637
Title: Developing an Indicator for Nutrient Supply in Tropical and Temperate Estuaries, Bays, and Coastal Waters Using the Tissue Nitrogen and Phosphorus Content of Macroalgae
Investigators: Fong, Peggy
Institution: University of California - Los Angeles
EPA Project Officer: Hahn, Intaek
Project Period: August 1, 1999 through July 31, 2002
Project Amount: $399,335
RFA: Ecological Indicators (1999) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Ecosystems


Project Summary: Coastal eutrophication that results from increases in nutrient supply is a critical problem worldwide, causing major changes in marine populations and communities. The overall goal of this proposal is to develop an indicator that quantifies nutrient supply to tropical and temperate marine ecosystems using the tissue nitrogen (N) and phosphorus (P) content of macroalgae. In order to complement the present suite of indicators used to measure eutrophication, this indicator is targeted to be especially useful in systems where nutrients are supplied in pulses or those where non-point sources of nutrients such as groundwater or fluxes from the benthos are important.

Objectives: There are 5 specific objectives: 1) continue to identify and test potential species for use as indicators; 2) establish relationships between timing and magnitude of nutrient supply and accumulation of N and P in algal tissue; 3) establish quantitative relationships between environmental conditions, N and P supply, and tissue N and P; 4) develop a numerical simulation model based on experimental results that may be used as a "standard curve~ for the indicator to hindcast nutrient supply in the field; 5) field test the indicator.


There are four approaches: field collections, microcosm experiments in field and lab, simulation modeling, and field validation experiments. Field collections of macroalgae for analysis of tissue N and P will be conducted along the west coast of the US as well as in Florida and Puerto Rico. In southern California, the tissue N and P contents of Enteromorpha intestinalis have already been demonstrated to be a useful indicator for nutrient supply (Fong et al. 1998~. However, other species of algae need to be tested for areas outside southern California. Candidate species will demonstrate a clear relationship between nutrient supply and tissue nutrient content in the field. For each algal species identified, microcosm experiments will quantify the relationship between the magnitude and timing of nutrient supply, environmental and physical conditions (light, temperature, salinity, water motion), and tissue nutrient content. A simulation model will be developed and tested that synthesizes experimental and field data in order to hindcast nutrient supply based on tissue nutrients. This model will be used as a "standard curve" for the indicator, relating tissue N and P content to the magnitude and timing of nutrient supply under differing environmental conditions. Finally, field experiments will be conducted to test the indicator. Field experiments will entail placing caged subsamples of algae with known initial tissue N and P into regions with known nutrient supplies. While in the field, the subsamples of algae ~sample" the water, integrating nutrient supply over time. Tissue N and P content after this experimental deployment will be inputs to the simulation model, which will hindcast supply. Model predictions will then be compared to the known supply for that location. If the fit between model predictions and known nutrient loading rate is adequate, the model will be ready for use in systems without known loading rates. To protect the environmental integrity and sustainability of coastal ecosystems, it is essential that we have reliable measures of nutrient supply to these systems. Accurate measures of nutrient supply aid resource managers in assessing both the present risks to coastal ecosystem as well as to estimate future risks.

Expected Results:

The expected results of the proposed research will be to provide resource managers with a new tool to quantify nutrient supplies to several resource types, including estuaries, bays, and coastal waters. This new indicator will complement the suite of existing assessment approaches because with this approach we can better quantify non-point sources of nutrients such as loads from groundwater, benthic fluxes, and recycling. This indicator will benefit water quality managers that have been directed to set nutrient loading limits on marine systems that are considered "at risk" from eutrophication. With the present techniques, it is often extremely difficult to measure current nutrient loading rates. The proposed approach will aid in this process.

Publications and Presentations:

Publications have been submitted on this project: View all 50 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 22 journal articles for this project

Supplemental Keywords:

stressor, effluent, ecology, marine science, measurement method., RFA, Scientific Discipline, Geographic Area, Water, Ecosystem Protection/Environmental Exposure & Risk, Nutrients, Ecology, Ecosystem/Assessment/Indicators, Ecosystem Protection, State, Ecological Effects - Environmental Exposure & Risk, Ecology and Ecosystems, coastal ecosystem, aquatic ecosystem, environmental monitoring, hydrological stability, nutrient supply, nutrient transport, risk assessment, bays, marine ecosystem, algae, estuaries, stressors, macroalgae, tropical ecosystems, algal growth, coastal environments, Puerto Rico, effluent, ecosystem indicators, estuarine ecosystems, tropical storms, water quality, phosphorus, ecological indicators, California (CA), Florida, nitrogen

Progress and Final Reports:

  • 2000 Progress Report
  • 2001 Progress Report
  • Final Report