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CCMA Releases Report Outlining Improved Methods for Evaluating Eutrophication
CCMA Releases Report Outlining Improved Methods for Evaluating Eutrophication
The National Oceanic and Atmospheric Administration's (NOAA's) Center for Coastal Monitoring and Assessment (CCMA) has published a report on assessing eutrophication in coastal water bodies, Improving Methods and Indicators for Evaluating Coastal Water Eutrophication: A Pilot Study in the Gulf of Maine. This pilot study of nine coastal bays, harbors, sounds and estuaries in the Gulf of Maine and five in the Mid-Atlantic region examines a number of items related to assessing eutrophication. The report is of interest to coastal and watershed managers, researchers, and others concerned with coastal water quality in the Gulf of Maine, as well as those interested in improving methods for evaluating coastal water quality in general.
Eutrophication, which occurs when an excess of nutrients, primarily nitrogen and phosphorus, enter a water body, is increasingly causing problems in the environment and for society. It can lead to: increases in dense blooms of phytoplankton, including "red tides" or harmful algal blooms; increases in zooplankton, increases in other types of algae; decreased water clarity; changes in seagrass beds and other submerged aquatic vegetation; changes in coral reefs; depletion of dissolved oxygen in the water; reductions in fish and shellfish harvests; fish kills; problems with water odor; and other adverse ecological and human use impacts.
Evaluating the extent of coastal eutrophication is a first step towards coming up with strategies to address it. The pilot study's goals were to improve upon existing methods previously used to assess eutrophication in the study area, develop a human-use indicator of coastal water health, apply the study methods to the 14 coastal water body systems, and use lessons learned from the study in updating the 1999 National Estuarine Eutrophication Assessment (NEEA).
The authors selected a modified version of the NEEA method, called the Assessment of Estuarine Trophic Status (ASSETS) method, for use in this study. To develop a human use-indicator, they used National Marine Fisheries Recreational Fish Catch data in conjunction with water quality data.
Twelve systems were evaluated for pressure, or overall human influence; state, or overall eutrophic condition; and response, or a prediction of future condition. For two systems, there was not enough data available to complete an assessment. The ASSETS results showed that the overall eutrophic conditions were low for two systems, moderate for seven systems, moderate high for two systems, and high for one system. Results were also broken down for each system for each variable studied: chlorophyll a, macroalage, dissolved oxygen, harmful algal blooms, and submerged aquatic vegetation loss. In addition, recreational fish catch was studied for each system, and linked to dissolved oxygen levels. At the broadest scale, recreational fish catch may serve as a good indicator of eutrophication in estuaries, but the results suggest that tailoring the indicator to a given system may work best. Among other recommendations, the authors suggest that this type of assessment be conducted every two to five years, in order to be able to examine trends over time, evaluate the success of management measures, and adjust actions as needed.
For the pdf of this report, click here.
For more information please contact Suzanne.Bricker@Noaa.Gov (NCCOS; 301-713-3020 x 139).