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Nutrients
Aquatic Stressors
Human activities over the past century have dramatically increased the amount of nutrients (nitrogen and phosphorous, in particular) that is introduced to our Nation's rivers, lakes, and coastal waters. This change has adversely affected the health of the natural environment and, in some cases, poses risks to human health.
The introduction of excess nitrogen and phosphorous promotes the growth of algae which eventually dies and sinks to the sediment. Naturally occurring bacteria subsequently decompose the algae in a process which consumes oxygen. When the bacterial demand for oxygen exceeds supply, oxygen levels in waters become inadequate to support the aquatic life living in that habitat and are described as "hypoxic." In addition to lowering oxygen levels, the increases in algal production that are caused by excess nutrients also adversely affect submerged aquatic vegetation and the populations dependent upon it and can induce changes in aquatic food webs.
EPA's research in this area will support development of nutrient criteria and standards aimed at protecting aquatic life from the adverse effects of nutrient loading. Specific attention will be focused on defining and quantifying the relationships between nutrient loading in coastal areas and three major ecological responses: decreased oxygen levels, loss of submerged aquatic vegetation, and changes in food webs. A long-term objective of this research is to expand scientists' understanding of how aquatic ecosystems function so that predictions can be made for systems about which only limited data exists. This objective will be met by developing classification schemes, standard measurement endpoints, and nutrient load-response models.
To learn more about nutrients, you may wish to visit Water Quality Criteria: Nutrients.
View information about the Implementation Plan for Nutrients Research within the Aquatic Stressors PDF file. (PDF, 197 pp, 3.21 MB, About PDF).
