Ecosystems: Nutrient Pollution and Hypoxia - Everything is Upstream of the Coast

Excessive nutrient inputs from human activities upstream of the coast, even hundreds of miles inland, can degrade the health of coastal ecosystems, especially estuaries. Nutrient pollution can cause a process referred to as eutrophication which can disrupt recreational activities, and over time, impair the ability of estuaries to support robust fisheries. Symptoms of eutrophication include hypoxia and associated fish kills, algal blooms, overgrowth of seaweeds, and loss of quality fish habitat, such as seagrass beds.


Percent of the nation’s major estuaries that displayed problematic symptoms of nutrient pollution in 2004.

Source: Bricker et al., 2007


Average size (in square miles) of northern Gulf of Mexico hypoxic “dead zone” from 2005-2009.

Source: NOAA, 2009b


Percent of nitrogen entering the Gulf of Mexico that comes from nonpoint sources.

Source: MS River/Gulf Task Force, 2008


Number of hypoxic “dead zones” documented around the nation’s coasts.

Source: Diaz and Rosenberg, 2008

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Download Nutrient Pollution Interactive Map and Data (1.3mb)

Source: Bricker et al., 2007. Effects of Nutrient Enrichment in the Nation's Estuaries: A Decade of Change
Note: The U.S. Territories, Alaska, and Hawaii were not included in this report.

About this Topic

The data in this topic, from a NOAA report on estuarine nutrient pollution, hypoxia and eutrophication, shows that at least 64 estuaries had moderate to high expression of overall eutrophic conditions in 2004. The overall conditions are based on concentration, timing, and spatial extent of chlorophyl-a, hypoxia, seaweed blooms, algae blooms, and loss of seagrass. The data show that all coastal areas in the U.S. have estuaries impacted by this problem. Two Case Studies are presented for this topic: Nutrient Pollution Impacts Coastal Residents and Economies and Dead Zones: A Common Symptom of Nutrient Pollution (including a video on hypoxia). There is also a Management Success Story on how Regulating Watershed Nutrients Improves Coastal Health.

Closer Look

Relevant Links

NOAA's National Estuarine Eutrophication Assessment

NOAA NCCOS Hypoxia and Nutrient Pollution Page

Mississippi River/Gulf of Mexico Watershed Nutrient Task Force