Hypoxia Research Program


We research the relationship between nutrient pollution and ecosystem effects. The nutrient pollution from the Mississippi River fuels the Gulf of Mexico Hypoxic Zone.
Image by NOAA's Environmental Visualization Lab.

What is Hypoxia?

Hypoxia occurs when the amount of dissolved oxygen in water becomes too low to support most aquatic life (typically below 2 mg/l). Hypoxic waters can become dead zones – animals that can escape do and those that cannot often die. Over the long term, animal populations and commercial and recreational shellfish and fisheries decline.

Every year, over half of the U.S. estuaries experience natural or human-induced hypoxic conditions at some time. Evidence suggests that the frequency and duration of hypoxic events is increasing. Although nutrient (i.e. nitrogen and phosphorus) discharges to estuaries from processes such as weathering of bedrock are natural, inputs from agricultural runoff, the burning of fossil fuels and waste water treatment discharges have increased inputs to many times natural levels. Recognizing the threat to America's coastal ecosystems and economies, Congress reauthorized the Harmful Algal Bloom and Hypoxia Research and Control Act (HABHRCA).

Program Goals & Accomplishments

NCCOS has been studying Hypoxia and funding its research for nearly 25 years, implementing HABHRCA on behalf of NOAA.

Our goal is to provide timely and actionable scientific results for use by natural resource managers in an effort to restore and protect coastal ecosystems. We develop management strategies to reduce nutrient inputs into coastal waters, mitigate hypoxia, and protect coastal ecosystems.

For example, in the Gulf of Mexico, NCCOS-sponsored research has been used to set goals and prioritize actions for reducing the size of the hypoxic zone by the Gulf of Mexico/Mississippi River Watershed Nutrient Task Force. Our work is done in collaboration with state and federal government, academia and industry partners.

The main program accomplishments include:

Scientific Basis for Adaptive Management of Gulf of Mexico Hypoxia

Management actions strategies to reduce the size of the dead zone in the northern Gulf of Mexico are developed through the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force (Hypoxia Task Force, HTF). NOAA supported research during the 1990’s provided the foundation for an Integrated Assessment completed in 2000 that examined the distribution, dynamics and causes of the hypoxic zone. This scientific assessment provided the basis for the development of the Hypoxia Task Force’s 2001 Action Plan to reduce, mitigate, and control the hypoxic zone. NCCOS has met many of the science needs outlined in the 2000 Integrated Assessment and 2001 Action Plan through its Gulf of Mexico Ecosystems & Hypoxia Assessment (NGOMEX) program. Accomplishments from the NGOMEX program, including model development, forecasting, and monitoring research that is used to advance understanding of the causes and impacts of the hypoxic zone form the basis for scientific reassessments of the HTF Action Plan (e.g. the 2008 Gulf Hypoxia Action Plan). More information.

Quantifying the Impacts of Hypoxia to Living Resources

Understanding the impacts of hypoxia on living resources is an important focus of NCCOS-funded research in the Gulf of Mexico and other U.S. coastal waters. Although questions remain, this research has found the displacement of shrimp and fish from important habitat in the Gulf of Mexico as well as displacement and reductions in growth of fish from Delaware Inland Bays. Research on plankton, which forms the basis of the food chain, in Lake Erie, Chesapeake Bay, and the Gulf of Mexico, has found alterations to the relationship between plankton and predators that rely on them for food. Other NCCOS-funded scientists have found sub-lethal impacts to reproduction in fish using new molecular techniques, applied economic models to assess the socioeconomics of hypoxia impacts, and found reduced growth in shrimp exposed to hypoxia. An understanding of the impacts of hypoxia is critical to the development of effective management strategies.

Model Development and Forecasting the Dead Zone in the Gulf of Mexico

NCCOS has funded the development of several Gulf of Mexico models evaluating the causes of the Gulf of Mexico dead zone. These models in addition to others developed by EPA have been used to determine the percent reduction in nutrient loads (45% reduction in both nitrogen and phosphorus) needed to reduce the size of the dead zone to the HTF mitigation goal (5,000 km2). Since 2003, several of these models have forecasted the size of the dead zone in the Northern Gulf of Mexico. This prediction helps managers, policy makers, and the public better understand the relationship between Mississippi River nutrient loading and the magnitude of the dead zone. More information.

Measuring the Size of the Dead Zone

Every July since 1985, Nancy Rabalais of the Louisiana Universities Marine Consortium (LUMCON) with funding support from NOAA (COP, NCCOS), has mapped the size of the dead zone. Monitoring the size and geographic coordinates of the dead zone provide critical information both for measuring effectiveness of management strategies to reduce it but also as input to models being developed to explain the causes and forecast its ebb and flow over the course of the season. More information.

Modeling and Forecasting Hypoxia in the rest of U.S. Coastal Waters

The number of areas in coastal waters with dead zones has greatly increased since the 1960s. Four hundred systems worldwide, including 166 in US waters, now have documented dead zones. A review paper (SCIENCE Aug. 15, 2008) by NCCOS Coastal Hypoxia Research Program (CHRP)-funded researcher Robert Diaz of the Virginia Institute of Marine Science and Rutger Rosenberg of the University of Gothenburg, attributes this dramatic trend to increasing nutrient pollution and the burning of fossil fuels.

NCCOS-funded projects include hypoxia model development for Chesapeake Bay/Delaware Inland Bays, Narragansett Bay, and Green Bay, and one major watershed hypoxia project for Atlantic and Gulf coast estuaries. The project scientists are working closely with coastal resource managers to cater the model outcomes to information needed for coastal zone and nutrient management decisions. More information on the Coastal Hypoxia Research Program (CHRP).

Related Links

Learn more about NCCOS's Hypoxia Program

For more information, contact Trevor Meckley