NEWSROOM
Louisiana Scientists Continue Study of Gulf of Mexico "Dead Zone"
Novemeber 2, 2009
A team of Louisiana scientists will continue their multi-decade studies of the Gulf of Mexico ‘Dead Zone’ with continued funding from the National Oceanic and Atmospheric Administration (NOAA). The focus in the coming years is modeling the causes of Gulf of Mexico hypoxia (low oxygen, often called a ‘Dead Zone’). Members of the group have been studying the low oxygen area for 25 years, making definitive connections between changes in Mississippi River basin landscape use, increases in Mississippi River nutrients such as nitrogen and phosphorus reaching the Gulf, and the continually increasing size and severity of the low oxygen (hypoxic) area.
The ‘dead zone’ forms each spring and summer along the Louisiana and upper Texas coasts, also in Mississippi coastal waters, as a result of the high freshwater discharge of the Mississippi River along with the highly enriched nutrient waters. The result in a physically layered coastal ecosystem is a burst of algal growth and subsequent decay that sucks most oxygen out of the lower water column and at the seabed.
Fishery resources are redistributed, full economic potential is diminished, and basic ecosystem functions such as biodiversity and food web structure are disrupted.
The research team, headed by Dr. Nancy Rabalais of the Louisiana Universities Marine Consortium, Dr. Eugene Turner of Louisiana State University and Dr. Don Scavia of University of Michigan, has been awarded $766,600 for the first of a five-year, $4 million project, subject to Congressional funding. The project is part of The Northern Gulf of Mexico Ecosystems and Hypoxia Assessment Program of NOAA entitled “Ecosystem Modeling of the Causes of Hypoxia.” The Louisiana group will be collaborating with a group centered at Texas A&M University that has been researching Gulf of Mexico hypoxia since 2003.
The LUMCON/LSU team has documented the size of the ‘dead zone’ since 1985, finding minimal areas when the Mississippi River delivers little fresh water and nutrients to sizes reaching 22,000 square kilometers (8,500 square miles), or the size of the Massachusetts. The bottom area of the hypoxic zone is related most closely to the nitrate-nitrogen load of the Mississippi River in the preceding spring. The 2009 dead zone was predicted to be among the largest ever recorded, but measurements showed it instead to be small in bottom area but much larger in the total volume and more severe than normal.
Members of the LUMCON/LSU team along with researchers from the University of Michigan have developed several predictive models that closely forecast the size of the summer hypoxic area.
The next steps for the research team are to refine the forecasting models for multiple scenarios of river discharge, nutrient loading, and physical conditions on different scales and for different times of the year. They will also further develop and refine the biological forcing mechanisms in a water quality based model inserted into a detailed dynamic model of the physics of the area where hypoxia occurs. The results of their studies will feed into nutrient management policy decisions for the watershed.
For more information, contact Nancy Rabalais at nrabalais@lumcon.edu or Eugene Turner at euturne@lsu.edu.
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