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Gulf of Mexico's 'Dead Zone' Larger Than Predicted, According to New NOAA Study


Idle shrimp boats float at the docks of Joshua's Marina in Buras, Louisiana, May 17, 2010.

NOAA-supported scientists on Tuesday reported that this year’s “dead zone” in the Gulf of Mexico is larger than originally predicted, at more than 16,000-square kilometers, or about the surface area of Lake Ontario and Lake Erie combined.

NOAA forecasted in June that the hypoxic zone — an area with little to no oxygen to support marine life — would be 12,600 square kilometers, which would have been smaller than the five-year average. The actual size proved far larger.

The annual hypoxic zone survey was conducted aboard the R/V Pelican research vessel from July 25 to August 1 by scientists from Louisiana State University and the Louisiana Universities Marine Consortium.

The researchers gathered data on the dead zone’s location, as well as oxygen and salinity levels. This evidence is vital for NOAA to refine its models and study how to decrease the size of the hypoxic area.

A Mississippi shrimp boat heads out of the harbor on the first day of shrimp season in Biloxi, Mississippi on June 3, 2010.
A Mississippi shrimp boat heads out of the harbor on the first day of shrimp season in Biloxi, Mississippi on June 3, 2010.

The dead zone’s expansion is believed to be driven by pollutant runoff from farms and cities contaminating the Mississippi River, which flows into the Gulf of Mexico and stimulates oxygen-consuming algae growth. NOAA aims to minimize the loss of habitat caused by the phenomenon for living resources like commercially harvested fish and diminish the hypoxic zone’s influence on local economies.

The Interagency Mississippi River/Gulf of Mexico Hypoxia Task Force utilizes the survey’s data to evaluate nutrient runoff and create solutions to lessen contaminants in the watershed. The Hypoxia Task Force collaborates with local farmers and corporations to execute water quality projects.

“Our nation’s farmers provide the food, the fuel, the fiber, that sustains our families, that sustain our nation, and they are true leaders in environmental stewardship and water management,” said Radhika Fox, co-chair of the Hypoxia Task Force.

Government investments assist in the task force’s goal of reducing the dead zone, like the USDA’s $38 million contribution to small watersheds, and Section 319 of the Clean Water Act that provides grants to professionals who seek to mitigate waterway pollutants.

According to Nancy Rabalais of Louisiana State University and principal investigator of the survey, the effects of climate change could alter the dead zone. Rabalais stated that rising temperatures and greater precipitation will increase the Gulf’s “stratification, or the layering of the surface layer over the bottom layer, making that difference much stronger and preventing oxygen from the surface getting back down to the bottom.”

Forecasting methods used by NOAA to measure the hypoxic zone may be impacted by climate change because of their reliance on average coastal weather conditions. Current practices may require adaptation as ocean temperatures rise and extreme weather events increase.

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