Average-size Gulf dead zone predicted

Average-size Gulf dead zone predicted

NOAA and research partners estimate hypoxic zone to be average size for Gulf of Mexico but a tad bigger than normal for Chesapeake Bay.

SCIENTISTS forecasted this year's Gulf of Mexico hypoxic zone to be about the size of the state of Connecticut, while the hypoxia in the Chesapeake Bay is projected to be slightly above average, the National Oceanic & Atmospheric Administration (NOAA) reported.

Based on NOAA-supported modeling and research partners from the University of Michigan, Louisiana State University, Louisiana Universities Marine Consortium, Virginia Institute of Marine Sciences/College, Texas A&M University and U.S. Geological Survey (USGS), the size of the Gulf of Mexico zone was estimated at 4,633-5,608 square miles. In comparison, the Gulf "dead zone" last year measured slightly larger, at 5,840 square miles.

For the Chesapeake Bay, the nation's largest estuary, the midsummer low-oxygen hypoxic zone is predicted to be 1.97 cubic miles, with the early-summer oxygen-free anoxic zone at 0.51 cubic miles and late-summer oxygen-free anoxic zone at 0.32 cubic miles.

The forecast was also pinpointed from models and NOAA-sponsored research from the University of Maryland Center for Environmental Science and the University of Michigan.

Furthermore, USGS estimates nutrient loading for the Mississippi River and Chesapeake Bay as part of the hypoxia calculations.

For the Gulf of Mexico, USGS estimated that 182,000 metric tons less nitrate (182,00 mt total) flowed down the Mississippi River into the northern gulf this May versus a year ago. Additionally, USGS estimated that 44,000 mt of nitrogen entered the Chesapeake Bay between January and May, compared to 36,000 mt in 2013.

"The USGS continues to conduct long-term nutrient monitoring and modeling," said William Werkheiser, USGS associate director for water. "This effort is key to tracking how nutrient conditions are changing in response to floods and droughts and nutrient management actions."

According to NOAA, hypoxic and anoxic zones are caused by runoff from point and nonpoint sources.

Since agriculture has been identified as a major nonpoint contributor of excess nutrients to the Gulf of Mexico, scientists from 12 Central U.S. states have entered into a partnership with the Mississippi River/Gulf of Mexico Watershed Hypoxia task force to reduce water pollution.

"This collaboration between land-grant universities and the task force will continue to promote effective implementation of science-based approaches to nutrient management. Our efforts will help farmers reduce nutrient losses to the environment," said Wes Burger, associate director of the Mississippi State University Agricultural Experiment Station and professor of wildlife ecology and management.

The actual measurement of oxygen levels in both bodies of water and the size of the 2014 Gulf hypoxic zone will be released in late July or early August, following the annual mid-July monitoring survey by the Louisiana Universities Marine Consortium. The final assessment for the Chesapeake Bay will be published in October.

Volume:86 Issue:27

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