Gulf Dead Zone May Grow Larger Than Ever

LiveScience.com Yahoo News 15 Jul 08;

An annual dead zone that develops in the Gulf of Mexico could be larger than ever this summer, scientists said today.

The region, largely devoid of life, develops when an overgrowth of algae, fueled in part by agricultural runoff, robs the sea of oxygen, and other organisms can't survive.

The researchers are predicting the area could measure a record 8,800 square miles, or roughly the size of New Jersey. In 2007, the dead zone was 7,903 square miles. The largest dead zone on record was in 2002, when it measured 8,481 square miles. Researchers began taking regular measurements of the dead zone in 1985.

"The prediction of a large dead zone this summer is due to a combination of large influx of nitrogen and exceptionally high flows from the Mississippi and Atchafalaya rivers," said Louisiana State University scientist R. Eugene Turner.

The low oxygen, or hypoxic, area is primarily caused by high nutrient levels, which stimulates an overgrowth of algae that sinks and decomposes. The decomposition process in turn depletes dissolved oxygen in the water. The dead zone is of particular concern because it threatens valuable commercial and recreational Gulf fisheries.

Research indicates that the nearly tripling of nitrogen levels into the Gulf over the past 50 years from human activities has led to a dramatic increase in the size of the dead zone, according to a statement released today by NOAA, parent of the National Weather Service.

"The strong link between nutrients and the dead zone indicates that excess nutrients from the Mississippi River watershed during the spring are the primary human-influenced factor behind the expansion of the dead zone," said Rob Magnien, director of the NOAA Center for Sponsored Coastal Ocean Research. "This analysis will greatly inform the development of federal, state and local efforts to reduce the dead zone's size."