Issue Date: August 3, 2009
Dead Zone Smaller, But More Severe
The Gulf of Mexico's "dead zone," an area where oxygen levels are too low to support most forms of life, is smaller than expected but more severe this year, report scientists at Louisiana Universities Marine Consortium. Typically the dead zone area is limited to bottom waters just above the seafloor, but the current dead zone extends closer to the water surface than usual. Researchers predicted this year's dead zone would be comparable with last year's, with an area of about 8,000 sq miles, but unusual weather patterns reoxygenated the waters, resulting in this year's dead zone measuring only 3,000 sq miles. "These results at first glance are hopeful, but the smaller than expected area of hypoxia appears to be related to short-term weather patterns ... not a reduction in the underlying cause, excessive nutrient runoff," Robert Magnien, director of NOAA's Center for Sponsored Coastal Ocean Research, said in a statement. Each year, the dead zone forms in the Gulf of Mexico when excess nitrogen and phosphorus from agricultural runoff stimulate phytoplankton growth, causing low levels of dissolved oxygen.
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