Gulf of Mexico ‘dead zone’ could become one of largest recorded

By By Brant James
Jun 25, 2009

Scientists predict that the "dead zone" off the coast of Louisiana and Texas, where seasonal oxygen levels become insufficient to sustain animal life in deeper waters, could be one of the largest ever.

Results of a first survey were released last week by the National Oceanic and Atmospheric Administration. A second survey of the area is scheduled to begin today by teams from the Louisiana Universities Marine Consortium, Louisiana State University and the University of Michigan.

The first survey led them to estimate the dead zone could measure from 7,450 to 8,456 square miles, encompassing an area about the size of New Jersey. A record 8,484-square-mile expanse set the record in 2002.

The dead zones are created when nutrient-rich runoff — mostly from the numerous farms along the Mississippi River or its tributaries — flows into the Gulf of Mexico, prompting an algae bloom that consumes much of an area’s oxygen at lower levels when it is consumed by fish or decomposes on the bottom.

Times graphic explaining how the Dead Zone forms

National Oceanic and Atmospheric Administration video.