Dead zone in Gulf of Mexico continues to increase

By Nanci Velez
9/4/2007; The Daily Reveille (LSU, Online Edition)

The dead zone off the coast of Louisiana has grown to its largest size at 20,500 square kilometers, according to a July 2007 report by Louisiana Universities Marine Consortium.

Dead zones are places in aquatic environments that cannot sustain life because of oxygen levels. Low oxygen areas, or hypoxia, in the Gulf of Mexico were first seen in 1972.

Nan Walker, oceanography and coastal sciences professor, said hypoxia is prompted by the over blooming of phytoplankton, which is caused by certain chemicals and nutrients brought into the Gulf of Mexico by the Mississippi River. The bacteria that breaks down the phytoplankton is forced to use more oxygen in the process, reducing the amount needed by marine animals.

Terry Remaire, Louisiana Department of Wildlife and Fisheries biologist, said much blame has been placed on increased agricultural activity along the Mississippi River basin. Certain fertilizers used agriculturally in the Midwest contain nitrate, a nutrient which decreases oxygen in water.

"If you look at the broad picture, though, the real culprit is the increased population along the Mississippi River," Remaire said. "Now, just about everyone has some measure of guilt."

Walker said the hypoxia has severe consequences on marine life.

"Small animals that live here die," Walker said. "Fish can get away from these areas, but crabs and other bottom-dwelling creatures can’t. They’re forced to swim to the surface and try to survive."

The report issued by LUMCON indicated shrimp fishing in the Gulf of Mexico will see a decline because of the area’s lack of oxygen.

Remaire said environmentalists and researchers have put pressure on private agricultural and petrochemical companies to address the problem in the past 10 years.

The Environmental Protection Agency created the Hypoxia Task Force to reduce the size of the dead zone in the Gulf of Mexico by 50 percent by the year 2015.

The agency has put mandatory limits on the amount of specific chemicals – such as nitrogen, potassium and phosphate – found in other bodies of water that feed into the Mississippi River.

Remaire said while this is a step in the right direction, the dead zone will most likely increase in size, hindering these efforts.

"It’s possible at the end of 15 years we could see a drop in the effect, but the problem is of such magnitude that it will probably take a long time to see any result," Remaire said.

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