Corn boom could expand ‘dead zone’ in Gulf

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The dead zone typically begins in the spring and persists into the summer. Its size and location vary each year because of currents, weather and other factors, but it is generally near the mouth of the Mississippi.

This year, it is the third-biggest on record. It was larger in 2002 and 2001, when it covered 8,500 and 8,006 square miles respectively.

Soil erosion, sewage and industrial pollution also contribute to the dead zone, but fertilizer is believed to be the chief factor.

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Fertilizer causes explosive growth of algae, which then dies and sinks to the bottom, where it sucks up oxygen as it decays. This creates a deep layer of oxygen-depleted ocean where creatures either escape or die.

Marine life struggle to survive
Bottom-dwelling species such as crabs and oysters are most at risk, said Michelle Perez, an analyst with the Washington-based Environmental Working Group. "They struggle to survive," Perez said. "They can't swim away."

Crabbers complained at a meeting in Louisiana earlier this year that they pulled up bucket upon bucket of dead crabs.

Rota warned that if the corn boom continues, the Gulf of Mexico could see an "ecological regime change." The fear is that the zone will grow so big that most sea life won't be able to escape it, leading to an even bigger die-off.

"People's livelihood depends on the shrimp, fish and crabs in these waters," he said. "Already, some of these shrimpers are traveling longer and longer distances to catch anything."

Given the market pressure to grow corn, the Natural Resources Defense Council and others argue that the nation needs a comprehensive, federal approach to the problem.

Among the ideas floated: rules to force farmers to use fertilizers with more care, and the establishment of buffer zones to contain runoff.