The Gulf of Mexico's so-called Dead Zone is expected to be a record 8,543 square miles this year and stretch into waters off Texas, said Nancy Rabalais, chief scientist for a study team at the Louisiana Universities Marine Consortium. Researchers are measuring the zone this week from boats.
''This is an area the size of New Jersey or potentially bigger where nothing can live,'' said Matt Rota, a program director at the Gulf Restoration Network, a coalition of environmental and civic groups. ''If this were happening in the middle of the country, people would be outraged.''
Corn fuels the zone because it requires more nitrogen-based fertilizer than crops such as soybeans, said Eugene Turner, a Louisiana State University oceanographer. Nitrogen and other nutrients eventually reach the Gulf, feeding microscopic organisms that deplete oxygen levels as they die and decompose on the sea floor. Shrimp and fish suffocate unless they escape.
Ethanol, a form of alcohol made from vegetable matter, is distilled mostly from corn in the U.S. Less polluting than gasoline, it's at the center of President Bush's plan to reduce reliance on imported oil.
The Dead Zone, also known as an hypoxia zone, is an annual phenomenon that lasts several months and usually peaks around late July. Discovered in the 1970s, it may have existed for a century. The area has about doubled in size since scientists began studying it in 1985.
The zone could be catastrophic for the northern Gulf of Mexico's $2.6-billion-a-year fishing industry, Rota said. At some point, he said, the zone might extend too far out for any shrimp or other creatures on the sea floor to escape.
Louisiana's fishing industry is the second-largest in the U.S., behind Alaska's. It has the largest catches of shrimp, oysters and crawfish, according to state figures. Louisiana is losing shrimpers, though. The number of shrimp fishermen licensed in the state has declined 40 percent since 2001.
Landings of brown shrimp in both Louisiana and Texas declined steadily after peaking at 103.4 million pounds in 1990, sliding as the hypoxia zone expanded, according to a 2001 study by Roger Zimmerman and James Nance of the National Oceanic and Atmospheric Administration.
The study found that the larger the zone, the smaller the shrimp catch. The average size of catches by weight dropped about 23 percent between the late 1980s and the 1990s.
An Environmental Protection Agency task force of scientists, state agencies and federal agencies set a goal in 2001 of reducing the Dead Zone to 2,000 square miles.
Little has been done with the group's recommendations, Rota said. Steps should include giving farmers more incentives to cut fertilizer runoff and reducing pollution from wastewater-treatment plants, he said.
The drumbeat of support for ethanol, backed by subsidies, puts that goal of reducing the zone further out of reach, Rabalais said. Refiners, fuel distributors and retailers receive a federal tax credit on each gallon of ethanol blended with gasoline, and every state except Alabama offers additional subsidies.
''The rah-rah sort of drowns out the environmental side,'' she said. ''If our federal government subsidizes more corn, they're working against water quality.''
Ron Litterer, first vice president of the National Corn Growers Association, is among farmers who planted more of the crop this year. On his farm near Greene, Iowa, where he used to split his 1,500 acres evenly between corn and soybeans, this year he devoted two-thirds to corn.
''We certainly want the family farmers to do well, but not at the expense of our natural resources in Louisiana and our family fishermen,'' said Tracy Kuhns, executive director of the Louisiana Bayou Keeper, a water-quality group. ''It just seems there ought to be ways to reduce nitrogen use and purify that runoff prior to it making its way into the river.''
The Gulf of Mexico isn't the only body of water with a dead zone. The North Sea, the Chesapeake Bay and others also are afflicted. Hypoxia is blamed for the collapse of lobstering in Norway's Kattegat and the loss of fisheries in the Black Sea and Baltic Sea.
Clint Guidry, a third-generation shrimper based in Lafitte, La., said he has felt the effect. It wasn't economical to fish farther offshore, past the Dead Zone, so in 1997 he sold his 97-foot boat. Now he works closer to the coast, catching smaller shrimp from a 35-foot skiff.
Rota likened the situation to the Gulf oil and gas boom, in which pipelines and other equipment cutting through the coast allowed saltwater to destroy wetlands.
''We've been basically a sacrifice zone for the nation,'' Rota said.