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By Margaret Kriz, National Journal
© National Journal Group Inc.
Friday, Jan. 19, 2007

Many members of Congress are promoting ethanol as an environmentally friendly solution to the nation's dependence on foreign oil. But marine biologists worry that an ethanol boom will worsen the Gulf of Mexico's dead zone, the oxygen-starved region where marine life can't survive. "There's the possibility that biofuels, if they mean expansion of corn in the Midwest, could aggravate the problem," said Nancy Rabalais, a marine biologist and professor at the Louisiana Universities Marine Consortium.

The source of the gulf's hypoxia problem -- meaning a deficiency of oxygen -- lies in the nation's heartland. Most U.S. ethanol is made from Midwestern corn. If the region's farmers grow more corn, they'll use more fertilizer. Residue from the nitrogen-based fertilizer will be washed into streams that feed into the Mississippi River and flushed into the Gulf of Mexico.

Already, some 1.6 million metric tons of nitrogen flow into the gulf each year. The chemical boosts the summertime growth of algae and plankton, which eventually die and fall to the ocean floor. Bacteria feed on the decomposing plants and proliferate until they use up the oxygen on the bottom.

"The level of oxygen can decline to the point where it affects worms, clams, fish, and shrimp," said Robert Diaz, professor of marine science at the Virginia Institute of Marine Science at the College of William and Mary. "If it gets low enough and lasts long enough, animals that can't escape by crawling away or swimming die."

The Gulf of Mexico's dead zone, which is the size of New Jersey, is one of the world's most notorious hypoxic regions. And the number of U.S. dead zones is growing. U.S. coastal waters now contain at least 36 such zones, including areas in the Chesapeake Bay, off the Florida Keys, and in Long Island Sound, according to the 2003 Pew Oceans Commission report. That number doesn't include dead zones in Lake Erie and other bodies of fresh water. According to the 2004 U.S. Commission on Ocean Policy, "The severity and extent of nutrient pollution are expected to worsen in more than half of the nation's estuaries and coastal waters by 2020." Worldwide, the number of dead zones in oceans and seas has risen to 200, according to a United Nations report released last October.

"There's some thought that the frequency of these hypoxic areas is increasing in coastal waters. If it is, that certainly is cause for concern," said Steven Murawski, chief scientist for the National Marine Fisheries Service. Scientists need better monitoring data to assess the problem, he said. "Right now, [dead zones] generally come to our attention when we begin to see dead or dying animals."

Although some low-oxygen areas occur naturally, most are created by human activity, primarily the use of nitrogen-rich fertilizer on farms, runoff from large animal-feed lots, and wastewater discharges from treatment plants. Other contributors include runoff from America's cities and nitrates emitted by cars and electric power plants that burn fossil fuels.

Most dead zones in U.S. waters dissipate in the winter, when storms churn up the oceans and sea life returns to the area. "So far, nothing drastic has happened in the U.S. like it's happened in Europe or in Japan," where the dead zones have caused massive killings of fish, Diaz said.

But hypoxia is taking its toll. The U.S. oceans commission underscores that nutrient pollution kills fish, diminishes marine biodiversity, sickens people, and cuts into tourism. Last summer's Gulf of Mexico dead zone reduced the diversity of sea life in a 4,600 square mile area. Rabalais, who has been studying the problem since 1985, said that large fish don't come back to the area even when oxygen levels return to normal. Some scientists suggest that oxygen depletion has hurt the local shrimp populations.

The solution is to reduce the flood of nutrients into waterways. But federal regulators have had a hard time persuading farmers and city leaders to act. "This is diffuse-runoff pollution, and it's not regulated by the federal Clean Water Act," noted Benjamin Grumbles, EPA's assistant administrator for water. "It requires a concerted and collaborative effort" by federal, state, and local regulators, as well as by farmers and businesses, to prevent chemicals from washing into rivers and streams, he said.

Grumbles said that the federal government is tackling the problem, but Rabalais contends that she sees little improvement. "It's not getting worse, it's not getting better -- it's not being dealt with," she said. "That's what's happening." [an error occurred while processing this directive]

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