Increasing corn production is expected to spawn an oxygen-starved "dead zone" in the Gulf of Mexico larger than anything seen in 23 years of recordkeeping - an 8,800-square-mile area, roughly the size of New Jersey - researchers said yesterday.
"It's had a disastrous effect on the fisheries for sure," said R. Eugene Turner, a research scientist with Louisiana State University.
An increase in corn production to manufacture ethanol-based fuels has jacked up the nutrients flowing down the Mississippi River to the gulf, where they deplete oxygen in the water, Turner said. More corn was planted in the United States last year - 94 million acres - than in any year since 1944, records show.
"We're planting an awful lot of corn and soybeans, and a lot of it isn't staying in the ground," he said yesterday at a news briefing sponsored by the National Oceanic and Atmospheric Administration, which funds his research.
It has not been proved that higher corn production is expanding the seasonal dead zone, an area so depleted of oxygen that fish cannot survive in it. But Turner said all the evidence points in that direction. Heavy rainfall and floods may also contribute, he said.
Meanwhile, runoff into the Chesapeake Bay this spring - from cornfields and a number of other sources - set the stage for algae blooms in a number of bay tributaries this summer, experts say.
Corn production increased by 10 percent in the bay watershed in the summer of 2007, but there is no way to know what effect that had on nitrogen levels flowing into the bay, said Beth McGee, senior water quality scientist for the Chesapeake Bay Foundation.
"We don't have the ability to see that level of detail," she said.
Dead zones are created when nitrogen from farms, lawn fertilizers and other sources flows into a waterway, stimulating the growth of algae that robs the water of oxygen as it decomposes. Algae blooms are a major concern in the bay and the Gulf of Mexico because they close beaches and make it impossible for fish, crabs and other aquatic life to survive.
"People may not think they care about dead zones, but they certainly care about rockfish and crabs and oysters, and they are all affected by dead zones," McGee said.
Dead zones occur periodically along the Atlantic Coast but the Gulf of Mexico is particularly susceptible to seasonal swaths because of farm runoff flowing in from the Mississippi and intense development in coastal flood plains, said Raghu Murtugudde, an expert on ocean microorganisms at the University of Maryland.
"They have destroyed their wetlands and they're paying a price for it," he said.
Each year in May or June, warm temperatures and still waters create a dead zone in the bay that begins near the Bay Bridge and expands south into Virginia, he said.
Based on pollution levels this spring in the Susquehanna River, William Dennison of the University of Maryland Center for Environmental Science estimated that this summer's depleted oxygen levels in the bay will be the sixth-worst since observations began in 1985.
Algae blooms have been reported in portions of the Potomac, Patuxent, Severn and Choptank rivers and in the mouth of the Miles River, Dennison said.
"The blooms are up and running as we speak," he said.