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Great Lakes Article:

Death in the dead zone
By Robert Montgomery
BASS Times
05/14/03

Scientists believe that the exotic zebra mussel is a contributing factor to the demise of Lake Erie.


Conflicts over a natural resource aren't always over its use and allocation. Sometimes they're about the casualties sustained due to the abuse we, as a society, inflict on the resource.

One "water war" that continues to rage involves who's responsible for the nitrogen pollution that feeds the "dead zone" in the Gulf of Mexico each summer and fall. From the mouth of the Mississippi River, this zone of oxygen-depleted water spreads out for thousands of square miles to the south and west. No fish or other forms of aquatic life can exist in the zone. Those that can't move away fast enough often die.

The dead zone occurs because the nutrient overload feeds massive algae blooms. The blooms eventually die and decay, robbing the water of life-sustaining oxygen.

According to the U.S. Environmental Protection Agency, "the hypoxic zone centers squarely in the middle of one of the most important fisheries in the United States, an area that produces 40 percent of the country's commercial fish and shellfish. In Louisiana, commercial fishing supports 90,000 jobs and has an economic impact of $1.5 billion .

"To compensate for ecological changes wrought by hypoxia, Gulf fishing boats are now moving farther out to sea to reach the shrinking fishery, spending more for fuel, supplies and wages. Others drop their nets closer to shore, causing localized overfishing of the nearshore areas."

Most researchers believe that runoff from agricultural lands, especially above the confluence of the Mississippi and Ohio rivers, is to blame for the nitrogen that feeds the dead zone.

Farmers disagree, saying that no proof exists as to the cause.

The U.S. Geological Survey (USGS) and other groups, however, maintain that perhaps as much as 60 percent of the nutrient load comes from fertilizer, plant debris and minerals from soil fodder. About 15 percent is linked to animal manure, much of it from factory farms.

Iowa and Illinois are believed to contribute about 35 percent of the nitrogen load.

"I'm sure overfertilized golf courses in some places would contribute, as would the fertilizer people put on urban lawns," said Donald Goolsby, a retired USGS hydrologist.

"It all contributes but if you look at the real hot spots for this nitrogen discharge, they're not high-population areas. They're not places with huge wastewater plants of industrial emissions. They're croplands."

As additional evidence that farming practices are damaging the fishing industry of the Gulf, researchers point to the Black Sea. It, too, was sickened by a dead zone for decades. Then farmers lost their state-issued fertilizer when the Soviet Union collapsed, and oxygen has returned to the water.

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