Gulf of Mexico "dead zone" to hit record size: NOAA
Tue Jul 15, 2008 9:19pm BST

By Chris Baltimore

HOUSTON (Reuters) - The Gulf of Mexico's "dead zone" -- a swath of 
algae-laden water with oxygen levels low enough to choke out 
marine life -- will likely reach record size this year, and the 
main culprits are rising ethanol use and massive Midwest flooding, 
scientists said on Tuesday.

The dead zone, which recurs each year off the Texas and Louisiana 
coasts, could stretch to more than 8,800 square miles

this year -- about the size of New Jersey -- compared with 6,662 
square miles in 2006 and nearly double the annual average since 
1990 of 4,800 square miles.

Scientists from the U.S. National Oceanic and Atmospheric 
Administration, Louisiana Universities Marine Consortium and 
Louisiana State University said the algae that lowers oxygen 
levels in the dead zone is being fed by farm use of fertilizers 
like nitrogen and phosphorus.

For fishermen who look to the Gulf of Mexico for crabs, shrimp, 
crawfish and other seafood, the growing dead zone means they must 
venture farther out into the gulf's waters to find their catch.

The record dead zone is due to soaring use of ethanol in U.S. 
motor gasoline supplies and by massive flooding in the Midwest 
earlier this year, scientists said.

"We're planting an awful lot of corn and soybeans," said Eugene 
Turner, a scientist at Louisiana State University. "It rinses off 
easily when there is a rain."

One-third of this year's U.S. corn crop, or 4 billion bushels, 
will go to make the alternate fuel ethanol, the U.S. government 
has projected, compared to 3 billion bushels of the 2007 crop.

The dead zone starts in Midwestern corn country when farmers 
fertilize their fields with nitrogen. The fertilizer run-off flows 
down the Mississippi River into the Gulf of Mexico, making algae 
bloom on the surface and cutting oxygen to creatures that live on 
the bottom.

Substances in this runoff include the nutrients nitrogen and 
phosphorus, which can stimulate the growth of algae. These algae 
settle and decay in the bottom waters of the Gulf, and the 
bacteria that decompose them gobble up oxygen faster than it can 
be replenished from the surface, which means lower levels of 
dissolved oxygen in the water.

U.S. scientists estimate that a record 83,000 tons of phosphorus 
seeped into the Gulf of Mexico from April through June, up to 85 
percent above normal seasonal levels.

"Excess nutrients from the Mississippi River watershed during the 
spring are the primary human-influenced factor behind the 
expansion of the dead zone," said Rob Magnien, director of the 
NOAA Center for Sponsored Coastal Ocean Research.

To reverse the pattern, U.S. farmers must plant more perennial 
crops that trap rainwater and keep it from running into the Gulf 
of Mexico, Turner said.

And eventually, scientists need to invent new breeds of perennial 
corn plants that can remain in the soil from one planting season 
to the next, avoiding the need to strip fields bare and leave them 
susceptible to flooding, he said.

(Reporting by Chris Baltimore, editing by Anthony Boadle)
Kyle J. Fricker
Chemical Engineering
University of Florida