[Rhodes22-list] Expanding Dead Zone in the Gulf of Mexico

[Luis Guzman]

Interesting article from the Sierra Club:


Article published Jul 20, 2007

PHOTO BY NANCY RABALAIS / LOUISIANA
UNIVERSITIES MARINE CONSORTIUM
Nutrients flood into the Gulf of Mexico , consuming oxygen needed by marine life and turning the water color from oxygen-rich blue to brown. This May, flows in the Mississippi River contained 35 percent more nitrogen than in 2002. One theory for the increase is the 19 percent increase in corn plantings in the Midwest over 2006, to be used for ethanol.
More photos

HERALD-TRIBUNE ARCHIVE
In the Midwest , a rise in corn production to fuel the ethanol industry increased fertilizer use, and some say that is feeding a bigger dead zone. Scientists predict the zone will become as big as New Jersey .
Dead zone looks to be expanding in Gulf
By KATE SPINNER
kate.spinner at heraldtribune.com

A dead zone fueled by pollution in the northern Gulf of Mexico could reach record proportions this summer, creating thousands of lifeless miles off the coasts of Louisiana and Mississippi , the federal government reported this week.

Scientists predict that the dead zone in the northern Gulf will grow to roughly the size of New Jersey , fueled by nitrogen and phosphorus flowing out of the Mississippi River , possibly from an increase in the use of fertilizers to grow corn for ethanol.

Nutrient pollution is the most significant factor in predicting how big the Louisiana dead zone will grow, federal scientists said.

A dead zone is an expanse of deep oceanic water that becomes so oxygen-deprived that it cannot support sea life.

Nancy Rabalais, a scientist with the Louisiana Universities Marine Consortium, said the expanding lifelessness off the Louisiana coast was not surprising because pollution has increased.

"It's a worsening of a bad trend," she said "It shouldn't be that large. If human beings would do something, it wouldn't be."

Dead zones have been appearing off the coast of Mississippi and Louisiana each summer for at least two decades. They started out as smaller, sporadic events in the 1950s and grew larger and more frequent as pollution in the Gulf increased.

Dead zones grow in the summer because the combination of warmer temperatures and high nutrient loads from spring runoff fuel enormous algal blooms that sink to the bottom of the Gulf and die.

The decay process sucks oxygen from the water, suffocating any fish, shrimp or mollusks that become trapped in that area.

If predictions by the National Oceanic and Atmospheric Association come true, this year's 8,543-square-mile dead zone will be the largest since record-keeping began 22 years ago.

A smaller dead zone formed in 2002 after an unseasonably wet year flushed larger than normal amounts of polluted water into the Gulf.

This May, flows in the Mississippi were about 23 percent lower than in 2002, but the water contained 35 percent more nitrogen. That dynamic indicates something changed in the watershed, said David Whithall, a coastal ecologist with NOAA.

One of the most notable changes in the Midwest was the additional production of corn for ethanol. U.S. growers planted 19 percent more corn in 2007 than they did in 2006, according to USDA statistics.

It is too early to say with certainty that biofuel crops are the culprit behind the nutrient increase, but corn is hard on the land and requires more fertilizer than other crops, said Rabalais, of the Louisiana Universities Marine Consortium.

Rabalais said the dead zone would not be forming without excess nutrients. Nutrient pollution in the Gulf has tripled over the past 50 years, according to NOAA.

Using the same data that goes into predicting the dead zone size, Whithall said scientists are beginning to calculate how much nutrient reduction in the Gulf will be required to shrink the dead zone.

Similar prediction models could be used in other regions, but would have to be adapted for different conditions.

Waters off of Southwest Florida, for instance, do not come close to receiving the same volume of fresh water that flows from the Mississippi River .

The warmer climate, however, makes this region more susceptible to algal blooms, said Paul Carlson, a scientist at the Florida Fish and Wildlife Research Institute.

Here, the most recent dead zone formed after a widespread bloom of red tide algae killed a massive amount of fish in 2005. Those lifeless waters stretched from Pasco to Sarasota counties and covered an area larger than Delaware .

Scientists still debate whether red tide alga thrives in nutrient-rich water.

There is strong acknowledgment, however, that nutrient pollution is spawning the overabundance of seaweed, or drift alga, that has been washing up on area beaches.

The "sheer quantity" of seaweed tumbling around in local waters is a "cause for concern," said Merrie Beth Neely, another state researcher. She said it could trigger oxygen-depleted waters if it accumulates and decomposes in one place.

But she also said dead zones here are unlikely this year, due to drought conditions keeping runoff, and nutrient levels, low.

The problem in the northern Gulf is a wake-up call for local government to reduce pollution here, said Wayne Genthner, a Sarasota boat captain.

Genthner and the Sierra Club have been encouraging Sarasota County to pass laws that would limit the type and the quantity of fertilizer residents can put on their lawns.

"That dead zone up there is just another case in point that what you put on the land goes to the sea," Genthner said.

The Sarasota County Commission, under pressure from landscapers and the fertilizer industry, delayed a decision on new restrictions at its last meeting.

The county is expected to pass the laws next month. Charlotte and Manatee counties are just starting to discuss proposing similar rules.

 
Stuart DeCew
Red Tide Campaign
Sierra Club 
Sarasota Office 941-951-6084
St. Pete Office 727-824-8813 ext. 310
www.sierraclub.org
Explore, enjoy and protect the planet.


       
____________________________________________________________________________________
Be a better Heartthrob. Get better relationship answers from someone who knows. Yahoo! Answers - Check it out. 
http://answers.yahoo.com/dir/?link=list&sid=396545433