Dead zone threatens Miss., too Oxygen-poor water off La. may spread this way, killing marine life

A big problem in Louisiana may be drifting into Mississippi waters. It’s invisible, and Mississippi coastal experts say they may not have the manpower to detect it.
The dead zone, an area of oxygen-depleted water off the Louisiana coast that lacks marine life, could reach its largest size since 1985 – roughly that of Massachusetts – this summer. The growth could push it into Mississippi’s coastal waters.
"We have a fear it could come in here and wipe out our fisheries," said Louis Skrmetta, captain of Ship Island Excursions in Gulfport and a member of the Gulf Restoration Network’s board of directors.
The dead zone is expected to be more than 10,000 square miles this summer, according to a study released last week by Louisiana State University and the Louisiana Universities Marine Consortium, or LUMCON. It has averaged about 6,000 square miles since 1990.
The dead zone forms as substances from farms, such as nitrogen and phosphorous, travel down the Mississippi River or one of its tributaries and into the Gulf.
These fertilizers, which help plants grow on land, cause algae to grow in the water. The algae deplete the oxygen, causing a dead zone at the bottom of the water.
Dead zones disperse what marine life can swim away and kill what can’t.
This year’s massive floods will bring a heavier load of fertilizer into the Gulf.
"We’re fooling around with a third of the U.S. fisheries," said R. Eugene Turner, an LSU coastal ecology professor.
"We’ve seen it change in places in Europe, and it’s been a disaster."
Dead zones also cause red tides, which could kill lots of fish and hurt tourism on the Coast, which attracts about 1 million people a year.
"People visit Ship Island because of its beautiful, clean water," Skrmetta said. "A red tide could come in here, and it would be a massive fish kill and hurt tourism."
Pascagoula is the Gulf’s third largest port for poundage of fish shipped out, 178 million pounds a year.
"Off the coast of Louisiana, there’s a huge area where you can’t catch fish," said Nancy Rabalais, LUMCON executive director. "The same thing would happen off Mississippi. They have lots of reefs, and there are die-offs around these artificial reefs."
If no hurricane or other tropical activity disrupts the dead zone and aerates it, it could grow by one-fifth from last year. Researchers have been studying it since the 1970s.
"We lack enough information to tell whether it’s a problem (in Mississippi) and if it’s getting more severe," said Steven Lohrenz, chairman of the University of Southern Mississippi’s Department of Marine Science.
Lohrenz said Mississippi has had small dead zones before and that he has concerns about their growth.
Lohrenz said USM has done several cruises to examine oxygen near the barrier islands off the Mississippi shore. In past years, the research has shown low levels, he said.
He said continental shelf has two dead zones in the region – one near the barrier islands and one near the Mississippi River delta. The areas are not as serious as the dead zone in Louisiana.
"Whether we see something on the Gulf Coast or some kind of algal bloom is unknown," Lohrenz said. "We don’t understand shelf ecosystems enough (in Mississippi) to say why it’s occurring."
Rabalais said large amounts of river flow have led to dead zones off Mississippi because currents move the high water east of the delta.
Mississippi’s coast is not only threatened by a widening dead zone south of the river’s delta but by a possible diversion of water.
If the waters rise again in lower Louisiana, that state may open the Bonnet Carre Spillway, which would divert the Mississippi’s waters into Lake Pontchartrain, through the Rigolets and Lake Borgne and then into Mississippi’s coastal waters. The spillway, north of New Orleans, was used earlier this year to lower river levels.
But Rabalais said she does not expect the river to crest in Louisiana as it has in Midwest states during recent flooding there.
The EPA’s Mississippi River/Gulf of Mexico Watershed Nutrient Task Force recently released a plan calling on 31 states to better monitor nutrients released into the river and its tributaries. Last week, it announced its plan to award $4.2 million in grant money to people interested in adopting programs that would reduce nutrients. The grants target areas along the Mississippi and Ohio rivers.
The dead-zone forecast is based on nitrate levels in the Mississippi River in Baton Rouge. A follow-up forecast will be made in July.
"By that time, we should see that influence of all the freshwater in the Gulf," Rabalais said.
Turner said Midwest farming has been a major factor in the dead zone’s growth.
"The intensive farming of more land, including crops used for biofuels, has definitely contributed to this high nitrogen loading rate," Turner said.
It grows as the Mississippi and Atchafalaya rivers dump nutrients into the waters. Nutrients that lead to dead-zone growth include runoff from developed land, atmospheric deposition (particles from air that get deposited into water), soil erosion, agricultural fertilizers, sewage and industrial discharge.
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