Tuesday, July 17, 2007

Gulf of Mexico "Dead Zone (Hypoxia) is growing

Along with so many of our environmental problems, this is one more that seems quite alarming and troubling, not only for the fishermen but also the big picture of our ecosystem. Since I didn't know about it, I'm assuming maybe some of you didn't either.

Gulf 'dead zone' is growing, researchers say
By Beth Gallaspy, The Enterprise

Researchers this week expect to find the largest "dead zone" of oxygen-depleted water in the Gulf of Mexico since they started measuring more than two decades ago.

Based on the amount of nitrogen flowing into the Gulf this spring from the Mississippi River, Nancy Rabalais predicts a dead zone covering about 8,543 square miles, larger than the state of Massachusetts.

Rabalais, executive director of the Louisiana Universities Marine Consortium, has studied the Gulf dead zone, known scientifically as the hypoxic zone, since 1985.

Hypoxia in the Gulf means an area with less than 2 milligrams per liter of dissolved oxygen.

High nitrogen levels are the major factor in formation of a swath of low-oxygen bottom waters nearly devoid of marine life off the coast of Louisiana, sometimes reaching into Texas. This year, nitrogen levels are above the long-term average and above last year's level, even though the amount of water discharged from the Mississippi River basin is below average, Rabalais saidThe reason for the excess nitrogen is anyone's guess.

"It could be related to agricultural practices. It could be a climatic factor in the watershed," Rabalais said. Increased corn plantings as an alternative fuel source could have some impact, but it is too early to track a trend there, she said.

Researchers will begin measuring dissolved oxygen levels and taking other samples at the mouth of the Mississippi River on Friday and work their way west, covering as large an area as possible in eight days.

If the size prediction holds true, this year's dead zone would top the previous high of 8,500 square miles in 2002. Last year, it measured 6,662 square miles.

A separate survey by the NOAA research vessel Oregon II last month found areas of hypoxia off the Texas coast about 40 miles south of High Island and hugging the coastline from the western end of Galveston Island to Matagorda Bay.

The trip was cut short by mechanical problems before NOAA was able to look at the area off Sabine Pass and the Louisiana coast. That leg is scheduled to resume next week after repairs are complete.

Nelson May, National Oceanic & Atmospheric Administration physical scientist, said the main focus of the NOAA survey is the fishery, but other environmental data such as low oxygen are collected as well.

The effect of the lack of oxygen on the fishery is dramatic, May said. Sometimes nets in a hypoxic zone will find fish, but often they come up empty, May said.

"On other occasions, you can see the crabs swimming on the surface, trying to get out of it," he said.

"You definitely don't see any shrimpers in the hypoxic zone. They've got that figured out," May said. Rabalais said it's hard to pinpoint the long-term impact of the low-oxygen areas on the fishery. In the short term, people still are catching fish and shrimp, but it has become more difficult.

"Livelihoods are being affected because they aren't going as much or they're having to go out farther," she said.

For some, it's no longer worth it, "especially compared to the cost of fuel and competition from cheap imports."

bgallaspy@beaumontenterprise.com(409) 880-0726


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