Steven DiMarco, associate professor in the Department of Oceanography and leader of the team, found that some areas that were previously hypoxic - a technical term for extremely low dissolved oxygen concentrations in water - had broken up and appeared to pose little threat to marine life, while in other areas the hypoxia appeared to have moved further off shore.
Hypoxia can result in fish kills and can adversely affect many types of marine life where it is present. The dead zone area encompassed more than 6,000 square miles this year.
"We found that the hypoxia had moved offshore from shallow waters to much deeper waters in the Gulf," DiMarco explains. "In other words, much of the dead zone had broken up, and this very much surprised us."
DiMarco believes there are two reasons why the region affected by hypoxia broke up and changed location.
"Strong coastal currents can develop and breakup the stratification that causes hypoxia," he says. "Another is offshore circulation features, such as eddies, that intrude onto the continental shelf. We think this could break down the hypoxia in the area as well."
The NOAA (National Oceanic and Atmospheric Administration) study, conducted from Texas A&M's research ship R/V Gyre, stretched from an area near Southwest Pass, La., to the Calcasieu Ship Channel near the Texas-Louisiana border.
There are numerous theories as to the cause of the dead zone. Many scientists believe it is caused by fertilizer runoff from the Mississippi River, while other theories point to more complicated and interrelated factor
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Contact: Keith Randall
kr@univrel.tamu.edu
979-845-4644
Texas A&M University
30-Sep-2004