Dead Zone Off Texas Coast Existed Since 1985Science Daily; April 1, 2008
Researchers at Texas A&M University have confirmed for the first time that a "dead zone" has existed off the Texas coast for at least the past 23 years and will likely remain there, causing potential harmful effects to marine life in the area.
Steve DiMarco, associate professor in Texas A&M’s College of Geosciences who has studied dead zones in the Gulf of Mexico for more than 15 years, believes the dead zone area off the Texas coast extends from the Texas-Louisiana border area to Brownsville. A dead zone occurs when there is hypoxia, or oxygen-depleted water.
Such low levels of oxygen are believed to be caused by pollution from farm fertilizers as they empty into rivers and eventually the Gulf, or by soil erosion or discharge from sewage treatment plants.
"Not all of the area from the Texas-Louisiana coast to
DiMarco recently presented his findings to the 2008 Ocean Sciences Meeting in
DiMarco examined water samples — provided by
Key areas sampled included
Water samples contained low oxygen levels, and in some years, alarmingly low, DiMarco said. When a dead zone occurs, marine life can be severely threatened, especially commercial fishing areas.
"The low oxygen levels since 1985 are frequent and persistent," he noted.
"It proves that a dead zone occurrence is not a one-year or two-year event, but it has happened just about every year for at least the last 23 years."
Previous dead zones have been recorded off the
DiMarco was the first to discover a Texas-created dead zone area off the
"The new results show that another ‘fingerprint’ from
"Hypoxia — oxygen-depleted water — occurs when the oxygen levels fall below 2 milligrams per liter, but we found numerous samples that were even one-half of that, meaning severe hypoxia has occurred."
DiMarco says a comparison would be that of standing on top of a mountain. "You know the air is going to be thin up there because of the altitude," he says. "The thin air has low oxygen levels making it uncomfortable and sometimes deadly to humans. That’s similar to what happens to marine organisms along the
He notes the dead zone is believed to extend about 20 miles off the coast in these areas, but could be larger. "That’s one big question we need to find out — how large an area is being affected by this dead zone"" he says.
DiMarco plans to go to the affected areas off the