Previous dead zones have been recorded off the Louisiana coast for years, near the Mississippi delta region, and a dead zone there has been measured at more than 7,900 square miles, or about the size of Delaware and Connecticut combined.
DiMarco was the first to discover a Texas-created dead zone area off the Texas coast last summer, a result of unusually heavy rains that poured water into the Brazos River. Where the water emptied into the Gulf off the Texas coast, it created the first proven dead zone area that originated from Texas rivers.
The new results show that another fingerprint from Texas is the cause of dead zones since 1985, he adds.
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. Thats similar to what happens to marine organisms along the Texas coast.
He notes the dead zone is believed to extend about 20 miles off the coast in these areas, but could be larger. Thats 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 Texas coast in July for more samples and to test the concentration levels of hypoxia from several sites.
|Contact: Keith Randall|
Texas A&M University