Low-oxygen waters known as dead zones have appeared as regularly as the tides along the Texas coast, according to a new Texas A&M University study.

Although the first report of a dead zone off Texas came in 1979, researchers now believe the condition has repeated itself annually for at least 23 years and will likely continue – not unlike the lethal cycle that has threatened fish and shrimp in the waters off Louisiana for decades.

The cause is probably the slurry of soil that flows out of several rivers and into the Gulf of Mexico, but A&M oceanographer Steve DiMarco said more water-quality studies are needed.

DiMarco analyzed samples of Texas coastal waters and found that oxygen-starved dead zones have formed between the Louisiana border and Brownsville in all but one year since 1985, the oldest data available.

Evidence previously suggested sporadic dead zones. The new finding surprised DiMarco because the understanding had been that hypoxia, the scientific term for oxygen deficiency, was not persistent along the Texas coast.

Scientists still don’t know the impact of the Texas’ dead zone, which extends at least 20 miles offshore. DiMarco and industry officials said there are no reports of lower fishing catches or marine animal die-offs.

“We need to be out monitoring the water quality of coastal Texas in a systematic way so that if something really bad happens to the health of the coastal environment, we will at least have some data to have a shot at identifying a cause,” DiMarco said.

Mike Segall, owner of Reel Threel Saltwater Charters in Galveston and Freeport, said he has not found any oddities.

“You go offshore, and the fishing should be fine,” he said.

The size of the dead zones off Texas has fluctuated over the years, with the largest ever measured coming last year, when the National Oceanic and Atmospheric Administration detected a 1,750-square-mile area of low-oxygen water emanating from the mouth of the Brazos River near Freeport.

Full Story: http://www.chron.com/disp/story.mpl/metropolitan