Researcher says Gulf dead zone bigger than ever

By MICHAEL GRACZYK, Associated Press Writer Wed Jul 23, 5:39 AM ET

HOUSTON - A "dead zone" in the Gulf of Mexico off the Texas-Louisiana coast this year is likely to be the biggest ever and last longer than ever before, with marine life affected for hundreds of miles, a scientist warned.

"It's definitely the worst we've seen in the last five years," said Steve DiMarco, a Texas A&M University professor of oceanography who for 16 years has studied the Gulf of Mexico dead zone, so named because the oxygen-depleted water can kill marine life.

The phenomenon is caused when salt water loses large amounts of oxygen, a condition known as hypoxia that is typically associated with an area off the Louisiana coast at the mouth of the Mississippi River. The fresh water and salt water don't mix well, keeping oxygen from filtering through to the sea bottom, which causes problems for fish, shrimp, crabs and clams.