10:00 PM CDT on Thursday, October 7, 2004

By Dave Fehling / 11 News

KHOU-TV

Scientists crisscrossed the Gulf to plot the Dead Zone.

There is new information about a mystery in the Gulf of Mexico that scientists call the "Dead Zone".

It's a huge area where every summer, sea-life disappears just off the coast. Because of the Zone, this past summer was filled with unusual occurrences on the Texas Gulf Coast.

Shark attacks, otherwise rare, happened three times in a few weeks. Killer whales, unheard of in this part of the Gulf, appeared off the Corpus Christi coast.

Some wondered if the Gulf was out of whack because of the Dead Zone.

Oceanographer Steven DiMarco may have found some answers.

Leaving from Galveston aboard a Texas A&M research vessel, DiMarco and other scientists crisscrossed the Gulf to plot the Dead Zone. The result is a computer model that shows the amount of oxygen in the water, represented by colors.

In early summer, there is a lot of it and the color is orange. Starting in July along the Louisiana coast, the oxygen deep down in the Gulf diminishes. It is represented by a blue area as big as New Jersey.

The suspected cause is fertilizer and animal waste runoff from farms. That causes algae to go wild, eating up the oxygen.

"During the '90s it got bigger. It did move closer to Texas and that got everybody's attention," says DiMarco.

Fish usually flee the low-oxygen Zone. That is why, when DiMarco's crew arrived in the area in August, they were perplexed by what they saw. "On our cruise, we saw the shrimpers in full force in that region," he says.

So the researchers began running hundreds of tests and surprisingly, they found the Dead Zone was virtually gone.

"In many spots it looked like it had dissipated almost completely and other places it had moved off shore," DiMarco says.

DiMarco says part of the reason for the change is the currents. Strong, coastal currents normally not seen until September came early this year, churning along the coast, breaking the Zone apart.

Then came a tropical storm and a couple hurricanes.

Active hurricane seasons may be good news when it comes to reducing the size of the Dead Zone, DiMarco says, because wind mixing is pretty much the enemy of the Dead Zone.

But just as the weather is unpredictable, there's no way to say how long the Dead Zone will last next summer, or if it will upset the big fish along the Texas Coast.

For now, DiMarco doubts it. "I would think that would have to be a stretch, to say that the shark attacks off Texas were related to the Dead Zone," he says.

Still, scientists say it is a problem that threatens sea life, and if left unchecked, may move closer to Texas.