Another dead-zone research cruise begins Monday

By JANET McCONNAUGHEY, Associated Press Writer — Houma Courier
Published: Saturday, July 25, 2009 at 2:41 p.m.

NEW ORLEANS — Almost as soon as scientists who just measured the "dead zone" off Louisiana’s coast get their gear off the research boat "Pelican," scientists from Texas A&M will be loading their gear onto it for a different look at the dead zone.


Oceanographer Steven DiMarco and his crew of chemists, biologists, geographers and other scientists is trying to pry out details about processes that create a sea bottom area where there is too little oxygen for anything to live.


Nancy Rabalais of Louisiana Universities Marine Consortium, her husband, R. Eugene Turner of Louisiana State University and other Louisiana scientists worked out the broad picture some time ago.


Hypoxia occurs when algae blooms, fed by nitrates and phosphates in the water, die and fall to the bottom at the same time that winds still so that fresh water coming out of the rivers doesn’t get mixed into the denser salt water below it. Microbes feeding on the dead algae use up oxygen from the bottom up.


The A&M scientists are looking at more detailed workings. "I’m really interested in what is the combination of the currents and the mixing and the fresh water capping of that system. Where is that fresh water moving to? What is that variability? And relate that to the bottom dissolved oxygen," DiMarco said.


Research by his group has found that a dead zone in eastern Texas wasn’t — as had been thought — part of Louisiana’s, DiMarco said. "We did some isotope measurement of oxygen in the water, and identified that as coming directly from the Brazos River," he said.


Rabalais’ group, which found that the area was less than half the size predicted this year and one of the smallest ever, is scheduled to arrive in Cocodrie on Sunday.


DiMarco said, "The system is incredibly variable," with very little way to predict the dead zone’s size, "given that the physics of that system change daily to weekly," he said.  And, he said, "If there’s only one cruise that goes out every year to measure it, you’re not going to get a full representation of what the system is looking like."


On Monday, Rabalais and other researchers are to discuss the hypoxic problem in a telephone news conference with Jane Lubchenco, head of the National Oceanic and Atmospheric Administration.


While that’s going on, DiMarco and his group will be getting their gear onto the Pelican.

"We mobilize all day Monday, then leave as soon as we’re ready to go," he said.