Dead Zones in the Gulf?

The challenge to uncover and report the 'Truth' about what's going on in the Gulf of Mexico is apparently going to be an ongoing battle. Concerns have already been raised about what the public is being told regarding the levels of oil in fish and other aquatic species. Now a dispute over where and by how much oxygen is being depleted has surfaced. (GW)

Scientist Says Oxygen-Depletion Problem in Gulf Is Real

By Jeffrey Ball
Wall Street Journal
July 14, 2010

A university researcher questioned the significance of government data that suggest oxygen levels in the Gulf of Mexico haven't dropped enough to be of serious concern.

Samantha Joye, an oceanographer at the University of Georgia who is studying the oil spill's potential effects on Gulf marine life, said water samples that she and colleagues have taken show a more worrisome drop in oxygen levels than was reported recently by a separate group of federal researchers aboard a different ship.

Workers collect tar balls Saturday along Crystal Beach in Texas. Officials say they are still testing whether the tar balls resulted from the oil spill.

The federal scientists were testing an area closer to the leaking wellhead, where the oil was fresher, Ms. Joye said. Oil farther away, which had been in the water longer, was more likely to have attracted oil-eating bacteria that reduce oxygen levels, she said.

"It certainly isn't safe to conclude there is no oxygen problem, based on oxygen measurements that are made close to the spill site," Ms. Joye said in a call Tuesday with reporters. Referring to the federal tests, she said: "I don't think that's a wise way to make conclusions about oxygen."

Federal officials reported last month that, based on one research trip, oxygen levels didn't appear to have fallen to dangerous levels, though the government urged further monitoring.

The federal government plans to release additional data about oxygen levels Thursday, based on testing of a broader area of the Gulf, said Steve Murawski, chief science adviser for the fisheries unit of the National Oceanic and Atmospheric Administration.

"We've done a lot more work," he said. He declined to discuss what the additional data showed, saying the government was awaiting completion of peer review.

Ms. Joye and her colleagues found that underwater oxygen levels in certain areas they tested had dropped several times as much as the federal researchers found in their samples, she said in an interview Tuesday. The declines were most pronounced near where the researchers detected a plume of oil and methane, she said.

Both groups of researchers say more testing is needed to determine how much oil and methane from the well are underwater and how severely they are affecting oxygen levels.

The tests are complicated by the fact that, for years, a swath of the Gulf coast has experienced a summertime plunge in oxygen levels, becoming what some researchers call a seasonal "dead zone." Scientists attribute that to nutrients from the Mississippi River entering the Gulf. Organisms in the warm summer water consume the nutrients, using oxygen in the process, scientists say.

The university and federal researchers "both could be right," said Robert Gagosian, president of Ocean Leadership, a Washington-based nonprofit consortium of oceanographic research institutions. "The only way you're going to find out is to have long-term studies and sample in a lot of different locations."

On June 8, Ms. Joye reported that, during a two-week Gulf research voyage, she and colleagues had found a large submerged plume of oil and methane. The oxygen levels dropped most significantly about nine miles from the wellhead, she said. Oil spills can reduce underwater oxygen levels in large part because natural bacteria in the water begin digesting the oil, and the bacteria consume oxygen in the process.

On June 23, federal officials reported that a separate research trip by a government ship in May had found that levels of dissolved oxygen in the Gulf "remained above immediate levels of concern, although there is a need to monitor dissolved oxygen levels over time." That conclusion was based on tests largely taken within a couple of miles of the wellhead.

BP robots attached a new, tighter-fitting cap on top of the gushing Gulf of Mexico oil leak, raising hopes that the crude could be kept from polluting the water for the first time in nearly 3 months. Video courtesy Fox News.

The federal report found "no evidence of large-scale changes" in underwater levels of dissolved oxygen. But it noted its conclusion was based on a research trip that ended May 25—and that large amounts of oil continuing to pour into the Gulf since then might have depleted oxygen levels further.

The data to be released by the government in coming days cover research conducted through the third week of June, NOAA's Mr. Murawski said.