By David A. Fahrenthold
Washington Post Staff Writer
Monday, July 5, 2010; A04
How dead is the Gulf of Mexico?
It is perhaps the most important question of the BP oil spill -- but scientists don't appear close to answering it despite a historically vast effort.
In the 2 1/2 months since the spill began, the gulf has been examined by an armada of researchers -- from federal agencies, universities and nonprofit groups. They have brought back vivid snapshots of a sea under stress: sharks and other deep-water fish suddenly appearing near shore, oil-soaked marshes turning deathly brown, clouds of oil swirling in deep water.
But, with key gaps remaining in their data, there is wide disagreement about the big picture. Some researchers have concluded that the gulf is being spared an ecological disaster. Others think ecosystems that were already in trouble before the spill are now being pushed toward a brink.
"The distribution of the oil, it's bigger and uglier than we had hoped," said Roger Helm, a U.S. Fish and Wildlife Service official and the lead scientist studying the spill for the Interior Department. "The possibility of having significant changes in the food chain, over some period of time, is very real. The possibility of marshes disappearing . . . is very real."
Helm said that his prognosis for the spill had worsened in the past week -- as the amount of oily shoreline increased from Louisiana to Florida, despite cleanup efforts. "This just outstrips everybody's capability" to clean it up, he said.
This research has mainly occurred in the background, as public attention has focused on the "open-heart surgery" at BP's leaking wellhead.
The patient is a 600,000-square-mile sea, which contains swirling currents, sun-baked salt marshes and dark, cold canyons patrolled by sperm whales. Complicating matters is that even before the spill began in late April, the patient was already sick.
In recent years, Louisiana has been losing a football field's worth of its fertile marshes to erosion every 38 minutes. In the gulf itself, pollutants coming from the Mississippi's vast watershed helped feed a low-oxygen "dead zone" bigger than the entire Chesapeake Bay. Measuring the spill's damage, then, requires distinguishing it from the damage done by these other man-made problems.
So far, even the simplest-sounding attempts to measure the spill's impact have turned out to be complex.
The official toll of dead birds is about 1,200, a fraction of the 35,000 discovered after the Exxon Valdez spill in 1989. But this, too, has been called into question. Officials can only count the birds they can find, and many think a number of oily birds have sought refuge in the marshes.
"It's an instinctive response: They're hiding from predators while they recover," said Kerry St. Pé, head of a government program that oversees Louisiana's Barataria Bay marshes. "They plan to recover, of course, and they don't. They just die."
Other scientists have focused on more subjective measures of the gulf's health -- not counting the dead, but studying the behavior of wildlife, the movements of oil and the state of larger ecosystems. For them, solid answers are even more elusive.
For example: Is the oil killing off Louisiana's coastal marshes? state officials have said in interviews that they've seen it coating the grasses and mangroves that hold the region's land in place.
"The marsh grasses, the canes, the mangrove are dying. They're stressed and dying now," said Robert Barham, secretary of the state's Department of Wildlife and Fisheries. "There's very visible evidence that the ecosystem is changed."
But Paul Kemp of the National Audubon Society said he flew over the same area and saw a different picture: The oil's damage was relatively small, at least in comparison with the marsh's existing problems.
"Here, we have a patient that's dying of cancer, you know, and now they have a sunburn, too," Kemp said. "What will kill coastal Louisiana is not this oil spill. What will kill coastal Louisiana is what was killing it before this oil spill," including erosion and river-control projects that have reduced the buildup of new land.
Further offshore, federal scientists and university researchers have disagreed about the existence of "plumes" or "clouds" of dissolved or submerged oil. Several educators have reported finding underwater oil dozens of miles from the spill: Sometimes, they reported it was so well dissolved that the water appeared clear. In other situations, they found what they thought to be oil globs the size of golf balls.
Just around the leaking BP wellhead, a Texas A&M University scientist reported finding pockets of water with very low dissolved oxygen. That might be a sign that bacteria were consuming oil from the spill -- but, in the process, the water became suffocating for other sea life.
The government has presented a very different picture of the deep gulf.
An official at the National Oceanic and Atmospheric Administration said his agency had found evidence of significant submerged oil -- 1 to 2 parts per million -- from the BP spill only within six miles of the well. In addition, the U.S. Environmental Protection Agency has said it has not seen "large scale" problems with low dissolved oxygen around the submerged oil in the gulf.
Doug Inkley, senior scientist at the National Wildlife Federation, said he did not think the government had studied these areas well enough yet.
"I've been frustrated with the calm reassurances that we've been receiving, because . . . I don't know what they're based on," Inkley said. In particular, he said he was worried that submerged oil might kill deep-water coral colonies that had grown over the course of centuries.
"Think of going and cutting down a giant Sequoia tree. . . . If these corals are killed, then those areas will be vacant for some time," Inkley said.
For those who study fish -- literally, moving targets -- the data so far are a confusing hash of anecdotes and sightings.
In Sarasota, Fla., scientists found an 11-foot tiger shark, normally an open-water fish, drifting near the surf. That, plus sightings of whale sharks and other creatures outside their normal environmental range, raised concerns that oily water or low oxygen in the central gulf might be driving fish toward land.
"It would be like, to these fish, almost like an island, a huge island rising up in the middle of the gulf," said Bob Hueter of the Mote Marine Laboratory in Sarasota. Seeing this and other strange patterns in fish, Hueter said, "I just, all of a sudden, just felt this impending sense of doom, that the place that I loved was going to be changed in a very dramatic way."
Federal scientists, however, say that they've seen evidence that even plankton -- some of the smallest, most sensitive creatures in the gulf -- are living in the area around the leaking well.
"Right now," said John Valentine, who studies the gulf from the Dauphin Island Sea Lab in Alabama, "we should be more impressed by what we don't know than what we do know."