Image: Blue heron
Dave Martin  /  AP
A blue heron snacks in the surf as oil cleanup crews make their morning patrol along the beach in Gulf Shores, Ala., on Wednesday.
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updated 6/16/2010 11:24:04 PM ET 2010-06-17T03:24:04

Dolphins and sharks are showing up in surprisingly shallow water just off the Florida coast. Mullets, crabs, rays and small fish congregate by the thousands off an Alabama pier. Birds covered in oil are crawling deep into marshes, never to be seen again.

Marine scientists studying the effects of the BP disaster are seeing some strange — and troubling — phenomena.

Fish and other wildlife are fleeing the oil out in the Gulf and clustering in cleaner waters along the coast. But that is not the hopeful sign it might appear to be, researchers say.

The animals' presence close to shore means their usual habitat is badly polluted, and the crowding could result in mass die-offs as fish run out of oxygen. Also, the animals could easily get devoured by predators.

"A parallel would be: Why are the wildlife running to the edge of a forest on fire? There will be a lot of fish, sharks, turtles trying to get out of this water they detect is not suitable," said Larry Crowder, a Duke University marine biologist.

The nearly two-month-old oil spill has created an environmental catastrophe unparalleled in U.S. history as tens of millions of gallons of have spewed into the Gulf of Mexico ecosystem. Scientists are seeing some unusual things as they try to understand the effects on thousands of species of marine life.

Day by day, scientists in boats tally up dead birds, sea turtles and other animals, but the toll is surprisingly small given the size of the disaster. The latest figures show that 783 birds, 353 turtles and 41 mammals have died — numbers that pale in comparison to what happened after the Exxon Valdez disaster in Alaska in 1989, when 250,000 birds and 2,800 otters are believed to have died.

Researchers say there are several reasons for the relatively small death toll: The vast nature of the spill means scientists are able to locate only a small fraction of the dead animals. Many will never be found after sinking to the bottom of the sea or getting scavenged by other marine life. And large numbers of birds are meeting their deaths deep in the Louisiana marshes where they seek refuge from the onslaught of oil.

"That is their understanding of how to protect themselves," said Doug Zimmer, spokesman for the U.S. Fish and Wildlife Service.

'Dead zone' periods
For nearly four hours Monday, a three-person crew with Greenpeace cruised past delicate islands and mangrove-dotted inlets in Barataria Bay off southern Louisiana. They saw dolphins by the dozen frolicking in the oily sheen and oil-tinged pelicans feeding their young. But they spotted no dead animals.

Video: BP launches second system to collect oil "I think part of the reason why we're not seeing more yet is that the impacts of this crisis are really just beginning," Greenpeace marine biologist John Hocevar said.

As for the fish, locals are seeing large schools hanging around piers where fishing has been banned; apparently the fish feel safer now that they are not being disturbed by fishermen.

Also, researchers believe fish are swimming closer to shore because the water is cleaner and more abundant in oxygen. Farther out in the Gulf, researchers say, the spill is not only tainting the water with oil but also depleting oxygen levels.

A similar scenario occurs during "dead zone" periods — the time during summer months when oxygen becomes so depleted that fish race toward shore in large numbers. Sometimes, so many fish gather close to the shoreline off Mobile that locals rush to the beach with tubs and nets to reap the harvest.

But this latest shore migration could prove deadly.

First, more oil could eventually wash ashore and overwhelm the fish. They could also become trapped between the slick and the beach, leading to increased competition for oxygen in the water and causing them to die as they run out of air.

"Their ability to avoid it may be limited in the long term, especially if in near-shore refuges they're crowding in close to shore, and oil continues to come in. At some point they'll get trapped," Crowder said. "It could lead to die-offs."

The fish could also fall victim to predators such as sharks and seabirds. Already there have been increased shark sightings in shallow waters along the Gulf Coast.

The counting of dead wildlife in the Gulf is more than an academic exercise; the deaths will help determine how much BP pays in damages.

Roger Helm, chief of the Fish and Wildlife Service's contaminants division, said the government expects a battle with BP over the extent of the damage and has every incentive to be scientifically credible.

"Both sides go to their own corner and interpret the data the way they want," Helm said. "This is a legal process, and if we can't get an agreement we'll end up in court."

Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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