BP Oil Spill: Undersea Plumes Nowhere to Be Found as Tests Show Seafood to Be Safe
On day 102 of the BP oil spill in the Gulf of Mexico, the oil is getting harder and harder to find, both on the ocean's surface and in the depths below.
For months, scientists monitored huge plumes of oil and dispersant deep beneath the waves. But now, they say, the plumes are nowhere to be found.
Watch "World News" for the latest on the Gulf oil spill tonight on ABC.
In the two weeks since the leaking well was capped, government and independent scientists have done extensive testing in the deep sea, and the results were not what they expected.
"We're finding hydrocarbons around the well, but as we move away from the well, they move to almost background traces in the water column," National Incident Cmdr. Adm. Thad Allen told ABC News.
Bacteria Have Consumed Oil Plumes, Scientists Say
Where could the undersea oil have gone? Today, many scientists across the Gulf Coast pointed to the same explanation -- deep sea bacteria called psychrophiles that have consumed the oil faster than anyone expected. The bacteria occur naturally in the waters of the Gulf, and when there's more oil present, they multiply to eat it.
"When a large amount of oil comes into the environment, then they quickly muster, if you will, and they can sometimes grow to 1,000-fold," said Jay Grimes, a professor of microbiology at the University of Southern Mississippi.
"They've been there for millions of years because of the fact that, for millions of years, we've had a large amount of natural oil seeping into the floor of the ocean," Grimes added.
Bacteria decompose the oil with a half-life of seven to 30 days, meaning that in that time period half of a plume could be consumed. In the following seven to 30 days, half of the leftover oil is eaten, and so on until all that's left is asphaltines, which form the basis of tar balls.
One of Grimes' students has been searching for oil on a research vessel for the last three days, finding no evidence of deep sea plumes.
No Oil Found in Seafood Samples
Scientists also are unable to find oil in Gulf seafood. In Louisiana state tests of more than 15,000 animals, not a single sample has been found to have elevated levels of oil contamination.
"We're not finding very much at all," said John Reuther, an analytical chemist for a lab that has been testing Louisiana seafood since the disaster began.
Acting on the positive evidence, Louisiana expects to reopen almost all of state fisheries in the next two weeks, according to Randy Pausina, assistant secretary of fisheries for the state's Department of Wildlife and Fisheries.
Only a few areas directly hit by oil will remain closed, as well as some areas where boom could interfere with fishing.
Problems Seen in Gulf's Tiniest Creatures?
Still, the good news doesn't mean that all is well in the ocean.
Scientists worry about the Gulf's tiniest creatures, like tiny blue crab larvae. Under the microscope, scientists are observing miniscule orange drops on the larvae that never have been seen before. Scientists worry that the drops are dispersed oil from the spill.
The frustrating truth is that it may take years to know the real effect of the spill on the Gulf ecosystem.
"We don't know enough right now to say if there's been large effects or not," said Dr. Erin Grey of Tulane University.
ABC News' Brian Hartman and Bradley Blackburn contributed to this report.
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Worry Underwater: Oxygen Levels Drop as Oil Continues to Flow
Evidence of marine biologists' doomsday scenario thrashes in the Gulf waters as sharks crowd into shallow waters.
Marine biologists say the sea animals flee the spill zone the way others would flee a forest fire. With thousands of gallons of oil contaminating their natural habitats, marine creatures press into oil-free waters.
"Their habitat is shrinking, tens of thousands of square miles are affected, and animals moving away from them," said Mobi Salangi, director of the Institute for Marine Mammal Studies. "There are changes in food, the food they eat and their prey."
Plumes of dense oil in shallow waters, up to 50 feet below the surface, have sucked up oxygen. Tests by the Dauphin Island Sea Lab usually show oxygen levels in the shallow waters at nearly eight parts per million. They're now down to two parts per million -- four times lower than normal.
Sharks, crabs, sting rays, birds and dolphins are all crowding piers, from Panama Beach, Florida, to the coasts of Louisiana.
Feeding frenzies are common in the Gulf, but the sharks jostling the Alabama coast are now much larger and in much greater numbers.
Biologists told ABC News that the entire food chain had been disrupted -- partly from the mass of oil and partly because the oil has sapped the water of oxygen.
"What we're really witnessing may be a shift in the whole ecosystem feeding structure, the food web," said Bob Shipp, director of marine biology at the University of Southern Alabama. "It also may be altered permanently -- as we've seen in other parts of the world where these things happen."
The oil spill has disturbed plant life too. Algae cannot survive if there isn't enough oxygen in the water, and a loss of algae could damage the ecosystem and the fisheries that rely on marine life.
Scientists said the oil may also cause the sea creatures' chemo receptors -- which function as built-in GPS systems to detect carbon dioxide levels -- to go on the fritz.
Deepwater Oil Plumes Also Affect Oxygen Levels
Samantha Joye, a marine scientist at the University of Georgia, told The Associated Press that the underwater oil plumes have reduced oxygen in the waters, but that it would take months for the oxygen to reach levels harmful to fish and animals, unlike in shallow waters, where oxygen levels have decreased at higher rates.
Joye said oxygen concentrations have dropped about 2 percent every day in the deepwater oil plumes, thousands of feet underwater.
Methane, which is also leaking from the Deepwater Horizon, poses another threat to underwater wildlife, as it attracts microbes that consume oxygen, and scientists said that if methane and microbe levels rise too much, they could create zones of so little oxygen that hardly anything could survive.