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.