Most Oil Still on Sea Floor - UBM [David Eells]

St. Petersburg, Florida (CNN) -- Oil from the Deepwater Horizon spill may have settled to the bottom of the Gulf of Mexico further east than previously suspected and at levels toxic to marine life, researchers reported Monday.

Initial findings from a new survey of the Gulf conclude that dispersants may have sent the oil to the ocean floor, where it has turned up at the bottom of an undersea canyon within 40 miles of the Florida Panhandle. Plankton and other organisms showed a "strong toxic response" to the crude, according to researchers from the University of South Florida.

"The dispersant is moving the oil down out of the surface and into the deeper waters, where it can affect phytoplankton and other marine life", said John Paul, a marine microbiologist at USF.

Results of the latest survey are scheduled to be released Tuesday, but CNN obtained a summary of the initial conclusions Monday night. Tests conducted offshore indicate the oil matches the 205-million-gallon Deepwater Horizon spill, which has been temporarily capped for a month, the summary states.

Some of it has spread into the DeSoto Canyon, a channel on the ocean floor east of the ruptured well. That canyon comprises part of the spawning grounds for much of the Gulf's commercial fish. "To date, this is the easternmost location for the occurrence of subsurface oils", the report states.

The oil is not "draping" across the bottom, but is spread out in "small, unevenly distributed droplets", the report states. USF chemical oceanographer David Hollander said that when an ultraviolet light used to detect oil was turned onto the sea floor, "All of a sudden, it turns out to be a constellation of little dots".

And the oil could well up onto the continental shelf and resurface later, Paul said. Or it could be eaten by fish and other animals and accumulate in the food chain, Hollander said.

"It's in such small droplets that you can see it -- you can filter it and see it", he said. "But if you look at it, it's transparent, and small larval fish see these droplets as food so they're ingesting pure oil".

The Environmental Protection Agency has previously reported some oil turning up in the sediment at the bottom of the Gulf, but has not determined whether it came from the Deepwater Horizon spill that erupted in April or whether it was already present. And on August 4, the head of the National Oceanographic and Atmospheric Administration warned that oil could persist in the water even though the well has been temporarily capped.

The oil company BP used more than 1.8 million gallons of chemical dispersants on the Deepwater Horizon spill between its eruption in late April and the time the well was capped in mid-July. BP says the chemicals allowed the oil to be broken up into droplets small enough that microbes can digest it, and the Environmental Protection Agency has said the dispersants were no more toxic than the oil itself.

Critics warned the full effect of the dispersants on the food chain was not known and that their use in deep water effectively concealed the full extent of the spill.

NOAA spokeswoman Mary Jane Schramm said on Monday that she had not seen the latest study and couldn't comment on it. BP spokesman John Curry, meanwhile, said the company wants "to know everything everyone wants to know".

The company is responsible for capping, cleaning up and compensating victims of the oil spill, and it has committed to spending $500 million to research the spill's impact over the next 10 years. The latest study will "add another piece to the puzzle", Curry said.

"There will be others that'll want to look at this study and want to look at doing some additional research", he said. "There's been extensive testing up to this point, and I'm sure there will be much more going forward".

Scientists Say as Much as 79% of Oil Remains in Gulf of Mexico
By Kim Chipman - Aug 17, 2010 6:04 PM ET

A group of scientists says as much as 79 percent of BP Plc's leaked oil remains in the Gulf of Mexico, challenging an Obama administration assessment that the crude is largely gone or rapidly disappearing.

Most of the oil that leaked from BP's Macondo well from April 20 to July 15 is still beneath the water's surface, five scientists including Samantha Joye, a professor of marine sciences at the University of Georgia in Athens, concluded in a memo made public yesterday. The researchers say they drew upon the U.S. government's study while reaching different conclusions.

The Obama administration's Aug. 4 report indicated that almost three-fourths of the crude that leaked has disappeared or soon will be eaten by bacteria. Jane Lubchenco, administrator of the National Oceanic and Atmospheric Administration, has said at least half of the oil released is now "completely gone".

Chemist Dana Wetzel said the administration's conclusion felt like the "closing credits of a movie".

"It's like they were saying 'the end'", Wetzel, program manager at Mote Marine Laboratory in Sarasota, Florida, said in an interview last week. "I'd say we have just gotten through setting up the plot".

The government and independent scientists involved in the administration's report "have been clear that oil and its remnants left in the water represent a potential threat, which is why we continue to rigorously monitor, test and access short- and long-term ramifications", Justin Kenney, a NOAA spokesman, said today in a statement. He also challenged the calculations used by the administration critics.

Oil Still There

Charles Hopkinson, a University of Georgia marine scientist and one of the five researchers, said plumes of oil dispersed underwater remain a danger.

"One major misconception is that oil that has dissolved into water is gone and, therefore, harmless", he said in a statement released yesterday. "The oil is still out there, and it will likely take years to completely degrade. We are still far from a complete understanding of what its impacts are".

Other scientists agree with the government that the oil has largely dissipated.

"I don't think it's still lurking out there", Edward Overton, an environmental chemist and professor emeritus at Louisiana State University, said in an interview last week.

'Incredible' Resiliency

"The Gulf is incredible in its resiliency and ability to clean itself up", said Overton, who served as a technical reviewer for the administration's report. "I think we are going to be flabbergasted by the little amount of damage that has been caused by this spill".

The leak began after the Deepwater Horizon drilling rig leased by London-based BP exploded off the coast of Louisiana, killing 11 workers and oiling as much as 650 miles of coastline.

The scientists who said that as much as 79 percent of the oil is still in the Gulf of Mexico said their estimates don't include oil known to have washed into coastal wetlands because such crude is too difficult to measure, according to the memo, dated Aug. 11 and written by Hopkinson.

The scientists also said they reached their estimates by assuming about 4.1 million barrels of oil spewed into the Gulf of Mexico, 800,000 barrels fewer than reported by the government, because the researchers didn't include oil that was piped directly from the well to surface ships.

"The report neglects the oil contained directly from the wellhead, which shifts the baseline numbers so that direct comparison" can't be made with the administration's calculations, Kenney of NOAA said in the statement.

Obama's Florida Visit

President Barack Obama and administration officials have emphasized positive news about the Gulf region since the flow of oil from the biggest U.S. spill was halted.

Obama and his family traveled to Florida's Gulf coast on Aug. 14 in a bid to provide the region with an economic boost. The president, who took a swim with daughter Sasha, said beaches along the coast are clean and open for business and the seafood is safe. Obama also said he won't be satisfied until the environment along the Gulf has been restored.

"Mother Nature did some nice work for us in terms of evaporation and dissolution of the oil in the water", Carol Browner, Obama's top environmental adviser, said earlier this month.

Florida Scientists

Scientists from the University of South Florida in St. Petersburg said in a separate study that they have seen evidence oil observed underwater has become poisonous to marine life.

The oil was found in the "critical" DeSoto Canyon that supports spawning grounds for commercially important fish species on the West Florida Shelf, according to an e-mailed statement from the school today.

Robert Weisberg, a scientist at the university, said today that it's not yet known how the oil remaining in the Gulf of Mexico may affect the ecosystem.

"There is subsurface oil", he said in an interview. "I don't care what anyone says. But the truth is we really don't know yet about the concentration levels".

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