Scientists at the University of South Florida gathered the evidence of microscopic amounts of oil mixing into the soil of the canyon.
They also found poisoned plant plankton -- the vital base of the ocean food web -- which they blamed on a toxic brew of oil and dispersants.
Their work is preliminary, hasn't been reviewed by other scientists and requires more tests to confirm it is BP's oil they found.
It is based on a 10-day research cruise that ended late Monday night. Scientists who were not involved said they were uncomfortable drawing conclusions based on such a brief look.
But the USF experts' early findings are only the latest in a string of scientific reports that strongly question the government's sanguine views of the oil spill cleanup.that their analysis shows most of the BP oil the government said was gone from the Gulf of Mexico is still there.
The Georgia team say as much as 80 percent of the oil still lurks under the surface, and that it is a misinterpretation of data to claim that oil that is dissolved is actually gone. The report from University of Georgia and other scientists came from an analysis of federal estimates.
Earlier this month federal scientists said that only about a quarter of the oil remained and the rest was either removed, dissolved or dispersed.
"Where has all the oil gone? It hasn't gone anywhere. It still lurks in the deep," said University of Georgia marine scientist Chuck Hopkinson. He headed the quick independent look by the Georgia Sea Grant program at the estimates the White House released.
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White House energy adviser Carol Browner said on morning news shows earlier this month: "More than three-quarters of the oil is gone. The vast majority of the oil is gone."
The Georgia team said it is a misinterpretation of data to claim that oil that is dissolved or dispersed is gone.
"The bottom line is most of it is still out there," Hopkinson told The Associated Press. "There's nothing in the report to substantiate the 26 percent."
But commercialsince the spill indicated their catch was plentiful and free of oil.
"We're not seeing any oil where I'm at. No tar balls, nothing," said Brian Amos, a 53-year-old shrimper who trawled in his 28-foot skiff, The Rolling Thunder, in a bay near Empire.
Laboratory tests on seafood from the Gulf have shown little hazard from oil, and a test is being developed for the chemicals used to disperse the crude, though there is no evidence they build up in seafood. Still, shrimpers are worried that the public won't want what they catch.
"I feel that we have had a bad rap on the perception of our product," said Andrew Blanchard, who waited Monday for shrimp boats to arrive at his processing plant in Chauvin. Fewer arrived than normal, five versus the usual 20 on a normal opening day, but he said that was because most boats are still doing cleanup work for BP, not because of any problem with the shrimp.