NEW ORLEANS – Federal scientists said Friday extensive sampling of the Gulf of Mexico seafloor found oil in quantities too small to collect and in concentrations below harmful levels, except in the area surrounding the BP well.
The Coast Guard's report contrasts independent scientists who say oil from the BP spill extensively damaged the seafloor and killed coral, sea fans and many bottom-dwelling animals like tubeworms.
"We are not finding any recoverable amounts of oil" on the seafloor, Rear Adm. Paul Zukunft said. "We are dealing with barely detectable amounts of oil in the parts per billion in many places."
He said the tiny amounts of oil fall well under pollution limits, except for the area within 1 1/2 miles of the BP well, where oil is bound with drilling mud pumped into the BP well to cap it, Zukunft said.
The BP well, located about 50 miles offshore from Louisiana, was plugged in September, but not before more than 170 million gallons of oil leaked into the Gulf.
Still, government scientists said Friday's report was a guide for the Coast Guard and cleanup crews, not an assessment of the spill's damage to the ecosystem.
The Coast Guard report was a summary of 17,000 water and sediment samples taken between May and October. The report said no further cleanup offshore was warranted and efforts should focus on tar and oil residue buried in the sand along the shore.
The report's release coincided with Zukunft transferring oversight of the cleanup to Capt. Lincoln Stroh. The Coast Guard also said it would move into long-term response overseen by regional Coast Guard units.
Oil in sediment samples could not be traced back to the BP well in all cases except for those taken near the well, the report said. In many places, the traces of oil could have come from other sources, such as natural oil seeps and even other oil leaks.
Since Aug. 3, the report said less than 1 percent of water and sediment samples exceeded levels the Environmental Protection Agency considers harmful to aquatic life.
But Charlie Henry, a scientific support coordinator for the National Oceanic and Atmospheric Administration, said even very low concentrations of oil could have "latent, long-term chronic effects" on marine species.
Scientists were cautious and even skeptical about this latest report.
Ian R. MacDonald, an oceanographer at Florida State University, said a recent submarine dive found what appeared to be lots of oil and dead animals on the sea floor at a spot very close to where the government said it barely found any oil.
"We went to the same place and saw a lot of oil," MacDonald said. "In our samples, we found abundant dead animals. It points out that different people — trained scientists — can get different answers."
MacDonald estimates that an 80 square mile area of seafloor around the well has been damaged by oil.
Ernst Peebles, an oceanographer at the University of South Florida, said researchers there have found anomalies on the Gulf floor. "The story (of what is happening) on the bottom is just starting," he said.
The report was hailed by BP as evidence the Gulf was making a strong comeback.
"The scientific evidence in this report is consistent with our observations that the beaches are safe, the water is safe and the seafood is safe," said Mike Utsler, BP's cleanup commander.