Extensive sampling of the Gulf of Mexico seafloor has found oil in quantities too small to collect and in concentrations below harmful levels, except in the area surrounding the BP well, federal scientists say.
The Coast Guard’s report contrasts with 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,” Rear admiral 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 a mile and a half of the BP well, where oil is bound with drilling mud pumped into the BP well to cap it.
The BP well, about 80km offshore from Louisiana, was plugged in September, but not before more than 772M.l of oil leaked into the Gulf.
Still, government scientists said the report was a guide for the Coast Guard and clean-up 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 clean-up 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 Admiral Zukunft transferring oversight of the clean-up to Captain 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 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 3 August, the report said less than 1% of water and sediment samples exceeded levels the Environmental Protection Agency considers harmful to aquatic life.
But scientific support co-ordinator for the National Oceanic and Atmospheric Administration Charlie Henry said even very low concentrations of oil could have “latent, long-term chronic effects” on marine species.
Scientists were cautious and even sceptical about this latest report.
Oceanographer at Florida State University Ian R MacDonald 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 128km² 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 clean-up commander.