An excerpt from Greenwire:

The Gulf of Mexico’s undersea oil plume is no more.

For nearly a month, scientists sampling the site of a deepwater plume stretching southwest from BP PLC’s failed well in the Gulf have been foiled. Their sensors have gone silent. Where once a vibrant — if diffuse — cloud of oil stretched for miles, 3,600 feet below the surface, there is now only ocean, and what seems to be the debris of a bacterial feeding frenzy.

“For the last three weeks, we haven’t been able to detect the deepwater plume at all,” said Terry Hazen, a microbiologist and oil spill expert at Lawrence Berkeley National Laboratory who has had a clutch of researchers monitoring the Gulf since late May. The disappearance is backed up by government sampling data. The plume is simply gone. And Hazen knows why.

“This all fits with the fact that the bugs have degraded the oil,” he said.