The Dead Zone

"Scientists say there is a 30km long, 10km wide plume of oil about a kilometre under the water, potentially sucking up all the oxygen there, killing plankton ... creating a sort of dead zone in the Gulf of Mexico that will be spreading," our correspondent said.
Scientists from several universities have reported plumes of what appears to be oil suspended in clouds stretching for kilometres and reaching hundreds of metres beneath the Gulf's surface.
The findings - from the University of South Florida, the University of Georgia, Southern Mississippi University and other institutions – were based on initial observations of water samples taken in the Gulf over the last several weeks

James Cowan, a marine scientist at Louisiana State University, who reported finding a plume last week of oil about 80km from the spill site that reached to depths of at least 122 metres, said "there's been enough evidence from enough different sources".
But Tony Hayward, BP's chief executive, disputed the scientists' claims, saying BP's sampling showed "no evidence" that oil was suspended in large masses beneath the surface.
"The oil is on the surface," Hayward said. "Oil has a specific gravity that's about half that of water. It wants to get to the surface because of the difference in specific gravity."
In the six weeks since an explosion hit BP's Deepwater Horizon drilling rig, killing 11 workers, the leaking well has spewed an estimated 68 million litres of oil into the Gulf of Mexico.
The spill is the worst in US history - exceeding even the Exxon Valdez disaster in 1989 off the Alaska coast.
BP says it has so far spent $940m to try to plug the leak and clean up the sea and soiled coast.
The top kill operation, which involved pumping mud into the well - most of which escaped out of the well's damaged riser pipe - was the latest of several failed attempts to plug the leaking well.
In the days immediately after the explosion BP engineers tried to use robot submarines to close valves on the massive blowout preventer atop the damaged well.
Two weeks later ice-like crystals clogged a 100-tonne containment box the company tried placing over the leak.
And earlier this week engineers removed a mile-long siphon tube from the broken riser pipe after managing to extract a disappointing 3.4 million litres of oil from the well.