Gulf Coast oil spill could eclipse Exxon Valdez

"It is of grave concern," David Kennedy of the National Oceanic and Atmospheric Administration, told The Associated Press. "I am frightened. This is a very, very big thing. And the efforts that are going to be required to do anything about it, especially if it continues on, are just mind-boggling."

The oil slick could become the nation's worst environmental disaster in decades, threatening hundreds of species of fish, birds and other wildlife along the Gulf Coast, one of the world's richest seafood grounds, teeming with shrimp, oysters and other marine life. Thicker oil was in waters south and east of the Mississippi delta about five miles offshore.

Gulf Coast oil spill could eclipse Exxon Valdez | World news | guardian.co.uk

BP's stock has fallen about 15 percent since the rig blast on April 20, wiping about $30 billion from its market value.

"The one thing we know with certainty is that ... there was a sudden, catastrophic failure of the cement, the casing or both," according to Newman's prepared remarks.

Transocean's Newman also said the rig blew three days after the drilling was completed and the well had been sealed with cement. The workers above never knew what hit them.

"It is also clear that the drill crew had very little (if any) time to react," Newman said. "The explosions were almost instantaneous."

With attempts to contain the oil spill unsuccessful so far, some lawmakers have questioned the adequacy of the companies' response to the accident.

David Nagel, executive vice president for BP America, on Monday defended his company's response to the accident.

"In terms of the spill response: that was mobilized right away," Nagel told reporters at a press briefing in Washington. He said the failure of Transocean's blowout preventer was what "turned this incident into a really tragic situation."

"This was the last step in a series of safety steps to control the situation ... and it was expected to work," Nagel said.

Oil executives set to face US Congress over oil spill - Americas, World - The Independent

"But my concern is that the oil - which is a toxic substance - could have a very negative impact on shrimps, fish, oysters and crabs in the Delta. The development of the young, the juveniles - if exposed to oil - could be very strongly impacted."

Swamps and marshes in the Mississippi Delta provide 40 percent of US seafood production.

"One way or the other there will be consequences," Griffitt warned, noting that fish die in a high concentration of oil, such as at the rate of one part of oil for 10,000 parts of water.

Even when there is a lower concentration of toxic products, organs can be damaged.

"If you take a fish, and oil - too much oil - finds its way into his organism, the liver is not able to detoxify the oil anymore," the biologist said. "The same goes for other organs like the brain and the gonads. The development of the young can also be damaged, and that's my main concern."

US oil spill no Chernobyl, but still toxic: biologist - Environment - The Independent