Published: Jun 01, 2010 5:17 PM EDT
Updated: Jun 01, 2010 2:17 PM EDT

NEW ORLEANS (AP) - The Coast Guard is replacing the admiral who has been the federal on-scene coordinator since an oil rig exploded and millions of gallons of crude leaked into the Gulf.

The spill's unified command center said in a news release Tuesday that Rear Adm. Mary Landry will return to duties as commandant of the 8th Coast Guard District in New Orleans to focus on hurricane season preparations. Her replacement is Rear Adm. James Watson, who joined Landry as deputy on-scene coordinator three days after the rig exploded April 20.

Coast Guard commandant Adm. Robert Papp says in a statement that Landry's relief had been planned since the start of the response. Coast Guard Adm. Thad Allen, the national incident commander, praised Landry's performance.

BP lost billions more in market value Tuesday as its shares fell steeply on the first trading day since the weekend failure of its latest bid to cap the massive Gulf of Mexico oil spill.

As the British oil giant turned to yet another unproven technology to try and contain the gusher, its share price, which has fallen steadily since the start of the disaster, took a turn for the worse, losing 15 percent to $6.13 in early afternoon trade on the London Stock Exchange.

That was the lowest level in more than a year. The shares have now lost more than a third of their value, wiping some $63 million off BP's value, since the explosion at the Deepwater Horizon oil rig six weeks ago. BP said early Tuesday it had spent $990 million so far on fighting and cleaning the spill, with multiple lawsuits for damages yet to be tallied.

With the ambitious "top kill" having failed over the weekend and a relief well at least two months away, BP turned to another temporary fix, an effort to saw through the pipe leaking the oil and cap it that could be tried as soon as Wednesday.

In the meantime, more than 125 miles of the state's coastline already have been hit with oil, including the resort of Grand Isle near Port Fourchon. The cleanup, relief wells and temporary fixes were being watched closely by President Barack Obama's administration.

Obama planned to meet for the first time Tuesday with the co-chairmen of an independent commission investigating the spill, while Attorney General Eric Holder was headed to the Gulf Coast to meet with state attorneys general.

Obama's energy czar, Carol Browner, said she doesn't want to guess the prospects for success when BP again tries to use a containment cap to control the oil spill. Interviewed Tuesday on ABC's "Good Morning America," Browner said, "I don't want to put odds on it. ... We want to get this thing contained." Browner also said she's concerned about the effect the hurricane season, which began Tuesday, could have on ending the environmental crisis.