ATLANTA, Ga. — Work crews continued their attempts Monday to stanch the 1,000 barrel-a-day oil spill that is gushing beneath the deep waters off the Louisiana coast, as communities along the Gulf of Mexico braced for the possibility of polluted beaches and fisheries that are crucial to the region’s economy.

Throughout the day, technicians maneuvered remote-controlled submarines around the leaking well left by the Deepwater Horizon drilling rig, which sunk Thursday after an explosion and fire. Their goal was to seal off the well by manually activating a 450-ton mechanism called a blowout preventer.

As of Monday afternoon, they had not succeeded, in part due to the difficulties of working at about 5,000 feet below the water’s surface.

“It’s a very challenging work environment,” said Doug Suttles, chief operating officer for exploration and production for BP, which leased the rig — and is now responsible for the as-yet-undetermined cleanup costs.

The company was taking other steps to try to deal with the spill if the submarines prove ineffective. The company has filed permits with the federal government to drill new relief wells that could intersect with the original well and stop the leaking.

Construction has also begun on a domelike collection device that could be positioned over the leak to capture the oil, then send it through pipes to a barge on the surface.

But oil company officials said that both of these solutions would take several weeks to be realized.