Mourners bowed their heads at vigils yesterday to mark the first anniversary of the massive blowout on BP’s Deepwater Horizon rig, which unleashed the biggest maritime oil spill in history and blackened beaches from Texas to Florida.

President Barack Obama vowed to do “whatever is necessary” to restore the US Gulf Coast and to “hold BP and other responsible parties fully accountable for the damage they’ve done and the painful losses that they’ve caused.”

Oil-coated dolphin carcasses and sticky tar balls continue to wash up on beaches a year after the April 20, 2010 explosion which killed 11 workers and sank the Deepwater Horizon some (80 kilometres off the coast of Louisiana.

By the time the well was capped 87 days later, 4.9 million barrels of oil had gushed out of the runaway well 5,000 feet below the surface of the Gulf of Mexico.

Hundreds of miles of fragile coastal wetlands and beaches were contaminated, a third of the Gulf’s rich US waters were closed to fishing, and the economic costs have reached into the tens of billions.