On the rocky beaches of Alaska, scientists plunged shovels and picks into the ground and dug 6,775 holes, repeatedly striking oil — still pungent and dangerous a dozen years after the Exxon Valdez infamously spilled its cargo.

More than an ocean away, on the Breton coast of France, scientists surveying the damage after another huge oil spill found that disturbances in the food chain persisted for more than a decade.