A year after BP's Deepwater Horizon drilling rig exploded, killing 11 workers and spewing almost 5 million barrels of oil into the Gulf of Mexico, researchers are still assessing the damage. Much visible oil has been cleaned up, but dozens of dead dolphins and sea turtles have washed ashore, and some residents say exposure to toxic chemicals during the cleanup made them sick. While fish have been given a clean bill of health, demand for local seafood is lagging, and thousands of claims for lost income are pending. BP is likely to owe billions of dollars in penalties, money that could help restore the region's oil-damaged environment. But experts say eroding wetlands and pollution in the Mississippi Delta — caused by industrial activity and misguided flood-prevention efforts — also demand attention. Restoring the Gulf's unique ecological resources, many advocates say, will also strengthen communities — crucial in a region that has long suffered from poverty and economic inequality.