Greater cancer rates in the human population in the states that border the gulf coast as the cancer causing chemicals (aromatic hydrocarbons etc) make their way up the food chain over a period of 1-10 years. The natural environment will recover to some extent but can take around 20 years if left to its own devices. The oil release won't help recovery of the dead zone found previously around the Mississippi delta in the Gulf due to the long term agrochemicals pollution, it will just increase the size of the dead zone.

NASA satellite photo of the Gulf Coast Dead Zone