Look: all over the planet, oil seeps from underground and into the oceans. Lots of it. Like, the entire BP oil spill, all hundred days of it, every day. But it's everywhere, not just in one spot.
The theory of evolution teaches us that whenever there is a food or energy source available that is not being competed for, some form of life will adapt to exploit that source. That's why we find "extremophile" bacteria near deep ocean vents and in the boiling, acidic waters of thermal springs like those at Yellowstone. Oil seeping from the bottom of the ocean is an energy source; we wouldn't be in this mess if it weren't. It's a nice dense source of energy; and there are bacteria which like nothing better than tearing into hydrocarbon molecule chains.
So what happens? There's a bloom of oil-eating bacteria for a while in the Gulf of Mexico; and as the food source depletes, the bacteria die off. The bacteria themselves convert petroleum into other things (amino acids, protiens, etc) and other lifeforms eat the bacteria. This is called the food chain and every organism on the planet has a place in it.
We've seen this startlingly fast bioremediation take place before, every time there's been an oil spill. Most noteworthy is Prince William Sound (Exxon Valdez) which--we were told--would be an ecological disaster for decades...and which, instead, was spic-and-span in a matter of a couple of years.
Crude oil is not some horrible, poisonous substance which only comes to the surface when Man starts screwing around with the planet. It's a natural byproduct of a natural process; it naturally enters the biosphere in limited quantities entirely without Man's help, and there are organisms which take advantage of it.
"It is still far too early to know how much damage the spill has done — and may still be doing — to the environment. Tar balls continue to wash up on beaches." You can pick up a tar ball and put it in a plastic bag.
End result: next year it'll be as if the spill had never happened. Same as with Prince William Sound.