BAY ST. LOUIS, Miss. -- Want to know the future of the oil-stained Gulf of Mexico ecosystem? Look first to its muddy, polluted past.

The recent ecological history of the Gulf gives scientists reason for hope. In an extensive survey of Gulf of Mexico researchers by The Associated Press, at least 10 of them separately volunteered the same word to describe the body of water: "resilient."

This is buttressed by a government report that claims that all but 53 million gallons of the leaked oil from BP's Deepwater Horizon well are gone. The report issued Wednesday says the cleanup extracted a lot of it, but the natural processes that break up, evaporate and dissolve oil took care of 84 million gallons -- more than twice the amount human efforts removed.

The Gulf's impressive self-cleanup makes sense given its history and makeup. The Gulf regularly absorbs environmental insults: overfishing, trawlers raking sea floors, frequent hurricanes. And then there's the dead zone, an area starved of oxygen because 40 percent of America's runoff pours from the Mississippi River into the Gulf.

And yet the Gulf remains America's most biologically diverse place, with 15,419 species. It is the nation's buffet of life as well as its gas station and septic tank.

It's too soon to know the full effects of the BP disaster. But to get a sense of where the Gulf has been and where it's going, the AP surveyed 75 scientists about the health of the Gulf of Mexico before the spill. On a 0-to-100 scale, the scientists graded its general health a 71 on average. That's a respectable C, considering 100 would be considered pristine and untouched by civilization.

"If having a strong system in place pre-spill makes a difference, and I think it might, then I think the system may bounce back sooner than expected," said Brian Crother, a Southeastern Louisiana University wetlands biologist.

But nothing about the Gulf is simple. Just as often as scientists use the word "resilient," they use the word "stress."

"The Gulf of Mexico has been fairly resilient, but it's been under stress," Michael Carron, director of the Northern Gulf Institute, said as he steered his boat around the Bay St. Louis waters.

In the survey, which was sent to scientists through several research institutions and scientific societies, sea turtles, manatees, wetlands and water quality hovered around or below the failing point. Doing well were beaches and birds, including the once-endangered brown pelican, Louisiana's state bird.

While others are optimistic, Jeremy Jackson, director of the Center for Marine Biodiversity and Conservation at the Scripps Institution of Oceanography, is worried.

"You have an ecosystem that's already severely stressed, then you add this major disturbance," he said. "We're going to pay for our sins double-time because we've neglected the environment of the northern Gulf so badly for so long."

Yet the Gulf's water is warm, which is good for microbes that eat oil.

While BP's well dumped 172 million gallons into the Gulf over three months, the muddy Mississippi brings in 198 million gallons of water -- replete with urban and farm runoff -- every minute. The National Research Council estimates that 41 million gallons a year of oil naturally seep into the Gulf from below.

A thriving microbial ecosystem has developed to consume the oil.

"The Gulf has been immunized many times by environmental insults," said Larry McKinney, director of a Gulf research center at Texas A&M University Corpus Christi. "Because of that resilience we see here -- and not in other places -- it also may be the best place" to cope with a gigantic spill.

It's still early in damage assessments, but so far about 600 miles of coast has been fouled with oil. The official government death toll so far: 3,606 birds, 508 endangered sea turtles and 67 marine mammals. More than 2,100 birds, turtles and marine mammals have been found oiled, but alive.

But those are only the losses seen. Scientists suspect many more animals have died, but their bodies have not been found.

An analogy that many of the experts said is apt for the entire Gulf is one of a champion boxer who takes devastating hits.

The Gulf "keeps getting knocked down. You can only get knocked down so many times before you don't get back up," Texas A&M's McKinney said. "The Gulf has gotten knocked down many, many times. You've got dead zones, habitat loss, you've got overfishing. You've got hurricanes keep coming. At what point do you get the tipping point?"