Bay St. Louis, Mississippi: 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 (200 million litres) of the leaked oil from BP's Deepwater Horizon well are gone.
The report issued on Wednesday says the clean-up extracted a lot of it, but the natural processes that break up, evaporate and dissolve oil took care of 84 million gallons (317 million litres) — more than twice the amount human efforts removed.
At the same time, more progress was made in sealing the well for good as BP finished pumping cement into it on Thursday.
The Gulf's impressive self-clean-up 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 per cent of America's runoff pours from the Mississippi River into the Gulf.
Buffet of life
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 Centre for Marine Biodiversity and Conservation at the Scripps Institution of Oceanography, is worried.
Major disturbance
"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. The currents and drainage are right to flush and dilute tainted water.
And the Gulf has long been exposed to natural gas, oil and a host of other contaminants.
While BP's well dumped 172 million gallons (651 million litres) into the Gulf over three months, the muddy Mississippi brings in 198 million gallons (750 million litres) of water — replete with urban and farm run-off — every minute. The National Research Council estimates that 41 million gallons (155 million litres) 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 immunised 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.
Assessments
It's still early in damage assessments, but so far about 965 kilometres 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. Federal and BP officials are scurrying to conduct damage assessments from the spill.
The first and crucial step to such assessments is figuring out the condition of the Gulf before the spill.
"A baseline is the medical history of the environment," said Smithsonian scientist Nancy Knowlton. "Without a baseline you can't say anything about what the impact of anything is."
Effects on seafood could pose health risk
Oil from BP Plc's blown-out well has stopped flowing into the Gulf of Mexico and so far there is little sign of the 1.8 million gallons of dispersants used to combat the oil slick.
But experts say very little is known about what their long-term effects might be, either on the creatures living in the Gulf or the people who eat them.
Test results released by the Environmental Protection Agency on Monday showed that Corexit 9500, the main dispersant used, is less toxic to some sensitive species of sea life than Louisiana sweet crude oil and that oil and dispersant mixture is no more toxic than oil by itself.
And the dispersants themselves have not been found in any near-shore species of fish, and would be unlikely to pose a health risk in seafood, according to the Food and Drug Administration.
"The constituents of dispersants are highly unlikely to get into the flesh of the fish," said the FDA's Don Kraemer.
However, a panel of scientists testifying at a Senate hearing on Wednesday cautioned that the long term effects of dispersants are largely unknown.
"A massive ecotoxicological experiment is underway," Ronald Kendall, director of the Environment and Human Health Institute at Texas Tech University, told the Environment and Public Works Subcommittee on Oversight.
