The Coast Is Not Clear

Visit the Gulf of Mexico today and you'd hardly recognize it as the scene of what President Barack Obama called "the worst environmental disaster America has ever faced." It's as if scientists had conducted an insane experiment—dumping some 4.9 million barrels of oil into the ocean water—and discovered that its effect was in some ways negligible. Some 21 years after the Exxon Valdez disaster, you can still find globs of oil in Alaska's Prince William Sound. Yet the Gulf appears to be scrubbing itself: Sunshine is evaporating—and bacteria are rapidly digesting—the spilled oil. Less crude has infiltrated vulnerable wetlands than was widely feared. Documented fish and bird kills have been small, and most Gulf beaches remain pristine.

Although serious concerns remain about the spill's long-term impact on coastal wetlands and deepwater creatures, the short-term trend is unmistakably positive: On Aug. 10 the National Oceanic & Atmospheric Administration (NOAA) announced it was opening an additional 5,000 square miles of the Gulf to fishing, leaving 22 percent of federal waters still closed. Harlon Pearce, who runs a wholesale seafood business in Kenner, La., says that with more fish and shellfish passing rigorous smell tests and chemical assays, "I really feel good that we're going to be getting into large production this September, October, and November." Morgan Stanley (MS) said on Aug. 3 that while the spill is a "significant shock to the regional economy," there will be "essentially no impact" on U.S. economic input this year or next.

That the Gulf is recovering does not mean all is well. It turns out that the disaster that transfixed the nation isn't the biggest threat to the Gulf's health. Environmental scientists point to more serious and persistent (albeit less telegenic) threats, including the continued loss of wetlands, the impact of global climate change, and the supercharging of the Gulf with fertilizer that flows down the Mississippi River from Midwestern farms. According to Larry McKinney, director of the Harte Research Institute at the Gulf-front Corpus Christi campus of Texas A&M University: "The spill is minor compared to those threats." It's as if a gunshot victim recovered from his wound, then had to battle metastatic cancer.

The patient has a fighting chance. Thanks to favorable winds and human intervention, little oil from the BP spill reached the estuaries where it can do serious damage. The light, sweet crude that stayed at sea is being disposed of rapidly by bacteria that have evolved to feed off the oil and methane that naturally seep from the seafloor. Roger Sassen, an adjunct professor of geology and geophysics at Texas A&M, goes so far as to say that "in a year or two we can forget this ever happened." Argues Sassen: "The fact that the Mississippi is the drainage ditch for the fertilizers and nasty agricultural chemicals of the entire central U.S. is much worse than this transient spill."

Even experts who are less sanguine see the oil spill as an added burden rather than a knockout blow. Jane Lubchenco, the marine ecologist who heads NOAA, says that the Gulf's waters and coasts "have been undergoing a series of changes over the years that have progressively compromised the health of more and more of the system." Speaking to reporters by phone on Aug. 10 while traveling in the region, she added: "Each of these changes doesn't happen in isolation. This spill interacts with and is on top of the other changes in the Gulf."

The Gulf's long-term nemeses can't be capped like a runaway oil well. Although slower-acting, they will have profound economic as well as environmental impacts, and responsibility for them can't be easily assigned. The Iowa corn farmer whose excessive use of fertilizer contributes to choking off oxygen in the gulf is harder to blame than, say, Tony Hayward, BP's (BP) outgoing chief executive.

The spill could do its worst damage by exacerbating existing threats. Harm to the bluefin tuna, prized both as a gamefish and as a culinary delicacy retailing for $100 a pound, is the premier example. It ranges the Atlantic but spawns just once a year: precisely where and when the BP spill occurred. The floating beds of brown seaweed that shelter bluefin larvae and fingerlings soak up oil like a sponge. Ocean biologists worry that the spill might have wiped out most of the 2010 generation of Gulf bluefins.

Ordinarily, the loss of a year's worth of fish might be tolerable. The problem: Severe overfishing in international waters of the Atlantic Ocean has already endangered the Gulf-spawning population of bluefins, down by 80 percent since 1970. (American fishermen landed a little less than 800 tons of bluefins in the West Atlantic in 2008, while other nations' fleets landed about 1,200 tons, according to the International Commission for the Conservation of Atlantic Tunas.) The spill could possibly push the bluefin population into outright collapse, says Robert L. Shipp, chairman of the Gulf of Mexico Fishery Management Council as well as the marine sciences department at the University of South Alabama. The only other population of the species, which spawns in the Mediterranean Sea, is also threatened.

The single biggest challenge to the Gulf's ecosystem may be the ongoing loss of wetlands, estimated at 25 to 30 square miles' worth per year. Estuaries and marshes provide shelter for commercially important crabs and shrimp. They also buffer humans from the impact of hurricanes and soak up the nitrogenous compounds from fertilizer and manure runoff that are borne down the Mississippi. Nitrogen that the wetlands don't capture feeds algal blooms. Bacteria that feed on the algae use up oxygen in the depths of the Gulf, creating a seasonal "dead zone" that's hospitable only to jellyfish, bacteria, and some worms. This month the Louisiana Universities Marine Consortium announced that the low-oxygen zone extended for 7,722 square miles, the fifth biggest on record.

What's unknown is whether oil from the spill will significantly accelerate the destruction of the wetlands. The wetlands are sinking because levees along the Mississippi's ship channel prevent silt from replenishing them. Pipeline channels have diced up the wetlands, further weakening them. When an area of wetlands finally sinks beneath the waves, it exposes an adjoining area to the waves' action, speeding up losses. Says McKinney: "If the rate of loss accelerates to 35 or 40 square miles a year, it will give us less time to come up with a restoration plan."

Global warming subtly worsens many of the Gulf's problems. Warmer Gulf waters are conducive to the spread of the voracious lionfish, a tropical Pacific fish with poisonous spokes that displaces native species, and the equally aggressive Chinese tallow tree, which has infested Gulf marshes. Plus, the shores of the Gulf lie so low that a sea level rise of just inches can inundate huge swaths of fertile coastline. (Seas have risen 8 inches in the past century, NOAA says.) The BP spill could potentially give more of a toehold to invasive species by weakening native ones, McKinney says.

Scientists studying the Gulf's health emphasize that all damage assessments are strictly preliminary, so the bad news might not be over. A female crab lays about 3 million eggs, of which a handful grow up to be crabs. Many of the rest are eaten by fish and other crabs. So when oil droplets and chemical dispersant showed up in the larvae of blue crabs, it was a danger sign for the whole food chain. Judy Haner, marine program director for the Nature Conservancy in Mobile, Ala., says damage to fish populations could take three to four years to manifest itself.

Another stubborn unknown is the impact of the spill on small fish, such as menhaden, sardines, small jacks, and anchovies, that are food for creatures higher up the chain. Anchovies and menhaden are filter feeders that swim with their mouths agape, catching tiny food particles in their gill filaments. The tiny oil droplets suspended in subsea clouds could kill the fishes' food source, the near-microscopic crustaceans called copepods. The droplets could also clog the fishes' gills. At the same time, oil-eating bacteria could exhaust oxygen supplies in deep waters. Next unknown: If fish in the plumes do die, will others occupy their niche as the pollution clears and oxygen increases? Shipp, of the University of South Alabama, says he thinks the spill should continue to be regarded as Public Enemy No. 1 for the Gulf until those kinds of questions are answered.

BP has agreed to set aside $500 million for environmental study in the Gulf, many times the normal level of spending. That ought to be enough to get to the bottom of things. "If BP has put the money aside like they say and they don't renege on their promises and the government doesn't strip the money for other purposes—and those are big ifs—there should be money for studies of this spill," says Edward Overton, an environmental chemist and professor emeritus at Louisiana State University. After that, the far greater challenge will be to apply the newfound knowledge to helping the resilient Gulf survive all of its many man-made wounds.

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