Disaster in the Gulf: SW Florida’s wildlife and beaches imperiled

The images are agonizing fishermen facing ruin, their lives in jeopardy. Sea turtles surfacing through swirls of floating oil. Doomed dolphins struggling in the discolored surf. Disoriented pelicans being cleansed by overworked volunteers. Beachgoers saying that they're on their favorite patch for one last time. Disaster looms over one of America's most fragile ecosystems.

Fifty miles to the south, disaster had struck days earlier. Eleven men lost their lives when one of the world's technologically most advanced and operationally safest oil rigs, the Deepwater Horizon, suffered a series of devastating explosions that sank the vessel and left its newly drilled wells gushing oil into the waters of the Gulf of Mexico by the conservative estimate of 5,000 barrels daily. As a growing patch of thickening oil formed over the accident's epicenter, the coastline's only ally was the wind. Northerly breezes slowed the oil's advance on the Mississippi Delta and nearby shores, where workers floated miles of orange-colored floating "booms" to keep it offshore. But when British Petroleum's first effort to cap one of the Horizon's gushing wells failed three weeks after the explosions, the writing was on the wall. This would be no contained spill. The question was how much of the Gulf of Mexico would be despoiled.

It's worth looking at a map to gauge the prospects. In common with other large water bodies in the Northern Hemisphere, the Gulf of Mexico has a clockwise circulation, its waters being augmented via the Strait of Yucatan between western Cuba and the Yucatan Peninsula and leaving to join the Gulf Stream through the Florida Strait between the tip of Florida and Cuba's north coast. If nothing else affected the Gulf's circulation, the oil slick would move eastward along the Florida panhandle, then southward along the peninsula's west coast and eventually eastward into the Atlantic. Indeed, some television commentators projected just such a scenario, suggesting that the oil would ultimately affect East Coast beaches, travel north in the Gulf Stream, and reach as far north as Cape Cod.

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But the situation is more complicated than that. While dominant circulation patterns driven by Coriolis force - generated by the Earth's rotation - do create clockwise gyres in the Northern Hemisphere (and counterclockwise in the Southern Hemisphere, for those of us who remember being taught the old wives' tale of the bathtub drain running in reverse down-under), surface patterns are far more affected by prevailing winds and other factors. In the case of the Gulf of Mexico, the salinity of coastal waters is affected by the two major rivers, the Mississippi and the Rio Grande, creating vertical as well as horizontal circulations. The submarine topography of the Gulf of Mexico, which is much deeper in the west than in the east, also comes into play. The shallower eastern Gulf increases its potential vulnerability to oil pollution.

So there is no simple answer to the question of risk. Are the beaches and ecologies of Southwest Florida in danger? Not yet, but the longer the oil gushes into the Gulf, the greater the danger will obviously be.

Will wind directions help alleviate the risk created by the fundamental circulation of the Gulf's waters? Since this appears now to be a crisis that will endure for months, it is relevant that summer is the time when the easterly trade winds are strongest, and their effect is likely to be to push oil slicks away from Southwest Florida shores. But all westward-moving pressure systems, being circular, have eastward components, and there will be times when the same Gulf breezes we covet on Boca Grande will have the potential to bring oil to our shores unless BP somehow manages to stem the flow of oil.

At the time of writing, that does not look likely. So the short answer to the question is: yes.