BELLE CHASE, La. | From a seaplane 1,000 feet above Louisiana’s coastal wetlands, the places hit hardest by the Gulf of Mexico oil spill are easy to spot — dark slashes marring a vast expanse of marshes and bayous.
Yet more than two months after the spill started, the view appears to confirm what many scientists are concluding: The wetlands, a haven for fish and seabirds and a flood buffer during the Gulf’s notoriously vicious storms, “have come through so far pretty unscathed,” Paul Kemp, director of the National Audubon Society’s Louisiana Coastal Initiative, said after a recent 260-mile flight over most of the affected sections.
Damage has been severe in some locations, especially in reedy swamps near the mouth of the Mississippi River. But it’s spotty and confined mostly to outer fringes of islands topped with marsh grasses and mangrove bushes. Little oil has advanced more than a few yards toward the interior, despite the many openings created by a labyrinth of natural bayous and man-made canals.
“There may be a few areas where the oil has penetrated deeper into the marsh, but I have not seen them yet,” said Irving Mendelssohn, a Louisiana State University coastal-plant ecologist.
Favorable wind and tidal patterns, plus Mississippi River currents countering the oily flow from the Gulf, have spared the wetlands the worst of the oil, experts say.
That could change quickly if a hurricane or tropical storm hurls an oil-choked water surge inland. Tropical Storm Alex, forecast to become a hurricane this week on its way between the Yucatan Peninsula and the U.S.-Mexico border, was not expected to spread the oil much more widely than it already is, but the next storm might.
“We’ve got some bad weather out there, and God knows what will happen next,” said Jacqueline Michel, a National Oceanic and Atmospheric Administration contractor who coordinates teams patrolling the wetlands.
For now, there has been nothing approaching wholesale saturation of Louisiana’s estuaries, nesting grounds for brown pelicans, ducks and endangered least terns and a buffer that protects population centers from tidal surges during severe storms.
Wetlands are also prized for their ability to filter and store pollutants, so it makes sense that they’ve managed to keep the oil along the fringes, said Alex Kolker, a Tulane University scientist.
“In this case, it may be a sacrificial sort of filtering, because they’re taking on so much oil they may die off,” Mr. Kolker said.
Wherever the oil has reached, swamp grass has turned a sickly brown and once-leafy mangrove shrubs are bare skeletons.
On Queen Bess Island, a bird rookery in sprawling Barataria Bay, waves of oil vaulted over rows of protective boom and fouled the island’s exterior a couple of weeks ago. On a recent morning it still swarmed with seabirds, some with stained plumage. Scientists have observed chicks awash in oil there. And the worst may be happening under the water.
If oil seeps into the ground and suffocates roots, the plants will die and soil will wash away, worsening erosion that already swallows up to 30 square miles of Gulf coastal wetlands a year — a football field every half-hour.
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