For Louisiana in particular, a key area of concern is coastal marshes. They are the breeding ground as well as home base for a wide range of marine life vital to the region’s fishing industries. Moreover, the wetlands provide a first barrier against storm surges from hurricanes.
But southern Louisiana’s wetlands already are stressed – vanishing as the Mississippi Delta sinks beneath the ocean at a rate that, by some estimates, averages 50 acres a day. In addition, the fisheries off the coast are exposed to an annual “dead zone” each spring as nutrient-rich water from the continental heartland moves down the Mississippi and into the Gulf, triggering algae blooms. When the algae die and decompose, the process uses up much of the dissolved oxygen in the water. Fish flee, but bottom dwellers – crabs and other shellfish – generally can’t move fast enough to do so.
If the blowout “turns into something that takes months to shut off ... that is our biggest concern,” says James Cowan Jr., a fisheries ecologist at Louisiana State University in Baton Rouge. With the ecosystem already distressed, “We are concerned it may be at a tipping point.”
In trying to assess the potential effect of oil on the Gulf Coast wetlands, a 1969 spill in Massachusetts’ Buzzards Bay might offer close – if still imperfect – parallels, say Dr. McDowell and Woods Hole colleague Christopher Reddy.