WHAT THE OIL PLUMES WILL KILL

From Susan D. Shaw in the New York Times:

FOR the last few days, attention has understandably been directed at the shores of the Gulf Coast as oil has started to wash up on beaches and in marshes. But last week I had the chance to see the effects of the spill from another perspective — when I dived into the oil slick a few miles off the Pass a Loutre wetlands in southern Louisiana. What I witnessed was a surreal, sickening scene beyond anything I could have imagined.

As the boat entered the slick, I had to cover my nose to block the fumes. There were patches of oil on the gulf’s surface. In some places, the oil has mixed with an orange-brown pudding-like material, some of the 700,000 gallons of a chemical dispersant called Corexit 9500 that BP has sprayed on the spreading oil. Near Rig No. 313, technically a restricted zone, the boat stopped and I (wearing a wetsuit, with Vaseline covering exposed skin) jumped in.

Only a few meters down, the nutrient-rich water became murky, but it was possible to make out tiny wisps of phytoplankton, zooplankton and shrimp enveloped in dark oily droplets. These are essential food sources for fish like the herring I could see feeding with gaping mouths on the oil and dispersant. Dispersants break up the oil into smaller pieces that then sink in the water, forming poisonous droplets — which fish can easily mistake for food.

Though all dispersants are potentially dangerous when applied in such volumes, Corexit is particularly toxic. It contains petroleum solvents and a chemical that, when ingested, ruptures red blood cells and causes internal bleeding. It is also bioaccumulative, meaning its concentration intensifies as it moves up the food chain.

Further from Newsweek:

These undersea rivers of oil, though not nearly as concentrated as oil at the surface, are likely to affect the gulf through two mechanisms. The first is oxygen depletion, which has been estimated at 30 percent in the plumes. The other will be direct toxic effects of the oil and methane. Leatherback turtles and sperm whales dive to the 3,200-foot depths where plumes have now been detected, and aren't smart enough to take evasive action. "They don't necessarily recognize the plumes as something dangerous," says marine scientist Ellycia Harrould-Kolieb, who works with the green group Oceana. Sharks, shrimp, and squid are all inhabitants of the deep, which would protect them from a Valdez-type spill on the surface, but now puts them in the crosshairs. Marlin, snapper, and grouper swim hundreds of feet down. One of the biggest losses may be bluefin tuna. Already imperiled from overfishing, the species breeds only in the Mediterranean Sea and the gulf. "This could spell the end to bluefin," says Harrould-Kolieb. Even small bits of crude, like those in the plumes, can suffocate fish by gunking up their gills.

Other species imperiled by the deep-sea plumes include those that migrate down from the surface and others that make the reverse commute. "There are plankton that go from the surface to the middle of the water column, and other things eat them and go down deeper, and other things eat them and go to the bottom," says oceanographer Lisa Levin of Scripps Institution of Oceanography. "All the zones of life interact, and now they're probably all being hammered."

The worst effect of large-scale death on the gulf floor is nothing as photogenic as dead pelicans, but much more pernicious. "The organisms most likely to be harmed by the oil plumes are those at the base of the food chain," says biological oceanographer Andrew Juhl of Lamont-Doherty. "Most of the primary producers, such as phytoplankton, live throughout the water column. Effects on them would cascade to the larger species we care about."

To hear those who know say that the oil in the marshes and on the beaches, and the oil-covered birds and turtles demonstrate the least of the damage from the oil gushing into the Gulf, is sobering, infuriating, and depressing. What we will see is killing on a grand scale. Marine biologist Jeffrey Baguley of the University of Nevada says, "In the time scale of man, this will be a catastrophic event".