Scientific Army Finds This Spill Especially Lethal
GREEN ISLAND, Alaska (AP) _ The oil spill that has blackened much of the rich ecosystem of Prince William Sound has drawn an army of scientists who say a lethal combination of weather, topography and chemistry have conspired against the environment.
″This spill is unique,″ said Jacqui Michel, a National Oceanographic and Atmospheric Administration scientist helping to coordinate research efforts. ″It’s in a restricted inland bay. We’ve had this pool of oil sitting on top of the water for days.″
In addition, the cold water and rough waves have trapped chemicals that normally would evaporate from spilled crude oil.
The microscopic phytoplankton and zooplankton that form the basis of the marine ecosystem are especially sensitive to such toxins. And hydrocarbons even in tiny doses can kill salmon fry starting to emerge from streams and hatcheries around the sound.
″Every day, it’s getting a little worse,″ said otter rescue specialist Chris Donohoe. ″You clean a beach up, the tide changes, and the oil comes right back.″
Nearly 400 scientists are sampling water, collecting dead animals and monitoring beaches in an attempt to quantify what happens when 10 million gallons of crude oil gushes into a pristine marine environment.
The placid sound, protected from the stormy Gulf of Alaska by mountainous barrier islands, supports an abundance of wildlife.
But islands that keep stormy seas out can also keep oil in. Some tendrils of oil have been pushed by currents out into the gulf, but much of the 2,600- square-mile slick has stayed in the sound.
Birds soaked in oil lose their buoyancy and their insulation against the chilly water. When they desperately preen themselves, they ingest toxins.
Whales, seals and sea lions have been seen swimming through the oil and appear to be staying healthy.
But while most marine mammals depend on a thick fat layer for insulation, sea otters keep warm by trapping air in their dense, soft fur and they must keep that fur clean to survive.
At least 40 dead sea otters have been found and an additional 40 or so have been captured after coming ashore to try to warm up and wash themselves.
″We see them up on the snow, rubbing snow on themselves, trying to get the oil off,″ said rescuer Elwin Johnston. ″It’s pathetic.″
Oily bird carcasses are tempting but toxic meals for scavenging bald eagles, bears, mink and land otters.
When the tide recedes, a glistening black sheen is left on the intertidal zone, between high and low tide marks, suffocating kelp and eel grass.
Hardy intertidal creatures have adapted to survive long dry spells, but they cannot handle prolonged exposure to oil. Mussels, for example, close their shells tightly when they sense toxins in the water.
″They can close down for four or five days, but then they have to open. If the oil’s still there, they die,‴ said Steve Zimmerman, a biologist with the National Marine Fisheries Service.
Field crews studying some of the 800 miles of shoreline fouled so far have found many intertidal organisms in advanced stages of distress. Some are losing their grip on the rocks and being washed away.
″I don’t think we’ll see completely bare rocks. But a lot of animals will die, and there will be less for other animals to feed on,″ Zimmerman said.
Perhaps the greatest ecological danger of the Prince William Sound oil spill is the invisible toxins that dissolve into the water, scientists said.
Crude oil contains toxic and carcinogenic hydrocarbons such as benzene, toluene and xylene. Usually these compounds evaporate within 48 hours of an oil spill.
But the cold water of Prince William Sound slowed evaporation. And high wind three days after the accident whipped much of the slick into a frothy mix of oil, water and air that may have helped trap those volatiles.
In addition, the Prudhoe Bay crude oil that spilled has unusually high levels of heavier hydrocarbons such as naphthalene, a more persistent toxin. Such hydrocarbons can stick around for years, sinking into sediments.
″Eventually all the oil will go away,″ Michel said. ″But it may be a long time.″