Damage from Exxon's oil spill lingered for decade, study says

By Kenneth R. Weiss
Los Angeles Times

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The 14-year study, published today in the journal Science, points out that effects of the 11 million-gallon spill into Prince William Sound extended well beyond the initial deaths of 250,000 oiled seabirds, 2,800 otters and 300 harbor seals.

The residual oil grew more toxic and continued to harm the coastal environment far longer than expected, the report says. These oily pockets are tucked beneath boulders or buried below gravel and mussel beds and have escaped sunlight, oxygen and waves that normally break it down.

"Because the Exxon Valdez spill happened in a biological wonderland of sea otters and harlequin ducks, there has been a huge amount of research," said Charles Peterson, the paper's lead author and a University of North Carolina marine biologist. "Things we have dismissed as sublethal effects actually translate into significant decline in wildlife."

For instance, the study compared the recovery of sea otters on heavily oiled shores of northern Knight Island with another island in the region that was not coated during the catastrophic spill. The population of sea otters that forage around Knight Island is half of what it was before the spill, while the population at the other island doubled between 1995 and 1998.

Otters suffer chronic exposure to toxic oil residue by eating contaminated clams and by digging into contaminated sandy ocean bottoms, according to the study.

Written by seven university and government scientists, the report was attacked as a bunch of "cartoon depictions" by Exxon Mobil officials before it was released.

"What science has learned in Alaska and elsewhere is that while oil spills can have acute short-term effects, the environment has remarkable powers of recovery," said Frank Sprow, Exxon Mobil's vice president of safety, health and the environment.

After Exxon Mobil spent $2.2 billion to clean up Prince William Sound and an additional $1 billion for environmental studies and conservation programs, it became clear that any remaining oil was safely encapsulated, he said.

"If it was leaching into the environment in ecologically meaningful quantities, it would be gone after 14 years," Sprow said. "You simply can't have it both ways."

	THE SEATTLE TIMES, 1989 An oil-soaked loon was found in Alaska's Prince William Sound.

The study, which included representatives of the National Marine Fisheries Service, the U.S. Fish and Wildlife Service, and the U.S. Geological Survey, notes "disagreements exist" between scientists funded by Exxon and those funded by the government. Furthermore, answers to some ecological questions remain uncertain.

"Nevertheless," the study's authors write, "these uncertainties do little to diminish the general conclusions: oil persisted beyond a decade in surprising amounts and in toxic forms ... and had long-term impacts at the population level."

The study focused on harlequin ducks because they are known to remain true to particular stretches of coastline and feed largely on snails and clams.

The authors found that far more adult females died during the winters from 1995 to 1998 on shores once covered with oil than did female ducks on shorelines untouched by the 1989 spill. They also found evidence — through a detoxification enzyme — in the ducks' blood stream that these colorful birds still were showing signs of exposure nine years later.

One particularly disturbing finding was that partially weathered oil appeared to be more toxic to fish than when it was fresh.

Combining laboratory experiments with field work, the scientists found that this highly toxic residual oil killed the embryos of pink salmon for at least four years after the spill. Pink salmon, which lay about half their eggs near the mouths of streams, are a key part of the food web in Alaska, including a prominent part of the diet for resident killer whales.

"Oil is different over time," Peterson said. "The stuff that is left over is extremely toxic, even at very low levels."

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