MUSSELS COVER OIL FROM SPILL
STATE STUDIES EFFECTS ON OTTERS, SEA BIRDS

By NATALIE PHILLIPS
Daily News reporter

DISK ISLAND- One of the most startling discoveries during oil-spill cleanup work last summer was that perfectly preserved oil sometimes up to 4 inches deep was locked under some mussel beds in Prince William Sound. After a winter of comparing notes, oil-spill scientists now suspect that contamination of that food source may explain why harlequin ducks are not reproducing and black oystercatchers, river otters and juvenile sea otters are not thriving.

"We're saying, 'Of course, how could we have been so blind?' " said Mark Brodersen, oil-spill restoration chief with the state Department of Environmental Conservation. "The oil is there and that was a surprise. . . . Late last summer, when we started looking for possibilities as to why we were seeing low reproduction in the harlequin ducks, we started thinking it might be the oil beds."

To find out, $874,000 of oil-spill settlement money will be spent this summer on four studies. Scientists will trap oystercatcher chicks and harlequin ducks and examine their blood and feces. At the same time they will try to determine how widespread the problem is and they will start exploring ways to get the trapped oil out from under the beds. Study results are expected in the spring of 1994.

"This will be beneficial for the next oil spill if there is one," said John Sandor, commissioner of the Alaska Department of Environmental Conservation, during a Wednesday press tour of Prince William Sound. Sandor kicked back a layer of mussels in a quiet bay on Disk Island to expose a thin layer of oil.

The Exxon Valdez ran aground on Bligh Reef on March 24, 1989, spilling more than 11 million gallons of North Slope crude oil in the Sound. Last year, the state and federal governments settled damage claims against Exxon for about $1 billion, with most of the money to be used for restoring the Sound and other spill-damaged areas.

Sandor said that, at the time of the spill, officials decided to leave the mussel beds alone, fearing disturbing the beds would do more harm than good. But last summer's discovery has caused them to reconsider.

Brodersen emphasized that only a small number of mussel beds are affected. Mussel beds formed on bedrock are not affected. Only mussel beds formed on fine soft, sandy sediment in the path of the oil were affected because the oil could collect under the beds. The oil sits right under the threads that anchor the mussels to the beach. The solid mass of mussel threads cut off oxygen to the oil and, without oxygen, the oil degrades slowly, if at all, Brodersen said.

Scientists don't know how long it will take the oil to degrade if left under the beds, Brodersen said, but added they were surprised to find "oil that smells like it was put there yesterday."

One of the experiments scientists are trying this summer involves stripping away 12-inch-wide swatches of mussels to see if enough oxygen can get to the oil layer to help it degrade, even under mussels left in place.

But it is a sensitive process, because, if too much of the bed is removed, there won't be enough threads in place for young mussels to connect to.

Another method being explored involves handling the mussels like a layer of turf, Brodersen said. If the oil is deep, the layer of mussels would be peeled back, the oil removed and the mussels replaced. If the oil layer is thin, the whole mussel layer would simply be flipped over, giving rain, air and storms an opportunity to break down the oil.

Though the connection between the tainted mussel beds and species higher in the food chain is still not clear, scientists know the oil leaches up out of the sediment into the mussels, Brodersen said.

They also know that harlequin ducks feed on mussels, shells and all; that mussels are a large portion of the black oystercatchers' diet; that mussels have been recovered from the feces of river otters; and that juvenile sea otters have nothing else to feed on during the winter months.

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