DATE: Saturday, September 20, 1997          TAG: 9709200396

SECTION: LOCAL                   PAGE: B1   EDITION: NORTH CAROLINA 

SOURCE: BY LANE DEGREGORY and Scott Harper, Staff writers 

                                            LENGTH:   66 lines

DEAD CLAMS MYSTIFY RESEARCHERS

COROLLA - Thousands of dead or dying surf clams washed ashore on this northern Outer Banks beach this week, spread across a stretch of shoreline as long as 8 miles.

The clams first started showing up on Sunday and were tangled in mounds of starfish, said Corolla Fire and Rescue volunteer Tom Musika. They were concentrated in piles every 20 to 30 feet - with the densest groupings around the Corolla Light water tower and north of the road's end in Carova. The kill did not extend to the Virginia line.

By Friday afternoon, birds had eaten many of the clams, and other shellfish had washed back into the ocean.

But hundreds of the inch-long clams still were strewn along the sand.

State officials said they'd never heard of such a large amount of clams washing up along the ocean.

And opinions varied about what might have caused the kills.

On Wednesday and Thursday, fisheries experts collected tissue and water samples from the clams. Al Hodge, a water quality specialist with the North Carolina Department of Environment, Health and Natural Resources, said officials are checking to see if disease or a deadly microbe, Pfiesteria piscicida, might have been the culprit. The tests are ``just a precaution,'' Hodge said Friday - noting that the shellfish showed no lesions or other signs of a pfiesteria attack.

Another theory is that rough waters stirred up by Hurricane Erika along the Outer Banks might have killed the clams. Hugh Porter, curator of the wildlife collection at the University of North Carolina's Institute of Marine Sciences in Morehead City, said high waves churn up a lot of sand along the shore.

``If the clams get filled up with large amounts of sediment, they can't expel that,'' he said Friday.

``Clams are filter feeders. And they can't clean the sand out,'' Porter said. ``They get packed with sediment and can't survive.

``Surf clams normally burrow an inch or so into the sand below the ocean. If they start dying, they lose their ability to burrow. Then they end up on the surface of the sand and stand a greater chance of being washed ashore.''

Surf clams grow up to 6 inches across and live along the Atlantic from Nova Scotia through Cape Hatteras. Porter said he has heard of droves of the edible shellfish washing ashore along the New Jersey coast - ``especially after storms that have a lot of wave action.'' But the Corolla case is the first time he's heard of that happening in North Carolina.

``This probably is not a disease-caused phenomenon,'' he said. ``But you can never be sure.''

Pfiesteria, a one-celled predator, is suspected in the deaths of a billion fish in North Carolina and thousands of others in three waterways in Maryland and Virginia. Those kills all occurred in inland waters. The microorganism has not been found in its toxic form in the ocean.

Some citizens theorized that a ``red tide'' of toxic algae might have killed the clams. But the ocean off Corolla showed no discoloration Thursday, Hodge said. And he did not think a shock of pollution was to blame.

``Something came through here,'' Hodge said. ``There's no telling what it was.''

If the hurricane did cause the clam kill, Hodge wondered, why didn't more clams show up elsewhere on the Outer Banks? ILLUSTRATION: Color photo

DREW C. WILSON/The Virginian-Pilot

Vacationer Gene Glave of Isle of Palms, S.C., holds washed-up surf

clams Friday at Corolla. KEYWORDS: CLAM KILL OUTER BANKS

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