'Mystery' marine toxin closes shellfish beds near Port Townsend

A mysterious marine toxin previously found only at trace levels in Washington's inland waters has been discovered at a concentration high enough to force closure of shellfish beds.

The appearance of domoic acid in mussels near Port Townsend alarmed shellfish growers who tend the state's $75 million-a-year shellfish harvest and sent scientists scurrying to investigate. It's the same toxin that has shut down razor-clam digging on the Pacific Coast three times since the early 1990s.

The find near Port Townsend is significant because it's a first for Washington's inland waters, although state officials emphasized that shellfish sold in stores have been thoroughly checked and are safe.

"Domoic acid is unheard of in our commercial shellfish species," said Robin Downey, executive director of the Pacific Coast Shellfish Growers Association. "It's disturbing."

The cause of domoic acid outbreaks remains unclear. It's one of a number of toxins that are produced by microscopic marine organisms. And the incidence of at least one organism, which causes paralytic shellfish poisoning, seems to be increasing in Puget Sound -- perhaps because of increasing population around the Sound and its attendant pollution, scientists say.

The phenomenon also appears to be on the upswing elsewhere in the nation.

However, it's also clear that these so-called "harmful algal blooms" have been around in some form for thousands of years. Even the Old Testament spoke of what later became known as a "red tide" because the profusion of algae in such an outbreak gives the water a brownish-red cast.

A member of British explorer George Vancouver's crew died in 1793 in British Columbia after eating shellfish contaminated by microscopic organism that causes paralytic shellfish poisoning.

But measurements of domoic acid are fairly new. It first came to health authorities' attention in 1987, when three people died and 107 others got sick after eating mussels at Prince Edward Island in eastern Canada.

Then it came to light on the West Coast in 1991, when cormorants and pelicans in California's Monterey Bay died or showed signs of poisoning by domoic acid. That was the same year scientists found domoic acid in razor clams and Dungeness crab on the Washington coast. Seven years later, domoic acid caused seizures that proved fatal for about 50 sea lions in Monterey Bay.

Scientists trying to unravel the mystery were able to determine that domoic acid has been around for some time. Razor clams frozen in the 1980s contained the toxin, researchers later discovered.

And remember Alfred Hitchcock's thriller "The Birds"? That 1963 movie's depiction of flocks of birds going crazy and attacking residents of a California coastal town was based on an incident in which birds that ate sea life -- now thought to have been contaminated by domoic acid -- crashed through windows and attacked townspeople in Capitola, Calif.

What's causing domoic acid to appear in Washington's inland waters now is the subject of intense investigation.

So far, only one commercial shellfish grower has been affected, although large portions of the eastern Jefferson County coast already were closed because of paralytic shellfish poisoning.

It just so happened that when Washington Department of Health officials got test results last Thursday showing a spike in domoic acid levels near Port Townsend, a research ship was checking out domoic acid on the coast. (State authorities announced yesterday that the domoic acid levels on the coast have dropped and a razor-clam season is tentatively scheduled for Sept. 26-28.)

The researchers on the ship, paid for by the National Science Foundation and the National Oceanic and Atmospheric Administration, decided to check into the outbreaks in the Port Townsend area on their way back. They were taking more samples yesterday, said Barbara Hickey, a University of Washington oceanographer directing the research project.

"Our team is really trying to understand the conditions that lead to these blooms," Hickey said.

Vera Trainer, co-director of the research project, said scientists are working on the hypothesis that the tiny plants known as diatoms that produce the domoic acid are putting out the toxin and then re-collecting it to absorb iron from the water. Plants need iron for photosynthesis.

"People are asking, 'Is it pollution?' All I can say is these algae are found in their toxic form in relatively pristine waters," Trainer said.

However, it's possible that pollution levels could influence the severity or incidence of the toxic algae blooms, she said. Scientists expected to return to Seattle today from the research cruise, for example, are interested in whether dumping of raw sewage off Victoria could have an effect.

"You can't rule that out as a contributing factor," Trainer said.

In a strange way, scientists on the research cruise that ends today were happy to hear about the outbreaks around Port Townsend.

"This is one of the first opportunities where we can go into the field and see if what we found in the lab holds," Trainer said.

DOMOIC ACID FACTS

Q: What is domoic acid?

A: It's a toxin produced by microscopic marine algae that accumulate in shellfish and, in high enough doses, can poison people who eat the clams, oysters, mussels and scallops.

Q: What are the symptoms of poisoning?

A: Usually just a stomachache, cramping and possibly diarrhea. In more severe cases, neurological damage can cause dizziness, confusion, disorientation, permanent loss of short-term memory, weakness, seizures, respiratory secretions, a disturbed heartbeat and coma. In very high doses, it can cause death.

Q: Does cooking shellfish make it safe to eat?

A: No. Neither does freezing it.

Q: What causes the outbreaks?

A: No one is sure. Scientists are trying to find out what conditions spark them. They have occurred in pristine waters; scientists want to know whether the incidence is increasing, as it seems to be, and if so whether pollution may have an effect.

Sources: Washington Department of Health; Washington Department of Fish and Wildlife; University of Washington; National Marine Fisheries Service.

P-I reporter Robert McClure can be reached at 206-448-8092 or robertmcclure@seattlepi.com

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