Scientists on the trail of dreaded razor clam toxin

A satellite image shows the 30-mile-wide eddy that forms in the summer northwest of the Olympic Peninsula. Mixing cold, deep ocean water with effluent from the Strait of Juan de Fuca, the eddy is believed by scientists to act as a giant incubator for one-celled marine plants, including the algae species responsible for the domoic acid that closes clam seasons.

LONG BEACH - The satellite image is striking: An enormous plume of effluent swirls out of the Strait of Juan de Fuca where it mixes with the cold, nutrient-rich waters of the Pacific in a 30-mile-wide undersea caldron.

Many species of microscopic plants thrive within this eddy that forms inside a spur of the Juan de Fuca submarine canyon, among them the one-celled weed that produces domoic acid. And domoic acid, as most Washington razor clam-lovers know, is the marine poison that began periodically closing clam seasons starting in 1991.

In scientific terms, marine biologists believe this Juan de Fuca eddy may serve as the "bioreactor" for toxic phytoplankton blooms that have cost the coastal economy millions in lost clam and crab revenue in recent years.

"During the past decade the economic consequences of domoic acid on fisheries and ecosystem health have been severe along the U.S. west coast," according to a paper prepared by Vera Trainer of NOAA Northwest Fisheries Science Center and co-authors Rita A. Horner and Barbara M. Hickey, both in the School of Oceanography at  the University of Washington. "For example, off the Washington coast, closures of razor clam harvests have drastically impacted both coastal economics and traditional tribal harvests."

Now, an $8.7 million five-year study of this phenomenon is planned by ECOHAB PNW, which is short for Ecology and Oceanography of Harmful Algal Blooms-Pacific Northwest. Hickey is the overall science leader of this project, co-managed by Trainer. The study is funded by the National Oceanic and Atmospheric Administration (NOAA) and the National Science Foundation.

In addition to verifying scientists' theories about how this Juan de Fuca eddy functions, the study aims to design strategies for monitoring and predicting domoic acid outbreaks on the Washington coast from Long Beach north to the Makah Indian Reservation.

Little-studied eddy about to get lots of attention

The eddy forms in the spring and dies back in the fall just west of the 17-mile-wide mouth of the Strait of Juan de Fuca, in the Pacific west of the Olympic Peninsula and south of Vancouver Island.

During those months, waters from Puget Sound and the Strait of Georgia mostly flow west out into the ocean. There they begin to swirl in a counterclockwise direction, forming a spinning gyre in which this submarine river and tidal forces combine to churn up deep, nutrient-rich ocean waters and bring them to the surface.

Nutrient-rich waters also reach the surface in a narrow zone close to the coastline, and scientists haven't ruled out the possibility that domoic acid impacting Long Beach and other beaches to our north might be locally produced. But evidence points to the eddy as being a giant incubator that turns its algae loose on the coast following specific fall storm conditions.

Instruments set adrift in this eddy show materials circle within it for about a week and then tend to be ejected from the eddy's southeast quadrant toward the Washington coast. This was expensively demonstrated in July 1991 when a tanker sank in the eddy, resulting in oil washing up on the Washington coast six days later.

The eddy hasn't been intensively studied, but sampling so far shows its waters are extremely hospitable for the one-celled plants that are the foundation of the ocean food chain. Early in the warm season, there can be nearly 4 million of these diatoms per gallon of sea water.

The trouble-making species that sometimes, but not always, produces domoic acid is only a small part of this great swirling stew of plant life - maybe 10 percent of the total. Similar concentrations of this diatom, with the intimidating but poetic name Pseudo-nitzschia pseudodelicatissima, have caused major toxic effects among sea lions in Monterey Bay on the California coast. And when scientists have had occasional chances to collect samples inside the eddy in the past few years, they've found much higher concentrations of domoic acid suspended in the water than elsewhere on the Washington coast.

Domoic acid: An unpleasant surprise starting in 1991

Domoic acid exploded into the consciousness of coastal residents on Nov. 11, 1991, when the Washington State Department of Fisheries abruptly canceled the remainder of the fall razor clam season after random tests found high levels of the toxin here. Then, on Dec. 10, Washington and Oregon closed the commercial Dungeness crab season after finding excessive levels of domoic acid in crab intestines.

These closures followed a Sept. 6, 1991, incident when the California Department of Fish and Game learned of sick and dying brown pelicans and cormorants in the Santa Cruz area.   Then described as "a relatively new and relatively rare" substance that was believed to have washed ashore in brown algae, the toxin was never conclusively linked to human illnesses here. There was great public outcry over loss of recreation opportunities, tourist dollars and fishing revenues.

Almost no one had heard of domoic acid, which first came to the attention of North American health officials in 1987 when mussels commercially raised off Prince Edward Island in eastern Canada caused four deaths and 107 cases of Amnesiac Shellfish Poisoning, or ASP.

Mild cases of ASP result in flu-like symptoms including nausea, cramps, diarrhea and vomiting. More severe poisoning can cause death, coma or extensive neurological problems including a permanent loss of ability to form short-term memories, reminiscent of the popular 2001 movie "Memento," in which a man must tattoo himself in order to remember clues to his wife's murder.

In 1998, another period of high domoic acid levels again closed razor clam seasons for an entire year, at an estimated cost of $12 million in lost recreation spending and $7 million from the tribal commercial harvest. Fisheries including crabbing are the largest employer in Washington coastal communities.

Even when domoic levels are below the 20 parts per million threshold at which the Washington State Department of Health closes beaches to harvest, it has an impact on planning sport seasons, since it often isn't known until the last moment when clamming will be permitted to proceed. Improved forecasting of toxic algal blooms would help alleviate this problem.

Scientists in two nations will devote years to study

All this led to formation of the Olympic Region Harmful Algal Bloom Partnership, led by Dr. Trainer of the Northwest Fisheries Science Center, and supported by UW, coastal tribes, state agencies, the Olympic Coast National Marine Sanctuary and several scientific institutions. It is funded by NOAA through the National Center for Coastal Ocean Science.

Its mission is investigating marine toxins and developing ways to forecast them. Ultimately, there even is some hope of developing ways of intervening as algal blooms occur to stop harmful levels of domoic acid from forming.

Since 1998, ECOHAB PNW has spent about $1.6 million on three studies on aspects of the domoic problem, and this summer it lined up funds for an $8.7 million, five-year program that will attempt to answer a variety of questions.

"This study was the result of cruises with the Olympic Coast National Marine Sanctuary and a collaboration that was initiated through the [ORHAB] partnership," said Trainer. "Now we can plan research cruises to carefully study the dynamics of  this type of harmful algal bloom knowing that the Juan de Fuca eddy is a  likely place for us to find toxic Pseudo-nitzschia."

Researchers from UW, the Northwest Fisheries Science Center, and universities in Maine, California and Canada will study the eddy and its life forms during six three-week cruises, during which instruments will be deployed on drifters and moored buoys.

Scientists hope to learn exactly what makes the eddy so hospitable for toxic algae, what causes the production and release of domoic acid, and how that acid is transported from the eddy to shellfish beds.

The research ship will be equipped to conduct on-deck incubation studies and to capture detailed measurements of what's going on in the sea. One important question they will seek to answer is how minute amounts of iron and copper in the sea water contribute to algal growth.

Recommended for you

(0) comments

Welcome to the discussion.

Keep it Clean. Please avoid obscene, vulgar, lewd, racist or sexually-oriented language.
PLEASE TURN OFF YOUR CAPS LOCK.
Don't Threaten. Threats of harming another person will not be tolerated.
Be Truthful. Don't knowingly lie about anyone or anything.
Be Nice. No racism, sexism or any sort of -ism that is degrading to another person.
Be Proactive. Use the 'Report' link on each comment to let us know of abusive posts.
Share with Us. We'd love to hear eyewitness accounts, the history behind an article.