An enormous algal bloom containing domoic acid, a potentially fatal neurotoxin that shut down dungeness crab and razor clam fisheries in Washington state this summer, has spread to Alaska waters. But dozens of shellfish samples taken since the bloom appear to contain only trace amounts of the substance, state scientists said this week.
Shellfish that consume the algae appear to be unharmed by domoic acid, but in high enough concentrations the toxin causes a host of health problems in the mammals that eat them. In 1987, at least 107 people who bought contaminated mussels from Prince Edward Island in Canada reported a variety of symptoms including vomiting, headaches, diarrhea and, in many cases, permanent short-term memory loss. Three of them, aged 71 and older, died.
In Alaska, the testing process for domoic acid begins in a briny-smelling preparation room at the Department of Environmental Conservation's environmental health laboratory in Anchorage.
One morning in August, as sunlight poured through a plate glass window, lab technician John Cable used an enormous blender to turn geoduck and oyster meat into a shellfish smoothie of sorts. After pouring batches of the tan-colored liquid into glass beakers, he added hydrochloric acid before boiling each container on small hot plates.
"We're mimicking the human stomach, which uses acid and heat to break down the tissue further, to help release toxins," said laboratory chief Patryce McKinney.
Cable would then pour the hot, acidic mixture carefully into large plastic tubes and separate liquid from solid by spinning the tubes in a centrifuge. The liquid would be sent to two labs. In the biology lab it would be injected into white mice as part of the state's routine testing for paralytic shellfish poison. The chemistry lab would use it to test for domoic acid.
The state lab's domoic acid surveys, begun in June, focus on commercially farmed oysters, blue mussels, razor clams and geoducks from Southeast and Southcentral Alaska, regions where the giant bloom has appeared and commercial shellfish farms are located. The laboratory has also tested sand lance and dungeness crab in the Aleutians.
"We're keeping an eye on it, but we haven't found it," McKinney said.
The bloom, stretching from Southern California to Alaska, is made up of pseudo-nitzschia, a type of algae (or phytoplankton) commonly consumed by shellfish and other marine species.
The phytoplankton does not always produce levels of domoic acid that are dangerous to mammals. When it will do so is not always predictable, said Bruce Wright, Anchorage-based senior scientist for the Aleutians Pribilof Islands Association.
"Sometimes the blooms don't manufacture the toxin," said Wright, who was lead scientist for the National Oceanic and Atmospheric Administration following the Exxon Valdez oil spill. "We have a ton of questions about where this stuff is and how toxic it is."
Calm, warm seas appear to help set the stage for the blooms and the production of domoic acid, which is one reason that a large "blob" of warmer-than-normal water in the North and east Pacific Ocean is worrisome, Wright said.
Testing domoic acid levels in shellfish by placing samples into a $350,000 piece of equipment that generates readings onto the screen of a neighboring laptop is the job of Jackie Knue, the chemistry section supervisor at DEC's lab. Of more than 50 samples tested this summer, the lab has only found amounts far below the legal limit for human consumption.
"We want to not impact the industry, but if we had a positive result showing levels at about (the legal limit of) 20 parts per million, Jackie would come running to me like a chicken with its head cut off and I'd get on the phone with my boss right away," McKinney said.
The DEC has the authority to halt sales and issue recalls of commercial products for health and safety reasons, while the Department of Fish and Game could shut down subsistence, personal use, recreational and commercial fisheries should domoic acid or other toxins become real threats.
Beyond the state lab, others also have started testing for domoic acid.
A large bloom of pseudo-nitzschia in Kachemak Bay two weeks ago prompted researchers from the National Oceanic and Atmospheric Administration to gather some mussels and perform a field test, something the federal agency does not normally do, said Dominic Hondolero, an oceanographer with NOAA.
The test showed less than 5 parts per million of domoic acid.
"We weren't worried about it," Hondolero said. He noted that pseudo-nitzschia in the bay has declined again to normal levels for this time of year.
Margo Reveil, president of the Alaska Shellfish Growers Association, said she does not foresee the algae turning toxic. For Alaska's small shellfish farming industry, that could be devastating, as peak harvests occur in July and August.
"We're seeing the algae in the water and keeping a very close eye on it," said Reveil. "We want healthy products to enter the market, but we're not seeing it becoming toxic and we're not expecting it to."
Meanwhile, the state environmental health lab is working on the results from this week's samples, which will take close to one month to complete, McKinney said.
"From the regulatory point of view, we absolutely don't want to see it," McKinney said. "But from the scientific perspective it would be interesting."