Seafaring scientists seek clues to toxin
Seattle Times staff reporter
Scientific name: Pseudo-nitzschia
Where it's found: Off the Northwest coast and, more rarely, in Washington's inland waters.
The dangers: Can be fatal to humans who eat shellfish contaminated with the toxin. Alga blooms have forced closure of clamming seasons.
ON BOARD THE RV MELVILLE — This 279-foot science ship is packed bow to stern with sophisticated instruments, but none sums up its mission better than a simple net slung over the side.
When the funnel of mesh is lifted from the water, researchers scan the contents under a microscope, looking for a needle-like plankton that packs a poisonous punch.
Last week, they discovered a 60-mile-long swath of the toxic alga off Washington's southern coast, where razor-clam season is set to open in mid-October. The alga's toxin, which can be fatal to humans, shut down clamming on Oregon's coast this spring and is blamed for hundreds of sea lion deaths off California.
For only the second time since monitoring began, dangerous levels of the toxin — called domoic acid — also turned up this month in Washington's inland waters, forcing shellfish closures in Sequim Bay.
From domoic acid on the West Coast to this year's record-breaking red tide on the East Coast, problems with toxic algae are increasing around the globe, and scientists are trying to figure out why. Pollution and global warming are suspects, but solid answers are few.
The Melville's cruise off Washington's coast this month is part of a five-year, $12 million effort funded largely by the National Science Foundation to better understand the alga that hits hardest in the Pacific Northwest: Pseudo-nitzschia (Soo-doe nitch-a), the source of domoic acid. The goal is to forecast outbreaks, called blooms, the way meteorologists forecast storms.
"We want to know what creates these things and how they get to the coast," said project leader Barbara Hickey, plotting the ship's course from her station in the middle of a laboratory bristling with beakers, pipettes and electronic equipment. With more than 35 years of seafaring experience, the University of Washington oceanographer takes no notice as her desk rocks up and down with the swell.
Last year, Hickey and her team found the largest and deadliest Pseudo-nitzschia bloom ever recorded: It was in the Juan de Fuca eddy, the roiling confluence of the Strait of Juan de Fuca and the Pacific Ocean. The 30-mile-wide vortex is rich in marine life and seems to be a permanent seed source for the toxic alga.
Currents and storms can sweep the alga to shore from the eddy, but the 2004 mega-bloom never hit the beaches.
This year, toxin levels in the eddy are low, said Vera Trainer, an oceanographer at the Northwest Fisheries Science Center in Seattle. The biggest hot spot is off Grays Harbor and Long Beach — possibly pushed north from another seed source off the Oregon coast.
Some of the toxin has already hit shore at Copalis and Long beaches, but so far levels in clams aren't high enough to close the popular season.
To predict where algae will go, it's crucial to understand weather and circulation patterns, Hickey said, watching as a crew member heaved overboard a blue cylinder fitted with orange sails like butterfly wings. The "floater" will drift, signaling its location and allowing scientists to chart currents and track the path of algae blooms. One floater traveled 100 miles down the coast in a week.
"Most people don't have any idea how fast things move in the ocean," Hickey said.
Under magnification in the ship's lab, Pseudo-nitzschia colonies look bland compared to other plankton with star-like shells or diatoms that cluster in balls. But their potency is impressive.
Domoic acid was first detected on the West Coast in 1991 after pelicans and cormorants began dying in California. That year, the toxin also appeared in Washington razor clams and the wildlife department set up roadblocks to turn back thousands of clam diggers.
Since then, the alga has shut down clamming several times, with each season-long closure costing local communities more than $12 million.
The $80 million Dungeness crab fishery is watching nervously. In 2003, crabbers were required to gut most of their catch because of high domoic-acid levels in the animals' digestive tracts, but not the meat.
The toxin concentrates in plankton-eaters such as clams, crabs and anchovies. When people ingest the toxin, symptoms range from vomiting to seizures. Only a handful of mild cases have been reported in Washington. But three people died and more than 100 were seriously sickened after eating mussels from Canada's Prince Edward Island in 1987. The illness is called amnesiac shellfish poisoning, because some victims permanently lose their short-term memory.
Clam diggers can't tell by sight or smell if their catch is safe, and the toxin isn't destroyed by cooking.
The trigger for razor-clam closures is 20 parts per million of domoic acid, but Duke University researchers said this month that may be too high to protect unborn children. Rats exposed to low levels of domoic acid in the womb showed lasting memory problems — even though their mothers never got sick.
From a starboard boom, the crew lowers into the water a metal cylinder the size of shark cage. At the center is a ring of tanks rigged to collect water samples at varying depths, all the way to the bottom.
Analyzing water chemistry will reveal the conditions necessary to brew up a noxious Pseudo-nitzschia stew.
Most toxic algae are like paralytic shellfish poisoning (PSP), often erroneously called red tide. Responsible for most of the clam and mussel contamination in Puget Sound, PSP algae always produce the toxin behind the bad reputation.
But Pseudo-nitzschia only churns out domoic acid some of the time, says marine ecologist William Cochlan of San Francisco State University.
The researchers found the toxin serves a vital function for the alga, allowing it to take up minute amounts of iron, which it needs to survive. Iron is in short supply in the Juan de Fuca eddy, which may explain why algae there always produce domoic acid.
But why do toxic blooms seem to be hitting Northwest beaches more often?
In a maze of tanks that crowd the ship's after-deck, Cochlan is testing the theory that sewage and other pollutants may be fostering a population boom. Runoff seems to be a factor in the spread of paralytic shellfish poisoning in Puget Sound, though the picture isn't simple. One of explorer George Vancouver's men died from PSP in 1793, and the algae also flourish in pristine Alaskan bays.
Another theory is that changing climate patterns may be pushing toxic blooms to shore more frequently, Hickey said.
The people of the Quinault Indian Nation have lived on the Washington coast for centuries, but elders don't remember any sickness caused by razor clams, said tribal fisheries spokesman Ed Johnstone.
Canned clams from the 1980s show low levels of the toxin. And some scientists speculate domoic acid may have caused a 1961 incident in Capitola, Calif., that was an inspiration for Alfred Hitchcock's "The Birds." Gull-like seabirds called sooty shearwaters smashed into windows, dive-bombed residents and staggered around vomiting chunks of anchovy.
With a research complement of about 35, the Melville's work spaces are so crowded that the scientists stagger their schedules around the clock. Some rise at 3 a.m. to take advantage of precious lab time.
"When the trip is over, people stumble off like zombies," Trainer said.
But she's already looking beyond this project, to development of buoys that could detect and track incoming algae blooms.
Advance warning would help clam diggers and coastal communities, said Washington Department of Fish and Wildlife shellfish biologist Dan Ayres.
Many longtime coastal residents remain skeptical that domoic acid is a real health threat, said Ayres, who also grew up in the area and never knew anyone who got sick from eating razor clams.
"But I've got two little girls at home," he said. "Do I want them to be the guinea pigs?"
Sandi Doughton: 206-464-2491 or firstname.lastname@example.org
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