SEATTLE - A toxic algae bloom 30 miles wide has been detected 15 miles off the northwest coast of Washington state, the largest and most potentially lethal yet found by scientists in the region.
Pseudo-nitzschia algae in the Juan de Fuca eddy can release potentially deadly domoic acid, which accumulates in the tissue of razor clams and other shellfish and, if ingested by humans, attacks areas in the brain responsible for learning and memory.
Concentrations of the poisonous algae are as high as 11 million cells per liter, compared with about 200,000 cells per liter last year, scientists said Tuesday following a three-week research mission. A liter is slightly larger than a quart.
"Within the next week, if there's a major storm, it's possible it might hit the beach," said Barbara Hickey, a University of Washington oceanographer.
On the other hand, fair weather over the next couple of weeks could reduce the bloom and help keep it from approaching land, Hickey said.
State officials test coastal waters twice a week for the presence of domoic acid, and satellites are being used to track the algae bloom and detect any move toward the coast, scientists said.
"We'll have enough early warning to know for sure that the (shellfish) resource is safe to dig," said Vera Trainer, a research oceanographer with the Northwest Fisheries Science Center.
A second project, the Olympic Regional Harmful Algal Bloom, also is tracking algae off the Washington coast from Makah Bay at the northern tip of the peninsula to Long Beach, near the mouth of the Columbia River.
"That program, in collaboration with ECOHAB, gives us a comprehensive picture," Trainer said. "We're depending on ORHAB to tell us whether this bloom is going to hit the coast." Hickey said her team in the $12 million project, ECOHAB Pacific Northwest, benefited from an unprecedented opportunity to study the conditions that produce massive algae blooms.
There have been occasional "red tides," blooms of colorful but harmful algae, along the coast for centuries, but for unknown reasons poisoning from domoic acid became a significant problem only starting in the late 1980s.
Harmful algae blooms have increased in number and intensity in recent years but generally have been about a couple of miles wide outside the Strait of Juan de Fuca, which links Puget Sound and other inland marine waters with the Pacific Ocean.
Hickey said the current bloom may be so huge because of unusually cool, rainy weather since late August.
Scientists believe Pseudo-nitzschia, of which there are about eight species, not all of them toxic, is fed by nutrients from deep in the ocean or carried outward into the eddy by currents through the strait between Vancouver Island and Washington's Olympic Peninsula.
"Basically, it's sort of a crock pot, stewing and retaining the cells and the toxins," Trainer said.
