West Coast toxic algae bloom prompts extensive study

An explosion of toxic algae along the West Coast has launched an expansive seagoing research project aimed at uncovering the roots of the growth, which contaminates shellfish and small fin fish with a poison that can kill the marine mammals, birds and people who eat them.

The current outbreak is the worst toxic algal bloom in more than a decade, stretching from California’s Central Coast to Washington, and possibly to Alaska, according to the National Oceanic and Atmospheric Administration. The algae is producing toxins in unprecedented amounts in some “hot spots” along the coast, officials say.

“Researchers in both the Monterey Bay and the Central Oregon Coast have found some of the highest concentrations of domoic acid that they’ve ever seen,” NOAA Fisheries spokesman Michael Milstein said.

Scientists are hoping that a three-month ocean expedition, launched Monday, to monitor and collect samples of the single-celled marine plants producing toxins along the West Coast will help answer why their numbers have skyrocketed.

Unlike the algal blooms that have plagued freshwater bodies like Clear Lake, the microscopic algae - also called phytoplankton - are not visible to the naked eye. But when their numbers are large, the water takes on a brownish-green hue. Some types turn the water a red color, leading to a common moniker for the outbreaks - “red tides.”

Domoic acid is one of several naturally occurring biotoxins that recur regularly with algal blooms and can accumulate in shellfish and small fin fish, like sardines. The neurotoxin causes a disease known as amnesic shellfish poisoning. Its symptoms include seizures, amnesia and even death.

Other forms of algal organisms produce paralytic shellfish poisoning, caused by the toxin saxitoxin, and diarrhetic shellfish poisoning, caused by the toxins okadaic acid and dinophysistoxins.

California health officials impose a quarantine on recreational mussel harvesting along the state’s entire coast annually from May 1 to Oct. 31 to help prevent people from becoming ill or dying from ingesting biotoxins. Since 1927, at least 542 people have been sickened and 39 have died from illnesses attributed to the toxins in California, according to state health officials.

Shellfish harvested by state-certified commercial fishing operations are tested regularly and considered safe.

With this year’s especially high levels of biotoxins, warnings have been extended to include shellfish that don’t accumulate toxins as quickly as mussels, as well as some fin fish. The state Department of Public Health is advising consumers not to eat either commercially or sport-caught anchovies or sardines or the internal organs of crabs and scallops from Monterey or Santa Cruz. Toxins accumulate in the organs of fish and shellfish. As a result, eating fish whole - as sardines typically are consumed - can be dangerous, health officials noted.

Aside from the regular mussel harvesting ban, no other closures currently affect the Sonoma and Mendocino coast.

In Oregon, officials have halted shellfish harvesting from the Columbia River south to Tillamook Head and closed the entire state coastline to razor clamming because of elevated levels of domoic acid. High levels of another toxin have shut down mussel harvesting along the Oregon Coast north of Gold Beach.

In Washington, all beaches have been closed to razor clamming, and both recreational and commercial Dungeness crab fisheries on the south coast were closed after testing showed high levels of domoic acid. It’s the first time the Washington crab fishery has been closed because of the toxin since 2003, state Fish and Wildlife officials said.

A number of factors are believed to be contributing to algal growth, including ocean upwelling that pushes nutrients to the surface and warmer water.

“There are unusually warm waters offshore. We think that, in some way, is helping these blooms along,” said Vera Trainer, manager of the Marine Microbes and Toxins Program at NOAA’s Northwest Fisheries Science Center in Seattle.

She said she believes toxic algal cells also are lurking offshore for longer periods of time, the likely result of fewer big storms that could wash them away.

But the exact cause of the larger-than-usual toxic algal outbreak remains undetermined, NOAA officials said.

“That’s what we’re trying to find out,” Milstein said of the research voyage.

You can reach Staff Writer Glenda Anderson at 462-6473 or glenda.anderson@pressdemocrat.com. On Twitter @MendoReporter.