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The green monster 'blob' taking over California's oceans: Largest algae bloom ever seen is turning seafood toxic

Outbreak is the worst toxic algal bloom in more than a decade
Stretches from California's Central Coast to Washington
Toxin accumulates in shellfish and small fish such as anchovies

Published: 13:34 EST, 26 June 2015 | Updated: 15:06 EST, 26 June 2015

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A massive toxic bloom off the coast of California could grow to become the biggest of its type ever seen, researchers have warned.

The large blooms of toxin-producing algae in Monterey Bay, raising concerns about potential effects on marine mammals and seabirds.

The bloom, which researchers have nicknamed 'the blob', involves microscopic algae called Pseudo-nitzschia (a type of diatom), which produce a potent neurotoxin called domoic acid.

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Massive blooms of Pseudo-nitzschia, a type of single-celled algae, have been seen off the California coast. It can produce the neurotoxin domoic acid under certain conditions.

IS SEAFOOD SAFE TO EAT?

Periodic blooms of toxin-producing Pseudo-nitzschia diatoms have been documented for over 25 years in Monterey Bay and elsewhere along the U.S. west coast.

During large blooms, the toxin accumulates in shellfish and small fish such as anchovies and sardines that feed on algae, forcing the closure of some fisheries and poisoning marine mammals and birds that feed on contaminated fish.

All of Washington’s razor clamming beaches are currently closed, and the southern coast of Washington has the largest-ever closure of our state’s Dungeness crab fishery.

“The current bloom of Pseudo-nitzschia spp., the diatom responsible for domoic acid and amnesic shellfish poisoning, appears to be the biggest spatially we have ever observed,” Antony Odell of the University of Washington said.

“It has also lasted for an incredibly long time — months, instead of the usual week or two.”

It began earlier this year and shut down several shellfish fisheries along the West Coast

The toxin was first detected in early May, and by the end of the month researchers had detected some of the highest concentrations of domoic acid ever observed in Monterey Bay.

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.

'It's a pretty massive bloom,' said Raphael Kudela, professor of ocean sciences and Ida Benson Lynn Chair of Ocean Health at UC Santa Cruz.

'The domoic acid levels are extremely high right now in Monterey Bay, and the event is occurring as far north as Washington state.

'So it appears this will be one of the most toxic and spatially largest events we've had in at least a decade,'

Periodic blooms of toxin-producing Pseudo-nitzschia diatoms have been documented for over 25 years in Monterey Bay and elsewhere along the U.S. west coast.

Blooms such as the current event typically last for several weeks to a month. 'Often, if we have a big event in the spring, it will go away during the summer and come back in the autumn,' Kudela said.

'This event may be related to the unusually warm water conditions we've been having, and this year that warm water has spread all along the west coast, from Washington to southern California.'

Kudela's lab conducts weekly sampling of water and mussels at the Santa Cruz Wharf and works closely with the California Department of Public Health and other organizations.

Although Pseudo-nitzschia blooms often affect wildlife, careful monitoring and fishery closures ensure that commercial seafood remains safe to eat.

Raphael Kudela leads a team of researchers studying a large bloom of toxic algae along the west coast.

During the May 2015 event, researchers at the Monterey Bay Aquarium Research Institute (MBARI) measured concentrations of both Pseudo-nitzschia cells and domoic acid in the bay using robotic instruments called Environmental Sample Processors (ESPs), which are deployed on ocean moorings and can detect algal cells and toxins and send the results back to shore within an hour.

Complementing the data from the ESPs, Kudela's lab analyzed water and animals collected from the bay for Pseudo-nitzschia cells and domoic acid, and UCSC has two robotic gliders collecting data from the surface to a depth of 200 meters in the bay.

'We have confirmed domoic acid at very high levels in mussels and anchovy,' Kudela said.

His lab also found very high levels of the toxin in samples from a dead pelican found on the beach in Moss Landing, and testing of sea lion samples is under way.

'Domoic acid has clearly worked its way into the food web,' he said.

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Clarissa Anderson, who was a postdoctoral researcher in Kudela's lab and is now a research scientist with the UCSC Institute of Marine Sciences, has been leading the work on predictive modeling.

When the current domoic acid event began in Monterey Bay in May, the model was also predicting a bloom in coastal waters near Humboldt Bay in Northern California.

Anderson, who happened to be up there to give a talk, got local researchers to collect samples for testing, and Kudela's lab was able to confirm the presence of domoic acid.

'We're now developing a model specifically for the shellfish growers in Humboldt Bay,' Kudela said.

'We know users are paying attention to it.

'In addition to shellfish growers, the Marine Mammal Center is also using it to keep an eye on spatial patterns and whether toxin levels are going up or down, so they know where and when to expect strandings.'