Mass die-off of marine life predicted from powerful red tide along California's central coast

A health warning is urging people not to eat anchovy, sardines, crab, or shellfish from the Monterey Bay

    

Scientists with the Monterey Bay National Marine Sanctuary are predicting a mass die-off on the Central Coast because of a powerful red tide.

Researchers are seeing the highest levels of red tide in more than a decade, and they're worried it will have grave impacts on marine life.

"This is probably the largest domoic acid event they've seen in the last decade, so it is pretty severe," said Scott Kathey of the Monterey Bay National Marine Sanctuary.

Up and down the West Coast, a large algal bloom of Pseudo-nitzschia is growing rapidly. As it gets bigger, it's producing more and more domoic acid, known to most people as red tide. The acid closes shellfish harvesting and can kill some animals.

The National Oceanic and Atmospheric Administration reported in early May that particulate domoic acid levels were exceeding 30 micrograms per liter of seawater. Shellfish harvesting closures are implemented when domoic acid levels reach 20 micrograms per gram of shellfish tissue. The bloom has continued to grow since then.

Researcher Raphael Kudela of the University of California Santa Cruz said the tide hasn't been this potent since 2000.

Red tides are not uncommon in the Monterey Bay, but when it is strong like this one, the concern is for marine life as concentrations of the acid move up the food chain.

"By the time you get to the higher level predators, like a sea lion, it's already been concentrated through all these fish on the ladder to the sea lion," said Kathey. "The visible aspects will be, like, the shakes, their behavior becomes very erratic. They can't focus on feeding, so they get dehydrated, malnourished, and then they essentially starve to death."

In past decades when there have been strong red tide events like the current one, there have been mass die-offs.

"It's sad to see, because you can tell they are in distress, and there is not much we can do about it," Kathey said.

The California Department of Fish and Wildlife is already reporting effects from the high domoic acid levels. Melissa Miller, Ph.D, with the department said Kudela and a team at UCSC have determined a mass die off of anchovies along the Monterey Bay is related to the bloom.

Miller, who studies marine organisms, said she was asked to collect a dead pelican in Moss Landing to see if domoic acid was a factor in its death.

"I can't look at animal, and say, 'Yes, it tested positive from domoic acid,'" she said about the post mordum process.

Kathey said if you see a marine mammal suffering, you can call the Marine Mammal Center in Moss Landing.