The West Coast’s Massive Algal Bloom Could Be the Toxic Wave of the Future
Toxic algae are growing along the West Coast in greater quantities than ever, wreaking havoc on marine life and forcing the closure of Washington’s $20 million Dungeness crab fishery, along with mussel, clam, sardine, and anchovy fisheries in Oregon and California.
The massive algae bloom has been detected as far south as Santa Barbara, California, and as far north as Alaska, and it could continue to limit the seafood supply.
Ocean scientist Raphael Kudela and his team of researchers at the University of California, Santa Cruz, first identified the toxin, which they found accumulating off Monterey Bay, in early May.
“The domoic acid levels are extremely high right now,” Kudela said in an email. “It appears this will be one of the most toxic and spatially largest events we’ve had in at least a decade.”
As filter feeders, clams and mussels end up trapping high concentrations of the toxin in their digestive tract. Kudela recorded toxicity levels in shellfish and anchovies ranging from 95 ppm to 400 ppm. The legal limit for safe human consumption is 20 ppm for both.
Seafood goes through toxic level checks before it’s sold to consumers, and the local seafood on shelves today was either caught from areas unaffected by the bloom or before the bloom hit. But we could be seeing fewer crabs, clams, and mussels in grocery stores as closures go into effect.
So, Why Should You Care? The science behind algal blooms shows the chain reaction can lead all the way up the food chain and end up hurting sea life, our food supply, and possibly human health as well.
Voyaging for Answers
On Saturday, scientists from the National Oceanic and Atmospheric Administration will hop on board the agency’s research ship Bell M. Shimada in San Diego and set out to map the algae all the way to Alaska. They hope to determine what’s causing its spread.
The suspected culprit? Unusually warm offshore water temperatures, said Vera Trainer, manager of the Northwest Fisheries Science Center in Seattle.
“This is unprecedented in terms of the extent and magnitude of this harmful algal bloom and the warm water conditions we’re seeing offshore,” Trainer said. “Whether they’re related we can’t really say yet, but this survey gives us the opportunity to put these pieces together.”
All marine life is at the mercy of rising ocean temperatures as climate change accelerates. If hotter water creates better conditions for algae blooms to form, that could mean more frequent and severe toxic outbreaks could become the norm in coming decades.
NOAA spokesman Michael Milstein said it’s normal to have algal blooms in localized areas in the spring, but the last time such an extensive algal bloom was recorded was in 1998—the same year an El Niño weather event pushed warmer waters toward the coast.
“It’s difficult to say this event itself is related to climate change, but what we can say is that we would most likely see these types of water conditions as climate change progresses the way it’s currently projected to,” Milstein said.
The alga causing this bloom is called Pseudo-nitzschia. It produces a neurotoxin called domoic acid. Small fish such as sardines and anchovies eat the algae and nearby plankton, which accumulate the toxin. Those fish end up in the bellies of hungry sea lions and sea birds.
At high enough levels, the toxins can poison marine animals, leading to seizures and even death.
Milstein said only one sea lion in Washington has been recorded with signs of domoic acid poisoning so far.
“That doesn’t mean there aren’t numerous other sea lions and birds we don’t know about if they’re dying out at sea,” he said.
What’s With the Red Crabs?
While the bloom seems to have stayed north of Santa Barbara, another weird phenomenon has hit the Southern California Bight: red crabs.
Hundreds of thousands of tiny crustaceans, also known as tuna crabs, are washing up dead on beaches from the Mexican border up toward Los Angeles County.
Red crabs typically keep south off the coast of Baja California, but the crabs seem to have followed the “warm blob” of unseasonably high-temperature waters north to California’s coast.
But Kudela said the crabs’ northward death march was most likely the result of El Niño and shifting winds rather than domoic acid poisoning.
“The crabs accumulate the toxin but don’t seem to be particularly bothered by it,” he said.