A long band of toxic algae blooming off the West Coast of the United States shows no sign of receding months after scientists first observed it, leaving many worried that it will make trouble for local commercial fishing and tourism industries.
Some species of algae in the bloom—part of a group called called Pseudo-nitzschia, produce a toxin known as domoic acid, which can harm or even kill seabirds, mammals and humans. There's still a lot about the algae bloom that scientists don't understand—but some of what they have learned has them concerned.
Among their concerns is the possibility that an unusually strong El Nino climate pattern—such as the one that's expected this year—will keep water temperatures in the Pacific Ocean unusually high through next year, meaning the toxic bloom could last through 2016, said Raphael Kudela, a professor of ocean ecology at the University of California Santa Cruz.
"The one that we are waiting to see is one of the strongest El Ninos ever, and those are exactly the sorts of conditions we have been having so far," Kudela said. "So we are waiting to see if next year we will have a big bloom, and that would be pretty much unprecedented to have blooms two years in a row."
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The size of the bloom and the amount of time it has lasted in the ocean are already unprecedented, according to the U.S. National Oceanic and Atmospheric Administration. It stretches across much of the West Coast of North America, from Monterey Bay off the central coast of California all the way up to the Aleutian Islands in the southern region of Alaska.
Scientists had previously believed that domoic acid was water soluble—meaning that it could be flushed out of the bodies of animals that ingested it, Kudela said.
But researchers have since observed domoic acid building up in the tissues of fish, leading scientists to doubt that notion. They also think that the toxin may be spreading to a wider array of marine life than they had previously thought was possible.
"That really suggests that it is really going to work its way through the food web," Kudela told CNBC. "It has always been assumed cleaning the fish (meant that) you'll be fine, as long as you are removing all of the viscera. Now, we are questioning that."
State health departments in California, Oregon and Washington have all issued warnings against catching or eating shellfish and plankton-eating fish such as sardines and anchovies from areas off the coast.
Store-bought seafood should still be safe to eat, said Vera Trainer, manager of the marine biotoxin program at NOAA's Northwest Fisheries Science Center, since it is regulated and sourced from unaffected areas. The primary danger to humans so far still comes from eating fish caught recreationally.
Plankton is a major food source for many varieties of small fish and shellfish. Seabirds, larger fish and even mammals accumulate the toxin when they eat shellfish or small plankton-eating fish, such as anchovies and sardines.
The Food and Drug Administration has determined that domoic acid levels below 20 parts per million in shellfish tissue are safe. But at higher levels, the toxin can cause nausea and vomiting, or even memory loss and, if doses are high enough, death.
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State fish and wildlife management agencies have closed off fisheries affected by the bloom—already resulting in millions of dollars of lost revenue to local economies.
Washington state closed its Dungeness crab fishery along its southern coast earlier this year, resulting in lost revenue for the state's multimillion-dollar crab fishing industry. It was the fishery's largest closure in history.
Washington's crabbing industry is worth about $84 million annually, according to NOAA. That number does not include revenue from canning, transportation, retail and the other industries that serve crab fishing.
The annual commercial crab fishing season starts in December, and officials such as Dan Ayres, a coastal shellfish lead biologist with the Washington Department of Fish and Wildlife, fear they may have to delay the season, or cancel it altogether. "We are still contemplating a closure," he told CNBC.
Crabs are not the only market that could be affected. A study from 2009 conducted by NOAA and the University of Washington estimated that a yearlong ban on recreational razor clam digging in the state would result in a $22 million loss to local tourism and other industries.
Those losses could persist over the next few years. Razor clams are an especially fatty variety of clam, and they store the toxin in their fat. At around this time of year, they begin building up fat reserves to last them through the winter and the springtime spawning season. Thus, unlike many other varieties of clam, razor clams will hold onto high levels of the toxin for a year, or more, Ayres said.
If the bloom sticks around in 2016, razor clam digging seasons may be closed through much of 2017 or beyond.
To make matters worse, razor clams are a popular food source for Dungeness crabs, meaning high domoic acid levels could persist in crabs for at least another year.
Ayres said that if ocean waters remain warm in future years—the effects could be severe and impact the whole ocean food web.
"Warmer weather makes things grow faster, and Pseudo-nitzschia are adapting well to the change," he said.