There’s a Toxic, California-Sized Algae Bed Creeping Into the Arctic

Scientists say the size of the algae cyst bed is “unprecedented globally” and threatening the Arctic food supply.
Kotzebue algae bloom
A bloom of cyanobacteria, a different toxic algae, on the water near Kotzebue. A. catenella is largely invisible. Photo courtesy of Alex Whiting
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Scientists have discovered what they believe to be the world’s largest toxic algae cyst bednearly the size of California—off the coast of Alaska.

“It’s astounding,” said Don Anderson, a senior scientist at the Woods Hole Oceanographic Institution and the lead researcher on the project that documented the massive bed—more than 1,000 kilometers (600 miles) long and 350 kilometers (200 miles) wide in the Chukchi and Beaufort Seas. “It dwarfs anything I’ve ever seen anywhere.”


Researchers worry a toxic bloom, produced by the cysts of the algae species Alexandrium catenella, could lead to mass die-offs of marine species, and imperil the food supply of dozens of remote Arctic communities—or even cause sickness and death in humans.

While oral histories in the region include stories of deaths in the wake of a “red tide” like those sometimes caused by A. catenella, it’s the first time the cysts that produce the blooms have been documented north of the Bering Strait in such large quantities and over such a large area. 

A water sampler deployed from the research vessel Sikuliaq during Anderson's 2020 expedition to the Arctic.

A water sampler deployed from the research vessel Sikuliaq during Anderson's 2020 expedition to the Arctic. Photo by Woods Hole Oceanographic Institution

Scientists believe waters warmed several degrees by climate change now provide the conditions necessary for it to grow and reproduce in massive blooms.

“The sleeping giant isn’t sleeping. It’s awake,” Anderson said.

A. catenella is among the world’s “most dangerous and widespread” toxic algae species, Anderson’s paper explains. It is behind the mass poisoning of shellfish in the Gulf of Maine, and the red tides that shut down Pacific shores, causing an estimated $82 million in economic losses.

A. catenella cysts can lie dormant on the ocean floor for decades at a time, growing exponentially when the temperature conditions are right to produce massive blooms. Those blooms can be toxic even when they are invisible to the naked eye.


In the process, they produce a poison called saxitoxin that is absorbed by shellfish. When the shellfish are eaten by humans, it can produce “symptoms ranging from tingling lips, to respiratory distress, to death”—what is called “paralytic shellfish poisoning.”

But recent evidence presented by Steve Kilber, an oceanographer with the U.S. National Oceanic and Atmospheric Administration, shows those toxins also accumulate in other species, making their way—eventually—onto the dinner table.

In Kotzebue, Alaska, a remote community of 3,000 people not far from the center of the discovery, as much as 70 per cent of the local food supply is directly harvested from the water. Fish and seabirds are at the core of the local diet, and seal oil is a “daily condiment.”

“You can’t really overstate the importance of Kotzebue Sound… as a means of support to both commercial fishing and the subsistence economy,” said Alex Whiting, a local monitor who manages environmental programs in the community. “It’s a major part of defining who the people are.”

Whiting says he’s noticed “a lot more dead seabirds washing up around the [Kotzebue] Sound” since the bloom was first observed in 2019.

Though there have still been no documented incidents of poisoning in Alaska, Anderson said the bloom could cause “mass mortalities” in the food chain. He said the discovery represents “a serious and growing threat” to the food supply in Arctic communities.


Caroline Behe, the Indigenous knowledge and science advisor for the Inuit Circumpolar Council (ICC) in Alaska, said if the water became toxic, it would endanger not only food security in the traditional sense, but the security of local Inuit traditions and values that have survived for centuries.

“What [food security] means starts to be about a lot more than nutrients and calories,” she said.

Behe says if toxic algae blooms are going to become a reality in the Alaskan Arctic and beyond, forecasting and communicating risk will be essential to preventing serious health impacts.

“Before these large events happen, we need to work at having true co-management… with Indigenous people,” she said. “It’s really important we’re taking guidance from the community, because they know what’s happening.”

The Arctic cyst bed, Anderson’s research shows, “is the densest and geographically largest known feature of its type globally”—15 times more dense and six times larger than any yet recorded. The bed continues into Russian waters where it has still not been mapped.

“We know it goes further, but we don’t know how far,” Anderson told VICE News.

A map from Anderson's study showing the extent and concentration of toxic A. catenella cysts in the Chukchi and Beaufort seas.

A map from Anderson's study showing the extent and concentration of toxic A. catenella cysts in the Chukchi and Beaufort seas.

There is some reason for optimism. In 2009, Kotzebue residents were alarmed by the appearance of a massive algae bloom in the waters near the community.

“It looked like a paint spill, like someone had dumped a whole oil tanker full of chartreuse paint in the water,” said Whiting.


Since then, local monitors and researchers have set up networks to track the impact of harmful algae on the ecosystem. Those networks are now “only… more useful,” Whiting said.

The nature of research on these issues is changing, too. The ICC is about to release new guidelines for community-based research, and Anderson is meeting virtually with local leaders and monitors to discuss how to get the word out to community members. (A planned community tour was scheduled for this year, but delayed by COVID-19.)

Alex Whiting takes a water sample off the coast of Kotzebue, Alaska.

Alex Whiting takes a water sample off the coast of Kotzebue, Alaska. Photo courtesy of Whiting

But there is still more to be learned. Whiting is increasingly concerned by other harmful species, like cyanobacteria, which are blooming at shorelines near Kotzebue more frequently amid rising temperatures. Their potential toxic impact is less well understood.

Along with his colleagues, he’ll be keeping a close eye out for impacts on the food chain.

“We’re a major consumer of those species they’re finding toxins in,” he said. “We take hundreds of marine mammals a year… How are we to know if at some point those levels become unsafe?”

John Last is a freelance reporter covering Europe and the Arctic. Follow him on Twitter.

Correction, Oct. 8: A previous version misstated the name of the Woods Hole Oceanographic Institution.