Algal toxins emerge as a new concern in Alaska’s Northern Bering Sea

For countless generations, people of the Bering Strait region have relied on the food they harvest from the sea without worrying about harmful algal blooms that threaten seafood eaters in warmer and more southern latitudes.

Now, as the Northern Bering Sea undergoes cascading effects of a warming climate, algal risks pose a new challenge.

And it has prompted a change in the way Nome youth grow up learning about collecting food from the waters around their home. In early April, Nome high school students traveled to Bethel with their science teacher, where they presented their research at the Western Alaska Interdisciplinary Science Conference held by Alaska Sea Grant.

Algal toxins were present, at very low but detectable levels, in fish they eat.

Sophomore Audrey Bruner-Alvanna was among the group of student researchers. She said young people are concerned about algal blooms, which proliferate in warmer conditions, and their potential effects on wild food resources.

“Because, you know, as the climate changes, as the world gets warmer and stuff, there’s going to be more of these toxins and stuff during summer,” she said. “I feel like a lot of people that I’ve talked to have been wondering about how our subsistence is going to change in the future based on all of that.”

The student research came about after one of the nation’s densest and biggest concentrations of toxin-producing Alexandrium algae ever documented burst forth in the waters of the Bering Strait region in 2022. 

Until the appearance of the “massive bloom, the most toxic bloom, the longest-persisting bloom in the U.S.,” local people barely knew what harmful algal blooms or Alexandrium are, said Emma Pate, president of the Nome Eskimo Community, the local tribal government.

“So we had to figure things out and learn really fast,” Pate said during an October “Strait Science” presentation hosted by the University of Alaska Fairbanks’ Nome campus.

That 2022 bloom followed prior years’ discoveries of Alexandrium toxins in clams and marine mammals, and it was followed by more discoveries and another big Alexandrium bloom. For local people, who harvest marine foods year-round, using sea ice as a platform in winter and open water after the ice melts in summer, the developments present new questions.

How far in the marine food web have the paralysis-causing algal toxins spread? How can people ensure that wild foods are safe? How can younger generations understand and manage something that used to be a non-issue but is now an environmental reality.Those high school students were enlisted to help find some answers. Pate, who was working at the time for the Nome-based tribal health provider Norton Sound Health Corporation, and Gay Sheffield, the Nome-based marine advisory agent for the Alaska Sea Grant program, recruited the students from Nome-Beltz High School. 

They led them in a crash course in 2023 on harmful algal blooms. The instruction included field work to learn how to sample water for algal contents.

The students followed up by descending on Nome’s frozen harbor with ice-fishing gear. They plucked out masses of tomcod, a species also known as saffron cod, that is a favored local food. They shipped off some of the tomcod to the Alaska Department of Environmental Conservation lab in Anchorage for testing; they cooked, shared and ate the rest.

The assumption was that no toxins would show up in tomcod swimming in the harbor in winter but that the exercise would be a good lesson in the scientific method, said Sarah Liben, the Nome-Beltz High science teacher helping to lead the project.

Results reported in early 2024 from the DEC lab were startling: Livers of the tomcod that Liben’s students caught held detectable levels of Alexandrium-produced saxitoxin and related gonyautoxin that also cause paralytic shellfish poisoning. Levels were far below anything that would pose dangers to people, but the presence itself was an important scientific discovery.

“When these results first came out, scientists were actually shocked,” Liben said.

Her students’ work continued. An ice-fishing expedition last December produced another round of fish tested at the DEC lab, this time in a different methodology that examined full body contents. The lab tests revealed no saxitoxin in the students’ tomcod, but they did show the presence of potentially poisonous gonyautoxin compounds, which are related to saxitoxin.

Scientists have already confirmed the potential for continued massive blooms of algal toxins in the Bering Strait region and farther north. On the sea floor, they have discovered some of the world’s biggest and most concentrated beds of dormant Alexandrium, the algae that produces saxitoxin and related toxins. Those Alexandrium cyst beds were once the dead end for algal cells that, for decades and even centuries, drifted north and sank. But now underwater temperatures are occasionally high enough to enable those cyst beds to bloom.

Don Anderson of the Woods Hole Oceanographic Institution, who has been leading research expeditions mapping the Bering, Chukchi and Beaufort sea cyst beds, describes them as a “sleeping giant” that are poised to erupt in massive blooms if temperatures get warm enough.

Anderson and Kathi Lefebvre, a Seattle-based National Oceanic and Atmospheric Administration research biologist, have devoted several years of study to the spread of harmful algal blooms in Alaska’s northern waters. Their work is part of a NOAA program called Ecology and Oceanography of Harmful Algal Blooms, or ECOHAB.