Whales reveal a toxic threat to Arctic food webs

The presence of algal toxins in bowhead whales, a key food source for Native Alaskan communities, points to a disturbing shift in the Arctic. As the Arctic Ocean warms, harmful algae are spreading and moving up the food chain.

A new study confirms what many in northern Alaska have long suspected: the marine life they depend on is changing in ways that threaten their health and food security.

Toxic threat to Arctic communities

Researchers from the Woods Hole Oceanographic Institution were part of a major, multi-institutional study on algal toxins in Arctic ecosystems.

The findings suggest that warming waters create ideal conditions for these toxins to spread. This threatens the clams, fish, whales, and other sea life that many subsistence-based communities depend on.

“These are new risks that were previously unknown,” said Kathi Lefebvre, a research scientist at NOAA Fisheries’ Northwest Fisheries Science Center, and lead author of the study.

“The people in remote communities in northern and western Alaska rely on marine resources for nutritional and cultural well-being. Now we’re finding that these resources are at risk.”

Recognizing the effects of warming

Many Native Alaskan communities – some of the most remote in the state – have been noticing these shifts for years.

Raphaela Stimmelmayr, a wildlife veterinarian with the North Slope Borough in Barrow, Alaska, is a co-author on the study.

“Native communities know intimately the ecosystems they rely on and were among the first to recognize the effects of warming,” said Stimmelmayr.

“It is very difficult to walk away from resources that they need and have relied on since time immemorial.”

Stimmelmayr emphasized the need for real-time field tests that can detect toxins in traditional foods before they are consumed.

Monitoring equipment and fast diagnostics would allow local communities to make informed choices about what’s safe to eat.

The life cycle of Arctic algae

Scientists at Woods Hole Oceanographic Institution, including Don Anderson, Bob Pickart, and graduate student Evie Fachon, have been tracking the movement and life cycle of the Arctic algae responsible for the rising toxic threat.

Their work sheds light on how warming waters are unlocking new threats from their hiding places in Arctic seafloor sediments.

“I have shifted a significant portion of my lab’s research focus to the Alaskan Arctic in recent years,” said Anderson. “It is a new frontier in HAB (harmful algal bloom) research, given the rapid warming of waters in the region and the massive scale of the Alexandrium populations we have documented.”

These populations, specifically the dinoflagellate Alexandrium, are known to produce potent neurotoxins.

Algae in the Alaskan Arctic

The problem is twofold: some blooms arrive from the south, drifting north with ocean currents, while others form locally when dormant cysts on the seafloor begin to germinate. That’s where the warming comes in.

“For years, these cysts have remained inactive, essentially preserved by the cold,” Anderson explained. “But as bottom water temperatures periodically warm, we see conditions that allow germination, and that changes the risk landscape dramatically.”

His team found that the world’s largest beds of Alexandrium cysts lie in sediments across the Alaskan Arctic. These build up when blooms from the Bering Sea drift north and settle in places like the Chukchi Sea.

For years, the icy seafloor kept them dormant. Now, rising temperatures are allowing them to activate and grow.

This local germination is creating a second, homegrown source of toxic algal blooms – intensifying the threat already posed by southern blooms. That dual pressure is putting more strain on marine life and the communities that depend on it.

Entire systems are shifting

Bob Pickart and his former postdoctoral researcher Peigen Lin studied how ocean circulation and water temperature are contributing to the problem of toxic Arctic algae. Their work shows a clear link between rising temperatures and the presence of toxins in bowhead whales.

“My Arctic research has become increasingly interdisciplinary over the years, including exploring the role of circulation patterns, atmospheric forcing, and water properties in HAB dynamics,” Pickart said.

In other words, this isn’t just about one algae or one animal. It’s about how entire systems – currents, climate, and biology – are shifting, with real-world consequences for the people living closest to the ocean.

Fighting Arctic algae with science

Experts at the Woods Hole Oceanographic Institution aren’t just observing these changes. They are actively involved in finding solutions.

Don Anderson also leads the U.S. National Office for Harmful Algal Blooms, which helps coordinate national strategies and responses to HABs. That includes research efforts, outreach, and communication with coastal communities across the country.

This isn’t a challenge with a quick fix. But with scientific insight and direct collaboration with Native Alaskan communities, there’s a growing push to better monitor, understand, and manage the risks of algal toxins in a warming Arctic.

The message is clear: warming oceans aren’t a future threat – they are already unleashing toxic risks in the Arctic that are reshaping what coastal populations can safely eat.

The full study was published in the journal Nature.

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