Rapid Arctic warming sets the stage for dangerous algae blooms

Toxic algal blooms are on the rise, even in the frigid waters of the Arctic, according to a new study published in the journal Proceedings of the National Academy of the Sciences. 

An international group of researchers from the National Oceanic and Atmospheric Administration (NOAA), the Woods Hole Oceanographic Institution (WHOI), and other institutions took samples from the very top and the very bottom of the water column from across the seas surrounding Alaska. The depth of the samples as well as their geographic range allowed the researchers to study the algal genus Alexandrium, in particular. 

Alexandrium begins its life as a “seed” on the ocean floor, rising through the water column as it matures. Though microscopic algae is a normal part of the marine ecosystem, when conditions are right they can “bloom” – rapidly multiplying and dispersing. The toxic blooms can lead to widespread health impacts for both wildlife and people, and can even be fatal. 

“We’ve known about human and marine wildlife health risks associated with Alexandrium and its toxins in Alaskan waters for a long time, including occasional events north of Bering Strait, but these results show increased potential for large and recurrent blooms of this species as a new hazard for Alaska’s Arctic,” said WHOI senior scientist Don Anderson.

“The rapid warming that we’re seeing all across the Arctic is setting the stage for dangerous bloom events in the waters of western and northern Alaska that we formerly thought were too cold for significant germination and growth.”

The decline of seasonal ice, in large part due to anthropogenic global warming, has changed the timing of germination and growth. Prior to the last couple of decades, temperatures on the seafloor have been too cold to allow significant blooming events. That’s changed, said Anderson. “What we’re seeing now are very different Arctic Ocean conditions than anyone in living memory has known.” 

These modified conditions mean that species which are already vulnerable to climate change face an additional threat – one of those species just happens to be us. 

“The threat is clear, but we don’t yet know the extent to which these toxins will ultimately lead to increased human exposure or to impacts on the health of wildlife at all levels of the food web,” said NOAA researcher Kathi Lefebvre. 

Fisheries and coastal communities will be an integral part of managing this new risk factor. Lefebvre said that Alaskan coastal communities are now aware of this emerging issue and have helped throughout the research process to protect their subsistence life. These communities are also hoping to help advance our understanding of the changing Arctic and what it means for the future.

“We’ve learned from the Gulf of Maine in the Atlantic Ocean how to monitor and manage Alexandrium bloom events and how to sustain commercial and recreational fisheries in the face of HABs, but navigating this new Alaskan Arctic HAB problem is going to take a great deal of targeted research and far more attention to the food security of coastal residents and Alaska Natives and the health of Arctic wildlife than we’ve paid so far,” said Anderson. 

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By Alex Ruger, Earth.com Staff Writer