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MARATHON — Experts on aquatic ecosystems say confirmed reports of blue-green algae blooms on Lake Superior are a cause for concern, but the degree to which they’re tracked nowadays is much more robust than in the past.
The Thunder Bay District Health Unit and Parks Canada announced a confirmed cyanobacteria bloom at Hattie Cove in Pukaskwa National Park on Aug. 15. It was the first time a bloom had been confirmed at the site, according to public health records; it was also the first one confirmed by the health unit in its catchment area this year.
“It's both surprising and troubling,” said Scott Higgins, a senior research scientist at the IISD Experimental Lakes Area, a freshwater laboratory near Kenora backed by the International Institute for Sustainable Development.
“We've seen blooms in Lake Superior occasionally in the past decade or so, and, the troubling and surprising parts are, Superior is a very large lake and it's a very cold lake and it's not a lake where we would expect to find blooms in.”
Aside from the Hattie Cove bloom, a handful of others have been confirmed along the north Superior shore, dating back to 2019, which is as far as the health unit’s public records go. They include two in different spots in Shuniah in 2024, another in Shuniah in 2023, and one on Black Bay in 2021.
Experts say blooms have been confirmed further south in Lake Superior as far back as 2012. Their reports on the region’s inland lakes have been much more prevalent recently. The blooms can produce toxins, which can have a variety of ill effects on people and animals.
The fact that cyanobacteria blooms are being reported now on Superior doesn’t necessarily mean they’ve only just started happening, said Nathan Wilson, a PhD candidate at Lakehead University who specializes in research into blue-green algae. He said it could simply be a case of them getting more attention nowadays, and, with the health unit now tracking them, people may be more likely to file reports.
“At this point, that's what a lot of time and effort goes into is trying to figure out, is this something that is happening specifically because of climate change, or is there a new introduced key variant that's causing cyanobacteria to bloom on Lake Superior?” Wilson said.
“Or is it more just we didn't know to look for it in the past?”
He said it's also possible that the numbers are underreported as, aside from the blooms needing to be spotted in the first place in order to be reported, another issue is the work involved in many cases to access the site — especially along the Superior North Shore — so testing can be done.
“The blooms can be tricky, they can be there one hour and then an hour later they're not,” Wilson said.
Higgins agreed that there’s a lot more effort into reporting, tracking and publicly identifying blue-green algae blooms nowadays, and that technology has also helped greatly in that regard. But he also pointed to several broader factors that make Superior more hospitable to the algae today, leading to higher concentrations of it, which causes the blooms.
Those include a general warming of the lake, meaning it’s more sensitive to human activities in and around the watershed, and an increase in rainfall around the Great Lakes in general, including it coming in heavier events, over the past 20 or so years.
“This has been documented in Lake Superior that a number of the blooms that have occurred there are directly related to these high rainfall events, which means more water and more nutrients coming into the lake,” he said.
Overall, there has been more emphasis recently on keeping minerals like phosphorus and other nutrients that can enter bodies of water out of lakes and rivers — including changes to environmental regulations — in order to restrict the abundance of nutrients that help spawn the blooms, Wilson said.
Wilson said the increase in public interest around algae blooms — including notifying the province’s Spills Action Centre when one is suspected — is important.
“I think it's really good,” he said. “I think it's very much a win for the environment at this point.”
