Learn about the research on algal blooms in Trout Lake

For the past year, researchers and residents of Sambaa K’e have been working to learn more about cyanobacteria, better known as blue-green algae, in Trout Lake.

Cyanobacteria is not actually algae, but a naturally occurring bacteria found in lakes, ponds, rivers and streams. It thrives in shallow, slow-moving water but is not limited to those type of water systems.

Cyanobacteria blooms occur when the bacteria mass produces a film on top of the water ranging from a scum to a thick-looking mat.

Jennifer Korosi, an associate professor at York University who studies inland waters, is leading the study of cyanobacteria in Trout Lake.

Korosi said she has been working in the NWT since 2018, originally researching permafrost effects on lakes at the Scotty Creek Research Station.

In 2022, Korosi proposed expanding that research to Trout Lake. Community leaders in Sambaa K’e expressed an interest in research being done on algal blooms.

The research project aims to monitor cyanobacteria that has been reported in Trout Lake since the early 2000s, but has never been previously tested.

Involvement of community members ‘essential’

Korosi, with the help of two students from York University, tested water from Trout Lake weekly to analyze baseline phytoplankton, temperature and oxygen in the lake. They also deployed equipment into the water to help with monitoring when they could not do it by hand.

Korosi said planning tests and field days for the project was challenging due to the “sporadic and short lived” nature of blooms in the area. To minimize missing blooms, she said two students stayed in Sambaa K’e from July to August 2024, with one student returning to the community in June 2025.

Throughout their time in Sambaa K’e, the team also trained youth from the community to assist in the maintenance and use of testing equipment.

“When we started working in Sambaa K’e we asked ‘what works best in terms of making sure the research benefits the community?’ And one of the things they mentioned is they really like it when they can get the youth involved in the research,” Korosi said.

“It worked out really well for us too, because of that issue of we’re not always going to be in the community when it happens. So having people in the community who can do it is really essential.”

Through monitoring, researchers were able to capture evidence of two blooms in Trout Lake.

Blooms becoming more common in NWT

Blooms can occur in calm, warm and nutrient rich water, which creates an environment for the algae to grow at a rapid rate.

Korosi said that blooms are not typically expected in northern lakes. She noted, however, that, in recent years, blooms have been found in cool waters and even underneath layers of ice.

Blooms have been spotted in the Yellowknife area and are becoming increasingly more common in the NWT.

While the cause of blooms cannot be directly attributed to one specific factor, Korosi said she expects wildfires have become a contributor.

“Wildfire ash can act as a fertilizer, it has nutrients in it. And there’s been some research in the states that have seen downwind transport of wildfire smoke plumes have stimulated blooms in lakes,” she said.

Korosi said that cyanobacteria, like all algae blooms, will deplete oxygen during growth and decomposition stages. This oxygen depletion can result in fish kills – the sudden death of a large number of fish.

Cyanobacteria can be identified by the look of oil or paint sitting on top of the water. It can range in colour from turquoise – hence the cyan in the name cyanobacteria – to green-brown, yellow, red, and even purple.

Certain species of the bacteria have the potential of creating toxins that can cause skin, liver and neurological issues.

Moving forward, Korosi said the research team plans to continue building a baseline understanding of cyanobacteria in the hopes that their data will help build awareness of the risks of the blooms.

“I’m hopeful that what we do can kind-of help with ongoing efforts in the GNWT to make decisions on how best to manage or monitor the problem, especially because you have a lot of remote communities that, by the time somebody comes from Yellowknife to sample it, it’ll be gone,” she said.

“So building that community capacity to recognize and respond to blooms to protect themselves.”

The research project was one of 30 environmental projects that received funding through the NWT’s Culminative Impact Monitoring Program last year. The program’s vision is “to watch and understand the land so that it can be used respectfully forever.”