The Growing Threat of Toxic Algal Blooms in Lake Winnipeg

Lake Winnipeg, one of Canada's largest freshwater lakes spanning over 24,000 square kilometers in Manitoba, has long battled recurring harmful algal blooms dominated by cyanobacteria. These microscopic organisms, often misidentified as blue-green algae despite being bacteria capable of photosynthesis, thrive in nutrient-rich waters fueled by agricultural runoff high in phosphorus and nitrogen. By 2006, these blooms were labeled the worst in any large temperate freshwater lake globally, visible even from space with vivid green streaks covering hundreds of kilometers.

The blooms not only discolor the water but produce cyanotoxins like microcystin and beta-N-methylamino-L-alanine (BMAA), a neurotoxin linked to neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and Alzheimer's. In 2013, Lake Winnipeg was dubbed the world's most threatened lake due to these eutrophication pressures. Health advisories close beaches, disrupt recreation, and threaten the lake's walleye fishery, a cornerstone of Manitoba's $100 million-plus commercial and sport fishing economy.

Climate change exacerbates this by warming surface waters—Canadian lakes heat twice as fast as global averages—prolonging ice-free periods and intensifying nutrient cycling. Shifts from diatoms to cyanobacteria dominance alter the food web, impacting zooplankton, fish, and ultimately human users including Indigenous communities who rely on the lake for traditional practices.

Pioneering Virus Research at the University of Winnipeg

Enter Dr. Emily Chase, assistant professor of biology at the University of Winnipeg (UWinnipeg), whose lab launched the first-ever study of microalgae viruses in Lake Winnipeg starting summer 2025. This breakthrough illuminates an overlooked virus-algae dynamic: viruses that specifically infect cyanobacteria and eukaryotic microalgae, acting as natural regulators of bloom cycles.

"Viruses, in particular ones that are infecting microalgae, are overlooked. We're kind of missing a key step in the process of understanding Lake Winnipeg," Chase notes. Her work, funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Lake Winnipeg Research Consortium (LWRC), employs multi-omics—combining metagenomics, transcriptomics, and proteomics—to map viral diversity, evolution, and host interactions.

The Chase Lab's focus on Lake Winnipeg addresses a eutrophic system prone to harmful algal blooms (HABs), where viruses induce lysis: the host cell bursts, releasing progeny viruses and nutrients that can trigger secondary blooms but also terminate prolonged outbreaks.

Unraveling the Virus-Algae Infection Cycle Step by Step

The infection process begins when a virus attaches to a microalgal cell's receptor, injecting genetic material. Inside, it hijacks the host's machinery for replication, often impairing photosynthesis and primary production. Lysis follows, collapsing dense blooms and recycling nutrients.

• Attachment and Entry: Virus binds to specific surface proteins on cyanobacteria like Dolichospermum or Microcystis.
• Replication: Viral DNA/RNA commandeers ribosomes, halting host functions.
• Assembly and Lysis: New virions assemble; enzymes degrade the cell wall, releasing 100-200 viruses per cell.
• Dispersion: Progeny infect nearby hosts, amplifying control in high-density blooms.

This dynamic, previously excluded from predictive models, explains sudden bloom crashes observed in satellite imagery. Chase's early data promises to refine forecasts, vital as climate projections indicate more frequent HABs.

Dr. Emily Chase: From Global Expertise to Manitoba's Lakes

Joining UWinnipeg in 2025, Dr. Chase brings a PhD from Aix-Marseille Université (Mediterranean microalgae viruses) and postdoctoral work at Vanderbilt University. Her lab trains MSc/PhD students in sequencing, bioinformatics, and field sampling, with openings for Autumn 2026. "It’s a new frontier, so everything that we find will be meaningful," she says, emphasizing trainee-led discoveries.

For aspiring researchers, opportunities abound in aquatic virology. Explore research jobs or research assistant positions in Canadian universities tackling environmental challenges.

Research Methods: From Lake Sampling to Genomic Insights

Over the past year, Chase's team collected water samples across Lake Winnipeg's north and south basins during peak bloom seasons. Lab techniques include:

• Metagenomic sequencing to identify novel viruses.
• Culturing host-virus pairs for infection assays.
• Environmental metadata integration (temperature, nutrients).

Initial findings, slated for public release by late 2026, will inform LWRC models. Learn more on UWinnipeg's site.

Climate Change: Why Viral Dynamics Matter Now

Warming trends—Lake Winnipeg's ice cover shrinking—favor cyanobacteria over beneficial diatoms. Longer summers boost stratification, trapping nutrients. Viruses may buffer this, but shifting temperatures could alter host resistance. "We need to understand viruses to understand climate change," Chase asserts, aiding models for fish stocks and tourism.

Projections mirror Lake Erie's ice-free trajectory, risking intensified bloom-bust cycles releasing toxins en masse.

Economic and Ecological Ripples Across Manitoba

Blooms shutter beaches, costing tourism millions annually; walleye fisheries, valued at tens of millions, suffer from disrupted food webs. Zebra mussels exacerbate by filtering beneficial algae, promoting toxin-producers. Chase's work promises sustainable management, benefiting Canadian higher ed communities studying limnology.

Human Health Risks and Cyanotoxin Realities

Microcystin causes liver damage; BMAA, detected in Lake Winnipeg, bioaccumulates in fish. Swimmers risk skin rashes, pets fatal poisoning. Proactive monitoring via Manitoba government advisories is crucial, enhanced by viral bloom predictors.

Collaborative Efforts in Canadian Higher Education

UWinnipeg leads, but peers contribute: University of Manitoba's Centre for Earth Observation Science tracks blooms via satellites; University of Waterloo explores cyanophage biocontrol. These efforts position Canadian universities as global leaders. Check research career advice adaptable to Canada, or professor jobs in environmental science.

Photo by Cohen Berg 🇨🇦 on Unsplash

Toward Solutions: Modeling, Mitigation, and Careers

Integrating viral data refines hydrodynamic-biogeochemical models for nutrient caps. Best practices include precision agriculture reducing runoff, wetland restoration. For students, Chase Lab offers hands-on training; broader opportunities at postdoc positions or university jobs.

In conclusion, UWinnipeg's breakthrough heralds precise HAB management amid climate pressures. Rate professors like Dr. Chase at Rate My Professor, explore higher ed jobs, or seek career advice to join this vital field.