Is algae the villain — or the victim — of a warming Muskoka?
By Kaitlyn Horton | Saturday, March 7th, 2026
Reports of algal blooms continue to become more frequent and for Muskoka residents, this can mean less time enjoying Muskoka’s beautiful lakes.
Occasionally, algal blooms can have deeper impacts when the right factors align for toxin production. One example exists in Alaska, where the bioaccumulation of an algal toxin in Alaskan shellfish has led to cases of paralytic shellfish poisoning among people who eat them.
While Indigenous tribes represent only 16 per cent of the population, they account for over half of PSP cases in Alaska. When government action wasn’t sufficient, the tribes launched their own monitoring program in 2016, with 17 taking part as of 2024.
While the marine environment of Alaska is a far cry from our freshwater lakes in Muskoka, similar concerns exist here. Toxic blooms in Muskoka remain very rare, but some residents still question the safety of swimming or eating fish from bloom-prone lakes.
Despite the fear, there is another side of algae that is rarely discussed. In one of my favourite television episodes, “What About Blob?” from the show “Bob’s Burgers” (Season 9, Episode 17), young Gene is amazed by the beautiful glow emitted by an algae bloom.
This bioluminescence is produced through the same mechanism used by fireflies. A yacht club owner wants to remove the unsightly bloom but reassures Gene he will use an “eco friendly” bleach powder!
Ultimately, his evil plan is ruined, but the bloom gets eaten by a group of fish anyway. Although Gene is upset at his loss, he understands this is part of the natural cycle of life. This story is a great reminder that when nature is left to its own devices, it’s pretty good at managing itself, and that algae have important ecological roles.
Algae are at the base of the food web, making them necessary to maintain ecosystem balance, despite how unpleasant some people may find them. They are always present in natural water systems, even when they aren’t blooming.
Through photosynthesis, algae absorb carbon dioxide and release oxygen to the atmosphere, and while we can also thank plants for this process, blue-green algae were doing it about two billion years earlier. Without blue-green algae, you would not be here today reading this.
Algae are also a food source for zooplankton, which are then food sources for fish. Wiping out algae entirely is not the solution, as they are necessary to support aquatic life.
The frequent blooms are the problem, not the algae, so we need to understand what’s triggering them. Although algae thrive when nutrients are abundant, Muskoka’s lakes have low nutrient levels.
Blooms are occurring more frequently in low nutrient lakes worldwide, indicating that a global factor such as climate change is contributing. Warm temperatures enhance algae growth, and can also cause greater oxygen depletion in deep lakes, enhancing nutrient resuspension from lake sediments.
There are surely many factors that contribute to algal blooms, and the answers will not be obtained overnight. This is why it’s important to study trends in algal blooms now, while blooms are occurring relatively infrequently.
Entering its eighth year, the Muskoka Watershed Council’s Algae Monitoring program was born out of this need to understand local trends.
The program collects data on the distribution, abundance and seasonality of algae in Muskoka with the help of citizen scientists in our lake association partners. The more data that can be collected, the easier it will be to identify conditions that are favourable for bloom formation, so if your lake association is not already participating, now is your time to get involved!
We specifically need data from lakes that are not prone to blooms so we can compare them to those that are. This also allows us to build a baseline for your lake before blooms start to occur. Together, we can learn more about the threats facing Muskoka so we can all be prepared for whatever the future brings.
This article was first published by MuskokaRegion.com.
Kaitlyn Horton
This is article No. 10 in the current series, Nurturing Our Watersheds, from Muskoka Watershed Council. Its author is Kaitlyn Horton, graduate of Guelph University (BSc) and Ontario Tech University (MSc), District of Muskoka employee providing technical support to MWC, and a brand new resident of Muskoka who looks forward to working with Lake Associations as we monitor algae. The series is edited by Peter Sale.