by Paige Jessup, Climate Change Resiliency Intern
Reports of blue-green algae in the Great Lakes have bloomed in the last decade. The increased public awareness has shed a light on the issue of eutrophication on freshwater lakes. However, there are other factors involved in the growth of algae like invasive species, overfishing, and food web alterations, all often caused by human activities (Pick, 2016). Canada is home to the largest concentration of freshwater lakes in the world, and one-fifth of the world’s fresh surface water comes from the Great Lakes. Freshwater lakes have become part of the Canadian identity and it is important that we protect this vital resource.
What Is Blue-Green Algae?
Blue-green algae, properly referred to as cyanobacteria, are commonly a unicellular photosynthetic organism that naturally occur in most lakes, ponds, rivers, and streams. These organisms typically are not visible to the naked eye. However, when these bacteria rapidly reproduce in preferable conditions that have sunlight, warm temperatures, and the presence of nutrients, a visible bloom can occur (Government of Ontario, 2022).
When a bloom of toxic blue-green algae takes over a lake, it sits on the surface of the water and blocks out sunlight for other aquatic plants and organisms. When these bacteria die-off, they use up much of the dissolved oxygen in the decomposition process and can release harmful cyanotoxins into the water. The result is a hypoxic waterbody that cannot sustain life which leads to wildlife die-offs. Cyanotoxins are extremely dangerous to humans, pets, and livestock. When a lake is experiencing a bloom of blue-green algae, the public and municipalities must take precautions to avoid coming into contact with the water and close beaches, and test and treat drinking water for cyanotoxins.
How Did Blue-Green Algae End Up In the Great Lakes?
Cyanobacteria has a long history in Canada. They occur in most lakes naturally in small quantities. Now, shores along each of the Great Lakes have experienced harmful cyanobacteria blooms, particularly around populated cities or towns where you see agricultural run-off, drainage of effluent from wastewater treatment plants, hardened shorelines, run-off from septic systems, and other forms of urban run-off.
To protect Canada’s freshwater resources, it is important that we reduce the amount of run-off pollution into the lakes. This can be achieved through improved stewardship practices in rural and agricultural watersheds, as well as innovative stormwater management approaches and naturalizing shorelines to reduce erosion. If you think you have spotted a possible blue-green algae bloom, be sure report it to your local Algae Watch Program and keep everyone safe.
This blog is part of a larger education toolkit about cyanobacteria. To access all of the resources from the toolkit, visit watersheds.ca/cyanobacteria
References
Government of Ontario. (2022). Blue-green algae. https://www.ontario.ca/page/blue-green-algae
National Ocean Service. (n.d.). What is eutrophication? Retrieved from https://oceanservice.noaa.gov/facts/eutrophication.html
Pick, F. R. (2016). Blooming algae: a Canadian perspective on the rise of toxic cyanobacteria. Canadian Journal of Fisheries and Aquatic Sciences. 73(7): 1149-1158. doi:10.1139/cjfas-2015-0470
The Great Lakes Commission. (n.d.). About the Lakes. Retrieved from https://www.glc.org/lakes/
The National Wildlife Federation. (n.d.). The Great Lakes. Retrieved from https://www.nwf.org/Educational-Resources/Wildlife-Guide/Wild-Places/Great-Lakes.
This piece is part of an education toolkit generously funded by:
