What are cyanobacteria (blue-green algae)?

Last updated on June 13, 2022

Cyanobacteria (also known as blue-green algae) are naturally occurring microscopic bacteria that are common to freshwater ecosystems across B.C.

They are commonly called blue-green algae as they share some key features with algae, such as being aquatic organisms that are capable of photosynthesis. However, it wasn't until the advent of high-powered microscopes that cyanobacteria were correctly identified as bacteria.

In most circumstances, cyanobacteria cause no apparent harm in waterbodies, but when conditions favour their growth (e.g., warmer water temperatures, high nutrient concentrations, stable conditions), they can multiply very quickly and create a bloom. These "cyanoblooms" can occur in a variety of colours including blue-green, green, brown, blue, white, and red. Also, depending on the species and abundance, their appearance in waterbodies can be quite varied (e.g., pea soup or paint-like, small grass clippings, globular or bead-like, fluffy or pom-pom-like).

aphanizomenon cells (1)

A common cyanobacteria (Aphanizomenon flos-aquae) colony under 400X magnification.

Aphanizomenon surface

A surface bloom of the cyanobacteria Aphanizomenon flos-aquae in Ellison Lake, B.C.

Warning iconCyanobacteria blooms are of particular concern as there are several species capable of producing toxins that can be harmful to humans, domestic animals, and livestock. They can produce potent liver toxins, neurotoxins, as well as skin irritants. However, not all cyanobacteria are toxic, and even toxic species do not always produce toxins.

If you are concerned and want to report a cyanobacteria bloom in a body of water used for drinking water or for recreation, contact your local health authority.

For more information about cyanobacteria health concerns, visit HealthLinkBC.

When in doubt, stay out!

Harmful algal blooms

The following video from the North American Lake Management Society (NALMS) talks about the human and environmental health effects of Harmful Algal Blooms (HABs).

This video from the North American Lake Management Society (NALMS) talks about the human and environmental health effects of Harmful Algal Blooms (HABs).

Pavilion Lake YouTube video from Cold Water DiverDid you know Cyanobacteria made history? Other facts about Cyanobacteria!

Pavilion Lake in B.C. is part of extensive research projects by both NASA and the Canadian Space Agency (CSA) due to the freshwater microbialites that live in the lake.  Microbialites resemble corals and form over thousands of years, providing important information on the history of aquatic environments.

Microbialites are made from carbonate precipitates.  One of the best known carbonate-producing bacteria are cyanobacteria!

Watch a video about Pavilion Lake from Cold Water Diver (external link).


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What are Algae?

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What causes an algae bloom?


Image references

(1) Source: https://www-cyanosite.bio.purdue.edu/

All other photos are from Ministry of Environment and Climate Change Strategy staff files

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Oil spill by James Fenton from the Noun Project

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