What Exactly Is Blue Green Algae?

by | Aug 14, 2020 | News | 0 comments

Blue Green AlgaeBlue-Green Algae-During these sunny summer months and into early fall, blue-green algae starts to wreak havoc in our water bodies. But what exactly is blue-green algae? How is it potentially harmful? And what causes it?

What is it and what does it do?

Blue-green algae is a naturally occurring plant-like organism, found in shallow, warm, and/or slow-moving waters. Although often they are blue-green in colour, they can also be olive-green or red.

Although it’s commonly referred to as blue-green algae, it’s actually bacteria (scientific name: Cyanobacteria), that can produce toxins harmful to people and animals. The harmful toxin in blue-green algae is called microystin. Microystin is mainly released from the blue-green algae when the cells of the bacteria break open or die. This can happen due to cooler weather, rainfall, and windy conditions.

While not all kinds of blue-green algae are toxic, if you suspect you’ve come across blue-green algae, don’t drink the water, bathe or swim in it. Make sure to keep your pets out of it, too. Health Canada has stated that human reactions range in severity. While some toxins can attack the liver or the nervous system, others may just irritate the skin and eyes. Contact with blue-green algae blooms can be lethal to pets.

Algal blooms, not only impact human and pet health, but also ecological health. Thick algal blooms can prevent the growth of aquatic plants, and in turn, impact aquatic species that rely on the vegetation for food and nurseries. As algae decay, it consumes oxygen and releases carbon dioxide which can create “dead zones” in the water, areas of hypoxic conditions (low or no oxygen) in which very few organisms can survive. Lastly, heavy rains and warmer temperatures due to climate change are altering ecosystems and increasing runoff, which can further promote the growth of algal blooms.


In freshwater environments, phosphorous and nitrogen are limiting nutrients, in that they either limit or excel an organism’s growth. An excess of these nutrients in freshwater, known as nutrient loading, leads to uncontrolled growth of cyanobacteria, or algal blooms.

Nutrient loading is caused by fertilizers (synthetic and organic) used in agricultural practices, urbanization and human waste, and household products containing phosphorous compounds such as detergents. The excess dissolved phosphorous and nitrogen can enter nearby water systems by runoff or leaching. This increases the growth of cyanobacteria as it feeds on dissolved nitrate and phosphate, producing these murky, green algal blooms.

How Can We Help Prevent the Growth of Algal Blooms?

There are several simple things that can be done to help reduce external nutrients going into our water bodies:

• Use phosphate-free products;
• Avoid/reduce fertilizing your lawn;
• Maintain a natural shoreline on lakes and riverfront properties;
• Check septic systems regularly for leaks;
• And pick up pet waste

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