Blue-green Algae (Cyanobacteria)
Note:
On August 4, 2023 Alberta Health Services (AHS) issued a blue-green algae (cyanobacteria) bloom advisory for Wabamun Lake.
Shoreline at Fallis, August 14, 2019
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What does the advisory mean?
While the advisory is in effect, “Residents living near the shores of this lake, as well as visitors to this lake, are advised to take the following precautions:
Avoid all contact with blue-green algae (cyanobacteria) blooms. If contact occurs, wash with tap water as soon as possible.
Do not swim or wade (or allow your pets to swim or wade) in any areas where blue-green algae (cyanobacteria) is visible.
Do not feed whole fish or fish trimmings from this lake to your pets.
Consider limiting human consumption of whole fish and fish trimmings from this lake, as it is known that fish may store toxins in their liver. (People can safely consume fish fillets from this lake).” (AHS advisory for Wabamun Lake)
The blooms were only seen in localized areas along the western shore. Cyanobacteria is of greatest concern when it can be seen in the water. From the advisory: “Please note that areas of Wabamun Lake in which the blue-green algae bloom is NOT visible can still be used for recreational purposes, even while this blue-green algae Health Advisory is in place.”
Go to AHS News & Advisories for the latest health updates on advisories for Wabamun Lake and other areas of the province, including what advisories are still in effect and those that have been lifted.
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What is the Concern?
Once a lake’s water chemistry supports cyanobacterial blooms, it is hard to prevent them in the future. Such blooms curtail enjoyment of the lake and threaten the health of aquatic ecosystems including fisheries, not to mention losses in property values. Cyanobacteria is a common component of a prairie lake ecosystem. Blooms occur when conditions—such as increased nutrient concentrations, sunlight, temperature, wave action—allow the cyanobacteria to multiply rapidly.
What Can You Do?
Stop use of fertilizers and pesticides in the watershed. Instead, mulch your cut grass and fallen leaves, and use compost in your garden.
Have your sewage system inspected to ensure no sewage or grey water is entering the water table. Replace outhouses and septic fields with holding tanks.
Plant native vegetation along the shoreline and upland areas to slow and clean runoff.
Protect wetlands in the watershed. Wetlands are natural filtres that stop nutrients before they enter the lake.
If you are planning to modify your shoreline, you must obtain authorization from Alberta Environment and Parks and possibly your municipality to ensure the modification does not harm the lake. For more information, go to Shoreline Modification Information.
Support the activities of the volunteer-run WWMC in its mission to protect the health of Wabamun Lake. Go to Get Involved to become a member (it’s free), volunteer and donate to our programs to research the biology of the lake and inform lake residents and users how they can help.
Some Facts about Cyanobacteria
Cyanobacteria species occur naturally in prairie lakes, their populations limited by water temperature and amounts of phosphorus, nitrogen and other nutrients in the water.
When conditions are right, cyanobacteria species will reproduce rapidly causing algal blooms. Many species form mucilage mats that foul beaches, boats, motors, docks etc. When blooms die and decompose they release ammonia and consume dissolved oxygen in the water, potentially killing aquatic life, including fish.
However, the most serious danger posed by cyanobacteria are the toxins several species create and release in the water. Depending on the species, the toxins can be broken down into three groups: dermatotoxins that attack the skin, neurotoxins that attack the nervous system and hepatotoxins that attack the liver.
Dermatotoxins can cause mild to severe reactions in humans, including irritations to eye, ear and throat; and skin rashes and lesions. For example, late summer “swimmer’s itch” is most likely caused by a cyanobacterial dermatoxin.
Neurotoxins can cause paralysis, seizure and death, depending on the amount of toxin consumed. Many deaths of dogs, other pets, livestock and wildlife along lakeshores in late summer can be attributed to cyanobacterial neurotoxins.
Hepatotoxins can also be quite deadly because they attack an animal’s liver, whether the animal be fish, fowl, pet or person. One such toxin, microcystin, is very persistent, able to survive boiling and freezing.
For more information about cyanobacteria, go to Alberta Health Services’ Frequently Asked Questions (PDF), as well as the Alberta Lake Management Society’s cyanobacteria page.
For more information on nutrients in lake water, go to our Reducing Nutrient Loading page.