Cyanobacteria, or blue-green algae blooms, are not common in PEI but can be a concern as some strains can produce toxins that are harmful to human or animal health. In PEI cyanobacteria can be found in shallow, warm, and slow moving or still water (including freshwater ponds). Under certain conditions cyanobacteria can quickly multiply or 'bloom'. Cyanobacteria blooms can appear as a bright turquoise green (hence the name blue-green algae), but colours can also vary from olive or yellow-green to dark green and even purple. When a bloom is very heavy, mats or scums can form on the surface of the water.
The cause of cyanobacteria blooms is not certain, but it is thought to be related to levels of phosphorus in the water. Although cyanobacteria blooms are common in other parts of Canada, since 2004 only the blooms listed below have been documented in PEI:
| Date | Location | |
|---|---|---|
| October 2004 | MacLure’s Dam, Murray River | |
| July - August 2005 | MacLure’s Dam, Murray River | |
| July - August 2005 | Clark’s Pond, Cavendish (PEI National Park) | |
| July - August 2008 | Clark’s Pond, Cavendish (PEI National Park) | |
| August - October 2010 | MacLure’s Dam, Murray River | |
| August - October 2013 | MacLure’s Dam, Murray River | |
| July 2015 | Campbell’s Pond, Cousin’s Shore | |
| August – October 2015 | Doyle’s Pond, St. Felix | |
| August - September 2016 | Clark's Pond , Cavendish (PEI National Park) | |
| August 2018 | MacLure's Dam, Murray River | |
| September - October 2018 | Treatment Lagoon, O'Leary | |
| August - September 2020 | MacLure's Dam, Murray River | |
| August 2022 | Black Pond, Souris | |
| August 2022 | MacLure’s Dam, Murray River | |
| July 2023 | Black Pond, Souris | |
| July 2023 | Campbell’s Pond – Dalvay | |
| August 2023 | MacLures Dam – Murray River | |
| August 2023 | Long Pond - Dalvay | |
| June 2024 | Black Pond, Souris | |
| June 2024 | MacLure’s Dam, Murray River | |
| June 2024 | Parson's Creek, Stanhope | |
| June 2024 | Point Deroche Pond, Blooming Point | |
| July 2024 | Ponds Road Pond, Pinette | |
| June 2025 | Parson's Creek, Stanhope | |
| June 2025 | Black Pond, Souris | |
| June 2025 | MacLure’s Dam, Murray River |
What are the health concerns?
Cyanobacteria blooms can sometimes produce toxins which can cause skin rashes and irritation to the eyes of swimmers, boaters, or others who come into contact with the toxins. Humans who accidentally drink water containing large amounts of cyanobacteria can experience nausea, vomiting, sore throat, diarrhea, or cramps. Livestock, pets, terrestrial wildlife, and aquatic life can also be harmed.
Because blue-green algae blooms may have the potential to produce toxins, it is wise to treat them with caution. If a heavy growth of blue-green algae is confirmed, PEI's Chief Health Officer will issue a public advisory. Signs will be posted advising the public to avoid swimming in, or eating fish from the water and to keep animals from drinking the water.
The only way to confirm whether or not a particular bloom is toxic is through laboratory analysis.
What do I do if I see blue-green algae?
If you see what you suspect is a blue-green algae bloom, please contact the Department at (902) 368-5044 or, if after hours, at 1-800-565-1633 as soon as possible.