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Blue-Green Algae (Cyanobacteria)
Cyanobacteria, or blue-green algae are a concern. Under certain conditions, some strains can produce toxins that are harmful to human or animal health. Commonly found in shallow, warm, and slow moving or still water (including freshwater ponds), cyanobacteria can quickly multiply. This can lead to algal 'blooms'. Cyanobacteria blooms are frequently a bright turquoise green (hence the name blue-green algae), but colours can vary from olive or yellow-green to dark green and even purple.
The cause of algal blooms is not certain, but it is thought to be related to nutrient levels in the water.
Blooms are most common when phosphorus levels are elevated and nitrogen levels are relatively low. Like some higher plants, cyanobacteria are able to 'fix' from the air the nitrogen they need for growth.
Although cyanobacteria blooms are common in other parts of Canada, only three have been documented in PEI in the past decade:
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)
Blue-green algae blooms
Potential Animal and Human Health Impacts
Blue-green algae blooms often form a scum on the surface of freshwater ponds and lakes. The algae can cause skin rashes and irritation of the eyes for swimmers who come into contact with the scum. Humans that accidentally drink the water while swimming 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 have the potential to produce toxins, it is wise to treat them with caution. When a heavy growth of blue-green algae is confirmed, PEI's Chief Health Officer will issue a public advisory. Signs are then 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 a particular bloom is toxic is through laboratory analysis.
Monitoring for Blue-Green Algae
The PEI Department of Environment, Labour and Justice responds to reports of heavy algae blooms by taking samples for examination. If a bloom is identified, public advisories will be posted on this website.
If you see what you suspect is a blue-green algae bloom, please contact the Department of Environment, Labour and Justice at (902) 368-5044 as soon as possible.
