Cyanobacteria are a phylum of aquatic bacteria that obtain their energy from the sun (through photosynthesis). They are often called “blue-green algae” but they are not algae. Aquatic cyanobacteria are known for their blooms that can have the appearance of bright green to brown paint or scum on the surface of the water. Fresh blooms smell like newly mown grass; older blooms smell like rotting garbage. These blooms can be toxic and lead to the closure of recreational waters when spotted. Cyanobacteria growth is favored in ponds and lakes where waters are calm but blooms can also occur as mats on the bottom of rivers and streams. Growth is also favored at higher temperatures. Cyanobacteria reproduce explosively under certain conditions and blooms usually occur in late summer and early fall. The blooms can be harmful to humans and animals if the cyanobacteria involved produce toxins. Cyanobacteria can produce neurotoxins, cytotoxins, endotoxins, and hepatotoxins, which are collectively known as cyanotoxins.
The NB Department of Health issues an advisory if a bloom is noted in a waterbody. Advisories help to inform local recreational water users, so that they can make informed decisions on water use in the affected area. Individuals should avoid swimming and any other recreational water-related activities in areas with blue-green algae blooms.
If you see a cyanobacteria bloom:
- Do not swim or engage in any other recreational activity that may involve contact with water
(e.g., water-skiing) in areas where a bloom is observed.
- Keep children, pets and livestock away. They may be more at risk of becoming ill.
- Do not drink the lake water. Boiling the water will not remove toxins.
Dr. Janice Lawrence is an associate professor of biology at UNB and has been studying blue-green algae in the Saint John river. She says there are large accumulations of blue-green algae along the bottom of the river bed, and those mats are ripping off the bottom rapidly now, and washing downriver. She says the volume of material is very concerning, and it’s toxic. CBC Interview with Dr. Janice Lawrence
2019 Cyanobacteria Monitoring
For more information, visit these links: