New Brunswick is seeing more reports of cyanobacteria blooms in provincial waterways, researchers say.
Meghann Bruce, a biologist at University of New Brunswick’s Canadian River Institute, said there has been a rise in reports of cyanobacteria, commonly referred to as blue-green algae.
“It could be a green paint-like scum on top of the water, but it could also be like a thick mat or a carpet that actually grows on the bottom of the water,” Bruce said. “It may look like specks or grass clippings, or even wet wool almost.”
So far this year, there have been 15 reports of cyanobacteria, a photosynthetic bacteria that is not necessarily harmful, although certain types can be toxic to humans and animals.
According to Bruce, this is a significant increase from the previous three reports in 2024.
Lower water levels a factor
Bruce also said the summer’s more extreme hot and dry weather, compared to last year, has lowered water levels, which adds to the likelihood of blooms.
“Warm still water creates ideal conditions for some types of cyanobacteria, some types of algae to grow quickly,” she said. “So low flows and low water levels mean less mixing and dilution, so blooms can build up and persist.”
Bruce said water levels in New Brunswick rivers are comparable to what they were in 2020, which was considered big bloom year.
However, increased public awareness about the bacteria might be the main contributing factor to the rise in reports, she said.
“There’s a lot more discussion in the public. This year there’s five new reported blooms, and those five new sites are likely the result of increased monitoring, [and] increased awareness of knowing what to look for.”
The rest of the blooms were reported in areas where cyanobacteria was known to bloom, she said. Of the five new blooms, three were benthic blooms at the bottom of rivers, and two were surface blooms.
Benthic blooms, which can look like a slimy film, are considered toxic because of how densely concentrated they are.
Bruce said there has been a recent increase in benthic cyanobacteria at monitoring sites in the Wolastoq, or St. John River, but she said it’s too early to determine if 2025 will be a significant bloom year.
The Canadian River Institute samples several sites all along the river.
Fredericton area has history
Bruce said researchers focus on the Fredericton region, from the Matacquac Dam down to Lincoln, because of consistent reports of blooms and the water’s proximity to the public.
So far, she said, the number of blooms observed have been similar to previous years, but the bloom season is not over.
“We can just say that they are there, they are growing, and will continue to grow if conditions persist,” she said.
“Only time will tell if it’s a significant bloom year.”
Catherine Evans, a senior analyst for DeepSense, a data scientist organization that supports academic research in the ocean economy, agreed it’s uncertain whether blooms will continue to increase.
Catherine Evans, a senior data analyst a DeepSense, says that over the years cyanobacteria blooms have increased globally and are projected to increase in frequency and severity the next 50 to 100 years. (Submitted by Catherine Evans)
But globally, there has been a significant increase in cyanobacteria blooms, she said.
Evans’s work focuses on satellite data, which shows an increase in cyanobacteria over the past couple of decades. She said it is projected to increase both in frequency and severity because of the hotter and drier weather conditions.
“There’s is all this sun beating down [and] there’s no rain filling up our watershed, and that allows a lot of rain and a lot of water in our lakes and rivers to evaporate,” she said. “It also increases the concentration of nutrients from runoff, either from sewers or agriculture.”
“With a higher concentration of those nutrients in our water and a higher temperature, that makes an algae bloom more likely to happen.”
Precautions for people and pets near water
Both Evans and Bruce said that with more new bloom sites discovered, people should be more careful around bodies of water.
They suggest people check for health advisories and take precautions when swimming at beaches, rivers, and lakes.
Additionally, Bruce and Evans said that cyanobacteria does not always look blue-green — it can be yellow, or even orange, so they recommend people look for anything in the water that is unusual.
Benthic cyanobacteria can be very toxic because it is a dense concentration of the algae, Evans says. (Submitted by Meghann Bruce)
If you have been exposed to cyanobacteria by accident, either by touching it or ingesting it, Evans suggested rinsing with soap and water. If you start feeling sick, she advises going to the hospital.
She also suggested taking a picture of the algae and reporting it the Department of Environment by calling its regional offices and by providing information such as:
Name and location of the affected body of water. The kind of body of water (lake, stream, or pond, for instance). Colour of the bloom or mat. Whether there is a yellow scum on the surface, since this could be pollen. How long the issue has been occurring.