FREDERICTON (GNB) – The public is reminded that some types of blue-green algae produce toxins which can cause skin, eye and throat irritation. More serious health effects such as gastrointestinal illness can occur if toxins are consumed. These toxins can also be harmful to fish, wildlife, livestock and domestic animals.

“We understand residents want to be active and enjoy the outdoors, but they should consider the potential risks of exposure to blue-green algae,” said Dr. Cristin Muecke, deputy chief medical officer of health. “New Brunswickers should familiarize themselves with blue-green algae’s appearance, in order to avoid any of the risks associated with it this summer for themselves, their loved ones and their pets.”

Blue-green algae (cyanobacteria) is a naturally occurring bacteria found in New Brunswick’s aquatic ecosystem but, under certain conditions, can increase in numbers to form surface blooms or benthic mats. These tend to occur during the warmer months.

The public health advisory that was issued in 2019 for the Saint John River between Woodstock and Fredericton due to the presence of benthic mats remains in effect.

Pet owners are advised that benthic mats that wash up along the shores of lakes and rivers can be toxic and particularly harmful to dogs. Dogs are attracted to their odour and should not be permitted to eat vegetation or floating mats, as they can be lethal if consumed.

While most commonly blue-green in colour, surface blooms can also look green, red, brown, or yellow. Benthic mats form along the bottom of lakes and rivers and can look like clumps of vegetation that can appear black, brown or dark green in the water, but when washed up on the shore they may appear brown or grey once they have dried. They can also be attached to rocks or aquatic vegetation.

“There are things you can do to help protect yourself while enjoying our recreational waters,” said Muecke. “Algal blooms can be unpredictable, so it is important that people always check the water before entering and avoid swimming in areas where there are visible blooms or mats.”

Other safety advice includes:

  • Always supervise young children and pets near recreational waters.
  • Do not swallow lake or river water.
  • Bathe or shower immediately after swimming.
  • Do not enter the water with open cuts or sores.
  • Always wash your hands before eating.
  • Do not handle benthic mats when wading, fishing or boating.

The provincial government supports various blue-green algae research projects through the Environmental Trust Fund. These projects, which are underway in the Saint John River and several lakes in the province, are intended to build a better understanding of the distribution of blue-green algae and their toxins.

More information about blue-green algae is available online.