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 pets, fish, wildlife and livestock.

Blue-green algae (cyanobacteria) are a naturally occurring bacteria found in many New Brunswick ponds, lakes and rivers. They are not normally visible, but under certain conditions, can increase in numbers to form surface blooms or benthic mats.

“We want all residents to be active and enjoy the outdoors, but we also want them to understand and consider the potential risks of exposure to blue-green algae,” said Dr. Jennifer Russell, chief medical officer of health. “New Brunswickers are encouraged to familiarize themselves with blue-green algae’s appearance in order to minimize risks for themselves, loved ones and their pets.”

While most commonly blue-green in colour as its name suggests, surface blooms can also be green, red, brown or yellow. Benthic mats, which can form along the bottom of lakes and rivers, can look like clumps of vegetation that may 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 always things you can do to help protect yourself while enjoying recreational waters,” said Russell. “Algal blooms can be unpredictable, so it is important to always check the water before entering and to 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 after being in recreational waters.
  • Do not enter the water with open cuts or sores.
  • Always wash your hands before eating.

Pet owners are advised that benthic mats, including those that wash up along the shores of lakes and rivers, can be toxic and potentially lethal to dogs if consumed. Dogs are attracted to their odour and should not be permitted to eat vegetation or floating mats. As a precaution, children and adults should not play with or handle mats while wading, fishing, boating or otherwise enjoying recreational waters.

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.

The 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 is about blue-green algae is available online.