The Nashwaak Watershed

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Cyanobacteria

Cyanobacteria bloom in Lake Erie

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, they are bacteria. They are a natural and essential part of our rivers and lakes and have existed for billions of years. Cyanobacteria are not normally visible, but with the right conditions (warm temperatures, sunlight, flow, and food – nutrients) populations can grow quickly and clump together to form what is called a bloom.


While not all cyanobacteria are harmful, some can produce toxins (cyanotoxins) that are harmful to humans. If you swim in water containing toxins, you may experience skin, eye, and/ or throat irritation. More serious effects, such as gastrointestinal illness, can occur if toxins are consumed.

Surface Blooming Cyanobacteria

Surface blooming cyanobacteria are what people commonly think of when they hear cyanobacteria bloom. They can look different depending on the size of the bloom and species of cyanobacteria. They are most likely to form in warm, slow moving water like lakes and bays.

These blooms can produce cyanotoxins. Most commonly, they produce microcystin which is known to cause skin irritation, gastrointestinal illness, and can cause more severe illness if ingested.

How to Spot a Bloom?

  • Blooms most commonly look like green or blue-green scum along the surface of the water but other colours are possible. If the bloom is thick it may appear as though paint or hydroseed has been spilled on the water. Wind/waves can cause blooms to accumulate along the shore.
  • When a bloom is forming, or wind/wave action has dispersed the bloom, the water can appear cloudy. The water may also appear clear with small green or blue-green globules (balls) or flecks suspended in it.
  • Fresh blooms can smell like newly mown grass and older blooms can have a foul smell.
  • Blooms can appear and disappear quickly

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.

To learn more about the health impacts and what you can do to protect yourself visit gnb.ca/algae.

Benthic Cyanobacteria

Benthic cyanobacteria may form mats along the bottom of flowing streams and rivers. Benthic mats contain a mixture of cyanobacteria and algae. Unlike a surface bloom, these mats can be present in water that is clear. Some species of benthic cyanobacteria can produce neurotoxins called anatoxins. Human poisonings are unlikely as most people are unlikely to ingest mat material. These toxins can cause skin irritation, gastrointestinal issues, and/or numbness or tingling of fingertips and around the mouth if ingested.

Dogs and wildlife are attracted to the scent of decaying mat material and are at a greater risk of poisoning as they are more likely to ingest fatal doses.

How to Spot a Benthic Mat?

  • Mats are clumps of vegetation that can appear as scum on rocks, mud, or other vegetation along the bottom of the stream or river. They can be dark brown, black, or dark green.
  • Mats can also have a spongy appearance as they float to the surface.
  • On the shoreline, mats become dry and can appear light brown or grey. Dried out, washed up mat material may still contain cyanotoxins.
Cyanobacteria can also grow as mats on the river’s substrate

What to do 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.

For more information, visit these links:

Cyanobacteria InfographicDownload

ACAP Saint John

NB Department of Health FAQs,

Health Canada,

Conservation Council Article from 2018

CBC Interview with Dr. Janice Lawrence

Part 1 Cyanobacteria Panel of Experts

Part 2 Cyanobacteria Panel of Experts

Part 3 Cyanobacteria Panel of Experts

Stay in-touch!

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Upcoming Events

  1. Paddle down the Nashwaak River

    August 22 @ 5:30 pm - 7:30 pm
  2. Explore the Nashwaak River

    September 12 @ 5:30 pm - 7:30 pm

View All Events

Upcoming Events

  1. Paddle down the Nashwaak River

    August 22 @ 5:30 pm - 7:30 pm
  2. Explore the Nashwaak River

    September 12 @ 5:30 pm - 7:30 pm

View All Events

NWAI on Twitter

@WatershedsCAN Congratulations on the appointment of Robert Pye!

- 3 days ago

@CanadaTrees: Tree planting can help restore ecosystem and climate health—but only if it's done with those long-term goals in mind. As ED Daimen Hardie points out in @globeandmail, forest resilience depends on a greater diversity of tree species being planted. https://t.co/eIcPwcwWC9

- 3 days ago

We have an amazing new sign for our restoration site at Neill's flats! Many thanks to Doug Daley and the team at Kiers Marketing for their design work, Allan Tremblay for the translation and our summer student Ryan Totten for designing and building the gorgeous frame. https://t.co/xiFkhwlcVJ

- 8 days ago

Executive Director Marieka Chaplin was honoured to receive a Gulf of Maine Council 2022 Visionary Award, on behalf of the NWAI. The award recognizes outstanding innovation, creativity, and commitment to protecting natural resources within the Gulf of Maine. https://t.co/bX5rNGaleF

- 14 days ago

The (Nashwaak) watershed is home to 38 species of mammals, 15 species of amphibians, 7 species of reptiles, more than 200 species of birds, and more than two dozen species of fish. " -Philip Lee, author of the Restigouche – The Long Run of the Wild River. #natureconservationday https://t.co/YH62RTBAJf

- 14 days ago

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Nashwaak Watershed Association Inc.

Nashwaak Watershed Association Inc.

Nashwaak Watershed Association Inc.

22 hours ago

Nashwaak Watershed Association Inc.
Thanks so much to the volunteers who helped us count monarch caterpillars and eggs this week! We examined 265 stems of common milkweed along the trails and found 32 caterpillars and 11 eggs. Thanks Nature NB for helping us participate in the monarch bioblitz! ... See MoreSee Less

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Nashwaak Watershed Association Inc.

3 days ago

Nashwaak Watershed Association Inc.
This Friday, along with the The Nature Trust of New Brunswick, we are welcoming volunteers to assist in the restoration efforts along the Marysville Flats.To register, click the link below:www.eventbrite.ca/e/376768483677 ... See MoreSee Less
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Nashwaak Watershed Association Inc.

4 days ago

Nashwaak Watershed Association Inc.
Looking for an excuse to get outside after all this rain? Join us tomorrow (Tuesday) evening to look for monarch eggs and caterpillars! No need to register - just meet us in the parking lot of York Arena (891 Barker St.) at 6:30 for some citizen science and fresh air!! ... See MoreSee Less

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Contact Us

Mail:
Nashwaak Watershed Association Inc.
P.O. Box 314, Station “A”
Fredericton, NB
E3B 4Y2

Office:
181 Westmorland Street
Fredericton, NB
E3B 3L6
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Phone: 506 261-4664
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