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

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NWAI on Twitter

@valentino_nora @seguincbc @watersCBC @infoamfred Thank you!

- 20 hours ago

Thanks @valentino_nora. It's great to have the support. Natalie Deseta is a eloquent presenter. https://t.co/6fsIjgFQTg

- 20 hours ago

Thanks @seguincbc @watersCBC @infoamfred for the opportunity to talk about smolt wheels on the Nashwaak River today.

- 23 hours ago

Rain gardens are designed to collect rainwater run-off, slow its movement, allowing it to filter back into the ground conducting it back into the water table. Read all about the @DailyGleaner article by John Chilibeck here: https://t.co/EnOMnHY8SX #eaunbwater #mynashwaak https://t.co/1BfSQnQXEL

- 5 days ago

Great webinar series on funding for #climateadaptations https://t.co/kc4tYaR57w

- 5 days ago

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NWAI on Facebook

Patricia Catherine Simmons

2 days ago

Patricia Catherine Simmons
Remember to sign up for Monday's Tree Talk about Restoring Fredericton's Silver Maple Forests by Dr. Natalie Deseta. Co-sponsored by the Nashwaak Watershed Associationtinyurl.com/TMF-12Apr21 ... See MoreSee Less

Let's Talk Trees! Free Online Mon Night Speaker Series to April 26th

tinyurl.com

Trees Matter Fredericton Free Online Speakers Series on everything urban nature - Mondays 7-8pm, to Apr 26th
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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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