Nova Scotia launches blue-green algae public service announcements and blooms reporting site

A medium-density bloom of blue-green algae species is seen in Nova Scotia, near the shoreline of a lake. Photo credit: Department of Environment and Climate Change

Nova Scotia has launched a new public awareness campaign to highlight the health risks surrounding blue-green algae in lakes, ponds, rivers and streams.

Under the campaign, provincial officials released a new website where people can share and report their algae findings. But, if residents aren’t sure what to look for, there are also new photo and video explainers, as well as beach signs to help educate Nova Scotians about cyanobacteria-forming toxin-producing blooms.

“Nova Scotians are noticing the impacts of climate change, and seeing more blue-green algae is a perfect example,” announced Municipal Affairs and Housing Minister John Lohr in a statement. “We want everyone to enjoy water activities and all Nova Scotia has to offer, but safely. Knowing what to look for allows people to be alert and make informed decisions,” added Lohr.

As the campaign launched, Nova Scotia was already warning residents about the first blue-green algae sighting of the year. It occurred last week in a stream between Shubenacadie-Grand Lake and Fish Lake, near a popular swimming area.

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Warm weather occurring so early in spring has made the risk of blue-green algae even greater, provincial health officials said.

“As the weather gets warmer — during this summer season and longer term due to climate change — we can expect to see more of these algae blooms. Taking the time to learn what to look for and sharing this information with friends and family will help us to live with blue-green algae as safely as possible,” stated Dr. Robert Strang, Nova Scotia’s chief medical officer of health, in a provincial announcement.

Despite the name, officials said blue-green algae can actually be turquoise, green, brown, red, white, or mixes of these colours. The blooms can resemble fine grass clippings in the water, spilled paint or pea soup. Sometimes they look like a thick scum on the surface, and often smell musty or grassy when healthy, and like ammonia when decomposing.

Animals may be attracted to the algae’s odour, but ingesting it could prove fatal, officials warn.

People or animals that drink contaminated water are at risk of headaches, fever, diarrhea, vomiting, cramps, muscle, joint pain, and liver damage. Children may experience more severe symptoms.

Provincial officials also suggested that if residents want to keep using surface water for a drinking water source, they should get the water tested. Officials say to ask a laboratory to test for the toxin microcystin, and if it is over the limit of 0.0015 milligrams/litre, residents should find a different source of drinking water.

Most municipal water supplies use specialized treatment to manage blue-green algae.


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  1. Ultrasonics can provide a safe and cost effective solution to control cyanobacteria blooms in lagoons, reservoirs, small and mid-size lakes. Ultrasound has been demonstrated world-wide to be safe and effective at controlling blooms and eliminating toxic microcystins in water. Currently two sewage lagoons in Ontario are benefitting from the use of ultrasound. This low power, dual band, multi-frequency solution does not cause lysing of cells and thus does not release toxins while also controlling the bloom. In 4 weeks in one test, total blue-green algae count was reduced from 14 million to 3 millions cells/mL. Ongoing treatment reduced the concentrations much further. Ultrasound at this power and frequency will not harm other phytoplankton and other aquatic species.


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