Algae bloom closes part of Lake Micmac to people, dogs

An algae bloom along the shore of Lake Micmac at Shubie Park in Dartmouth, N.S., has closed the area to swimming.

People and pets shouldn't be in the water in that part of the park because algae blooms may produce toxins that can cause mild to severe health problems, says Cameron Deacoff, an environmental performance officer with the municipality.

The designated off-leash area is popular with dog owners.

"In freshwater environments, there are different types of algae that can produce toxins that are harmful to both humans and pets," he said Thursday.

He said blue-green algae, also called cyanobacteria, most commonly causes blooms.

"The biggest concern is that many of the species of blue-green algae that produce toxins can be harmful to people and animals, wildlife and livestock, and the symptoms that can be experienced range from relatively mild to quite severe ... death. It is important to note that is relatively rare."

Concerns about life-threatening symptoms

Earlier this month, three dogs died after swimming in the St. John River in Fredericton. A New Brunswick veterinarian said he suspected blue-green algae was a cause of the deaths.

While that has not been confirmed, "concerns about blue-green algae blooms is still quite relevant," Deacoff said.

Respiratory, nervous system and rapid onset liver damage are the more severe effects.

However, more benign symptoms, such as headache, nausea, diarrhea, fever, dizziness and sore throat, are much more common, Deacoff said.

Those symptoms can also be produced by bacteria, such as E. coli, which also closes some beaches in the summer, but the algae toxins are more dangerous because of the possible escalation to a life-threatening condition.

Heat wave contributing to blooms

The current heat wave has raised water temperatures producing algae blooms unlikely to be seen until mid-to-late August and into September, Deacoff said.

"These algae cells are natural inhabitants of our waterways and are there all the time, but they don't often bloom. Certainly we have relatively little experience with that in Nova Scotia, although not none," he said.

"I think the reason the city has put a little bit more emphasis on this is due to the greater prevalence of freshwater blooms in recent years." 

Longer daylight hours, wind and water currents and pH levels also contribute to the blooms.

Not all algae blooms are of the blue-green type. But Deacoff advises people to steer clear of areas where there is a bloom.

Pets and children, because of their lower body weights and propensity to ingest water, should be kept away.

"it's better to play it safe and simply avoid the area, certainly until after the bloom has dissipated," he said.

"It would be better to avoid the area in general because, unless the water is tested, it's uncertain whether or not toxins have been produced and toxins do not dissipate at the same time blooms do. They persist longer."