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Wetland loss a cause of algal blooms in Great Lakes, study finds

Experts predict more algae on lakes this year.

An algae bloom on Lake Erie off Toledo, Ohio, in 2014.

File / The Associated Press

An algae bloom on Lake Erie off Toledo, Ohio, in 2014.

The loss of our wetlands is partly responsible for the abundance of algae blooming in the Great Lakes, says a new study — and even more slime could be on the way.

"In the last 10 years or so, we have been seeing an increase in algal blooms," said Nandita Basu, associate professor of civil and environmental engineering at the University of Waterloo.

In a recent study published in the journal Water Resources Research, Basu and her colleague Fred Cheng report that Canada is losing huge swaths of wetland to agricultural activity and urban sprawl.

"Wetlands naturally filter the water before it goes to the lake, so we have been consistently losing that filter," explained Basu.

According to the study, over 70 per cent of the wetland once spanning Southern Ontario has been lost to development, leaving beachgoers and aquatic species at risk. The researchers urged communities near the Great Lakes to double down on water-protection efforts.

"Now is the time for water-treatment plants to really up their game to get any of those toxins out of the water," Basu said.

Experts predict this year will be especially bad for algal blooms, considering the enormous amount of rain, said Krystyn Tully, vice-president of advocacy group Lake Ontario Waterkeeper.

All that rain is sweeping nitrogen and phosphorous from fertilizers into bodies of water across the province, nourishing the algae. Tully said Lake Erie is the most polluted by agricultural runoff.

The most dangerous kind of algae is the blue-green variety, which looks like an oil slick on the water. The bacteria it contains can be fatal to animals and very harmful to humans. It was blue-green algae that forced Toledo, Ohio to shut down its drinking-water supply in 2014.

Tully said this variety is mostly seen in the Bay of Quinte near Belleville. They haven't seen it anywhere on Lake Ontario this year but fear it could still arrive.

People in urban areas have to be careful about the kind of fertilizers they use in their lawns and gardens, Tully said.

"In a heavy rain year like this one, any of that can end up directly into the closest lake," she said.

Tully urged residents to report anything suspicious to water-treatment organizations.

"You never want to wait until somebody's dog dies or something extreme happens."

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