Biology professor on how longer summers can spell doom for lakes

When you head out to a lake in Canada this summer, you may notice more algae covering the surface than usual. This is just one of the frightening effects our planet is warming on the world’s lakes right now, according to a biology professor.

It’s part of a pattern that will only increase with global warming, Queen’s University professor John Smol told CTV News Channel, painting a picture of lakes shrinking, others flooding, species endangered fish and algal blooms killing underwater plants. .

“We are sleepwalking into disaster,” he said on Sunday, saying we must act now to slow these changes. “I wouldn’t say it’s too, too late, but it’s very, very late.”

When people first hear that our summers are getting longer, at first “they think it’s great, he says.

But with this prolonged heat comes growing instability in ecosystems, including the more than 100 million lakes that exist around the world.

“One of the classic things for people who might be at their cabin this weekend, or soon, they’re probably going to start seeing more algal blooms, especially blue-green algal blooms – those are the scum on the surface of the lakes,” Smol said. . “They probably haven’t seen the ones that were fluent in the past.”

He explained that blue-green algae blooms, which are blooms of cyanobacteria, “can have serious health effects, not just for us, but for other organisms.”

Cyanobacteria thrive in warm water and can grow faster when temperatures rise, which means climate change can help create the ideal conditions for increased algal blooms.

These algal blooms can block sunlight for those living below the surface of the water, as well as consume oxygen that could otherwise nourish underwater plants, resulting in dead zones in our lakes. They can even make water toxic by leaching too much oxygen.

We have already seen the impact of a cyanobacterial bloom in one of the Great Lakes – the water supply in Toldeo, Ohio was interrupted for three days in 2014 by an algal bloom in the Lake Erie.

But the way climate change is affecting our lakes goes beyond algae.

“It’s just one of the things you can see visually,” Smol said. “A lot of fish habitats are badly affected, especially deep-sea fish that like cold water.”

Increased algal blooms, loss of natural habitats by cold-water fish, decreased winter ice cover and lower levels of dissolved oxygen in the water are all covered by a new study that looked at how climate change is affecting lakes.

Smol, along with experts from York University and Bangor University in Wales, reviewed current research on freshwater lakes around the world to create a cohesive picture.

The report, published in mid-July in the peer-reviewed journal BioScience, found that climate change is transforming our lakes in many ways, depending on where they are on the planet.

In Ontario, algal blooms have been reported in lakes as late as November, the study points out.

The study also found that global lake evaporation is expected to increase by 16% by the end of the century.

“In an area with more evaporation, water levels will drop,” Smol said. “If you’re in an area where there’s more runoff, let’s say you’re getting your water from high mountain areas that are being washed away by melting glaciers, well, right now you might be getting a lot of water. , even too much water.

“They’re like water towers, these glaciers in the mountains – once they melt, they slow down a bit and cut off a lot of the water supply.”

Loss of ice cover on lakes can also lead to higher salinity in the water itself, the study found, which impacts aquatic life.

Smol said the varying impacts of climate change on our lakes affect not only the plants and animals in the water, but also the cultural, recreational and economic activities of humans who live near that water.

“For many people, freshwater fish is a major source of protein, not just in Canada but around the world, and if some of your most valuable fish are being crowded out by this warming, that also comes into line. account for food security,” he said. .

These impacts are often felt most strongly by indigenous communities, who may depend on fishing and other water-related activities.

“The last thing many indigenous communities need is more water supply issues,” Smol said.

Our inaction on climate change is frustrating to scientists like Smol, who have said we haven’t prepared enough for our changing world.

“The fact that I’m still angry means I still have hope,” he said. “But it is very, very late.

“There have been some positive things adopted by different governments, but we have to move quickly and move in this direction. The longer we wait, the fewer options we have. And really, now, options for our grandchildren and great-grandchildren. There are more changes to come, and we need to prepare for them.

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