If you drive the Icefields Parkway highway through the Canadian Rockies, you’ll pass multiple turquoise-coloured lakes that are popular with tourists for taking photos.
The lakes get their iconic colour from rock flour, which is similar in appearance to baker’s flour used for making bread. Rock flour is made from glaciers grinding rocks into powder, which can take thousands of years.
The flour then flows into streams, rivers and lakes, becoming suspended in the water column, reflecting a turquoise colour.
But as glaciers retreat or disappear with climate change, less flour is produced, resulting in clearer lakes.
“They’ll resemble the lakes that we see in central Alberta,” said Rolf Vinebrooke, a freshwater ecologist at the University of Alberta.
Instead, the lakes will become a more sapphire blue, he said.
This change is already happening.
For example, Curator Lake and Geraldine Lakes in Jasper National Park have already become clearer.
“There’s a lot of unique biodiversity in these glacially fed Alpine lakes and streams that will get lost,” Vinebrooke said.
One unique species that could be at risk is a bright red copepod called Hesperodiaptomusarcticus, which is about the size of a pen tip.
“It [colour change] might not be a good thing for those particular species,” said Janet Fischer, a biology professor at Franklin and Marshall College in Pennsylvania.
As lakes become clearer, sunlight can penetrate deeper into the water, which fuels algal growth. Less glacier ice means warmer water, resulting in a more productive lake.
As the lakes warm, their environment may become more benign, said Fischer, allowing more widespread species to invade and potentially outcompete the unique ones, like Hesperodiaptomusarcticus.
Source: CBC
