Marl Lake - July 2024
Last weekend I was up at a lake nestled into the backcountry of Quebec. It’s a gorgeous example of a marl lake, defined by deposits of limestone and calcium carbonate. In fact one of the first videos I ever did for this project was a little preamble about these lakes in anticipation of a more in-depth video to come - which still hasn’t quite materialized two years later. But part of my goal in going back up was to fill in the gaps I needed for that in-depth one.
One of the most striking qualities of marl lakes is their colour, which can be downright mediterranean. It’s actually an effect of microscopic calcium carbonate sediments in the water column scattering the light and generally favouring the blue wavelengths. It’s the same principle we talked about in a video about bird colours, and the reason the sky is blue.
The resulting alkalinity of the water and the fact that the calcium carbonate tends to settle over everything (that’s the marl) means these lakes can tend to be pretty void of life. You’re left only with the plants and animals who can weather the extreme conditions, or rely mostly on nutrients at the shore.
In the case of this lake that included species of minnows, crayfish, freshwater clams, a sprinkling of water striders on the surface, not to mention some amphibians and reptiles - a toad who had found himself a high rise apartment in a tree hole and a juvenile snapping turtle who hung out under a dock.
Fingers crossed I’ve finally got enough to start working on the video properly!