The lakes of Plan des Eaux and Pys

If you come across these small mountain lakes in the summer with their peaceful waters, you’ll find it hard to imagine that a whole life grows there according to an annual cycle. At the end of autumn, the surface of the lake freezes over from the ice and snow. Its thickness increases and deprives the body of water of dissolved oxygen, essential to life. The lake will only resume its nurturing role when the ice-pack breaks down during the short summer. It is then that life suddenly resumes for the plankton, the dipteran larvae, the dragonflies, the damselflies, the common frog, and more rarely the introduced salmonids such as brown trout or arctic char.