ALPALGA is a unique collaborative project in Europe, associating on the Grenoble site scientists from several disciplines, including biologists, environment scientists (ecology) and glaciologists to study the microalgae that inhabit ecosystems from 1000 to 3000 meters above sea level, where there exploration is still challenging, the Alpine mountains.
Microalgae are sometimes visible when they multiply to the point that they stain in gree a piece of water, the wet trunk of a tree, or the dry surface of a rock.
In snow, microalgae can stain the surface in green, but most often, they become loaded with pigments that protect them from strong light, then staining the snow surface in red or orange. The appearance of “red snows”, already known in the Antiquity, seems to be more and more frequent at high altitudes, as well as in the Arctic and Antarctic regions.
But where are microalgae when we cannot see them, where do they come from? Where do they go when the snow has melted?