ALPALGA: The search for mountain snow microalgae

In glaciers, well above sea level, algae thrive. Normally invisible to the naked eye, they are often spotted by hikers trekking through the mountains in late spring as strikingly colored stretches of snow, in shades of ochre, orange and red. Known as "glacier blood," this coloring is the result of the punctual multiplication (or bloom) of the microalgae that inhabit the snow.