Abstrakt
Natural environments covered with snow or ice are home to still poorly characterized microbial life. Photosynthetic organisms play a key role in colonizing these thermally labile habitats and creating conditions for complex communities to develop.
The duration of these cold-adapted microbial communities can range from a few months to permanent settlements depending on the complete or partial melting of the snow and ice cover. In such habitats, algae do not only cope with low temperatures (psychrotolerance and psychrophily), but they can also be subjected to high and variable light levels, UV irradiance, low levels of nutrients (oligotrophy), and a variety of other abiotic stresses.
In some cases, bloom-forming algae cause the formation of "green snow." More often, they accumulate pigments, such as the carotenoid astaxanthin, leading to the development of "orange," "pink," or "red snow." The abundance of pigmentedmicroalgae lowers the albedo and accelerates melting. Algae are therefore both "markers" (positively impacted by current environmental changes) and "actors" (positively acting on ice and snowmelt) of climate change.
Research on ice and snow algae is thus essential to better address the impact of climate change in polar and mountain environments.