Snow algae and glacier ice algae biogeography and ecophysiology
Affiliation
Charles University, Faculty of Science, Department of Ecology, Viničná 7, Prague 2, Czech Republic
Abstract
Long-lasting, melting snowpacks in sub/polar, alpine and forested regions provide a habitat for specialized microalgae thriving in the water film between ice crystals. These photoautotrophs are exposed to low temperatures, extreme high-light, UV irradiation conditions and repeated freeze-thaw cycles.
The main representatives of snow algae belong to the green algal order Chlamydomonadales. Massive occurrence of these cells causes reddish, orange or green snow colorations. Their survival depends on the timing of life cycle changes and specialised metabolite production. While some taxa are cosmopolitan, others have limited geographical distribution. Species at elevations are endangered by earlier snow melt and reduced snow precipitation.
The second algal group common in melting snowpacks belongs to the golden-brown algal order Hydrurales, with several newly described species that use polyols as antifreeze agents. The most prominent glacial ice algae belong to the Zygnematales — the closest known relatives of land plants. These algae cause dark to pinkish coloration of glaciers. Filamentous Ancylonema nordenskioldii produces ice binding proteins to prevent ice recrystallization; dark vacuoles provide UV and visible light screening. Using Raman spectroscopy, we show the alga sequesters iron and forms organic metal complexes. Single-celled Ancylonema alaskanum is common in the European Alps while its filamentous sister species dominates the Arctic.
Keywords: snow, glacier, algae, haplotypes, photosynthesis, pigments, fatty acids