Ecology of microalgae on tropic glaciers and in slushy snow

Extremophilic microalgae exclusively living in melting snow and on wet glacier surfaces are primary producers of ecosystems with harsh abiotic conditions. They developed a plethora of morphological, metabolic and molecular mechanisms to cope with low temperatures or exposure to extreme visible and ultraviolet irradiance. While snow algae of the Chlorophyceae causing green to red discolorations have been studied well in the last decades, two different phenomena still deserve attention: First, equatorial tropic glaciers in South America with recently discovered populations of unknown streptophytic algae (Zygnematophyceae), which darken the ice surface due to their pigmentation. The cells are different to what is known from polar and mid-latitude glaciers. Second, golden-brown snow slush caused by unicellular Chrysophyceae related to Hydrurus, which are hardly understood. Arctic blooms are characteristic for remarkable large populations that appear in short time. Both habitats will be ecophysiologically investigated to understand how cells sustain the prevailing conditions. Preliminary data of the applicants indicate the presence of several snow and glacial algae new to science, which could also be of biotechnological interest. Tropical glaciers developed a distinct eukaryotic cryoflora, adapted to the specific local conditions of a diurnal climate cycle. The aim is to assess this habitat for the first time for demonstrating physiologic and taxonomic differences to non-tropic glaciers. Likewise, the diversity and metabolism of chrysophytes causing golden-brown slush will be investigated to understand the high productivity and principal stress response mechanisms. Field populations will be surveyed for primary productivity, community diversity, the transcriptome, presence of key metabolites like pigments or compatibles solutes, and the cell architecture. Lab strains will be studied for life cycles and testing physiologic optima. The methods used include chlorophyll fluorometry, radio-nucleotide uptake, metagenomics by Illumina amplicon high-throughput- sequencing, analytical screening of organic extracts by chromatographic protocols, light- and electron microscopy. The phototrophic eukaryotes unique to tropical glacier surfaces have never been investigated before, and are extremely endangered to be extinct as these exotic habitats will disappear due to global warming. Likewise, Chrysophyceae abundantly causing tinted slush have been almost scientifically neglected so far, despite they play a significant role in otherwise low-productive terrestrial polar ecosystems.