Comparison of Microphototrophic Communities Living in Different Soil Environments in the High Arctic

The Arctic region undergoes rapid climate change resulting in soil warming with
consequent changes in microbial community structure. Therefore, it is important to gain
more knowledge on the pioneer photosynthetic microorganisms and their relations to
environmental factors. Here we provide a description of the community composition
of microbial phototrophs in three different types of soils in the High Arctic (Svalbard):
vegetated soil at a raised marine terrace, biological soil crust (BSC) at high elevation,
and poorly-developed BSC in a glacier foreland. The studied sites differed from each
other in microclimatic conditions (soil temperature and soil water content), soil chemistry
and altitude. Combining morphological (cell biovolume) and molecular methods (NGS
amplicon sequencing of cyanobacterial 16S rRNA and eukaryotic 18S rRNA sequences
of isolates), we studied the diversity and biovolume of cyanobacteria and eukaryotic
microalgae. The results showed that cyanobacteria prevailed in the high altitude BSC
as well as in pioneering BSC samples in glacier foreland though with lower biomass.
More specifically, filamentous cyanobacteria, mainly Leptolyngbya spp., dominated the
BSCs from these two localities. In contrast, coccoid microalgae (green and yellow-green
algae) had higher biovolume in low altitude vegetated soils. Thus, the results of this study
contribute to a better understanding of microphototrophic communities in different types
of Arctic soil environments.