Glacier recession is creating new water bodies in proglacial forelands worldwide, including Antarctica. Yet, it is unknown how microbial communities of recently formed "young" waterbodies (originating decades to a few centuries ago) compare with established "old" counterparts (millennia ago). Here, we compared benthic microbial communities of different lake types on James Ross Island, Antarctic Peninsula, using 16S rDNA metabarcoding and light microscopy to explore bacterial and diatom communities, respectively. We found that the older lakes host significantly more diverse bacterial and diatom communities compared to the young ones. To identify potential mechanisms for these differences, linear models and dbRDA analyses suggested combinations of water temperature, pH, and conductivity to be the most important factors for diversity and community structuring, while differences in geomorphological and hydrological stability, though more difficult to quantify, are likely also influential. These results, along with an indicator species analysis, suggest that physical and chemical constraints associated with individual lakes histories are likely more influential to the assembly of the benthic microbial communities than lake age alone. Collectively, these results improve our understanding of microbial community drivers in Antarctic freshwaters, and help predict how the microbial landscape may shift with future habitat creation within a changing environment.

• Klíčová slova
• 16S rDNA, climate change, cryosphere, cyanobacteria, diatom, glacier,
• MeSH
• Bacteria genetika   MeSH
• jezera mikrobiologie   MeSH
• mikrobiota * MeSH
• rozsivky * genetika   MeSH
• voda MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Antarktida MeSH
• Názvy látek
• voda MeSH

The aim of this study was to assess the phylogenetic relationships, ecology and ecophysiological characteristics of the dominant planktic algae in ice-covered lakes on James Ross Island (northeastern Antarctic Peninsula). Phylogenetic analyses of 18S rDNA together with analysis of ITS2 rDNA secondary structure and cell morphology revealed that the two strains belong to one species of the genus Monoraphidium (Chlorophyta, Sphaeropleales, Selenastraceae) that should be described as new in future. Immotile green algae are thus apparently capable to become the dominant primary producer in the extreme environment of Antarctic lakes with extensive ice-cover. The strains grew in a wide temperature range, but the growth was inhibited at temperatures above 20 °C, indicating their adaptation to low temperature. Preferences for low irradiances reflected the light conditions in their original habitat. Together with relatively high growth rates (0.4-0.5 day-1) and unprecedently high content of polyunsaturated fatty acids (PUFA, more than 70% of total fatty acids), it makes these isolates interesting candidates for biotechnological applications.

• Klíčová slova
• Antarctica *, Ecology *, Fatty acids *, Ice-covered lakes *, Light *, Monoraphidium *, Phylogeny *, Temperature *,
• MeSH
• biodiverzita * MeSH
• Chlorophyta klasifikace   genetika   metabolismus   MeSH
• fytoplankton klasifikace   genetika   izolace a purifikace   metabolismus   MeSH
• fyziologická adaptace MeSH
• jezera MeSH
• ledový příkrov * MeSH
• nenasycené mastné kyseliny metabolismus   MeSH
• RNA ribozomální 18S genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Antarktida MeSH
• Názvy látek
• nenasycené mastné kyseliny MeSH
• RNA ribozomální 18S MeSH