High Arctic lake ice was typically perennial, making it a stable habitat for unique microbial psychrophilic organisms. However, warming has disrupted the stability of this unique habitat, as evidenced by the first recorded ice off events that occurred on Ward Hunt Lake (83N) in 2011. Microbial assemblages in perennial lake ice are therefore especially vulnerable to further warming in the Arctic, and since little is known on how lake ice microbes contribute to energy cycling in freshwater systems, it is unclear how they will adapt to variable seasonal ice conditions. Our objective is to describe the microbial assemblages of Ward Hunt Lake ice. Ice cores were collected in July 2022, from which we extracted nucleic acids for next-generation sequencing. Amplicon sequencing of the 16S rRNA gene revealed the presence of a diverse bacterial community including Proteobacteria, Bacteroidota, Actinobacteriota and Cyanobacteria which varied in composition by ice strata, and differed from the underlying water column. Deep shotgun metagenomic sequencing was also used to investigate the functional and metabolic potential of microbes, with special attention to pathways associated with psychrophily, including nutrient utilization (oligotrophy), cold-shock proteins (cold), and genome repair (UV resistance). These data provide a unique portrait of the microbial inhabitants of lake ice in an area subjected to warming conditions and give insight into the metabolic pathways present in the ice, furthering our understanding of the ways in which life in lake ice may change in the future.

Primary Presenter: Maxime Larose, Université du Québec à Chicoutimi (maxime.larose2@uqac.ca)

Authors:

Maxime Larose, Université du Québec à Chicoutimi (UQAC)  (maxime.larose2@uqac.ca)

Catherine Girard, Université du Québec à Chicoutimi (UQAC)  (catherine5_girard@uqac.ca)