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Seminar talk: Come the spring I’ll live again - A winter to summer transition of bacterial and archaeal communities in Arctic sea ice

Stefan Thiele is a postdoc in Marine Microbiology at the University of Bergen. He will give a seminar talk on November 8, 2021.

Portrett Stefan Thiele
Stefan Thiele


The Arctic is warming 2-3 times faster than the global average, leading to a decrease in arctic sea ice extent, thickness, and associated changes in sea ice structure. These physical changes impact sea ice habitat properties and the ice-associated ecosystems, including the timing, magnitude, and composition of the sea ice algae bloom. These blooms provide the bacterial and archaeal community with a plethora of algal derived carbon sources and thereby create a succession of ecological niches over the course of the bloom, leading to a correlated succession of the bacterial in archaeal community. Here we detail for the first time the transition of these communities in Arctic sea ice from winter through spring to early summer during the Norwegian young sea ICE (N-ICE2015) expedition in the Arctic sea ice pack north of Svalbard, Norway. The winter community was dominated by Gammaproteobacteria and Nitrosphaeria, more precisely amplicon sequence variants of the Candidatus Nitrosopumilus, which disappeared with the onset of the vernal sea ice algae bloom. In spring, the community shifted to a dominance of Gammaproteobacteria and Bacteroidia, as is commonly observed at lower latitudes during phytoplankton spring blooms. The increase of predicted carbohydrate-active enzymes in spring and summer, as compared to winter, indicating that carbon source availability is a strong driver of bacterial and archaeal community succession in arctic sea ice. This implies an annual succession from a Candidatus Nitrosopumilus dominated winter community to a Gammaproteobacteria and Bacteroidia dominated spring bloom community and onward into a long post bloom phase during summer, based on algal derived carbon sources.


Short biography:

I'm currently a postdoc in Marine Microbiology at the University of Bergen, where I focus on the analyses of microbial communities in arctic environments, such as sea water, sediments, sea ice, but also glacial springs and pingos. I use next generation sequencing and bioinformatics to describe the bacterial and archaeal communities and try to identify key players in these environments. The focus is always on the effects of climate change on the communities or vice versa.


Arranged date for the seminar talk: November 8, 2021. Venue: Bjerknes lecture room 4020, Jahnebakken 5.