Ice sheet beds host metabolically active microbial communities and serve as sites of methane production, consumption, and mineralisation. In a recent paper, we showed that microbially-derived methane is released from the western margin of the Greenland Ice Sheet (GrIS) at concentrations spanning five orders of magnitude (<0.4 nM to ~50,000 nM), indicating a strong gradient in its availability.

In a new paper led by Lia, we follow up on this by testing the significance of methane as a determinant of microbial assemblage structure along the GrIS’s western margin by serving as an important carbon and energy source. We used the samples of glacial runoff from the ~2,000-km transect and characterised their microbial assemblages using 16S rRNA amplicon sequencing.

Our analysis identified methane concentration as the strongest predictor of microbial assemblage structure and revealed a coupling between organisms involved in complex organic matter degradation and methane cycling, suggesting microbial interactions linking methanogenic and methanotrophic processes. Our results suggest that methane exerts a strong deterministic influence on microbial assembly at the GrIS margin and highlight the role of these ecosystems in carbon cycling and methane dynamics in a warming Arctic.

The research was supported by the Czech Ministry of Education as part of the ERC-CZ programme (project LL2004 ‘MARCH₄G’ to Marek).

Wentzel LCP, Klímová P, Kohler TJ, Hatton JE, Stehrer-Polášková A, Žárský JD, Trubač J, Píka PA, Hawkings JR, Doting EL, Murphy JG, Stibal M (2026) Methane is an important selection factor in microbial community assembly along the Greenland Ice Sheet margin. Applied and Environmental Microbiology doi:10.1128/aem.00875-26