The distinctive weathering crust habitat of a High Arctic glacier comprises discrete microbial micro‐habitats

• Published in: Environmental microbiology Vol. 26; no. 4; pp. e16617 - n/a
• Main Authors: Rassner, Sara M. E., Cook, Joseph M., Mitchell, Andrew C., Stevens, Ian T., Irvine‐Fynn, Tristram D. L., Hodson, Andrew J., Edwards, Arwyn
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.04.2024; Wiley Subscription Services, Inc
• Subjects: Arctic glaciers; Arctic Regions; Bacteria - genetics; Biogeochemical cycle; Biogeochemical cycles; Catchment area; Ecosystems; Gene sequencing; Glaciation; Glacier melting; Glaciers; Habitats; Ice; Ice Cover - microbiology; Ice formation; Ice sheets; Meltwater; Metagenomics; Microbial activity; Microbiomes; Microbiota - genetics; Microorganisms; Pore water; Porous media; RNA, Ribosomal, 16S - genetics; rRNA 16S; Snowmelt; Sunlight; Weathering; Arctic Regions
• ISSN: 1462-2912; 1462-2920
• DOI: 10.1111/1462-2920.16617

Sunlight penetrates the ice surfaces of glaciers and ice sheets, forming a water‐bearing porous ice matrix known as the weathering crust. This crust is home to a significant microbial community. Despite the potential implications of microbial processes in the weathering crust for glacial melting, biogeochemical cycles, and downstream ecosystems, there have been few explorations of its microbial communities. In our study, we used 16S rRNA gene sequencing and shotgun metagenomics of a Svalbard glacier surface catchment to characterise the microbial communities within the weathering crust, their origins and destinies, and the functional potential of the weathering crust metagenome. Our findings reveal that the bacterial community in the weathering crust is distinct from those in upstream and downstream habitats. However, it comprises two separate micro‐habitats, each with different taxa and functional categories. The interstitial porewater is dominated by Polaromonas, influenced by the transfer of snowmelt, and exported via meltwater channels. In contrast, the ice matrix is dominated by Hymenobacter, and its metagenome exhibits a diverse range of functional adaptations. Given that the global weathering crust area and the subsequent release of microbes from it are strongly responsive to climate projections for the rest of the century, our results underscore the pressing need to integrate the microbiome of the weathering crust with other communities and processes in glacial ecosystems. The weathering crust microbiome of a High Arctic glacier inhabits two discrete habitats, with distinctive populations of highly adapted microbes in the ice and melt, respectively.