Preprints
https://doi.org/10.5194/tc-2022-68
https://doi.org/10.5194/tc-2022-68
 
11 Apr 2022
11 Apr 2022
Status: this preprint is currently under review for the journal TC.

Variation in bacterial composition, diversity, and activity across different subglacial basal ice types

Shawn M. Doyle1 and Brent C. Christner2 Shawn M. Doyle and Brent C. Christner
  • 1Department of Oceanography, Texas A&M University, College Station, TX, 77843, USA
  • 2Department of Microbiology and Cell Science, University of Florida, Gainesville, FL, 32611, USA

Abstract. Glaciers and ice sheets possess layers of basal ice characterized by high amounts of entrained debris that can serve as sources of nutrients and organic matter, providing habitat for microorganisms adapted to the frozen conditions. Basal ice forms through various mechanisms and is classified based on its ice and debris content; however, little is known about variation in microbial composition, diversity, and activity across different basal ice types. We investigated these parameters in four different types of basal ice from a cold-based and temperate glacier and used a meta-analysis to compare our findings with microbiome studies from other frozen environments. We found basal ice environments harbor a diverse range of microbiomes whose composition and activity can vary significantly between basal ice types, even within adjacent facies from the same glacier. In some debris-rich basal ices, elevated ATP concentrations, isotopic gas signatures, and high ratios of amplified sequences for 16S rRNA relative to that for 16S rRNA genes implicated certain bacterial taxa (e.g., Paenisporosarcina, Desulfocapsa, Syntrophus, Desulfosporosinus) as being potentially active, with ice temperature appearing to be an important predictor for the diversity of taxa inferred to be active. Compared to those of other sympagic environments, these microbiomes often resembled those found in permafrost or perennial cave ice rather than other glacial ice environments. In contrast, debris-poor basal ices harbored microbiomes more like those found in oligotrophic englacial ice. Collectively, these results suggest that different basal ice types contain distinct microbiomes that are actively structured by the diagenesis of their habitat.

Shawn M. Doyle and Brent C. Christner

Status: open (until 15 Jun 2022)

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Shawn M. Doyle and Brent C. Christner

Shawn M. Doyle and Brent C. Christner

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Short summary
Here we compare the microbiomes of different types of basal ice within the same glacier. We also perform a meta-analysis that provides a broad overview of the specific microbial lineages enriched in different types of basal ice, glacial ice, permafrost, and cave ice. Combined, our findings provide exciting new insights into the microbiology of the cryosphere and fundamentally extend understanding of the limits of microbial life inside ice.