Investigating microbial habitats and carbon pools associated with a high Arctic glacier

  • Author / Creator
    Dhoonmoon, Charvanaa
  • Glacial systems are reservoirs of nutrients, labile organic matter, and microbes. Glaciers contain diverse environments (supraglacial (surface), subglacial (base), and ice-marginal) with variable organic matter pools shaped by different physical processes and site-specific microbial communities and metabolisms. The ecological interactions between organic matter and microbial communities, including the bioavailability of organic matter to these communities, in glacial environments remain to be constrained. Samples of supraglacial ice, meltwaters from an ice-marginal channel, and basal ice were collected from Sverdrup Glacier, a polythermal tidewater glacier in the Canadian high Arctic. We assessed microbial diversity (from the 16S rRNA gene) and functional potential (from taxonomy) and correlated community composition with solute (nutrient and major ions) concentrations and dissolved organic matter (DOM) composition measured via fluorescence spectroscopy and ultra-high resolution mass spectrometry (FT-ICR-MS). We also incubated melted debris-rich and debris-poor basal ice to monitor microbial uptake of glacial organic carbon to gain insight into the lability of this carbon pool and the effects on microbial diversity and functional potential. Distinct microbial communities and different patterns of correlations with solute and DOM properties among the glacial environments suggest that site-specific compositions of solutes and DOM shape community structures. The presence of both putative heterotrophic and autotrophic metabolisms across these glacial environments further supported the potential for in-situ microbial carbon cycling in glacial ecosystems. Fluorescence spectroscopy and FT-ICR-MS results revealed significant but varying labile fractions of DOM among the glacial environments, largely derived from in-situ microbial activity. Our experimental incubations showed that this DOM was bioavailable to in-situ microbial communities and stimulated glacial heterotrophs in both incubations. A higher carbon uptake was also observed in the debris-rich incubation versus the debris-poor incubation, suggesting a differential supply of labile DOM by debris in basal ice. This study helps to establish a baseline from which to assess future physical and ecological changes in glacial labile DOM reservoirs and microbe-DOM interactions driven by climate warming. As glaciers shrink and glacial meltwater and associated labile carbon fluxes increase, this study provides insight into the role of in-situ microbial communities in shaping DOM bioavailability and the effect of DOM on glacial microbial community ecology.

  • Subjects / Keywords
  • Graduation date
    Spring 2022
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.