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Contributed Talk

Session: : Arctic, Alpine, Antarctic Systems

COS 205-1 - Best predictors of supraglacial pool microbial community structure on a debris covered glacier in Tibet

Wednesday, August 9, 2023
3:30 PM – 3:45 PM PDT
Location: B111

    Presenting Author(s)

  • Heather L. Fair, Ph.D.

    National Science Foundation NSF Postdoc
    University of Minnesota College of Biological Sciences
    Columbus, Ohio, United States

    Slides (PDF)

    • Coauthor(s)

  • PS

    Peter C. Smiley, Jr., Ph.D.

    Research Ecologist
    United States Department of Agriculture, United States

  • TH

    Trinity Hamilton

    University of Minnesota College of Biological Sciences, United States

  • QL

    Qiao Liu

    Chinese Academy of Sciences Institute of Mountain Hazards and Environment, China (People's Republic)

Abstract: Meltwater habitats (i.e., supraglacial pools, proglacial streams, cryoconite holes, etc.) are prevalent on debris-covered mountain glaciers as a result of climate warming and enhanced debris transport driven by melt-processes. Yet, less information is available on the microbial ecology of meltwater habitats of debris-covered glaciers than that of clean ice surface glaciers in the Arctic and Antarctica. Our research objective was to understand the microbial community structure and its relationships with abiotic and biotic factors in supraglacial pools on a debris-covered glacier in Tibet. Our research questions were: 1) what microbes occur within the sediments of supraglacial pools?; 2) which abiotic and biotic habitat variables have the most influence on the microbial community structure?; and 3) does microbial taxa composition of supraglacial pools differ from that of glacial-melt stream pools? We collected microbial samples, invertebrates, and measured 22 abiotic and biotic environmental predictor variables from 46 supraglacial pools and nine glacial-melt stream pools in 2018 and 2019. Bacterial taxa were identified with 16S rRNA sequencing. Generalized linear model analyses and the small sample Akaike information criterion scores (AICc) and variable importance scores were used to identify the best predictor variables of microbial community structure. Multi-response Permutation Procedure was used to compare taxa composition between supraglacial pools and stream pools.

The five most abundant phyla in supraglacial pools were Proteobacteria (29.63%), Actinobacteria (19.92%), Bacteroidota (13.42%) and Cyanobacteria (7.64%). Total amplicon sequence variant abundance, Hill species richness, Hill Shannon diversity index, Hill Simpson, and Cyanobacteria abundance were best predicted by Chironomidae larvae abundance. Gammaproteobacteria and Archaea abundance were best predicted by turbidity.

Taxa composition was best predicted by year. All of the best identified predictor variables had AICc scores that were at least 3.6 AICc units less than their corresponding null model (i.e., intercept-only model) and exhibited the greatest variable importance scores. Multi-response Permutation Procedure indicated that there was no difference (P = 0.5315, A = -0.0035) between the microbial species composition between supraglacial pools and stream pools.

None of the physico-chemical parameters we anticipated would be important in shaping bacterial community structure of supraglacial pools were identified as such (e.g., pool depth, conductivity). However, Chironomidae larvae were an important predictor variable, and they may play a much larger role in shaping the biodiversity and abundance of bacterial communities of pools than anticipated. More research is needed on environmental, eukaryotic, bacterial, and fungal community interactions of debris-covered glacier pools.