Patterns in microbial assemblages exported from the meltwater of Arctic and sub-Arctic glaciers

Kohler, T. J., Vinšová, P., Falteisek, L., Yde, J. C., Hatton, J. E., Hawkings, J. R., Lamarche-Gagnon, G., Hood, E., Cameron, K. and Stibal, M. (2020) Patterns in microbial assemblages exported from the meltwater of Arctic and sub-Arctic glaciers. Frontiers in Microbiology, 11, 669. (doi: 10.3389/fmicb.2020.00669) (PMID:32351489) (PMCID:PMC7174618)

Abstract

Meltwater streams connect the glacial cryosphere with downstream ecosystems. Dissolved and particulate matter exported from glacial ecosystems originates from contrasting supraglacial and subglacial environments, and exported microbial cells have the potential to serve as ecological and hydrological indicators for glacial ecosystem processes. Here, we compare exported microbial assemblages from the meltwater of 24 glaciers from six (sub)Arctic regions – the southwestern Greenland Ice Sheet, Qeqertarsuaq (Disko Island) in west Greenland, Iceland, Svalbard, western Norway, and southeast Alaska – differing in their lithology, catchment size, and climatic characteristics, to investigate spatial and environmental factors structuring exported meltwater assemblages. We found that 16S rRNA gene sequences of all samples were dominated by the phyla Proteobacteria, Bacteroidetes, and Actinobacteria, with Verrucomicrobia also common in Greenland localities. Clustered OTUs were largely composed of aerobic and anaerobic heterotrophs capable of degrading a wide variety of carbon substrates. A small number of OTUs dominated all assemblages, with the most abundant being from the genera Polaromonas, Methylophilus, and Nitrotoga. However, 16–32% of a region’s OTUs were unique to that region, and rare taxa revealed unique metabolic potentials and reflected differences between regions, such as the elevated relative abundances of sulfur oxidizers Sulfuricurvum sp. and Thiobacillus sp. at Svalbard sites. Meltwater alpha diversity showed a pronounced decrease with increasing latitude, and multivariate analyses of assemblages revealed significant regional clusters. Distance-based redundancy and correlation analyses further resolved associations between whole assemblages and individual OTUs with variables primarily corresponding with the sampled regions. Interestingly, some OTUs indicating specific metabolic processes were not strongly associated with corresponding meltwater characteristics (e.g., nitrification and inorganic nitrogen concentrations). Thus, while exported assemblage structure appears regionally specific, and probably reflects differences in dominant hydrological flowpaths, OTUs can also serve as indicators for more localized microbially mediated processes not captured by the traditional characterization of bulk meltwater hydrochemistry. These results collectively promote a better understanding of microbial distributions across the Arctic, as well as linkages between the terrestrial cryosphere habitats and downstream ecosystems.

• Item Type: Articles
• Additional Information: This research was supported by a Czech Science Foundation Grant to MS (GAˇCR 18-12630S). Field work was additionally supported by a Charles University Foundation Grant to JŽ (GAUK 279715) and a Research Council of Norway Arctic Field Grant to TK (RiS ID 10410) and PV (RiS ID 10645). TK was further supported by Charles University Research Centre Program No. 204069, JY by the Joint Programming Initiative (JPI-Climate) award #71126, and JRH by the European Union Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Actions Fellowship ICICLES (Grant Agreement #793962).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Cameron, Dr Karen
• Authors: Kohler, T. J., Vinšová, P., Falteisek, L., Yde, J. C., Hatton, J. E., Hawkings, J. R., Lamarche-Gagnon, G., Hood, E., Cameron, K., and Stibal, M.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Frontiers in Microbiology
• Publisher: Frontiers
• ISSN: 1664-302X
• ISSN (Online): 1664-302X
• Copyright Holders: Copyright © 2020 The Authors
• First Published: First published in Frontiers in Microbiology 11:669
• Publisher Policy: Reproduced under a Creative Commons License