Impact of meltwater flow intensity on the spatiotemporal heterogeneity of microbial mats in the McMurdo Dry Valleys, Antarctica

A Zoumplis; B Kolody; D Kaul; H Zheng; P Venepally; D M McKnight; C Takacs-Vesbach; A DeVries; A E Allen

doi:10.1038/s43705-022-00202-8

Impact of meltwater flow intensity on the spatiotemporal heterogeneity of microbial mats in the McMurdo Dry Valleys, Antarctica

ISME Commun. 2023 Jan 23;3(1):3. doi: 10.1038/s43705-022-00202-8.

Authors

A Zoumplis^{1

2}, B Kolody³, D Kaul², H Zheng², P Venepally², D M McKnight⁴, C Takacs-Vesbach⁵, A DeVries⁶, A E Allen^{7

8}

Affiliations

¹ Scripps Institution of Oceanography, University of California, San Diego, CA, USA.
² Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA, USA.
³ Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, USA.
⁴ Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA.
⁵ Department of Biology, University of New Mexico, Albuquerque, NM, USA.
⁶ Evolution, Ecology and Behavior, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
⁷ Scripps Institution of Oceanography, University of California, San Diego, CA, USA. aallen@ucsd.edu.
⁸ Microbial and Environmental Genomics Group, J. Craig Venter Institute, La Jolla, CA, USA. aallen@ucsd.edu.

Abstract

The meltwater streams of the McMurdo Dry Valleys are hot spots of biological diversity in the climate-sensitive polar desert landscape. Microbial mats, largely comprised of cyanobacteria, dominate the streams which flow for a brief window of time (~10 weeks) over the austral summer. These communities, critical to nutrient and carbon cycling, display previously uncharacterized patterns of rapid destabilization and recovery upon exposure to variable and physiologically detrimental conditions. Here, we characterize changes in biodiversity, transcriptional responses and activity of microbial mats in response to hydrological disturbance over spatiotemporal gradients. While diverse metabolic strategies persist between marginal mats and main channel mats, data collected from 4 time points during the austral summer revealed a homogenization of the mat communities during the mid-season peak meltwater flow, directly influencing the biogeochemical roles of this stream ecosystem. Gene expression pattern analyses identified strong functional sensitivities of nitrogen-fixing marginal mats to changes in hydrological activities. Stress response markers detailed the environmental challenges of each microhabitat and the molecular mechanisms underpinning survival in a polar desert ecosystem at the forefront of climate change. At mid and end points in the flow cycle, mobile genetic elements were upregulated across all mat types indicating high degrees of genome evolvability and transcriptional synchronies. Additionally, we identified novel antifreeze activity in the stream microbial mats indicating the presence of ice-binding proteins (IBPs). Cumulatively, these data provide a new view of active intra-stream diversity, biotic interactions and alterations in ecosystem function over a high-flow hydrological regime.

Abstract

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