Dark ice in a warming world: advances and challenges in the study of Greenland Ice Sheet's biological darkening

Halbach, Laura; Chevrollier, Lou-Anne; Cook, Joseph M.; Stevens, Ian Thomas; Hansen, Martin; Anesio, Alexandre M.; Benning, Liane G.; Tranter, Martyn

doi:10.1017/aog.2023.17

Cited by 6 publications

(3 citation statements)

References 60 publications

(40 reference statements)

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“…It has recently been suggested that microbes—and especially bacteria—can be transported through the weathering crust, for instance from and into cryoconite holes (Cook et al 2016 ), in particular considering that surface meltwaters consistently contain about 10 4 cells ml −1 (Stevens et al 2022 ). The controls on transport of microbial cells through the weathering crusts remains, however, one of the outstanding questions (Halbach et al 2023 ). The standing theory for inoculation of the supraglacial environments by bacteria is that they are delivered through aerial deposition (Šantl-Temkiv et al 2018 , Cameron et al 2020 ).…”

Section: Discussionmentioning

confidence: 99%

Exploring microbial diversity in Greenland Ice Sheet supraglacial habitats through culturing-dependent and -independent approaches

Jaarsma,

Sipes,

Zervas

et al. 2023

FEMS Microbiology Ecology

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The microbiome of Greenland Ice Sheet supraglacial habitats is still under-investigated, and as a result there is a lack of representative genomes from these environments. In this study, we investigated the supraglacial microbiome through a combination of culturing-dependent and -independent approaches. We explored ice, cryoconite, biofilm, and snow biodiversity to answer: 1) how microbial diversity differs between supraglacial habitats, 2) if obtained bacterial genomes reflect dominant community members, and 3) how culturing versus high throughput sequencing changes our observations of microbial diversity in supraglacial habitats. Genomes acquired through metagenomic sequencing (133 high-quality MAGs) and whole genome sequencing (73 bacterial isolates) were compared to the metagenome assemblies to investigate abundance within the total environmental DNA. Isolates obtained in this study were not dominant taxa in the habitat they were sampled from, in contrast to the obtained MAGs. We demonstrate here the advantages of using metagenome SSU rRNA genes to reflect whole-community diversity. Additionally, we demonstrate a proof-of-concept of the application of in situ culturing in a supraglacial setting.

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Section: Discussionmentioning

confidence: 99%

Exploring microbial diversity in Greenland Ice Sheet supraglacial habitats through culturing-dependent and -independent approaches

Jaarsma,

Sipes,

Zervas

et al. 2023

FEMS Microbiology Ecology

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“…Under climatic warming, increased exposure of snow-free glacial ice and melt intensity (Rounce et al, 2023) will expand the extent of the weathering crust over the coming 30 to 50 years (Stevens et al, 2022). Hence, our limited appreciation of the weathering crust's microbiome presents critical lacunae in our knowledge of supraglacial ecosystems, their biogeochemical cycles and impacts on downstream ecosystems expanding as glaciers recede (Halbach et al, 2023;Hotaling et al, 2017;Irvine-Fynn & Edwards, 2013;Varliero et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

The distinctive weathering crust habitat of a High Arctic glacier comprises discrete microbial micro‐habitats

Rassner,

Cook,

Mitchell

et al. 2024

Environmental Microbiology

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Sunlight penetrates the ice surfaces of glaciers and ice sheets, forming a water‐bearing porous ice matrix known as the weathering crust. This crust is home to a significant microbial community. Despite the potential implications of microbial processes in the weathering crust for glacial melting, biogeochemical cycles, and downstream ecosystems, there have been few explorations of its microbial communities. In our study, we used 16S rRNA gene sequencing and shotgun metagenomics of a Svalbard glacier surface catchment to characterise the microbial communities within the weathering crust, their origins and destinies, and the functional potential of the weathering crust metagenome. Our findings reveal that the bacterial community in the weathering crust is distinct from those in upstream and downstream habitats. However, it comprises two separate micro‐habitats, each with different taxa and functional categories. The interstitial porewater is dominated by Polaromonas, influenced by the transfer of snowmelt, and exported via meltwater channels. In contrast, the ice matrix is dominated by Hymenobacter, and its metagenome exhibits a diverse range of functional adaptations. Given that the global weathering crust area and the subsequent release of microbes from it are strongly responsive to climate projections for the rest of the century, our results underscore the pressing need to integrate the microbiome of the weathering crust with other communities and processes in glacial ecosystems.

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“…These microbial blooms, dominated by the pigmented algae Ancylonema alaskanum and Ancylonema nordenskiöldii (Lutz et al, 2018;Proch azkov a et al, 2021) have a significant effect on the darkening of the Greenland Ice Sheet (Ryan, 2017(Ryan, , 2018Stibal et al, 2017;Uetake et al, 2010;Yallop et al, 2012). Controls on the development, spatial extent, and density of microbial blooms on bare ice surfaces remain poorly understood, causing large uncertainties in how microbial coverage of bare ice surfaces might change as snowlines retreat upwards due to climatic warming (Halbach et al, 2023;Ryan et al, 2019). Previous work has demonstrated that the availability of liquid water, light, and nutrients is essential for the development of these darkening algal blooms (Anesio et al, 2017;Holland et al, 2019;McCutcheon et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

The exometabolome of microbial communities inhabiting bare ice surfaces on the southern Greenland Ice Sheet

Doting,

Jensen,

Peter

et al. 2024

Environmental Microbiology

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Microbial blooms colonize the Greenland Ice Sheet bare ice surface during the ablation season and significantly reduce its albedo. On the ice surface, microbes are exposed to high levels of irradiance, freeze–thaw cycles, and low nutrient concentrations. It is well known that microorganisms secrete metabolites to maintain homeostasis, communicate with other microorganisms, and defend themselves. Yet, the exometabolome of supraglacial microbial blooms, dominated by the pigmented glacier ice algae Ancylonema alaskanum and Ancylonema nordenskiöldii, remains thus far unstudied. Here, we use a high‐resolution mass spectrometry‐based untargeted metabolomics workflow to identify metabolites in the exometabolome of microbial blooms on the surface of the southern tip of the Greenland Ice Sheet. Samples were collected every 6 h across two diurnal cycles at 5 replicate sampling sites with high similarity in community composition, in terms of orders and phyla present. Time of sampling explained 46% (permutational multivariate analysis of variance [PERMANOVA], pseudo‐F = 3.7771, p = 0.001) and 27% (PERMANOVA, pseudo‐F = 1.8705, p = 0.001) of variance in the exometabolome across the two diurnal cycles. Annotated metabolites included riboflavin, lumichrome, tryptophan, and azelaic acid, all of which have demonstrated roles in microbe–microbe interactions in other ecosystems and should be tested for potential roles in the development of microbial blooms on bare ice surfaces.

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Dark ice in a warming world: advances and challenges in the study of Greenland Ice Sheet's biological darkening

Cited by 6 publications

References 60 publications

Exploring microbial diversity in Greenland Ice Sheet supraglacial habitats through culturing-dependent and -independent approaches

Exploring microbial diversity in Greenland Ice Sheet supraglacial habitats through culturing-dependent and -independent approaches

The distinctive weathering crust habitat of a High Arctic glacier comprises discrete microbial micro‐habitats

The exometabolome of microbial communities inhabiting bare ice surfaces on the southern Greenland Ice Sheet

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