Microbial Life beneath a High Arctic Glacier

ABSTRACT The debris-rich basal ice layers of a high Arctic glacier were shown to contain metabolically diverse microbes that could be cultured oligotrophically at low temperatures (0.3 to 4°C). These organisms included aerobic chemoheterotrophs and anaerobic nitrate reducers, sulfate reducers, and methanogens. Colonies purified from subglacial samples at 4°C appeared to be predominantly psychrophilic. Aerobic chemoheterotrophs were metabolically active in unfrozen basal sediments when they were cultured at 0.3°C in the dark (to simulate nearly in situ conditions), producing 14CO2from radiolabeled sodium acetate with minimal organic amendment (≥38 μM C). In contrast, no activity was observed when samples were cultured at subfreezing temperatures (≤−1.8°C) for 66 days. Electron microscopy of thawed basal ice samples revealed various cell morphologies, including dividing cells. This suggests that the subglacial environment beneath a polythermal glacier provides a viable habitat for life and that microbes may be widespread where the basal ice is temperate and water is present at the base of the glacier and where organic carbon from glacially overridden soils is present. Our observations raise the possibility that in situ microbial production of CO2 and CH4beneath ice masses (e.g., the Northern Hemisphere ice sheets) is an important factor in carbon cycling during glacial periods. Moreover, this terrestrial environment may provide a model for viable habitats for life on Mars, since similar conditions may exist or may have existed in the basal sediments beneath the Martian north polar ice cap.

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Factors influencing the basal temperatures of a High Arctic polythermal glacier

Annals of Glaciology ◽

10.3189/172756409789624210 ◽

2009 ◽

Vol 50 (52) ◽

pp. 9-16 ◽

Cited By ~ 11

Author(s):

Trudy Wohlleben ◽

Martin Sharp ◽

Andrew Bush

Keyword(s):

Thermal Characteristics ◽

High Arctic ◽

Ice Thickness ◽

Temperature Model ◽

Canadian High Arctic ◽

Basal Ice ◽

Air Temperatures ◽

Modelling Studies ◽

Pressure Melting ◽

Polythermal Glacier

AbstractA number of glaciers in the Canadian High Arctic are composed primarily of cold ice, but the ice at or near their beds reaches the pressure-melting point (PMP) in the ablation zone. Past modelling studies have suggested that the basal temperatures of some of these glaciers reach the PMP where they should not, indicating that they are not in thermal equilibrium with present-day surface air temperatures. To investigate the possible reasons for thermal disequilibria in such glaciers, a two-dimensional ice temperature model was used to simulate the inferred thermal characteristics of John Evans Glacier, Ellesmere Island. Results indicate that while surface refreezing and historical ice-thickness changes have had a warming effect upon basal ice temperatures, supraglacial meltwater reaching the glacier bed provides the single most critical heat source for explaining the apparent thermal disequilibrium between present-day inferred ice–bed temperatures and those modelled under present-day boundary conditions.

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Phosphatase activity and organic phosphorus turnover on a high Arctic glacier

Biogeosciences Discussions ◽

10.5194/bgd-6-2697-2009 ◽

2009 ◽

Vol 6 (1) ◽

pp. 2697-2721 ◽

Cited By ~ 2

Author(s):

M. Stibal ◽

A. M. Anesio ◽

C. J. D. Blues ◽

M. Tranter

Keyword(s):

Phosphatase Activity ◽

Organic Phosphorus ◽

High Arctic ◽

Organic P ◽

Glacier Surface ◽

Nutrient Pools ◽

Inorganic P ◽

Low Concentrations ◽

Arctic Glacier

Abstract. Arctic glacier surfaces harbor abundant microbial communities consisting mainly of heterotrophic and photoautotrophic bacteria. The microbes must cope with very low concentrations of nutrients and with the fact that both the dissolved and debris-bound nutrient pools are dominated by organic phases. Here we provide evidence that phosphorus (P) is deficient and limiting in the supraglacial environment on a Svalbard glacier, we show how the microbial community responds to the P stress and we quantify the contribution of the microbes to the cycling of the dominant organic P in the supraglacial environment. Incubation of cryoconite debris revealed significant phosphatase activity in the samples (19–67 nmol MUP g−1 h−1), which was controlled by the concentration of inorganic P during incubations and had its optimum at around 30°C. The phosphatase activity rates measured at near-in situ temperature and substrate concentration imply that the available dissolved organic P can be turned over by microbes within ~3–11 h on the glacier surface. By contrast, the amount of potentially bioavailable debris-bound organic P is sufficient for a whole ablation season. However, it is apparent that some of this potentially bioavailable debris-bound P is not accessible to the microbes.

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Identification and analysis of low-molecular-weight dissolved organic carbon in subglacial basal ice ecosystems by ion chromatography

Biogeosciences ◽

10.5194/bg-13-3833-2016 ◽

2016 ◽

Vol 13 (12) ◽

pp. 3833-3846 ◽

Cited By ~ 8

Author(s):

Emily C. O'Donnell ◽

Jemma L. Wadham ◽

Grzegorz P. Lis ◽

Martyn Tranter ◽

Amy E. Pickard ◽

...

Keyword(s):

Molecular Weight ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Microbial Activity ◽

Free Amino ◽

Low Molecular Weight ◽

Subglacial Environment ◽

Basal Ice ◽

Order Of Magnitude

Abstract. Determining the concentration and composition of dissolved organic carbon (DOC) in glacial ecosystems is important for assessments of in situ microbial activity and contributions to wider biogeochemical cycles. Nonetheless, there is limited knowledge of the abundance and character of DOC in basal ice and the subglacial environment and a lack of quantitative data on low-molecular-weight (LMW) DOC components, which are believed to be highly bioavailable to microorganisms. We investigated the abundance and composition of DOC in basal ice via a molecular-level DOC analysis. Spectrofluorometry and a novel ion chromatographic method, which has been little utilized in glacial science for LMW-DOC determinations, were employed to identify and quantify the major LMW fractions (free amino acids, carbohydrates, and carboxylic acids) in basal ice from four glaciers, each with a different type of overridden material (i.e. the pre-entrainment sedimentary type such as lacustrine material or palaeosols). Basal ice from Joyce Glacier (Antarctica) was unique in that 98 % of the LMW-DOC was derived from the extremely diverse free amino acid (FAA) pool, comprising 14 FAAs. LMW-DOC concentrations in basal ice were dependent on the bioavailability of the overridden organic carbon (OC), which in turn was influenced by the type of overridden material. Mean LMW-DOC concentrations in basal ice from Russell Glacier (Greenland), Finsterwalderbreen (Svalbard), and Engabreen (Norway) were low (0–417 nM C), attributed to the relatively refractory nature of the OC in the overridden palaeosols and bedrock. In contrast, mean LMW-DOC concentrations were an order of magnitude higher (4430 nM C) in basal ice from Joyce Glacier, a reflection of the high bioavailability of the overridden lacustrine material (> 17 % of the sediment OC comprised extractable carbohydrates, a proxy for bioavailable OC). We find that the overridden material may act as a direct (via abiotic leaching) and indirect (via microbial cycling) source of DOC to the subglacial environment and provides a range of LMW-DOC compounds that may stimulate microbial activity in wet subglacial sediments.

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Enhancement of glacial solute fluxes in the proglacial zone of a polythermal glacier

Journal of Glaciology ◽

10.3189/172756501781832188 ◽

2001 ◽

Vol 47 (158) ◽

pp. 378-386 ◽

Cited By ~ 38

Author(s):

J. L Wadham ◽

R. J. Cooper ◽

M. Tranter ◽

R. Hodgkins

Keyword(s):

Active Layer ◽

Chemical Weathering ◽

High Arctic ◽

Weathering Rate ◽

Glacier Terminus ◽

Solute Fluxes ◽

Solute Acquisition ◽

Polythermal Glacier ◽

Arctic Glacier ◽

Chemical Weathering Rate

AbstractAnnual proglacial solute fluxes and chemical weathering rates at a polythermal high-Arctic glacier are presented. Bulk meltwater chemistry and discharge were monitored continuously at gauging stations located at the eastern and western margins of the glacier terminus and at “the Outlet”, 2.5 km downstream where meltwaters discharge into the fjord. Fluxes of non-snowpack HCO3−, SO42−, Ca2+ and Mg2+ increase by 30–47% between the glacier terminus and the Outlet, indicating that meltwaters are able to access and chemically weather efflorescent sulphates, carbonates and sulphides in the proglacial zone. Smaller increases in the fluxes of non-snowpack-derived Na+, K+ and Si indicate that proglacial chemical weathering of silicates is less significant. En3hanced solute fluxes in the proglacial zone are mainly due to the chemical weathering of active-layer sediments. The PCO2 of active-layer ground-waters is above atmospheric pressure. This implies that solute acquisition in the active layer involves no drawdown of CO2. The annual proglacial chemical weathering rate in 1999 is calculated to be 2600 meqΣ+ m−2. This exceeds the chemical weathering rate for the glaciated part of the catchment (790 meqΣ+ m−2) by a factor of 3.3. Hence, the proglacial zone at Finster-walderbreen is identified as an area of high geochemical reactivity and a source of CO2.

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Chemical and Isotopic Switching within the Subglacial Environment of a High Arctic Glacier

Biogeochemistry ◽

10.1007/s10533-005-3832-0 ◽

2006 ◽

Vol 78 (2) ◽

pp. 173-193 ◽

Cited By ~ 43

Author(s):

Peter M. Wynn ◽

Andrew Hodson ◽

Tim Heaton

Keyword(s):

High Arctic ◽

Subglacial Environment ◽

Arctic Glacier

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Seasonal and site-specific variations in nitrogen fixation in a high arctic area, Ny-Ålesund, Spitsbergen

Canadian Journal of Microbiology ◽

10.1139/m97-109 ◽

1997 ◽

Vol 43 (8) ◽

pp. 759-769 ◽

Cited By ~ 27

Author(s):

Turid Liengen ◽

Rolf Arnt Olsen

Keyword(s):

Nitrogen Fixation ◽

C:N Ratio ◽

High Arctic ◽

Rapid Decline ◽

Soil Cores ◽

Nostoc Commune ◽

In Situ Conditions ◽

Intact Soil Cores ◽

Intact Soil

Nitrogen fixation was measured in different habitats in the area of Ny-Ålesund, Spitsbergen, using the acetylene reduction method on intact soil cores and Nostoc commune growing in macroscopic sheet communities. The samples were incubated both under constant conditions (19 °C and 200 μE∙m−2∙s−1) and under in situ conditions. Cyanobacteria were considered to be the major nitrogen-fixing organisms. The nitrogen fixation rates showed a seasonal variation during the growing season of 1994, with low activities just after the snow melt, increasing until the middle of August and showing a rapid decline after the snow fell on August 29. The soil temperature at the time of sampling showed a positive, linear correlation with the nitrogen fixation activities measured on intact soil cores, whereas the nitrogen fixation activities measured in situ of N. commune showed a positive, linear dependence on the moisture content in the sheets and the incubation temperatures inside the incubation vessels during the experiments. The optimal temperature of the nitrogen fixation activity was about 20 °C, both for N. commune and a Puccinellia salt marsh. The highest nitrogen fixation rate measured in situ was at a patterned ground, which had the highest pH, the highest concentrations of extractable calcium and magnesium, and the highest C:N ratio measured.Key words: nitrogen fixation, cyanobacteria, Nostoc commune, high arctic.

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Basal thermal regime affects the biogeochemistry of subglacial systems

Biogeosciences ◽

10.5194/bg-17-963-2020 ◽

2020 ◽

Vol 17 (4) ◽

pp. 963-977 ◽

Cited By ~ 1

Author(s):

Ashley Dubnick ◽

Martin Sharp ◽

Brad Danielson ◽

Alireza Saidi-Mehrabad ◽

Joel Barker

Keyword(s):

Thermal Regime ◽

Major Ions ◽

Fluorescent Material ◽

Dissolved Phosphorus ◽

Subglacial Environment ◽

Basal Ice ◽

Glacier Ice ◽

Specific Fraction ◽

Ecological Importance

Abstract. Ice formed in the subglacial environment can contain some of the highest concentrations of solutes, nutrients, and microbes found in glacier systems, which can be released to downstream freshwater and marine ecosystems and glacier forefields. Despite the potential ecological importance of basal ice, our understanding of its spatial and temporal biogeochemical variability remains limited. We hypothesize that the basal thermal regime of glaciers is a dominant control on subglacial biogeochemistry because it influences the degree to which glaciers mobilize material from the underlying substrate and controls the nature and extent of biogeochemical activity that occurs at glacier beds. Here, we characterize the solutes, nutrients, and microbes found in the basal regions of a cold-based glacier and three polythermal glaciers and compare them to those found in overlying glacier ice of meteoric origin. Compared to meteoric glacier ice, basal ice from polythermal glaciers was consistently enriched in major ions, dissolved organic matter (including a specific fraction of humic-like fluorescent material), and microbes and was occasionally enriched in dissolved phosphorus and reduced nitrogen (NH4+) and in a second dissolved component of humic-like fluorescent material. In contrast, the biogeochemistry of basal ice from the cold-based glacier was remarkably similar to that of meteoric glacier ice. These findings suggest that a glacier's basal thermal regime can play an important role in determining the mix of solutes, nutrients, and microbes that are acquired from subglacial substrates or produced in situ.

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Distinct Bacterial Communities Exist beneath a High Arctic Polythermal Glacier

Applied and Environmental Microbiology ◽

10.1128/aem.00595-06 ◽

2006 ◽

Vol 72 (9) ◽

pp. 5838-5845 ◽

Cited By ~ 54

Author(s):

Maya Bhatia ◽

Martin Sharp ◽

Julia Foght

Keyword(s):

Bacterial Communities ◽

Drainage System ◽

High Arctic ◽

16S Rrna Genes ◽

Rrna Genes ◽

Polymorphism Analysis ◽

Basal Ice ◽

Seasonal Flow ◽

Glacial Environments ◽

Polythermal Glacier

ABSTRACT Bacterial communities reside in basal ice, sediment, and meltwater in the supra-, sub-, and proglacial environments of John Evans Glacier, Nunavut, Canada. We examined whether the subglacial bacterial community shares common members with the pro- and supraglacial communities, and by inference, whether it could be derived from communities in either of these environments (e.g., by ice overriding proglacial sediments or by in-wash of surface meltwaters). Terminal restriction fragment length polymorphism analysis of bacterial 16S rRNA genes amplified from these environments revealed that the subglacial water, basal ice, and sediment communities were distinct from those detected in supraglacial meltwater and proglacial sediments, with 60 of 142 unique terminal restriction fragments (T-RFs) detected exclusively in subglacial samples and only 8 T-RFs detected in all three environments. Supraglacial waters shared some T-RFs with subglacial water and ice, likely reflecting the seasonal flow of surface meltwater into the subglacial drainage system, whereas supraglacial and proglacial communities shared the fewest T-RFs. Thus, the subglacial community at John Evans Glacier appears to be predominantly autochthonous rather than allochthonous, and it may be adapted to subglacial conditions. Chemical analysis of water and melted ice also revealed differences between the supraglacial and proglacial environments, particularly regarding electrical conductivity and nitrate, sulfate, and dissolved organic carbon concentrations. Whereas the potential exists for common bacterial types to be broadly distributed throughout the glacial system, we have observed distinct bacterial communities in physically and chemically different glacial environments.

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Phosphatase activity and organic phosphorus turnover on a high Arctic glacier

Biogeosciences ◽

10.5194/bg-6-913-2009 ◽

2009 ◽

Vol 6 (5) ◽

pp. 913-922 ◽

Cited By ~ 31

Author(s):

M. Stibal ◽

A. M. Anesio ◽

C. J. D. Blues ◽

M. Tranter

Keyword(s):

Phosphatase Activity ◽

Organic Phosphorus ◽

High Arctic ◽

Organic P ◽

Glacier Surface ◽

Nutrient Pools ◽

Inorganic P ◽

Low Concentrations ◽

Arctic Glacier

Abstract. Arctic glacier surfaces harbour abundant microbial communities consisting mainly of heterotrophic and photoautotrophic bacteria. The microbes must cope with low concentrations of nutrients and with the fact that both the dissolved and debris-bound nutrient pools are dominated by organic phases. Here we provide evidence that phosphorus (P) is deficient in the supraglacial environment on a Svalbard glacier, we quantify the enzymatic activity of phosphatases in the system and we estimate the contribution of the microbes to the cycling of the dominant organic P in the supraglacial environment. Incubation of cryoconite debris revealed significant phosphatase activity in the samples (19–67 nmol MUP g−1 h−1). It was inhibited by inorganic P during incubations and had its optimum at around 30°C. The phosphatase activity measured at near-in situ temperature and substrate concentration suggests that the available dissolved organic P can be turned over by microbes within ~3–11 h on the glacier surface. By contrast, the amount of potentially bioavailable debris-bound organic P is sufficient for a whole ablation season. However, it is apparent that some of this potentially bioavailable debris-bound P is not accessible to the microbes.

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