Microbes inhabiting and evolving in aquatic ecosystems beneath polar ice sheets subsist under energy-limited conditions while in relative isolation from surface gene pools and their common ancestral populations of origin. Samples obtained from beneath West Antarctic Ice Sheet (WAIS) allowed us to examine evolutionary relationships of and identify metabolic pathways in microbial genomes recovered from the Mercer Subglacial Lake (SLM) ecosystem. We obtained 1,374 single-cell amplified genomes (SAGs) from individual bacterial and archaeal cells that were isolated from samples of SLM's water column and sediments. These genomes reveal that a diversity of microorganisms including Patescibacteria exists in SLM. Comparative analyses show that most genomes correspond to new species and taxonomic groups, with phylogenomic and functional evidence supporting their genetic isolation from marine and surface biomes. Genomic data reveal diverse metabolisms in SLM that are capable of oxidizing organic and inorganic compounds via aerobic or anaerobic respiration. Distinct metabolic guild structures are observed for the subglacial populations, where trophic shifts from organotrophy to chemolithotrophy may depend on oxygen availability. Our SAG data suggest versatile metabolic capabilities in the characterized microbial assemblage, reveal key energy-generating strategies in the subglacial aquatic ecosystem, and provide a framework to assess microbial evolution beneath WAIS.

The permanently ice‐covered lakes of Taylor Valley, Antarctica, are rare ecosystems where permanent ice cover and year‐round vertically stable water columns provide critical redox zones for cold‐adapted microorganisms. Using 30 yr of limnological data from the McMurdo Dry Valleys Long‐Term Ecological Research program, we assessed the water column heat flux of four permanently ice‐covered lakes in the context of global lake ice decline and lake warming. Our study reveals that heat flux in Taylor Valley lakes is driven by ice cover dynamics, both annual changes in ice thickness as well as overall ice thickness. During periods of ice thinning, like those observed from 2020 to 2023, the lakes accumulate heat. Lake Fryxell, Lake Hoare, and West Lake Bonney have repeatedly cooled and warmed over our record, with only East Lake Bonney cooling due to lake level rise. Ice thickness is largely synchronous among the four lakes, with periods of asynchronicity likely caused by lake‐specific changes in surface albedo driven by changes in optical properties of the ice covers and in‐ice sediment dynamics.

There is a paucity of records on decadal to millennial scales archiving the evolution of the Antarctic subglacial hydrologic system, leaving a gap in our knowledge of the links between meltwater drainage and ice behavior. We employed a suite of sedimentological and geochemical methods to assess the stratigraphic distribution of lithofacies and evaluate sedimentary processes from sediment cores collected from Mercer Subglacial Lake, located beneath the Mercer Ice Stream in West Antarctica. The composite 2.06 m sediment record consisted of massive-to-stratified diamict, massive muds, and laminated muds. Chloride concentrations indicate sediment porewater was primarily derived from glacial melt with sediment deposition in freshwater conditions. Whereas diamicts are associated with basal ice contact during ice stream grounding events (tills), sorted mud beds buried below diamict lack coarse-grained detritus (>2 mm) indicating deposition from suspension settling in slowly flowing or ponded meltwater. Rhythmically laminated sediments capping the sedimentary sequence capture modern subglacial lake conditions and are likely influenced by a continuum of processes controlled by suspended sediment delivered into the lake, water column velocity changes associated with fill-drain cycles, and sediment fallout from basal ice melt. These sedimentary facies characterize a complex subglacial hydrologic system providing evidence that basal conditions alternated from grounded ice to water-filled cavities fed and drained by subglacial meltwater. Our data provide new information on subglacial sediments beneath an Antarctic ice stream that can be used to refine our knowledge of subglacial hydrology, its coupling with ice dynamics, and as an analog for studying ancient glacial deposits.

Aquatic ecosystems - lakes, ponds and streams - are hotspots of biodiversity in the cold and arid environment of Continental Antarctica. Environmental change is expected to increasingly alter Antarctic aquatic ecosystems and modify the physical characteristics and interactions within the habitats that they support. Here, we describe physical and biological features of the peripheral 'moat' of a closed-basin Antarctic lake. These moats mediate connectivity amongst streams, lake and soils. We highlight the cyclical moat transition from a frozen winter state to an active open-water summer system, through refreeze as winter returns. Summer melting begins at the lakebed, initially creating an ice-constrained lens of liquid water in November, which swiftly progresses upwards, creating open water in December. Conversely, freezing progresses slowly from the water surface downwards, with water at 1 m bottom depth remaining liquid until May. Moats support productive, diverse benthic communities that are taxonomically distinct from those under the adjacent permanent lake ice. We show how ion ratios suggest that summer exchange occurs amongst moats, streams, soils and sub-ice lake water, perhaps facilitated by within-moat density-driven convection. Moats occupy a small but dynamic area of lake habitat, are disproportionately affected by recent lake-level rises and may thus be particularly vulnerable to hydrological change.

BACKGROUND:Lake Bonney, which is divided into a west lobe (WLB) and an east lobe (ELB), is a perennially ice-covered lake located in the McMurdo Dry Valleys of Antarctica. Despite previous reports on the microbial community dynamics of ice-covered lakes in this region, there is a paucity of information on the relationship between microbial genomic diversity and associated nutrient cycling. Here, we applied gene- and genome-centric approaches to investigate the microbial ecology and reconstruct microbial metabolic potential along the depth gradient in Lake Bonney. RESULTS:Lake Bonney is strongly chemically stratified with three distinct redox zones, yielding different microbial niches. Our genome enabled approach revealed that in the sunlit and relatively freshwater epilimnion, oxygenic photosynthetic production by the cyanobacterium Pseudanabaena and a diversity of protists and microalgae may provide new organic carbon to the environment. CO-oxidizing bacteria, such as Acidimicrobiales, Nanopelagicales, and Burkholderiaceae were also prominent in the epilimnion and their ability to oxidize carbon monoxide to carbon dioxide may serve as a supplementary energy conservation strategy. In the more saline metalimnion of ELB, an accumulation of inorganic nitrogen and phosphorus supports photosynthesis despite relatively low light levels. Conversely, in WLB the release of organic rich subglacial discharge from Taylor Glacier into WLB would be implicated in the possible high abundance of heterotrophs supported by increased potential for glycolysis, beta-oxidation, and glycoside hydrolase and may contribute to the growth of iron reducers in the dark and extremely saline hypolimnion of WLB. The suboxic and subzero temperature zones beneath the metalimnia in both lobes supported microorganisms capable of utilizing reduced nitrogens and sulfurs as electron donors. Heterotrophs, including nitrate reducing sulfur oxidizing bacteria, such as Acidimicrobiales (MAG72) and Salinisphaeraceae (MAG109), and denitrifying bacteria, such as Gracilimonas (MAG7), Acidimicrobiales (MAG72) and Salinisphaeraceae (MAG109), dominated the hypolimnion of WLB, whereas the environmental harshness of the hypolimnion of ELB was supported by the relatively low in metabolic potential, as well as the abundance of halophile Halomonas and endospore-forming Virgibacillus. CONCLUSIONS:The vertical distribution of microbially driven C, N and S cycling genes/pathways in Lake Bonney reveals the importance of geochemical gradients to microbial diversity and biogeochemical cycles with the vertical water column.

Limnology and Oceanography BulletinEarly View Viewpoint Communicating Science Through Press Releases to News Media: The Case Study of What Is Controlling the Fabled Water Clarity of Lake Tahoe Sudeep Chandra, Sudeep Chandra [email protected] orcid.org/0000-0003-1724-5154 Global Water Center, University of Nevada, Reno, NV, USASearch for more papers by this authorHans W. Paerl, Hans W. Paerl orcid.org/0000-0003-2211-1011 Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC, USASearch for more papers by this authorJohn Melack, John Melack orcid.org/0000-0003-0619-841X Bren School of Environmental Science and Management, University of California, Santa Barbara, Santa Barbara, CA, USASearch for more papers by this authorConnie Lovejoy, Connie Lovejoy orcid.org/0000-0001-8027-2281 Département de Biologie, Québec Océan, Université Laval, Québec, QC, CanadaSearch for more papers by this authorJohn C. Priscu, John C. Priscu Montana State University, Bozeman, MT, USASearch for more papers by this authorZach Bess, Zach Bess Ecology Evolution and Conservation Biology Graduate Program, University of Nevada, Reno, NV, USASearch for more papers by this authorJohn Coil, John Coil JC Oil Environmental Consulting, Davis, CA, USASearch for more papers by this authorCharles R. Goldman, Charles R. Goldman Tahoe Research Group, University of California, Davis, Emeritus Davis, CA, USASearch for more papers by this authorMichael T. Brett, Michael T. Brett orcid.org/0000-0001-5065-2144 Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USASearch for more papers by this authorErin Suenaga, Erin Suenaga Global Water Center, University of Nevada, Reno, NV, USASearch for more papers by this authorVeronica Nava, Veronica Nava orcid.org/0000-0002-2770-1937 Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milano, MI, ItalySearch for more papers by this author Sudeep Chandra, Sudeep Chandra [email protected] orcid.org/0000-0003-1724-5154 Global Water Center, University of Nevada, Reno, NV, USASearch for more papers by this authorHans W. Paerl, Hans W. Paerl orcid.org/0000-0003-2211-1011 Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC, USASearch for more papers by this authorJohn Melack, John Melack orcid.org/0000-0003-0619-841X Bren School of Environmental Science and Management, University of California, Santa Barbara, Santa Barbara, CA, USASearch for more papers by this authorConnie Lovejoy, Connie Lovejoy orcid.org/0000-0001-8027-2281 Département de Biologie, Québec Océan, Université Laval, Québec, QC, CanadaSearch for more papers by this authorJohn C. Priscu, John C. Priscu Montana State University, Bozeman, MT, USASearch for more papers by this authorZach Bess, Zach Bess Ecology Evolution and Conservation Biology Graduate Program, University of Nevada, Reno, NV, USASearch for more papers by this authorJohn Coil, John Coil JC Oil Environmental Consulting, Davis, CA, USASearch for more papers by this authorCharles R. Goldman, Charles R. Goldman Tahoe Research Group, University of California, Davis, Emeritus Davis, CA, USASearch for more papers by this authorMichael T. Brett, Michael T. Brett orcid.org/0000-0001-5065-2144 Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USASearch for more papers by this authorErin Suenaga, Erin Suenaga Global Water Center, University of Nevada, Reno, NV, USASearch for more papers by this authorVeronica Nava, Veronica Nava orcid.org/0000-0002-2770-1937 Department of Earth and Environmental Sciences, University of Milano-Bicocca, Milano, MI, ItalySearch for more papers by this author First published: 30 December 2023 https://doi.org/10.1002/lob.10624 The opinions expressed in Bulletin Viewpoints are those of the authors and contributors, and do not necessarily reflect those of ASLO, its editors or affiliates, or the organization to which the authors are affiliated. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References Autzen, C. 2014. Press releases—The new trend in science communication. J. Sci. Commun. 13: C02. doi:10.22323/2.13030302. 10.22323/2.13030302 Google Scholar Bess, Z., S. Chandra, E. Suenaga, S. Kelson, and A. Heyvaert. 2021. Zooplankton influences on phytoplankton, water clarity, and nutrients in Lake Tahoe. Aquat. Sci. 83: 26. doi:10.1007/s00027-020-00772-6. 10.1007/s00027-020-00772-6 CASWeb of Science®Google Scholar Naranjo, R. C., P. Work, A. Heyvaert, G. Schladow, A. Cortes, S. Watanabe, L. Tanaka, and S. Elci. 2022. Seasonal and long-term clarity trend assessment of Lake Tahoe, California–Nevada. USGS Numbered Series 2022–5070. 2022–5070 U.S. Geological Survey. Google Scholar U.S. Geological Survey. 2021. USGS water data for the nation. Google Scholar Watanabe, S., and G. Schladow. 2023. Lake Tahoe historic Secchi depth. doi:10.6073/PASTA/651F53D1340FC0131E05274672762F63. Google Scholar Wulfeck, A. 2023. Lake Tahoe's clarity is the best it's been in 40 years. Available from. Foxweather.com, https://www.foxweather.com/weather-news/nevada-california-quality-water-sensor. Google Scholar Early ViewOnline Version of Record before inclusion in an issue ReferencesRelatedInformation

Projections of Antarctica's contribution to future sea level rise are associated with significant uncertainty, in part because the observational record is too short to capture long‐term processes necessary to estimate ice mass changes over societally relevant timescales. Records of grounding line retreat from the geologic past offer an opportunity to extend our observations of these processes beyond the modern record and to gain a more comprehensive understanding of ice‐sheet change. Here, we present constraints on the timing and inland extent of deglacial grounding line retreat in the southern Ross Sea, Antarctica, obtained via direct sampling of a subglacial lake located 150 km inland from the modern grounding line and beneath >1 km of ice. Isotopic measurements of water and sediment from the lake enabled us to evaluate how the subglacial microbial community accessed radiocarbon‐bearing organic carbon for energy, as well as where it transferred carbon metabolically. Using radiocarbon as a natural tracer, we found that sedimentary organic carbon was microbially translocated to dissolved carbon pools in the subglacial hydrologic system during the 4.5‐year period of water accumulation prior to our sampling. This finding indicates that the grounding line along the Siple Coast of West Antarctica retreated more than 250 km inland during the mid‐Holocene (6.3 ± 1.0 ka), prior to re‐advancing to its modern position.

Ammonia-oxidizing archaea (AOA) play a key role in the aquatic nitrogen cycle. Their genetic diversity is viewed as the outcome of evolutionary processes that shaped ancestral transition from terrestrial to marine habitats. However, current genome-wide insights into AOA evolution rarely consider brackish and freshwater representatives or provide their divergence timeline in lacustrine systems. An unbiased global assessment of lacustrine AOA diversity is critical for understanding their origins, dispersal mechanisms, and ecosystem roles. Here, we leveraged continental-scale metagenomics to document that AOA species diversity in freshwater systems is remarkably low compared to marine environments. We show that the uncultured freshwater AOA, “ Candidatus Nitrosopumilus limneticus,” is ubiquitous and genotypically static in various large European lakes where it evolved 13 million years ago. We find that extensive proteome remodeling was a key innovation for freshwater colonization of AOA. These findings reveal the genetic diversity and adaptive mechanisms of a keystone species that has survived clonally in lakes for millennia.

Over the past 50 years, the discovery and initial investigation of subglacial lakes in Antarctica have highlighted the paleoglaciological information that may be recorded in sediments at their beds. In December 2018, we accessed Mercer Subglacial Lake, West Antarctica, and recovered the first in situ subglacial lake-sediment record—120 mm of finely laminated mud. We combined geophysical observations, image analysis, and quantitative stratigraphy techniques to estimate long-term mean lake sedimentation rates (SRs) between 0.49 ± 0.12 mm a–1 and 2.3 ± 0.2 mm a–1, with a most likely SR of 0.68 ± 0.08 mm a–1. These estimates suggest that this lake formed between 53 and 260 a before core recovery (BCR), with a most likely age of 180 ± 20 a BCR—coincident with the stagnation of the nearby Kamb Ice Stream. Our work demonstrates that interconnected subglacial lake systems are fundamentally linked to larger-scale ice dynamics and highlights that subglacial sediment archives contain powerful, century-scale records of ice history and provide a modern process-based analogue for interpreting paleo–subglacial lake facies.

Whillans Subglacial Lake (SLW) lies beneath 801 m of ice in the lower portion of the Whillans Ice Stream (WIS) in West Antarctica and is part of an extensive and active subglacial drainage network. Here, the geochemical characterization of SLW rare earth elements (REE), trace elements (TE), free amino acids (FAA), and phenolic compounds (PC) measured in lakewater and sediment porewater are reported. The results show, on average, higher values of REEs in the lakewater than in the porewater, and clear changes in all REE concentrations and select redox sensitive trace element concentrations in porewaters at a depth of similar to 15 cm in the 38 cm lake sediment core. This is consistent with prior results on the lake sediment redox conditions based on gas chemistry and microbiological data. Low concentrations of vanillyl phenols were measured in the SLW water column with higher concentrations in porewater samples and their concentration profiles in the sediments may also reflect changing redox conditions in the sediments. Vanillin concentrations increased with depth in the sediments as oxygenation decreases, while the concentrations of vanillic acid, the more oxidized component, were higher in the more oxygenated surface sediments. Collectively these results indicate redox changes occurring with the upper 38 cm of sediment in SLW and provide support for the existence of a seawater source, already hypothesized, in the sediments below the lowest measured depth, and of a complex and dynamic geochemical system beneath the West Antarctic Ice Sheet. Our results are the first to detail geochemical properties from an Antarctic subglacial environment using direct sampling technology. Due to their isolation from the wider environment, subglacial lakes represent one of our planets last pristine environments that provide habitats for microbial life and natural biogeochemical cycles but also impact the basal hydrology and can cause ice flow variations.

Oxygen consumption in aquatic sediments is an indicator of overall biological activity of the ecosystem. As such, rates of sedimentary oxygen utilization are well documented for much of the open oceans and freshwater lakes. However, there are few direct measurements of sedimentary oxygen consumption from Antarctic subglacial aquatic sediments. We report the first microsensor oxygen profiles and derived sedimentary oxygen consumption rates from beneath the Ross Ice Shelf and a subglacial lake beneath the West Antarctic Ice Sheet. Rates of oxygen consumption in these two environments are relatively low, but comparable to those reported from ice-free polar oceans and oligotrophic Arctic lakes. Our study demonstrates the presence of oxygen within Antarctic subglacial aquatic sediments and its importance for oxygen-consuming microorganisms living in these ecosystems.

During the 2018-2019 Antarctic field season, the Subglacial Antarctic Lakes Scientific Access project team cleanly accessed Mercer Subglacial Lake, West Antarctica, to sample water and sediments beneath 1087 m of overlying ice. A multicorer was successful in sampling the sediment-water interface, with 4 deployments retrieving 10 cores between 0.3 and 0.4 m in length. Gravity coring was also successful, retrieving cores of 0.97 and 1.78 m in glacial diamict. However, sediment cores retrieved by the gravity cores were shorter than the core barrel penetration (as measured by mud streaks on the outside of the coring system), indicating that the system can likely be improved. This manuscript describes the design, implementation, successes, and lessons learned while coring sediments in a subglacial lake.

Ice streams that flow into Ross Ice Shelf are underlain by water-saturated sediments, a dynamic hydrological system, and subglacial lakes that intermittently discharge water downstream across grounding zones of West Antarctic Ice Sheet (WAIS). A 2.06 m composite sediment profile was recently recovered from Mercer Subglacial Lake, a 15 m deep water cavity beneath a 1087 m thick portion of the Mercer Ice Stream. We examined microbial abundances, used 16S rRNA gene amplicon sequencing to assess community structures, and characterized extracellular polymeric substances (EPS) associated with distinct lithologic units in the sediments. Bacterial and archaeal communities in the surficial sediments are more abundant and diverse, with significantly different compositions from those found deeper in the sediment column. The most abundant taxa are related to chemolithoautotrophs capable of oxidizing reduced nitrogen, sulfur, and iron compounds with oxygen, nitrate, or iron. Concentrations of dissolved methane and total organic carbon together with water content in the sediments are the strongest predictors of taxon and community composition. δ¹³C values for EPS (−25 to −30‰) are consistent with the primary source of carbon for biosynthesis originating from legacy marine organic matter. Comparison of communities to those in lake sediments under an adjacent ice stream (Whillans Subglacial Lake) and near its grounding zone provide seminal evidence for a subglacial metacommunity that is biogeochemically and evolutionarily linked through ice sheet dynamics and the transport of microbes, water, and sediments beneath WAIS.

Glaciers can accumulate and release organic matter affecting the structure and function of associated terrestrial and aquatic ecosystems. We analyzed 18 ice cores collected from six locations in Taylor Valley (McMurdo Dry Valleys), Antarctica to determine the spatial abundance and quality of organic matter, and the spatial distribution of bacterial density and community structure from the terminus of the Taylor Glacier to the coast (McMurdo Sound). Our results showed that dissolved and particulate organic carbon (DOC and POC) concentrations in the ice core samples increased from the Taylor Glacier to McMurdo Sound, a pattern also shown by bacterial cell density. Fluorescence Excitation Emission Matrices Spectroscopy (EEMs) and multivariate parallel factor (PARAFAC) modeling identified one humic-like (C1) and one protein-like (C2) component in ice cores whose fluorescent intensities all increased from the Polar Plateau to the coast. The fluorescence index showed that the bioavailability of dissolved organic matter (DOM) also decreased from the Polar Plateau to the coast. Partial least squares path modeling analysis revealed that bacterial abundance was the main positive biotic factor influencing both the quantity and quality of organic matter. Marine aerosol influenced the spatial distribution of DOC more than katabatic winds in the ice cores. Certain bacterial taxa showed significant correlations with DOC and POC concentrations. Collectively, our results show the tight connectivity among organic matter spatial distribution, bacterial abundance and meteorology in the McMurdo Dry Valley ecosystem.

AbstractThe McMurdo Dry Valleys (MDVs), Antarctica, represent a cold, desert ecosystem poised on the threshold of melting and freezing water. The MDVs have experienced dramatic signs of climatic change, most notably a warm austral summer in 2001–2002 that caused widespread flooding, partial ice cover loss and lake level rise. To understand the impact of these climatic disturbances on lake microbial communities, we simulated lake level rise and ice‐cover loss by transplanting dialysis‐bagged communities from selected depths to other locations in the water column or to an open water perimeter moat. Bacteria and eukaryote communities residing in the surface waters (5 m) exhibited shifts in community composition when exposed to either disturbance, while microbial communities from below the surface were largely unaffected by the transplant. We also observed an accumulation of labile dissolved organic carbon in the transplanted surface communities. In addition, there were taxa‐specific sensitivities: cryptophytes and Actinobacteria were highly sensitive particularly to the moat transplant, while chlorophytes and several bacterial taxa increased in relative abundance or were unaffected. Our results reveal that future climate‐driven disturbances will likely undermine the stability and productivity of MDV lake phytoplankton and bacterial communities in the surface waters of this extreme environment.

Abstract Water movement in ice‐covered lakes is known to be driven by wind, sediment heat flux, solar radiation, saline density flows, and advective stream discharge. In large ice‐covered lakes, wind‐induced oscillations have been found to play a major role in horizontal flows. Here, we report recurrent, wind‐driven, barotropic seiches in a small lake with a thick (~4 m) permanent ice‐cover. Between 2010 and 2016, we recorded 10.5‐ to 13‐min oscillations of the hydrostatic water level in Lake Hoare, McMurdo Dry Valleys, East Antarctica, using pressure transducers moored to the lake bottom and suspended from the ice cover. Theoretical calculations showed a barotropic seiche should have a period of 12.6 min. Barotropic seiches were most frequent during high wind events (> 5 m s−1) in winter months (February–November). The period increased during summer months (December–January) when fast ice thinned and melted along the shoreline.

AbstractThe Subglacial Antarctic Lakes Scientific Access (SALSA) Project accessed Mercer Subglacial Lake using environmentally clean hot-water drilling to examine interactions among ice, water, sediment, rock, microbes and carbon reservoirs within the lake water column and underlying sediments. A ~0.4 m diameter borehole was melted through 1087 m of ice and maintained over ~10 days, allowing observation of ice properties and collection of water and sediment with various tools. Over this period, SALSA collected: 60 L of lake water and 10 L of deep borehole water; microbes >0.2 μm in diameter from in situ filtration of ~100 L of lake water; 10 multicores 0.32–0.49 m long; 1.0 and 1.76 m long gravity cores; three conductivity–temperature–depth profiles of borehole and lake water; five discrete depth current meter measurements in the lake and images of ice, the lake water–ice interface and lake sediments. Temperature and conductivity data showed the hydrodynamic character of water mixing between the borehole and lake after entry. Models simulating melting of the ~6 m thick basal accreted ice layer imply that debris fall-out through the ~15 m water column to the lake sediments from borehole melting had little effect on the stratigraphy of surficial sediment cores.

Aquatic subglacial habitats occur throughout the cryosphere where basal melting is sufficient to produce aqueous environments (Priscu & Christner, 2004). Heat energy for melting of basal ice is produced by frictional heating due to glacier movement and geothermal heat flux (Fisher et al., 2015). These heat sources in concert with the lowering of the pressure melting point due to the weight and insulating properties of the overlying ice all contribute to basal ice melting.

Subglacial Lake Whillans lies below around 800 m of Antarctic ice and is isolated from fresh sources of photosynthetic organic matter to sustain life. The diverse microbial ecosystems within the lake and underlying sediments are therefore dependent on a combination of relict, overridden, marine-derived organic matter and mineral-derived energy. Here, we conduct experiments to replicate subglacial erosion involving both gentle and high-energy crushing of Subglacial Lake Whillans sediments and the subsequent addition of anoxic water. We find that substantial quantities of reduced species, including hydrogen, methane, acetate and ammonium and oxidised species such as hydrogen peroxide, sulfate and carbon dioxide are released. We propose that the concomitant presence of both hydrogen and hydrogen peroxide, alongside high concentrations of mineral surface radicals, suggests that the splitting of water on freshly abraded mineral surfaces increases the concentrations of redox pairs from rock-water reactions and could provide a mechanism to augment the energy available to microbial ecosystems.