02367nas a2200289 4500008004100000245011400041210006900155260001200224300001400236490000600250520147700256653001501733653002201748653002201770653001001792100002601802700002401828700002701852700002101879700001801900700001701918700002001935700001701955700001701972700002401989856006402013 2022 eng d00aElevational constraints on the composition and genomic attributes of microbial communities in Antarctic soils0 aElevational constraints on the composition and genomic attribute c01/2022 ae01330-210 v73 a

The inland soils found on the Antarctic continent represent one of the more challenging environments for microbial life on Earth. Nevertheless, Antarctic soils harbor unique bacterial and archaeal (prokaryotic) communities able to cope with extremely cold and dry conditions. These communities are not homogeneous, and the taxonomic composition and functional capabilities (genomic attributes) of these communities across environmental gradients remain largely undetermined. We analyzed the prokaryotic communities in soil samples collected from across the Shackleton Glacier region of Antarctica by coupling quantitative PCR, marker gene amplicon sequencing, and shotgun metagenomic sequencing. We found that elevation was the dominant factor explaining differences in the structures of the soil prokaryotic communities, with the drier and saltier soils found at higher elevations harboring less diverse communities and unique assemblages of cooccurring taxa. The higher-elevation soil communities also had lower maximum potential growth rates (as inferred from metagenome-based estimates of codon usage bias) and an overrepresentation of genes associated with trace gas metabolism. Together, these results highlight the utility of assessing community shifts across pronounced environmental gradients to improve our understanding of the microbial diversity found in Antarctic soils and the strategies used by soil microbes to persist at the limits of habitability.

10aAntarctica10amicrobial ecology10asoil microbiology10asoils1 aDragone, Nicholas, B.1 aHenley, Jessica, B.1 aHolland-Moritz, Hannah1 aDiaz, Melisa, A.1 aHogg, Ian, D.1 aLyons, Berry1 aWall, Diana, H.1 aAdams, Byron1 aFierer, Noah1 aMackelprang, Rachel uhttps://journals.asm.org/doi/full/10.1128/msystems.01330-2102506nas a2200289 4500008004100000022001400041245006300055210006300118260001200181490000800193520169900201653001501900653001701915653001301932653001801945653001001963653001001973100002601983700002102009700001802030700001702048700002002065700002002085700002102105700001702126856007302143 2021 eng d a2169-895300aExploring the boundaries of microbial habitability in soil0 aExploring the boundaries of microbial habitability in soil c06/20210 v1263 a

Microbes are widely assumed to be capable of colonizing even the most challenging terrestrial surface environments on Earth given enough time. We would not expect to find surface soils uninhabited by microbes as soils typically harbor diverse microbial communities and viable microbes have been detected in soils exposed to even the most inhospitable conditions. However, if uninhabited soils do exist, we might expect to find them in Antarctica. We analyzed 204 ice-free soils collected from across a remote valley in the Transantarctic Mountains (84–85°S, 174–177°W) and were able to identify a potential limit of microbial habitability. While most of the soils we tested contained diverse microbial communities, with fungi being particularly ubiquitous, microbes could not be detected in many of the driest, higher elevation soils—results that were confirmed using cultivation-dependent, cultivation-independent, and metabolic assays. While we cannot confirm that this subset of soils is completely sterile and devoid of microbial life, our results suggest that microbial life is severely restricted in the coldest, driest, and saltiest Antarctic soils. Constant exposure to these conditions for thousands of years has limited microbial communities so that their presence and activity is below detectable limits using a variety of standard methods. Such soils are unlikely to be unique to the studied region with this work supporting previous hypotheses that microbial habitability is constrained by near-continuous exposure to cold, dry, and salty conditions, establishing the environmental conditions that limit microbial life in terrestrial surface soils.

10aAntarctica10aastrobiology10abacteria10aextremophiles10afungi10asoils1 aDragone, Nicholas, B.1 aDiaz, Melisa, A.1 aHogg, Ian, D.1 aLyons, Berry1 aJackson, Andrew1 aWall, Diana, H.1 aAdams, Byron, J.1 aFierer, Noah uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG00605200939nas a2200217 4500008004100000022001400041245011900055210006900174260001200243100001600255700002000271700002200291700002100313700002500334700002000359700002400379700001700403700002200420700002400442856025500466 2016 eng d a0722-406000aEvidence for dispersal and habitat controls on pond diatom communities from the McMurdo Sound Region of Antarctica0 aEvidence for dispersal and habitat controls on pond diatom commu c02/20161 aSakaeva, A.1 aSokol, Eric, R.1 aKohler, Tyler, J.1 aStanish, Lee, F.1 aSpaulding, Sarah, A.1 aHowkins, Adrian1 aWelch, Kathleen, A.1 aLyons, Berry1 aBarrett, John, E.1 aMcKnight, Diane, M. uhttp://link.springer.com/10.1007/s00300-016-1901-6http://link.springer.com/content/pdf/10.1007/s00300-016-1901-6http://link.springer.com/content/pdf/10.1007/s00300-016-1901-6.pdfhttp://link.springer.com/article/10.1007/s00300-016-1901-6/fulltext.html01522nas a2200181 4500008004100000022001400041245007100055210006900126260001200195300001400207490000700221520096100228100002101189700002401210700001701234700002401251856006501275 2015 eng d a0954-102000aExperimental formation of pore fluids in McMurdo Dry Valleys soils0 aExperimental formation of pore fluids in McMurdo Dry Valleys soi c04/2015 a163 - 1710 v273 a

The aim of the study was to determine if soil salt deliquescence and brine hydration can occur under laboratory conditions using natural McMurdo Dry Valleys soils. The experiment was a laboratory analogue for the formation of isolated patches of hypersaline, damp soil, referred to as ‘wet patches’. Soils were oven dried and then hydrated in one of two humidity chambers: one at 100% relative humidity and the second at 75% relative humidity. Soil hydration is highly variable, and over the course of 20 days of hydration, ranged from increases in water content by mass from 0–16% for 122 soil samples from Taylor Valley. The rate and absolute amount of soil hydration correlates well with the soluble salt content of the soils but not with grain size distribution. This suggests that the formation of bulk pore waters in these soils is a consequence of salt deliquescence and hydration of the brine from atmospheric water vapour.

1 aLevy, Joseph, S.1 aFountain, Andrew, G1 aLyons, Berry1 aWelch, Kathleen, A. uhttp://www.journals.cambridge.org/abstract_S095410201400047902515nas a2200169 4500008004100000022001400041245016900055210006900224260001600293300001400309490000700323520188900330100002102219700002302240700001702263856006502280 2014 eng d a0954-102000aThe effects of high meltwater on the limnology of Lake Fryxell and Lake Hoare, Taylor Valley, Antarctica, as shown by dissolved gas, tritium and chlorofluorocarbons0 aeffects of high meltwater on the limnology of Lake Fryxell and L cJan-08-2014 a331 - 3400 v263 a

Small changes in the availability of liquid water can have profound effects on the water levels, aqueous chemistry and biogeochemical dynamics of the closed-basin, perennially ice-covered lakes of the McMurdo Dry Valleys, Antarctica. We have compiled the published and unpublished data on dissolved gas, tritium and chlorofluorocarbons (CFCs) for Lake Fryxell and Lake Hoare to determine the effects of a high meltwater year (2001–02 summer) on the lakes. The dissolved gas, tritium and CFC data indicate that the pulse of freshwater that flowed onto the surfaces of the lakes did not mix extensively with the upper water column. At the bottom of Lake Hoare, the measurable CFC and lower dissolved gas values suggest that the recent meltwater may have mixed with bottom waters. The probable mechanism for this transportation is weak density currents with c. 0.1–1.5% surface water being transported downwards in Lake Hoare. This deep water input, while not constant, may have a significant effect on the chemistry of the bottom waters in Lake Hoare over time. In Lake Fryxell, the tritium and CFC data indicate that the recent meltwater did not significantly affect the bottom water chemistry; therefore, weak density currents may not be present in Lake Fryxell.

1 aDowling, Carolyn1 aPoreda, Robert, J.1 aLyons, Berry uhttp://www.journals.cambridge.org/abstract_S095410201300062X03450nas a2200169 4500008004100000245009600041210006900137260004500206300000800251490001800259520283100277100003003108700001703138700002003155700001803175856008703193 2014 eng d00aElemental Cycling in a Flow-Through Lake in the McMurdo Dry Valleys, Antarctica: Lake Miers0 aElemental Cycling in a FlowThrough Lake in the McMurdo Dry Valle aColumbusbOhio State Universityc06/2014 a1220 vMaster Thesis3 a

The ice-free area in Antarctica known as the McMurdo Dry Valleys has been monitored biologically, meteorologically, hydrologically, and geochemically continuously since the onset of the MCM-LTER in 1993. This area contains a functioning ecosystem living in an extremely delicate environment. Only a few degrees of difference in air temperature can effect on the hydrologic system, making it a prime area to study ongoing climate change. The unique hydrology of Lake Miers, i.e. its flowthrough nature, makes it an ideal candidate to study the mass balance of a McMurdo Dry Valley lake because both input and output concentrations can be analyzed. This study seeks to understand the physical and geochemical hydrology of Lake Miers relative to other MCMDV lakes. Samples were collected from the two inflowing streams, the outflowing stream, and the lake itself at 11 depths to analyze a suite of major cations (Li+ , Na+ , K+ , Mg+ , Ca2+), major anions (Cl- , Br- , F- , SO4 2- , ΣCO2), nutrients (NO2 - , NO3 - , NH4 + , PO4 3- , Si), trace elements (Mo, Rb, Sr, Ba, U, V, Cu, As), water isotopes (δD, δ 18O), and dissolved organic carbon (DOC). The lake acts as a sink for all constituents analyzed, but by amounts varying from ~10% (DOC, NH4 + , and NO2 - ) to PO4 3- at nearly 100%, indicating this lake may be P-limited. Cl- , a typically conservative element, was only 79% retained, which could be due to the late season sample collection, hyperheic zone influences, or other factors. The hyperheic zone’s role in lake and stream iii geochemistry was analyzed with a 24-hour sampling event. The positive relationships between stream flow and solute concentrations indicate that the delta in Miers Valley plays a role in controlling stream geochemistry and future work could help to explain this relationship. Lake depth profiles of trace elements U, V, Cu, and As decrease relative to Cl in the deepest part of the lake, while non-reducing trace elements show increases with depth. SO4 2- and dissolved O2 lake depth profiles decrease from 53 μM and 22.3 mg/L to 18 μM and 1.8 mg/L, respectively, at depth, indicating that the lake bottom is under reducing and near anoxic conditions. Lake depth profiles show that, while the “biological pump” may be a factor controlling lake chemistry, it is masked by the stronger signal of diffusion from the lake bottom sediments and requires future work to understand fully. The “age” of Lake Miers was calculated with a diffusion model to be 84 years, which agrees with other estimates of 100-300 years. The diffusion of solutes from the lake bottom and the redox conditions at depth are two major processes controlling the geochemistry of Lake Miers, and future work can help determine their extent and relationship with other processes.

1 aFair, Alexandria, Corinne1 aLyons, Berry1 aCarey, Anne, E.1 aChin, Yu-Ping uhttps://etd.ohiolink.edu/!etd.send_file?accession=osu1413291502&disposition=inline00667nas a2200181 4500008004100000245009000041210006900131300001200200490000700212100002000219700002400239700002700263700001700290700002100307700001500328700002400343856011800367 2004 eng d00aExtreme hydrochemical conditions in natural microcosms entombed within Antarctic ice.0 aExtreme hydrochemical conditions in natural microcosms entombed  a379-3870 v181 aTranter, Martyn1 aFountain, Andrew, G1 aFritsen, Christian, H.1 aLyons, Berry1 aPriscu, John, C.1 aStathan, P1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/extreme-hydrochemical-conditions-natural-microcosms-entombed-within-antarctic-ice00605nas a2200169 4500008004100000245008000041210006900121300001200190490000700202100002100209700002000230700001900250700002200269700002100291700001700312856010600329 1998 eng d00aEvidence of deep circulation in two perennially ice-covered Antarctic lakes0 aEvidence of deep circulation in two perennially icecovered Antar a625-6350 v431 aTyler, Scott, W.1 aCook, Peter, G.1 aButt, Anya, Z.1 aThomas, James, M.1 aDoran, Peter, T.1 aLyons, Berry uhttps://mcm.lternet.edu/content/evidence-deep-circulation-two-perennially-ice-covered-antarctic-lakes