02145nas a2200409 4500008004100000245007300041210006900114260001200183490000700195520089800202653005701100653003001157653002601187653001701213653002401230653002001254653001001274100002001284700002101304700001701325700002201342700001801364700002101382700001601403700002101419700001501440700001801455700002301473700001801496700002601514700002201540700002301562700002201585700002501607700001901632856008401651 2024 eng d00aBiogeographic survey of soil bacterial communities across Antarctica0 aBiogeographic survey of soil bacterial communities across Antarc c01/20240 v123 a

Antarctica and its unique biodiversity are increasingly at risk from the effects of global climate change and other human influences. A significant recent element underpinning strategies for Antarctic conservation has been the development of a system of Antarctic Conservation Biogeographic Regions (ACBRs). The datasets supporting this classification are, however, dominated by eukaryotic taxa, with contributions from the bacterial domain restricted to Actinomycetota and Cyanobacteriota. Nevertheless, the ice-free areas of the Antarctic continent and the sub-Antarctic islands are dominated in terms of diversity by bacteria. Our study aims to generate a comprehensive phylogenetic dataset of Antarctic bacteria with wide geographical coverage on the continent and sub-Antarctic islands, to investigate whether bacterial diversity and distribution is reflected in the current ACBRs.

10aAntarctic Conservation Biogeographic Regions (ACBRs)10aAntarctic soil microbiome10abioclimatic variables10abiogeography10amicrobial diversity10aregionalization10asoils1 aVarliero, Gilda1 aLebre, Pedro, H.1 aAdams, Byron1 aChown, Steven, L.1 aConvey, Peter1 aDennis, Paul, G.1 aFan, Dandan1 aFerrari, Belinda1 aFrey, Beat1 aHogg, Ian, D.1 aHopkins, David, W.1 aKong, Weidong1 aMakhalanyane, Thulani1 aMatcher, Gwynneth1 aNewsham, Kevin, K.1 aStevens, Mark, I.1 aWeigh, Katherine, V.1 aCowan, Don, A. uhttps://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-023-01719-302587nas a2200313 4500008004100000022001400041245012700055210006900182260001200251300001100263520145800274653001701732653001401749653000801763653001901771653001501790100002301805700001801828700001501846700002401861700002501885700003301910700002901943700001701972700002201989700002102011700002102032856022002053 2024 eng d a0954-102000aMcMurdo Dry Valley lake edge ‘moats’: The ecological intersection between terrestrial and aquatic polar desert habitat0 aMcMurdo Dry Valley lake edge moats The ecological intersection b c04/2024 a1 - 173 a

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.

10aconnectivity10aecosystem10aice10amicrobial mats10atransition1 aStone, Michael, S.1 aDevlin, Shawn1 aHawes, Ian1 aWelch, Kathleen, A.1 aGooseff, Michael, N.1 aTakacs-Vesbach, Cristina, D.1 aMorgan-Kiss, Rachael, M.1 aAdams, Byron1 aBarrett, John, E.1 aPriscu, John, C.1 aDoran, Peter, T. uhttps://www.cambridge.org/core/journals/antarctic-science/article/mcmurdo-dry-valley-lake-edge-moats-the-ecological-intersection-between-terrestrial-and-aquatic-polar-desert-habitats/31D94DD51E651603482A3AE6E8A52A5702499nas a2200277 4500008004100000245009500041210006900136260001200205300000800217490000700225520169100232653001001923653002701933653001801960653002501978653001502003100002302018700002202041700001802063700002202081700001902103700001702122700002002139700001802159856004402177 2023 eng d00aBiogeography and genetic diversity of terrestrial mites in the Ross Sea region, Antarctica0 aBiogeography and genetic diversity of terrestrial mites in the R c03/2023 a6060 v143 a

Free-living terrestrial mites (Acari) have persisted through numerous glacial cycles in Antarctica. Very little is known, however, of their genetic diversity and distribution, particularly within the Ross Sea region. To redress this gap, we sampled mites throughout the Ross Sea region, East Antarctica, including Victoria Land and the Queen Maud Mountains (QMM), covering a latitudinal range of 72–85 °S, as well as Lauft Island near Mt. Siple (73 °S) in West Antarctica and Macquarie Island (54 °S) in the sub-Antarctic. We assessed genetic diversity using mitochondrial cytochrome c oxidase subunit I gene sequences (COI-5P DNA barcode region), and also morphologically identified voucher specimens. We obtained 130 sequences representing four genera: Nanorchestes (n = 30 sequences), Stereotydeus (n = 46), Coccorhagidia (n = 18) and Eupodes (n = 36). Tree-based analyses (maximum likelihood) revealed 13 genetic clusters, representing as many as 23 putative species indicated by barcode index numbers (BINs) from the Barcode of Life Datasystems (BOLD) database. We found evidence for geographically-isolated cryptic species, e.g., within Stereotydeus belli and S. punctatus, as well as unique genetic groups occurring in sympatry (e.g., Nanorchestes spp. in QMM). Collectively, these data confirm high genetic divergence as a consequence of geographic isolation over evolutionary timescales. From a conservation perspective, additional targeted sampling of understudied areas in the Ross Sea region should be prioritised, as further diversity is likely to be found in these short-range endemic mites.

10aAcari10aAntarctic conservation10aDNA barcoding10ageographic isolation10aspeciation1 aCollins, Gemma, E.1 aYoung, Monica, R.1 aConvey, Peter1 aChown, Steven, L.1 aCary, Craig, S1 aAdams, Byron1 aWall, Diana, H.1 aHogg, Ian, D. uhttps://www.mdpi.com/2073-4425/14/3/60602076nas a2200313 4500008004100000245008700041210006900128260001200197300001100209490000800220520114900228653002801377653002701405653002401432653002401456653001301480653000901493100001301502700002501515700001601540700002201556700001701578700001801595700001601613700002401629700002001653700001701673856007201690 2023 eng d00aEcological stoichiometry drives the evolution of soil nematode life history traits0 aEcological stoichiometry drives the evolution of soil nematode l c02/2023 a1088910 v1773 a

Ecological stoichiometry is a useful theoretical framework for understanding the sources and controls on nutrient availability that structure the composition and diversity of biotic communities. One such relationship is that organismal development rate is positively linked to cellular Phosphorus (P). We hypothesized that P availability, relative to other nutrients, e.g., nitrogen and carbon, would drive the evolution of traits associated with organismal growth and development. We examined the effects of P availability both in situ and in vitro, on free-living soil nematodes. We found that P-deficient environments produce predictable changes in the ecology and evolution of important life history traits. Our results identify altered rRNA gene copy number and subsequent changes in gene expression and protein synthesis as mechanisms by which P-deficiency influences these traits. These findings have important implications for explaining soil ecological and evolutionary patterns across multiple levels of organization, including the structure and functioning of organisms, populations, communities, and ecosystems.

10aelemental stoichiometry10agrowth rate hypothesis10alife history theory10amolecular evolution10anematoda10arRNA1 aXue, Xia1 aAdhikari, Bishwo, N.1 aBall, Becky1 aBarrett, John, E.1 aMiao, Jinxin1 aPerkes, Ammon1 aMartin, Mac1 aSimmons, Breana, L.1 aWall, Diana, H.1 aAdams, Byron uhttps://www.sciencedirect.com/science/article/pii/S003807172200348002098nas a2200265 4500008004100000022001400041245010400055210006900159260001200228300001200240490000800252520131200260653001601572653001501588653001801603653002501621653002101646653001301667653002201680100001601702700001401718700001401732700002901746856005701775 2023 eng d a0166-859500aHigh salt-induced PSI-supercomplex is associated with high CEF and attenuation of state transitions0 aHigh saltinduced PSIsupercomplex is associated with high CEF and c09/2023 a65 - 840 v1573 a

While PSI-driven cyclic electron flow (CEF) and assembly of thylakoid supercomplexes have been described in model organisms like Chlamydomonas reinhardtii, open questions remain regarding their contributions to survival under long-term stress. The Antarctic halophyte, C. priscuii UWO241 (UWO241), possesses constitutive high CEF rates and a stable PSI-supercomplex as a consequence of adaptation to permanent low temperatures and high salinity. To understand whether CEF represents a broader acclimation strategy to short- and long-term stress, we compared high salt acclimation between the halotolerant UWO241, the salt-sensitive model, C. reinhardtii, and a moderately halotolerant Antarctic green alga, C. sp. ICE-MDV (ICE-MDV). CEF was activated under high salt and associated with increased non-photochemical quenching in all three Chlamydomonas species. Furthermore, high salt-acclimated cells of either strain formed a PSI-supercomplex, while state transition capacity was attenuated. How the CEF-associated PSI-supercomplex interferes with state transition response is not yet known. We present a model for interaction between PSI-supercomplex formation, state transitions, and the important role of CEF for survival during long-term exposure to high salt.

10aacclimation10aAntarctica10aChlamydomonas10aCyclic electron flow10aPSI-supercomplex10asalinity10astate transitions1 aKalra, Isha1 aWang, Xin1 aZhang, Ru1 aMorgan-Kiss, Rachael, M. uhttps://link.springer.com/10.1007/s11120-023-01032-y02814nas a2200373 4500008004100000022001400041245010900055210006900164260001200233520170200245653002001947653001001967653001101977653001201988653001102000653001102011100002502022700001902047700001902066700001702085700002102102700002302123700002402146700002502170700002402195700002602219700002102245700002202266700002202288700002102310700001802331700002202349856006902371 2023 eng d a0886-623600aLong-term changes in concentration and yield of riverine dissolved silicon from the poles to the tropics0 aLongterm changes in concentration and yield of riverine dissolve c08/20233 a

Riverine exports of silicon (Si) influence global carbon cycling through the growth of marine diatoms, which account for ∼25% of global primary production. Climate change will likely alter river Si exports in biome-specific ways due to interacting shifts in chemical weathering rates, hydrologic connectivity, and metabolic processes in aquatic and terrestrial systems. Nonetheless, factors driving long-term changes in Si exports remain unexplored at local, regional, and global scales. We evaluated how concentrations and yields of dissolved Si (DSi) changed over the last several decades of rapid climate warming using long-term datasets from 60 rivers and streams spanning the globe (e.g., Antarctic, tropical, temperate, boreal, alpine, Arctic systems). We show that widespread changes in river DSi concentration and yield have occurred, with the most substantial shifts occurring in alpine and polar regions. The magnitude and direction of trends varied within and among biomes, were most strongly associated with differences in land cover, and were often independent of changes in river discharge. These findings indicate that there are likely diverse mechanisms driving change in river Si biogeochemistry that span the land-water interface, which may include glacial melt, changes in terrestrial vegetation, and river productivity. Finally, trends were often stronger in months outside of the growing season, particularly in temperate and boreal systems, demonstrating a potentially important role of shifting seasonality for the flux of Si from rivers. Our results have implications for the timing and magnitude of silica processing in rivers and its delivery to global oceans.

10abiogeochemistry10ariver10asilica10asilicon10astream10atrends1 aJankowski, Kathi, Jo1 aJohnson, Keira1 aSethna, Lienne1 aJulian, Paul1 aWymore, Adam, S.1 aShogren, Arial, J.1 aThomas, Patrick, K.1 aSullivan, Pamela, L.1 aMcKnight, Diane, M.1 aMcDowell, William, H.1 aHeindel, Ruth, C1 aJones, Jeremy, B.1 aWollheim, Wilfred1 aAbbott, Benjamin1 aDeegan, Linda1 aCarey, Joanna, C. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GB00767802541nas a2200241 4500008004100000245010600041210006900147260001200216520180200228653001202030653000602042653001802048653001902066653001302085653001902098653000602117653002202123100002202145700002202167700002102189700002402210856006502234 2023 eng d00aNitrogen fixation facilitates stream microbial mat biomass across the McMurdo Dry Valleys, Antarctica0 aNitrogen fixation facilitates stream microbial mat biomass acros c07/20233 a

Nitrogen (N) fixation is a fundamental mechanism by which N enters streams. Yet, because of modern N saturation, it is difficult to study the importance of N-fixation to stream nutrient budgets. Here, we utilized relatively simple and pristine McMurdo Dry Valley streams to investigate the role of N-fixing Nostoc abundance, streamwater dissolved inorganic N (DIN) concentration, and distance from the source glacier in regulating the elemental and isotopic composition of three microbial mat types (black, orange, and green) at the landscape scale. We found Nostoc-based black mats were the most enriched in δ15N, and δ15N signatures of mats increased where Nostoc was abundant, but did not surpass the atmospheric standard (δ15N ≈ 0‰). Furthermore, green and orange mat δ15N signatures became more depleted with increasing DIN, indicating that mats utilize glacial meltwater-sourced N when available. The distance from the source glacier explained limited variability in mat δ15N across sites, indicating the influence of individual stream characteristics on N spiraling. To further explore longitudinal N spiraling processes generating observed δ15Ν patterns, we developed a simple steady-state mathematical model. Analysis of plausible scenarios with this model confirmed that streams both have the capacity to remove allochthonous DIN over the plausible range of inputs, and that internal N sources are required to account for δ15N signatures and observed DIN concentrations at stream outlets. Collectively, these data and modeling results demonstrate that N-fixation exerts substantial influence within and across these streams, and is presumably dependent upon interconnected organic matter reserves, mineralization rates, and geomorphology.

10abiofilm10aC10acyanobacteria10ahyporheic zone10aMCM LTER10amineralization10aN10aP biogeochemistry1 aKohler, Tyler, J.1 aSingley, Joel, G.1 aWlostowski, Adam1 aMcKnight, Diane, M. uhttps://link.springer.com/article/10.1007/s10533-023-01069-002170nas a2200145 4500008004100000022001400041245013800055210006900193260001200262520161600274100002401890700002401914700002501938856006101963 2023 eng d a2169-900300aSpatial patterns of major ions and their relationship to sediment concentration in near surface glacier ice, Taylor Valley Antarctica0 aSpatial patterns of major ions and their relationship to sedimen c03/20243 a

Glaciers form the headwaters of many watersheds and, in arid polar environments, can provide the vast majority of water to downstream systems. Headwater watersheds are critically important for setting the chemistry for downstream systems, yet we know comparatively little about the patterns and processes that generate the geochemical signature of meltwater on glacier surfaces. Here, we focus on glaciers in the McMurdo Dry Valleys of Antarctica, the largest ice-free area on the continent, characterized by alpine glaciers flowing into broad, rocky valleys. We examine patterns from the coast inland, accumulation to ablation zones, laterally across individual glaciers, and through the zone of meltwater generation. We directly compare solute to sediment concentrations, a major source of dissolved solutes. Our findings agree with previous work that the overall meltwater chemistry of a given glacier is a product local sediment sources and of regional wind patterns: foehn winds moving from the ice sheet to the coast and on-shore sea breezes. Further, these patterns hold across an individual glacier. Finally, we find that the ice chemistry and sediment profiles reflect freeze-thaw and melt processes that occur at depth. This indicates that the transport and weathering of sediment in the ice profile likely has a strong influence on supra- and proglacial stream chemistry. This new understanding strengthens connections between physical and geochemical processes in cold-based polar glacier environments and helps us better understand the processes driving landscape and ecosystem connectivity.

1 aBergstrom, Anna, J.1 aWelch, Kathleen, A.1 aGooseff, Michael, N. uhttps://onlinelibrary.wiley.com/doi/10.1029/2022JF00698002259nas a2200289 4500008004100000245009100041210006900132260001200201490000600213520140100219653002301620653001601643653001401659653001001673653001801683100002401701700001701725700002101742700002601763700002601789700001701815700001701832700001801849700002001867700001801887856006401905 2023 eng d00aStrong dispersal limitation of microbial communities at Shackleton Glacier, Antarctica0 aStrong dispersal limitation of microbial communities at Shacklet c01/20230 v83 a

Microbial communities can be structured by both deterministic and stochastic processes, but the relative importance of these processes remains unknown. The ambiguity partly arises from an inability to disentangle soil microbial processes from confounding factors, such as aboveground plant communities or anthropogenic disturbance. In this study, we characterized the relative contributions of determinism and stochasticity to assembly processes of soil bacterial communities across a large environmental gradient of undisturbed Antarctic soils. We hypothesized that harsh soils would impose a strong environmental selection on microbial communities, whereas communities in benign soils would be structured largely by dispersal. Contrary to our expectations, dispersal was the dominant assembly mechanism across the entire soil environmental gradient, including benign environments. The microbial community composition reflects slowly changing soil conditions and dispersal limitation of isolated sites. Thus, stochastic processes, as opposed to deterministic, are primary drivers of soil ecosystem assembly across space at our study site. This is especially surprising given the strong environmental constraints on soil microorganisms in one of the harshest environments on the planet, suggesting that dispersal could be a driving force in microbial community assembly in soils worldwide.

10acommunity assembly10adeterminism10adispersal10aniche10astochasticity1 aLemoine, Nathan, P.1 aAdams, Byron1 aDiaz, Melisa, A.1 aDragone, Nicholas, B.1 aFranco, André, L. C.1 aFierer, Noah1 aLyons, Berry1 aHogg, Ian, D.1 aWall, Diana, H.1 aLurgi, Miguel uhttps://journals.asm.org/doi/full/10.1128/msystems.01254-2202367nas 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.01330-2102315nas a2200265 4500008004100000245009400041210006900135260001200204520148400216653001501700653001701715653002601732653001901758653001701777653001301794653002301807100002101830700002601851700002201877700002401899700002301923700002001946700002501966856005801991 2022 eng d00aIslands in the ice: Potential impacts of habitat transformation on Antarctic biodiversity0 aIslands in the ice Potential impacts of habitat transformation o c07/20223 a

Antarctic biodiversity faces an unknown future with a changing climate. Most terrestrial biota is restricted to limited patches of ice-free land in a sea of ice, where they are adapted to the continent's extreme cold and wind and exploit microhabitats of suitable conditions. As temperatures rise, ice-free areas are predicted to expand, more rapidly in some areas than others. There is high uncertainty as to how species' distributions, physiology, abundance, and survivorship will be affected as their habitats transform. Here we use current knowledge to propose hypotheses that ice-free area expansion (i) will increase habitat availability, though the quality of habitat will vary; (ii) will increase structural connectivity, although not necessarily increase opportunities for species establishment; (iii) combined with milder climates will increase likelihood of non-native species establishment, but may also lengthen activity windows for all species; and (iv) will benefit some species and not others, possibly resulting in increased homogeneity of biodiversity. We anticipate considerable spatial, temporal, and taxonomic variation in species responses, and a heightened need for interdisciplinary research to understand the factors associated with ecosystem resilience under future scenarios. Such research will help identify at-risk species or vulnerable localities and is crucial for informing environmental management and policymaking into the future.

10aAntarctica10abiodiversity10abiotic homogenization10aclimate change10aconnectivity10aice-free10anon-native species1 aLee, Jasmine, R.1 aWaterman, Melinda, J.1 aShaw, Justine, D.1 aBergstrom, Dana, M.1 aLynch, Heather, J.1 aWall, Diana, H.1 aRobinson, Sharon, A. uhttps://onlinelibrary.wiley.com/doi/10.1111/gcb.1633102944nas a2200301 4500008004100000022001400041245009600055210007100151260001200222490000700234520204100241653001702282653001902299653002002318653001402338653002302352653002302375100002602398700001702424700002102441700002402462700002602486700001702512700001702529700001802546700002002564856005802584 2022 eng d a1354-101300aResponse of Antarctic soil fauna to climate‐driven changes since the Last Glacial Maximum0 aResponse of Antarctic soil fauna to climate‐driven changes since c01/20220 v283 a

Understanding how terrestrial biotic communities have responded to glacial recession since the Last Glacial Maximum (LGM) can inform present and future responses of biota to climate change. In Antarctica, the Transantarctic Mountains (TAM) have experienced massive environmental changes associated with glacial retreat since the LGM, yet we have few clues as to how its soil invertebrate-dominated animal communities have responded. Here, we surveyed soil invertebrate fauna from above and below proposed LGM elevations along transects located at 12 features across the Shackleton Glacier region. Our transects captured gradients of surface ages possibly up to 4.5 million years and the soils have been free from human disturbance for their entire history. Our data support the hypothesis that soils exposed during the LGM are now less suitable habitats for invertebrates than those that have been exposed by deglaciation following the LGM. Our results show that faunal abundance, community composition, and diversity were all strongly affected by climate-driven changes since the LGM. Soils more recently exposed by glacial recession (as indicated by distances from present ice surfaces) had higher faunal abundances and species richness than older exposed soils. Higher abundances of the dominant nematode Scottnema were found in older exposed soils, while Eudorylaimus, Plectus, tardigrades, and rotifers preferentially occurred in more recently exposed soils. Approximately 30% of the soils from which invertebrates could be extracted had only Scottnema, and these single-taxon communities occurred more frequently in soils exposed for longer periods of time. Our structural equation modeling of abiotic drivers highlighted soil salinity as a key mediator of Scottnema responses to soil exposure age. These changes in soil habitat suitability and biotic communities since the LGM indicate that Antarctic terrestrial biodiversity throughout the TAM will be highly altered by climate warming.

10abiodiversity10aclimate change10aglacial retreat10anematodes10aShackleton Glacier10asoil invertebrates1 aFranco, André, L. C.1 aAdams, Byron1 aDiaz, Melisa, A.1 aLemoine, Nathan, P.1 aDragone, Nicholas, B.1 aFierer, Noah1 aLyons, Berry1 aHogg, Ian, D.1 aWall, Diana, H. uhttps://onlinelibrary.wiley.com/doi/10.1111/gcb.1594002569nas a2200373 4500008004100000245008100041210006900122260004300191520135400234100001701588700001801605700002201623700002101645700002001666700003001686700002101716700002401737700002301761700001801784700002101802700002301823700002201846700002001868700002301888700002401911700001601935700002301951700002401974700002101998700001902019700001802038700002002056856011902076 2022 eng d00aTen scientific messages on risks and opportunities for life in the Antarctic0 aTen scientific messages on risks and opportunities for life in t bAntarctic Environments Portalc02/20223 a

Initiated by the SCAR scientific research programme “Antarctic Thresholds – Ecosystem Resilience and Adaptation” (AnT-ERA, 2013-2021), 26 experts synthesized knowledge on impacts and risks of climate-change on biological processes and ecosystem functions in the Antarctic. The ten main scientific messages that emerged addressed (1) accelerating marine and terrestrial biogeochemical cycles, (2) response to ocean acidification, (3) ecological changes in climate change hot spots, (4) unexpected dynamism of marine seafloor communities, (5) biodiversity shifts, (6) low temperature limitation of protein synthesis, (7) life intrinsically linked to changing sea ice conditions, (8) pollution, (9) genetically distinct terrestrial populations under threat, and (10) newly discovered habitats. Two-thirds of the literature included in this synthesis was published between 2010 and 2020 and only one-third was published earlier. The fast mounting, recent decadal evidence indicates various Antarctic biological communities now experience climate stress, or will experience such stress in the coming decades. The responses of organisms, ecosystem functions and services to environmental changes are complex and varied. Key knowledge gaps remain and need addressing to adequately assess future prospects for life in the Antarctic.

1 aGutt, Julian1 aIsla, Enrique1 aXavier, José, C.1 aAdams, Byron, J.1 aAhn, In‐Young1 aCheng, C.‐H., Christina1 aColesie, Claudia1 aCummings, Vonda, J.1 aGriffiths, Huw, J.1 aHogg, Ian, D.1 aMcIntyre, Trevor1 aMeiners, Klaus, M.1 aPearce, David, A.1 aPeck, Lloyd, S.1 aPiepenburg, Dieter1 aReisinger, Ryan, R.1 aSaba, Grace1 aSchloss, Irene, R.1 aSignori, Camila, N.1 aSmith, Craig, R.1 aVacchi, Marino1 aVerde, Cinzia1 aWall, Diana, H. uhttps://environments.aq/publications/ten-scientific-messages-on-risks-and-opportunities-for-life-in-the-antarctic/02575nas a2200397 4500008004100000022001400041245006100055210005700116260001200173490000800185520139000193100002701583700002801610700001701638700002401655700003001679700001901709700002201728700002101750700002301771700002201794700002501816700002001841700002201861700002101883700002201904700003101926700002201957700002301979700002202002700002402024700002102048700002202069700003302091856005302124 2022 eng d a0027-842400aThe time is right for an Antarctic biorepository network0 atime is right for an Antarctic biorepository network c12/20220 v1193 a

Antarctica is a central driver of the Earth’s climate and health. The Southern Ocean surrounding Antarctica serves as a major sink for anthropogenic CO2 and heat, and the loss of Antarctic ice sheets contributes significantly to sea level rise and will continue to do so as the loss of ice sheets accelerates, with sufficient water stores to raise sea levels by 58 m. Antarctica's marine environment is home to a number of iconic species, and the terrestrial realm harbors a remarkable oasis for life, much of which has yet to be discovered. Distinctive oceanographic features of the Southern Ocean—including the Antarctic Circumpolar Current, the Antarctic Polar Front, and exceptional depths surrounding the continent—coupled with chronically cold temperatures have fostered the evolution of a vast number of uniquely coldadapted species, many of which are found nowhere else on the Earth. The Antarctic marine biota, for example, displays the highest level of species endemism on the Earth. However, warming, ocean acidification, pollution, and commercial exploitation threaten the integrity of Antarctic ecosystems. Understanding changes in the biota and its capacities for adaptation is imperative for establishing effective policies for mitigating the impacts of climate change and sustaining the Antarctic ecosystems that are vital to global health.

1 aO’Brien, Kristin, M.1 aCrockett, Elizabeth, L.1 aAdams, Byron1 aAmsler, Charles, D.1 aAppiah-Madson, Hannah, J.1 aCollins, Allen1 aDesvignes, Thomas1 aDetrich, William1 aDistel, Daniel, L.1 aEppley, Sarah, M.1 aFrable, Benjamin, W.1 aFranz, Nico, M.1 aGrim, Jeffrey, M.1 aKocot, Kevin, M.1 aMahon, Andrew, R.1 aMayfield-Meyer, Teresa, J.1 aMikucki, Jill, A.1 aMoser, William, E.1 aSchmull, Michaela1 aSeid, Charlotte, A.1 aSmith, Craig, R.1 aTodgham, Anne, E.1 aWatkins-Colwell, Gregory, J. uhttps://www.pnas.org/doi/10.1073/pnas.221280011903115nas a2200517 4500008004100000245008300041210006900124260001200193520161800205653001501823653002101838653002601859653001901885653001301904653001701917653002401934653002301958653001701981653001201998100001702010700001802027700002202045700002102067700002002088700003002108700002102138700002402159700002102183700002302204700001502227700001802242700002102260700002302281700002202304700002002326700002302346700002402369700001602393700002302409700002402432700002102456700001902477700001802496700002002514856006302534 2021 eng d00aAntarctic ecosystems in transition – life between stresses and opportunities0 aAntarctic ecosystems in transition life between stresses and opp c06/20213 a

Important findings from the second decade of the 21st century on the impact of environmental change on biological processes in the Antarctic were synthesised by 26 international experts. Ten key messages emerged that have stakeholder‐relevance and/or a high impact for the scientific community. They address (i) altered biogeochemical cycles, (ii) ocean acidification, (iii) climate change hotspots, (iv) unexpected dynamism in seabed‐dwelling populations, (v) spatial range shifts, (vi) adaptation and thermal resilience, (vii) sea ice related biological fluctuations, (viii) pollution, (ix) endangered terrestrial endemism and (x) the discovery of unknown habitats. Most Antarctic biotas are exposed to multiple stresses and considered vulnerable to environmental change due to narrow tolerance ranges, rapid change, projected circumpolar impacts, low potential for timely genetic adaptation, and migration barriers. Important ecosystem functions, such as primary production and energy transfer between trophic levels, have already changed, and biodiversity patterns have shifted. A confidence assessment of the degree of ‘scientific understanding’ revealed an intermediate level for most of the more detailed sub‐messages, indicating that process‐oriented research has been successful in the past decade. Additional efforts are necessary, however, to achieve the level of robustness in scientific knowledge that is required to inform protection measures of the unique Antarctic terrestrial and marine ecosystems, and their contributions to global biodiversity and ecosystem services.

10aadaptation10abenthic dynamism10abiogeochemical cycles10aclimate change10ainvasion10anew habitats10aocean acidification10aPrimary production10arange shifts10asea ice1 aGutt, Julian1 aIsla, Enrique1 aXavier, José, C.1 aAdams, Byron, J.1 aAhn, In‐Young1 aCheng, C.‐H., Christina1 aColesie, Claudia1 aCummings, Vonda, J.1 adi Prisco, Guido1 aGriffiths, Huw, J.1 aHawes, Ian1 aHogg, Ian, D.1 aMcIntyre, Trevor1 aMeiners, Klaus, M.1 aPearce, David, A.1 aPeck, Lloyd, S.1 aPiepenburg, Dieter1 aReisinger, Ryan, R.1 aSaba, Grace1 aSchloss, Irene, R.1 aSignori, Camila, N.1 aSmith, Craig, R.1 aVacchi, Marino1 aVerde, Cinzia1 aWall, Diana, H. uhttps://onlinelibrary.wiley.com/doi/full/10.1111/brv.1267902809nas a2200337 4500008004100000245012000041210006900161260001200230300001800242490000800260520168500268653002201953653002001975653004901995653001902044653001202063653004302075653001902118653002402137653002102161653003102182100002102213700002402234700002202258700002402280700002402304700002502328700002402353700002502377856006902402 2021 eng d00aDiatoms in hyporheic sediments trace organic matter retention and processing in the McMurdo Dry Valleys, Antarctica0 aDiatoms in hyporheic sediments trace organic matter retention an c02/2021 ae2020JG0060970 v1263 a

In low‐nutrient streams in cold and arid ecosystems, the spiraling of autochthonous particulate organic matter (POM) may provide important nutrient subsidies downstream. Because of its lability and the spatial heterogeneity of processing in hyporheic sediments, the downstream transport and fate of autochthonous POM can be difficult to trace. In Antarctic McMurdo Dry Valley (MDV) streams, any POM retained in the hyporheic zone is expected to be derived from surface microbial mats that contain diatoms with long‐lasting silica frustules. We tested whether diatom frustules can be used to trace the retention of autochthonous POM in the hyporheic zone and whether certain geomorphic locations promote this process. The accumulation of diatom frustules in hyporheic sediments, measured as biogenic silica, was correlated with loss‐on‐ignition organic matter and sorbed ammonium, suggesting that diatoms can be used to identify locations where POM has been retained and processed over long timescales, regardless of whether the POM remains intact. In addition, by modeling the upstream sources of hyporheic diatom assemblages, we found that POM was predominantly derived from N‐fixing microbial mats of the genus Nostoc. In terms of spatial variability, we conclude that the hyporheic sediments adjacent to the stream channel that are regularly inundated by daily flood pulses are where the most POM has been retained over long timescales. Autochthonous POM is retained in hyporheic zones of low‐nutrient streams beyond the MDVs, and we suggest that biogenic silica and diatom composition can be used to identify locations where this transfer is most prevalent.

10abenthic processes10abiogenic silica10abiogeochemical cycles processes and modeling10acarbon cycling10adiatoms10agroundwater/surface water interactions10ahyporheic zone10aMcMurdo Dry Valleys10anitrogen cycling10aparticulate organic matter1 aHeindel, Ruth, C1 aDarling, Joshua, P.1 aSingley, Joel, G.1 aBergstrom, Anna, J.1 aMcKnight, Diane, M.1 aLukkari, Braeden, M.1 aWelch, Kathleen, A.1 aGooseff, Michael, N. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG00609702506nas 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/10.1029/2020JG00605202615nas a2200229 4500008004100000245011400041210006900155260001200224300001600236490000700252520188900259100002102148700002902169700002102198700002002219700002102239700002002260700001802280700001702298700001702315856005302332 2021 eng d00aGeochemical zones and environmental gradients for soils from the central Transantarctic Mountains, Antarctica0 aGeochemical zones and environmental gradients for soils from the c03/2021 a1629 - 16440 v183 a

Previous studies have established links between biodiversity and soil geochemistry in the McMurdo Dry Valleys, Antarctica, where environmental gradients are important determinants of soil biodiversity. However, these gradients are not well established in the central Transantarctic Mountains, which are thought to represent some of the least hospitable Antarctic soils. We analyzed 220 samples from 11 ice-free areas along the Shackleton Glacier (~85°S), a major outlet glacier of the East Antarctic Ice Sheet. We established three zones of distinct geochemical gradients near the head of the glacier (upper), its central part (middle), and at the mouth (lower). The upper zone had the highest water-soluble salt concentrations with total salt concentrations exceeding 80 000 µg g-1, while the lower zone had the lowest water-soluble N:P ratios, suggesting that, in addition to other parameters (such as proximity to water and/or ice), the lower zone likely represents the most favorable ecological habitats. Given the strong dependence of geochemistry on geographic parameters, we developed multiple linear regression and random forest models to predict soil geochemical trends given latitude, longitude, elevation, distance from the coast, distance from the glacier, and soil moisture (variables which can be inferred from remote measurements). Confidence in our random forest model predictions was moderately high with R2 values for total water-soluble salts, water-soluble N:P, ClO4-, and ClO3- of 0.81, 0.88, 0.78, and 0.74, respectively. These modeling results can be used to predict geochemical gradients and estimate salt concentrations for other Transantarctic Mountain soils, information that can ultimately be used to better predict distributions of soil biota in this remote region.

1 aDiaz, Melisa, A.1 aGardner, Christopher, B.1 aWelch, Susan, A.1 aJackson, Andrew1 aAdams, Byron, J.1 aWall, Diana, H.1 aHogg, Ian, D.1 aFierer, Noah1 aLyons, Berry uhttps://bg.copernicus.org/articles/18/1629/2021/02603nas a2200181 4500008004100000245007200041210006900113260001200182300001200194490000800206520196600214100002402180700002402204700001702228700002402245700002402269856012802293 2021 eng d00aGeochemistry of contrasting stream types, Taylor Valley, Antarctica0 aGeochemistry of contrasting stream types Taylor Valley Antarctic c01/2021 a425-4480 v1333 a

The McMurdo Dry Valley region is the largest ice-free area of Antarctica. Ephemeral streams flow here during the austral summer, transporting glacial meltwater to perennially ice-covered, closed basin lakes. The chemistry of 24 Taylor Valley streams was examined over the two-decade period of monitoring from 1993 to 2014, and the geochemical behavior of two streams of contrasting physical and biological character was monitored across the seven weeks of the 2010–2011 flow season. Four species dominate stream solute budgets: HCO3, Ca2+, Na+, and Cl, with SO42–, Mg2+, and K+ present in significantly lesser proportions. All streams contain dissolved silica at low concentrations. Across Taylor Valley, streams are characterized by their consistent anionic geochemical fingerprint of HCO3 > Cl > SO4, but there is a split in cation composition between 14 streams with Ca > Na > Mg > K and 10 streams with Na > Ca > Mg > K.


Andersen Creek is a first-order proglacial stream representative of the 13 short streams that flow <1.5 km from source to gage. Von Guerard is representative of 11 long streams 2–7 km in length characterized by extensive hyporheic zones. Both streams exhibit a strong daily cycle for solute load, temperature, dissolved oxygen, and pH, which vary in proportion to discharge. A well-expressed diurnal co-variation of pH with dissolved oxygen is observed for both streams that reflects different types of biological control. The relative consistency of Von Guerard composition over the summer flow season reflects chemostatic regulation, where water in transient storage introduced during times of high streamflow has an extended opportunity for water-sediment interaction, silicate mineral dissolution, and pore-water exchange.

1 aHarmon, Russell, S.1 aLeslie, Deborah, L.1 aLyons, Berry1 aWelch, Kathleen, A.1 aMcKnight, Diane, M. uhttps://pubs.geoscienceworld.org/gsa/gsabulletin/article/133/1-2/425/587799/Geochemistry-of-contrasting-stream-types-Taylor02981nas a2200253 4500008004100000022001400041245011200055210006900167260001200236300001400248490000700262520216600269653002102435653002602456653002602482100002802508700002202536700002202558700002102580700002202601700001802623700001502641856007102656 2021 eng d a1523-043000aThe magnitude and climate sensitivity of isotopic fractionation from ablation of Antarctic Dry Valley lakes0 amagnitude and climate sensitivity of isotopic fractionation from c12/2021 a352 - 3710 v533 a

There has been extensive research on the effects of evaporation on the isotopic ratio of lacustrine and marine water bodies; however, there are limited data on how ablation or sublimation from lake or sea ice influences the isotopic ratio of the residual water body. This is a challenging problem because there remains uncertainty on the magnitude of fractionation during sublimation and because ablation can involve mixed-phase processes associated with simultaneous sublimation, melting, evaporation, and refreezing. This uncertainty limits the ability to draw quantitative inferences on changing hydrological budgets from stable isotope records in arctic, Antarctic, and alpine lakes. Here, we use in situ measurements of the isotopic ratio of water vapor along with the gradient diffusion method to constrain the isotopic ratio of the ablating ice from two lakes in the McMurdo Dry Valleys, Antarctica. We find that during austral summer, the isotopic fractionation of ablation was insignificant during periods of boundary layer instability that are typical during midday when latent heat is highest. This implies that the loss of mass during these periods did not yield any isotopic enrichment to the residual lake mass. However, fractionation increased after midday when the boundary layer stabilized and the latent heat flux was small. This diurnal pattern was mirrored on synoptic timescales, when following warm and stable conditions latent heat flux was low and dominated by higher fractionation for a few days. We hypothesize that the shifting from negligible to large isotopic fractionation reflects the development and subsequent exhaustion of liquid water on the surface. The results illustrate the complex and nonlinear controls on isotopic fractionation from icy lakes, which implies that the isotopic enrichment from ablation could vary significantly over timescales relevant for changing lake volumes. Future work using water isotope fluxes for longer periods of time and over additional perennial and seasonal ice-covered lake systems is critical for developing models of the isotopic mass balance of arctic and Antarctic lake systems.

10aDry Valley lakes10aisotope fractionation10astable water isotopes1 aBellagamba, Anthony, W.1 aBerkelhammer, Max1 aWinslow, Luke, A.1 aDoran, Peter, T.1 aMyers, Krista, F.1 aDevlin, Shawn1 aHawes, Ian uhttps://www.tandfonline.com/doi/full/10.1080/15230430.2021.200189902329nas a2200193 4500008004100000022001400041245010500055210006900160260001200229300001200241490000700253520164000260100002301900700002601923700001901949700002201968700002601990856011902016 2021 eng d a1527-140400aMeta-analysis of Cryogenian through modern quartz microtextures reveals sediment transport histories0 aMetaanalysis of Cryogenian through modern quartz microtextures r c09/2021 a929-9440 v913 a

Quantitative analysis of quartz microtextures by means of scanning electron microscopy (SEM) can reveal the transport histories of modern and ancient sediments. However, because workers identify and count microtextures differently, it is difficult to directly compare quantitative microtextural data analyzed by different workers. As a result, the defining microtextures of certain transport modes and their probabilities of occurrence are not well constrained. We used principal-component analysis (PCA) to directly compare modern and ancient aeolian, fluvial, and glacial samples from the literature with nine new samples from active aeolian and glacial environments. Our results demonstrate that PCA can group microtextural samples by transport mode and differentiate between aeolian transport and fluvial and glacial transport across studies. The PCA ordination indicates that aeolian samples are distinct from fluvial and glacial samples, which are in turn difficult to disambiguate from each other. Ancient and modern sediments are also shown to have quantitatively similar microtextural relationships. Therefore, PCA may be a useful tool to constrain the ambiguous transport histories of some ancient sediment grains. As a case study, we analyzed two samples with ambiguous transport histories from the Cryogenian Bråvika Member (Svalbard). Integrating PCA with field observations, we find evidence that the Bråvika Member facies investigated here includes aeolian deposition and may be analogous to syn-glacial Marinoan aeolian units including the Bakoye Formation in Mali and the Whyalla Sandstone in South Australia.

1 aReahl, Jocelyn, N.1 aCantine, Marjorie, D.1 aWilcots, Julia1 aMackey, Tyler, J.1 aBergmann, Kristin, D. uhttps://pubs.geoscienceworld.org/jsedres/article/91/9/929/607764/Meta-analysis-of-Cryogenian-through-modern-quartz02579nas a2200397 4500008004100000022001300041245012700054210006900181260001200250300001100262490000600273520134500279653003401624653002501658653003101683653002701714653001801741653001401759100002201773700002401795700002201819700002301841700002301864700001401887700001901901700001601920700002101936700002701957700002601984700001602010700002402026700001602050700002102066700002202087856007202109 2021 eng d a2666900500aPatterns and trends of organic matter processing and transport: Insights from the US Long-term Ecological Research Network0 aPatterns and trends of organic matter processing and transport I c12/2021 a1000250 v23 a

Organic matter (OM) dynamics determine how much carbon is stored in ecosystems, a service that modulates climate. We synthesized research from across the US Long-Term Ecological Research (LTER) Network to assemble a conceptual model of OM dynamics that is consistent with inter-disciplinary perspectives and emphasizes vulnerability of OM pools to disturbance. Guided by this conceptual model, we identified unanticipated patterns and long-term trends in processing and transport of OM emerging from terrestrial, freshwater, wetland, and marine ecosystems. Cross-ecosystem synthesis combined with a survey of researchers revealed several themes: 1) strong effects of climate change on OM dynamics, 2) surprising patterns in OM storage and dynamics resulting from coupling with nutrients, 3) characteristic and often complex legacies of land use and disturbance, 4) a significant role of OM transport that is often overlooked in terrestrial ecosystems, and 5) prospects for reducing uncertainty in forecasting OM dynamics by incorporating the chemical composition of OM. Cross-fertilization of perspectives and approaches across LTER sites and other research networks can stimulate the comprehensive understanding required to support large-scale characterizations of OM budgets and the role of ecosystems in regulating global climate.

10acoupled biogeochemical cycles10across-site synthesis10aorganic matter composition10aorganic matter storage10astabilization10atransport1 aHarms, Tamara, K.1 aGroffman, Peter, M.1 aAluwihare, Lihini1 aCraft, Christopher1 aWieder, William, R1 aHobbie, S1 aBaer, Sara, G.1 aBlair, J.M.1 aFrey, Serita, D.1 aRemucal, Christina, K.1 aRudgers, Jennifer, A.1 aCollins, SL1 aKominoski, John, S.1 aBall, Becky1 aPriscu, John, C.1 aBarrett, John, E. uhttps://www.sciencedirect.com/science/article/pii/S266690052100025302753nas a2200325 4500008004100000022001400041245011500055210007300170260001200243300001800255490000800273520178400281653001002065653001402075653001602089653000802105653001002113653001002123653001402133653001102147100002802158700002102186700003302207700002202240700002202262700002402284700002902308700002102337856006902358 2021 eng d a2169-895300aYear‐round and long‐term phytoplankton dynamics in Lake Bonney, a permanently ice‐covered Antarctic lake0 aYear‐round and long‐term phytoplankton dynamics in Lake Bonney a c04/2021 ae2020JG0059250 v1263 a

Lake Bonney (McMurdo Dry Valleys, east Antarctica) represents a year‐round refugium for life adapted to permanent extreme conditions. Despite intensive research since the 1960s, due to the logistical constraints posed by 4‐months of 24‐h darkness, knowledge of how the resident photosynthetic microorganisms respond to the polar winter is limited. In addition, the lake level has risen by more than 3 m since 2004: impacts of rapid lake level rise on phytoplankton community structure is also poorly understood. From 2004 to 2015 an in situ submersible spectrofluorometer (bbe FluoroProbe) was deployed in Lake Bonney during the austral summer to quantify the vertical structure of four functional algal groups (green algae, mixed algae, and cryptophytes, cyanobacteria). During the 2013–2014 field season the Fluoroprobe was mounted on autonomous cable‐crawling profilers deployed in both the east and west lobes of Lake Bonney, obtaining the first daily phytoplankton profiles through the polar night. Our findings showed that phytoplankton communities were differentially impacted by physical and chemical factors over long‐term versus seasonal time scales. Following a summer of rapid lake level rise (2010–2011), an increase in depth integrated chlorophyll a (chl‐a) occurred in Lake Bonney caused by stimulation of photoautotrophic green algae. Conversely, peaks in chl‐a during the polar night were associated with an increase in mixotrophic haptophytes and cryptophytes. Collectively our data reveal that phytoplankton groups possessing variable trophic abilities are differentially competitive during seasonal and long‐term time scales owing to periods of higher nutrients (photoautotrophs) versus light/energy limitation (mixotrophs).

10aalgae10aAntarctic10afluorometry10aice10alakes10alight10aprofiling10awinter1 aPatriarche, Jeffrey, D.1 aPriscu, John, C.1 aTakacs-Vesbach, Cristina, D.1 aWinslow, Luke, A.1 aMyers, Krista, F.1 aBuelow, Heather, N.1 aMorgan-Kiss, Rachael, M.1 aDoran, Peter, T. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG00592502207nas a2200205 4500008004100000245010800041210006900149260001200218520152500230100001601755700001401771700002301785700001901808700002201827700001401849700001901863700002101882700002901903856006901932 2020 eng d00aChlamydomonas sp. UWO 241 exhibits high cyclic electron flow and rewired metabolism under high salinity0 aChlamydomonas sp UWO 241 exhibits high cyclic electron flow and  c03/20203 a

The Antarctic green alga Chlamydomonas sp. UWO 241 (UWO 241) is adapted to permanent low temperatures, hypersalinity, and extreme shade. one of the most striking phenotypes of UWO 241 is an altered photosystem I (PSI) organization and constitutive PSI cyclic electron flow (CEF). To date, little attention has been paid to CEF during long-term stress acclimation, and the consequences of sustained CEF in UWO 241 are not known. In this study, we combined photobiology, proteomics, and metabolomics to understand the underlying role of sustained CEF in high salinity stress acclimation. High salt-grown UWO 241 exhibited increased thylakoid proton motive flux and an increased capacity for non-photochemical quenching. Under high salt, a significant proportion of the upregulated enzymes were associated with the Calvin Benson Bassham Cycle, carbon storage metabolism, and protein translation. Two key enzymes of the Shikimate pathway, DAHP synthase and chorismate synthase, were also upregulated, as well as indole-3-glycerol phosphate synthase, an enzyme involved in the biosynthesis of L-tryptophan and indole acetic acid. In addition, several compatible solutes (glycerol, proline, and sucrose) accumulated to high levels in high salt-grown UWO 241 cultures. We suggest that UWO 241 maintains constitutively high CEF through the associated PSI-cytochrome b6f supercomplex to support robust growth and strong photosynthetic capacity under a constant growth regime of low temperatures and high salinity.

1 aKalra, Isha1 aWang, Xin1 aCvetkovska, Marina1 aJeong, Jooyeon1 aMcHargue, William1 aZhang, Ru1 aHüner, Norman1 aYuan, Joshua, S.1 aMorgan-Kiss, Rachael, M. uhttp://www.plantphysiol.org/content/early/2020/04/03/pp.19.0128001971nas a2200181 4500008004100000245008500041210006900126260005200195520137400247100002101621700002101642700001801663700002101681700001301702700002001715700002001735856003401755 2020 eng d00aFollowing the Astrobiology Roadmap: Origins, Habitability and Future Exploration0 aFollowing the Astrobiology Roadmap Origins Habitability and Futu aNorfolk, United KingdombCaister Academic Press3 a

Astrobiology asks three fundamental questions as outlined by the NASA Astrobiology Roadmap: 1. How did Life begin and evolve?; Is there Life elsewhere in the Universe?; and, What is the future of Life on Earth? As we gain perspective on how Life on Earth arose and adapted to its many niches, we too gain insight into how a planet achieves habitability. Here on Earth, microbial Life has evolved to exist in a wide range of habitats from aquatic systems to deserts, the human body, and the International Space Station (ISS). Landers, rovers, and orbiter missions support the search for signatures of Life beyond Earth, by generating data on surface and subsurface conditions of other worlds. These have provided evidence for water activity, supporting the potential for extinct or extant Life. To investigate the putative ecologies of these systems, we study extreme environments on Earth. Several locations on our planet provide analog settings to those we have detected or expect to find on neighboring and distant worlds. Whereas, the field of space biology uses the ISS and low gravity analogs to gain insight on how transplanted Earth-evolved organisms will respond to extraterrestrial environments. Modern genomics allows us to chronicle the genetic makeup of such organisms and provides an understanding of how Life adapts to various extreme environments.

1 aO'Rourke, Aubrie1 aZoumplis, Angela1 aWilburn, Paul1 aLee, Michael, D.1 aLee, Zhi1 aVecina, Marissa1 aMercader, Kysha uhttps://www.caister.com/astro02303nas a2200265 4500008004100000245012500041210006900166260001200235520144100247653001901688653002001707653002001727653001901747653002901766100002301795700001801818700001801836700002501854700001901879700001701898700001701915700002001932700002401952856006101976 2020 eng d00aGenetic diversity of soil invertebrates corroborates timing estimates for past collapses of the West Antarctic Ice Sheet0 aGenetic diversity of soil invertebrates corroborates timing esti c08/20203 a

During austral summer field seasons between 1999 and 2018, we sampled at 91 locations throughout southern Victoria Land and along the Transantarctic Mountains for six species of endemic microarthropods (Collembola), covering a latitudinal range from 76.0°S to 87.3°S. We assembled individual mitochondrial cyto-chrome c oxidase subunit 1 (COI) sequences (n = 866) and found high levels of sequence divergence at both small (<10 km) and large (>600 km) spatial scales for four of the six Collembola species. We applied molecular clock estimates and assessed genetic divergences relative to the timing of past glacial cycles, including collapses of the West Antarctic Ice Sheet (WAIS). We found that genetically distinct lineages within three species have likely been isolated for at least 5.54 My to 3.52 My, while the other three species diverged more recently (<2 My). We suggest that Collembola had greater dispersal opportunities under past warmer climates, via flotation along coastal margins. Similarly increased opportunities for dispersal may occur under contemporary climate warming scenarios, which could influence the genetic structure of extant populations. As Collembola are a living record of past landscape evolution within Antarctica, these findings provide biological evidence to support geological and glaciological estimates of historical WAIS dynamics over the last ca. 5 My.

10aclimate change10amicroarthropods10amolecular clock10aphylogeography10aterrestrial biodiversity1 aCollins, Gemma, E.1 aHogg, Ian, D.1 aConvey, Peter1 aSancho, Leopoldo, G.1 aCowan, Don, A.1 aLyons, Berry1 aAdams, Byron1 aWall, Diana, H.1 aGreen, T., G. Allan uhttps://www.pnas.org/content/early/2020/08/19/200792511702540nas a2200289 4500008004100000245012600041210006900167260001200236490000800248520163000256653002101886653001501907653001701922653001501939653002401954653001901978100002101997700002102018700001902039700002402058700001902082700001702101700002402118700001902142700001702161856007202178 2020 eng d00aGeochemistry of aeolian material from the McMurdo Dry Valleys, Antarctica: Insights into Southern Hemisphere dust sources0 aGeochemistry of aeolian material from the McMurdo Dry Valleys An c10/20200 v5473 a

In the Southern Hemisphere, the major sources of dust and other aeolian materials are from Patagonia, South Africa, Australia, and New Zealand. Dust from Patagonia and New Zealand has been identified in ice cores throughout Antarctica, suggesting that during arid and windy periods, such as glacial periods, dust can be entrained and transported onto the continent. However, little information exists on modern Antarctic dust sources, transport, and its role in the Southern Hemisphere dust cycle. We present the first geochemical characterization of aeolian materials collected at five heights (between 5 cm and 100 cm) above the surface in four valleys within the McMurdo Dry Valleys, the largest ice-free area in Antarctica. Our mineralogy data indicate that these materials are primarily derived from local rocks of the McMurdo Volcanics, Ferrar Dolerite, Beacon Sandstone and Granite Harbor Intrusives, with varying contributions of each rock type dependent on the valley location. While major oxide, trace element and rare earth element data show that low elevation and coastal locations (with respect to the Ross Sea) are dominated by local sources, high elevation and inland locations have accumulated both local materials and dust from other distant Southern Hemisphere sources. This far-traveled material may not be accumulating today, but represents a paleo source that is resuspended from the soils. By geochemically “fingerprinting” aeolian materials from the MDV, we can better inform future studies on the transport of materials within Antarctica and between Southern Hemisphere land masses.

10aaeolian material10aAntarctica10amajor oxides10amineralogy10arare earth elements10atrace elements1 aDiaz, Melisa, A.1 aWelch, Susan, A.1 aSheets, J., M.1 aWelch, Kathleen, A.1 aKhan, Alia, L.1 aAdams, Byron1 aMcKnight, Diane, M.1 aCary, Craig, S1 aLyons, Berry uhttps://www.sciencedirect.com/science/article/pii/S0012821X2030404003683nas a2200997 4500008004100000245008200041210006900123260001200192490000600204520084100210100002601051700001901077700002001096700001401116700002501130700002501155700001701180700001701197700001901214700002601233700002301259700002701282700002301309700002101332700003101353700001801384700002101402700002001423700003001443700001501473700002001488700001901508700002501527700002301552700001901575700002101594700001701615700002201632700002101654700002601675700002301701700001101724700001701735700002201752700002101774700003101795700002401826700002201850700001501872700002201887700001801909700001701927700002501944700002201969700001901991700002702010700001602037700001802053700002202071700003202093700002302125700002302148700002002171700002202191700002002213700002702233700001802260700002102278700001902299700002302318700001502341700002302356700002202379700002402401700002102425700002302446700002102469700001802490700001802508700001902526700001402545700002802559700001702587700002702604856005402631 2020 eng d00aA global database of soil nematode abundance and functional group composition0 aglobal database of soil nematode abundance and functional group  c03/20200 v73 a

As the most abundant animals on earth, nematodes are a dominant component of the soil community. they play critical roles in regulating biogeochemical cycles and vegetation dynamics within and across landscapes and are an indicator of soil biological activity. Here, we present a comprehensive global dataset of soil nematode abundance and functional group composition. This dataset includes 6,825 georeferenced soil samples from all continents and biomes. For geospatial mapping purposes these samples are aggregated into 1,933 unique 1-km pixels, each of which is linked to 73 global environmental covariate data layers. Altogether, this dataset can help to gain insight into the spatial distribution patterns of soil nematode abundance and community composition, and the environmental drivers shaping these patterns.

1 avan den Hoogen, Johan1 aGeisen, Stefan1 aWall, Diana, H.1 aWardle, D1 aTraunspurger, Walter1 ade Goede, Ron, G. M.1 aAdams, Byron1 aAhmad, Wasim1 aFerris, Howard1 aBardgett, Richard, D.1 aBonkowski, Michael1 aCampos-Herrera, Raquel1 aCares, Juvenil, E.1 aCaruso, Tancredi1 aCaixeta, Larissa, de Brito1 aChen, Xiaoyun1 aCosta, Sofia, R.1 aCreamer, Rachel1 aCastro, José, da Cunha e1 aDam, Marie1 aDjigal, Djibril1 aEscuer, Miguel1 aGriffiths, Bryan, S.1 aGutiérrez, Carmen1 aHohberg, Karin1 aKalinkina, Daria1 aKardol, Paul1 aKergunteuil, Alan1 aKorthals, Gerard1 aKrashevska, Valentyna1 aKudrin, Alexey, A.1 aLi, Qi1 aLiang, Wenju1 aMagilton, Matthew1 aMarais, Mariette1 aMartín, José, Antonio Ro1 aMatveeva, Elizaveta1 aMayad, El, Hassan1 aMzough, E.1 aMulder, Christian1 aMullin, Peter1 aNeilson, Roy1 aNguyen, T., A. Duong1 aNielsen, Uffe, N.1 aOkada, Hiroaki1 aRius, Juan, Emilio Pal1 aPan, Kaiwen1 aPeneva, Vlada1 aPellissier, Loïc1 ada Silva, Julio, Carlos Per1 aPitteloud, Camille1 aPowers, Thomas, O.1 aPowers, Kirsten1 aQuist, Casper, W.1 aRasmann, Sergio1 aMoreno, Sara, Sánchez1 aScheu, Stefan1 aSetälä, Heikki1 aSushchuk, Anna1 aTiunov, Alexei, V.1 aTrap, Jean1 aVestergård, Mette1 aVillenave, Cecile1 aWaeyenberge, Lieven1 aWilschut, Rutger1 aWright, Daniel, G.1 aKeith, Aidan, M.1 aYang, Jiue-in1 aSchmidt, Olaf1 aBouharroud, R.1 aFerji, Z.1 avan der Putten, Wim, H.1 aRouth, Devin1 aCrowther, Thomas, Ward uhttps://www.nature.com/articles/s41597-020-0437-302368nas a2200229 4500008004100000245007900041210006900120260001200189520162900201653002401830653001301854653002101867653002001888653001401908653002501922100002401947700002501971700002201996700002302018700002402041856007302065 2020 eng d00aNutrient uptake in the supraglacial stream network of an Antarctic glacier0 aNutrient uptake in the supraglacial stream network of an Antarct c08/20203 a

In polar regions, where many glaciers are cold‐based (frozen to their beds), biological communities on the glacier surface can modulate and transform nutrients, controlling downstream delivery. However, it remains unclear whether supraglacial streams are nutrient sinks or sources and the rates of nutrient processing. In order to test this, we conducted tracer‐injections in three supraglacial streams (62 to 123 m long) on Canada Glacier in the Taylor Valley, of the McMurdo Dry Valleys, Antarctica. We conducted a series of additions including: nitrate (N), N + phosphate (P), N+ P + glucose (C), and N+C. In two reaches, N‐only additions resulted in N uptake. The third reach showed net N release during the N‐only addition, but high N uptake in the N+P addition, indicating P‐limitation or N+P co‐limitation. Co‐injecting C did not increase N‐uptake. Additionally, in these systems at low N concentrations the streams can be a net source of nitrogen. We confirmed these findings using laboratory‐based nutrient incubation experiments on sediment collected from stream channels on Canada Glacier and two other glaciers in the Taylor Valley. Together, these results suggest there is active biological processing of nutrients occurring in these supraglacial streams despite low sediment cover, high flow velocities and cold temperatures, modifying the input signals to proglacial streams. As glaciers world‐wide undergo rapid change, these findings further our understanding of how melt generated on glacier surfaces set the initial nutrient signature for subglacial and downstream environments.

10aMcMurdo Dry Valleys10anitrogen10anutrient tracers10anutrient uptake10asediments10asupraglacial streams1 aBergstrom, Anna, J.1 aGooseff, Michael, N.1 aSingley, Joel, G.1 aCohen, Matthew, J.1 aWelch, Kathleen, A. uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG00567902966nas a2200205 4500008004100000245011200041210006900153260001200222490000600234520228000240100002102520700002202541700002302563700002602586700002102612700001502633700002402648700001702672856007102689 2020 eng d00aSilicon isotopes reveal a non-glacial source of silicon to Crescent Stream, McMurdo Dry Valleys, Antarctica0 aSilicon isotopes reveal a nonglacial source of silicon to Cresce c06/20200 v83 a

In high latitude environments, silicon is supplied to river waters by both glacial and non-glacial chemical weathering. The signal of these two end-members is often obscured by biological uptake and/or groundwater input in the river catchment. McMurdo Dry Valleys streams in Antarctica have no deep groundwater input, no connectivity between streams and no surface vegetation cover, and thus provide a simplified system for us to constrain the supply of dissolved silicon (DSi) to rivers from chemical weathering in a glacial environment. Here we report dissolved Si concentrations, germanium/silicon ratios (Ge/Si) and silicon isotope compositions (δ30SiDSi) in Crescent Stream, McMurdo Dry Valleys for samples collected between December and February in the 2014−2015, 2015−2016, and 2016−2017 austral seasons. The δ30SiDSi compositions and DSi concentrations are higher than values reported in wet-based glacial meltwaters, and form a narrow cluster within the range of values reported for permafrost dominated Arctic Rivers. High δ30SiDSi compositions, ranging from +0.90‰ to +1.39‰, are attributed to (i) the precipitation of amorphous silica during freezing of waters in isolated pockets of the hyporheic zone in the winter and the release of Si from unfrozen pockets during meltwater-hyporheic zone exchange in the austral summer, and (ii) additional Si isotope fractionation via long-term Si uptake in clay minerals and seasonal Si uptake into diatoms superimposed on this winter-derived isotope signal. There is no relationship between δ30SiDSi compositions and DSi concentrations with seasonal and daily discharge, showing that stream waters contain DSi that is in equilibrium with the formation of secondary Si minerals in the hyporheic zone. We show that δ30SiDSi compositions can be used as tracers of silicate weathering in the hyporheic zone and possible tracers of freeze-thaw conditions in the hyporheic zone. This is important in the context of the ongoing warming in McMurdo Dry Valleys and the supply of more meltwaters to the hyporheic zone of McMurdo Dry Valley streams.

1 aHirst, Catherine1 aOpfergelt, Sophie1 aGaspard, François1 aHendry, Katharine, R.1 aHatton, Jade, E.1 aWelch, Sue1 aMcKnight, Diane, M.1 aLyons, Berry uhttps://www.frontiersin.org/articles/10.3389/feart.2020.00229/full02674nas a2200253 4500008004100000245007700041210006900118260001200187490000600199520187800205100002102083700002602104700002102130700002202151700001902173700002502192700002102217700002202238700001702260700002302277700002502300700002402325856007102349 2020 eng d00aSilicon isotopic composition of dry and wet-based glaciers in Antarctica0 aSilicon isotopic composition of dry and wetbased glaciers in Ant c07/20200 v83 a

Glaciers and ice sheets export significant amounts of silicon (Si) to downstream ecosystems, impacting local and potentially global biogeochemical cycles. Recent studies have shown Si in Arctic glacial meltwaters to have an isotopically distinct signature when compared to non-glacial rivers. This is likely linked to subglacial weathering processes and mechanochemical reactions. However, there are currently no silicon isotope (δ30Si) data available from meltwater streams in Antarctica, limiting the current inferences on global glacial silicon isotopic composition and its drivers. To address this gap, we present dissolved silicon (DSi), δ30SiDSi, and major ion data from meltwater streams draining a polythermal glacier in the region of the West Antarctic Peninsula (WAP; King George Island) and a cold-based glacier in East Antarctica [Commonwealth Stream, McMurdo Dry Valleys (MDV)]. These data, alongside other global datasets, improve our understanding of how contrasting glacier thermal regime can impact upon Si cycling and therefore the δ30SiDSi composition. We find a similar δ30SiDSi composition between the two sites, with the streams on King George Island varying between -0.23 and +1.23‰ and the Commonwealth stream varying from -0.40 to +1.14‰. However, meltwater streams in King George Island have higher DSi concentrations, and the two glacial systems exhibit opposite DSi – δ30SiDSi trends. These contrasts likely result from differences in weathering processes, specifically the role of subglacial processes (King George Island) and, supraglacial processes followed by in-stream weathering in hyporheic zones (Commonwealth Stream). These findings are important when considering likely changes in nutrient fluxes from Antarctic glaciers under climatic warming scenarios and consequent shifts in glacial thermal regimes.

1 aHatton, Jade, E.1 aHendry, Katharine, R.1 aHirst, Catherine1 aOpfergelt, Sophie1 aHenkel, Susann1 aSilva-Busso, Adrián1 aWelch, Susan, A.1 aWadham, Jemma, L.1 aLyons, Berry1 aBagshaw, Elizabeth1 aStaubwasser, Michael1 aMcKnight, Diane, M. uhttps://www.frontiersin.org/articles/10.3389/feart.2020.00286/full01789nas a2200205 4500008004100000245008500041210006900126260001200195520112400207653001601331653001801347653001001365653001501375653001601390100001901406700002101425700002201446700002101468856009401489 2020 eng d00aSubglacial brine flow and wind-induced internal waves in Lake Bonney, Antarctica0 aSubglacial brine flow and windinduced internal waves in Lake Bon c02/20203 a

Brine beneath Taylor Glacier has been proposed to enter the proglacial west lobe of Lake Bonney (WLB) as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the geochemistry of the water column of WLB. Year-round measurements from this study are the first to definitively identify brine intrusions from a subglacial entry point into WLB. Furthermore, we excluded input from Blood Falls by focusing on winter dynamics when the absence of an open water moat prevents surface brine entry. Due to the extremely high salinities below the chemocline in WLB, density stratification is dominated by salinity, and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude into the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. High-resolution measurements also reveal under-ice internal waves associated with katabatic wind events, a novel finding that challenges long-held assumptions about the stability of the WLB water column.

10aDry valleys10ahypersalinity10alakes10aproglacial10atemperature1 aLawrence, Jade1 aDoran, Peter, T.1 aWinslow, Luke, A.1 aPriscu, John, C. uhttps://www.cambridge.org/core/services/aop-cambridge-core/content/view/S095410202000003602684nas a2200265 4500008004100000022001400041245014900055210006900204260001200273490000600285520185300291653001502144653002502159653000902184653001802193653001702211100001502228700001802243700001602261700001202277700001402289700002102303700002902324856006502353 2019 eng d a0166-859500aThe Antarctic psychrophiles Chlamydomonas spp. UWO241 and ICE-MDV exhibit differential restructuring of photosystem I in response to iron0 aAntarctic psychrophiles iChlamydomonasi spp UWO241 and ICEMDV ex c02/20190 v93 a

Chlamydomonas sp. UWO241 is a psychrophilic alga isolated from the deep photic zone of a perennially ice-covered Antarctic lake (east lobe Lake Bonney, ELB). Past studies have shown that C. sp. UWO241 exhibits constitutive downregulation of photosystem I (PSI) and high rates of PSI-associated cyclic electron flow (CEF). Iron levels in ELB are in the nanomolar range leading us to hypothesize that the unusual PSI phenotype of C. sp. UWO241 could be a response to chronic Fe-deficiency. We studied the impact of Fe availability in C. sp. UWO241, a mesophile, C. reinhardtii SAG11-32c, as well as a psychrophile isolated from the shallow photic zone of ELB, Chlamydomonas sp. ICE-MDV. Under Fe-deficiency, PsaA abundance and levels of photooxidizable P700 (ΔA820/A820) were reduced in both psychrophiles relative to the mesophile. Upon increasing Fe, C. sp. ICE-MDV and C. reinhardtii exhibited restoration of PSI function, while C. sp. UWO241 exhibited only moderate changes in PSI activity and lacked almost all LHCI proteins. Relative to Fe-excess conditions (200 μM Fe2+), C. sp. UWO241 grown in 18 μM Fe2+ exhibited downregulation of light harvesting and photosystem core proteins, as well as upregulation of a bestrophin-like anion channel protein and two CEF-associated proteins (NdsS, PGL1). Key enzymes of starch synthesis and shikimate biosynthesis were also upregulated. We conclude that in response to variable Fe availability, the psychrophile C. sp. UWO241 exhibits physiological plasticity which includes restructuring of the photo-chemical apparatus, increased PSI-associated CEF, and shifts in downstream carbon metabolism toward storage carbon and secondary stress metabolites.

10aAntarctica10aCyclic electron flow10aIron10aPhotosystem I10aPsychrophile1 aCook, Greg1 aTeufel, Amber1 aKalra, Isha1 aLi, Wei1 aWang, Xin1 aPriscu, John, C.1 aMorgan-Kiss, Rachael, M. uhttps://link.springer.com/article/10.1007/s11120-019-00621-002353nas a2200397 4500008004100000245012200041210006900163260001200232490000600244520115100250100002101401700002501422700002101447700002101468700001401489700002201503700001701525700002201542700001701564700002001581700002001601700002401621700002201645700001901667700002401686700002401710700001701734700002301751700002001774700001801794700002401812700002201836700002401858700001901882856005401901 2019 eng d00aBiotic interactions are an unexpected yet critical control on the complexity of an abiotically driven polar ecosystem0 aBiotic interactions are an unexpected yet critical control on th c02/20190 v23 a

Abiotic and biotic factors control ecosystem biodiversity, but their relative contributions remain unclear. The ultraoligotrophic ecosystem of the Antarctic Dry Valleys, a simple yet highly heterogeneous ecosystem, is a natural laboratory well-suited for resolving the abiotic and biotic controls of community structure. We undertook a multidisciplinary investigation to capture ecologically relevant biotic and abiotic attributes of more than 500 sites in the Dry Valleys, encompassing observed landscape heterogeneities across more than 200 km2. Using richness of autotrophic and heterotrophic taxa as a proxy for functional complexity, we linked measured variables in a parsimonious yet comprehensive structural equation model that explained significant variations in biological complexity and identified landscape-scale and fine-scale abiotic factors as the primary drivers of diversity. However, the inclusion of linkages among functional groups was essential for constructing the best-fitting model. Our findings support the notion that biotic interactions make crucial contributions even in an extremely simple ecosystem.

1 aLee, Charles, K.1 aLaughlin, Daniel, C.1 aBottos, Eric, M.1 aCaruso, Tancredi1 aJoy, Kurt1 aBarrett, John, E.1 aBrabyn, Lars1 aNielsen, Uffe, N.1 aAdams, Byron1 aWall, Diana, H.1 aHopkins, D., W.1 aPointing, Steve, B.1 aMcDonald, Ian, R.1 aCowan, Don, A.1 aBanks, Jonathan, C.1 aStichbury, Glen, A.1 aJones, Irfon1 aZawar-Reza, Peyman1 aKaturji, Marwan1 aHogg, Ian, D.1 aSparrow, Ashley, D.1 aStorey, Bryan, C.1 aGreen, T., G. Allan1 aCary, Craig, S uhttps://www.nature.com/articles/s42003-018-0274-502485nas a2200229 4500008004100000245009100041210006900132260001200201490000600213520181500219653001302034653002802047653001102075653001302086653001002099653002102109653002102130653002502151100001702176700002002193856004202213 2019 eng d00aBiotic interactions in experimental Antarctic soil microcosms vary with abiotic stress0 aBiotic interactions in experimental Antarctic soil microcosms va c08/20190 v33 a

Biotic interactions structure ecological communities but abiotic factors affect the strength of these relationships. These interactions are difficult to study in soils due to their vast biodiversity and the many environmental factors that affect soil species. The McMurdo Dry Valleys (MDV), Antarctica, are relatively simple soil ecosystems compared to temperate soils, making them an excellent study system for the trophic relationships of soil. Soil microbes and relatively few species of nematodes, rotifers, tardigrades, springtails, and mites are patchily distributed across the cold, dry landscape, which lacks vascular plants and terrestrial vertebrates. However, glacier and permafrost melt are expected to cause shifts in soil moisture and solutes across this ecosystem. To test how increased moisture and salinity affect soil invertebrates and their biotic interactions, we established a laboratory microcosm experiment (4 community × 2 moisture × 2 salinity treatments). Community treatments were: (1) Bacteria only (control), (2) Scottnema (S. lindsayae + bacteria), (3) Eudorylaimus (E. antarcticus + bacteria), and (4) Mixed (S. lindsayae + E. antarcticus + bacteria). Salinity and moisture treatments were control and high. High moisture reduced S. lindsayae adults, while high salinity reduced the total S. lindsayae population. We found that S. lindsayae exerted top-down control over soil bacteria populations, but this effect was dependent on salinity treatment. In the high salinity treatment, bacteria were released from top-down pressure as S. lindsayae declined. Ours was the first study to empirically demonstrate, although in lab microcosm conditions, top-down control in the MDV soil food web.

10abacteria10abiological interactions10adesert10anematode10apolar10asoil communities10atop-down effects10atrophic interactions1 aShaw, Ashley1 aWall, Diana, H. uhttps://www.mdpi.com/2571-8789/3/3/5701931nas a2200229 4500008004100000245010800041210006900149260001200218490000700230520115400237100002101391700001701412700001701429700002401446700002401470700001601494700001601510700001701526700001501543700002301558856012001581 2019 eng d00aDiurnal chemistry of two contrasting stream types, Taylor Valley, McMurdo Dry Valley Region, Antarctica0 aDiurnal chemistry of two contrasting stream types Taylor Valley  c06/20190 v983 a

Numerous ephemeral streams flow within the McMurdo Dry Valley Region of Antarctica that transport glacial meltwater to perennially ice-covered, closed-basin lakes during the austral summer. The diurnal behavior for two Taylor Valley streams of different character was examined during the summer of 2010-11. Andersen Creek is a short, 1st-order proglacial stream, whereas Von Guerard Stream is a long, high-order stream with an extensive hyporheic zone that has a substantial cyanobacterial algal mat community in its middle reaches. Both streams display strong daily cycles for temperature, electrical conductivity, dissolved oxygen, and pH. Conductivity varies in concert with flow, with solute dilution occurring during the daily high-flow pulse. Dissolved oxygen co-varies strongly with pH at Andersen Creek but not for Von Guerard Stream. Each stream has a distinct geochemical character that for Andersen Creek is a direct reflection of its glacial source, unmodified by secondary effects, whereas that for Von Guerard Stream is modulated by its resident algal mat community and through extensive hyporheic zone interaction and exchange.

1 aHarmon, Mark, E.1 aLeslie, D.L.1 aLyons, Berry1 aWelch, Kathleen, A.1 aMcKnight, Diane, M.1 aChudaev, O.1 aKharaka, Y.1 aHarmon, R.S.1 aMillot, R.1 aShouakar-Stash, O. uhttps://www.e3s-conferences.org/articles/e3sconf/abs/2019/24/e3sconf_wri-162018_01020/e3sconf_wri-162018_01020.html02504nas a2200229 4500008004100000245007200041210006700113260001200180490000800192520178600200100001701986700002202003700002202025700002402047700001502071700002902086700002502115700002102140700002002161700002002181856007302201 2019 eng d00aThe Geochemistry of Englacial Brine From Taylor Glacier, Antarctica0 aGeochemistry of Englacial Brine From Taylor Glacier Antarctica c03/20190 v1243 a

Blood Falls is a hypersaline, iron‐rich discharge at the terminus of the Taylor Glacier in the McMurdo Dry Valleys, Antarctica. In November 2014, brine in a conduit within the glacier was penetrated and sampled using clean‐entry techniques and a thermoelectric melting probe called the IceMole. We analyzed the englacial brine sample for filterable iron (fFe), total Fe, major cations and anions, nutrients, organic carbon, and perchlorate. In addition, aliquots were analyzed for minor and trace elements and isotopes including δD and δ18O of water, δ34S and δ18O of sulfate, 234U, 238U, δ11B, 87Sr/86Sr, and δ81Br. These measurements were made in order to (1) determine the source and geochemical evolution of the brine and (2) compare the chemistry of the brine to that of nearby hypersaline lake waters and previous supraglacially sampled collections of Blood Falls outflow that were interpreted as end‐member brines. The englacial brine had higher Cl− concentrations than the Blood Falls end‐member outflow; however, other constituents were similar. The isotope data indicate that the water in the brine is derived from glacier melt. The H4SiO4 concentrations and U and Sr isotope suggest a high degree of chemical weathering products. The brine has a low N:P ratio of ~7.2 with most of the dissolved inorganic nitrogen in the form of NH4+. Dissolved organic carbon concentrations are similar to end‐member outflow values. Our results provide strong evidence that the original source of solutes in the brine was ancient seawater, which has been modified with the addition of chemical weathering products.

1 aLyons, Berry1 aMikucki, Jill, A.1 aGerman, Laura, A.1 aWelch, Kathleen, A.1 aWelch, Sue1 aGardner, Christopher, B.1 aTulaczyk, Slawek, M.1 aPettit, Erin, C.1 aKowalski, Julia1 aDachwald, Bernd uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JG00441102216nas a2200193 4500008004100000245012200041210006900163260001200232520155300244653001501797653001701812653002101829653002901850653001801879100002101897700001501918700001701933856007201950 2019 eng d00aThe geochemistry of glacial deposits in Taylor Valley, Antarctica: Comparison to upper continental crustal abundances0 ageochemistry of glacial deposits in Taylor Valley Antarctica Com c05/20193 a

Wet-based glacial deposits have been used traditionally as an analog for upper continental crust (UCC) abundances. To provide more information on the validity of using glacial deposits from wet-based glaciers, samples deposited by the dry-based polar glaciers located in Taylor Valley, Antarctica, were collected. Stream channel sediments, comprised of igneous, metamorphic, and sedimentary rocks initially deposited as glacial tills by polar glaciers, were analyzed by XRF, ICP-MS, and SEM. Based on the Chemical Index of Alteration values and A–CN–K ternary diagram, there are low levels of chemical weathering in these tills. Additionally, major and trace element geochemical data are compared to the average UCC values. The observed discrepancies between the mean UCC and Antarctic samples develop from the existence of mafic components, most likely the McMurdo Volcanic Group and Ferrar Dolerite, being present in the Taylor Valley tills. Even though the mafic material typically comprises 3–7% of the till, the volcanic rocks have a significant influence on the tills’ bulk geochemistry. The existence of this mafic fraction in the dry-based glacial tills results from the reduced rate of weathering, as compared to wet-based glaciers. Geochemical analyses of the dry-based glacial tills in polar deserts, such as those found in Taylor Valley, may provide a better representative composition of the original material than wet-based glaciers and need to be incorporated into upper continental crust calculations.

10aAntarctica10ageochemistry10aglacial deposits10apolar dry-based glaciers10aTaylor Valley1 aDowling, Carolyn1 aWelch, Sue1 aLyons, Berry uhttps://www.sciencedirect.com/science/article/pii/S088329271930124602639nas a2200301 4500008004100000245008400041210006900125260001200194520169800206653001501904653002101919653002401940653002701964653001301991100002102004700002602025700001702051700001602068700002502084700002502109700001702134700002202151700002302173700002002196700002402216700002402240856007302264 2019 eng d00aThe hydroecology of an ephemeral wetland in the McMurdo Dry Valleys, Antarctica0 ahydroecology of an ephemeral wetland in the McMurdo Dry Valleys  c11/20193 a

The McMurdo Dry Valleys (MDV) is a polar desert on the coast of East Antarctica where ephemeral wetlands become hydrologically active during warm and sunny summers when sub‐surface flows are generated from melting snowfields. To understand the structure and function of polar wetland ecosystems, we investigated the hydroecology of one such wetland, the Wormherder Creek wetland, during the warm and sunny summer of 2008 – 2009, when the wetland was hydrologically reactivated. Conservative tracer (LiCl) was injected for a 2‐hour period into a stream above the wetland to determine flow path orientations and hydrologic residence times. Tracer results indicated that surface water is rapidly exchanged with wetland groundwater and wetland residence times may exceed two austral summers. Major ion concentrations were uniform in samples from surface water and shallow groundwater throughout the wetland. Microbial mats in the wetland had high autotrophic index values (the ratios of chlorophyll a [Chl‐a]/ash‐free dry mass [AFDM]), ranging from 9‐38 μg Chl‐a/mg AFDM, indicative of actively photosynthesizing mat communities. The diatom communities in the mats were relatively uniform compared to those in mats from regularly flowing MDV streams, with four endemic and one widespread diatom taxa of the genus Luticola accounting for an average of 86% of the community. These results indicate that the hydrologic characteristics of the wetland contribute to uniform geochemical conditions. In turn, uniform geochemical conditions may explain the high autotrophic index values of the microbial mats and relatively low spatial variation of the diatom community.

10aAntarctica10adesert hydrology10adiatom biodiversity10ahyporheic interactions10awetlands1 aWlostowski, Adam1 aSchulte, Nicholas, O.1 aAdams, Byron1 aBall, Becky1 aEsposito, Rhea, M.M.1 aGooseff, Michael, N.1 aLyons, Berry1 aNielsen, Uffe, N.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aWelch, Kathleen, A.1 aMcKnight, Diane, M. uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JG00515301860nas a2200253 4500008004100000245011500041210006900156260001200225490000600237520106300243100002101306700001801327700002201345700002101367700002101388700002001409700001901429700002201448700002401470700002201494700002001516700001701536856005301553 2019 eng d00aNematodes in a polar desert reveal the relative role of biotic interactions in the coexistence of soil animals0 aNematodes in a polar desert reveal the relative role of biotic i c02/20190 v23 a

Abiotic factors are major determinants of soil animal distributions and their dominant role is pronounced in extreme ecosystems, with biotic interactions seemingly playing a minor role. We modelled co-occurrence and distribution of the three nematode species that dominate the soil food web of the McMurdo Dry Valleys (Antarctica). Abiotic factors, other biotic groups, and autocorrelation all contributed to structuring nematode species distributions. However, after removing their effects, we found that the presence of the most abundant nematode species greatly, and negatively, affected the probability of detecting one of the other two species. We observed similar patterns in relative abundances for two out of three pairs of species. Harsh abiotic conditions alone are insufficient to explain contemporary nematode distributions whereas the role of negative biotic interactions has been largely underestimated in soil. The future challenge is to understand how the effects of global change on biotic interactions will alter species coexistence.

1 aCaruso, Tancredi1 aHogg, Ian, D.1 aNielsen, Uffe, N.1 aBottos, Eric, M.1 aLee, Charles, K.1 aHopkins, D., W.1 aCary, Craig, S1 aBarrett, John, E.1 aGreen, T., G. Allan1 aStorey, Bryan, C.1 aWall, Diana, H.1 aAdams, Byron uhttp://www.nature.com/articles/s42003-018-0260-y01888nas a2200301 4500008004100000245004500041210004100086260001200127300001300139490000600152520103800158100001501196700002301211700002801234700002401262700002201286700002501308700001401333700002301347700002401370700002201394700002001416700002601436700001601462700002301478700001601501856006901517 2019 eng d00aThe polar regions in a 2°C warmer world0 apolar regions in a 2°C warmer world c12/2019 aeaaw98830 v53 a

Over the past decade, the Arctic has warmed by 0.75°C, far outpacing the global average, while Antarctic tem- peratures have remained comparatively stable. As Earth approaches 2°C warming, the Arctic and Antarctic may reach 4°C and 2°C mean annual warming, and 7°C and 3°C winter warming, respectively. Expected consequences of increased Arctic warming include ongoing loss of land and sea ice, threats to wildlife and traditional human livelihoods, increased methane emissions, and extreme weather at lower latitudes. With low biodiversity, Antarctic ecosystems may be vulnerable to state shifts and species invasions. Land ice loss in both regions will contribute substantially to global sea level rise, with up to 3 m rise possible if certain thresholds are crossed. Mitigation efforts can slow or reduce warming, but without them northern high latitude warming may accelerate in the next two to four decades. International cooperation will be crucial to foreseeing and adapting to expected changes.

1 aPost, Eric1 aAlley, Richard, B.1 aChristensen, Torben, R.1 aMacias-Fauria, Marc1 aForbes, Bruce, C.1 aGooseff, Michael, N.1 aIler, Amy1 aKerby, Jeffrey, T.1 aLaidre, Kristin, L.1 aMann, Michael, E.1 aOlofsson, Johan1 aStroeve, Julienne, C.1 aUlmer, Fran1 aVirginia, Ross, A.1 aWang, Muyin uhttp://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aaw988303892nas a2200949 4500008004100000245007900041210006900120260001200189490000800201520116600209100002601375700001901401700001701420700001901437700002501456700001401481700002501495700001701520700001701537700002601554700002601580700002301606700002701629700002301656700002101679700003101700700001801731700002101749700002001770700003001790700001501820700002001835700001901855700002501874700002301899700001901922700002101941700001701962700002201979700002102001700002602022700002302048700001102071700001702082700002202099700002102121700003102142700002402173700002202197700002202219700001802241700001702259700002502276700002202301700001902323700002702342700001602369700001802385700002202403700003202425700002302457700002302480700002002503700002202523700002002545700002702565700001802592700002102610700001902631700002302650700001502673700002202688700002302710700002202733700002402755700002002779700002102799700002302820700001802843700002702861856005402888 2019 eng d00aSoil nematode abundance and functional group composition at a global scale0 aSoil nematode abundance and functional group composition at a gl c08/20190 v5723 a

Soil organisms are a crucial part of the terrestrial biosphere. Despite their importance for ecosystem functioning, few quantitative, spatially explicit models of the active belowground community currently exist. In particular, nematodes are the most abundant animals on Earth, filling all trophic levels in the soil food web. Here we use 6,759 georeferenced samples to generate a mechanistic understanding of the patterns of the global abundance of nematodes in the soil and the composition of their functional groups. The resulting maps show that 4.4 ± 0.64 × 1020 nematodes (with a total biomass of approximately 0.3 gigatonnes) inhabit surface soils across the world, with higher abundances in sub-Arctic regions (38% of total) than in temperate (24%) or tropical (21%) regions. Regional variations in these global trends also provide insights into local patterns of soil fertility and functioning. These high-resolution models provide the first steps towards representing soil ecological processes in global biogeochemical models and will enable the prediction of elemental cycling under current and future climate scenarios.

1 avan den Hoogen, Johan1 aGeisen, Stefan1 aRouth, Devin1 aFerris, Howard1 aTraunspurger, Walter1 aWardle, D1 ade Goede, Ron, G. M.1 aAdams, Byron1 aAhmad, Wasim1 aAndriuzzi, Walter, S.1 aBardgett, Richard, D.1 aBonkowski, Michael1 aCampos-Herrera, Raquel1 aCares, Juvenil, E.1 aCaruso, Tancredi1 aCaixeta, Larissa, de Brito1 aChen, Xiaoyun1 aCosta, Sofia, R.1 aCreamer, Rachel1 aCastro, José, Mauro da C1 aDam, Marie1 aDjigal, Djibril1 aEscuer, Miguel1 aGriffiths, Bryan, S.1 aGutiérrez, Carmen1 aHohberg, Karin1 aKalinkina, Daria1 aKardol, Paul1 aKergunteuil, Alan1 aKorthals, Gerard1 aKrashevska, Valentyna1 aKudrin, Alexey, A.1 aLi, Qi1 aLiang, Wenju1 aMagilton, Matthew1 aMarais, Mariette1 aMartín, José, Antonio Ro1 aMatveeva, Elizaveta1 aMayad, El, Hassan1 aMulder, Christian1 aMullin, Peter1 aNeilson, Roy1 aNguyen, T., A. Duong1 aNielsen, Uffe, N.1 aOkada, Hiroaki1 aRius, Juan, Emilio Pal1 aPan, Kaiwen1 aPeneva, Vlada1 aPellissier, Loïc1 ada Silva, Julio, Carlos Per1 aPitteloud, Camille1 aPowers, Thomas, O.1 aPowers, Kirsten1 aQuist, Casper, W.1 aRasmann, Sergio1 aMoreno, Sara, Sánchez1 aScheu, Stefan1 aSetälä, Heikki1 aSushchuk, Anna1 aTiunov, Alexei, V.1 aTrap, Jean1 avan der Putten, W1 aVestergård, Mette1 aVillenave, Cecile1 aWaeyenberge, Lieven1 aWall, Diana, H.1 aWilschut, Rutger1 aWright, Daniel, G.1 aYang, Jiue-in1 aCrowther, Thomas, Ward uhttps://www.nature.com/articles/s41586-019-1418-602534nas a2200229 4500008004100000245010900041210006900150260001200219300001600231490000800247520179600255100002102051700001702072700002402089700001502113700002302128700001902151700002402170700001902194700001702213856007402230 2018 eng d00aAeolian material transport and its role in landscape connectivity in the McMurdo Dry Valleys, Antarctica0 aAeolian material transport and its role in landscape connectivit c12/2018 a3323 - 33370 v1233 a

Arid regions, particularly polar and alpine desert environments, have diminished landscape connectivity compared to temperate regions due to limited and/or seasonal hydrological processes. For these environments, aeolian processes play a particularly important role in landscape evolution and biotic community vitality through nutrient and solute additions. The McMurdo Dry Valleys (MDV) are the largest ice-free area in Antarctica and are potentially a major source of aeolian material for the continent. From this region, samples were collected at five heights (~5, 10, 20, 50, and 100 cm) above the surface seasonally for 2013 through 2015 from Alatna Valley, Victoria Valley, Miers Valley, and Taylor Valley (Taylor Glacier, East Lake Bonney, F6 (Lake Fryxell), and Explorer’s Cove). Despite significant geological separation and varying glacial histories, low-elevation and coastal sites had similar major ion chemistries, as did high-elevation and inland locations. This locational clustering of compositions was also evident in scanning electron microscopy images and principal component analyses, particularly for samples collected at ~100 cm above the surface. Compared to published soil literature, aeolian material in Taylor Valley demonstrates a primarily down-valley transport of material toward the coast. Soluble N:P ratios in the aeolian material reflect relative nutrient enrichments seen in MDV soils and lakes, where younger, coastal soils are relatively N depleted, while older, up-valley soils are relatively P depleted. The aeolian transport of materials, including water-soluble nutrients, is an important vector of connectivity within the MDV and provides a mechanism to help “homogenize” the geochemistry of both soil and aquatic ecosystems.

1 aDiaz, Melisa, A.1 aAdams, Byron1 aWelch, Kathleen, A.1 aWelch, Sue1 aOpiyo, Stephen, O.1 aKhan, Alia, L.1 aMcKnight, Diane, M.1 aCary, Craig, S1 aLyons, Berry uhttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2017JF00458901847nas a2200193 4500008004100000022001400041245005200055210005200107260001200159300001400171490000700185520124200192100002201434700002901456700002401485700001501509700001701524856011201541 2018 eng d a0091-761300aBarium and barite dynamics in Antarctic streams0 aBarium and barite dynamics in Antarctic streams c08/2018 a811 - 8140 v463 a

Most natural waters are undersaturated with respect to barite (BaSO4), and while much work has focused on the processes of microbially mediated barite precipitation in undersaturated solutions, particularly in marine environments, little documentation exists on the changes in barite saturation in stream waters. We examined ephemeral glacial meltwater streams in the McMurdo Dry Valleys, Antarctica, that undergo large variations in streamflow and temperature on both a diel and seasonal basis. We measured dissolved Ba in stream water in downstream transects and on a diel cycle, total Ba in stream sediments, algal mats, and lake sediments. Ba concentrations decreased downstream in all four transects, and mineral saturation modeling indicates these waters go from supersaturated to undersaturated with respect to barite in very short distances. Ba is concentrated in stream benthic algal mats at a factor less than observed in marine systems. Both seasonal and diel changes in stream water temperature affect the solubility of barite near glacial sources. Our work shows that both changing stream temperature and the presence of algal materials likely play significant roles in controlling Ba concentrations in polar streams.

1 aSaelens, Elsa, D.1 aGardner, Christopher, B.1 aWelch, Kathleen, A.1 aWelch, Sue1 aLyons, Berry uhttps://pubs.geoscienceworld.org/gsa/geology/article/545184/Barium-and-barite-dynamics-in-Antarctic-streams02347nas a2200193 4500008004100000022001300041245009200054210006900146260001200215300001200227490000800239520173400247100002101981700001702002700001502019700002402034700002302058856007202081 2018 eng d a0016706100aBiogeochemical weathering of soil apatite grains in the McMurdo Dry Valleys, Antarctica0 aBiogeochemical weathering of soil apatite grains in the McMurdo  c01/2018 a136-1450 v3203 a

The biogeochemical weathering of the mineral apatite links the lithosphere to the biosphere by releasing the essential nutrient phosphorus (P) into the soil ecosystem. In Taylor Valley, Antarctica, faster rates of apatite weathering may be responsible for the higher concentrations of bioavailable soil P that exist in the Fryxell Basin as compared to the Bonney Basin. In this study, we use scanning electron microscopy to quantify the morphology and surface etching of individual apatite grains to determine whether the degree of apatite weathering differs between the Fryxell and Bonney Basins as well as saturated and dry soil sediments. We show that apatite grains from the Fryxell Basin are rounder, have fewer intact crystal faces, and are more chemically etched than grains from the Bonney Basin. In the Bonney Basin, apatite grains from dry soils show few signs of chemical dissolution, suggesting that soil moisture is a stronger control on the rate of apatite weathering in the Bonney Basin than in the Fryxell Basin. In addition, etch-pit morphologies in the Bonney Basin are more clearly controlled by the hexagonal crystal structure of apatite, while in the Fryxell Basin, etch pits demonstrate a wide range of morphologies without clear crystallographic control. Higher rates of apatite weathering in the Fryxell Basin may be due to the legacy of the physical abrasion of apatite grains during transport by a warm-based ice sheet, as well as the higher levels of precipitation and soil moisture closer to the coast. Our grain-scale approach provides a new perspective on P cycling in the McMurdo Dry Valleys and has implications for apatite weathering and P dynamics in the early stages of soil development.

1 aHeindel, Ruth, C1 aLyons, Berry1 aWelch, Sue1 aSpickard, Angela, M1 aVirginia, Ross, A. uhttps://www.sciencedirect.com/science/article/pii/S001670611732069402262nas a2200181 4500008004100000022001400041245010300055210006900158260001200227300001600239490000800255520165500263100002201918700001701940700001501957700002401972856008401996 2018 eng d a2169-895300aFe and Nutrients in Coastal Antarctic Streams: Implications for Primary Production in the Ross Sea0 aFe and Nutrients in Coastal Antarctic Streams Implications for P c12/2018 a3507 - 35220 v1233 a

The Southern Ocean (SO) has been an area of biogeochemical interest due to the presence of macronutrients (N, P, and Si) but lack of the expected primary production response, which is thought to be primarily due to Fe limitation. Because primary production is associated with increased drawdown of atmospheric CO2, it is important to quantify the fluxes of Fe and other nutrients into the SO. Here we present data from subaerial streams that flow into the Ross Sea, a sector of the coastal SO. Water samples were collected in the McMurdo Dry Valleys, Antarctica, and analyzed for macronutrients and Fe to determine the potential impact of terrestrial water input on the biogeochemistry of coastal oceanic waters. The physiochemical forms of Fe were investigated through analysis of three operationally defined forms: acid-dissolvable Fe (no filtration), filterable Fe (<0.4 μm), and dissolved Fe (<0.2 μm). The combined average flux from two McMurdo Dry Valley streams was approximately 240 moles of filterable Fe per year. The dissolved fraction of Fe made up 18%–27% of the filterable Fe. The stream data yield an average filterable stoichiometry of N3P1Si100Fe0.8, which is substantially different from the planktonic composition and suggests that these streams are a potential source of Fe and P, relative to N and Si, to coastal phytoplankton communities. While the Fe flux from these streams is orders of magnitude less than estimated eolian and iceberg sources, terrestrial streams are expected to become a more significant source of Fe to the Ross Sea in the future.

1 aOlund, Sydney, A.1 aLyons, Berry1 aWelch, Sue1 aWelch, Kathleen, A. uhttps://agupubs.pericles-prod.literatumonline.com/doi/full/10.1029/2017JG00435202094nas a2200241 4500008004100000245014400041210006900185260001200254490000600266520131100272653002001583653001401603653001701617653001501634653001501649653002401664653001301688653002201701100001701723700002201740700002401762856006601786 2018 eng d00aThe impact of fossil fuel burning related to scientific activities in the McMurdo Dry Valleys, Antarctica: Revisited0 aimpact of fossil fuel burning related to scientific activities i c04/20180 v63 a

 

Fossil fuel use associated with scienti c activities in the Taylor Valley, Antarctic has been examined to determine the fluxes of particulate organic and elemental carbon and nitrogen as well as NOx for the 2015–2016 austral summer field season. These carbon and nitrogen fluxes are compared to our previously published calculations for the 1997–1998 austral summer. In addition, we compile fossil fuel usage and resulting C and N fluxes from the major field camp in Taylor Valley, Lake Hoare Camp (LHC) from the late 1990’s through 2017. In general, the annual fluxes do vary from year to year, but there is no significant trend, at least during the primary summer field season. There is indication that increasing the length of scientific operations does increase the C and N inputs via fossil fuel burning. This works supports our original results demonstrating that over long periods of time the anthropogenic flux of N from local fossil fuel burning could become quantitatively important in the region. Although the particulate C fluxes remain very low, the recent finding of black carbon in the Taylor Valley landscape indicates more on-going monitoring of the source of this material is merited.

 

10acarbon dynamics10aemissions10afossil fuels10ahelicopter10amanagement10aMcMurdo Dry Valleys10anitrogen10ascience activites1 aLyons, Berry1 aSaelens, Elsa, D.1 aWelch, Kathleen, A. uhttps://www.elementascience.org/article/10.1525/elementa.288/04038nas a2200205 4500008004100000245015700041210006900198260001200267300001600279490000800295520333900303100001903642700002103661700002403682700001503706700002403721700001703745700002403762856004603786 2018 eng d00aNear-surface refractory black carbon observations in the atmosphere and snow in the McMurdo Dry Valleys, Antarctica and potential impacts of foehn winds0 aNearsurface refractory black carbon observations in the atmosphe c01/2018 a2877 - 28870 v1233 a

Measurements of light absorbing particles in the boundary layer of the high southern latitudes are scarce, particularly in the McMurdo Dry Valleys (MDV), Antarctica. During the 2013 - 2014 austral summer near-surface boundary layer refractory black carbon (rBC) aerosols were measured in air by a single particle soot photometer (SP2) at multiple locations in the MDV. Near-continuous rBC atmospheric measurements were collected at Lake Hoare Camp (LH) over two months and for several hours at more remote locations away from established field camps. We investigated periods dominated by both up and down-valley winds to explore the causes of differences in rBC concentrations and size distributions. Snow samples were also collected in a 1m pit on a glacier near the camp. The range of concentrations rBC in snow were 0.3 1.2 ± 0.3 μg-rBC/L-H2O, and total organic carbon were 0.3 1.4 ± 0.3 mg/L. The rBC concentrations measured in this snow pit are not sufficient to reduce surface albedo, however, there is potential for accumulation of rBC on snow and ice surfaces at low elevation throughout the MDV which were not measured as part of this study. At LH, the average background rBC mass aerosol concentrations was 1.3 ng/m3. rBC aerosol mass concentrations were slightly lower, 0.09 1.3 ng/m3, at the most remote sites in the MDV. Concentration spikes as high as 200 ng/m3 were observed at LH, associated with local activities. During a foehn wind event, the average rBC mass concentration increased to 30-50 ng m-3. Here we show the rBC increase could be due to resuspension of locally produced BC from generators, rocket toilets, and helicopters, which may remain on the soil surface until redistributed during high wind events. Quantification of local production and long-range atmospheric transport of rBC to the MDV is necessary for understanding the impacts of this species on regional climate. 

 

1 aKhan, Alia, L.1 aMcMeeking, Gavin1 aSchwarz, Joshua, P.1 aXian, Peng1 aWelch, Kathleen, A.1 aLyons, Berry1 aMcKnight, Diane, M. uhttp://doi.wiley.com/10.1002/2017JD02769602670nas a2200181 4500008004100000245011700041210006900158260001200227300001400239490000700253520207300260100002602333700001702359700002202376700002302398700002002421856004702441 2018 eng d00aObserved trends of soil fauna in the Antarctic Dry Valleys: early signs of shifts predicted under climate change0 aObserved trends of soil fauna in the Antarctic Dry Valleys early c02/2018 a312 - 3210 v993 a

Long-term observations of ecological communities are necessary for generating and testing predictions of ecosystem responses to climate change. We investigated temporal trends and spatial patterns of soil fauna along similar environmental gradients in three sites of the McMurdo Dry Valleys, Antarctica, spanning two distinct climatic phases: a decadal cool- ing trend from the early 1990s through the austral summer of February 2001, followed by a shift to the current trend of warming summers and more frequent discrete warming events. After February 2001, we observed a decline in the dominant species (the nematode Scottnema lindsayae) and increased abundance and expanded distribution of less common taxa (rotifers, tardigrades, and other nematode species). Such diverging responses have resulted in slightly greater evenness and spatial homogeneity of taxa. However, total abundance of soil fauna appears to be declining, as positive trends of the less common species so far have not compen- sated for the declining numbers of the dominant species. Interannual variation in the propor- tion of juveniles in the dominant species was consistent across sites, whereas trends in abundance varied more. Structural equation modeling supports the hypothesis that the observed biological trends arose from dissimilar responses by dominant and less common spe- cies to pulses of water availability resulting from enhanced ice melt. No direct effects of mean summer temperature were found, but there is evidence of indirect effects via its weak but signif- icant positive relationship with soil moisture. Our findings show that combining an under- standing of species responses to environmental change with long-term observations in the field can provide a context for validating and refining predictions of ecological trends in the abun- dance and diversity of soil fauna. 

1 aAndriuzzi, Walter, S.1 aAdams, Byron1 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttp://doi.wiley.com/10.1002/ecy.2090/full02241nas a2200241 4500008004100000245018900041210006900230260001200299300001600311490000700327520137700334653001501711653001801726653001301744653001701757653002001774100002801794700003201822700002301854700002601877700003301903856006301936 2018 eng d00aPhotoecology of the Antarctic cyanobacterium Leptolyngbya sp. BC1307 brought to light through community analysis, comparative genomics and in vitro photophysiology0 aPhotoecology of the Antarctic cyanobacterium iLeptolyngbyai sp B c11/2018 a5279 - 52930 v273 a

Cyanobacteria are important photoautotrophs in extreme environments such as the McMurdo Dry Valleys, Antarctica. Terrestrial Antarctic cyanobacteria experience constant darkness during the winter and constant light during the summer which influences the ability of these organisms to fix carbon over the course of an annual cycle. Here, we present a unique approach combining community structure, genomic and photophysiological analyses to understand adaptation to Antarctic light regimes in the cyanobacterium Leptolyngbya sp. BC1307. We show that Leptolyngbya sp. BC1307 belongs to a clade of cyanobacteria that inhabits near‐surface environments in the McMurdo Dry Valleys. Genomic analyses reveal that, unlike close relatives, Leptolyngbya sp. BC1307 lacks the genes necessary for production of the pigment phycoerythrin and is incapable of complimentary chromatic acclimation, while containing several genes responsible for known photoprotective pigments. Photophysiology experiments confirmed Leptolyngbya sp. BC1307 to be tolerant of short‐term exposure to high levels of photosynthetically active radiation, while sustained exposure reduced its capacity for photoprotection. As such, Leptolyngbya sp. BC1307 likely exploits low‐light microenvironments within cyanobacterial mats in the McMurdo Dry Valleys.

10aAntarctica10acyanobacteria10agenomics10aphotoecology10aphotophysiology1 aChrismas, Nathan, A. M.1 aWilliamson, Christopher, J.1 aYallop, Marian, L.1 aAnesio, Alexandre, M.1 aSánchez-Baracaldo, Patricia uhttps://onlinelibrary.wiley.com/doi/full/10.1111/mec.1495302340nas a2200181 4500008004100000022001300041245009000054210006900144260001200213490000800225520176100233100001601994700001702010700002202027700002002049700002302069856006602092 2018 eng d a0038071700aSoil biological responses to C, N and P fertilization in a polar desert of Antarctica0 aSoil biological responses to C N and P fertilization in a polar  c07/20180 v1223 a

 

In the polar desert ecosystem of the McMurdo Dry Valleys of Antarctica, biology is constrained by available liquid water, low temperatures, as well as the availability of organic matter and nutrient elements. These soil ecosystems are climate-sensitive, where projected future warming may have profound effects on biological communities and biogeochemical cycling. Warmer temperatures will mobilize meltwater from permafrost and glaciers, may increase precipitation and may be accompanied by pulses of nutrient availability. Enhanced water and nutrient availability have the potential to greatly influence desert soil biology and ecosystem processes. The objectives of this 5-year study were to determine which nutrient elements (C, N, P) are most limiting to dry valley soil communities and whether landscape history (i.e., in situ soil type and stoichiometry) influences soil community response to nutrient additions. After 3 years of no noticeable response, soil CO2 flux was significantly higher under addition of C+ N than the other treatments, regardless of in situ soil stoichiometry, but microbial biomass and invertebrate abundance were variable and not influenced in the same manner. A stable isotope incubation suggests that fertilization increases C and N mineralization from organic matter via stimulating microbial activity, with loss of both the applied treatments as well in situ C and N. However, these responses are relatively short-lived, suggesting long-term impacts on C and N cycling would only occur if meltwater and nutrient pulses are sustained over time, a scenario that is increasingly likely for the dry valleys.

 

1 aBall, Becky1 aAdams, Byron1 aBarrett, John, E.1 aWall, Diana, H.1 aVirginia, Ross, A. uhttp://linkinghub.elsevier.com/retrieve/pii/S003807171830108102240nas a2200145 4500008004100000245010800041210006900149260001200218490000800230520171900238100002101957700002501978700001702003856007402020 2018 eng d00aSoil Moisture Controls the Thermal Habitat of Active Layer Soils in the McMurdo Dry Valleys, Antarctica0 aSoil Moisture Controls the Thermal Habitat of Active Layer Soils c01/20180 v1233 a

Antarctic soil ecosystems are strongly controlled by abiotic habitat variables. Regional climate change in the McMurdo Dry Valleys is expected to cause warming over the next century, leading to an increase in frequency of freeze-thaw cycling in the soil habitat. Previous studies show that physiological stress associated with freeze-thaw cycling adversely affects invertebrate populations by decreasing abundance and positively selecting for larger body sizes. However, it remains unclear whether or not climate warming will indeed enhance the frequency of annual freeze-thaw cycling and associated physiological stresses. This research quantifies the frequency, rate, and spatial heterogeneity of active layer freezing to better understand how regional climate change may affect active layer soil thermodynamics, and, in turn, affect soil macroinvertebrate communities. Shallow active layer temperature, specific conductance, and soil moisture were observed along natural wetness gradients. Field observations show that the frequency and rate of freeze events are nonlinearly related to freezable soil moisture (θf). Over a 2 year period, soils at θf < 0.080 m3/m3 experienced between 15 and 35 freeze events and froze rapidly compared to soils with θf > 0.080 m3/m3, which experienced between 2 and 6 freeze events and froze more gradually. A numerical soil thermodynamic model is able to simulate observed freezing rates across a range of θf, reinforcing a well-known causal relationship between soil moisture and active layer freezing dynamics. Findings show that slight increases in soil moisture can potentially offset the effect of climate warming on exacerbating soil freeze-thaw cycling.

1 aWlostowski, Adam1 aGooseff, Michael, N.1 aAdams, Byron uhttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JG00401802513nas a2200277 4500008004100000245010700041210006900148260001200217300001600229490000700245520169000252653001201942653001601954653001601970653001401986653001502000653001602015100002602031700002102057700002402078700001702102700001702119700002002136700002402156856005502180 2018 eng d00aSpatial and temporal patterns of microbial mats and associated invertebrates along an Antarctic stream0 aSpatial and temporal patterns of microbial mats and associated i c10/2018 a1911–19210 v413 a

 

Microbial biofilms are biological hotspots in many alpine and polar ecosystems, but the controls on and functional significance of their fauna are little known. We studied cyanobacterial mats and the underlying sediment in a glacial meltwater stream in the McMurdo Dry Valleys, Antarctica. We investigated mat biomass (total and phototrophic), diatoms, and micro-meiofauna (nematodes, rotifers, and tardigrades) at nine sites along a 1670 m stream reach in a cold, low-flow growing season, and in a warmer growing season in which peak flows (above 100 L s−1) scoured the mats. Diatom and invertebrate communities were not related, but mat biomass in the low-flow year was negatively related to nematode abundance, including that of the omnivore Eudorylaimus. In the high-flow year that followed, invertebrate abundance was reduced in the mats, diatom community structure was altered, and mat biomass was higher. The difference in invertebrate abundance between years was greater in mats in upstream reaches, where the greatest increases in flow velocity may have occurred, and was negligible in mats in downstream reaches as well as in the sediment beneath the mats. Integrating our results with previous findings, we generate two predictive hypotheses to be tested in glacial meltwater streams: (1) under peak flows invertebrates decline in the microbial mats, while (2) the sediment beneath the mats is a refuge from the flow disturbance. Our results also suggest that, under stable flow conditions, microinvertebrate grazers could exert top-down control on microbial mat biomass.

 

10adiatoms10aDisturbance10aDry valleys10aEpilithon10aMicrofauna10aStream flow1 aAndriuzzi, Walter, S.1 aStanish, Lee, F.1 aSimmons, Breana, L.1 aJaros, Chris1 aAdams, Byron1 aWall, Diana, H.1 aMcKnight, Diane, M. uhttp://link.springer.com/10.1007/s00300-018-2331-402332nas a2200193 4500008004100000245017900041210006900220260001200289300001600301490000700317520164300324100001701967700001701984700002202001700001702023700002302040700002002063856005502083 2018 eng d00aStable C and N isotope ratios reveal soil food web structure and identify the nematode Eudorylaimus antarcticus as an omnivore–predator in Taylor Valley, Antarctica0 aStable C and N isotope ratios reveal soil food web structure and c05/2018 a1013–10180 v413 a

Soil food webs of the McMurdo Dry Valleys, Antarctica are simple. These include primary trophic levels of mosses, algae, cyanobacteria, bacteria, archaea, and fungi, and their protozoan and metazoan consumers (including relatively few species of nematodes, tardigrades, rotifers, and microarthropods). These biota are patchily distributed across the landscape, with greatest faunal biodiversity associated with wet soil. Understanding trophic structure is critical to studies of biotic interactions and distribution; yet, McMurdo Dry Valley soil food web structure has been inferred from limited laboratory culturing and micro- scopic observations. To address this, we measured stable isotope natural abundance ratios of C (13C/12C) and N (15N/14N) for di erent metazoan taxa (using whole body biomass) to determine soil food web structure in Taylor Valley, Antarctica. Nitrogen isotopes were most useful in di erentiating trophic levels because they fractionated predictably at higher trophic levels. Using 15N/14N, we found that three trophic levels were present in wet soil habitats. While cyanobacterial mats were the primary trophic level, the nematode Plectus murrayi, tardigrade Acutuncus antarcticus, and rotifers composed a secondary trophic level of grazers. Eudorylaimus antarcticus had a 15N/14N ratio that was 2–4‰ higher than that of grazers, indicating that this species is the sole member of a tertiary trophic level. Understanding the trophic positions of soil fauna is critical to predictions of current and future species interactions and their distributions for the McMurdo Dry Valleys, Antarctica.

1 aShaw, Ashley1 aAdams, Byron1 aBarrett, John, E.1 aLyons, Berry1 aVirginia, Ross, A.1 aWall, Diana, H. uhttp://link.springer.com/10.1007/s00300-017-2243-802975nas a2200289 4500008004100000245013500041210006900176260001200245490000600257520199400263653002902257653002302286653002402309653003102333653002602364653002602390100002602416700002402442700001602466700002002482700002202502700002602524700002502550700002302575700001702598856007002615 2018 eng d00aStoichiometric Shifts in Soil C:N:P Promote Bacterial Taxa Dominance, Maintain Biodiversity, and Deconstruct Community Assemblages0 aStoichiometric Shifts in Soil CNP Promote Bacterial Taxa Dominan c07/20180 v93 a

Imbalances in C:N:P supply ratios may cause bacterial resource limitations and constrain biogeochemical processes, but the importance of shifts in soil stoichiometry are complicated by the nearly limitless interactions between an immensely rich species pool and a multiple chemical resource forms. To more clearly identify the impact of soil C:N:P on bacteria, we evaluated the cumulative effects of single and coupled long-term nutrient additions (i.e., C as mannitol, N as equal concentrations NH4 + and NO3 − , and P as Na3PO4) and water on communities in an Antarctic polar desert, Taylor Valley. Untreated soils possessed relatively low bacterial diversity, simplified organic C sources due to the absence of plants, limited inorganic N, and excess soil P potentially attenuating links between C:N:P. After 6 years of adding resources, an alleviation of C and N colimitation allowed one rare Micrococcaceae, an Arthrobacter species, to dominate, comprising 47% of the total community abundance and elevating soil respiration by 136% relative to untreated soils. The addition of N alone reduced C:N ratios, elevated bacterial richness and diversity, and allowed rare taxa relying on ammonium and nitrite for metabolism to become more abundant [e.g., nitrite oxidizing Nitrospira species (Nitrosomonadaceae), denitrifiers utilizing nitrite (Gemmatimonadaceae) and members of Rhodobacteraceae with a high affinity for ammonium]. Based on community co-occurrence networks, lower C:P ratios in soils following P and CP additions created more diffuse and less connected communities by disrupting 73% of species interactions and selecting for taxa potentially exploiting abundant P. Unlike amended nutrients, water additions alone elicited no lasting impact on communities. Our results suggest that as soils become nutrient rich a wide array of outcomes are possible from species dominance and the deconstruction of species interconnectedness to the maintenance of biodiversity.

10aecological stoichiometry10aLake Fryxell Basin10aMcMurdo Dry Valleys10anetwork community modeling10anutrient colimitation10aSolirubrobacteriaceae1 aAanderud, Zachary, T.1 aSaurey, Sabrina, D.1 aBall, Becky1 aWall, Diana, H.1 aBarrett, John, E.1 aMuscarella, Mario, E.1 aGriffin, Natasha, A.1 aVirginia, Ross, A.1 aAdams, Byron uhttps://www.frontiersin.org/article/10.3389/fmicb.2018.01401/full01835nas a2200169 4500008004100000245013700041210006900178260001200247300001800259490000700277520122000284100002101504700002501525700002401550700001701574856007401591 2018 eng d00aTransit times and rapid chemical equilibrium explain chemostasis in glacial meltwater streams in the McMurdo Dry Valleys, Antarctica0 aTransit times and rapid chemical equilibrium explain chemostasis c12/2018 a13322 - 133310 v453 a

Fluid  transit  time  is  understood  to  be  an  important  control  on  the  shape  of concentration-discharge (C-q) relationships, yet empirical evidence supporting this linkage is limited. We investigated C-q relationships for weathering-derived solutes across seven Antarctic glacial meltwate streams. We hypothesized that (H1) solute fluxes in McMurdo Dry Valley streams are reaction limited so that C-q relationships are characterized by dilution and that (H2) transit time explains between-stream variability in the degree of C-q dilution. Results show that C-q relationships are chemostatic because solute equilibrium times are shorter than stream corridor fluid transit times. Between-stream variability in the efficiency of solute production is positively correlated with transit time, suggesting that transit time is an important control on the solute export regime. These results provide empirical evidence for the controls on weathering-derived C-q relationships and have important implications for Antarctic ecosystems and solute export regimes of watersheds worldwide.

1 aWlostowski, Adam1 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aLyons, Berry uhttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL08036907387nas a2200145 4500008004100000245013200041210006900173260003000242300000800272490001000280520680100290100001707091700002007108856011307128 2018 eng d00aTrophic relationships in soil communities how abiotic stress affects biotic interactions in the McMurdo Dry Valleys, Antarctica0 aTrophic relationships in soil communities how abiotic stress aff bColorado State University a1190 vPh.D.3 a

Understanding of the distribution and complexity of soil food webs and their role in ecosystem processes is limited. This is partially due to the difficulty studying the enormous diversity of species in belowground ecosystems and identifying the many roles of this diversity in ecosystem processes. Despite this, there is strong interest in understanding how the soil food web contributes to ecosystem processes such as decomposition, nutrient cycling, and carbon cycling. Yet, before we can fully understand how soil food webs are linked to ecosystem processes, more information is needed on their complex trophic interactions and how soil food webs respond to changing environmental variables. The McMurdo Dry Valleys in Antarctica provide an excellent opportunity to study soil communities and their trophic interactions because of soil food web simplicity and limited ecological interactions that are not easily distinguished in more diverse systems. However, it is unknown whether trophic interactions actually play a role in structuring soil communities in this ecosystem and whether these interactions are affected by environmental factors. The aim of this dissertation is to disentangle those questions.

In the first chapter of this dissertation, I give the background for my research. I introduce the challenges for studying soil biodiversity and its food web structure. Next, I discuss the usefulness of the McMurdo Dry Valleys as a simple, model system for researching trophic interactions in soil. The details of the current understanding of the McMurdo Dry Valley soil food web are demonstrated and I have highlighted gaps in this knowledge. In the second chapter of this dissertation, I address the question: What trophic interactions are present in the McMurdo Dry Valley soils? Here, I sought to elucidate the soil food web structure using stable isotopes (particularly 15N) and I present isotopic signatures for soil fauna taxa for one location in Taylor Valley, Antarctica. The natural abundance of 13C and 15N were measured for soil fauna and microbial mats sampled in both wet and dry soils near Von Guerard stream. This study revealed that three trophic levels were present in wet soils at this location and two trophic levels were present in dry soil. This is the first isotopic confirmation of Eudorylaimus antarcticus (Nematoda) as an omnivore-predator (in wet soil habitat), and challenges long-held assumptions of trophic simplicity of the McMurdo Dry Valley region.

Building on the findings of Chapter 2, Chapter 3 seeks to expand the understanding of dry valley food webs and the role of trophic interactions in structuring communities under environmental change. Specifically, I address the question: How do environmental variables (soil salinity and moisture) affect dry valley soil taxa and their trophic interactions? I show the results of a laboratory microcosm experiment on how elevated salinity and moisture affect four soil communities. Using soil collected from Taylor Valley, Antarctica, bacteria, bacteria with Scottnema lindsayae, bacteria with E. antarcticus, and bacteria with both S. lindsayae and E. antarcticus were established in microcosms under control or high salinity treatments and control or high moisture treatments (full factorial design). The results of this experiment showed that S. lindsayae has top down effects on bacterial abundance under control salinity but these top down effects were alleviated under high salinity. This study is the first to empirically show that biological interactions structure dry valley soil communities.

The fourth chapter follows the conclusions of Chapters 2 and 3, and seeks to determine food web structure and trophic interactions at the landscape scale in the McMurdo Dry Valleys. I sampled soil from 160 sites across 8 valleys ranging from the coast to high elevation near the polar plateau to address the question: How does the soil food web and its organic carbon sources vary across the McMurdo Dry Valley landscape with distance from coast and elevation? These valleys represent a temperature and moisture gradient, which affects ecosystem primary productivity. This study revealed that food web structure varies by habitat – the most diverse and complex trophic interactions exist in wet habitat near the coast where resources are more abundant. However, in dry habitat, where organic carbon resources are scarce, up to two trophic levels exist. These results build off of Chapter 2, and show that E. antarcticus can occupy either a predator trophic position when resources are high (wet soil) or a primary consumer position when resources are low (dry soil). Since climate-driven increases in hydrological connectivity are expected to alter soil moisture and resources, the distribution and abundance of soil biodiversity and their biotic interactions in formerly dry soil habitats may ultimately shift.

In Chapter 5, I asked if the lessons learned about soil food webs in the McMurdo Dry Valleys apply to a more complex ecosystem? In this study, I used soil nematode communities from the Loch Vale Watershed (Rocky Mountain National Park, Colorado) to test whether long-term nitrogen addition affected soil food web structure and function. Results from this study indicated that a faster-cycling, bacterial food web was prevalent in N-addition plots, as evidenced by abundance of r-selected bacterivore nematodes. Previously, lower bacterial abundance and soil carbon were found in the N-addition plots (compared to control) and the results presented in this dissertation suggest that these changes are likely trophic. Along with Chapter 3, the evidence that I present here support the hypothesis for top-down effects of microbivore nematodes on bacteria, which is consistent in subalpine and Antarctic soils.

In summary, through both field and laboratory experiments, my PhD project has: 1) defined the soil food web structure of the McMurdo Dry Valleys using stable isotopes; 2) revealed how top down interactions affect bacteria populations and how elevated stress (e.g. soil salinity) relieves the top down pressure; 3) showed how the soil food web structure varies across the landscape of the McMurdo Dry Valleys, Antarctica as related to soil C sources; and 4) shown how nitrogen addition affects soil food web dynamics in Colorado sub-alpine soil nematode community (Loch Vale Watershed, LVWS, Rocky Mountain National Park). These results have informed our understanding of soil communities and their trophic relationships in polar and subalpine ecosystems.

1 aShaw, Ashley1 aWall, Diana, H. uhttp://search.proquest.com/openview/0d494a3f115b75da1c7a2464e341808f/1?pq-origsite=gscholar&cbl=18750&diss=y02937nas a2200157 4500008004100000245006000041210006000101260001200161300001400173490000700187520246500194100001702659700001402676700002402690856006502714 2017 eng d00aCa isotopic geochemistry of an Antarctic aquatic system0 aCa isotopic geochemistry of an Antarctic aquatic system c01/2017 a882 - 8910 v443 a

The McMurdo Dry Valleys, Antarctica, are a polar desert ecosystem. The hydrologic system of the dry valleys is linked to climate with ephemeral streams that flow from glacial melt during the austral summer. Past climate variations have strongly influenced the closed-basin, chemically stratified lakes on the valley floor. Results of previous work point to important roles for both in-stream processes (e.g., mineral weathering, precipitation and dissolution of salts) and in-lake processes (e.g., mixing with paleo-seawater and calcite precipitation) in determining the geochemistry of these lakes. These processes have a significant influence on calcium (Ca) biogeochemistry in this aquatic ecosystem, and thus variations in Ca stable isotope compositions of the waters can aid in validating the importance of these processes. We have analyzed the Ca stable isotope compositions of streams and lakes in the McMurdo Dry Valleys. The results validate the important roles of weathering of aluminosilicate minerals and/or CaCO3 in the hyporheic zone of the streams, and mixing of lake surface water with paleo-seawater and precipitation of Ca-salts during cryo-concentration events to form the deep lake waters. The lakes in the McMurdo Dry Valleys evolved following different geochemical pathways, evidenced by their unique, nonsystematic Ca isotope signatures. 

1 aLyons, Berry1 aBullen, T1 aWelch, Kathleen, A. uhttp://onlinelibrary.wiley.com/doi/10.1002/2016GL071169/full02723nas a2200229 4500008004100000245015600041210006900197260001200266300001600278490000700294520192000301100002202221700002102243700002402264700002002288700002502308700001702333700002402350700002902374700002502403856006502428 2017 eng d00aCharacterizing hyporheic exchange processes using high-frequency electrical conductivity-discharge relationships on subhourly to interannual timescales0 aCharacterizing hyporheic exchange processes using highfrequency  c05/2017 a4124 - 41410 v533 a

Concentration-discharge (C-Q) relationships are often used to quantify source water contributions and biogeochemical processes occurring within catchments, especially during discrete hydrological events. Yet, the interpretation of C-Q hysteresis is often confounded by complexity of the critical zone, such as numerous source waters and hydrochemical nonstationarity. Consequently, researchers must often ignore important runoff pathways and geochemical sources/sinks, especially the hyporheic zone because it lacks a distinct hydrochemical signature. Such simplifications limit efforts to identify processes responsible for the transience of C-Q hysteresis over time. To address these limitations, we leverage the hydrologic simplicity and long-term, high-frequency Q and electrical conductivity (EC) data from streams in the McMurdo Dry Valleys, Antarctica. In this two end-member system, EC can serve as a proxy for the concentration of solutes derived from the hyporheic zone. We utilize a novel approach to decompose loops into subhysteretic EC-Q dynamics to identify individual mechanisms governing hysteresis across a wide range of timescales. We find that hydrologic and hydraulic processes govern EC response to diel and seasonal Q variability and that the effects of hyporheic mixing processes on C-Q transience differ in short and long streams. We also observe that variable hyporheic turnover rates govern EC-Q patterns at daily to interannual timescales. Last, subhysteretic analysis reveals a period of interannual freshening of glacial meltwater streams related to the effects of unsteady flow on hyporheic exchange. The subhysteretic analysis framework we introduce may be applied more broadly to constrain the processes controlling C-Q transience and advance understanding of catchment evolution. 

1 aSingley, Joel, G.1 aWlostowski, Adam1 aBergstrom, Anna, J.1 aSokol, Eric, R.1 aTorrens, Christa, L.1 aJaros, Chris1 aWilson, Colleen, E.1 aHendrickson, Patrick, J.1 aGooseff, Michael, N. uhttp://onlinelibrary.wiley.com/doi/10.1002/2016WR019739/full00851nas a2200265 4500008004100000245009100041210006900132260001200201300001400213490000600227100002500233700002200258700001700280700002100297700002400318700001700342700002400359700002100383700002000404700003300424700003100457700002300488700002000511856005400531 2017 eng d00aDecadal ecosystem response to an anomalous melt season in a polar desert in Antarctica0 aDecadal ecosystem response to an anomalous melt season in a pola c09/2017 a1334-13380 v11 aGooseff, Michael, N.1 aBarrett, John, E.1 aAdams, Byron1 aDoran, Peter, T.1 aFountain, Andrew, G1 aLyons, Berry1 aMcKnight, Diane, M.1 aPriscu, John, C.1 aSokol, Eric, R.1 aTakacs-Vesbach, Cristina, D.1 aVandegehuchte, Martijn, L.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://www.nature.com/articles/s41559-017-0253-001830nas a2200193 4500008004100000245014200041210006900183260001200252300001400264490000700278520115100285100001801436700002601454700002401480700003301504700001701537700002001554856006201574 2017 eng d00aDecoupled responses of soil bacteria and their invertebrate consumer to warming, but not freeze-thaw cycles, in the Antarctic Dry Valleys0 aDecoupled responses of soil bacteria and their invertebrate cons c10/2017 a1242-12490 v203 a

Altered temperature profiles resulting in increased warming and freeze–thaw cycle (FTC) frequency pose great ecological challenges to organisms in alpine and polar ecosystems. We performed a laboratory microcosm experiment to investigate how temperature variability affects soil bacterial cell numbers, and abundance and traits of soil microfauna (the microbivorous nematode Scottnema lindsayae) from McMurdo Dry Valleys, Antarctica. FTCs and constant freezing shifted nematode body size distribution towards large individuals, driven by higher mortality among smaller individuals. FTCs reduced both bacterial and nematode abundance, but bacterial cell numbers also declined under warming, demonstrating decoupled consumer–prey responses. We predict that higher occurrence of FTCs in cold ecosystems will select for large body size within soil microinvertebrates and overall reduce their abundance. In contrast, warm temperatures without FTCs could lead to divergent responses in soil bacteria and their microinvertebrate consumers, potentially affecting energy and nutrient transfer rates in soil food webs of cold ecosystems.

1 aKnox, Matthew1 aAndriuzzi, Walter, S.1 aBuelow, Heather, N.1 aTakacs-Vesbach, Cristina, D.1 aAdams, Byron1 aWall, Diana, H. uhttp://onlinelibrary.wiley.com/doi/10.1111/ele.12819/full03366nas a2200205 4500008004100000245009200041210006900133260001200202300001400214490000700228520274200235100001902977700001802996700001903014700001503033700001903048700002303067700002403090856004603114 2017 eng d00aDissolved black carbon in the global cryosphere: Concentrations and chemical signatures0 aDissolved black carbon in the global cryosphere Concentrations a c06/2017 a6226-62340 v443 a

Black carbon (BC) is derived from the incomplete combustion of biomass and fossil fuels and can enhance glacial recession when deposited on snow and ice surfaces. Here we explore the influence of environmental conditions and the proximity to anthropogenic sources on the concentration and composition of dissolved black carbon (DBC), as measured by benzenepolycaroxylic acid (BPCA) markers, across snow, lakes, and streams from the global cryosphere. Data are presented from Antarctica, the Arctic, and high alpine regions of the Himalayas, Rockies, Andes, and Alps. DBC concentrations spanned from 0.62 μg/L to 170 μg/L. The median and (2.5, 97.5) quantiles in the pristine samples were 1.8 μg/L (0.62, 12), and nonpristine samples were 21 μg/L (1.6, 170). DBC is susceptible to photodegradation when exposed to solar radiation. This process leads to a less condensed BPCA signature. In general, DBC across the data set was composed of less polycondensed DBC. However, DBC from the Greenland Ice Sheet (GRIS) had a highly condensed BPCA molecular signature. This could be due to recent deposition of BC from Canadian wildfires. Variation in DBC appears to be driven by a combination of photochemical processing and the source combustion conditions under which the DBC was formed. Overall, DBC was found to persist across the global cryosphere in both pristine and nonpristine snow and surface waters. The high concentration of DBC measured in supraglacial melt on the GRIS suggests that DBC can be mobilized across ice surfaces. This is significant because these processes may jointly exacerbate surface albedo reduction in the cryosphere. 

1 aKhan, Alia, L.1 aWagner, Sasha1 aJaffé, Rudolf1 aXian, Peng1 aWilliams, Mark1 aArmstrong, Richard1 aMcKnight, Diane, M. uhttp://doi.wiley.com/10.1002/2017GL07348502077nas a2200181 4500008004100000245016100041210006900202260001200271490000600283520140000289100002601689700002601715700003301741700002001774700002101794700002501815856005501840 2017 eng d00aEarly diverging lineages within Cryptomycota and Chytridiomycota dominate the fungal communities in ice-covered lakes of the McMurdo Dry Valleys, Antarctica0 aEarly diverging lineages within Cryptomycota and Chytridiomycota c11/20170 v73 a

Antarctic ice-covered lakes are exceptional sites for studying the ecology of aquatic fungi under conditions of minimal human disturbance. In this study, we explored the diversity and community composition of fungi in five permanently covered lake basins located in the Taylor and Miers Valleys of Antarctica. Based on analysis of the 18S rRNA sequences, we showed that fungal taxa represented between 0.93% and 60.32% of the eukaryotic sequences. Cryptomycota and Chytridiomycota dominated the fungal communities in all lakes; however, members of Ascomycota, Basidiomycota, Zygomycota, and Blastocladiomycota were also present. Of the 1313 fungal OTUs identified, the two most abundant, belonging to LKM11 and Chytridiaceae, comprised 74% of the sequences. Significant differences in the community structure were determined among lakes, water depths, habitat features (i.e., brackish vs. freshwaters), and nucleic acids (DNA vs. RNA), suggesting niche differentiation. Network analysis suggested the existence of strong relationships among specific fungal phylotypes as well as between fungi and other eukaryotes. This study sheds light on the biology and ecology of basal fungi in aquatic systems. To our knowledge, this is the first report showing the predominance of early diverging lineages of fungi in pristine limnetic ecosystems, particularly of the enigmatic phylum Cryptomycota.

1 aRojas-Jimenez, Keilor1 aWurzbacher, Christian1 aBourne, Elizabeth, Charlotte1 aChiuchiolo, Amy1 aPriscu, John, C.1 aGrossart, Hans-Peter uhttps://www.nature.com/articles/s41598-017-15598-w02751nas a2200181 4500008004100000022001300041245010100054210006900155260001200224300001200236490000800248520216000256100002502416700002102441700002402462700001702486856006602503 2017 eng d a0169555X00aHydrologic connectivity and implications for ecosystem processes - Lessons from naked watersheds0 aHydrologic connectivity and implications for ecosystem processes c01/2017 a63 - 710 v2773 a

Hydrologic connectivity has received great attention recently as our conceptual models of watersheds and water quality have evolved in the past several decades. However, the structural complexity of most temperate watersheds (i.e. connections among shallow soils, deep aquifers, the atmosphere and streams) and the dynamic seasonal changes that occur within them (i.e., plant senescence which impacts evapotranspiration) create significant challenges to characterizing or quantifying hydrologic connectivity. The McMurdo Dry Valleys, a polar desert in Antarctica, provide a unique opportunity to study hydrologic connectivity because there is no vegetative cover (and therefore no transpiration), and no deep aquifers connected to surface soils or streams. Glacier melt provides stream flow to well-established channels and closed-basin, ice-covered lakes on the valley floor. Streams are also connected to shallow hyporheic zones along their lengths, which are bounded at ~75 cm depth by ice-cemented permafrost. These hydrologic features and connections provide water for and underpin biological communities. Hence, exchange of water among them provides a vector for exchange of energy and dissolved solutes. Connectivity is dynamic on timescales of a day to a flow season (6–12 weeks), as streamflow varies over these timescales. The timescales over which these connections occur is also dynamic. Exchanges between streams and hyporheic zones, for example, have been estimated to be as short as hours to as long as several weeks. These exchanges have significant implications for the biogeochemistry of these systems and the biotic communities in each feature. Here we evaluate the lessons we can learn about hydrologic connectivity in the MDV watersheds that are simplified in the context of processes occurring and water reservoirs included in the landscape, yet are sensitive to climate controls and contain substantial physical heterogeneity. We specifically explore several metrics that are simple and/or commonly employed in hydrologic analyses and interpret them in the context of connectivity between and among hydrologic features.

1 aGooseff, Michael, N.1 aWlostowski, Adam1 aMcKnight, Diane, M.1 aJaros, Chris uhttp://linkinghub.elsevier.com/retrieve/pii/S0169555X1630248302884nas a2200133 4500008004100000245012700041210006900168260004800237490001000285520235800295100002102653700002502674856005102699 2017 eng d00aHydrologic connectivity in the McMurdo Dry Valleys, Antarctica: Water-mediated mass and energy fluxes in streams and soils0 aHydrologic connectivity in the McMurdo Dry Valleys Antarctica Wa aBoulder, CObUniversity of Colorado Boulder0 vPh.D.3 a

Chapter 1 synthesizes 20 years of stream gauge observations (discharge, water temperature, and specific conductance) to assess patterns of hydrologic connectivity between glaciers, streams and lakes. Results reveal hydrologic patterns across daily, annual and inter-annual timescales, which together characterize the hydrologic regime of MDV streams. Also, stream gauge data display a relationship between stream length and hydrologic regime. Longer streams are more intermittent, warmer, and saltier than shorter streams. This work provides physical context for understanding biological differences among MDV streams, while providing a methodological template for quantifying hydrologic connectivity.

Chapter 2 investigates the nature of concentration-discharge relationships for weathering-derived solutes in MDV streams. The relative simplicity of MDV “watersheds” permits the use of concentration-discharge relationships to infer hydrologic and chemical mixing dynamics occurring along the river corridor. Long-term stream geochemical data show that weathering derived solutes exhibit chemostatic C-Q relationships. Chemostasis implies that rates of solute production and/or mobilization scale proportionately with stream discharge. A numerical weathering and solute transport model suggests that chemostasis is maintained by a positive relationship between weathering rate and discharge along the stream corridor.

Finally, Chapters 3 and 4 investigate water-mediated energy fluxes within the soil habitat. Nematode communities in MDV are highly sensitive to the thermodynamic regime of active layer soils. Soil moisture and air temperature data were collected across natural wetness gradients adjacent to fluvial features to assess the control of soil moisture on the soil thermal regime. Observations show that wetter soils freeze less frequently and more gradually than drier soils. Also, a numerical soil heat transfer model suggests that increases in soil moisture and air temperature result in warmer average habitat temperature, an extension of the duration of time the soil habitat spends above freezing, and a reduction in the rate and frequency of freezing. The results of this chapter provide a physical context for understanding current and future patterns of ecosystem structure and function in MDV soils.

1 aWlostowski, Adam1 aGooseff, Michael, N. uhttps://scholar.colorado.edu/cven_gradetds/77/00637nas a2200157 4500008004100000245015300041210007000194260001200264300001200276490000700288100002200295700002100317700002100338700002700359856009300386 2017 eng d00aThe influence of föhn winds on Glacial Lake Washburn and palaeotemperatures in the McMurdo Dry Valleys, Antarctica, during the Last Glacial Maximum0 ainfluence of föhn winds on Glacial Lake Washburn and palaeotempe c10/2017 a457-4670 v291 aObryk, Maciek, K.1 aDoran, Peter, T.1 aWaddington, E.D.1 aMcKay, Christopher, P. uhttps://www.cambridge.org/core/product/identifier/S0954102017000062/type/journal_article03797nas a2200157 4500008004100000245012100041210007100162260001200233300001600245490000700261520325100268100001703519700002403536700001703560856006203577 2017 eng d00aA temporal stable isotopic (δ18O, δD, d-excess) comparison in glacier meltwater streams, Taylor Valley, Antarctica0 atemporal stable isotopic δ18O δD dexcess comparison in glacier m c08/2017 a3069 - 30830 v313 a

In this paper, we describe the importance of hyporheic dynamics within Andersen Creek and Von Guerard Stream, Taylor Valley, Antarctica, from the 20102011 melt season using natural tracers. Water collection started at flow onset and continued, with weekly hyporheiczone sampling. The water δ18O and δD values were isotopically lighter in the beginning and heavier later in the season. Dexcess measurements were used as an indicator of mixing because an evaporative signature was evident and distinguishable between 2 primary endmembers (glacier meltwater and hyporheic zone). Hyporheiczone influence on the channel water was variable with a strong control on streamwater chemistry, except at highest discharges. This work supports previous research indicating that Von Guerard Stream has a large, widespread hyporheic zone that varies in size with time and discharge. Andersen Creek, with a smaller hyporheic zone, displayed hyporheiczone solute interaction through the influence from subsurface hypersaline flow. Overall, the evolution of Taylor Valley hyporheiczone hydrology is described seasonally. In midDecember, the hyporheic zone is a dynamic system exchanging with the glacier meltwater in the channel, and with diminishing flow in January, the hyporheic zone drains back into the channel flow also impacting stream chemistry. This work adds new information on the role of hyporheic zonestream interaction in these glacier meltwater streams. 

1 aLeslie, D.L.1 aWelch, Kathleen, A.1 aLyons, Berry uhttp://onlinelibrary.wiley.com/doi/10.1002/hyp.11245/full01407nas a2200445 4500008004100000245007700041210006900118260001200187490005900199100002200258700002400280700001900304700002100323700002100344700001900365700002400384700002000408700001700428700002400445700001700469700002300486700001900509700002100528700002000549700002100569700002200590700002300612700002500635700001800660700002200678700002300700700002300723700002500746700001800771700002000789700002400809700002600833700002500859856007700884 2016 eng d00aAerobiology Over Antarctica – A New Initiative for Atmospheric Ecology0 aAerobiology Over Antarctica A New Initiative for Atmospheric Eco c02/20160 v7767961946103149272350113651344451428464791101239365741 aPearce, David, A.1 aAlekhina, Irina, A.1 aTerauds, Aleks1 aWilmotte, Annick1 aQuesada, Antonio1 aEdwards, Arwyn1 aDommergue, Aurelien1 aSattler, Birgit1 aAdams, Byron1 aMagalhaes, Catarina1 aChu, Wan-Loy1 aLau, Maggie, C. Y.1 aCary, Craig, S1 aSmith, David, J.1 aWall, Diana, H.1 aEguren, Gabriela1 aMatcher, Gwynneth1 aBradley, James, A.1 ade Vera, Jean-Pierre1 aElster, Josef1 aHughes, Kevin, A.1 aCuthbertson, Lewis1 aBenning, Liane, G.1 aGunde-Cimerman, Nina1 aConvey, Peter1 aHong, Soon, Gyu1 aPointing, Steve, B.1 aPellizari, Vivian, H.1 aVincent, Warwick, F. uhttp://journal.frontiersin.org/Article/10.3389/fmicb.2016.00016/abstract00939nas 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.html00694nas a2200205 4500008004100000022001400041245012500055210006900180260001600249300001400265490000700279100002000286700001800306700002300324700001900347700002000366700001700386700002300403856006200426 2016 eng d a0831-279600aGenetic diversity among populations of Antarctic springtails (Collembola) within the Mackay Glacier ecotone 10 aGenetic diversity among populations of Antarctic springtails Col cJan-09-2016 a762 - 7700 v591 aBeet, Clare, R.1 aHogg, Ian, D.1 aCollins, Gemma, E.1 aCowan, Don, A.1 aWall, Diana, H.1 aAdams, Byron1 aWilson, John-James uhttp://www.nrcresearchpress.com/doi/10.1139/gen-2015-019400658nas a2200193 4500008004100000022001400041245011300055210007100168260001200239300001400251490000700265100001800272700002000290700002300310700003100333700001900364700001700383856006400400 2016 eng d a0722-406000aImpact of diurnal freeze–thaw cycles on the soil nematode Scottnema lindsayae in Taylor Valley, Antarctica0 aImpact of diurnal freeze–thaw cycles on the soil nematode Scottn c04/2016 a583 - 5920 v391 aKnox, Matthew1 aWall, Diana, H.1 aVirginia, Ross, A.1 aVandegehuchte, Martijn, L.1 aSan Gil, Inigo1 aAdams, Byron uhttps://link.springer.com/article/10.1007/s00300-015-1809-600676nas a2200181 4500008004100000245012900041210006900170260001200239490000600251100002400257700002000281700002400301700002200325700002500347700002100372700003300393856006800426 2016 eng d00aMicrobial Community Responses to Increased Water and Organic Matter in the Arid Soils of the McMurdo Dry Valleys, Antarctica0 aMicrobial Community Responses to Increased Water and Organic Mat c07/20160 v71 aBuelow, Heather, N.1 aWinter, Ara, S.1 aVan Horn, David, J.1 aBarrett, John, E.1 aGooseff, Michael, N.1 aSchwartz, Egbert1 aTakacs-Vesbach, Cristina, D. uhttp://journal.frontiersin.org/article/10.3389/fmicb.2016.0104002591nas a2200193 4500008004100000245013100041210006900172260001200241300001100253490000700264520191200271100002202183700002402205700002402229700003302253700002402286700001702310856007002327 2016 eng d00aNutrient treatments alter microbial mat colonization in two glacial meltwater streams from the McMurdo Dry Valleys, Antarctica0 aNutrient treatments alter microbial mat colonization in two glac c03/2016 afiw0490 v923 a

Microbial mats are abundant in many alpine and polar aquatic ecosystems. With warmer temperatures, new hydrologic pathways are developing in these regions and increasing dissolved nutrient fluxes. In the McMurdo Dry Valleys, thermokarsting may release both nutrients and sediment, and has the potential to influence mats in glacial meltwater streams. To test the role of nutrient inputs on community structure, we created nutrient diffusing substrata (NDS) with agar enriched in N, P and N + P, with controls, and deployed them into two Dry Valley streams. We found N amendments (N and N + P) to have greater chlorophyll-a concentrations, total algal biovolume, more fine filamentous cyanobacteria and a higher proportion of live diatoms than other treatments. Furthermore, N treatments were substantially elevated in Bacteroidetes and the small diatom, Fistulifera pelliculosa. On the other hand, species richness was almost double in P and N + P treatments over others, and coccoid green algae and Proteobacteria were more abundant in both streams. Collectively, these data suggest that nutrients have the potential to stimulate growth and alter community structure in glacial meltwater stream microbial mats, and the recent erosion of permafrost and accelerated glacial melt will likely impact resident biota in polar lotic systems here and elsewhere.

1 aKohler, Tyler, J.1 aVan Horn, David, J.1 aDarling, Joshua, P.1 aTakacs-Vesbach, Cristina, D.1 aMcKnight, Diane, M.1 aWagner, Dirk uhttp://femsec.oxfordjournals.org/lookup/doi/10.1093/femsec/fiw04902226nas a2200229 4500008004100000245011100041210006900152260001200221300001100233490000700244520146700251100002401718700002201742700002301764700001901787700002201806700002401828700002101852700002001873700003301893856007001926 2016 eng d00aPatterns of bacterial biodiversity in the glacial meltwater streams of the McMurdo Dry Valleys, Antarctica0 aPatterns of bacterial biodiversity in the glacial meltwater stre c08/2016 afiw1480 v923 a

Microbial consortia dominate glacial meltwater streams from polar regions, including the McMurdo Dry Valleys (MDV), where they thrive under physiologically stressful conditions. In this study, we examined microbial mat types and sediments found in 12 hydrologically diverse streams to describe the community diversity and composition within and across sites. Sequencing of the 16S rRNA gene from 129 samples revealed ∼24 000 operational taxonomic units (<97% DNA similarity), making streams the most biodiverse habitat in the MDV. Principal coordinate analyses revealed significant but weak clustering by mat type across all streams (ANOSIM R-statistic = 0.28) but stronger clustering within streams (ANOSIM R-statistic from 0.28 to 0.94). Significant relationships (P < 0.05) were found between bacterial diversity and mat ash-free dry mass, suggesting that diversity is related to the hydrologic regimes of the various streams, which are predictive of mat biomass. However, correlations between stream chemistry and community members were weak, possibly reflecting the importance of internal processes and hydrologic conditions. Collectively, these results suggest that localized conditions dictate bacterial community composition of the same mat types and sediments from different streams, and while MDV streams are hotspots of biodiversity in an otherwise depauperate landscape, controls on community structure are complex and site specific.

1 aVan Horn, David, J.1 aWolf, Caitlin, R.1 aColman, Daniel, R.1 aJiang, Xiaoben1 aKohler, Tyler, J.1 aMcKnight, Diane, M.1 aStanish, Lee, F.1 aYazzie, Terrill1 aTakacs-Vesbach, Cristina, D. uhttp://femsec.oxfordjournals.org/lookup/doi/10.1093/femsec/fiw14802242nas a2200181 4500008004100000245012300041210006900164260001200233300001400245490000700259520163300266100002101899700002501920700002401945700001701969700001701986856005702003 2016 eng d00aPatterns of hydrologic connectivity in the McMurdo dry valleys, Antarctica: a synthesis of 20 years of hydrologic data0 aPatterns of hydrologic connectivity in the McMurdo dry valleys A c04/2016 a2958-29750 v303 a

Streams in the McMurdo Dry Valleys (MDVs) of Antarctica moderate an important hydrologic and biogeochemical connection between upland alpine glaciers, valley-bottom soils, and lowland closed-basin lakes. Moreover, MDV streams are simple but dynamic systems ideal for studying interacting hydrologic and ecological dynamics. This work synthesizes 20 years of hydrologic data, collected as part of the MDVs Long-Term Ecological Research project, to assess spatial and temporal dynamics of hydrologic connectivity between glaciers, streams, and lakes. Long-term records of stream discharge (Q), specific electrical conductance (EC), and water temperature (T) from 18 streams were analysed in order to quantify the magnitude, duration, and frequency of hydrologic connections over daily, annual, and inter-annual timescales. At a daily timescale, we observe predictable diurnal variations in Q, EC, and T. At an annual timescale, we observe longer streams to be more intermittent, warmer, and have higher median EC values, compared to shorter streams. Longer streams also behave chemostatically with respect to EC, whereas shorter streams are more strongly characterized by dilution. Inter-annually, we observe significant variability in annual runoff volumes, likely because of climatic variability over the 20 record years considered. Hydrologic connections at all timescales are vital to stream ecosystem structure and function. This synthesis of hydrologic connectivity in the MDVs provides a useful end-member template for assessing hydrologic connectivity in more structurally complex temperate watersheds. 

1 aWlostowski, Adam1 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aJaros, Chris1 aLyons, Berry uhttp://onlinelibrary.wiley.com/doi/10.1002/hyp.1081801836nas a2200193 4500008004100000245013000041210006900171260001200240300001600252490000700268520116600275100002501441700002401466700002001490700002401510700002401534700001701558856006701575 2016 eng d00aStream biogeochemical and suspended sediment responses to permafrost degradation in stream banks in Taylor Valley, Antarctica0 aStream biogeochemical and suspended sediment responses to permaf c03/2016 a1723 - 17320 v133 a

 Stream channels in the McMurdo Dry Valleys are characteristically wide, incised, and stable. At typical flows, streams occupy a fraction of the oversized channels, providing habitat for algal mats. In January 2012, we discovered substantial channel erosion and subsurface thermomechanical erosion undercutting banks of the Crescent Stream. We sampled stream water along the impacted reach and compared concentrations of solutes to the long-term data from this stream ( ∼  20 years of monitoring). Thermokarst-impacted stream water demonstrated higher electrical conductivity, and concentrations of chloride, sulfate, sodium, and nitrate than the long-term medians. These results suggest that this mode of lateral permafrost degradation may substantially impact stream solute loads and potentially fertilize stream and lake ecosystems. The potential for sediment to scour or bury stream algal mats is yet to be determined, though it may offset impacts of associated increased nutrient loads to streams.

1 aGooseff, Michael, N.1 aVan Horn, David, J.1 aSudman, Zachary1 aMcKnight, Diane, M.1 aWelch, Kathleen, A.1 aLyons, Berry uhttp://www.biogeosciences.net/13/1723/2016/bg-13-1723-2016.pdf03321nas a2200205 4500008004100000022001400041245008600055210006900141260001200210300001600222490000700238520262100245100001702866700002302883700002402906700002502930700001502955700002402970856012102994 2015 eng d a0091-761300aAntarctic streams as a potential source of iron for the Southern Ocean: Figure 1.0 aAntarctic streams as a potential source of iron for the Southern c11/2016 a1003 - 10060 v433 a

Due to iron’s role in oceanic primary production, there has been great interest in quantifying the importance of Fe in regions where concentrations are very low and macronutrients, nitrate and phosphate, are available. Measurements of filterable (i.e., <0.4 μm) Fe concentrations in streams from Taylor Valley, McMurdo Dry Valleys, Antarctica, suggest that coastal-zone stream Fe input to the Southern Ocean could potentially play an important role in primary production in nearshore regions. Filterable Fe (fFe) data from streams in the McMurdo Dry Valleys were used to represent glacier meltwater that flows through ice-free landscape with the potential of transporting Fe to the Antarctic coastal zone. Estimates of potential fFe flux to the Antarctic Peninsula region using our mean fFe concentration of 10.6 µg L–1 combined with an estimate of ice-free area for the Antarctic Peninsula result in an fFe flux of 1.2 × 107 g yr–1. Although small compared to iceberg and aeolian Fe fluxes, future stream input to the Southern Ocean could increase due to glacier retreat and 

1 aLyons, Berry1 aDailey, Kelsey, R.1 aWelch, Kathleen, A.1 aDeuerling, Kelly, M.1 aWelch, Sue1 aMcKnight, Diane, M. uhttp://geology.gsapubs.org/lookup/doi/10.1130/G36989.1http://geology.geoscienceworld.org/lookup/doi/10.1130/G36989.108594nas a2200241 4500008004100000022001300041245020300054210006900257260001200326300001400338490000800352520755800360100001907918700002407937700002007961700002407981700002308005700002308028700001708051700002708068700002708095856023008122 2015 eng d a0009254100aComparison of arsenic and molybdenum geochemistry in meromictic lakes of the McMurdo Dry Valleys, Antarctica: Implications for oxyanion-forming trace element behavior in permanently stratified lakes0 aComparison of arsenic and molybdenum geochemistry in meromictic  c05/2015 a110 - 1250 v4043 a

Water samples were collected for arsenic (As) and molybdenum (Mo) analysis from different depths in Lakes Hoare and Fryxell, both of which are located in the Taylor Valley within the McMurdo Dry Valleys of Antarctica. Sampling depths within each lake were chosen to capture variations in As and Mo concentrations and As speciation in the oxic mixolimnia and anoxic monimolimnia of these meromictic lakes. Arsenic concentrations ranged from 0.67 nmol kg− 1 to 3.54 nmol kg− 1 in Lake Hoare and from 1.69 nmol kg− 1 to 17.5 nmol kg− 1 in Lake Fryxell. Molybdenum concentrations varied between 5.05 nmol kg− 1 and 43 nmol kg− 1 in Lake Hoare, and between 3.52 nmol kg− 1 and 25.5 nmol kg− 1 in Lake Fryxell. Concentrations of As and Mo generally increased with depth in the mixolimnion of each lake, consistent with uptake near the ice–water interface by organic particles and/or Fe/Mn oxides/oxyhydroxides, followed by gravitational settling and regeneration/remineralization at depth in the vicinity of the redoxcline. Arsenic concentrations either remained constant (Hoare) or increased with depth (Fryxell) in the anoxic monimolimnia, whereas Mo exhibited dramatic decreases in concentrations across the redoxcline in both lakes. Geochemical modeling predicts that As and Mo occur as thioanions in the anoxic bottom waters of Lakes Hoare and Fryxell, and further that the contrasting behavior of both trace elements reflects the respective reactivity of their thioanions towards Fe-sulfide minerals such as mackinawite (FeS) and/or pyrite (FeS2). More specifically, the geochemical model suggests that Fe-sulfide mineral precipitation in the anoxic monimolimnia of both lakes regulates dissolved sulfide concentrations at levels that are too low for As-sulfide minerals (e.g., orpiment, realgar) to precipitate, whereas mackinawite and/or pyrite react(s) with particle reactive thiomolybdate anions, possibly forming an Fe–Mo–S mineral that precipitates and, hence, leads to Mo removal from solution.

1 aYang, Ningfang1 aWelch, Kathleen, A.1 aMohajerin, Jade1 aTelfeyan, Katherine1 aChevis, Darren, A.1 aGrimm, Deborah, A.1 aLyons, Berry1 aWhite, Christopher, D.1 aJohannesson, Karen, H. uhttp://linkinghub.elsevier.com/retrieve/pii/S0009254115001874http://api.elsevier.com/content/article/PII:S0009254115001874?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0009254115001874?httpAccept=text/plain01522nas 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_S095410201400047906572nas a2200169 4500008004100000245008400041210006900125520601300194100001906207700002406226700001506250700001906265700001706284700002106301700002406322856005606346 2015 eng d00aPatterns and processes of salt efflorescences in the McMurdo region, Antarctica0 aPatterns and processes of salt efflorescences in the McMurdo reg3 a

Evaporite salts are abundant around the McMurdo region, Antarctica (~78°S) due to very low precipitation, low relative humidity, and limited overland flow. Hygroscopic salts in the McMurdo Dry Valleys (MDVs) are preferentially formed in locations where liquid water is present in the austral summer, including along ephemeral streams, ice-covered lake boundaries, or shallow groundwater tracks. In this study, we collected salts from the Miers, Garwood, and Taylor Valleys on the Antarctic continent, as well as around McMurdo Station on Ross Island in close proximity to water sources with the goal of understanding salt geochemistry in relationship to the hydrology of the area. Halite is ubiquitous; sodium is the major cation (ranging from 70%–90% of cations by meq kg−1 sediment) and chloride is the major anion (>50%) in nearly all samples. However, a wide variety of salt phases and morphologies are tentatively identified through scanning electron microscopy (SEM) and X-ray diffraction (XRD) work. We present new data that identifies trona (Na3(CO3)(HCO3)·2H2O), tentative gaylussite (Na2Ca(CO3)2·5H2O), and tentative glauberite (Na2Ca(SO4)2) in the MDV, of which the later one has not been documented previously. Our work allows for the evaluation of processes that influence brine evolution on a local scale, consequently informing assumptions underlying large-scale processes (such as paleoclimate) in the MDV. Hydrological modeling conducted in FREZCHEM and PHREEQC suggests that a model based on aerosol deposition alone in low elevations on the valley floor inadequately characterizes salt distributions found on the surfaces of the soil because it does not account for other hydrologic inputs/outputs. Implications for the salt distributions include their use as tracers for paleolake levels, geochemical tracers of ephemeral water tracks or “wet patches” in the soil, indicators of chemical weathering products, and potential delineators of ecological communities.

1 aBisson, K., M.1 aWelch, Kathleen, A.1 aWelch, Sue1 aSheets, J., M.1 aLyons, Berry1 aLevy, Joseph, S.1 aFountain, Andrew, G uhttp://aaarjournal.org/doi/abs/10.1657/AAAR0014-02400864nas a2200217 4500008004100000245020400041210006900245260001200314300001600326490000700342100002400349700001600373700002400389700002500413700001700438700001300455700001700468700002100485700002100506856011900527 2015 eng d00aPotential for real-time understanding of coupled hydrologic and biogeochemical processes in stream ecosystems: Future integration of telemetered data with process models for glacial meltwater streams0 aPotential for realtime understanding of coupled hydrologic and b c08/2015 a6725 - 67380 v511 aMcKnight, Diane, M.1 aCozzetto, K1 aCullis, James, D.S.1 aGooseff, Michael, N.1 aJaros, Chris1 aKoch, J.1 aLyons, Berry1 aNeupauer, R., M.1 aWlostowski, Adam uhttp://doi.wiley.com/10.1002/2015WR017618http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015WR01761802527nas a2200181 4500008004100000245016700041210006900208260001200277300001600289490000700305520184500312100002102157700002402178700002402202700002102226700001702247856008102264 2015 eng d00aPressure-driven, shoreline currents in a perennially ice-covered, pro-glacial lake in Antarctica, identified from a LiCl tracer injected into a pro-glacial stream0 aPressuredriven shoreline currents in a perennially icecovered pr c05-2015 a2212 - 22310 v293 a

The distribution of streamwater within ice-covered lakes influences sub-ice currents, biological activity and shoreline morphology. Perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica, provide an excellent natural laboratory to study hydrologic–limnologic interactions under ice cover. For a 2 h period on 17 December 2012, we injected a lithium chloride tracer into Andersen Creek, a pro-glacial stream flowing into Lake Hoare. Over 4 h, we collected 182 water samples from five stream sites and 15 ice boreholes. Geochemical data showed that interflow travelled West of the stream mouth along the shoreline and did not flow towards the lake interior. The chemistry of water from Andersen Creek was similar to the chemistry of water below shoreline ice. Additional evidence for Westward flow included the morphology of channels on the ice surface, the orientation of ripple marks in lake sediments at the stream mouth and equivalent temperatures between Andersen Creek and water below shoreline ice. Streamwater deflected to the right of the mouth of the stream, in the opposite direction predicted by the Coriolis force. Deflection of interflow was probably caused by the diurnal addition of glacial runoff and stream discharge to the Eastern edge of the lake, which created a strong pressure gradient sloping to the West. This flow directed stream momentum away from the lake interior, minimizing the impact of stream momentum on sub-ice currents. It also transported dissolved nutrients and suspended sediments to the shoreline region instead of the lake interior, potentially affecting biological productivity and bedform development.

1 aCastendyk, Devin1 aMcKnight, Diane, M.1 aWelch, Kathleen, A.1 aNiebuhr, Spencer1 aJaros, Chris uhttp://doi.wiley.com/10.1002/hyp.v29.9http://doi.wiley.com/10.1002/hyp.1035204908nas a2200193 4500008004100000022001300041245008800054210006900142260001600211300001200227490000700239520413400246100002304380700002204403700002004425700001804445700002104463856023004484 2015 eng d a0883292700aReconstructing the evolution of Lake Bonney, Antarctica using dissolved noble gases0 aReconstructing the evolution of Lake Bonney Antarctica using dis cJan-07-2015 a46 - 610 v583 a

Lake Bonney (LB), located in Taylor valley, Antarctica, is a perennially ice-covered lake with two lobes, West Lake Bonney (WLB) and East Lake Bonney (ELB), which are separated by a narrow ridge. Numerous studies have attempted to reconstruct the evolution of LB because of its sensitivity to climatic variations and the lack of reliable millennial-scale continental records of climate in this region of Antarctica. However, these studies are limited by the availability of accurate lacustrine chronologies. Here, we attempt to better constrain the chronology of LB and thus, the evolution of past regional climate by estimating water residence times based on He, Ne and Ar concentrations and isotopic ratios in both WLB and ELB.

3He and 4He excesses up to two and three orders of magnitude and 35–150 times the atmospheric values are observed for WLB and ELB samples, respectively. In comparison, while measured 40Ar/36Ar ratios are atmospheric (∼295.5) in ELB, WLB samples display 40Ar/36Ar ratios of up to ∼315 reflecting addition of radiogenic 40Ar. Both4He and 40Ar excesses clearly identify the addition of subglacial discharge (SGD) from underneath Taylor Glacier into WLB at depths of 25 m and 35 m. He isotopic ratios suggest that He excesses are predominantly crustal (>93%) in origin with small mantle contributions (<7%). These crustal 4He and 40Ar excesses are used together with basement rock production rates of these isotopes to derive first-order approximations of water residence times for both lobes. Numerous factors capable of affecting water residence times are evaluated and corrected 4He and 40Ar water ages are used to place further constrains into the reconstruction of both WLB and ELB history. Combined 4He and 40Ar ages in WLB suggest maximum water residence times of ∼250 kyrs BP. These results support the presence of remnant water from proglacial lakes that existed during Marine Isotope Stage 7 (160–240 kyrs) in WLB, in agreement with previous studies. In comparison, 4He ages in ELB are much younger (<27 kyrs BP) and display a complex evolutionary history that is very different from WLB. 4He ages also suggest that the ELB ice cover formed significantly earlier (∼1.5 kyrs BP) than previously reported. The timing of these hydrologic changes in ELB appears to correspond to regional and global climatic events that are recorded in both the Taylor Dome ice-core record as well as in other Dry Valley Lakes.

1 aWarrier, Rohit, B.1 aCastro, Clara, M.1 aHall, Chris, M.1 aKenig, Fabien1 aDoran, Peter, T. uhttp://linkinghub.elsevier.com/retrieve/pii/S088329271500044Xhttp://api.elsevier.com/content/article/PII:S088329271500044X?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S088329271500044X?httpAccept=text/plain04591nas a2201033 4500008004100000022001400041245009100055210006900146260001600215300001100231490000700242520199300249100002002242700002202262700001802284700001602302700002002318700001502338700001802353700001502371700001802386700001702404700001602421700001402437700001402451700001702465700001802482700002102500700001602521700001102537700001502548700002002563700001902583700001602602700001802618700001602636700001402652700001602666700001502682700001602697700001602713700001602729700001802745700001602763700001602779700001302795700001802808700001202826700001402838700001402852700001402866700001602880700001402896700001402910700002002924700001102944700001702955700001502972700002502987700001603012700001703028700001703045700001503062700001703077700001403094700001403108700001703122700001803139700001603157700002403173700002303197700001603220700001503236700001603251700001803267700001803285700001803303700001803321700001503339700001803354700002003372700001603392700001503408700001803423700001703441700001303458700002103471856006503492 2015 eng d a0954-102000aA roadmap for Antarctic and Southern Ocean science for the next two decades and beyond0 aroadmap for Antarctic and Southern Ocean science for the next tw cJan-02-2015 a3 - 180 v273 a

Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to ‘scan the horizon’ to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consultation was a fundamental principle for the development of a collective, international view of the most important future directions in Antarctic science. From the many possibilities, the horizon scan identified 80 key scientific questions through structured debate, discussion, revision and voting. Questions were clustered into seven topics: i) Antarctic atmosphere and global connections, ii) Southern Ocean and sea ice in a warming world, iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond, and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require innovative experimental designs, novel applications of technology, invention of next-generation field and laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples. Sustained year-round access to Antarctica and the Southern Ocean will be essential to increase winter-time measurements. Improved models are needed that represent Antarctica and the Southern Ocean in the Earth System, and provide predictions at spatial and temporal resolutions useful for decision making. A co-ordinated portfolio of cross-disciplinary science, based on new models of international collaboration, will be essential as no scientist, programme or nation can realize these aspirations alone

1 aKennicutt, M.C.1 aChown, Steven, L.1 aCassano, J.J.1 aLiggett, D.1 aPeck, Lloyd, S.1 aMassom, R.1 aRintoul, S.R.1 aStorey, J.1 aVaughan, D.G.1 aWilson, T.J.1 aAllison, I.1 aAyton, J.1 aBadhe, R.1 aBaeseman, J.1 aBarrett, P.J.1 aBell, Elanor, R.1 aBertler, N.1 aBo, S.1 aBrandt, A.1 aBromwich, David1 aCary, Craig, S1 aClark, M.S.1 aConvey, Peter1 aCosta, E.S.1 aCowan, D.1 aDeconto, R.1 aDunbar, R.1 aElfring, C.1 aEscutia, C.1 aFrancis, J.1 aFricker, H.A.1 aFukuchi, M.1 aGilbert, N.1 aGutt, J.1 aHavermans, C.1 aHik, D.1 aHosie, G.1 aJones, C.1 aKim, Y.D.1 aLe Maho, Y.1 aLee, S.H.1 aLeppe, M.1 aLeitchenkov, G.1 aLi, X.1 aLipenkov, V.1 aLochte, K.1 aLópez-Martínez, J.1 aüdecke, C.1 aLyons, Berry1 aMarenssi, S.1 aMiller, H.1 aMorozova, P.1 aNaish, T.1 aNayak, S.1 aRavindra, R.1 aRetamales, J.1 aRicci, C.A.1 aRogan-Finnemore, M.1 aRopert-Coudert, Y.1 aSamah, A.A.1 aSanson, L.1 aScambos, T.1 aSchloss, I.R.1 aShiraishi, K.1 aSiegert, M.J.1 aSimões, J.C.1 aStorey, B.1 aSparrow, M.D.1 aWall, Diana, H.1 aWalsh, J.C.1 aWilson, G.1 aWinther, J.G.1 aXavier, J.C.1 aYang, H.1 aSutherland, W.J. uhttp://www.journals.cambridge.org/abstract_S095410201400067400392nas a2200133 4500008004100000022001400041245003900055210003900094260001200133100002000145700002200165700001500187856005600202 2015 eng d a0028-083600aSoil biodiversity and human health0 aSoil biodiversity and human health c11/20151 aWall, Diana, H.1 aNielsen, Uffe, N.1 aSix, Johan uhttp://www.nature.com/doifinder/10.1038/nature1574402755nas a2200169 4500008004100000020002200041245005500063210005300118260005100171300001200222520220300234100001902437700001802456700002202474700002002496856006902516 2014 eng d a978-3-642-45212-300aAntarctic Terrestrial Microbiology : Invertebrates0 aAntarctic Terrestrial Microbiology Invertebrates aBerlin, HeidelbergbSpringer Berlin Heidelberg a55 - 783 a

Terrestrial invertebrates are the largest permanent residents for much of the Antarctic continent with body lengths < 2 mm for most. The fauna consists of the arthropod taxa Collembola (springtails) and Acari (mites) as well as the microinvertebrates Nematoda, Tardigrada and Rotifera. Diversity in continental Antarctica is lower compared with warmer regions such as the Antarctic Peninsula and the subantarctic islands and several taxa such as the arthropods have considerably restricted distributions. The highest diversity of invertebrates is found along the Transantarctic Mountains of the Ross Sea Region and taxa are likely to be relicts from a warmer past that have survived in glacial refugia. Dispersal among the extremely fragmented Antarctic landscape is likely to be limited to transport via fresh- or salt-waters, particularly for the arthropod taxa, although long-distance wind dispersal is also possible for the microinvertebrates. Invertebrates possess several adaptations to low moisture levels and extreme cold temperatures in Antarctica. For example, nematodes and tardigrades avoid extreme dry and cold temperatures by entering a desiccation-resistant anhydrobiotic state. In contrast, arthropods do not have such a resistant state and freezing is lethal. Adaptations for the arthropod taxa include freeze avoidance and the production of intracellular, antifreeze proteins. Climate changes in Antarctica are likely to pose significant challenges for the invertebrate fauna. Changes in temperature, soil moisture and associated shifts in taxon distributions as well as the potential for non-indigenous species introductions are all likely to have considerable impacts on the Antarctic fauna. From a conservation perspective, there is a pressing need for terrestrial observation networks to record the present state of Antarctic terrestrial ecosystems as well as to monitor impending changes. Biosecurity measures which minimize species introductions or transfers of organisms within Antarctica will be essential.

1 aCowan, Don, A.1 aHogg, Ian, D.1 aStevens, Mark, I.1 aWall, Diana, H. uhttp://link.springer.com/content/pdf/10.1007/978-3-642-45213-0_402177nas a2200217 4500008004100000022001300041245014200054210006900196260001600265300001100281490000700292520131900299100002201618700002201640700002401662700002101686700002101707700003301728700002101761856017701782 2014 eng d a0025332400aAutonomous Year-Round Sampling and Sensing to Explore the Physical and Biological Habitability of Permanently Ice-Covered Antarctic Lakes0 aAutonomous YearRound Sampling and Sensing to Explore the Physica cJan-09-2014 a8 - 170 v483 a

The lakes of the McMurdo Dry Valleys, Antarctica, are some of the only systems on our planet that are perennially ice-covered and support year-round metabolism. As such, these ecosystems can provide important information on conditions and life in polar regions on Earth and on other icy worlds in our solar system. Working in these extreme environments of the Dry Valleys poses many challenges, particularly with respect to data collection during dark winter months when logistical constraints make fieldwork difficult. In this paper, we describe the motivation, design, and challenges for this recently deployed instrumentation in Lake Bonney, a lake that has been the subject of summer research efforts for more than 40 years. The instrumentation deployed includes autonomous water, phytoplankton, and sediment samplers as well as cable-mounted profiling platforms with dissolved gas and fluorometry sensors. Data obtained from these instruments will allow us, for the first time, to define the habitability of this environment during the polar night. We include lessons learned during deployment and recommendations for effective instrument operation in these extreme conditions.

1 aWinslow, Luke, A.1 aDugan, Hilary, A.1 aBuelow, Heather, N.1 aCronin, Kyle, D.1 aPriscu, John, C.1 aTakacs-Vesbach, Cristina, D.1 aDoran, Peter, T. uhttp://openurl.ingenta.com/content/xref?genre=article&issn=0025-3324&volume=48&issue=5&spage=8http://www.ingentaconnect.com/content/mts/mtsj/2014/00000048/00000005/art0000204850nas a2200217 4500008004100000022001300041245007600054210006900130260001200199300001400211490000800225520403500233100001704268700001704285700002204302700001904324700001404343700002404357700002104381856023004402 2014 eng d a0009254100aBoron isotopic geochemistry of the McMurdo Dry Valley lakes, Antarctica0 aBoron isotopic geochemistry of the McMurdo Dry Valley lakes Anta c10/2014 a152 - 1640 v3863 a

 

The geochemistry of boron was investigated in the ice-covered lakes and glacier meltwater streams within Taylor and Wright Valley of the McMurdo Dry Valleys (MCM), Antarctica, in order to achieve a greater understanding of the source of boron to these aquatic systems and how in-lake processes control boron concentration. Selected lake depths (surface and bottom water) and streams were analyzed for boron geochemistry. Boron stable isotope values in these waters span the range of + 12.3‰ to + 51.4‰, which corresponds to the variations from glacier meltwater streams to the hypolimnion of a highly evaporated hypersaline lake. The data demonstrate that the major sources of B to the aquatic system are via terrestrial chemical weathering of aluminosilicates within the stream channels, and a marine source, either currently being introduced by marine-derived aerosols or in the form of ancient seawater. Lakes Fryxell, Hoare, and upper waters of Lake Joyce, which experience more terrestrial influence of aluminosilicate chemical weathering via glacial meltwater streams, display a mixture of these two major sources, while the source of B in the bottom waters of Lake Joyce appears to be primarily of marine origin. Lakes Bonney and Vanda and the Blood Falls brine have a marine-like source whose δ11B values have become more positive by mineral precipitation and/or adsorption. Don Juan Pond displays a terrestrial aluminosilicate influence of a marine-like source. These hypersaline lake waters from Antarctica are similar in δ11B to other hypersaline lake waters globally, suggesting that similar processes control their B geochemistry.

 

 

1 aLeslie, D.L.1 aLyons, Berry1 aWarner, Nathaniel1 aVengosh, Avner1 aOlesik, J1 aWelch, Kathleen, A.1 aDeuerling, Kelly uhttp://linkinghub.elsevier.com/retrieve/pii/S000925411400391Xhttp://api.elsevier.com/content/article/PII:S000925411400391X?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S000925411400391X?httpAccept=text/plain00571nas a2200181 4500008004100000022001400041245008700055210006900142260001200211300001200223490000800235100001700243700002000260700002300280700001600303700001800319856005200337 2014 eng d a1313-298900aEcological Biogeography of the Terrestrial Nematodes of Victoria Land, Antarctica0 aEcological Biogeography of the Terrestrial Nematodes of Victoria c06/2015 a29 - 710 v4191 aAdams, Byron1 aWall, Diana, H.1 aVirginia, Ross, A.1 aBroos, Emma1 aKnox, Matthew uhttp://zookeys.pensoft.net/articles.php?id=389901873nas a2200241 4500008004100000022001400041245005200055210005100107260001200158300001400170490000700184520122300191100001401414700001501428700002001443700002101463700001501484700001401499700001601513700002001529700001501549856006701564 2014 eng d a1084-545300aForum: Climate Change and Environmental History0 aForum Climate Change and Environmental History c04/2014 a281 - 3640 v193 a

This Forum explores global climate change, one of this century's most prominent environmental issues. Authors answer two critical questions: (1) How does the study of climate history enrich the field of environmental history more broadly? (2) How can environmental historians contribute to present-day understandings of and responses to global climate change? This introductory essay (and the Forum more generally) contribute to both environmental history research and climate change discussions by grappling with several key issues including the agency of nonhuman nature and environmental determinism, environmental governance, climate as a cultural construction, the history of environmental ideas and discourse, environmental narratives, the commodification of nature, and the politicization of the natural and life sciences. This essay also shows how the study of climate history provides methodological and practical tools for environmental historians. It analyzes the role of interdisciplinary sources and archives, scale, the place of science in environmental history scholarship, and the relevance of environmental histories for present-day policymaking and public discussions about climate change.

1 aCarey, M.1 aGarone, P.1 aHowkins, Adrian1 aEndfield, G., H.1 aCulver, L.1 aWhite, S.1 aJohnson, S.1 aFleming, J., R.1 aGarone, P. uhttp://envhis.oxfordjournals.org/cgi/doi/10.1093/envhis/emu00400633nas a2200193 4500008004100000245011600041210006900157260001200226300001400238490000700252100002200259700001800281700002000299700001400319700002600333700001600359700002100375856004300396 2014 eng d00aGlobal-scale patterns of assemblage structure of soil nematodes in relation to climate and ecosystem properties0 aGlobalscale patterns of assemblage structure of soil nematodes i c01/2014 a968 - 9780 v231 aNielsen, Uffe, N.1 aAyres, Edward1 aWall, Diana, H.1 aLi, Grace1 aBardgett, Richard, D.1 aWu, Tiehang1 aGarey, James, R. uhttp://doi.wiley.com/10.1111/geb.1217702909nas a2200193 4500008004100000245012700041210006900168260001200237300001600249490000700265520221300272100002502485700002002510700002302530700002502553700002402578700002202602856009102624 2014 eng d00aSoil animal responses to moisture availability are largely scale, not ecosystem dependent: insight from a cross-site study0 aSoil animal responses to moisture availability are largely scale c08/2014 a2631 - 26430 v203 a

Climate change will result in reduced soil water availability in much of the world either due to changes in precipitation or increased temperature and evapotranspiration. How communities of mites and nematodes may respond to changes in moisture availability is not well known, yet these organisms play important roles in decomposition and nutrient cycling processes. We determined how communities of these organisms respond to changes in moisture availability and whether common patterns occur along fine-scale gradients of soil moisture within four individual ecosystem types (mesic, xeric and arid grasslands and a polar desert) located in the western United States and Antarctica, as well as across a cross-ecosystem moisture gradient (CEMG) of all four ecosystems considered together. An elevation transect of three sampling plots was monitored within each ecosystem and soil samples were collected from these plots and from existing experimental precipitation manipulations within each ecosystem once in fall of 2009 and three times each in 2010 and 2011. Mites and nematodes were sorted to trophic groups and analyzed to determine community responses to changes in soil moisture availability. We found that while both mites and nematodes increased with available soil moisture across the CEMG, within individual ecosystems, increases in soil moisture resulted in decreases to nematode communities at all but the arid grassland ecosystem; mites showed no responses at any ecosystem. In addition, we found changes in proportional abundances of mite and nematode trophic groups as soil moisture increased within individual ecosystems, which may result in shifts within soil food webs with important consequences for ecosystem functioning. We suggest that communities of soil animals at local scales may respond predictably to changes in moisture availability regardless of ecosystem type but that additional factors, such as climate variability, vegetation composition, and soil properties may influence this relationship over larger scales.

1 aSylvain, Zachary, A.1 aWall, Diana, H.1 aCherwin, Karie, L.1 aPeters, Debra, P. C.1 aReichmann, Lara, G.1 aSala, Osvaldo, E. uhttp://doi.wiley.com/10.1111/gcb.2014.20.issue-8http://doi.wiley.com/10.1111/gcb.1252203560nas a2200397 4500008004100000022001400041245005200055210004800107260001200155300001400167490000700181520243500188100001802623700002202641700001902663700002502682700001902707700002002726700002202746700002102768700002402789700002102813700002302834700002702857700002302884700002802907700001702935700001902952700002202971700002002993700002103013700002503034700002603059700002003085856005703105 2014 eng d a0012-961500aThe spatial structure of Antarctic biodiversity0 aspatial structure of Antarctic biodiversity c05/2014 a203 - 2440 v843 a

Patterns of environmental spatial structure lie at the heart of the most fundamental and familiar patterns of diversity on Earth. Antarctica contains some of the strongest environmental gradients on the planet and therefore provides an ideal study ground to test hypotheses on the relevance of environmental variability for biodiversity. To answer the pivotal question, “How does spatial variation in physical and biological environmental properties across the Antarctic drive biodiversity?” we have synthesized current knowledge on environmental variability across terrestrial, freshwater, and marine Antarctic biomes and related this to the observed biotic patterns. The most important physical driver of Antarctic terrestrial communities is the availability of liquid water, itself driven by solar irradiance intensity. Patterns of biota distribution are further strongly influenced by the historical development of any given location or region, and by geographical barriers. In freshwater ecosystems, free water is also crucial, with further important influences from salinity, nutrient availability, oxygenation, and characteristics of ice cover and extent. In the marine biome there does not appear to be one major driving force, with the exception of the oceanographic boundary of the Polar Front. At smaller spatial scales, ice cover, ice scour, and salinity gradients are clearly important determinants of diversity at habitat and community level. Stochastic and extreme events remain an important driving force in all environments, particularly in the context of local extinction and colonization or recolonization, as well as that of temporal environmental variability. Our synthesis demonstrates that the Antarctic continent and surrounding oceans provide an ideal study ground to develop new biogeographical models, including life history and physiological traits, and to address questions regarding biological responses to environmental variability and change.

 

1 aConvey, Peter1 aChown, Steven, L.1 aClarke, Andrew1 aBarnes, David, K. A.1 aBokhorst, Stef1 aCummings, Vonda1 aDucklow, Hugh, W.1 aFrati, Francesco1 aGreen, T., G. Allan1 aGordon, Shulamit1 aGriffiths, Huw, J.1 aHoward-Williams, Clive1 aHuiskes, Ad, H. L.1 aLaybourn-Parry, Johanna1 aLyons, Berry1 aMcMinn, Andrew1 aMorley, Simon, A.1 aPeck, Lloyd, S.1 aQuesada, Antonio1 aRobinson, Sharon, A.1 aSchiaparelli, Stefano1 aWall, Diana, H. uhttp://www.esajournals.org/doi/abs/10.1890/12-2216.102923nas a2200229 4500008004100000245012800041210006900169260001200238490000600250520215100256100001602407700002602423700002002449700002402469700002202493700001802515700002402533700001702557700002302574700001902597856007702616 2014 eng d00aSpring thaw ionic pulses boost nutrient availability and microbial growth in entombed Antarctic Dry Valley cryoconite holes0 aSpring thaw ionic pulses boost nutrient availability and microbi c12/20140 v53 a

The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of spring thaw toward fully melted holes. The cryoconite holes had a mean isolation age from the glacial drainage system of 3.4 years, with an increasing mass of aqueous nutrients (dissolved organic carbon, total nitrogen, total phosphorus) with longer isolation age. During the initial melt there was a mean nine times enrichment in dissolved chloride relative to mean concentrations of the initial frozen holes indicative of an ionic pulse, with similar mean nine times enrichments in nitrite, ammonium, and dissolved organic matter. Nitrate was enriched twelve times and dissolved organic nitrogen six times, suggesting net nitrification, while lower enrichments for dissolved organic phosphorus and phosphate were consistent with net microbial phosphorus uptake. Rates of bacterial production were significantly elevated during the ionic pulse, likely due to the increased nutrient availability. There was no concomitant increase in photosynthesis rates, with a net depletion of dissolved inorganic carbon suggesting inorganic carbon limitation. Potential nitrogen fixation was detected in fully melted holes where it could be an important source of nitrogen to support microbial growth, but not during the ionic pulse where nitrogen availability was higher. This study demonstrates that ionic pulses significantly alter the timing and magnitude of microbial activity within entombed cryoconite holes, and adds credence to hypotheses that ionic enrichments during freeze-thaw can elevate rates of microbial growth and activity in other icy habitats, such as ice veins and subglacial regelation zones

1 aTelling, J.1 aAnesio, Alexandre, M.1 aTranter, Martyn1 aFountain, Andrew, G1 aNylen, Thomas, H.1 aHawkings, Jon1 aSingh, Virendra, B.1 aKaur, Preeti1 aMusilova, Michaela1 aWadham, J., L. uhttp://journal.frontiersin.org/article/10.3389/fmicb.2014.00694/abstract00634nas a2200181 4500008004100000245007700041210006900118260001200187490000600199100002100205700002400226700002300250700002000273700001900293700002400312700002000336856009600356 2013 eng d00aAccelerated thermokarst formation in the McMurdo Dry Valleys, Antarctica0 aAccelerated thermokarst formation in the McMurdo Dry Valleys Ant c07/20130 v31 aLevy, Joseph, S.1 aFountain, Andrew, G1 aDickson, James, L.1 aHead, James, W.1 aOkal, Marianne1 aMarchant, David, R.1 aWatters, Jaclyn uhttp://www.nature.com/srep/2013/130724/srep02269/full/srep02269.html?WT.ec_id=SREP-2013073002237nas a2200337 4500008004100000024003300041245010300074210006900177260001200246300001300258490000700271520126700278100001301545700001701558700001901575700001401594700002001608700001801628700001801646700001301664700001701677700001401694700002001708700001801728700001401746700002101760700001801781700002001799700001701819856006301836 2013 eng d ahdl: 10013 / epic.42531.d00100aAntarctic Thresholds - Ecosystem Resilience and Adaptation (AnT-ERA), a new SCAR-biology programme0 aAntarctic Thresholds Ecosystem Resilience and Adaptation AnTERA  c10/2013 a147-150.0 v823 a

Stresses on Antarctic ecosystems result from environmental change, including extreme events, and from (other) human impacts. Consequently, Antarctic habitats are changing, some at a rapid pace while others are relatively stable. A cascade of responses from molecular through organismic to the community level are expected. The differences in biological complexity and evolutionary histories between both polar regions and the rest of the planet suggest that stresses on polar ecosystem function may have fundamentally different outcomes from those at lower latitudes. Polar ecosystem processes are therefore key to informing wider ecological debate about the nature of stability and potential changes across the biosphere. The main goal of AnT-ERA is to facilitate the science required to examine changes in biological processes in Antarctic and sub-Antarctic marine-, freshwater and terrestrial ecosystems. Tolerance limits, as well as thresholds, resistance and resilience to environmental change will be determined. AnT-ERA is classified into three overlapping themes, which represent three levels of biological organisation: (1) molecular and physiological performance, (2) population processes and species traits, (3) ecosystem function and services.

1 aGutt, J.1 aAdams, Byron1 aBracegirdle, T1 aCowan, D.1 aCummings, Vonda1 adi Prisco, G.1 aGradinger, R.1 aIsla, E.1 aMcIntyre, T.1 aMurphy, E1 aPeck, Lloyd, S.1 aSchloss, I.R.1 aSmith, C.1 aSuckling, C., C.1 aTakahashi, A.1 aWall, Diana, H.1 aXavier, J.C. uhttp://epic.awi.de/34238/1/Polarforschung_82-2_147-150.pdf07866nas a2200205 4500008004100000022001400041245011200055210006900167260001200236300001400248490000700262520715200269100001907421700001907440700001807459700002707477700001807504700002107522856011707543 2013 eng d a1380-616500aCarbon Sequestration and Release from Antarctic Lakes: Lake Vida and West Lake Bonney (McMurdo Dry Valleys)0 aCarbon Sequestration and Release from Antarctic Lakes Lake Vida  c03/2013 a135 - 1450 v193 a

Perennial ice covers on many Antarctic lakes have resulted in high lake inorganic carbon contents. The objective of this paper was to evaluate and compare the brine and CO2 chemistries of Lake Vida (Victoria Valley) and West Lake Bonney (Taylor Valley), two lakes of the McMurdo Dry Valleys (East Antarctica), and their potential consequences during global warming. An existing geochemical model (FREZCHEM-15) was used to convert measured molarity into molality needed for the FREZCHEM model, and this model added a new algorithm that converts measured DIC into carbonate alkalinity needed for the FREZCHEM model. While quite extensive geochemical information exists for ice-covered Taylor Valley lakes, such as West Lake Bonney, only limited information exists for the recently sampled brine of >25 m ice-thick Lake Vida. Lake Vida brine had a model-calculated pCO2 = 0.60 bars at the field pH (6.20); West Lake Bonney had a model-calculated pCO2 = 5.23 bars at the field pH (5.46). Despite the high degree of atmospheric CO2supersaturation in West Lake Bonney, it remains significantly undersaturated with the gas hydrate, CO2·6H2O, unless these gas hydrates are deep in the sediment layer or are metastable having formed under colder temperatures or greater pressures. Because of lower temperatures, Lake Vida could start forming CO2·6H2O at lower pCO2 values than West Lake Bonney; but both lakes are significantly undersaturated with the gas hydrate, CO2·6H2O. For both lakes, simulation of global warming from current subzero temperatures (−13.4 °C in Lake Vida and −4.7 °C in West Lake Bonney) to 10 °C has shown that a major loss of solution-phase carbon as CO2 gases and carbonate minerals occurred when the temperatures rose above 0 °C and perennial ice covers would disappear. How important these Antarctic CO2 sources will be for future global warming remains to be seen. But a recent paper has shown that methane increased in atmospheric concentration due to deglaciation about 10,000 years ago. So, CO2 release from ice lakes might contribute to atmospheric gases in the future.

1 aMarion, G., M.1 aMurray, A., E.1 aWagner, Bernd1 aFritsen, Christian, H.1 aKenig, Fabien1 aDoran, Peter, T. uhttp://link.springer.com/10.1007/s10498-012-9184-1http://link.springer.com/content/pdf/10.1007/s10498-012-9184-100663nas a2200193 4500008004100000245008400041210006900125260001200194300001200206490000700218100001700225700001700242700001700259700001900276700002400295700001900319700002400338856010700362 2013 eng d00aThe carbon stable isotope biogeochemistry of streams, Taylor Valley, Antarctica0 acarbon stable isotope biogeochemistry of streams Taylor Valley A c05/2013 a26 - 360 v321 aLyons, Berry1 aLeslie, D.L.1 aHarmon, R.S.1 aNeumann, Klaus1 aWelch, Kathleen, A.1 aBisson, K., M.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/carbon-stable-isotope-biogeochemistry-streams-taylor-valley-antarctica00502nas a2200133 4500008004100000245007800041210006900119260000900188300001400197490000700211100002600218700002100244856010300265 2013 eng d00aDistribution of Siliceous-Walled Algae in Taylor Valley, Antarctica Lakes0 aDistribution of SiliceousWalled Algae in Taylor Valley Antarctic c2013 a688 - 6990 v041 aWarnock, Jonathan, P.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/distribution-siliceous-walled-algae-taylor-valley-antarctica-lakes00735nas a2200181 4500008004100000245015100041210006900192260001200261300001400273490000700287100002300294700002000317700002400337700002400361700002400385700001700409856012700426 2013 eng d00aDo Cryoconite Holes have the Potential to be Significant Sources of C, N, and P to Downstream Depauperate Ecosystems of Taylor Valley, Antarctica?0 aDo Cryoconite Holes have the Potential to be Significant Sources c11/2013 a440 - 4540 v451 aBagshaw, Elizabeth1 aTranter, Martyn1 aFountain, Andrew, G1 aWelch, Kathleen, A.1 aBasagic, Hassan, J.1 aLyons, Berry uhttps://mcm.lternet.edu/content/do-cryoconite-holes-have-potential-be-significant-sources-c-n-and-p-downstream-depauperate00566nas a2200133 4500008004100000245013000041210006900171260001200240300001400252490000700266100002200273700002000295856011700315 2013 eng d00aThe future of soil invertebrate communities in polar regions: different climate change responses in the Arctic and Antarctic?0 afuture of soil invertebrate communities in polar regions differe c03/2013 a409 - 4190 v161 aNielsen, Uffe, N.1 aWall, Diana, H. uhttp://onlinelibrary.wiley.com/doi/10.1111/ele.12058/abstract;jsessionid=2591020317030CE8FCDC37FE39B4F0B2.f01t0400638nas a2200169 4500008004100000245013200041210006900173260001200242300001600254490000800270100002100278700002400299700002100323700002400344700001700368856008300385 2013 eng d00aGarwood Valley, Antarctica: A new record of Last Glacial Maximum to Holocene glaciofluvial processes in the McMurdo Dry Valleys0 aGarwood Valley Antarctica A new record of Last Glacial Maximum t c09/2013 a1484 - 15020 v1251 aLevy, Joseph, S.1 aFountain, Andrew, G1 aO'Connor, J., E.1 aWelch, Kathleen, A.1 aLyons, Berry uhttp://bulletin.geoscienceworld.org/content/early/2013/06/07/B30783.1.abstract00533nas a2200157 4500008004100000245009000041210006900131260001300200300001000213490000700223100002500230700001700255700002600272700002000298856005700318 2013 eng d00aThe Life Cycle of the Antarctic Nematode Plectus murrayi Under Laboratory Conditions.0 aLife Cycle of the Antarctic Nematode Plectus murrayi Under Labor c2013 Mar a39-420 v451 aTomasel, Cecilia, M.1 aAdams, Byron1 aTomasel, Fernando, G.1 aWall, Diana, H. uhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC3625130/00730nas a2200193 4500008004100000245009900041210006900140300001100209100002100220700002400241700002500265700002200290700002200312700002400334700001700358700002200375700002000397856011900417 2013 eng d00aWater track modification of soil ecosystems in the Lake Hoare basin, Taylor Valley, Antarctica0 aWater track modification of soil ecosystems in the Lake Hoare ba a1 - 101 aLevy, Joseph, S.1 aFountain, Andrew, G1 aGooseff, Michael, N.1 aBarrett, John, E.1 aVantreese, Robert1 aWelch, Kathleen, A.1 aLyons, Berry1 aNielsen, Uffe, N.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/water-track-modification-soil-ecosystems-lake-hoare-basin-taylor-valley-antarctica00646nas a2200193 4500008004100000245007700041210006900118260001100187300001400198490001200212100002100224700002100245700002400266700002400290700002000314700002300334700002400357856007100381 2012 eng d00aAeolian flux of biotic and abiotic material in Taylor Valley, Antarctica0 aAeolian flux of biotic and abiotic material in Taylor Valley Ant c6/2012 a102 - 1110 v155-1561 aŠabacká, Marie1 aPriscu, John, C.1 aBasagic, Hassan, J.1 aFountain, Andrew, G1 aWall, Diana, H.1 aVirginia, Ross, A.1 aGreenwood, Mark, C. uhttp://www.sciencedirect.com/science/article/pii/S0169555X1100622202734nas a2200229 4500008004100000245012900041210006900170260001600239300001100255490000600266520197000272100002402242700002202266700001902288700001602307700002202323700002002345700001702365700002102382700002402403856007702427 2012 eng d00aAt Limits of Life: Multidisciplinary Insights Reveal Environmental Constraints on Biotic Diversity in Continental Antarctica0 aAt Limits of Life Multidisciplinary Insights Reveal Environmenta cJul-09-2013 ae445780 v73 a

Multitrophic communities that maintain the functionality of the extreme Antarctic terrestrial ecosystems, while the simplest of any natural community, are still challenging our knowledge about the limits to life on earth. In this study, we describe and interpret the linkage between the diversity of different trophic level communities to the geological morphology and soil geochemistry in the remote Transantarctic Mountains (Darwin Mountains, 80°S). We examined the distribution and diversity of biota (bacteria, cyanobacteria, lichens, algae, invertebrates) with respect to elevation, age of glacial drift sheets, and soil physicochemistry. Results showed an abiotic spatial gradient with respect to the diversity of the organisms across different trophic levels. More complex communities, in terms of trophic level diversity, were related to the weakly developed younger drifts (Hatherton and Britannia) with higher soil C/N ratio and lower total soluble salts content (thus lower conductivity). Our results indicate that an increase of ion concentration from younger to older drift regions drives a succession of complex to more simple communities, in terms of number of trophic levels and diversity within each group of organisms analysed. This study revealed that integrating diversity across multi-trophic levels of biotic communities with abiotic spatial heterogeneity and geological history is fundamental to understand environmental constraints influencing biological distribution in Antarctic soil ecosystems.

 
1 aMagalhaes, Catarina1 aStevens, Mark, I.1 aCary, Craig, S1 aBall, Becky1 aStorey, Bryan, C.1 aWall, Diana, H.1 aTürk, Roman1 aRuprecht, Ulrike1 ade Bello, Francesco uhttp://journals.plos.org/plosone/article?id=10.1371/journal.pone.004457804191nas a2200445 4500008004100000022001400041245005900055210005900114260001600173300001400189490000800203520302300211100002203234700001603256700001903272700001503291700001803306700002003324700001503344700001903359700001603378700001303394700001503407700001803422700001303440700002203453700001503475700001503490700002303505700001303528700001903541700001703560700001503577700001703592700001803609700002003627700001603647700002003663856006203683 2012 eng d a0036-807500aChallenges to the Future Conservation of the Antarctic0 aChallenges to the Future Conservation of the Antarctic cJan-07-2013 a158 - 1590 v3373 a

The Antarctic Treaty System, acknowledged as a successful model of cooperative regulation of one of the globe's largest commons (1), is under substantial pressure. Concerns have been raised about increased stress on Antarctic systems from global environmental change and growing interest in the region's resources (23). Although policy-makers may recognize these challenges, failure to respond in a timely way can have substantial negative consequences. We provide a horizon scan, a systematic means for identifying emerging trends and assisting decision-makers in identifying policies that address future challenges (23). Previous analyses of conservation threats in the Antarctic have been restricted to matters for which available evidence is compelling (4). We reconsider these concerns because they might escalate quickly, judging from recent rapid environmental change in parts of Antarctica and increasing human interest in the region (see the map). We then focus on a more distant time horizon.

1 aChown, Steven, L.1 aLee, J., E.1 aHughes, K., A.1 aBarnes, J.1 aBarrett, P.J.1 aBergstrom, D.M.1 aConvey, P.1 aCowan, Don, A.1 aCrosbie, K.1 aDyer, G.1 aFrenot, Y.1 aGrant, S., M.1 aHerr, D.1 aKennicutt, M., C.1 aLamers, M.1 aMurray, A.1 aPossingham, H., P.1 aReid, K.1 aRiddle, M., J.1 aRyan, P., G.1 aSanson, L.1 aShaw, J., D.1 aSparrow, M.D.1 aSummerhayes, C.1 aTerauds, A.1 aWall, Diana, H. uhttp://www.sciencemag.org/cgi/doi/10.1126/science.122282100683nas a2200205 4500008004100000245009900041210006900140260001200209100001700221700002300238700001700261700002200278700002100300700002600321700001700347700002200364700002000386700002200406856004900428 2012 eng d00aCross-biome metagenomic analyses of soil microbial communities and their functional attributes0 aCrossbiome metagenomic analyses of soil microbial communities an c11/20121 aFierer, Noah1 aLeff, Jonathan, W.1 aAdams, Byron1 aNielsen, Uffe, N.1 aBates, Scott, T.1 aLauber, Christian, L.1 aOwens, Sarah1 aGilbert, Jack, A.1 aWall, Diana, H.1 aCaporaso, Gregory uwww.pnas.org/cgi/doi/10.1073/pnas.121521011000624nas a2200181 4500008004100000245009000041210006900131260001200200300001400212490000700226100002400233700002300257700002600280700002800306700002300334700002200357856006300379 2012 eng d00aThe Disappearing Cryosphere: Impacts and Ecosystem Responses to Rapid Cryosphere Loss0 aDisappearing Cryosphere Impacts and Ecosystem Responses to Rapid c04/2012 a405 - 4150 v621 aFountain, Andrew, G1 aCampbell, John, L.1 aSchuur, Edward, A. G.1 aStammerjohn, Sharon, E.1 aWilliams, Mark, W.1 aDucklow, Hugh, W. uhttp://bioscience.oxfordjournals.org/content/62/4/405.full00640nas a2200193 4500008004100000245010100041210006900142260001200211300001000223490000600233100002200239700002000261700001700281700002300298700001600321700002500337700002400362856006000386 2012 eng d00aThe ecology of pulse events: insights from an extreme climatic event in a polar desert ecosystem0 aecology of pulse events insights from an extreme climatic event  c02/2012 aart170 v31 aNielsen, Uffe, N.1 aWall, Diana, H.1 aAdams, Byron1 aVirginia, Ross, A.1 aBall, Becky1 aGooseff, Michael, N.1 aMcKnight, Diane, M. uhttp://www.esajournals.org/doi/abs/10.1890/ES11-00325.100743nas a2200205 4500008004100000245013500041210006900176260001200245300001600257490000700273100002100280700002200301700002500323700002400348700002200372700002000394700002400414700002400438856007500462 2012 eng d00aExtreme streams: flow intermittency as a control on diatom communities in meltwater streams in the McMurdo Dry Valleys, Antarctica0 aExtreme streams flow intermittency as a control on diatom commun c08/2012 a1405 - 14190 v691 aStanish, Lee, F.1 aKohler, Tyler, J.1 aEsposito, Rhea, M.M.1 aSimmons, Breana, L.1 aNielsen, Uffe, N.1 aWall, Diana, H.1 aNemergut, Diana, R.1 aMcKnight, Diane, M. uhttp://www.nrcresearchpress.com/doi/abs/10.1139/f2012-022#.UH2NlWcnq9g00619nas a2200193 4500008004100000245006400041210005800105260001100163300001100174490000700185100001700192700002400209700002900233700001700262700002400279700001600303700002100319856008500340 2012 eng d00aThe geochemistry of upland ponds, Taylor Valley, Antarctica0 ageochemistry of upland ponds Taylor Valley Antarctica c2/2012 a3 - 140 v241 aLyons, Berry1 aWelch, Kathleen, A.1 aGardner, Christopher, B.1 aJaros, Chris1 aMoorhead, Daryl, L.1 aKnoepfle, J1 aDoran, Peter, T. uhttp://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=848335100514nas a2200145 4500008004100000245006300041210005600104260001200160490000700172100002100179700002400200700002400224700001700248856010300265 2012 eng d00aHypersaline “wet patches” in Taylor Valley, Antarctica0 aHypersaline wet patches in Taylor Valley Antarctica c03/20120 v391 aLevy, Joseph, S.1 aFountain, Andrew, G1 aWelch, Kathleen, A.1 aLyons, Berry uhttps://mcm.lternet.edu/content/hypersaline-%E2%80%9Cwet-patches%E2%80%9D-taylor-valley-antarctica00350nas a2200121 4500008004100000245003400041210003400075260001200109300001400121490000700135100002000142856006600162 2012 eng d00aLeaving scientific footprints0 aLeaving scientific footprints c11/2012 a502 - 5030 v101 aWall, Diana, H. uhttps://mcm.lternet.edu/content/leaving-scientific-footprints01017nas a2200337 4500008004100000022001400041245007500055210006900130260001200199300001800211490000800229100001900237700001800256700002700274700002700301700002300328700002000351700001900371700002400390700002500414700001700439700001800456700002100474700002700495700002400522700001800546700001900564700001900583700002100602856005600623 2012 eng d a0027-842400aMicrobial life at -13  C in the brine of an ice-sealed Antarctic lake0 aMicrobial life at 13 C in the brine of an icesealed Antarctic la c12/2012 a20626 - 206310 v1091 aMurray, A., E.1 aKenig, Fabien1 aFritsen, Christian, H.1 aMcKay, Christopher, P.1 aCawley, Kaelin, M.1 aEdwards, R., L.1 aKuhn, Emanuele1 aMcKnight, Diane, M.1 aOstrom, Nathaniel, E1 aPeng, Vivian1 aPonce, Adrian1 aPriscu, John, C.1 aSamarkin, Vladimir, A.1 aTownsend, Ashley, T1 aWagh, Protima1 aYoung, Seth, A1 aYung, Pung, To1 aDoran, Peter, T. uhttp://www.pnas.org/cgi/doi/10.1073/pnas.120860710901724nam a2200385 4500008004100000020002200041245011900063210006900182260005100251300001400302490000900316520052100325100002500846700002200871700001900893700002500912700002700937700002000964700002300984700002101007700002101028700001801049700001901067700001901086700001901105700002201124700001401146700002001160700002101180700002101201700002001222700001901242700001901261856005801280 2012 eng d a978-3-642-33179-400aPoisson Reconstruction of Extreme Submersed Environments: The ENDURANCE Exploration of an Under-Ice Antarctic Lake0 aPoisson Reconstruction of Extreme Submersed Environments The END aBerlin, HeidelbergbSpringer Berlin Heidelberg a394 - 4030 v74313 a

We evaluate the use of Poisson reconstruction to generate a 3D bathymetric model of West Lake Bonney, Antarctica. The source sonar dataset has been collected by the ENDURANCE autonomous ve- hicle in the course of two Antarctic summer missions. The reconstruction workflow involved processing 200 million datapoints to generate a high resolution model of the lake bottom, Narrows region and underwater glacier face. A novel and flexible toolset has been developed to automate the processing of the Bonney data.

1 aFebretti, Alessandro1 aRichmond, Kristof1 aGulati, Shilpa1 aFlesher, Christopher1 aHogan, Bartholomew, P.1 aJohnson, Andrew1 aStone, William, C.1 aPriscu, John, C.1 aDoran, Peter, T.1 aBebis, George1 aBoyle, Richard1 aParvin, Bahram1 aKoracin, Darko1 aFowlkes, Charless1 aWang, Sen1 aChoi, Min-Hyung1 aMantler, Stephan1 aSchulze, Jürgen1 aAcevedo, Daniel1 aMueller, Klaus1 aPapka, Michael uhttp://www.springerlink.com/content/hg97w43588229087/00626nas a2200181 4500008004100000245012300041210006900164260001100233300001200244490000700256100001600263700002000279700001200299700001700311700002200328700002300350856007100373 2012 eng d00aThawing permafrost alters nematode populations and soil habitat characteristics in an Antarctic polar desert ecosystem0 aThawing permafrost alters nematode populations and soil habitat  c3/2012 a75 - 810 v551 aSmith, T.E.1 aWall, Diana, H.1 aHogg, I1 aAdams, Byron1 aNielsen, Uffe, N.1 aVirginia, Ross, A. uhttp://www.sciencedirect.com/science/article/pii/S003140561100115600530nas a2200157 4500008004100000245008700041210006900128260001200197300001600209490000700225100002200232700002000254700001700274700002300291856005800314 2011 eng d00aAntarctic nematode communities: observed and predicted responses to climate change0 aAntarctic nematode communities observed and predicted responses  c11/2011 a1701 - 17110 v341 aNielsen, Uffe, N.1 aWall, Diana, H.1 aAdams, Byron1 aVirginia, Ross, A. uhttp://www.springerlink.com/content/v588t5671p1w1323/00722nas a2200193 4500008004100000245012800041210006900169260001200238300001400250490000700264100002300271700001900294700001500313700002000328700001600348700002400364700001600388856012400404 2011 eng d00aDetermination of Dissolved Oxygen in the Cryosphere: A Comprehensive Laboratory and Field Evaluation of Fiber Optic Sensors0 aDetermination of Dissolved Oxygen in the Cryosphere A Comprehens c01/2011 a700 - 7050 v451 aBagshaw, Elizabeth1 aWadham, J., L.1 aMowlem, M.1 aTranter, Martyn1 aEveness, J.1 aFountain, Andrew, G1 aTelling, J. uhttps://mcm.lternet.edu/content/determination-dissolved-oxygen-cryosphere-comprehensive-laboratory-and-field-evaluation00443nas a2200145 4500008004100000022001400041245005700055210005700112260001200169300001600181490000700197100001800204700002000222856005500242 2011 eng d a0722-406000aGlobal change and Antarctic terrestrial biodiversity0 aGlobal change and Antarctic terrestrial biodiversity c11/2011 a1625 - 16270 v341 aHogg, Ian, D.1 aWall, Diana, H. uhttp://link.springer.com/10.1007/s00300-011-1108-900636nas a2200169 4500008004100000245009700041210006900138260001200207300001600219490000700235100002300242700002000265700001900285700002400304700001500328856012300343 2011 eng d00aHigh-resolution monitoring reveals dissolved oxygen dynamics in an Antarctic cryoconite hole0 aHighresolution monitoring reveals dissolved oxygen dynamics in a c08/2011 a2868 - 28770 v251 aBagshaw, Elizabeth1 aTranter, Martyn1 aWadham, J., L.1 aFountain, Andrew, G1 aMowlem, M. uhttps://mcm.lternet.edu/content/high-resolution-monitoring-reveals-dissolved-oxygen-dynamics-antarctic-cryoconite-hole00641nas a2200181 4500008004100000245011500041210006900156260001100225300001400236490000700250100001800257700002100275700002100296700001800317700001900335700002000354856008500374 2011 eng d00aThe Holocene environmental history of Lake Hoare, Taylor Valley, Antarctica, reconstructed from sediment cores0 aHolocene environmental history of Lake Hoare Taylor Valley Antar c6/2011 a307 - 3190 v231 aWagner, Bernd1 aOrtlepp, Sabrina1 aDoran, Peter, T.1 aKenig, Fabien1 aMelles, Martin1 aBurkemper, Andy uhttp://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=827537403517nas a2200349 4500008004100000245015900041210006900200260003400269490000900303520243200312653001502744653002002759653002402779653001402803653002802817653001702845653001302862653001402875653001402889653001302903653002402916653002002940653001402960653001702974653002102991653002103012653001503033653002003048100002503068700002503093856004903118 2011 eng d00aHydrologic controls of nutrient fluxes in glacial meltwater streams at inter-annual, seasonal, and daily timescales in the McMurdo Dry Valleys, Antarctica0 aHydrologic controls of nutrient fluxes in glacial meltwater stre bPennsylvania State University0 vM.S.3 a

In the McMurdo Dry Valleys of Antarctica, glaciers are hydrologically linked to closed-basin lakes at the valley floor by glacial meltwater streams. Streams flow through porous, well-defined channels with extensive chemically active hyporheic zones. Temporally varying dynamics of meltwater generation and sub-stream thaw depth are thought to control the potential for the hyporheic zone and benthic communities to influence transport of nutrients and dissolved ions downstream. Using the McMurdo LTER database, patterns in stream discharge, electrical conductivity (both with 15-minute sampling intervals), and solute chemistry (weekly sampling intervals) were examined on eight MDV streams from 1990-2008. Discharge and electrical conductivity values were highly variable among streams. Discharge values were highly dependent upon glacial source area, but meteorological and topographical complexities create large variability at all time scales. The longer streams were found to have much higher electrical conductivity values than the shorter streams, suggesting that there are more opportunities for hyporheic weathering reactions along longer stream reaches. Weekly sampled water solutes from each stream's entire record were plotted against the discharge recorded at the time when the sample was taken. Silicate concentrations displayed a decreasing logarithmic relationship, while nutrient concentrations had no apparent relationship. This suggests that with the exception to bioreactive solutes, the majority of hyporheic interactions could possibly be characterized by electrical conductivity and discharge. To attain information on in-stream nutrient dynamics and nutrient fluxes, glacial source water at the upper reach of Green Creek and stream outlet water at the lower reach of Green Creek were sampled hourly for two separate diel periods during the 2008-09 austral summer. Both dates were in late January under two distinct flow conditions (~0.5 L/s and ~10 L/s). Under low flow conditions, nutrient cycling was found to be uptake dominated. High flow conditions showed both uptake and regeneration with much higher nutrient loads, but as in the low flow conditions, no apparent temporal trends were found. Nutrient concentrations could not be predicted using the two parameters of discharge and electrical conductivity with in-stream nutrient dynamics likely too complicated at the sub-daily scale.

10aAntarctica10abiogeochemistry10achemical weathering10adischarge10aelectrical conductivity10aglacial melt10aglaciers10ahydrology10ahyporheic10aMCM LTER10aMcMurdo Dry Valleys10anutrient fluxes10anutrients10apolar desert10asolute chemistry10astream chemistry10astreamflow10awater chemistry1 aWeaver, Mitchell, R.1 aGooseff, Michael, N. uhttps://etda.libraries.psu.edu/catalog/1156800609nas a2200169 4500008004100000022001400041245010500055210006900160260001200229490002400241100001600265700002200281700002500303700002300328700002000351856006800371 2011 eng d a0800-039500aImplications of meltwater pulse events for soil biology and biogeochemical cycling in a polar desert0 aImplications of meltwater pulse events for soil biology and biog c12/20110 v30812810303525113401 aBall, Becky1 aBarrett, John, E.1 aGooseff, Michael, N.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttp://www.polarresearch.net/index.php/polar/article/view/1455500651nas a2200205 4500008004100000022001400041245007900055210006900134260001200203300000800215490000700223100002000230700001700250700002200267700001800289700002700307700002100334700002500355856006500380 2011 eng d a0954-102000aLong-term ecosystem networks to record change: an international imperative0 aLongterm ecosystem networks to record change an international im c06/2011 a2090 v231 aWall, Diana, H.1 aLyons, Berry1 aChown, Steven, L.1 aConvey, Peter1 aHoward-Williams, Clive1 aQuesada, Antonio1 aVincent, Warwick, F. uhttp://www.journals.cambridge.org/abstract_S095410201100031900668nas a2200205 4500008004100000022001400041245010700055210006900162260001200231300001600243490000700259100001900266700001600285700001800301700002400319700002000343700002400363700002000387856005500407 2011 eng d a0722-406000aMicroclimate impacts of passive warming methods in Antarctica: implications for climate change studies0 aMicroclimate impacts of passive warming methods in Antarctica im c10/2011 a1421 - 14350 v341 aBokhorst, Stef1 aHuiskes, Ad1 aConvey, Peter1 aSinclair, Brent, J.1 aLebouvier, Marc1 aVan de Vijver, Bart1 aWall, Diana, H. uhttp://link.springer.com/10.1007/s00300-011-0997-y00627nam a2200145 4500008004100000245012700041210006900168260002200237300001400259100002500273700001700298700001800315700002000333856012800353 2011 eng d00aMolecular and physiological basis of nematode survival: Molecular analyses of desiccation survival in Antarctic nematodes.0 aMolecular and physiological basis of nematode survival Molecular aWallingfordbCABI a205 - 2321 aAdhikari, Bishwo, N.1 aAdams, Byron1 aPerry, R., N.1 aWharton, D., A. uhttps://mcm.lternet.edu/content/molecular-and-physiological-basis-nematode-survival-molecular-analyses-desiccation-survival00597nas a2200169 4500008004100000245007600041210006900117260001200186300001800198490000800216100001600224700001800240700002600258700002000284700002100304856010200325 2011 eng d00aMolecular study of worldwide distribution and diversity of soil animals0 aMolecular study of worldwide distribution and diversity of soil  c10/2011 a17720 - 177250 v1081 aWu, Tiehang1 aAyres, Edward1 aBardgett, Richard, D.1 aWall, Diana, H.1 aGarey, James, R. uhttps://mcm.lternet.edu/content/molecular-study-worldwide-distribution-and-diversity-soil-animals00632nas a2200181 4500008004100000245008400041210006900125260001100194300001400205490000700219100002200226700002000248700001400268700001700282700001700299700002300316856011100339 2011 eng d00aNematode communities of Byers Peninsula, Livingston Island, maritime Antarctica0 aNematode communities of Byers Peninsula Livingston Island mariti c8/2011 a349 - 3570 v231 aNielsen, Uffe, N.1 aWall, Diana, H.1 aLi, Grace1 aToro, Manuel1 aAdams, Byron1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/nematode-communities-byers-peninsula-livingston-island-maritime-antarctica00630nas a2200169 4500008004100000245013600041210006900177260001200246300001400258490000800272100002100280700002400301700002500325700002400350700001700374856006900391 2011 eng d00aWater tracks and permafrost in Taylor Valley, Antarctica: Extensive and shallow groundwater connectivity in a cold desert ecosystem0 aWater tracks and permafrost in Taylor Valley Antarctica Extensiv c11/2011 a2295-23110 v1231 aLevy, Joseph, S.1 aFountain, Andrew, G1 aGooseff, Michael, N.1 aWelch, Kathleen, A.1 aLyons, Berry uhttp://bulletin.geoscienceworld.org/content/123/11-12/2295.short00639nas a2200169 4500008004100000245009600041210006900137260001200206300002800218490000900246100002500255700002500280700001000305700002000315700001700335856011700352 2010 eng d00aThe Antarctic Nematode Plectus murrayi: An Emerging Model to Study Multiple Stress Survival0 aAntarctic Nematode Plectus murrayi An Emerging Model to Study Mu c11/2010 apdb.emo142 - pdb.emo1420 v20101 aAdhikari, Bishwo, N.1 aTomasel, Cecilia, M.1 aLi, G1 aWall, Diana, H.1 aAdams, Byron uhttps://mcm.lternet.edu/content/antarctic-nematode-plectus-murrayi-emerging-model-study-multiple-stress-survival00620nas a2200205 4500008004100000245005400041210005300095260000900148490000700157100001900164700002000183700001600203700001900219700002100238700001700259700001400276700001300290700002600303856008500329 2010 eng d00aBiogeochemical weathering under ice: Size matters0 aBiogeochemical weathering under ice Size matters c20100 v241 aWadham, J., L.1 aTranter, Martyn1 aSkidmore, M1 aHodson, A., J.1 aPriscu, John, C.1 aLyons, Berry1 aSharp, M.1 aWynn, P.1 aJackson, Margaret, S. uhttps://mcm.lternet.edu/content/biogeochemical-weathering-under-ice-size-matters00534nas a2200169 4500008004100000245005300041210005300094260001200147300003200159490000900191100002500200700002500225700001000250700002000260700001700280856006700297 2010 eng d00aCulturing the Antarctic Nematode Plectus murrayi0 aCulturing the Antarctic Nematode Plectus murrayi c11/2010 apdb.prot5522 - 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18120 v2131 aAdhikari, Bishwo, N.1 aWall, Diana, H.1 aAdams, Byron uhttps://mcm.lternet.edu/content/effect-slow-desiccation-and-freezing-gene-transcription-and-stress-survival-antarctic00756nas a2200205 4500008004100000245011700041210006900158260001100227300001400238490000700252100001800259700002200277700002000299700001700319700002200336700002400358700002300382700002400405856012100429 2010 eng d00aExperimentally increased snow accumulation alters soil moisture and animal community structure in a polar desert0 aExperimentally increased snow accumulation alters soil moisture  c7/2010 a897 - 9070 v331 aAyres, Edward1 aNkem, Johnson, N.1 aWall, Diana, H.1 aAdams, Byron1 aBarrett, John, E.1 aSimmons, Breana, L.1 aVirginia, Ross, A.1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/experimentally-increased-snow-accumulation-alters-soil-moisture-and-animal-community00643nas a2200169 4500008004100000245011300041210006900154260001200223300001400235490000700249100001800256700002100274700001800295700002100313700001900334856012000353 2010 eng d00aPalaeoenvironmental implications derived from a piston core from east lobe Bonney, Taylor Valley, Antarctica0 aPalaeoenvironmental implications derived from a piston core from c10/2010 a522 - 5300 v221 aWagner, Bernd1 aOrtlepp, Sabrina1 aKenig, Fabien1 aDoran, Peter, T.1 aMelles, Martin uhttps://mcm.lternet.edu/content/palaeoenvironmental-implications-derived-piston-core-east-lobe-bonney-taylor-valley00685nas a2200193 4500008004100000245010500041210006900146260001200215300001400227490000700241100002400248700001700272700001900289700002900308700002500337700002400362700002100386856008400407 2010 eng d00aSpatial variations in the geochemistry of glacial meltwater streams in the Taylor Valley, Antarctica0 aSpatial variations in the geochemistry of glacial meltwater stre c12/2010 a662 - 6720 v221 aWelch, Kathleen, A.1 aLyons, Berry1 aWhisner, Carla1 aGardner, Christopher, B.1 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aPriscu, John, C. uhttp://www.montana.edu/lkbonney/DOCS/Publications/WelchEtAl2010Geochemistry.pdf00918nas a2200325 4500008004100000245006400041210006300105300001200168490000700180100001700187700001600204700001400220700001600234700001500250700001400265700002500279700001500304700001300319700002000332700002600352700001600378700001700394700001900411700001300430700001500443700001200458700001500470700001500485856009200500 2009 eng d00aAccelerate Synthesis in Ecology and Environmental Sciences.0 aAccelerate Synthesis in Ecology and Environmental Sciences a699-7010 v591 aCarpenter, S1 aLundberg, P1 aMangel, M1 aMerchant, N1 aMurdoch, W1 aPalmer, M1 aPeters, Debra, P. C.1 aPickett, S1 aSmith, K1 aWall, Diana, H.1 aZimmerman, Maggie, K.1 aArmbrust, E1 aArzberger, E1 aChapin, F., S.1 aElser, J1 aHackett, E1 aIves, A1 aKareiva, P1 aLeibold, M uhttps://mcm.lternet.edu/content/accelerate-synthesis-ecology-and-environmental-sciences00627nas a2200157 4500008004100000245011700041210006900158300001400227490000700241100001500248700001800263700002100281700002100302700002400323856012200347 2009 eng d00aComposition and Biodegradation of a Synthetic Oil Spilled on the Perennial Ice Cover of Lake Fryxell, Antarctica0 aComposition and Biodegradation of a Synthetic Oil Spilled on the a2708-27130 v431 aJaraula, C1 aKenig, Fabien1 aDoran, Peter, T.1 aPriscu, John, C.1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/composition-and-biodegradation-synthetic-oil-spilled-perennial-ice-cover-lake-fryxell00495nas a2200145 4500008004100000245010200041210006900143260001200212300000700224490000700231100002500238700002000263700001700283856004900300 2009 eng d00aDesiccation survival in an Antarctic nematode: molecular analysis using expressed sequenced tags.0 aDesiccation survival in an Antarctic nematode molecular analysis c09/2009 a690 v101 aAdhikari, Bishwo, N.1 aWall, Diana, H.1 aAdams, Byron uhttp://www.biomedcentral.com/1471-2164/10/6900675nas a2200193 4500008004100000245008100041210006900122260001200191300000700203490000600210100002400216700002700240700002400267700002000291700001700311700002200328700002200350856010900372 2009 eng d00aEnvironmental DNA sequencing primers for eutardigrades and bdelloid rotifers0 aEnvironmental DNA sequencing primers for eutardigrades and bdell c11/2009 a250 v91 aRobeson, Michael, S1 aCostello, Elizabeth, K1 aFreeman, Kristen, R1 aWhiting, Jeremy1 aAdams, Byron1 aMartin, Andrew, P1 aSchmidt, Steve, K uhttps://mcm.lternet.edu/content/environmental-dna-sequencing-primers-eutardigrades-and-bdelloid-rotifers00622nas a2200157 4500008004100000245010300041210006900144300001400213490000700227100001600234700002300250700002200273700002400295700002000319856012500339 2009 eng d00aInteractions between physical and biotic factors influence CO_2 flux in Antarctic dry valley soils0 aInteractions between physical and biotic factors influence CO2 f a1510-15170 v411 aBall, Becky1 aVirginia, Ross, A.1 aBarrett, John, E.1 aParsons, Andrew, N.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/interactions-between-physical-and-biotic-factors-influence-co2-flux-antarctic-dry-valley01451nas a2200481 4500008004100000245006900041210006900110260001200179300001600191490001400207100002200221700002200243700002200265700002500287700002400312700002600336700001800362700001800380700002100398700002200419700002800441700001700469700001800486700002200504700002000526700002300546700002400569700002100593700001900614700002200633700001800655700002500673700001800698700002600716700002500742700002100767700002000788700002300808700002700831700002700858700002600885856005800911 2009 eng d00aLakes and reservoirs as regulators of carbon cycling and climate0 aLakes and reservoirs as regulators of carbon cycling and climate c11/2009 a2298–23140 v54 part 21 aTranvik, Lars, J.1 aDowning, John, A.1 aCotner, James, B.1 aLoiselle, Steven, A.1 aStriegl, Robert, G.1 aBallatore, Thomas, J.1 aDillon, Peter1 aFinlay, Kerri1 aFortino, Kenneth1 aKnoll, Lesley, B.1 aKortelainen, Pirkko, L.1 aKutser, Tiit1 aLarsen, Soren1 aLaurion, Isabelle1 aLeech, Dina, M.1 aMcCallister, Leigh1 aMcKnight, Diane, M.1 aMelack, John, M.1 aOverholt, Erin1 aPorter, Jason, A.1 aPrairie, Yves1 aRenwick, William, H.1 aRoland, Fabio1 aSherman, Bradford, S.1 aSchindler, David, W.1 aSobek, Sebastian1 aTremblay, Alain1 aVanni, Michael, J.1 aVerschoor, Antonie, M.1 avon Wachenfeldt, Eddie1 aWeyhenmeyer, Gesa, A. uhttp://aslo.org/lo/toc/vol_54/issue_6_part_2/2298.pdf00654nas a2200169 4500008004100000245010800041210006900149300001400218490000700232100002400239700002000263700001700283700001800300700002200318700002300340856012100363 2009 eng d00aLong-term experimental warming reduces soil nematode populations in the McMurdo Dry Valleys, Antarctica0 aLongterm experimental warming reduces soil nematode populations  a2052-20600 v411 aSimmons, Breana, L.1 aWall, Diana, H.1 aAdams, Byron1 aAyres, Edward1 aBarrett, John, E.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/long-term-experimental-warming-reduces-soil-nematode-populations-mcmurdo-dry-valleys00718nas a2200241 4500008004100000245007300041210006900114300001200183490000600195100001500201700001300216700001800229700002000247700001600267700001300283700001200296700001400308700001500322700001500337700001300352700001300365856009800378 2009 eng d00aManaging for ocean biodiversity to sustain marine ecosystem services0 aManaging for ocean biodiversity to sustain marine ecosystem serv a204-2110 v71 aPalumbi, S1 aNorse, E1 aStachowicz, J1 aWall, Diana, H.1 aSandifer, P1 aAllan, J1 aBeck, M1 aFautin, D1 aFogerty, M1 aHalpern, B1 aIncze, L1 aLeong, J uhttps://mcm.lternet.edu/content/managing-ocean-biodiversity-sustain-marine-ecosystem-services00480nas a2200109 4500008004100000245008700041210006900128260003000197100001600227700001700243856011000260 2009 eng d00aThe Minor Alkaline Earth Element and Alkali Metal Behavior in Closed-basin Lakes0 aMinor Alkaline Earth Element and Alkali Metal Behavior in Closed bThe Ohio State University1 aWitherow, R1 aLyons, Berry uhttps://mcm.lternet.edu/content/minor-alkaline-earth-element-and-alkali-metal-behavior-closed-basin-lakes00633nas a2200157 4500008004100000245012400041210006900165300001200234100001000246700001800256700001000274700002600284700002000310700002100330856012400351 2009 eng d00aMolecular profiling of soil animal diversity in natural ecosystems: incongruence of molecular and morphological results0 aMolecular profiling of soil animal diversity in natural ecosyste a849-8571 aWu, T1 aAyres, Edward1 aLi, G1 aBardgett, Richard, D.1 aWall, Diana, H.1 aGarey, James, R. uhttps://mcm.lternet.edu/content/molecular-profiling-soil-animal-diversity-natural-ecosystems-incongruence-molecular-and00835nas a2200289 4500008004100000245006600041210006500107490000700172100002300179700002000202700001600222700001600238700001700254700001400271700001200285700001200297700001700309700001600326700001900342700001400361700001300375700002200388700001500410700001500425700001900440856008600459 2009 eng d00aState of the Antarctic and the Southern Ocean climate system,0 aState of the Antarctic and the Southern Ocean climate system0 v471 aMayewski, Paul, A.1 aBromwich, David1 aCampbell, H1 aHamilton, G1 aLyons, Berry1 aMaasch, K1 aAoki, S1 aXiao, C1 avan Ommen, T1 aMeredith, M1 aSummerhayes, C1 aTurner, J1 aWorby, A1 aBarrett, John, E.1 aCasassa, G1 aBertler, N1 aBracegirdle, T uhttps://mcm.lternet.edu/content/state-antarctic-and-southern-ocean-climate-system00629nas a2200169 4500008004100000245008900041210006900130300001400199490000700213100002400220700002000244700001700264700001800281700002200299700002300321856011500344 2009 eng d00aTerrestrial mesofauna in above- and below-ground habitats: Taylor Valley, Antarctica0 aTerrestrial mesofauna in above and belowground habitats Taylor V a1549-15580 v321 aSimmons, Breana, L.1 aWall, Diana, H.1 aAdams, Byron1 aAyres, Edward1 aBarrett, John, E.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/terrestrial-mesofauna-above-and-below-ground-habitats-taylor-valley-antarctica00528nas a2200109 4500008004100000245011900041210006900160260003000229100001400259700002000273856012500293 2008 eng d00aA comparison of anhydrobiosis in nematodes of the McMurdo Dry Valleys, Antarctica and Short Grass Steppe, Colorado0 acomparison of anhydrobiosis in nematodes of the McMurdo Dry Vall bColorado School of Mines,1 aSeaver, K1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/comparison-anhydrobiosis-nematodes-mcmurdo-dry-valleys-antarctica-and-short-grass-steppe00606nas a2200145 4500008004100000245011900041210006900160300001400229490000700243100002200250700002300272700002000295700001700315856012800332 2008 eng d00aDecline in a dominant invertebrate species contributes to altered carbon cycling in a low-diversity soil ecosystem0 aDecline in a dominant invertebrate species contributes to altere a1734-17440 v141 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aAdams, Byron uhttps://mcm.lternet.edu/content/decline-dominant-invertebrate-species-contributes-altered-carbon-cycling-low-diversity-soil02709nas a2200241 4500008004100000245010000041210006900141260001200210300001400222490000700236520190500243100001802148700002202166700002002188700001702208700002202225700001302247700002402260700002202284700002402306700002302330856011402353 2008 eng d00aEffects of Human Trampling on Populations of Soil Fauna in the McMurdo Dry Valleys, Antarctica.0 aEffects of Human Trampling on Populations of Soil Fauna in the M c12/2008 a1544-15510 v223 a

Antarctic ecosystems are often considered nearly pristine because levels of anthropogenic disturbance are extremely low there. Nevertheless, over recent decades there has been a rapid increase in the number of people, researchers and tourists, visiting Antarctica. We evaluated, over 10 years, the direct impact of foot traffic on the abundance of soil animals and soil properties in Taylor Valley within the McMurdo Dry Valleys region of Antarctica. We compared soils from minimally disturbed areas with soils from nearby paths that received intermediate and high levels of human foot traffic (i.e., up to approximately 80 passes per year). The nematodes Scottnema lindsayae and Eudorylaimus sp. were the most commonly found animal species, whereas rotifers and tardigrades were found only occasionally. On the highly trampled footpaths, abundance of S. lindsayae and Eudorylaimus sp. was up to 52 and 76% lower, respectively, than in untrampled areas. Moreover, reduction in S. lindsayae abundance was more pronounced after 10 years than 2 years and in the surface soil than in the deeper soil, presumably because of the longer period of disturbance and the greater level of physical disturbance experienced by the surface soil. The ratio of living to dead Eudorylaimus sp. also declined with increased trampling intensity, which is indicative of increased mortality or reduced fecundity. At one site there was evidence that high levels of trampling reduced soil CO2 fluxes, which is related to total biological activity in the soil. Our results show that even low levels of human traffic can significantly affect soil biota in this ecosystem and may alter ecosystem processes, such as carbon cycling. Consequently, management and conservation plans for Antarctic soils should consider the high sensitivity of soil fauna to physical disturbance as human presence in this ecosystem increases.

1 aAyres, Edward1 aNkem, Johnson, N.1 aWall, Diana, H.1 aAdams, Byron1 aBarrett, John, E.1 aBroos, E1 aParsons, Andrew, N.1 aPowers, Laura, E.1 aSimmons, Breana, L.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/effects-human-trampling-populations-soil-fauna-mcmurdo-dry-valleys-antarctica01642nas a2200541 4500008004100000245010100041210006900142260001200211300001400223490000700237100002000244700002300264700002100287700002300308700002900331700002300360700002200383700002400405700001700429700002000446700002100466700002600487700002000513700002200533700002400555700002400579700001900603700002200622700002200644700002100666700001700687700002200704700002300726700001500749700001900764700002100783700002100804700002400825700002200849700002300871700002600894700002300920700001900943700002900962700001500991700001701006856007701023 2008 eng d00aGlobal decomposition experiment shows soil animal impacts on decomposition are climate dependent0 aGlobal decomposition experiment shows soil animal impacts on dec c11/2008 a2661-26770 v141 aWall, Diana, H.1 aBradford, Mark, A.1 aStJohn, Mark, G.1 aTrofymow, John, A.1 aBehan-Pelletier, Valerie1 aBignell, David, E.1 aDangerfield, Mark1 aParton, William, J.1 aRusek, Josef1 aVoigt, Winfried1 aWolters, Volkmar1 aGardel, Holley, Zadeh1 aAyuke, Fred, O.1 aBashford, Richard1 aBeljakova, Olga, I.1 aBohlen, Patrick, J.1 aBrauman, Alain1 aFlemming, Stephen1 aHenschel, Joh, R.1 aJohnson, Dan, L.1 aJones, Hefin1 aKovarova, Marcela1 aKranabetter, Marty1 aKutny, Les1 aLin, Kuo-Chuan1 aMaryati, Mohamed1 aMasse, Dominique1 aPokarzhevsk, Andrei1 aRahman, Homathevi1 aSabara, Millor, G.1 aSalamon, Joerg-Alfred1 aSwift, Michael, J.1 aVarela, Amanda1 aVasconcelos, Heraldo, L.1 aWhite, Don1 aZou, Xiaming uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2008.01672.x/full00591nas a2200157 4500008004100000245009700041210006900138260001200207300001200219490000700231100001300238700002200251700002300273700002000296856011700316 2008 eng d00aThe influence of soil geochemistry on nematode distribution, McMurdo Dry Valleys, Antarctica0 ainfluence of soil geochemistry on nematode distribution McMurdo  c02/2008 a119-1280 v401 aPoage, M1 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/influence-soil-geochemistry-nematode-distribution-mcmurdo-dry-valleys-antarctica00672nas a2200193 4500008004100000245008200041210006900123300001400192490000700206100002500213700002500238700002400263700001700287700001600304700001600320700002100336700001700357856010400374 2008 eng d00aInland diatoms from the McMurdo Dry Valleys and James Ross Island, Antarctica0 aInland diatoms from the McMurdo Dry Valleys and James Ross Islan a1378-13920 v121 aEsposito, Rhea, M.M.1 aSpaulding, Sarah, A.1 aMcKnight, Diane, M.1 aDe Vijver, B1 aKopalova, K1 aLubinski, D1 aHall, Brenda, L.1 aWhittaker, T uhttps://mcm.lternet.edu/content/inland-diatoms-mcmurdo-dry-valleys-and-james-ross-island-antarctica00397nas a2200121 4500008004100000245005100041210005100092300001400143490000700157100001600164700001700180856007800197 2008 eng d00aMercury Deposition in a Polar Desert Ecosystem0 aMercury Deposition in a Polar Desert Ecosystem a4710-47160 v421 aWitherow, R1 aLyons, Berry uhttps://mcm.lternet.edu/content/mercury-deposition-polar-desert-ecosystem00626nas a2200181 4500008004100000245008300041210006900124300001400193490000700207100002000214700001600234700001400250700001100264700002200275700002000297700001900317856010800336 2008 eng d00aMicrobial community composition in soils of Northern Victoria Land, Antarctica0 aMicrobial community composition in soils of Northern Victoria La a1713-17240 v101 aNiederberger, T1 aMcDonald, i1 aHacker, A1 aSoo, R1 aBarrett, John, E.1 aWall, Diana, H.1 aCary, Craig, S uhttps://mcm.lternet.edu/content/microbial-community-composition-soils-northern-victoria-land-antarctica00595nas a2200169 4500008004100000245008100041210006900122260001200191300001400203490000700217653002100224653001400245100002200259700002300281700002000304856010100324 2008 eng d00aPersistent effects of a discrete climate event on a polar desert ecosystem0 aPersistent effects of a discrete climate event on a polar desert c06/2008 a2249-22610 v1410aClimate Response10anematodes1 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/persistent-effects-discrete-climate-event-polar-desert-ecosystem00556nas a2200121 4500008004100000245011000041210006900151260003600220490000900256100002600265700002100291856012200312 2008 eng d00aProvenance of organic matter in Taylor Valley, Antarctica lakes: Scanning Electron Microscopy of sediment0 aProvenance of organic matter in Taylor Valley Antarctica lakes S bUniversity of Illinois, Chicago0 vM.S.1 aWarnock, Jonathan, P.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/provenance-organic-matter-taylor-valley-antarctica-lakes-scanning-electron-microscopy00645nas a2200157 4500008004100000245012900041210006900170300001200239490000800251100001500259700001800274700002100292700002100313700002400334856012900358 2008 eng d00aSPME-GCMS study of the natural attenuation of aviation diesel spilled on the perennial ice cover of Lake Fryxell, Antarctica0 aSPMEGCMS study of the natural attenuation of aviation diesel spi a250-2620 v4071 aJaraula, C1 aKenig, Fabien1 aDoran, Peter, T.1 aPriscu, John, C.1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/spme-gcms-study-natural-attenuation-aviation-diesel-spilled-perennial-ice-cover-lake-fryxell00949nas a2200349 4500008004100000245005900041210005800100300001400158490000700172100001800179700001300197700001500210700001400225700001500239700001400254700001400268700001600282700003300298700001500331700001900346700001400365700001100379700002200390700001700412700001300429700001500442700001600457700001600473700001400489700001200503856008400515 2008 eng d00aStoichiometry of soil enzyme activity at global scale.0 aStoichiometry of soil enzyme activity at global scale a1252-12640 v111 aSinsabaugh, R1 aGallo, M1 aGartner, T1 aHobbie, S1 aHolland, K1 aKeeler, B1 aPowers, J1 aStursova, M1 aTakacs-Vesbach, Cristina, D.1 aWaldrop, M1 aWallenstein, M1 aLauber, M1 aZak, D1 aZeglin, Lydia, H.1 aWeintraub, M1 aAhmed, B1 aAllison, S1 aCrenshaw, C1 aContosta, A1 aCusack, D1 aFrey, S uhttps://mcm.lternet.edu/content/stoichiometry-soil-enzyme-activity-global-scale00658nas a2200181 4500008004100000245013600041210006900177300001400246490000700260100002100267700002500288700001900313700002400332700002000356700002500376700001700401856005800418 2008 eng d00aSupersaturated N2O in a perennially ice-covered Antarctic lake: Molecular and stable isotopic evidence for a biogeochemical relict.0 aSupersaturated N2O in a perennially icecovered Antarctic lake Mo a2439-24500 v531 aPriscu, John, C.1 aChristner, Brent, C.1 aDore, John, E.1 aWestley, Marian, B.1 aPopp, Brian, N.1 aCasciotti, Karen, L.1 aLyons, Berry uhttp://brent.xner.net/pdf/Priscu_etal2008_ELB-N2O.pdf00637nas a2200169 4500008004100000245009400041210006900135300001100204490000800215100002300223700002000246700002400266700002400290700002400314700001700338856011200355 2007 eng d00aThe biogeochemical evolution of cryoconite holes on glaciers in Taylor Valley, Antarctica0 abiogeochemical evolution of cryoconite holes on glaciers in Tayl aG04S350 v1131 aBagshaw, Elizabeth1 aTranter, Martyn1 aFountain, Andrew, G1 aWelch, Kathleen, A.1 aBasagic, Hassan, J.1 aLyons, Berry uhttps://mcm.lternet.edu/content/biogeochemical-evolution-cryoconite-holes-glaciers-taylor-valley-antarctica03147nas a2200241 4500008004100000245006800041210006800109260001200177300001400189490000800203520239000211653001102601100002202612700002302634700001702657700002402674700002102698700002402719700002002743700002402763700002102787856009702808 2007 eng d00aBiogeochemical stoichiometry of Antarctic Dry Valley ecosystems0 aBiogeochemical stoichiometry of Antarctic Dry Valley ecosystems c02/2007 aG01010+120 v1123 a

Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10–106 years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated by availability of liquid water, they influence the chemical composition of their environment according to these ratios. Nitrogen and phosphorus varied significantly in terrestrial and aquatic ecosystems occurring on landscape surfaces across a wide range of exposure ages, indicating strong influences of landscape development and geochemistry on nutrient availability. Biota control the elemental ratio of stream waters, while geochemical stoichiometry (e.g., weathering, atmospheric deposition) evidently limits the distribution of soil invertebrates. We present a conceptual model describing transformations across dry valley landscapes facilitated by exchanges of liquid water and biotic processing of dissolved nutrients. We conclude that contemporary ecosystem stoichiometry of Antarctic Dry Valley soils, glaciers, streams, and lakes results from a combination of extant biological processes superimposed on a legacy of landscape processes and previous climates.

10aBiggie1 aBarrett, John, E.1 aVirginia, Ross, A.1 aLyons, Berry1 aMcKnight, Diane, M.1 aPriscu, John, C.1 aFountain, Andrew, G1 aWall, Diana, H.1 aMoorhead, Daryl, L.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/biogeochemical-stoichiometry-antarctic-dry-valley-ecosystems01239nas a2200157 4500008004100000245010700041210006900148260001200217300001400229490000800243520072000251653001100971653000900982100002000991856007001011 2007 eng d00aGlobal Change tipping points: Above- and below-ground biotic interactions in a low diversity ecosystem0 aGlobal Change tipping points Above and belowground biotic intera c12/2007 a2291-23060 v3623 a

Low diversity ecosystems are expected to be more vulnerable to global changes although they have received less attention than high diversity ecosystems. Addressing the present state of the Antarctic Dry Valley region by focusing on the potential global changes that may alter the coupling of above- and below-ground species and ecosystem processes is a realistic and critical need that has value beyond the Antarctic community. Presented here are suggested implications of global change on the Dry Valley terrestrial systems and how these effects might be manifested in the future.

10aBiggie10asoil1 aWall, Diana, H. uhttp://rstb.royalsocietypublishing.org/content/362/1488/2291.full00380nas a2200109 4500008004100000245004700041210004400088260003300132100002000165700002900185856005600214 2007 eng d00aHidden Assets: Biodiversity Below-Surface.0 aHidden Assets Biodiversity BelowSurface bUNESCO-SCOPE Policy Brief #51 aWall, Diana, H.1 aBehan-Pelletier, Valerie uhttp://www.icsu-scope.org/unesco/USPB05_SOIL_En.pdf00539nas a2200145 4500008004100000245008300041210006900124300001200193490000700205100001200212700002000224700002000244700002300264856010600287 2007 eng d00aA mathematical model for variation in water-retention curves among sandy soils0 amathematical model for variation in waterretention curves among  a427-4360 v191 aHunt, H1 aTreonis, Amy, M1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/mathematical-model-variation-water-retention-curves-among-sandy-soils00393nas a2200121 4500008004100000245004600041210004600087490000700133100001700140700002400157700001500181856007500196 2007 eng d00aOrganic carbon in Antarctic precipitation0 aOrganic carbon in Antarctic precipitation0 v341 aLyons, Berry1 aWelch, Kathleen, A.1 aDoggett, J uhttps://mcm.lternet.edu/content/organic-carbon-antarctic-precipitation00763nas a2200205 4500008004100000245013200041210006900173260001200242300001200254490000700266100002400273700002000297700002400317700002000341700001600361700002400377700001700401700001900418856012000437 2007 eng d00aReactivation of a cryptobiotic stream ecosystem in the McMurdo Dry Valleys, Antarctica: A long-term geomorphological experiment0 aReactivation of a cryptobiotic stream ecosystem in the McMurdo D c09/2007 a186-2040 v891 aMcKnight, Diane, M.1 aTate, Cathy, M.1 aAndrews, Edmund, D.1 aNiyogi, Dev, K.1 aCozzetto, K1 aWelch, Kathleen, A.1 aLyons, Berry1 aCapone, D., G. uhttps://mcm.lternet.edu/content/reactivation-cryptobiotic-stream-ecosystem-mcmurdo-dry-valleys-antarctica-long-term00599nas a2200181 4500008004100000245009400041210006900135260001200204300001200216490000800228653002100236100001400257700002000271700002400291700001700315700002400332856006100356 2007 eng d00aSolute and isotope geochemistry of subsurface ice melt seeps in Taylor Valley, Antarctica0 aSolute and isotope geochemistry of subsurface ice melt seeps in  c01/2007 a548-5550 v11910aClimate Response1 aHarris, K1 aCarey, Anne, E.1 aWelch, Kathleen, A.1 aLyons, Berry1 aFountain, Andrew, G uhttp://gsabulletin.gsapubs.org/content/119/5-6/548.short00625nas a2200169 4500008004100000245010600041210006900147300001200216490000700228100001700235700002000252700001300272700001500285700001500300700001200315856012800327 2007 eng d00aThe southernmost worm, Scottnema lindsayae (Nematoda): diversity, dispersal and ecological stability.0 asouthernmost worm Scottnema lindsayae Nematoda diversity dispers a809-8150 v301 aAdams, Byron1 aWall, Diana, H.1 aGozel, U1 aDillman, A1 aChaston, J1 aHogg, I uhttps://mcm.lternet.edu/content/southernmost-worm-scottnema-lindsayae-nematoda-diversity-dispersal-and-ecological-stability00578nas a2200133 4500008004100000245011000041210006900151100001800220700002000238700001700258700002200275700002300297856012400320 2007 eng d00aUnique similarity of faunal communities across aquatic terrestrial interfaces in a polar desert ecosystem0 aUnique similarity of faunal communities across aquatic terrestri1 aAyres, Edward1 aWall, Diana, H.1 aAdams, Byron1 aBarrett, John, E.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/unique-similarity-faunal-communities-across-aquatic-terrestrial-interfaces-polar-desert00754nas a2200205 4500008004100000245012400041210006900165300001200234490000700246100001600253700001500269700002400284700001700308700002300325700001300348700002200361700001500383700002400398856012600422 2006 eng d00aThe aeolian flux of calcium, chloride and nitrate to the McMurdo Dry Valleys landscape: Evidence from snow pit analysis0 aaeolian flux of calcium chloride and nitrate to the McMurdo Dry  a497-5050 v181 aWitherow, R1 aBertler, N1 aWelch, Kathleen, A.1 aLyons, Berry1 aMayewski, Paul, A.1 aSneed, S1 aNylen, Thomas, H.1 aHandley, M1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/aeolian-flux-calcium-chloride-and-nitrate-mcmurdo-dry-valleys-landscape-evidence-snow-pit00563nas a2200169 4500008004100000245004600041210004600087260003400133100001700167700002800184700002400212700002100236700002000257700001800277700002000295856007800315 2006 eng d00aAntarctic lake systems and climate change0 aAntarctic lake systems and climate change aDordrecht, The NetherlandsbS1 aLyons, Berry1 aLaybourn-Parry, Johanna1 aWelch, Kathleen, A.1 aPriscu, John, C.1 aBergstrom, D.M.1 aConvey, Peter1 aHuiskes, A.H.L. uhttps://mcm.lternet.edu/content/antarctic-lake-systems-and-climate-change00665nas a2200217 4500008004100000245008000041210006900121300001400190490000700204100001200211700002000223700001900243700001400262700001500276700001600291700001700307700001600324700002100340700001500361856007100376 2006 eng d00aBiotic interactions in Antarctic terrestrial ecosystems: Are they a factor?0 aBiotic interactions in Antarctic terrestrial ecosystems Are they a3035-30400 v381 aHogg, I1 aWall, Diana, H.1 aCary, Craig, S1 aConvey, K1 aNewsham, K1 aODonnell, G1 aAdams, Byron1 aAislabie, J1 aFrati, Francesco1 aStevens, M uhttp://www.sciencedirect.com/science/article/pii/S003807170600217300757nas a2200181 4500008004100000245010900041210006900150300001200219490000700231100002200238700002300260700002000283700001900303700001700322700001400339700001600353856020600369 2006 eng d00aCo-variation in soil biodiversity and biogeochemistry in Northern and Southern Victoria Land, Antarctica0 aCovariation in soil biodiversity and biogeochemistry in Northern a535-5480 v181 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aCary, Craig, S1 aAdams, Byron1 aHacker, A1 aAislabie, J uhttps://www.cambridge.org/core/journals/antarctic-science/article/covariation-in-soil-biodiversity-and-biogeochemistry-in-northern-and-southern-victoria-land-antarctica/C3514C28DB75F3A19DB5F266D4B1B56E00891nas a2200325 4500008004100000245005400041210005400095300001400149490000700163100001700170700001500187700001800202700001200220700002100232700001200253700001500265700001700280700001500297700001500312700001500327700002600342700001800368700002000386700001600406700001600422700001600438700001900454700001600473856007600489 2006 eng d00aDiversity and distribution of Victoria Land biota0 aDiversity and distribution of Victoria Land biota a3003-30180 v381 aAdams, Byron1 aConnell, L1 aConvey, Peter1 aFell, J1 aFrati, Francesco1 aHogg, I1 aNewsham, K1 aO'Donnell, A1 aRussell, N1 aSeppelt, R1 aStevens, M1 aBardgett, Richard, D.1 aAyres, Edward1 aWall, Diana, H.1 aAislabie, J1 aBamforth, S1 aBargagli, R1 aCary, Craig, S1 aCavacini, P uhttps://www.sciencedirect.com/science/article/abs/pii/S003807170600221500655nas a2200181 4500008004100000245011400041210006900155300000800224490000800232100001400240700001400254700002100268700001800289700001400307700001400321700001300335856012500348 2006 eng d00aGlacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, Southern Victoria Land, Antarctica0 aGlacial and postglacial sedimentation in the Fryxell basin Taylo a3200 v3411 aWagner, B1 aMelles, M1 aDoran, Peter, T.1 aKenig, Fabien1 aForman, S1 aPierau, R1 aAllan, P uhttps://mcm.lternet.edu/content/glacial-and-postglacial-sedimentation-fryxell-basin-taylor-valley-southern-victoria-land00554nas a2200169 4500008004100000245006300041210006200104300001200166490000700178100001500185700001600200700002200216700002000238700002300258700001500281856008800296 2006 eng d00aPhosphorus fractions in soils of Taylor Valley, Antarctica0 aPhosphorus fractions in soils of Taylor Valley Antarctica a806-8150 v701 aBlecker, S1 aIppolito, J1 aBarrett, John, E.1 aWall, Diana, H.1 aVirginia, Ross, A.1 aNorvell, K uhttps://mcm.lternet.edu/content/phosphorus-fractions-soils-taylor-valley-antarctica00583nas a2200157 4500008004100000245008700041210006900128300001200197490000700209100002200216700002300238700002200261700002000283700001000303856011200313 2006 eng d00aSalt tolerance and survival thresholds for two species of Antarctic soil nematodes0 aSalt tolerance and survival thresholds for two species of Antarc a643-6510 v291 aNkem, Johnson, N.1 aVirginia, Ross, A.1 aBarrett, John, E.1 aWall, Diana, H.1 aLi, G uhttps://mcm.lternet.edu/content/salt-tolerance-and-survival-thresholds-two-species-antarctic-soil-nematodes00531nas a2200145 4500008004100000245007100041210006900112300001400181490000700195100002200202700002300224700002400247700002000271856009400291 2006 eng d00aSoil carbon turnover model for the McMurdo Dry Valleys, Antarctica0 aSoil carbon turnover model for the McMurdo Dry Valleys Antarctic a3065-30820 v381 aBarrett, John, E.1 aVirginia, Ross, A.1 aParsons, Andrew, N.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/soil-carbon-turnover-model-mcmurdo-dry-valleys-antarctica00563nas a2200145 4500008004100000245009200041210006900133300001400202490000700216100002000223700001700243700002200260700002000282856011500302 2006 eng d00aA synthesis of soil biodiversity and ecosystem functioning in Victoria Land, Antarctica0 asynthesis of soil biodiversity and ecosystem functioning in Vict a3001-30020 v381 aWall, Diana, H.1 aAdams, Byron1 aBarrett, John, E.1 aHopkins, D., W. uhttps://mcm.lternet.edu/content/synthesis-soil-biodiversity-and-ecosystem-functioning-victoria-land-antarctica00812nas a2200265 4500008004100000245006500041210006400106300001400170490000700184100002200191700002200213700001500235700001600250700002000266700001900286700002300305700002000328700001600348700001600364700001600380700001600396700001700412700002400429856009300453 2006 eng d00aTerrestrial ecosystem processes of Victoria Land, Antarctica0 aTerrestrial ecosystem processes of Victoria Land Antarctica a3019-30340 v381 aBarrett, John, E.1 aNkem, Johnson, N.1 aSletten, R1 aSteltzer, H1 aWall, Diana, H.1 aWallenstein, M1 aVirginia, Ross, A.1 aHopkins, D., W.1 aAislabie, J1 aBargagli, R1 aBockheim, J1 aCampbell, I1 aLyons, Berry1 aMoorhead, Daryl, L. uhttps://mcm.lternet.edu/content/terrestrial-ecosystem-processes-victoria-land-antarctica02560nas a2200205 4500008004100000245008000041210006900121300001200190490000700202520193000209653001102139100002202150700002002172700002302192700002202215700001302237700001802250700001702268856006902285 2006 eng d00aWind dispersal of soil invertebrates in the McMurdo Dry Valleys, Antarctica0 aWind dispersal of soil invertebrates in the McMurdo Dry Valleys  a346-3520 v293 a

Dispersal of soil organisms is crucial for their spatial distribution and adaptation to the prevailing conditions of the Antarctic Dry Valleys. This study investigated the possibility of wind dispersal of soil invertebrates within the dry valleys. Soil invertebrates were evaluated in (1) pockets of transported sediments to lake ice and glacier surfaces, (2) wind-transported dust particles in collection pans (Bundt pans) 100 cm above the soil surface, and (3) sediments transported closer to the surface (<50 cm) and collected in open top chambers (OTCs). Invertebrates were extracted and identified. Nematodes were identified to species and classified according to life stage and sex. Three species of nematodes were recovered and Scottnema lindsayae was the most dominant. There were more juveniles (∼71%) in the transported sediments than adults (29%). Tardigrades and rotifers were more abundant in sediments on lake and glacier surfaces while nematodes were more abundant in the dry sediment collections of Bundt pans and OTCs. The abundance of immobile (dead) nematodes in the Bundt pans and OTCs was three times greater than active (live) nematodes. Anhydrobiosis constitutes a survival mechanism that allows wind dispersal of nematodes in the McMurdo Dry Valleys. Our results show that soil invertebrates are dispersed by wind in the Dry Valleys and are viable in ice communities on lake surfaces and glaciers.

10aBiggie1 aNkem, Johnson, N.1 aWall, Diana, H.1 aVirginia, Ross, A.1 aBarrett, John, E.1 aBroos, E1 aPorazinska, D1 aAdams, Byron uhttp://link.springer.com/content/pdf/10.1007%2Fs00300-005-0061-x00497nas a2200121 4500008004100000245008100041210006900122260001200191300001200203490000700215100002000222856013300242 2005 eng d00aBiodiversity and ecosystem functioning in terrestrial habitats of Antarctica0 aBiodiversity and ecosystem functioning in terrestrial habitats o c07/2005 a523-5310 v171 aWall, Diana, H. uhttp://journals.cambridge.org/download.php?file=%2FANS%2FANS17_04%2FS0954102005002944a.pdf&code=f0bfb3b7eb4345bde6bbfbf916a408e100648nas a2200157 4500008004100000245012800041210006900169300001000238490000700248100002000255700002400275700001700299700002200316700002400338856012800362 2005 eng d00aThe chemical composition of runoff from Canada Glacier, Antarctica: implications for glacier hydrology during a cool summer0 achemical composition of runoff from Canada Glacier Antarctica im a15-190 v401 aTranter, Martyn1 aFountain, Andrew, G1 aLyons, Berry1 aNylen, Thomas, H.1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/chemical-composition-runoff-canada-glacier-antarctica-implications-glacier-hydrology-during00884nas a2200265 4500008004100000245007800041210007000119300001100189490000700200653002500207100002100232700001900253700002700272700002700299700002400326700002100350700001700371700001300388700002400401700002400425700002400449700002300473700002000496856010200516 2005 eng d00aComment on ``El Niño suppresses Antarctic warming'' by N. Bertler et al.0 aComment on El Niño suppresses Antarctic warming by N Bertler et  aL077060 v3210aTropical meteorology1 aDoran, Peter, T.1 aClow, Gary, D.1 aFritsen, Christian, H.1 aMcKay, Christopher, P.1 aParsons, Andrew, N.1 aPriscu, John, C.1 aLyons, Berry1 aWalsh, J1 aFountain, Andrew, G1 aMcKnight, Diane, M.1 aMoorhead, Daryl, L.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/comment-el-ni%C3%B1o-suppresses-antarctic-warming-n-bertler-et-al00618nas a2200181 4500008004100000245006900041210006800110300000900178490000700187100001700194700002100211700002400232700001400256700002300270700002100293700002400314856009800338 2005 eng d00aDating water and solute additions to ice-covered Antarctic lakes0 aDating water and solute additions to icecovered Antarctic lakes aA7200 v691 aLyons, Berry1 aDowling, Carolyn1 aWelch, Kathleen, A.1 aSnyder, G1 aPoreda, Robert, J.1 aDoran, Peter, T.1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/dating-water-and-solute-additions-ice-covered-antarctic-lakes00612nas a2200169 4500008004100000245007600041210006900117260003100186300000900217100002000226700001500246700001700261700002600278700001800304700002000322856010000342 2005 eng d00aDeveloping new perspectives from advances in soil biodiversity research0 aDeveloping new perspectives from advances in soil biodiversity r bCambridge University Press a3-301 aWall, Diana, H.1 aFritter, A1 aPaul, E., A.1 aBardgett, Richard, D.1 aUsher, M., B.1 aHopkins, D., W. uhttps://mcm.lternet.edu/content/developing-new-perspectives-advances-soil-biodiversity-research00519nas a2200133 4500008004100000245008900041210006900130300001200199490000700211100001600218700002000234700002300254856010800277 2005 eng d00aDistribution and diversity of soil protozoa in the McMurdo Dry Valleys of Antarctica0 aDistribution and diversity of soil protozoa in the McMurdo Dry V a756-7620 v281 aBamforth, S1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/distribution-and-diversity-soil-protozoa-mcmurdo-dry-valleys-antarctica00646nas a2200157 4500008004100000245013500041210006900176300001200245490000700257100001900264700002000283700002400303700001700327700002400344856012000368 2005 eng d00aThe Geochemistry of Supraglacial Streams of Canada Glacier, Taylor Valley (Antarctica), and their Evolution into Proglacial Waters0 aGeochemistry of Supraglacial Streams of Canada Glacier Taylor Va a391-4120 v111 aFortner, Sarah1 aTranter, Martyn1 aFountain, Andrew, G1 aLyons, Berry1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/geochemistry-supraglacial-streams-canada-glacier-taylor-valley-antarctica-and-their00711nas a2200205 4500008004100000245008900041210006900130300001200199490000700211100001700218700002400235700002000259700002000279700002300299700002400322700002100346700001400367700001500381856010900396 2005 eng d00aGroundwater seeps in Taylor Valley Antarctica: An example of a subsurface melt event0 aGroundwater seeps in Taylor Valley Antarctica An example of a su a200-2060 v401 aLyons, Berry1 aWelch, Kathleen, A.1 aCarey, Anne, E.1 aWall, Diana, H.1 aVirginia, Ross, A.1 aFountain, Andrew, G1 aDoran, Peter, T.1 aCsatho, B1 aTremper, C uhttps://mcm.lternet.edu/content/groundwater-seeps-taylor-valley-antarctica-example-subsurface-melt-event00681nas a2200181 4500008004100000245012100041210006900162300001200231490000700243100001700250700002400267700001400291700001400305700001400319700001900333700002300352856012400375 2005 eng d00aHalogen geochemistry of the McMurdo Dry Valleys Lakes, Antarctica: clues to the origin of solutes and lake evolution0 aHalogen geochemistry of the McMurdo Dry Valleys Lakes Antarctica a305-3230 v691 aLyons, Berry1 aWelch, Kathleen, A.1 aSnyder, G1 aOlesik, J1 aGraham, E1 aMarion, G., M.1 aPoreda, Robert, J. uhttps://mcm.lternet.edu/content/halogen-geochemistry-mcmurdo-dry-valleys-lakes-antarctica-clues-origin-solutes-and-lake00476nas a2200133 4500008004100000245006400041210006400105300001000169490000700179100002000186700002000206700002300226856009300249 2005 eng d00aInvertebrate diversity in Taylor Valley soils and sediments0 aInvertebrate diversity in Taylor Valley soils and sediments a13-160 v331 aTreonis, Amy, M1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/invertebrate-diversity-taylor-valley-soils-and-sediments00509nas a2200121 4500008004100000245009200041210006900133260003000202490000900232100001600241700001700257856011300274 2005 eng d00aMercury Concentrations in Snow and the Modern Mercury Flux to Taylor Valley, Antarctica0 aMercury Concentrations in Snow and the Modern Mercury Flux to Ta bThe Ohio State University0 vM.S.1 aWitherow, R1 aLyons, Berry uhttps://mcm.lternet.edu/content/mercury-concentrations-snow-and-modern-mercury-flux-taylor-valley-antarctica00755nas a2200217 4500008004100000245008700041210006900128260003100197300001000228100002100238700002200259700002000281700002700301700001900328700002000347700002000367700002200387700001900409700001700428856009200445 2005 eng d00aPerennial Antarctic lake ice: A refuge for cyanobacteria in an extreme environment0 aPerennial Antarctic lake ice A refuge for cyanobacteria in an ex bPrinceton University Press a22-491 aPriscu, John, C.1 aAdams, Edward, E.1 aPaerl, Hans, W.1 aFritsen, Christian, H.1 aDore, John, E.1 aLisle, John, T.1 aWolf, Craig, F.1 aMikucki, Jill, A.1 aRogers, S., O.1 aCastello, J. uhttp://www.montana.edu/lkbonney/DOCS/Publications/PriscuEtAl2005CyanobacteriaRefuge.pdf00677nas a2200181 4500008004100000245009700041210006900138300001000207490000600217100002000223700002400243700002700267700001700294700002100311700001600332700002400348856012300372 2005 eng d00aPerturbation of hydrochemical conditions in natural microcosms entombed within Antarctic ice0 aPerturbation of hydrochemical conditions in natural microcosms e a22-230 v61 aTranter, Martyn1 aFountain, Andrew, G1 aFritsen, Christian, H.1 aLyons, Berry1 aPriscu, John, C.1 aStratham, P1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/perturbation-hydrochemical-conditions-natural-microcosms-entombed-within-antarctic-ice00875nas a2200361 4500008004100000245001800041210001800059260001700077300001200094100001900106700001500125700001500140700002300155700001300178700001300191700001900204700001500223700001400238700002000252700001500272700001400287700001700301700001800318700001900336700001400355700002200369700001400391700001500405700001500420700001600435700001200451856005000463 2005 eng d00aPolar Systems0 aPolar Systems bIsland Press a717-7431 aChapin, F., S.1 aMcGuire, A1 aNuttall, M1 aVirginia, Ross, A.1 aYoung, O1 aZimov, S1 aChristensen, T1 aGodduhn, A1 aMurphy, E1 aWall, Diana, H.1 aZockler, C1 aBerman, M1 aCallaghan, T1 aConvey, Peter1 aCrepin, A., S.1 aDanell, K1 aDucklow, Hugh, W.1 aForbes, B1 aKofinas, G1 aHassan, R.1 aScholes, R.1 aAsh, N. uhttps://mcm.lternet.edu/content/polar-systems02635nas a2200181 4500008004100000245007200041210006900113260001200182300001200194490000700206520208100213653001102294100002202305700002302327700002402350700002002374856005902394 2005 eng d00aPotential soil organic matter turnover in Taylor Valley, Antarctica0 aPotential soil organic matter turnover in Taylor Valley Antarcti c02/2005 a108-1170 v373 a

Antarctic Dry Valley ecosystems are among the most inhospitable soil ecosystems on earth with simple food webs and nearly undetectable fluxes of carbon (C) and nitrogen (N). Due to the lack of vascular plants, soil organic matter concentrations are extremely low, and it is unclear how much of the contemporary soil C budget is actively cycling or a legacy of paleolake production and sedimentation. While recent work indicates multiple sources of organic matter for dry valley soils, the composition and kinetics of organic pools remain poorly characterized. We examined soil organic matter pools and potential C and N turnover in soils from within six sites located across three hydrological basins of Taylor Valley, Antarctica that differed in surface age, microclimate and proximity to legacy (paleolake) sources of organic matter. We estimated potential C and N mineralization, and rate kinetics using gas exchange and repeated leaching techniques during 90-d incubations of surface soils collected from valley basin and valley slope positions in three basins of Taylor Valley. Soil organic C content was negatively correlated with the ages of underlying tills, supporting previous descriptions of legacy organic matter. Carbon and N mineralization generally followed 1st order kinetics and were well described by exponential models. Labile pools of C (90 d) were 10% of the total organic C in the upper 5 cm of the soil profile. Labile N was 50% of the total N in surface soils of Taylor Valley. These results show that a large proportion of soil C and particularly N are mineralizable under suitable conditions and suggest that a kinetically defined labile pool of organic matter is potentially active in the field during brief intervals of favorable microclimate. Climate variation changing the duration of these conditions may have potentially large effects on the small pools of C and N in these soils.

10aBiggie1 aBarrett, John, E.1 aVirginia, Ross, A.1 aParsons, Andrew, N.1 aWall, Diana, H. uhttp://instaar.metapress.com/content/e653225425230175/00648nas a2200181 4500008004100000245008700041210006900128300001200197490000800209100002000217700001800237700002900255700001400284700002200298700001600320700002100336856010900357 2005 eng d00aSoils, freshwater and marine sediments: the need for integrative landscape science0 aSoils freshwater and marine sediments the need for integrative l a302-3070 v3041 aWall, Diana, H.1 aAyres, Edward1 aBehan-Pelletier, Valerie1 aCovich, A1 aSnelgrove, P.V.R.1 aBrowman, H.1 aStergiou, K., I. uhttps://mcm.lternet.edu/content/soils-freshwater-and-marine-sediments-need-integrative-landscape-science00655nas a2200169 4500008004100000245010600041210006900147300001000216490000700226100001800233700002400251700002200275700002000297700002300317700002000340856012500360 2004 eng d00aThe Biodiversity and Biogeochemistry of Cryoconite Holes from McMurdo Dry Valley Glaciers, Antarctica0 aBiodiversity and Biogeochemistry of Cryoconite Holes from McMurd a84-910 v361 aPorazinska, D1 aFountain, Andrew, G1 aNylen, Thomas, H.1 aTranter, Martyn1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/biodiversity-and-biogeochemistry-cryoconite-holes-mcmurdo-dry-valley-glaciers-antarctica00642nas a2200145 4500008004100000245014700041210006900188490000700257100001900264700001700283700002100300700002500321700002400346856012600370 2004 eng d00aThe Carbon Isotopic Composition of Dissolved Inorganic Carbon in Perennially Ice-Covered Antarctica Lakes: Searching for a Biogenic Signature.0 aCarbon Isotopic Composition of Dissolved Inorganic Carbon in Per0 v391 aNeumann, Klaus1 aLyons, Berry1 aPriscu, John, C.1 aDesMarais, David, J.1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/carbon-isotopic-composition-dissolved-inorganic-carbon-perennially-ice-covered-antarctica00811nas a2200301 4500008004100000245004900041210004700090300001200137490000600149100001300155700001300168700001900181700001700200700001200217700001200229700001200241700002300253700002000276700001400296700002300310700002500333700001200358700001500370700001500385700001400400700001600414856007900430 2004 eng d00aDetritus, trophic dynamics and biodiversity.0 aDetritus trophic dynamics and biodiversity a584-6000 v71 aMoore, J1 aMorin, P1 aNadelhoffer, K1 aRosemound, A1 aPost, D1 aSabo, J1 aScow, K1 aVanni, Michael, J.1 aWall, Diana, H.1 aBerlow, E1 aColeman, David, C.1 aDe Ruiter, Peter, C.1 aDong, Q1 aHasting, A1 aJohnson, N1 aMcCann, K1 aMelville, K uhttps://mcm.lternet.edu/content/detritus-trophic-dynamics-and-biodiversity00670nas a2200157 4500008004100000245014600041210006900187300001200256490000700268100002300275700002100298700002000319700001700339700002800356856012800384 2004 eng d00aThe distribution of microplankton in the McMurdo dry valley lakes, Antarctica: Response to ecosystem legacy or present-day climate controls?0 adistribution of microplankton in the McMurdo dry valley lakes An a238-2490 v271 aRoberts, Emily, C.1 aPriscu, John, C.1 aWolf, Craig, F.1 aLyons, Berry1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/distribution-microplankton-mcmurdo-dry-valley-lakes-antarctica-response-ecosystem-legacy-or00578nas a2200169 4500008004100000245006700041210006600108300001400174490000800188100001400196700002600210700001800236700001400254700002200268700002000290856009800310 2004 eng d00aEcological linkages between aboveground and belowground biota.0 aEcological linkages between aboveground and belowground biota a1629-16330 v3041 aWardle, D1 aBardgett, Richard, D.1 aKlironomos, J1 aSetala, H1 avan der Putten, W1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/ecological-linkages-between-aboveground-and-belowground-biota00667nas 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-ice00594nas a2200193 4500008004100000245005000041210005000091260003100141100001200172700001400184700001300198700001400211700002100225700001600246700001500262700002900277700001500306856007900321 2004 eng d00aGeochronology of high latitude lake sediments0 aGeochronology of high latitude lake sediments bKluwer Academic Publishers1 aWolf, A1 aMiller, G1 aOlsen, C1 aForman, S1 aDoran, Peter, T.1 aHolmgren, S1 aPienitz, R1 aDouglas, Marianne, S. V.1 aSmol, J.P. uhttps://mcm.lternet.edu/content/geochronology-high-latitude-lake-sediments00555nas a2200121 4500008004100000245014000041210006900181300001200250490000700262100001400269700002400283856012600307 2004 eng d00aThe impact of anhydrobiosis on the persistence of Scottnema lindsyae (Nematoda): a modeling analysis of population stability thresholds0 aimpact of anhydrobiosis on the persistence of Scottnema lindsyae a507-5120 v271 aWeicht, T1 aMoorhead, Daryl, L. uhttps://mcm.lternet.edu/content/impact-anhydrobiosis-persistence-scottnema-lindsyae-nematoda-modeling-analysis-population00616nas a2200169 4500008004100000245014100041210006900182260001200251300001200263490000700275653002100282653001800303100002700321700001200348700002100360856006500381 2004 eng d00aImpact of episodic warming events on the physical, chemical and biological relationships of lakes in the McMurdo Dry Valleys, Antarctica0 aImpact of episodic warming events on the physical chemical and b c09/2004 a239-2680 v1010aClimate Response10astoichiometry1 aForeman, Christine, M.1 aWolf, C1 aPriscu, John, C. uhttp://link.springer.com/article/10.1007%2Fs10498-004-2261-300626nas a2200145 4500008004100000245012200041210006900163260001700232100002000249700002600269700001400295700002200309700002000331856012900351 2004 eng d00aThe need for understanding how biodiversity and ecosystem functioning affect ecosystem services in soil and sediments0 aneed for understanding how biodiversity and ecosystem functionin bIsland Press1 aWall, Diana, H.1 aBardgett, Richard, D.1 aCovich, A1 aSnelgrove, P.V.R.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/need-understanding-how-biodiversity-and-ecosystem-functioning-affect-ecosystem-services-soil00504nas a2200145 4500008004100000245006100041210006100102300001200163490000600175100002400181700002200205700002000227700002300247856008800270 2004 eng d00aSoil carbon dioxide flux from Antarctic Dry Valley soils0 aSoil carbon dioxide flux from Antarctic Dry Valley soils a286-2950 v71 aParsons, Andrew, N.1 aBarrett, John, E.1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/soil-carbon-dioxide-flux-antarctic-dry-valley-soils00424nam a2200097 4500008004100000245007400041210006900115100002000184700002000204856010200224 2004 eng d00aSustaining Biodiversity and Ecosystem Services in Soil and Sediments.0 aSustaining Biodiversity and Ecosystem Services in Soil and Sedim1 aWall, Diana, H.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/sustaining-biodiversity-and-ecosystem-services-soil-and-sediments00726nas a2200205 4500008004100000245011200041210006900153300000900222490000700231100001100238700002200249700002700271700002100298700001900319700001500338700001400353700002000367700001400387856011900401 2004 eng d00aThermodynamic constraints on microbially mediated processes in lakes of the McMurdo Dry Valleys, Antarctica0 aThermodynamic constraints on microbially mediated processes in l a1-170 v211 aLee, P1 aMikucki, Jill, A.1 aForeman, Christine, M.1 aPriscu, John, C.1 aDiTullio, G, R1 aRiseman, S1 aDeMora, S1 aWolf, Craig, F.1 aKester, L uhttps://mcm.lternet.edu/content/thermodynamic-constraints-microbially-mediated-processes-lakes-mcmurdo-dry-valleys00681nas a2200205 4500008004100000245009300041210006900134300001200203490000600215100001600221700001700237700001500254700001500269700001300284700001200297700001400309700001300323700002000336856011900356 2004 eng d00aTrophic interactions in a changing world: modelling aboveground-belowground interactions0 aTrophic interactions in a changing world modelling abovegroundbe a515-5280 v51 aSchroter, D1 aBrussaard, L1 aDe Deyn, G1 aProveda, K1 aBrown, V1 aBerg, M1 aWardle, D1 aMoore, J1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/trophic-interactions-changing-world-modelling-aboveground-belowground-interactions00662nas a2200157 4500008004100000245014000041210006900181260001700250300001200267100002000279700002600299700001400325700002200339700002000361856012300381 2004 eng d00aUnderstanding the functions of biodiversity in soils and sediments will enhance global ecosystem sustainability and societal well-being0 aUnderstanding the functions of biodiversity in soils and sedimen bIsland Press a249-2541 aWall, Diana, H.1 aBardgett, Richard, D.1 aCovich, A1 aSnelgrove, P.V.R.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/understanding-functions-biodiversity-soils-and-sediments-will-enhance-global-ecosystem02593nas a2200181 4500008004100000245009500041210006900136300001400205490000700219520193100226100002202157700002302179700002002202700002402222700002202246700002402268856011902292 2004 eng d00aVariation in biogeochemistry and soil biodiversity across spatial scales in a polar desert0 aVariation in biogeochemistry and soil biodiversity across spatia a3105-31180 v853 a
Desert ecosystems are characterized by distinct spatial patterning in soil
biogeochemistry and biodiversity. In the Antarctic Dry Valleys, soil polygons are prominent
features of the landscape and may be key units for scaling local ecological information to
the greater region. We examined polygon soils in each of the three basins of Taylor Valley,
Antarctica. Our objectives were to characterize variability in soil biogeochemistry and
biodiversity at local to regional scales, and to test the influence of soil properties upon
invertebrate communities. We found that soil biogeochemical properties and biodiversity
vary over multiple spatial scales from fine (,10 m) to broad (.10 km) scales. Differences
in biogeochemistry were most pronounced at broad scales among the major lake basins of
Taylor Valley corresponding to differences in geology and microclimate, while variation
in invertebrate biodiversity and abundance occurred at landscape scales of 10–500 m, and
within individual soil polygons. Variation in biogeochemistry and invertebrate communities
across these scales reflects the influence of physical processes and landscape development
over ecosystem structure in the dry valleys. The development of soil polygons influences
the spatial patterning of soil properties such as soil organic matter, salinity, moisture, and
invertebrate habitat suitability. Nematode abundance and life history data indicate that
polygon interiors are more suitable habitats than soils in the troughs at the edges of polygons.
These data suggest that physical processes (i.e., polygon development) and biogeochemistry
are important influences on the spatial variability of biotic communities in dry valley soil
ecosystems.
1 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aParsons, Andrew, N.1 aPowers, Laura, E.1 aBurkins, Melody, B. uhttps://mcm.lternet.edu/content/variation-biogeochemistry-and-soil-biodiversity-across-spatial-scales-polar-desert00957nas a2200301 4500008004100000020001800041245008800059210006900147260001700216300001200233100001400245700001600259700002900275700001400304700001700318700002600335700001800361700001500379700001500394700002200409700002100431700001700452700001800469700001700487700002000504700002000524856011100544 2004 eng d a1-55963-760-900aVulnerability to global change of ecosystem goods and services driven by soil biota0 aVulnerability to global change of ecosystem goods and services d bIsland Press a101-1361 aWardle, D1 aBrown, V.K.1 aBehan-Pelletier, Valerie1 aJohn, St.1 aWojtowicz, T1 aBardgett, Richard, D.1 aBrown, G., G.1 aIneson, P.1 aLavelle, P1 avan der Putten, W1 aAnderson, J., M.1 aBrussaard, L1 aHunt, William1 aPaul, E., A.1 aWall, Diana, H.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/vulnerability-global-change-ecosystem-goods-and-services-driven-soil-biota00536nas a2200157 4500008004100000245006700041210006600108300001200174490000600186100001200192700002400204700001700228700002100245700002400266856008800290 2003 eng d00aBiochemistry of Si in the McMurdo Dry Valley lakes, Antarctica0 aBiochemistry of Si in the McMurdo Dry Valley lakes Antarctica a737-7490 v11 aPugh, H1 aWelch, Kathleen, A.1 aLyons, Berry1 aPriscu, John, C.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/biochemistry-si-mcmurdo-dry-valley-lakes-antarctica00679nas a2200169 4500008004100000245011200041210006900153260001700222100002400239700001900263700001700282700002400299700002700323700001700350700001500367856012700382 2003 eng d00aChemistry and lake dynamics of the Taylor Valley lakes, Antarctica: The importance of long-term monitoring.0 aChemistry and lake dynamics of the Taylor Valley lakes Antarctic bCaxton Press1 aWelch, Kathleen, A.1 aNeumann, Klaus1 aLyons, Berry1 aMcKnight, Diane, M.1 aHoward-Williams, Clive1 aDavidson, W.1 aBroady, P. uhttps://mcm.lternet.edu/content/chemistry-and-lake-dynamics-taylor-valley-lakes-antarctica-importance-long-term-monitoring00733nas a2200193 4500008004100000245014900041210006900190300001200259490000600271100001500277700002100292700001900313700001400332700001400346700001900360700001500379700002100394856012400415 2003 eng d00aFourier-transform raman spectroscopic studies of organic and inorganic chemical components in stromatolitic cores from Antarctic lake sediments0 aFouriertransform raman spectroscopic studies of organic and inor a325-3310 v11 aEdwards, H1 aWynn-Williams, D1 aEllis-Evans, J1 aNewton, E1 aLittle, S1 ade Oliveira, L1 aHodgson, D1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/fourier-transform-raman-spectroscopic-studies-organic-and-inorganic-chemical-components00584nas a2200181 4500008004100000245006300041210006000104300001000164100001500174700001600189700002000205700001300225700001600238700001800254700002500272700001400297856009100311 2003 eng d00aLong-term perspectives on biodiversity-ecosystem function.0 aLongterm perspectives on biodiversityecosystem function a89-981 aSymstad, A1 aIII, Chapin1 aWall, Diana, H.1 aGross, K1 aHuenneke, L1 aMittelbach, G1 aPeters, Debra, P. C.1 aTilman, D uhttps://mcm.lternet.edu/content/long-term-perspectives-biodiversity-ecosystem-function00585nas a2200157 4500008004100000245008200041210006900123300001400192490000700206100002400213700002200237700002300259700002000282700001800302856010700320 2003 eng d00aOrganic matter and soil biota of upland wetlands in Taylor Valley, Antarctica0 aOrganic matter and soil biota of upland wetlands in Taylor Valle a1009-10190 v261 aMoorhead, Daryl, L.1 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aPorazinska, D uhttps://mcm.lternet.edu/content/organic-matter-and-soil-biota-upland-wetlands-taylor-valley-antarctica00722nas a2200193 4500008004100000245015200041210006900193300001200262490000600274100001700280700001800297700001400315700001400329700001400343700001200357700002400369700001400393856012100407 2003 eng d00aStrontium isotopic signatures of the streams and lakes of Taylor Valley, southern Victoria Land, Antarctica: chemical weathering in a polar climate0 aStrontium isotopic signatures of the streams and lakes of Taylor a875-8950 v81 aLyons, Berry1 aNezat, C., A.1 aBenson, L1 aBullen, T1 aGraham, E1 aKidd, J1 aWelch, Kathleen, A.1 aThomas, J uhttps://mcm.lternet.edu/content/strontium-isotopic-signatures-streams-and-lakes-taylor-valley-southern-victoria-land00682nas a2200169 4500008004100000245012300041210006900164300001200233490000700245100001700252700002400269700002400293700002000317700002200337700002400359856012900383 2003 eng d00aSurface glaciochemistry of Taylor Valley, southern Victoria Land, Antarctica and its relationship to stream chemistry.0 aSurface glaciochemistry of Taylor Valley southern Victoria Land  a115-1300 v171 aLyons, Berry1 aWelch, Kathleen, A.1 aFountain, Andrew, G1 aDana, Gayle, L.1 aVaughn, Bruce, H.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/surface-glaciochemistry-taylor-valley-southern-victoria-land-antarctica-and-its-relationship00890nas a2200277 4500008004100000245006500041210006500106260001200171300001200183490000800195653002100203100002100224700002100245700001700266700002000283700002400303700002400327700002400351700002300375700002000398700001900418700002700437700002700464700002400491856009700515 2002 eng d00aAntarctic climate cooling and terrestrial ecosystem response0 aAntarctic climate cooling and terrestrial ecosystem response c01/2002 a517-5200 v41510aClimate Response1 aDoran, Peter, T.1 aPriscu, John, C.1 aLyons, Berry1 aWalsh, John, E.1 aFountain, Andrew, G1 aMcKnight, Diane, M.1 aMoorhead, Daryl, L.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aClow, Gary, D.1 aFritsen, Christian, H.1 aMcKay, Christopher, P.1 aParsons, Andrew, N. uhttps://mcm.lternet.edu/content/antarctic-climate-cooling-and-terrestrial-ecosystem-response00625nas a2200145 4500008004100000245013200041210006900173300001200242490000700254100002400261700002000285700002300305700002400328856012700352 2002 eng d00aDistribution and life cycle of Scottnema lindsayae (Nematoda) in Antarctic soils: A modeling analysis of tempaerature responses0 aDistribution and life cycle of Scottnema lindsayae Nematoda in A a118-1250 v251 aMoorhead, Daryl, L.1 aWall, Diana, H.1 aVirginia, Ross, A.1 aParsons, Andrew, N. uhttps://mcm.lternet.edu/content/distribution-and-life-cycle-scottnema-lindsayae-nematoda-antarctic-soils-modeling-analysis00548nas a2200169 4500008004100000245005100041210005000092260004700142300001200189100001500201700001300216700002100229700001700250700001400267700001500281856008200296 2002 eng d00aExtremophiles: ice ecosystems and biodiversity0 aExtremophiles ice ecosystems and biodiversity aOxfordbUNESCO Publishing-Eolss Publishers a573-5981 aPsenner, R1 aFelip, M1 aPriscu, John, C.1 aWagenbach, D1 aWillie, A1 aSattler, B uhttps://mcm.lternet.edu/content/extremophiles-ice-ecosystems-and-biodiversity00499nas a2200121 4500008004100000245008700041210006900128490000600197100002000203700002000223700002300243856011100266 2002 eng d00aField and microcosm studies of decomposition and soil biota in a cold dessert soil0 aField and microcosm studies of decomposition and soil biota in a0 v51 aTreonis, Amy, M1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/field-and-microcosm-studies-decomposition-and-soil-biota-cold-dessert-soil00481nas a2200133 4500008004100000245006800041210006600109300001200175490000700187100001800194700002000212700002300232856009200255 2002 eng d00aInvertebrates in ornithogenic soils at Ross Island, Antarctica.0 aInvertebrates in ornithogenic soils at Ross Island Antarctica a569-5740 v251 aPorazinska, D1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/invertebrates-ornithogenic-soils-ross-island-antarctica00452nas a2200121 4500008004100000245007700041210006900118300001000187490000600197100001200203700002000215856009500235 2002 eng d00aModeling the effects of loss of soil biodiversity on ecosystem function0 aModeling the effects of loss of soil biodiversity on ecosystem f a32-490 v81 aHunt, H1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/modeling-effects-loss-soil-biodiversity-ecosystem-function00578nas a2200133 4500008004100000245012500041210006900166300001200235490000700247100001800254700002000272700002300292856012900315 2002 eng d00aPopulation age structure of nematodes in the Antarctic Dry Valleys: perspectives on time, space, and habitat suitability0 aPopulation age structure of nematodes in the Antarctic Dry Valle a159-1680 v341 aPorazinska, D1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/population-age-structure-nematodes-antarctic-dry-valleys-perspectives-time-space-and-habitat00772nas a2200253 4500008004100000245004700041210004700088300001200135490000800147100002000155700001900175700002700194700002700221700002400248700002100272700002100293700001700314700002400331700002400355700002400379700002300403700002000426856007200446 2002 eng d00aRecent Temperature Trends in the Antarctic0 aRecent Temperature Trends in the Antarctic a291-2920 v4181 aWalsh, John, E.1 aClow, Gary, D.1 aFritsen, Christian, H.1 aMcKay, Christopher, P.1 aParsons, Andrew, N.1 aDoran, Peter, T.1 aPriscu, John, C.1 aLyons, Berry1 aFountain, Andrew, G1 aMcKnight, Diane, M.1 aMoorhead, Daryl, L.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/recent-temperature-trends-antarctic00540nas a2200145 4500008004100000245007900041210006900120300001400189490000700203100002000210700001300230700002400243700002400267856010300291 2002 eng d00aSatellite-Derived Indices of Stream Discharge in Taylor Valley,Antarctica.0 aSatelliteDerived Indices of Stream Discharge in Taylor ValleyAnt a1603-16160 v161 aDana, Gayle, L.1 aDavis, R1 aFountain, Andrew, G1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/satellite-derived-indices-stream-discharge-taylor-valleyantarctica00760nas a2200229 4500008004100000245012700041210006900168260001200237300001000249490000700259653001100266100002500277700002200302700002100324700002400345700001700369700002400386700001800410700002300428700002000451856005900471 2002 eng d00aSnow patch influence on soil biogeochemical processes and invertebrate distribution in the McMurdo Dry Valleys, Antarctica0 aSnow patch influence on soil biogeochemical processes and invert c02/2003 a91-990 v3510aBiggie1 aGooseff, Michael, N.1 aBarrett, John, E.1 aDoran, Peter, T.1 aFountain, Andrew, G1 aLyons, Berry1 aParsons, Andrew, N.1 aPorazinska, D1 aVirginia, Ross, A.1 aWall, Diana, H. uhttp://instaar.metapress.com/content/r086455ju7213711/00561nas a2200133 4500008004100000245011000041210006900151300001200220490000600232100002200238700002300260700002000283856012400303 2002 eng d00aTrends in resin and KCl-extractable soil nitrogen across landscape gradients in Taylor Valley, Antarctica0 aTrends in resin and KClextractable soil nitrogen across landscap a289-2990 v51 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/trends-resin-and-kcl-extractable-soil-nitrogen-across-landscape-gradients-taylor-valley00446nas a2200145 4500008004100000245005100041210005000092300001200142490000600154100001200160700002000172700001700192700001500209856007600224 2001 eng d00a519-529A model for nematode locomotion in soil0 a519529A model for nematode locomotion in soil a705-7160 v31 aHunt, H1 aWall, Diana, H.1 aDeCrappeo, N1 aBrenner, J uhttps://mcm.lternet.edu/content/519-529a-model-nematode-locomotion-soil00448nas a2200145 4500008004100000245004600041210004600087260001900133300001200152490000600164100002300170700002000193700001400213856007500227 2001 eng d00aBasic Principles in ecosystem functioning0 aBasic Principles in ecosystem functioning bAcademic Press a345-3520 v21 aVirginia, Ross, A.1 aWall, Diana, H.1 aLevin, S. uhttps://mcm.lternet.edu/content/basic-principles-ecosystem-functioning00607nas a2200133 4500008004100000245015900041210006900200300001200269490000600281100002000287700001700307700002200324856012700346 2001 eng d00aBiodiversity in critical transition zones between terrestrial freshwater and marine soils and sediments: processes, linkages, and management implications.0 aBiodiversity in critical transition zones between terrestrial fr a418-4200 v41 aWall, Diana, H.1 aPalmer, M.A.1 aSnelgrove, P.V.R. uhttps://mcm.lternet.edu/content/biodiversity-critical-transition-zones-between-terrestrial-freshwater-and-marine-soils-and00510nas a2200133 4500008004100000245008300041210006900124300001400193490000800207100001800215700001700233700002400250856010200274 2001 eng d00aChemical weathering in streams of a polar desert (Taylor Valley, Antarctica).0 aChemical weathering in streams of a polar desert Taylor Valley A a1401-14080 v1131 aNezat, C., A.1 aLyons, Berry1 aWelch, Kathleen, A. 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C.1 aFelip, M1 aCatalan, J. uhttps://mcm.lternet.edu/content/lake-ice-microbial-communities-alpine-and-antarctic-lakes00514nas a2200109 4500008004100000245006200041210006000103260010700163100002400270700002100294856008900315 1999 eng d00aMcMurdo Dry Valley Lakes: Impacts of Research Activities.0 aMcMurdo Dry Valley Lakes Impacts of Research Activities bDesert Research Institute, University and Community College System of Nevada, USA, special publication1 aWharton, Robert, A.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/mcmurdo-dry-valley-lakes-impacts-research-activities00424nas a2200133 4500008004100000245004500041210004500086300001400131490000700145100001700152700002400169700002600193856007100219 1999 eng d00aMercury in aquatic systems in Antarctica0 aMercury in aquatic systems in Antarctica a2235-22380 v261 aLyons, Berry1 aWelch, Kathleen, A.1 aBonzongo, Jean-Claude uhttps://mcm.lternet.edu/content/mercury-aquatic-systems-antarctica00878nas a2200277 4500008004100000245006500041210006400106260001200170300001200182490000700194653002300201100002400224700001700248700002400265700002000289700002100309700002100330700002400351700002400375700002400399700002100423700002000444700002400464700002300488856008900511 1999 eng d00aPhysical controls on the Taylor Valley Ecosystem, Antarctica0 aPhysical controls on the Taylor Valley Ecosystem Antarctica c12/1999 a961-9720 v4910aWater availability1 aFountain, Andrew, G1 aLyons, Berry1 aBurkins, Melody, B.1 aDana, Gayle, L.1 aDoran, Peter, T.1 aLewis, Karen, J.1 aMcKnight, Diane, M.1 aMoorhead, Daryl, L.1 aParsons, Andrew, N.1 aPriscu, John, C.1 aWall, Diana, H.1 aWharton, Robert, A.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/physical-controls-taylor-valley-ecosystem-antarctica00404nas a2200133 4500008004100000245003600041210003500077260003000112300001200142100002000154700001700174700001500191856006400206 1999 eng d00aSoil Biodiversity: life in soil0 aSoil Biodiversity life in soil bColumbia University Press a124-1281 aWall, Diana, H.1 aCracraft, J.1 aGriffo, F. uhttps://mcm.lternet.edu/content/soil-biodiversity-life-soil00536nas a2200193 4500008004100000245002300041210002300064260003800087300001200125100002300137700001600160700001400176700002000190700002000210700001800230700002300248700001600271856005500287 1999 eng d00aSoil invertebrates0 aSoil invertebrates aNew YorkbOxford University Press a349-3771 aColeman, David, C.1 aBlair, J.M.1 aElliot, E1 aWall, Diana, H.1 aRobertson, G.P.1 aBledsoe, C.S.1 aColeman, David, C.1 aSollins, P. uhttps://mcm.lternet.edu/content/soil-invertebrates00546nas a2200133 4500008004100000245007600041210006900117260003900186100002000225700002300245700002000268700002100288856010300309 1999 eng d00aThe world beneath our feet: Soil biodiversity and ecosystem functioning0 aworld beneath our feet Soil biodiversity and ecosystem functioni bNational Academy of Sciences Press1 aWall, Diana, H.1 aVirginia, Ross, A.1 aWilliams, Tania1 aRaven, 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4500008004100000245009600041210006900137300001200206490000700218100001700225700002100242700002400263700002400287700002200311856012100333 1998 eng d00aA late holocene dessication of Lake Hoare and Lake Fryxell, McMurdo Dry Valleys, Antarctica0 alate holocene dessication of Lake Hoare and Lake Fryxell McMurdo a247-2560 v101 aLyons, Berry1 aTyler, Scott, W.1 aWharton, Robert, A.1 aMcKnight, Diane, M.1 aVaughn, Bruce, H. uhttps://mcm.lternet.edu/content/late-holocene-dessication-lake-hoare-and-lake-fryxell-mcmurdo-dry-valleys-antarctica00531nas a2200121 4500008004100000245010700041210006900148300001200217490000700229100003000236700002400266856011900290 1998 eng d00aMcMurdo Dry Valleys Long-Term Ecological Research (LTER): An overview of 1995-1996 research activities0 aMcMurdo Dry Valleys LongTerm Ecological Research LTER An overvie a187-1880 v311 aJennings-Mays, Sherry, E.1 aWharton, Robert, A. 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aGranger, R.1 aPultz, T.J. uhttps://mcm.lternet.edu/content/temperature-area-index-stream-discharge-taylor-valley-antarctica00397nas a2200145 4500008004100000245003100041210003100072300001400103490000700117653001100124100001700135700002400152700001500176856006000191 1998 eng d00aViruses in antarctic lakes0 aViruses in antarctic lakes a1754-17610 v4310aBiggie1 aKepner, R.L.1 aWharton, Robert, A.1 aSuttle, C. uhttps://mcm.lternet.edu/content/viruses-antarctic-lakes00597nas a2200169 4500008004100000245007200041210006700113260002900180300001200209100001700221700002400238700001700262700001700279700002700296700001500323856008900338 1997 eng d00aThe abundance of planktonic virus-like particles in Antarctic lakes0 aabundance of planktonic viruslike particles in Antarctic lakes aRotterdambBalkema Press a241-2501 aKepner, R.L.1 aWharton, Robert, A.1 aGalchenko, V1 aLyons, Berry1 aHoward-Williams, Clive1 aHawes, Ian 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Comparison to temperate river basins0 aChemical weathering rates and reactions in the Lake Fryxell Basi bBalkema Press, Rotterdam a147-1541 aLyons, Berry1 aWelch, Kathleen, A.1 aNezat, C., A.1 aCrick, K.1 aToxey, Jeffrey, K.1 aMastrine, J.A.1 aMcKnight, Diane, M.1 aLyons, Berry1 aHoward-Williams, Clive1 aHawes, Ian uhttps://mcm.lternet.edu/content/chemical-weathering-rates-and-reactions-lake-fryxell-basin-taylor-valley-comparison00524nas a2200121 4500008004100000245010600041210006900147300001000216490000800226100001900234700002100253856012800274 1997 eng d00aDetection and Characterization of Denitrifying Bacteria from a Permanently Ice-Covered Antarctic Lake0 aDetection and Characterization of Denitrifying Bacteria from a P a57-680 v3471 aWard, Bess, B.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/detection-and-characterization-denitrifying-bacteria-permanently-ice-covered-antarctic-lake00602nas a2200145 4500008004100000245009900041210006900140260003900209300001200248100001400260700001900274700001700293700002400310856012200334 1997 eng d00aDetermination of rare earth elements in Antarctic lakes and streams of varying ionic strengths0 aDetermination of rare earth elements in Antarctic lakes and stre aLondonbRoyal Society of Chemistry a253-2621 aGraham, E1 aRamsey, L., A.1 aLyons, Berry1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/determination-rare-earth-elements-antarctic-lakes-and-streams-varying-ionic-strengths00801nas a2200217 4500008004100000245015200041210006900193260002700262300001100289490000700300100002500307700002400332700002500356700002000381700002100401700002400422700002000446700002400466700001600490856007700506 1997 eng d00aEcological processes in a cold desert ecosystem: the abundance and species distribution of algal mats in glacial meltwater streams in Taylor Valley0 aEcological processes in a cold desert ecosystem the abundance an bUniversity of Colorado a108 pp0 v511 aAlger, Alexander, S.1 aMcKnight, Diane, M.1 aSpaulding, Sarah, A.1 aTate, Cathy, M.1 aShupe, Gordon, H1 aWelch, Kathleen, A.1 aEdwards, R., L.1 aAndrews, Edmund, D.1 aHouse, H.R. uhttp://instaar.colorado.edu/other/download/OP51-ECOLOGICAL-PROCESSES.pdf00578nas a2200133 4500008004100000245011900041210006900160300001400229490000700243100002400250700002000274700002400294856012600318 1997 eng d00aImpact of Light Regimes on Productivity Patterns of Benthic Microbial Mats in an Antarctic Lake: A Modeling Study0 aImpact of Light Regimes on Productivity Patterns of Benthic Micr a1561-15690 v421 aMoorhead, Daryl, L.1 aWolf, Craig, F.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/impact-light-regimes-productivity-patterns-benthic-microbial-mats-antarctic-lake-modeling00369nas a2200121 4500008004100000245004000041210004000081300001400121490000700135100001700142700002400159856006400183 1997 eng d00aLithium in waters of a polar desert0 aLithium in waters of a polar desert a4309-43190 v611 aLyons, Berry1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/lithium-waters-polar-desert00516nas a2200133 4500008004100000245008200041210006900123260001100192300001200203100002000215700001700235700002400252856010600276 1997 eng d00aSatellite-derived surface temperatures in the McMurdo Dry Valleys, Antarctica0 aSatellitederived surface temperatures in the McMurdo Dry Valleys bDeepak a530-5331 aDana, Gayle, L.1 aWetzel, M.A.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/satellite-derived-surface-temperatures-mcmurdo-dry-valleys-antarctica00555nas a2200121 4500008004100000245011700041210006900158260003000227490001000257100002000267700002000287856012600307 1996 eng d00aAlgal investigations at varying temporal scales in an extreme environment: McMurdo Dry Valley lakes, Antarctica0 aAlgal investigations at varying temporal scales in an extreme en bColorado State University0 vPh.D.1 aSpaulding, S.A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/algal-investigations-varying-temporal-scales-extreme-environment-mcmurdo-dry-valley-lakes00641nas a2200169 4500008004100000245010500041210006900146300001200215490000800227100002400235700001700259700001400276700001900290700002200309700001700331856012300348 1996 eng d00aDetermination of major element chemistry in terrestrial waters from Antarctica by ion chromatography0 aDetermination of major element chemistry in terrestrial waters f a257-2630 v7391 aWelch, Kathleen, A.1 aLyons, Berry1 aGraham, E1 aNeumann, Klaus1 aThomas, James, M.1 aMikesell, D. uhttps://mcm.lternet.edu/content/determination-major-element-chemistry-terrestrial-waters-antarctica-ion-chromatography00428nas a2200133 4500008004100000245004300041210004200084300001200126100001800138700001700156700002400173700002200197856007500219 1996 eng d00aFood-web dynamics and applied problems0 aFoodweb dynamics and applied problems a327-3361 aCrowder, L.B.1 aReagan, D.P.1 aFreckman, Diana, W.1 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uhttps://mcm.lternet.edu/content/lakes-hoare-fryxell-and-bonney-geophysical-determination-bathymetry-and-morphometry-report00487nas a2200121 4500008004100000245006700041210006600108260004000174490001000214100002100224700002400245856009600269 1996 eng d00aPaleolimnology of Perenially Ice-Covered Antarctic Oasis Lakes0 aPaleolimnology of Perenially IceCovered Antarctic Oasis Lakes aReno, NVbUniversity of Nevada Reno0 vPh.D.1 aDoran, Peter, T.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/paleolimnology-perenially-ice-covered-antarctic-oasis-lakes00741nas a2200193 4500008004100000245014600041210006900187300001200256490000700268100002300275700001500298700001500313700001600328700002000344700002300364700001800387700002400405856011800429 1996 eng d00aReflectance spectroscopy and geochemical analyses of Lake Hoare sediments, Antarctica: Implications for remote sensing of the Earth and Mars0 aReflectance spectroscopy and geochemical analyses of Lake Hoare  a765-7850 v601 aBishop, Janice, L.1 aKoeberl, C1 aKralik, C.1 aFroschl, H.1 aEnglert, P.A.J.1 aAndersen, Dale, T.1 aPieters, C.M.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/reflectance-spectroscopy-and-geochemical-analyses-lake-hoare-sediments-antarctica00529nas a2200121 4500008004100000245008600041210006900127260004800196490000900244100002600253700002000279856010800299 1996 eng d00aSoil nematode distribution and genetic diversity in the Dry Valleys of Antarctica0 aSoil nematode distribution and genetic diversity in the Dry Vall aFort Collins, CObColorado State University0 vM.S.1 aCourtright, Ericha, M1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/soil-nematode-distribution-and-genetic-diversity-dry-valleys-antarctica00486nas a2200133 4500008004100000245007300041210006900114300000800183490000700191100001700198700002400215700001700239856009600256 1996 eng d00aViruses in antarctic lakes: a first assessment of their distribution0 aViruses in antarctic lakes a first assessment of their distribut a2300 v771 aKepner, R.L.1 aWharton, Robert, A.1 aGalchenko, V uhttps://mcm.lternet.edu/content/viruses-antarctic-lakes-first-assessment-their-distribution00489nas a2200109 4500008004100000245010700041210006900148300001200217490000700229100002400236856011900260 1995 eng d00aMcMurdo Dry Valleys Long-Term Ecological Research (LTER): An overview of 1994-1995 research activities0 aMcMurdo Dry Valleys LongTerm Ecological Research LTER An overvie a275-2760 v301 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/mcmurdo-dry-valleys-long-term-ecological-research-lter-overview-1994-1995-research00596nas a2200145 4500008004100000245010000041210006900141300001200210490000700222100002100229700002000250700002900270700002400299856012700323 1995 eng d00aMcMurdo Dry Valleys Long-Term Ecological Research (LTER): LTER automatic weather network (LAWN)0 aMcMurdo Dry Valleys LongTerm Ecological Research LTER LTER autom a276-2800 v301 aDoran, Peter, T.1 aDana, Gayle, L.1 aHastings, Jordan, Towner1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/mcmurdo-dry-valleys-long-term-ecological-research-lter-lter-automatic-weather-network-lawn00483nas a2200121 4500008004100000245008600041210006900127300001200196490000700208100002400215700001700239856010500256 1995 eng d00aMcMurdo LTER: Comparative limnology of the Taylor Valley lakes: The major solutes0 aMcMurdo LTER Comparative limnology of the Taylor Valley lakes Th a292-2930 v301 aWelch, Kathleen, A.1 aLyons, Berry uhttps://mcm.lternet.edu/content/mcmurdo-lter-comparative-limnology-taylor-valley-lakes-major-solutes00383nas a2200145 4500008004100000245002300041210002300064300001200087490000700099100002400106700001500130700002700145700001300172856005200185 1995 eng d00aPaleolakes on Mars0 aPaleolakes on Mars a267-2830 v131 aWharton, Robert, A.1 aCrosby, J.1 aMcKay, Christopher, P.1 aRice, J. uhttps://mcm.lternet.edu/content/paleolakes-mars00600nas a2200157 4500008004100000245008800041210006900129260001200198300001600210490000700226100002700233700001900260700002300279700002400302856011600326 1994 eng d00aLight transmission and reflection in perennially ice-covered Lake Hoare, Antarctica0 aLight transmission and reflection in perennially icecovered Lake c06/1994 a20427-204440 v991 aMcKay, Christopher, P.1 aClow, Gary, D.1 aAndersen, Dale, T.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/light-transmission-and-reflection-perennially-ice-covered-lake-hoare-antarctica00439nas a2200109 4500008004100000245007600041210006900117300001200186490000700198100002400205856010000229 1994 eng d00aMcMurdo Dry Valleys LTER: An overview of 1993-1994 research activities0 aMcMurdo Dry Valleys LTER An overview of 19931994 research activi a224-2260 v291 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/mcmurdo-dry-valleys-lter-overview-1993-1994-research-activities00688nas a2200181 4500008004100000245010100041210006900142300001200211490000700223100002400230700001700254700002100271700002000292700002400312700002200336700002400358856012400382 1994 eng d00aMcMurdo LTER: Inorganic geochemical studies with special reference to calcium carbonate dynamics0 aMcMurdo LTER Inorganic geochemical studies with special referenc a237-2390 v291 aWelch, Kathleen, A.1 aLyons, Berry1 aPriscu, John, C.1 aEdwards, R., L.1 aMcKnight, Diane, M.1 aHouse, Harold, R.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/mcmurdo-lter-inorganic-geochemical-studies-special-reference-calcium-carbonate-dynamics00506nas a2200145 4500008004100000245006200041210006000103300001200163490000700175100002100182700002400203700002500227700001900252856008900271 1994 eng d00aMcMurdo LTER: Paleolimnology of Taylor Valley, Antarctica0 aMcMurdo LTER Paleolimnology of Taylor Valley Antarctica a234-2370 v291 aDoran, Peter, T.1 aWharton, Robert, A.1 aSpaulding, Sarah, A.1 aFoster, J., S. uhttps://mcm.lternet.edu/content/mcmurdo-lter-paleolimnology-taylor-valley-antarctica00513nas a2200121 4500008004100000245009500041210006900136300001200205490000700217100002400224700002400248856011900272 1994 eng d00aMcMurdo LTER: Primary production model of benthic microbial mats in Lake Hoare, Antarctica0 aMcMurdo LTER Primary production model of benthic microbial mats  a241-2430 v291 aMoorhead, Daryl, L.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/mcmurdo-lter-primary-production-model-benthic-microbial-mats-lake-hoare-antarctica00452nas a2200133 4500008004100000245005800041210005700099300001100156490000700167100002100174700002400195700001700219856008200236 1994 eng d00aPaleolimnology of the McMurdo Dry Valleys, Antarctica0 aPaleolimnology of the McMurdo Dry Valleys Antarctica a85-1140 v101 aDoran, Peter, T.1 aWharton, Robert, A.1 aLyons, Berry uhttps://mcm.lternet.edu/content/paleolimnology-mcmurdo-dry-valleys-antarctica00402nas a2200121 4500008004100000245004100041210004100082260002400123100002400147700002500171700001400196856007000210 1994 eng d00aStromatolite mats in Antarctic lakes0 aStromatolite mats in Antarctic lakes bKluwer, Netherlands1 aWharton, Robert, A.1 aBertrand-Sarfati, J.1 aMonty, C. uhttps://mcm.lternet.edu/content/stromatolite-mats-antarctic-lakes00593nas a2200133 4500008004100000245014300041210006900184300001200253490000700265100002400272700001800296700002400314856012100338 1993 eng d00aEnvironmental regulators of microbial activity in continental antarctic lakes, in Physical and Biogeochemical Processes in Antarctic Lakes0 aEnvironmental regulators of microbial activity in continental an a165-1950 v591 aSimmons, George, M.1 aVestal, Robie1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/environmental-regulators-microbial-activity-continental-antarctic-lakes-physical-and00582nas a2200133 4500008004100000245012100041210006900162300001200231490000700243100002600250700002100276700003000297856012100327 1993 eng d00aInfluence of high salinity levels on ambient inorganic nitrogen and nitrogen-15 extraction efficiency in Lake Bonney0 aInfluence of high salinity levels on ambient inorganic nitrogen  a245-2460 v281 aBartlett, Richard, D.1 aPriscu, John, C.1 aWoolston, Christopher, D. uhttps://mcm.lternet.edu/content/influence-high-salinity-levels-ambient-inorganic-nitrogen-and-nitrogen-15-extraction00549nas a2200121 4500008004100000245013900041210006900180300001200249490000700261100001900268700002100287856011900308 1993 eng d00aMicrobial communities in the permanent ice cap of Lake Bonney, Antarctica: Relationships among chlorophyll-a , gravel, and nutrients.0 aMicrobial communities in the permanent ice cap of Lake Bonney An a247-2490 v281 aWing, Kate, T.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/microbial-communities-permanent-ice-cap-lake-bonney-antarctica-relationships-among00451nas a2200133 4500008004100000245005600041210005600097300001200153490000700165100001900172700002000191700002100211856008500232 1993 eng d00aNitrifying and denitrifying bacteria in Lake Bonney0 aNitrifying and denitrifying bacteria in Lake Bonney a239-2410 v281 aWard, Bess, B.1 aCockcroft, A.R.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/nitrifying-and-denitrifying-bacteria-lake-bonney00617nas a2200145 4500008004100000245013500041210006900176300001000245490000700255100002400262700002700286700001900313700002300332856011600355 1993 eng d00aPerennial ice covers and their influence on antarctic lake ecosystems, in Physical and Biogeochemical Processes in Antarctic Lakes0 aPerennial ice covers and their influence on antarctic lake ecosy a53-700 v591 aWharton, Robert, A.1 aMcKay, Christopher, P.1 aClow, Gary, D.1 aAndersen, Dale, T. uhttps://mcm.lternet.edu/content/perennial-ice-covers-and-their-influence-antarctic-lake-ecosystems-physical-and00517nas a2200121 4500008004100000245009700041210006900138300001200207490000700219100003000226700002100256856011800277 1993 eng d00aPhytoplankton utilization of ammonium and nitrate in Lake Bonney: A preliminary assessment.0 aPhytoplankton utilization of ammonium and nitrate in Lake Bonney a241-2430 v281 aWoolston, Christopher, D.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/phytoplankton-utilization-ammonium-and-nitrate-lake-bonney-preliminary-assessment00557nas a2200133 4500008004100000245010300041210006900144300001200213490000800225100002400233700001700257700002200274856012700296 1993 eng d00aStable isotopic biogeochemistry of carbon and nitrogen in a perennially ice-covered Antarctic lake0 aStable isotopic biogeochemistry of carbon and nitrogen in a pere a159-1720 v1071 aWharton, Robert, A.1 aLyons, Berry1 aMarais, D.J., Des uhttps://mcm.lternet.edu/content/stable-isotopic-biogeochemistry-carbon-and-nitrogen-perennially-ice-covered-antarctic-lake00549nas a2200157 4500008004100000020001800041245006800059210006800127260001000195300001000205490000700215100002400222700002400246700002400270856009700294 1993 eng d a978087590830400aTerrigenous clastic sedimentation in antarctic dry valley lakes0 aTerrigenous clastic sedimentation in antarctic dry valley lakes bWiley a71-810 v591 aAndersen, David, W.1 aWharton, Robert, A.1 aSquyres, Steven, W. uhttps://mcm.lternet.edu/content/terrigenous-clastic-sedimentation-antarctic-dry-valley-lakes00554nas a2200133 4500008004100000245010200041210006900143300001200212490000700224100002100231700001900252700002400271856012500295 1993 eng d00aWater column transformations of nitrogen in Lake Bonney, a perennially ice-covered antarctic lake0 aWater column transformations of nitrogen in Lake Bonney a perenn a237-2390 v281 aPriscu, John, C.1 aWard, Bess, B.1 aDownes, Malcolm, T. uhttps://mcm.lternet.edu/content/water-column-transformations-nitrogen-lake-bonney-perennially-ice-covered-antarctic-lake00340nas a2200097 4500008004100000245004900041210004800090260001200138100002400150856006800174 1991 eng d00aMcMurdo Dry Valleys: A cold desert ecosystem0 aMcMurdo Dry Valleys A cold desert ecosystem c10/19911 aWharton, Robert, A. uhttps://mcm.lternet.edu/sites/default/files/MCM_1991_Report.pdf