02859nas a2200181 4500008004100000245009200041210006900133260001200202300001400214490000700228520227800235100002002513700002502533700002402558700002102582700002002603856005402623 2024 eng d00aThe application and modification of WRF-Hydro/Glacier to a cold-based Antarctic glacier0 aapplication and modification of WRFHydroGlacier to a coldbased A c02/2024 a459 - 4780 v283 a

The McMurdo Dry Valleys (MDV) are home to a unique microbial ecosystem that is dependent on the availability of freshwater. This is a polar desert and freshwater originates almost entirely from surface and near-surface melt of the cold-based glaciers. Understanding the future evolution of these environments requires the simulation of the full chain of physical processes from net radiative forcing, surface energy balance, melt, runoff and transport of meltwater in stream channels from the glaciers to the terminal lakes where the microbial community resides. To establish a new framework to do this, we present the first application of WRF-Hydro/Glacier in the MDV, which as a fully distributed hydrological model has the capability to resolve the streams from the glaciers to the bare land that surround them. Given that meltwater generation in the MDV is almost entirely dependent on small changes in the energy balance of the glaciers, the aim of this study is to optimize the multi-layer snowpack scheme that is embedded in WRF-Hydro/Glacier to ensure that the feedbacks between albedo, snowfall and melt are fully resolved. To achieve this, WRF-Hydro/Glacier is implemented at a point scale using automatic weather station data on Commonwealth Glacier to physically model the onset, duration and end of melt over a 7-month period (1 August 2021 to 28 February 2022). To resolve the limited energetics controlling melt, it was necessary to (1) limit the percolation of meltwater through the ice layers in the multi-layer snowpack scheme and (2) optimize the parameters controlling the albedo of both snow and ice over the melt season based on observed spectral signatures of albedo. These modifications enabled the variability of broadband albedo over the melt season to be accurately simulated and ensured that modelled surface and near-surface temperatures, surface height change and runoff were fully resolved. By establishing a new framework that couples a detailed snowpack model to a fully distributed hydrological model, this work provides a stepping stone to model the spatial and temporal variability of melt and streamflow in the future, which will enable some of the unknown questions about the hydrological connectivity of the MDV to be answered.

1 aPletzer, Tamara1 aConway, Jonathan, P.1 aCullen, Nicolas, J.1 aEidhammer, Trude1 aKaturji, Marwan uhttps://hess.copernicus.org/articles/28/459/2024/02145nas 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/s40168-023-01719-301497nas a2200169 4500008004100000022001400041245012500055210006900180260001200249300001400261490000700275520092800282100001901210700001601229700002001245856006201265 2023 eng d a1084-545300aBetter together? The values, obstacles, opportunities, and prospects for collaborative research in environmental history0 aBetter together The values obstacles opportunities and prospects c04/2023 a269 - 2990 v283 a

Environmental historians have long argued for the value of collaborative research, many have called for more of it, and some have experimented with new forms of teamwork. Yet data gathered from three prominent journals—Environmental History, Environment and History, and the Journal of Historical Geography—show that, over the fifteen-year period from 2006 through 2020, coauthorship on published research remained remarkably rare, with no discernible trend over time. Why do environmental historians still collaborate so infrequently on published research? What are the causes and consequences of this failure to work together? And how can we help better fulfill long-standing calls in our field for a more collaborative research culture? This essay answers these questions, and it offers practical remedies for fostering a culture of greater collaboration in environmental history.

1 aAlagona, Peter1 aCarey, Mark1 aHowkins, Adrian uhttps://www.journals.uchicago.edu/doi/full/10.1086/72378402499nas 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/2073-4425/14/3/60602814nas 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/10.1029/2022GB00767802348nas a2200253 4500008004100000022001400041245009900055210006900154260001200223300001100235520137700246653002501623653001901648653002401667653003201691653001701723100002601740700002401766700002501790700002501815700003201840700002001872856020201892 2023 eng d a0022-143000aMeteorological drivers of melt at two nearby glaciers in the McMurdo Dry Valleys of Antarctica0 aMeteorological drivers of melt at two nearby glaciers in the McM c12/2023 a1 - 133 a

We study the meteorological drivers of melt at two glaciers in Taylor Valley, Antarctica, using 22 years of weather station observations and surface energy fluxes. The glaciers are located only 30 km apart, but have different local climates; Taylor Glacier is generally drier and windier than Commonwealth Glacier, which receives more snowfall due to its proximity to the coast. Commonwealth Glacier shows more inter-annual melt variability, explained by variable albedo due to summer snowfall events. A significant increase in surface melt at Commonwealth Glacier is associated with a decrease in summer minimum albedo. Inter-annual variability in melt at both glaciers is linked to degree-days above freezing during föhn events, occurring more frequently at Taylor Glacier. At Taylor Glacier melt occurs most often with positive air temperatures, but föhn conditions also favour sublimation, which cools the surface and prevents melt for the majority of the positive air temperatures. At Commonwealth Glacier, most of the melt instead occurs with sub-zero air temperatures, driven by strong solar radiative heating. Future melt at Taylor Glacier will likely be more sensitive to changes in föhn events, while Commonwealth Glacier will be impacted more by changes in near coastal weather, where moisture inputs can drive cloud cover, snowfall and change albedo.

10aAntarctic glaciology10aenergy balance10aglacier meteorology10aice/atmosphere interactions10amelt-surface1 aHofsteenge, Marte, G.1 aCullen, Nicolas, J.1 aConway, Jonathan, P.1 aReijmer, Carleen, H.1 avan den Broeke, Michiel, R.1 aKaturji, Marwan uhttps://www.cambridge.org/core/journals/journal-of-glaciology/article/meteorological-drivers-of-melt-at-two-nearby-glaciers-in-the-mcmurdo-dry-valleys-of-antarctica/2B8ED17DEC26AB5F0905BC4C7ACA02FA02063nas a2200277 4500008004100000245013600041210006900177260001200246300001300258490000600271520117000277100002601447700002601473700002601499700001601525700002101541700002701562700001901589700001901608700002501627700001501652700002101667700002201688700002001710856005501730 2023 eng d00aPostglacial adaptations enabled colonization and quasi-clonal dispersal of ammonia-oxidizing archaea in modern European large lakes0 aPostglacial adaptations enabled colonization and quasiclonal dis c02/2023 aeadc93920 v93 a

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

1 aNgugi, David, Kamanda1 aSalcher, Michaela, M.1 aAndrei, Adrian-Stefan1 aGhai, Rohit1 aKlotz, Franziska1 aChiriac, Maria-Cecilia1 aIonescu, Danny1 aBüsing, Petra1 aGrossart, Hans-Peter1 aXing, Peng1 aPriscu, John, C.1 aAlymkulov, Salmor1 aPester, Michael uhttps://www.science.org/doi/10.1126/sciadv.adc939201137nas a2200193 4500008004100000245005600041210005300097260001200150300001100162490000700173520056500180100002100745700001800766700001400784700002300798700002900821700002600850856006700876 2022 eng d00aAn Antarctic alga that can survive the extreme cold0 aAntarctic alga that can survive the extreme cold c05/2022 a7408380 v103 a

Microscopic algae are tougher than you might think. Some can even survive the extreme cold. In this article, we describe one of the coolest algae of all, the Antarctic green alga called Chlamydomonas sp. UWO241. This one-celled super-organism lives deep in the frigid waters of a remote and permanently ice-covered lake in Antarctica. How does this little alga thrive in such a barren and unwelcoming place? Well, dive into this article to learn how studying the genome of UWO241 is helping scientists better understand this amazingly hardy alga.

1 aSmith, David, R.1 aLeung, Arthur1 aZhang, Xi1 aCvetkovska, Marina1 aMorgan-Kiss, Rachael, M.1 aHüner, Norman, P. A. uhttps://kids.frontiersin.org/articles/10.3389/frym.2022.74083801629nas a2200217 4500008004100000022001400041245007400055210006900129260001200198300001200210490000600222520097000228100002101198700002201219700002401241700001901265700002101284700002101305700001701326856006801343 2022 eng d a2378-224200aBarotropic seiches in a perennially ice-covered lake, East Antarctica0 aBarotropic seiches in a perennially icecovered lake East Antarct c02/2022 a26 - 330 v73 a

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

1 aCastendyk, Devin1 aDugan, Hilary, A.1 aGallagher, Hugh, A.1 aPujara, Nimish1 aDoran, Peter, T.1 aPriscu, John, C.1 aLyons, Berry uhttps://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.1022602219nas a2200349 4500008004100000022001400041245012300055210006900178260001200247520113200259653000901391653001901400653001601419653001201435653000901447653001301456100002001469700002501489700001601514700002501530700002101555700001701576700002501593700002501618700002101643700002501664700002601689700002201715700002301737700001801760856009101778 2022 eng d a0006-356800aCross-site comparisons of dryland ecosystem response to climate change in the US Long-Term Ecological Research Network0 aCrosssite comparisons of dryland ecosystem response to climate c c08/20223 a

Long-term observations and experiments in diverse drylands reveal how ecosystems and services are responding to climate change. To develop generalities about climate change impacts at dryland sites, we compared broadscale patterns in climate and synthesized primary production responses among the eight terrestrial, nonforested sites of the United States Long-Term Ecological Research (US LTER) Network located in temperate (Southwest and Midwest) and polar (Arctic and Antarctic) regions. All sites experienced warming in recent decades, whereas drought varied regionally with multidecadal phases. Multiple years of wet or dry conditions had larger effects than single years on primary production. Droughts, floods, and wildfires altered resource availability and restructured plant communities, with greater impacts on primary production than warming alone. During severe regional droughts, air pollution from wildfire and dust events peaked. Studies at US LTER drylands over more than 40 years demonstrate reciprocal links and feedbacks among dryland ecosystems, climate-driven disturbance events, and climate change.

10aANPP10aclimate change10aDisturbance10adrought10aLTER10awildfire1 aHudson, Amy, R.1 aPeters, Debra, P. C.1 aBlair, J.M.1 aChilders, Daniel, L.1 aDoran, Peter, T.1 aGeil, Kerrie1 aGooseff, Michael, N.1 aGross, Katherine, L.1 aHaddad, Nick, M.1 aPastore, Melissa, A.1 aRudgers, Jennifer, A.1 aSala, Osvaldo, E.1 aSeabloom, Eric, W.1 aShaver, Gaius uhttps://academic.oup.com/bioscience/advance-article/doi/10.1093/biosci/biab134/665484002454nas a2200277 4500008004100000245020000041210006900241260001200310300001400322490000800336520152000344653001501864653001401879653002501893653001801918653001701936653000801953100002401961700001601985700002102001700001902022700001802041700002302059700002902082856006502111 2022 eng d00aCyclic electron flow (CEF) and ascorbate pathway activity provide constitutive photoprotection for the photopsychrophile, Chlamydomonas sp. UWO 241 (renamed Chlamydomonas priscuii)0 aCyclic electron flow CEF and ascorbate pathway activity provide  c03/2022 a235 - 2500 v1513 a

Under environmental stress, plants and algae employ a variety of strategies to protect the photosynthetic apparatus and maintain photostasis. To date, most studies on stress acclimation have focused on model organisms which possess limited to no tolerance to stressful extremes. We studied the ability of the Antarctic alga Chlamydomonas sp. UWO 241 (UWO 241) to acclimate to low temperature, high salinity or high light. UWO 241 maintained robust growth and photosynthetic activity at levels of temperature (2 °C) and salinity (700 mM NaCl) which were nonpermissive for a mesophilic sister species, Chlamydomonas raudensis SAG 49.72 (SAG 49.72). Acclimation in the mesophile involved classic mechanisms, including downregulation of light harvesting and shifts in excitation energy between photosystem I and II. In contrast, UWO 241 exhibited high rates of PSI-driven cyclic electron flow (CEF) and a larger capacity for nonphotochemical quenching (NPQ). Furthermore, UWO 241 exhibited constitutively high activity of two key ascorbate cycle enzymes, ascorbate peroxidase and glutathione reductase and maintained a large ascorbate pool. These results matched the ability of the psychrophile to maintain low ROS under short-term photoinhibition conditions. We conclude that tight control over photostasis and ROS levels are essential for photosynthetic life to flourish in a native habitat of permanent photooxidative stress. We propose to rename this organism Chlamydomonas priscuii.

10aAntarctica10aascorbate10aCyclic electron flow10aPhotosystem I10aPsychrophile10aROS1 aStahl-Rommel, Sarah1 aKalra, Isha1 aD'Silva, Susanna1 aHahn, Mark, M.1 aPopson, Devon1 aCvetkovska, Marina1 aMorgan-Kiss, Rachael, M. uhttps://link.springer.com/article/10.1007/s11120-021-00877-502236nas a2200241 4500008004100000245006500041210006400106260001200170300000900182490000700191520155500198653001501753653002401768653001801792653002601810653001201836653002201848100002501870700001701895700001501912700002101927856004601948 2022 eng d00aGlacial legacies: Microbial communities of Antarctic refugia0 aGlacial legacies Microbial communities of Antarctic refugia c10/2022 a14400 v113 a

In the cold deserts of the McMurdo Dry Valleys (MDV) the suitability of soil for microbial life is determined by both contemporary processes and legacy effects. Climatic changes and accompanying glacial activity have caused local extinctions and lasting geochemical changes to parts of these soil ecosystems over several million years, while areas of refugia may have escaped these disturbances and existed under relatively stable conditions. This study describes the impact of historical glacial and lacustrine disturbance events on microbial communities across the MDV to investigate how this divergent disturbance history influenced the structuring of microbial communities across this otherwise very stable ecosystem. Soil bacterial communities from 17 sites representing either putative refugia or sites disturbed during the Last Glacial Maximum (LGM) (22–17 kya) were characterized using 16 S metabarcoding. Regardless of geographic distance, several putative refugia sites at elevations above 600 m displayed highly similar microbial communities. At a regional scale, community composition was found to be influenced by elevation and geographic proximity more so than soil geochemical properties. These results suggest that despite the extreme conditions, diverse microbial communities exist in these putative refugia that have presumably remained undisturbed at least through the LGM. We suggest that similarities in microbial communities can be interpreted as evidence for historical climate legacies on an ecosystem-wide scale.

10aAntarctica10aMcMurdo Dry Valleys10ametabarcoding10amicrobial communities10arefugia10asoil biodiversity1 aJackson, Abigail, C.1 aJorna, Jesse1 aChaston, J1 aAdams, Byron, J. uhttps://www.mdpi.com/2079-7737/11/10/144002435nas a2200277 4500008004100000245011000041210006900151260001200220300000700232490000700239520155100246653001501797653002601812653002401838653001301862653003001875100001901905700002401924700002101948700002401969700002101993700002302014700002202037700003302059856006502092 2022 eng d00aLimits to the three domains of life: Lessons from community assembly along an Antarctic salinity gradient0 aLimits to the three domains of life Lessons from community assem c04/2022 a150 v263 a

Extremophiles exist among all three domains of life; however, physiological mechanisms for surviving harsh environmental conditions differ among Bacteria, Archaea and Eukarya. Consequently, we expect that domain-specific variation of diversity and community assembly patterns exist along environmental gradients in extreme environments. We investigated inter-domain community compositional differences along a high-elevation salinity gradient in the McMurdo Dry Valleys, Antarctica. Conductivity for 24 soil samples collected along the gradient ranged widely from 50 to 8355 µS cm-1. Taxonomic richness varied among domains, with a total of 359 bacterial, 2 archaeal, 56 fungal, and 69 non-fungal eukaryotic operational taxonomic units (OTUs). Richness for bacteria, archaea, fungi, and non-fungal eukaryotes declined with increasing conductivity (all P < 0.05). Principal coordinate ordination analysis (PCoA) revealed significant (ANOSIM R = 0.97) groupings of low/high salinity bacterial OTUs, while OTUs from other domains were not significantly clustered. Bacterial beta diversity was unimodally distributed along the gradient and had a nested structure driven by species losses, whereas in fungi and non-fungal eukaryotes beta diversity declined monotonically without strong evidence of nestedness. Thus, while increased salinity acts as a stressor in all domains, the mechanisms driving community assembly along the gradient differ substantially between the domains.

10aAntarctica10ainter-domain response10aMcMurdo Dry Valleys10asalinity10aspecies richness patterns1 aJiang, Xiaoben1 aVan Horn, David, J.1 aOkie, Jordan, G.1 aBuelow, Heather, N.1 aSchwartz, Egbert1 aColman, Daniel, R.1 aFeeser, Kelli, L.1 aTakacs-Vesbach, Cristina, D. uhttps://link.springer.com/article/10.1007/s00792-022-01262-302675nas a2200241 4500008004100000245018700041210006900228260001200297300000900309490000700318520179100325653003202116653002602148653002302174653003502197653001902232653002802251100002602279700002002305700002002325700002402345856006402369 2022 eng d00aPatterns of interdisciplinary collaboration resemble biogeochemical relationships in the McMurdo Dry Valleys, Antarctica: A historical social network analysis of science, 1907–20160 aPatterns of interdisciplinary collaboration resemble biogeochemi c04/2022 a80370 v413 a

Co-authorship networks can provide key insights into the production of scientific knowledge. This is particularly interesting in Antarctica, where most human activity relates to scientific research. Bibliometric studies of Antarctic science have provided a useful understanding of international and interdisciplinary collaboration, yet most research has focused on broad-scale analyses over recent time periods. Here, we take advantage of a ‘Goldilocks’ opportunity in the McMurdo Dry Valleys, an internationally important region of Antarctica and the largest ice-free region on the continent. The McMurdo Dry Valleys have attracted continuous and diverse scientific activity since 1958. It is a geographically confined region with limited access, making it possible to evaluate the influence of specific events and individuals. We trace the history of environmental science in this region using bibliometrics and social network analysis. Our results show a marked shift in focus from the geosciences to the biosciences, which mirrors wider trends in the history of science. Collaboration among individuals and academic disciplines increased through time, and the most productive scientists in the network are also the most interdisciplinary. Patterns of collaboration among disciplines resemble the biogeochemical relationships among respective landscape features, raising interesting questions about the role of the material environment in the development of scientific networks in the region, and the dynamic interaction with socio-cultural and political factors. Our focused, historical approach adds nuance to broad-scale bibliometric studies and could be applied to understanding the dynamics of scientific research in other regions of Antarctica and elsewhere.

10acritical physical geography10aenvironmental history10ahistory of science10ascience and technology studies10ascientometrics10avisual network analysis1 aChignell, Stephen, M.1 aHowkins, Adrian1 aGullett, Poppie1 aFountain, Andrew, G uhttps://polarresearch.net/index.php/polar/article/view/803703572nas a2200301 4500008004100000245010000041210006900141260001200210300001100222490000800233520264300241653002302884653001002907653002002917653002202937653002602959653001902985653001603004100002603020700002103046700002303067700001403090700002603104700002303130700001603153700002903169856007203198 2022 eng d00aPhotosynthetic adaptation to polar life: Energy balance, photoprotection and genetic redundancy0 aPhotosynthetic adaptation to polar life Energy balance photoprot c01/2022 a1535570 v2683 a

The persistent low temperature that characterize polar habitats combined with the requirement for light for all photoautotrophs creates a conundrum. The absorption of too much light at low temperature can cause an energy imbalance that decreases photosynthetic performance that has a negative impact on growth and can affect long-term survival. The goal of this review is to survey the mechanism(s) by which polar photoautotrophs maintain cellular energy balance, that is, photostasis to overcome the potential for cellular energy imbalance in their low temperature environments. Photopsychrophiles are photosynthetic organisms that are obligately adapted to low temperature (0-15 °C) but usually die at higher temperatures (≥20 °C). In contrast, photopsychrotolerant species can usually tolerate and survive a broad range of temperatures (5-40 °C). First, we summarize the basic concepts of excess excitation energy, energy balance, photoprotection and photostasis and their importance to survival in polar habitats. Second, we compare the photoprotective mechanisms that underlie photostasis and survival in aquatic cyanobacteria and green algae as well as terrestrial Antarctic and Arctic plants. We show that polar photopsychrophilic and photopsychrotolerant organisms attain energy balance at low temperature either through a regulated reduction in the efficiency of light absorption or through enhanced capacity to consume photosynthetic electrons by the induction of O2 as an alternative electron acceptor. Finally, we compare the published genomes of three photopsychrophilic and one photopsychrotolerant alga with five mesophilic green algae including the model green alga, Chlamydomonas reinhardtii. We relate our genomic analyses to photoprotective mechanisms that contribute to the potential attainment of photostasis. Finally, we discuss how the observed genomic redundancy in photopsychrophilic genomes may confer energy balance, photoprotection and resilience to their harsh polar environment. Primary production in aquatic, Antarctic and Arctic environments is dependent on diverse algal and cyanobacterial communities. Although mosses and lichens dominate the Antarctic terrestrial landscape, only two extant angiosperms exist in the Antarctic. The identification of a single ‘molecular key’ to unravel adaptation of photopsychrophily and photopsychrotolerance remains elusive. Since these photoautotrophs represent excellent biomarkers to assess the impact of global warming on polar ecosystems, increased study of these polar photoautotrophs remains essential.

10agenomic redundancy10alight10aphotoprotection10aphotopsychrophily10aphotopsychrotolerance10aPhotosynthesis10atemperature1 aHüner, Norman, P. A.1 aSmith, David, R.1 aCvetkovska, Marina1 aZhang, Xi1 aIvanov, Alexander, G.1 aSzyszka-Mroz, Beth1 aKalra, Isha1 aMorgan-Kiss, Rachael, M. uhttps://www.sciencedirect.com/science/article/pii/S017616172100196602569nas 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.221280011902273nas a2200205 4500008004100000022001400041245012200055210006900177260001200246490000800258520159800266653001401864653001901878653002201897653001901919100002001938700002701958700002101985856006102006 2022 eng d a2169-900300aWintertime brine discharge at the surface of a cold polar glacier and the unexpected absence of associated seismicity0 aWintertime brine discharge at the surface of a cold polar glacie c03/20220 v1273 a

A subglacial groundwater system beneath Taylor Glacier, Antarctica, discharges hypersaline, iron-rich brine episodically at the glacier surface to create Blood Falls. However, the triggering mechanism for these brine release events is not yet understood. Identifying which fracture processes are observed seismically can help us better characterize the hydrological system at Taylor Glacier, and more generally, provide us with a broader understanding of englacial hydrologic activity in cold glaciers. We document wintertime brine discharge using time-lapse photography. Subfreezing air temperatures during the brine discharge indicate that surface melt-induced hydrofracture is an unlikely trigger for brine release. Further, we analyze local seismic data to test a hypothesis that fracturing generates elevated surface wave energy preceding and/or coinciding with brine release events. Our results show no discernible elevated Rayleigh wave activity prior to or during Blood Falls brine release. Instead, we find a pattern of seismic events dominated by a seasonal signal, with more Rayleigh events occurring in the summer than the winter from the Blood Falls source area. We calculate that the volumetric opening of cracks that would generate Rayleigh waves at our detection limits are of similar size to myriad cracks in glacier ice, lake ice, and frozen sediment in the terminus area. We therefore propose that any fracturing coincident with brine release activity likely consists of a series of smaller opening events that are masked by other seismicity in the local environment.

10acrevasses10acryoseismology10aglacier hydrology10aRayleigh waves1 aCarr, Chris, G.1 aCarmichael, Joshua, D.1 aPettit, Erin, C. uhttps://onlinelibrary.wiley.com/doi/10.1029/2021JF00632503115nas 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.1267904166nas a2200565 4500008004100000022001400041245007900055210006900134260001200203300001100215490000700226520245300233653001802686653002702704653001902731653001902750653001202769653001202781653001502793653008902808653002002897100002302917700002502940700002602965700002702991700002103018700002503039700001703064700002203081700002903103700002603132700002403158700002603182700002403208700002103232700001603253700002703269700002403296700002303320700002203343700002403365700002303389700001503412700002203427700002103449700002203470700002603492700002403518856005803542 2021 eng d a2150-892500aConnectivity: Insights from the U.S. Long Term Ecological Research Network0 aConnectivity Insights from the US Long Term Ecological Research  c05/2021 ae034320 v123 a

Ecosystems across the United States are changing in complex and surprising ways. Ongoing demand for critical ecosystem services requires an understanding of the populations and communities in these ecosystems in the future. This paper represents a synthesis effort of the U.S. National Science Foundation-funded Long-Term Ecological Research (LTER) network addressing the core research area of “populations and communities.” The objective of this effort was to show the importance of long-term data collection and experiments for addressing the hardest questions in scientific ecology that have significant implications for environmental policy and management. Each LTER site developed at least one compelling case study about what their site could look like in 50–100 yr as human and environmental drivers influencing specific ecosystems change. As the case studies were prepared, five themes emerged, and the studies were grouped into papers in this LTER Futures Special Feature addressing state change, connectivity, resilience, time lags, and cascading effects. This paper addresses the “connectivity” theme and has examples from the Phoenix (urban), Niwot Ridge (alpine tundra), McMurdo Dry Valleys (polar desert), Plum Island (coastal), Santa Barbara Coastal (coastal), and Jornada (arid grassland and shrubland) sites. Connectivity has multiple dimensions, ranging from multi-scalar interactions in space to complex interactions over time that govern the transport of materials and the distribution and movement of organisms. The case studies presented here range widely, showing how land-use legacies interact with climate to alter the structure and function of arid ecosystems and flows of resources and organisms in Antarctic polar desert, alpine, urban, and coastal marine ecosystems. Long-term ecological research demonstrates that connectivity can, in some circumstances, sustain valuable ecosystem functions, such as the persistence of foundation species and their associated biodiversity or, it can be an agent of state change, as when it increases wind and water erosion. Increased connectivity due to warming can also lead to species range expansions or contractions and the introduction of undesirable species. Continued long-term studies are essential for addressing the complexities of connectivity. The diversity of ecosystems within the LTER network is a strong platform for these studies.

10aalpine tundra10aAntarctic polar desert10aarid grassland10aarid shrubland10acoastal10aestuary10asalt marsh10aSpecial Feature: Forecasting Earth’s Ecosystems with Long-Term Ecological Research10aurban ecosystem1 aIwaniec, David, M.1 aGooseff, Michael, N.1 aSuding, Katharine, N.1 aJohnson, David, Samuel1 aReed, Daniel, C.1 aPeters, Debra, P. C.1 aAdams, Byron1 aBarrett, John, E.1 aBestelmeyer, Brandon, T.1 aCastorani, Max, C. N.1 aCook, Elizabeth, M.1 aDavidson, Melissa, J.1 aGroffman, Peter, M.1 aHanan, Niall, P.1 aHuenneke, L1 aJohnson, Pieter, T. J.1 aMcKnight, Diane, M.1 aMiller, Robert, J.1 aOkin, Gregory, S.1 aPreston, Daniel, L.1 aRassweiler, Andrew1 aRay, Chris1 aSala, Osvaldo, E.1 aSchooley, Robert1 aSeastedt, Timothy1 aSpasojevic, Marko, J.1 aVivoni, Enrique, R. uhttps://onlinelibrary.wiley.com/doi/10.1002/ecs2.343202080nas a2200361 4500008004100000245006800041210006800109260001200177300000900189490000700198520108000205653001501285653001701300653001201317653001301329653001501342653000901357100001901366700002401385700001801409700002101427700002501448700002501473700002201498700002001520700001901540700001701559700002601576700001601602700001801618710002301636856005901659 2021 eng d00aDiatoms define a novel freshwater biogeography of the Antarctic0 aDiatoms define a novel freshwater biogeography of the Antarctic c01/2021 a1-130 v443 a

Terrestrial biota in the Antarctic are more globally distinct and highly structured biogeographically than previously believed, but information on biogeographic patterns and endemism in freshwater communities is largely lacking. We studied biogeographic patterns of Antarctic freshwater diatoms based on the analysis of species occurrences in a dataset of 439 lakes spread across the Antarctic realm. Highly distinct diatom floras, both in terms of composition and richness, characterize Continental Antarctica, Maritime Antarctica and the sub-Antarctic islands, with marked biogeographic provincialism in each region. A total of 44% of all species is estimated to be endemic to the Antarctic, and most of them are confined to a single biogeographic region. The level of endemism significantly increases with increasing latitude and geographic isolation. Our results have implications for conservation planning, and suggest that successful dispersal of freshwater diatoms to and within the Antarctic is limited, fostering the evolution of highly endemic diatom floras.

10aAntarctica10abiogeography10adiatoms10aendemism10afreshwater10alake1 aVerleyen, Elie1 aVan de Vijver, Bart1 aTytgat, Bjorn1 aPinseel, Eveline1 aHodgson, Dominic, A.1 aKopalová, Kateřina1 aChown, Steven, L.1 aVan Ranst, Eric1 aImura, Satoshi1 aKudoh, Sakae1 aVan Nieuwenhuyze, Wim1 aSabbe, Koen1 aVyverman, Wim1 aANTDIAT consortium uhttps://onlinelibrary.wiley.com/doi/10.1111/ecog.0537401659nas a2200193 4500008004100000022001300041245008600054210006900140260001200209300001100221490000700232520104000239100001401279700002301293700002901316700002601345700002201371856007201393 2021 eng d a2589004200aDraft genome sequence of the Antarctic green alga Chlamydomonas sp. UWO2410 aDraft genome sequence of the Antarctic green alga IChlamydomonas c2021-02 a1020840 v243 a

Antarctica is home to an assortment of psychrophilic algae, which have evolved various survival strategies for coping with their frigid environments. Here, we explore Antarctic psychrophily by examining the ∼212 Mb draft nuclear genome of the green alga Chlamydomonas sp. UWO241, which resides within the water column of a perennially ice-covered, hypersaline lake. Like certain other Antarctic algae, UWO241 encodes a large number (≥37) of ice-binding proteins, putatively originating from horizontal gene transfer. Even more striking, UWO241 harbors hundreds of highly similar duplicated genes involved in diverse cellular processes, some of which we argue are aiding its survival in the Antarctic via gene dosage. Gene and partial gene duplication appear to be an ongoing phenomenon within UWO241, one which might be mediated by retrotransposons. Ultimately, we consider how such a process could be associated with adaptation to extreme environments but explore potential non-adaptive hypotheses as well.

1 aZhang, Xi1 aCvetkovska, Marina1 aMorgan-Kiss, Rachael, M.1 aHüner, Norman, P. A.1 aSmith, David, Roy uhttps://www.sciencedirect.com/science/article/pii/S258900422100052301860nas a2200205 4500008004100000022001400041245015300055210006900208260001200277520112000289100002201409700002001431700002001451700002501471700001701496700002401513700002501537700002401562856006801586 2021 eng d a2378-224200aFrom the Heroic Age to today: What diatoms from Shackleton's Nimrod expedition can tell us about the ecological trajectory of Antarctic ponds0 aFrom the Heroic Age to today What diatoms from Shackletons iNimr c07/20213 a

Biological invasion and environmental change pose major threats to ecosystems. While long-term ecological change is commonly evaluated through sediment cores in lakes, it is generally not feasible for smaller ponds, and spatial resolution is limited. Here, we analyze pond diatom communities collected during Shackleton's Nimrod expedition at Cape Royds, Antarctica, to compare with the same waterbodies a century later. We find historical samples to be almost identical to modern counterparts, and provide no evidence of exotic introductions despite increasing human activity. However, a shift occurred in the pond nearest Shackleton's hut, Pony Lake, which was dominated by Luticola muticopsis a century ago, and was replaced by Craspedostauros laevissimus. Both are endemic species previously and currently present at Cape Royds, and we hypothesize that a shift in conductivity accompanying changing precipitation patterns may be responsible. Collectively, these results provide important data for assessing human and climate impacts among Antarctic lacustrine habitats.

1 aKohler, Tyler, J.1 aHowkins, Adrian1 aSokol, Eric, R.1 aKopalová, Kateřina1 aCox, Aneliya1 aDarling, Joshua, P.1 aGooseff, Michael, N.1 aMcKnight, Diane, M. uhttps://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.1020001774nas a2200229 4500008004100000245011600041210006900157260001200226520104400238653001601282653001801298653001401316653001801330653002401348653001601372653001501388100001801403700001901421700002501440700002101465856005801486 2021 eng d00aHow long do population level field experiments need to be? Utilising data from the 40‐year‐old LTER network0 aHow long do population level field experiments need to be Utilis c02/20213 a

We utilise the wealth of data accessible through the 40‐year‐old Long‐Term Ecological Research (LTER) network to ask if aspects of the study environment or taxa alter the duration of research necessary to detect consistent results. To do this, we use a moving‐window algorithm. We limit our analysis to long‐term (> 10 year) press experiments recording organismal abundance. We find that studies conducted in dynamic abiotic environments need longer periods of study to reach consistent results, as compared to those conducted in more moderated environments. Studies of plants were more often characterised by spurious results than those on animals. Nearly half of the studies we investigated required 10 years or longer to become consistent, where all significant trends agreed in direction, and four studies (of 100) required longer than 20 years. Here, we champion the importance of long‐term data and bolster the value of multi‐decadal experiments in understanding, explaining and predicting long‐term trends.

10adata mining10aisothermality10along-term10amoving window10apopulation dynamics10atime series10atrajectory1 aCusser, Sarah1 aHelms, Jackson1 aBahlai, Christie, A.1 aHaddad, Nick, M. uhttps://onlinelibrary.wiley.com/doi/10.1111/ele.1371002329nas 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/S266690052100025301817nas a2200169 4500008004100000245017100041210006900212260001200281300001300293490000700306520116600313100002601479700002001505700002001525700002401545856007801569 2021 eng d00aResearch sites get closer to field camps over time: Informing environmental management through a geospatial analysis of science in the McMurdo Dry Valleys, Antarctica0 aResearch sites get closer to field camps over time Informing env c11/2021 ae02579500 v163 a

As in many parts of the world, the management of environmental science research in Antarctica relies on cost-benefit analysis of negative environmental impact versus positive scientific gain. Several studies have examined the environmental impact of Antarctic field camps, but very little work looks at how the placement of these camps influences scientific research. In this study, we integrate bibliometrics, geospatial analysis, and historical research to understand the relationship between field camp placement and scientific production in the McMurdo Dry Valleys of East Antarctica. Our analysis of the scientific corpus from 1907–2016 shows that, on average, research sites have become less dispersed and closer to field camps over time. Scientific output does not necessarily correspond to the number of field camps, and constructing a field camp does not always lead to a subsequent increase in research in the local area. Our results underscore the need to consider the complex historical and spatial relationships between field camps and research sites in environmental management decision-making in Antarctica and other protected areas.

1 aChignell, Stephen, M.1 aMyers, Madeline1 aHowkins, Adrian1 aFountain, Andrew, G uhttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.025795002207nas 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.19.0128002447nas a2200181 4500008004100000245007900041210006900120260001200189490000700201520187300208100002002081700002602101700002002127700002402147700001902171700002102190856005402211 2020 eng d00aA digital archive of human activity in the McMurdo Dry Valleys, Antarctica0 adigital archive of human activity in the McMurdo Dry Valleys Ant c05/20200 v123 a

Over the last half century, the McMurdo Dry Valleys (MDV) of East Antarctica have become a globally important site for scientific research and environmental monitoring. Historical data can make important contributions to current research activities and environmental management in Antarctica but tend to be widely scattered and difficult to access. We address this need in the MDV by compiling over 5000 historical photographs, sketches, maps, oral interviews, publications, and other archival resources into an online digital archive. The data have been digitized and georeferenced using a standardized metadata structure, which enables intuitive searches and data discovery via an online interface. The ultimate aim of the archive is to create as comprehensive as possible a record of human activity in the MDV to support ongoing research, management, and conservation efforts. This is a valuable tool for scientists seeking to understand the dynamics of change in lakes, glaciers, and other physical systems, as well as humanistic inquiry into the history of the Southern Continent. In addition to providing benchmarks for understanding change over time, the data can help target field sampling for studies working under the assumption of a pristine landscape by enabling researchers to identify the date and extent of past human activities. The full database is accessible via a web browser-based interface hosted by the McMurdo Long Term Ecological Research site: http://mcmurdohistory.lternet.edu/ (last access: 5 May 2020). The complete metadata data for all resources in the database are also available at the Environmental Data Initiative: https://doi.org/10.6073/pasta/6744cb28a544fda827805db123d36557 (Howkins et al., 2019).

1 aHowkins, Adrian1 aChignell, Stephen, M.1 aGullett, Poppie1 aFountain, Andrew, G1 aBrett, Melissa1 aPreciado, Evelin uhttps://www.earth-syst-sci-data.net/12/1117/2020/02303nas 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/S0012821X2030404001957nas a2200133 4500008004100000245010200041210006900143260005300212490000900265520146100274100002201735700002401757856004201781 2020 eng d00aGlacial meltwater modeling to simulate lake water budget (1996-2013) in Taylor Valley, Antarctica0 aGlacial meltwater modeling to simulate lake water budget 1996201 aPortland, ORbPortland State Universityc01/20200 vM.S.3 a

The McMurdo Dry Valleys (MDV), the largest ice-free region (4,500 km2) in Antarctica, are a polar desert with an average annual temperature of -18 ̊C. In Taylor Valley, one of the MDV, closed-basin, perennially ice-covered lakes occupy the valley floor. Their water balance is controlled by inflow from glacial meltwater runoff and loss due to sublimation, making them sensitive indicators of climate. In this study, a physically-based model of glacier meltwater and lake ice sublimation is adapted to explain modern (1996 to 2013) lake-level variations. Meltwater model results were improved by the inclusion of MODIS remotely-sensed albedo measurements (E = 0.47; nRMSE = 0.73). After 2008 the meltwater model significantly under-predicted streamflow and only through decreasing albedo by -30% (equivalent to a decrease of -0.18 on average) did the results match observations (E = 0.79; nRMSE = 0.45). This study provides the first estimate of direct (unmeasured) glacier inflow to the lakes, 69%, 73% and 28%, and sublimation loss rates, 0.37 m yr-1, 0.24 m yr-1 and 0.16 m yr-1, for Lakes Bonney, Hoare and Fryxell, respectively. Despite similar meltwater volumes entering Lakes Bonney and Fryxell, the difference in basin hypsometry results in a much faster lake rise at Bonney from 2002-13. If future climate conditions match current (1996-2013) conditions, all lakes will rise through the end of the century.

1 aCross, Julian, M.1 aFountain, Andrew, G uhttps://archives.pdx.edu/ds/psu/3080603683nas 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/s41597-020-0437-302262nas a2200145 4500008004100000245013600041210006900177260001200246520154000258100002001798700002301818700002101841700002001862856023401882 2020 eng d00aThe influence of environmental microseismicity on detection and interpretation of small-magnitude events in a polar glacier setting0 ainfluence of environmental microseismicity on detection and inte c07/20203 a

Glacial environments exhibit temporally variable microseismicity. To investigate how microseismicity influences event detection, we implement two noise-adaptive digital power detectors to process seismic data from Taylor Glacier, Antarctica. We add scaled icequake waveforms to the original data stream, run detectors on the hybrid data stream to estimate reliable detection magnitudes and compare analytical magnitudes predicted from an ice crack source model. We find that detection capability is influenced by environmental microseismicity for seismic events with source size comparable to thermal penetration depths. When event counts and minimum detectable event sizes change in the same direction (i.e. increase in event counts and minimum detectable event size), we interpret measured seismicity changes as ‘true’ seismicity changes rather than as changes in detection. Generally, one detector (two degree of freedom (2dof)) outperforms the other: it identifies more events, a more prominent summertime diurnal signal and maintains a higher detection capability. We conclude that real physical processes are responsible for the summertime diurnal inter-detector difference. One detector (3dof) identifies this process as environmental microseismicity; the other detector (2dof) identifies it as elevated waveform activity. Our analysis provides an example for minimizing detection biases and estimating source sizes when interpreting temporal seismicity patterns to better infer glacial seismogenic processes.

1 aCarr, Chris, G.1 aCarmichael, J., D.1 aPettit, Erin, C.1 aTruffer, Martin uhttps://www.cambridge.org/core/journals/journal-of-glaciology/article/influence-of-environmental-microseismicity-on-detection-and-interpretation-of-smallmagnitude-events-in-a-polar-glacier-setting/E1A441425341F677117509351F3C676302448nas a2200217 4500008004100000245010000041210006900141260001200210490000700222520174400229100001201973700001901985700002702004700002102031700001602052700001702068700002902085700002302114700002102137856007202158 2020 eng d00aMethane production in the oxygenated water column of a perennially ice‐covered Antarctic lake0 aMethane production in the oxygenated water column of a perennial c01/20200 v653 a

Aerobic methane production in aquatic ecosystems impacts the global atmospheric budget of methane, but the extent, mechanism, and taxa responsible for producing this greenhouse gas are not fully understood. Lake Bonney (LB), a perennially ice‐covered Antarctic lake, has cold hypersaline waters underlying an oxygenated freshwater layer. We present temporal methane concentration profiles in LB indicating methane production in the oxygenated (> 200% air saturation) water. Experiments amended with methylphosphonate (MPn) yielded methane generation, suggesting in situ methanogenesis via the carbon‐phosphorus (C‐P) lyase pathway. Enrichment cultures from the lake were used to isolate five bacterial strains capable of generating methane when supplied with MPn as the sole P source. Based on 16S rRNA gene sequencing, the isolates belong to the Proteobacteria (closely related to Marinomonas, Hoeflea, and Marinobacter genera) and Bacteroidetes (Algoriphagus genus). 16S rRNA metagenomic sequencing confirms the presence of these taxa in LB. None of the isolated species were reported to be capable to produce methane. In addition, orthologs of the phosphoenolpyruvate mutase gene (PepM) and methylphosphonate synthase (MPnS), enzymes involved in phosphonate and MPn biosynthesis, were widely spread in the LB shotgun metagenomic libraries; genes related to C‐P lyase pathways (phn gene clusters) were also abundant. 16S rRNA and mcrA genes of anaerobic methanogens were absent in both 16S rRNA and metagenomics libraries. These data reveal that in situ aerobic biological methane production is likely a significant source of methane in LB.

1 aLi, Wei1 aDore, John, E.1 aSteigmeyer, August, J.1 aCho, Yong‐Joon1 aKim, Ok-Sun1 aLiu, Yongqin1 aMorgan-Kiss, Rachael, M.1 aSkidmore, Mark, L.1 aPriscu, John, C. uhttps://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.1125702368nas 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/10.1029/2020JG00567903158nas a2200181 4500008004100000245011200041210006900153260001200222300001200234490000700246520256300253100002402816700002502840700002002865700002102885700002202906856004802928 2020 eng d00aThe seasonal evolution of albedo across glaciers and the surrounding landscape of Taylor Valley, Antarctica0 aseasonal evolution of albedo across glaciers and the surrounding c03/2020 a769-7880 v143 a

The McMurdo Dry Valleys (MDVs) of Antarctica are a polar desert ecosystem consisting of alpine glaciers, ice-covered lakes, streams, and expanses of vegetation-free rocky soil. Because average summer temperatures are close to 0 ∘C, the MDV ecosystem in general, and glacier melt dynamics in particular, are both closely linked to the energy balance. A slight increase in incoming radiation or change in albedo can have large effects on the timing and volume of meltwater. However, the seasonal evolution or spatial variability of albedo in the valleys has yet to fully characterized. In this study, we aim to understand the drivers of landscape albedo change within and across seasons. To do so, a box with a camera, GPS, and shortwave radiometer was hung from a helicopter that flew transects four to five times a season along Taylor Valley. Measurements were repeated over three seasons. These data were coupled with incoming radiation measured at six meteorological stations distributed along the valley to calculate the distribution of albedo across individual glaciers, lakes, and soil surfaces. We hypothesized that albedo would decrease throughout the austral summer with ablation of snow patches and increasing sediment exposure on the glacier and lake surfaces. However, small snow events (<6 mm water equivalent) coupled with ice whitening caused spatial and temporal variability of albedo across the entire landscape. Glaciers frequently followed a pattern of increasing albedo with increasing elevation, as well as increasing albedo moving from east to west laterally across the ablation zone. We suggest that spatial patterns of albedo are a function of landscape morphology trapping snow and sediment, longitudinal gradients in snowfall magnitude, and wind-driven snow redistribution from east to west along the valley. We also compare our albedo measurements to the MODIS albedo product and found that overall the data have reasonable agreement. The mismatch in spatial scale between these two datasets results in variability, which is reduced after a snow event due to albedo following valley-scale gradients of snowfall magnitude. These findings highlight the importance of understanding the spatial and temporal variability in albedo and the close coupling of climate and landscape response. This new understanding of landscape albedo can constrain landscape energy budgets, better predict meltwater generation on from MDV glaciers, and how these ecosystems will respond to changing climate at the landscape scale.

1 aBergstrom, Anna, J.1 aGooseff, Michael, N.1 aMyers, Madeline1 aDoran, Peter, T.1 aCross, Julian, M. uhttps://www.the-cryosphere.net/14/769/2020/02357nas a2200205 4500008004100000245012200041210006900163260001200232490000700244520163100251100002501882700002701907700001801934700002501952700002501977700002902002700002502031700002302056856007202079 2020 eng d00aVertical stratification and stability of biogeochemical processes in the deep saline waters of Lake Vanda, Antarctica0 aVertical stratification and stability of biogeochemical processe c03/20200 v653 a

Lake Vanda is a permanently ice-covered lake in the McMurdo Dry Valleys of Antarctica. Its bottom waters remain stratified year-round because of a strong salinity-driven density gradient. We have assessed spatial patterns in and relationships between major biogeochemical processes in the water column of Lake Vanda. Samples were collected in the austral summers of 2008 and 2011 to measure concentrations of metabolites associated with a suite of biogeochemical processes across the deep salinity gradient. The shapes of the resulting geochemical profiles were consistent between 2008 and 2011. Metabolite production and consumption rates were estimated using a reactive transport model based on the assumption that vertical diffusion was the only activephysical transport process. We validated this model for nitrification by using stable isotope incubations to show that this process was only active at depths predicted by the model. No nitrification activity was observed at 68 m depth in spite of overlapping oxygen and ammonium gradients. We attribute this lack of activity to the competitive inhibition of ammonia monooxygenase by methane. Net nitrous oxide and nitrate consumption were observed in the oxic water column, providing evidence of aerobic denitrification. The depth of maximum net oxygen production did not coincide with the deep chlorophyll maxima (at 59.3, 63, and 68.2 m) measured in the same profile. Finally, the integrated sulfide oxidation rate was high compared with other oxidation processes, indicating that sulfide was an important electron donor for the water column microbial community.

1 aSchutte, Charles, A.1 aSamarkin, Vladimir, A.1 aPeters, Brian1 aMadigan, Michael, T.1 aBowles, Marshall, W.1 aMorgan-Kiss, Rachael, M.1 aCasciotti, Karen, L.1 aJoye, Samantha, B. uhttps://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.1132702684nas 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/s42003-018-0274-502367nas a2200205 4500008004100000245011400041210006900155260001200224300001400236490000800250520166200258100002501920700002701945700002801972700002602000700002002026700002002046700002102066856007402087 2019 eng d00aDifferential incorporation of bacteria, organic matter, and inorganic ions into lake ice during ice formation0 aDifferential incorporation of bacteria organic matter and inorga c02/2019 a585 - 6000 v1243 a

The segregation of bacteria, inorganic solutes, and total organic carbon between liquid water and ice during winter ice formation on lakes can significantly influence the concentration and survival of microorganisms in icy systems, and their roles in biogeochemical processes. Our study quantifies the distributions of bacteria and solutes between liquid and solid water phases during progressive freezing. We simulated lake ice formation in mesocosm experiments using water from perennially (Antarctica) and seasonally (Alaska and Montana, USA) ice covered lakes. We then computed concentration factors and effective segregation coefficients, which are parameters describing the incorporation of bacteria and solutes into ice. Experimental results revealed that, contrary to major ions, bacteria were readily incorporated into ice and did not concentrate in the liquid phase. The organic matter incorporated into the ice was labile, amino acid-like material, differing from the humic-like compounds that remained in the liquid phase. Results from a control mesocosm experiment (dead bacterial cells) indicated that viability of bacterial cells did not influence the incorporation of free bacterial cells into ice, but did have a role in the formation and incorporation of bacterial aggregates. Together, these findings demonstrate that bacteria, unlike other solutes, were preferentially incorporated into lake-ice during our freezing experiments, a process controlled mainly by the initial solute concentration of the liquid water source, regardless of cell viability.

1 aSantibáñez, Pamela1 aMichaud, Alexander, B.1 aVick-Majors, Trista, J.1 aD’Andrilli, Juliana1 aChiuchiolo, Amy1 aHand, Kevin, P.1 aPriscu, John, C. uhttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JG00482501931nas 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.html02573nas a2200265 4500008004100000022001400041245010400055210006900159260001200228300001400240490000700254520177600261653002002037653002102057653001502078653001702093653002402110653001202134653002502146100001202171700002002183700001602203700002902219856005902248 2019 eng d a0948-305500aDrivers of protistan community autotrophy and heterotrophy in chemically stratified Antarctic lakes0 aDrivers of protistan community autotrophy and heterotrophy in ch c01/2019 a225 - 2390 v823 a

Single-celled, eukaryotic microorganisms, known as protists, are responsible for 2 important, yet opposing, metabolic activities within aquatic food webs. They are major primary producers and highly active predators in marine and fresh water systems. While genomics has accelerated in recent years for this taxonomically diverse group, our understanding of the metabolic capabilities of most protists remains limited. It is also poorly understood how protist trophic mode is affected by biotic and abiotic factors, and therefore it is difficult to predict how events such as global climate change will affect the balance between autotrophic and heterotrophic activities in protist communities. To address open questions regarding how protist metabolic versatility is influenced by their environment, we characterized the potential for carbon fixation versus organic carbon degradation using enzymatic assays (RubisCO and β-D-glucosaminidase, respectively) within the water columns of ice-covered lakes in McMurdo Dry Valleys (MDV), Antarctica. Steep physical and chemical gradients in the water columns, microorganism domination and minimal allochthonous inputs makes the MDV lakes uniquely suited to investigate environment-microbe interactions. Spatial trends in RubisCO and β-D-glucosaminidase activities were lake-specific and vertically stratified within the water columns. Moreover, bottom-up drivers controlling the activity of C-fixation vs. organic C-degradation among the MDV protist communities were distinct between the upper photic vs. the deep, aphotic zones. We conclude that differential controls over major C-cycling enzymes have important implications on the influence of environmental change on the carbon and nutrient cycles in the MDV lakes.

10aAntarctic lakes10aAquatic protists10aAutotrophy10aHeterotrophy10aMcMurdo Dry Valleys10aRubisCO10aβ-D-glucosaminidase1 aLi, Wei1 aDolhi-Binder, J1 aCariani, ZE1 aMorgan-Kiss, Rachael, M. uhttps://www.int-res.com/abstracts/ame/v82/n3/p225-239/02158nas a2200229 4500008004100000245010300041210006900144260003900213490000900252520137700261653001001638653002801648653003801676653002401714653001901738653001801757653002301775653001601798100001601814700002901830856006901859 2019 eng d00aImpact of simulated polar night on Antarctic mixotrophic and strict photoautotrophic phytoplankton0 aImpact of simulated polar night on Antarctic mixotrophic and str aOxford, OHbMiami Universityc20180 vM.S.3 a

Phytoplankton in polar regions experience long periods of continuous darkness annually during the polar night. Due to difficulties in performing field work during this period, it is largely unknown how phytoplankton endure this extreme transition from 24-hour daylight in the fall to several months of total darkness in the austral winter. The primary goal of this study was to compare physiological and photosynthetic responses of several Antarctic phytoplankton of variable trophic abilities (pure photosynthetic vs. mixotrophic) to simulated polar night conditions, including the transition seasons before and after winter. Two distinct responses were observed to extended darkness: (1) strict photoautotrophs (Chlamydomonas sp. ICE-MDV and Chlamydomonas sp. UWO241) exhibited functional downregulation their photosynthetic processes in the winter, followed by a lag phase of several days during mimicked spring, and (2) mixotrophs (Isochrysis sp. MDV and Geminigera cryophila) maintained functional photosynthetic apparatus, increased heterotrophy through the winter, and exhibited immediate growth upon return to light incubation. These differing responses to mimicked polar night conditions could represent two different strategies for surviving the long period of darkness in the phytoplankton’s natural environment.

10aalgae10aAntarctic phytoplankton10achlorophyll fluorescence analysis10aMcMurdo Dry Valleys10aPhotosynthesis10aphytoplankton10apolar microbiology10apolar night1 aCariani, ZE1 aMorgan-Kiss, Rachael, M. uhttp://rave.ohiolink.edu/etdc/view?acc_num=miami154720459996908101860nas 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/10.1029/2017JF00458902006nas a2200133 4500008004100000245016300041210006900204260003900273490000900312520143800321100001501759700002901774856006901803 2018 eng d00aAntarctic Chlamydomonas strains C. sp. UWO241 and ICE-MDV exhibit differential restructuring of the photosynthetic apparatus in response to iron0 aAntarctic iChlamydomonasi strains iCi sp UWO241 and ICEMDV exhib aOxford, OHbMiami Universityc20180 vM.S.3 a

As an integral cofactor for many redox-associated processes, iron (Fe) homeostasis is crucial in order to produce sufficient energy for the organism. Fe limitation, or excess, can cause major alterations in the function and structure of the photosynthetic apparatus. Photosynthetic psychrophiles grown under permanent low temperatures exhibit novel adaptations in their photosynthetic apparatus to deal with this permanent stress. The ice-covered lakes of the McMurdo Dry Valleys harbor many species of cold-adapted algae, including Chlamydomonas sp. UWO241 (UWO241). As a consequence of adaptation to multiple permanent extreme conditions, UWO241 exhibits a remodeled photosynthetic apparatus for maintaining redox poise. One unusual characteristic of UWO241 is the absence of a PSI-associated 77K fluorescence emission under a wide range of growth conditions. This phenotype resembles Fe deficiency in other model organisms such as C. reinhardtii. We hypothesized that adaptation to permanent iron deficiency in its native environment may contribute to this unusual phenotype. We compared the effect of Fe availability on the physiology and photobiology of UWO241 with the model C. reinhardtii as well as a second psychrophilic alga, Chlamydomonas sp. ICE-MDV (ICE). The impacts of a restructured photosynthetic apparatus on the unique Fe-associated phenotype in UWO241 will be discussed.

1 aCook, Greg1 aMorgan-Kiss, Rachael, M. uhttp://rave.ohiolink.edu/etdc/view?acc_num=miami152545562177883610050nas a2202965 4500008004100000245007300041210006900114260001200183300001200195490000700207520154900214653001701763653001101780653001201791653002101803653001301824653001301837100002001850700002201870700001601892700002201908700002301930700001701953700002801970700002001998700002502018700001802043700002402061700001602085700002202101700002002123700002702143700002002170700002202190700002302212700003102235700002002266700002302286700002702309700002202336700002702358700002702385700001602412700001902428700002302447700002102470700002202491700001802513700002302531700002802554700002502582700002302607700002002630700002902650700002502679700002002704700002602724700002602750700001702776700002402793700002502817700002302842700002202865700001902887700002002906700002102926700002202947700002102969700001802990700001703008700002203025700001703047700002503064700001903089700002603108700002203134700001903156700002103175700001903196700002703215700003003242700002403272700002403296700001703320700002303337700003203360700002103392700002403413700002203437700002903459700001403488700003103502700002303533700001903556700002303575700002603598700001803624700002103642700001603663700001803679700002403697700002103721700002003742700001903762700001703781700001903798700002103817700002003838700002603858700002003884700002003904700002003924700002503944700002003969700002703989700002404016700003304040700001804073700001504091700002304106700002204129700002004151700001704171700002404188700001804212700002404230700002104254700002204275700002104297700002004318700002004338700002804358700002604386700001704412700002104429700001904450700002304469700003104492700002604523700002004549700002704569700002204596700002104618700002204639700002004661700002804681700001804709700002204727700002604749700002004775700001904795700002404814700001804838700002404856700002604880700001804906700002304924700002504947700002804972700002205000700002505022700001505047700001705062700001505079700003105094700001905125700001805144700002605162700002405188700001905212700001805231700002205249700002605271700002405297700002005321700002405341700002105365700002905386700002105415700002205436700002005458700001905478700002405497700002505521700002105546700002805567700001905595700002205614700001505636700002605651700002105677700002105698700002505719700002205744700001905766700002805785700002305813700002605836700002105862700002105883700002705904700002805931700002105959700001905980700001905999700003006018700002106048700002406069700003206093700003606125700001806161700001606179700002206195700002306217700001906240700001806259700001506277700002106292700002606313700003306339700001706372700002006389700002106409700002406430700002106454700002206475700001906497700002306516700002106539700001806560700002806578700003406606700002406640700002106664700001806685700002006703700003206723700002606755700002706781700002906808700003106837700002106868700002306889700002506912700002106937700002306958700002506981700001607006856006207022 2018 eng d00aBioTIME: A database of biodiversity time series for the Anthropocene0 aBioTIME A database of biodiversity time series for the Anthropoc c07/2018 a760-7860 v273 a

Motivation: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene.

Main types of variables included: The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record.

Spatial location and grain: BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2). Time period and grain BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year.

Major taxa and level of measurement: BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.

Software format: .csv and .SQL.

10abiodiversity10aglobal10aspatial10aspecies richness10atemporal10aturnover1 aDornelas, Maria1 aAntão, Laura, H.1 aMoyes, Faye1 aBates, Amanda, E.1 aMagurran, Anne, E.1 aAdam, Dušan1 aAkhmetzhanova, Asem, A.1 aAppeltans, Ward1 aArcos, José, Manuel1 aArnold, Haley1 aAyyappan, Narayanan1 aBadihi, Gal1 aBaird, Andrew, H.1 aBarbosa, Miguel1 aBarreto, Tiago, Egydio1 aBässler, Claus1 aBellgrove, Alecia1 aBelmaker, Jonathan1 aBenedetti-Cecchi, Lisandro1 aBett, Brian, J.1 aBjorkman, Anne, D.1 aBłażewicz, Magdalena1 aBlowes, Shane, A.1 aBloch, Christopher, P.1 aBonebrake, Timothy, C.1 aBoyd, Susan1 aBradford, Matt1 aBrooks, Andrew, J.1 aBrown, James, H.1 aBruelheide, Helge1 aBudy, Phaedra1 aCarvalho, Fernando1 aCastañeda-Moya, Edward1 aChen, Chaolun, Allen1 aChamblee, John, F.1 aChase, Tory, J.1 aCollier, Laura, Siegwart1 aCollinge, Sharon, K.1 aCondit, Richard1 aCooper, Elisabeth, J.1 aCornelissen, Hans, C.1 aCotano, Unai1 aCrow, Shannan, Kyle1 aDamasceno, Gabriella1 aDavies, Claire, H.1 aDavis, Robert, A.1 aDay, Frank, P.1 aDegraer, Steven1 aDoherty, Tim, S.1 aDunn, Timothy, E.1 aDurigan, Giselda1 aDuffy, Emmett1 aEdelist, Dor1 aEdgar, Graham, J.1 aElahi, Robin1 aElmendorf, Sarah, C.1 aEnemar, Anders1 aErnest, S., K. Morgan1 aEscribano, Rubén1 aEstiarte, Marc1 aEvans, Brian, S.1 aFan, Tung-Yung1 aFarah, Fabiano, Turini1 aFernandes, Luiz, Loureiro1 aFarneda, Fábio, Z.1 aFidelis, Alessandra1 aFitt, Robert1 aFosaa, Anna, Maria1 aFranco, Geraldo, Antonio Da1 aFrank, Grace, E.1 aFraser, William, R.1 aGarcía, Hernando1 aGatti, Roberto, Cazzolla1 aGivan, Or1 aGorgone-Barbosa, Elizabeth1 aGould, William, A.1 aGries, Corinna1 aGrossman, Gary, D.1 aGutierréz, Julio, R.1 aHale, Stephen1 aHarmon, Mark, E.1 aHarte, John1 aHaskins, Gary1 aHenshaw, Donald, L.1 aHermanutz, Luise1 aHidalgo, Pamela1 aHiguchi, Pedro1 aHoey, Andrew1 aVan Hoey, Gert1 aHofgaard, Annika1 aHoleck, Kristen1 aHollister, Robert, D.1 aHolmes, Richard1 aHoogenboom, Mia1 aHsieh, Chih-hao1 aHubbell, Stephen, P.1 aHuettmann, Falk1 aHuffard, Christine, L.1 aHurlbert, Allen, H.1 aIvanauskas, Natália, Macedo1 aJaník, David1 aJandt, Ute1 aJażdżewska, Anna1 aJohannessen, Tore1 aJohnstone, Jill1 aJones, Julia1 aJones, Faith, A. M.1 aKang, Jungwon1 aKartawijaya, Tasrif1 aKeeley, Erin, C.1 aKelt, Douglas, A.1 aKinnear, Rebecca1 aKlanderud, Kari1 aKnutsen, Halvor1 aKoenig, Christopher, C.1 aKortz, Alessandra, R.1 aKrál, Kamil1 aKuhnz, Linda, A.1 aKuo, Chao-Yang1 aKushner, David, J.1 aLaguionie-Marchais, Claire1 aLancaster, Lesley, T.1 aLee, Cheol, Min1 aLefcheck, Jonathan, S.1 aLévesque, Esther1 aLightfoot, David1 aLloret, Francisco1 aLloyd, John, D.1 aLópez-Baucells, Adrià1 aLouzao, Maite1 aMadin, Joshua, S.1 aMagnússon, Borgþór1 aMalamud, Shahar1 aMatthews, Iain1 aMcFarland, Kent, P.1 aMcGill, Brian1 aMcKnight, Diane, M.1 aMcLarney, William, O.1 aMeador, Jason1 aMeserve, Peter, L.1 aMetcalfe, Daniel, J.1 aMeyer, Christoph, F. J.1 aMichelsen, Anders1 aMilchakova, Nataliya1 aMoens, Tom1 aMoland, Even1 aMoore, Jon1 aMoreira, Carolina, Mathias1 aMüller, Jörg1 aMurphy, Grace1 aMyers-Smith, Isla, H.1 aMyster, Randall, W.1 aNaumov, Andrew1 aNeat, Francis1 aNelson, James, A.1 aNelson, Michael, Paul1 aNewton, Stephen, F.1 aNorden, Natalia1 aOliver, Jeffrey, C.1 aOlsen, Esben, M.1 aOnipchenko, Vladimir, G.1 aPabis, Krzysztof1 aPabst, Robert, J.1 aPaquette, Alain1 aPardede, Sinta1 aPaterson, David, M.1 aPélissier, Raphaël1 aPeñuelas, Josep1 aPérez-Matus, Alejandro1 aPizarro, Oscar1 aPomati, Francesco1 aPost, Eric1 aPrins, Herbert, H. T.1 aPriscu, John, C.1 aProvoost, Pieter1 aPrudic, Kathleen, L.1 aPulliainen, Erkki1 aRamesh, B., R.1 aRamos, Olivia, Mendivil1 aRassweiler, Andrew1 aRebelo, Jose, Eduardo1 aReed, Daniel, C.1 aReich, Peter, B.1 aRemillard, Suzanne, M.1 aRichardson, Anthony, J.1 aRichardson, Paul1 avan Rijn, Itai1 aRocha, Ricardo1 aRivera-Monroy, Victor, H.1 aRixen, Christian1 aRobinson, Kevin, P.1 aRodrigues, Ricardo, Ribeiro1 aRossa-Feres, Denise, de Cerquei1 aRudstam, Lars1 aRuhl, Henry1 aRuz, Catalina, S.1 aSampaio, Erica, M.1 aRybicki, Nancy1 aRypel, Andrew1 aSal, Sofia1 aSalgado, Beatriz1 aSantos, Flavio, A. M.1 aSavassi-Coutinho, Ana, Paula1 aScanga, Sara1 aSchmidt, Jochen1 aSchooley, Robert1 aSetiawan, Fakhrizal1 aShao, Kwang-Tsao1 aShaver, Gaius, R.1 aSherman, Sally1 aSherry, Thomas, W.1 aSiciński, Jacek1 aSievers, Caya1 ada Silva, Ana, Carolina1 ada Silva, Fernando, Rodrigues1 aSilveira, Fabio, L.1 aSlingsby, Jasper1 aSmart, Tracey1 aSnell, Sara, J.1 aSoudzilovskaia, Nadejda, A.1 aSouza, Gabriel, B. G.1 aSouza, Flaviana, Maluf1 aSouza, Vinícius, Castro1 aStallings, Christopher, D.1 aStanforth, Rowan1 aStanley, Emily, H.1 aSterza, José, Mauro1 aStevens, Maarten1 aStuart-Smith, Rick1 aSuarez, Yzel, Rondon1 aSupp, Sarah uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/geb.1272902931nas a2200205 4500008004100000245011300041210006900154260001200223490000600235520222200241100002202463700002402485700002402509700002302533700002402556700002102580700002102601700003302622856007002655 2018 eng d00aLocal and Regional Scale Heterogeneity Drive Bacterial Community Diversity and Composition in a Polar Desert0 aLocal and Regional Scale Heterogeneity Drive Bacterial Community c08/20180 v93 a

The distribution of organisms in an environment is neither uniform nor random but is instead spatially patterned. The factors that control this patterning are complex and the underlying mechanisms are poorly understood. Soil microbes are critical to ecosystem function but exhibit highly complex distributions and community dynamics due in large part to the scale-dependent effects of environmental heterogeneity. To better understand the impact of environmental heterogeneity on the distribution of soil microbes, we sequenced the 16S rRNA gene from bacterial communities in the microbe-dominated polar desert ecosystem of the McMurdo Dry Valleys (MDV), Antarctica. Significant differences in key edaphic variables and alpha diversity were observed among the three lake basins of the Taylor Valley (Kruskal–Wallis; pH: χ2 = 68.89, P < 0.001, conductivity: χ2 = 35.03, P < 0.001, observed species: χ2 = 7.98, P = 0.019 and inverse Simpson: χ2 = 18.52, P < 0.001) and each basin supported distinctive microbial communities (ANOSIM R = 0.466, P = 0.001, random forest ratio of 14.1). However, relationships between community structure and edaphic characteristics were highly variable and contextual, ranging in magnitude and direction across regional, basin, and local scales. Correlations among edaphic factors (pH and soil conductivity) and the relative abundance of specific phyla were most pronounced along local environmental gradients in the Lake Fryxell basin where Acidobacteria, Bacteroidetes, and Proteobacteria declined while Deinococcus–Thermus and Gemmatimonadetes increased with soil conductivity (all P < 0.1). Species richness was most strongly related to the soil conductivity gradient present within this study system. We suggest that the relative importance of pH versus soil conductivity in structuring microbial communities is related to the length of edaphic gradients and the spatial scale of sampling. These results highlight the importance of conducting studies over large ranges of key environmental gradients and across multiple spatial scales to assess the influence of environmental heterogeneity on the composition and diversity of microbial communities.

1 aFeeser, Kelli, L.1 aVan Horn, David, J.1 aBuelow, Heather, N.1 aColman, Daniel, R.1 aMcHugh, Theresa, A.1 aOkie, Jordan, G.1 aSchwartz, Egbert1 aTakacs-Vesbach, Cristina, D. uhttps://www.frontiersin.org/article/10.3389/fmicb.2018.01928/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.1495302880nas a2200625 4500008004100000245007400041210006900115260001200184490000800196520106500204100002301269700002101292700002101313700001601334700001801350700002301368700002201391700002301413700002201436700002001458700002701478700002001505700002301525700002801548700002301576700002201599700002101621700002401642700002001666700002401686700001601710700001501726700001801741700002201759700002701781700001901808700002401827700002201851700002101873700002801894700002201922700002201944700001701966700002101983700001902004700002202023700001802045700002702063700002302090700002302113700002202136700001602158700003202174856004802206 2017 eng d00aA communal catalogue reveals Earth’s multiscale microbial diversity0 acommunal catalogue reveals Earth s multiscale microbial diversit c11/20170 v5513 a

Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth’s microbial diversity.

1 aThompson, Luke, R.1 aSanders, Jon, G.1 aMcDonald, Daniel1 aAmir, Amnon1 aLadau, Joshua1 aLocey, Kenneth, J.1 aPrill, Robert, J.1 aTripathi, Anupriya1 aGibbons, Sean, M.1 aAckermann, Gail1 aNavas-Molina, Jose, A.1 aJanssen, Stefan1 aKopylova, Evguenia1 aVázquez-Baeza, Yoshiki1 aGonzález, Antonio1 aMorton, James, T.1 aMirarab, Siavash1 aXu, Zhenjiang, Zech1 aJiang, Lingjing1 aHaroon, Mohamed, F.1 aKanbar, Jad1 aZhu, Qiyun1 aSong, Se, Jin1 aKosciolek, Tomasz1 aBokulich, Nicholas, A.1 aLefler, Joshua1 aBrislawn, Colin, J.1 aHumphrey, Gregory1 aOwens, Sarah, M.1 aHampton-Marcell, Jarrad1 aBerg-Lyons, Donna1 aMcKenzie, Valerie1 aFierer, Noah1 aFuhrman, Jed, A.1 aClauset, Aaron1 aStevens, Rick, L.1 aShade, Ashley1 aPollard, Katherine, S.1 aGoodwin, Kelly, D.1 aJansson, Janet, K.1 aGilbert, Jack, A.1 aKnight, Rob1 aConsortium, The, Earth Micr uhttps://www.nature.com/articles/nature2462101933nas a2200181 4500008004100000245012100041210006900162260001200231490000600243520129900249100002001548700001901568700002101587700002001608700002501628700002501653856007301678 2017 eng d00aDiversity and Distribution of Freshwater Aerobic Anoxygenic Phototrophic Bacteria across a Wide Latitudinal Gradient0 aDiversity and Distribution of Freshwater Aerobic Anoxygenic Phot c02/20170 v83 a

Aerobic anoxygenic phototrophs (AAPs) have been shown to exist in numerous marine and brackish environments where they are hypothesized to play important ecological roles. Despite their potential significance, the study of freshwater AAPs is in its infancy and limited to local investigations. Here, we explore the occurrence, diversity and distribution of AAPs in lakes covering a wide latitudinal gradient: Mongolian and German lakes located in temperate regions of Eurasia, tropical Great East African lakes, and polar permanently ice-covered Antarctic lakes. Our results show a widespread distribution of AAPs in lakes with contrasting environmental conditions and confirm that this group is composed of different members of the Alpha- and Betaproteobacteria. While latitude does not seem to strongly influence AAP abundance, clear patterns of community structure and composition along geographic regions were observed as indicated by a strong macro-geographical signal in the taxonomical composition of AAPs. Overall, our results suggest that the distribution patterns of freshwater AAPs are likely driven by a combination of small-scale environmental conditions (specific of each lake and region) and large-scale geographic factors (climatic regions across a latitudinal gradient).

1 aFerrera, Isabel1 aSarmento, Hugo1 aPriscu, John, C.1 aChiuchiolo, Amy1 aGonzález, José, M.1 aGrossart, Hans-Peter uhttp://journal.frontiersin.org/article/10.3389/fmicb.2017.00175/full02077nas 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-w02308nas a2200217 4500008004100000022001400041245010100055210006900156260001200225300001400237490000700251520161900258100002501877700001601902700002001918700002201938700002401960700001801984700002402002856006402026 2017 eng d a0722-406000aFreshwater diatom biogeography and the genus Luticola: an extreme case of endemism in Antarctica0 aFreshwater diatom biogeography and the genus Luticola an extreme c03/2017 a1185-11960 v403 a

Historical views have characterized Antarctica as a frozen desert with low diversity, although recent studies suggest that this may not be true for microscopic organisms. For microbes, assessing endemism in the Antarctic region has been particularly important, especially against a backdrop of debate regarding their presumed cosmopolitan nature. To contribute to this conversation, we highlight the observed endemism of the freshwater diatom genus Luti- cola in Antarctica by synthesizing the results of a modern high-resolution taxonomy from the Continental, Maritime, and sub-Antarctic regions. We report that Luticola has one of the highest endemic rates of any diatom genus in Antarctica, in terms of total number of species (taxon endemism) and percentage of the entire genus (phylogenetic endemism). Of the over 200 species of Luticola globally, nearly 20% (43) occur in the Antarctic, with 42 of these being endemic. Within regions, Maritime Antarctica has the largest number of Luticola species and endemics (28 and 23, respectively), followed by Continental Antarctica (14, 9) and sub-Antarctic islands (8, 6). Thus, 38 of the 42 endemics are found in a single region only. While the timing of Luticola diversi cation has not been established, fossil evidence suggests recent invasions and/or diversi cation over a relatively short geologic timescale. Understanding the origin and evolution of endemic diatom species in Antarctica will help us better understand microbial biogeography, as well as assess and interpret impacts of large-scale environmental change taking place at southern latitudes.

1 aKociolek, J. Patrick1 aKopalova, K1 aHamsher, S., E.1 aKohler, Tyler, J.1 aVan de Vijver, Bart1 aConvey, Peter1 aMcKnight, Diane, M. uhttps://link.springer.com/article/10.1007/s00300-017-2090-701407nas 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/abstract01022nas a2200289 4500008004100000245010700041210006900148260001200217300001400229490000700243100002800250700002200278700002500300700001900325700002000344700002700364700002500391700002600416700002300442700001700465700001900482700002000501700002100521700001800542700002100560856015100581 2016 eng d00aBiogeochemistry and microbial diversity in the marine cavity beneath the McMurdo Ice Shelf, Antarctica0 aBiogeochemistry and microbial diversity in the marine cavity ben c11/2015 a572 - 5860 v611 aVick-Majors, Trista, J.1 aAchberger, Amanda1 aSantibáñez, Pamela1 aDore, John, E.1 aHodson, Timothy1 aMichaud, Alexander, B.1 aChristner, Brent, C.1 aAi, Jill., Mikucki Ji1 aSkidmore, Mark, L.1 aPowell, Ross1 aAdkins, Peyton1 aBarbante, Carlo1 aMitchell, Andrew1 aScherer, Reed1 aPriscu, John, C. uhttp://doi.wiley.com/10.1002/lno.v61.2http://doi.wiley.com/10.1002/lno.10234http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Flno.1023400694nas 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-2015-019402462nas a2200193 4500008004100000022001300041245008800054210006900142260001600211300001400227490000800241520184200249100002102091700002202112700002302134700002502157700001502182856007102197 2016 eng d a0921818100aLake Vanda: A sentinel for climate change in the McMurdo Sound Region of Antarctica0 aLake Vanda A sentinel for climate change in the McMurdo Sound Re cJan-09-2016 a213 - 2270 v1443 a

Lake Vanda is a perennially ice-covered, meromictic, endorheic lake located in the McMurdo Dry Valleys of Antarctica, and an exceptional sentinel of climate change within the region. Lake levels rose 15 m over the past 68 years in response to climate-driven variability in ice-cover sublimation, meltwater production, and annual discharge of the Onyx River, the main source of water to the lake. Evidence from a new bathymetric map and water balance model combined with annual growth laminations in benthic mats suggest that the most recent filling trend began abruptly 80 years ago, in the early 1930s. This change increased lake volume by > 50%, triggered the formation of a new, upper, thermohaline convection cell, and cooled the lower convection cell by at least 2 °C and the bottom-most waters by at > 4 °C. Additionally, the depth of the deep chlorophyll a maximum rose by > 2 m, and deep-growing benthic algal mats declined while shallow benthic mats colonized freshly inundated areas. We attribute changes in hydrology to regional variations in air flow related to the strength and position of the Amundsen Sea Low (ASL) pressure system which have increased the frequency of down-valley, föhn winds associated with surface air temperature warming in the McMurdo Dry Valleys. The ASL has also been implicated in the recent warming of the Antarctic Peninsula, and provides a common link for climate-related change on opposite sides of the continent. If this trend persists, Lake Vanda should continue to rise and cool over the next 200 years until a new equilibrium lake level is achieved. Most likely, future lake rise will lead to isothermal conditions not conducive to thermohaline convection, resulting in a drastically different physical, biogeochemical, and biological structure than observed today.

1 aCastendyk, Devin1 aObryk, Maciek, K.1 aLeidman, Sasha, Z.1 aGooseff, Michael, N.1 aHawes, Ian uhttp://www.sciencedirect.com/science/article/pii/S092181811530014X00604nas a2200169 4500008004100000245007900041210006900120260001600189490000600205100002200211700002500233700002700258700002100285700002300306700002800329856007700357 2016 eng d00aMicrobial Community Structure of Subglacial Lake Whillans, West Antarctica0 aMicrobial Community Structure of Subglacial Lake Whillans West A cOct-09-20170 v71 aAchberger, Amanda1 aChristner, Brent, C.1 aMichaud, Alexander, B.1 aPriscu, John, C.1 aSkidmore, Mark, L.1 aVick-Majors, Trista, J. uhttp://journal.frontiersin.org/Article/10.3389/fmicb.2016.01457/abstract01330nas a2200193 4500008004100000245009800041210006900139260004000208490000900248520071900257653001500976653001400991653001501005653001701020653001901037100002101056700002101077856003801098 2016 eng d00aNoble Gas Radioisotope Constraints on Water Residence Time and Solvent Sources in Lake Bonney0 aNoble Gas Radioisotope Constraints on Water Residence Time and S aChicago, ILbUniversity of Illinois0 vM.S.3 a

A noble gas radionuclide analysis of perennially ice covered West Lake Bonney was performed in order to determine water residence time and ice cover timing. Bulk gas samples were collected at four depths in the lake. Krypton and argon gases were selectively isolated from the bulk gas and measurements of 81Kr, 85Kr and 39Ar were made. Radiokrypton and radioargon analyses yielded lower limit ages of 78 to 285 years, significantly younger than expected based on previous dating efforts. It was determined that these new data do not invalidate previous work, but instead offer new insight into the timing of the most recent episode of direct communication between the atmosphere and West Lake Bonney waters.

10aAntarctica10anoble gas10aradioargon10aradiokrypton10aresidence time1 aCronin, Kyle, D.1 aDoran, Peter, T. uhttp://hdl.handle.net/10027/2157002226nas 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/fiw14800836nas a2200229 4500008004100000245007200041210006900113260001600182490000600198100002800204700002100232700002200253700002500275700001900300700002700319700002200346700002400368700002300392700002100415710002900436856014100465 2016 eng d00aPhysiological Ecology of Microorganisms in Subglacial Lake Whillans0 aPhysiological Ecology of Microorganisms in Subglacial Lake Whill cMar-10-20180 v71 aVick-Majors, Trista, J.1 aMitchell, Andrew1 aAchberger, Amanda1 aChristner, Brent, C.1 aDore, John, E.1 aMichaud, Alexander, B.1 aMikucki, Jill, A.1 aPurcell, Alicia, M.1 aSkidmore, Mark, L.1 aPriscu, John, C.1 aThe WISSARD Science Team uhttp://journal.frontiersin.org/article/10.3389/fmicb.2016.01705/fullhttp://journal.frontiersin.org/article/10.3389/fmicb.2016.01705/full08594nas 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/plain00932nas a2200265 4500008004100000022001400041245013400055210006900189260001200258300001400270490000800284100002300292700002800315700001600343700002000359700002500379700002200404700002100426700001700447700002300464700002200487700002400509700001600533856011700549 2015 eng d a0029-854900aGlobal environmental change and the nature of aboveground net primary productivity responses: insights from long-term experiments0 aGlobal environmental change and the nature of aboveground net pr c04/2015 a935 - 9470 v1771 aSmith, Melinda, D.1 aLa Pierre, Kimberly, J.1 aCollins, SL1 aKnapp, Alan, K.1 aGross, Katherine, L.1 aBarrett, John, E.1 aFrey, Serita, D.1 aGough, Laura1 aMiller, Robert, J.1 aMorris, James, T.1 aRustad, Lindsey, E.1 aYarie, John uhttp://link.springer.com/10.1007/s00442-015-3230-9http://link.springer.com/content/pdf/10.1007/s00442-015-3230-900637nas a2200193 4500008004100000022001300041245008600054210006900140260001200209300001200221490000800233100002000241700002100261700002300282700002400305700002600329700002200355856006600377 2015 eng d a0304380000aLinking management to biodiversity in built ponds using metacommunity simulations0 aLinking management to biodiversity in built ponds using metacomm c01/2015 a36 - 450 v2961 aSokol, Eric, R.1 aBrown, Bryan, L.1 aCarey, Cayelan, C.1 aTornwall, Brett, M.1 aSwan, Christopher, M.1 aBarrett, John, E. uhttp://linkinghub.elsevier.com/retrieve/pii/S030438001400491802538nas a2200205 4500008004100000245010400041210006900145260001200214300001200226490000700238520189000245100002202135700002102157700001902178700001302197700001602210700001702226700002402243856006502267 2015 eng d00a Long-Term Hydrologic Control of Microbial Mat Abundance in McMurdo Dry Valley Streams, Antarctica.0 aLongTerm Hydrologic Control of Microbial Mat Abundance in McMurd c03/2015 a310-3270 v183 a

Given alterations in global hydrologic regime, we examine the role of hydrology in regulating stream microbial mat abundance in the McMurdo Dry Valleys, Antarctica. Here, perennial mats persist as a desiccated crust until revived by summer streamflow, which varies inter-annually, and has increased since the 1990s. We predicted high flows to scour mats, and intra-seasonal drying to slow growth. Responses were hypothesized to differ based on mat location within streams, along with geomorphology, which may promote (high coverage) or discourage (low coverage) accrual. We compared hydrologic trends with the biomass of green and orange mats, which grow in the channel, and black mats growing at stream margins for 16 diverse stream transects over two decades. We found mat biomass collectively decreased during first decade coinciding with low flows, and increased following elevated discharges. Green mat biomass showed the greatest correlations with hydrology and was stimulated by discharge in high coverage transects, but negatively correlated in low coverage due to habitat scour. In contrast, orange mat biomass was negatively related to flow in high coverage transects, but positively correlated in low coverage because of side-channel expansion. Black mats were weakly correlated with all hydrologic variables regardless of coverage. Lastly, model selection indicated the best combination of predictive hydrologic variables for biomass differed between mat types, but also high and low coverage transects. These results demonstrate the importance of geomorphology and species composition to modeling primary production, and will be useful in predicting ecological responses of benthic habitats to altered hydrologic regimes.

1 aKohler, Tyler, J.1 aStanish, Lee, F.1 aCrisp, Stenven1 aKoch, J.1 aLiptzin, D.1 aBaeseman, J.1 aMcKnight, Diane, M. uhttp://link.springer.com/article/10.1007%2Fs10021-014-9829-600801nas a2200253 4500008004100000022001400041245008400055210006900139260001200208300000800220490000700228100003400235700002400269700002200293700002600315700002500341700002400366700001700390700002200407700002300429700002600452700002200478856004700500 2015 eng d a1445-522600aMitochondrial DNA analyses reveal widespread tardigrade diversity in Antarctica0 aMitochondrial DNA analyses reveal widespread tardigrade diversit c12/2015 a5780 v291 aVelasco-Castrillon, Alejandro1 aMcInnes, Sandra, J.1 aSchultz, Mark, B.1 aArroniz-Crespo, Maria1 aD'Haese, Cyrille, A.1 aGibson, John, A. E.1 aAdams, Byron1 aPage, Timothy, J.1 aAustin, Andrew, D.1 aCooper, Steven, J. B.1 aStevens, Mark, I. uhttp://www.publish.csiro.au/?paper=IS1401900864nas 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.1035202661nas a2200145 4500008004100000245006100041210006000102260004000162300000800202490000700210520218500217100002202402700002402424856006702448 2015 eng d00aQuantifying long-term geomorphology of Antarctic streams0 aQuantifying longterm geomorphology of Antarctic streams aBoulder, CObUniversity of Colorado a1850 vMS3 a

 

In 1994, 16 stream transects were established in the McMurdo Dry Valleys of Antarctica beginning a long term data set characterizing microbial communities and channel geometry. The transects were established to record microbial mat dynamics and stream geomorphology. To accomplish this, the transects were surveyed for points of interest outside and inside the stream channel. Beginning in 2010 the microbial surveys received ground based LiDAR support. This allowed for greater resolution in mapping and analyzing stream morphology than traditional surveying methods. The purpose of this study was to overlap the traditional methods of surveying individual points of interest with a data cloud representing the entire stream transect to be able to continue the microbial study into the future unabated. Using surveyed microbial mats as an indicator of a location in time, a history of channel elevations was created for 7 transects. In general, the streams have not changed significantly in the 20 year record, with exceptions being the steep channel of Bohner Stream, and Huey Creek, which receives large sediment loads from the sharply incised upstream channel, both of which saw large variations in maximum bed change exceeding 75cm and 150 cm respectively. In addition to creating an elevation history, relative bed change was plotted against the ash free dry mass of the microbial mats sampled to determine the resilience of the mats. It was found that microbial mats are more abundant in areas of near zero change. The four microbial mats studied however, which include green, black, orange, and red mats, differed greatly in adaptability with regards to bed change. Green microbial mats, which are typically hidden under large immobile rocks, were not often found in areas with any significant bed change. Conversely, orange mats were found in the most dynamic parts of the stream bed with outliers seen in areas with change exceeding 50 cm with. Finally black microbial mats had the largest values of ash free dry mass indicating the largest resilience to the scouring effects of high flow.

 

1 aCrisp, Steven, W.1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/1727444346?accountid=1450304908nas 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/plain04273nas a2200193 4500008004100000022001400041245007400055210006900129260001600198300001400214490000700228520366500235100002203900700002103922700002503943700002203968700002403990856006504014 2015 eng d a0954-102000aRecovery of Antarctic stream epilithon from simulated scouring events0 aRecovery of Antarctic stream epilithon from simulated scouring e cJan-08-2015 a341 - 3540 v273 a

Microbial mats are common in polar streams and often dominate benthic biomass. Climate change may be enhancing the variability of stream flows in the Antarctic, but so far studies investigating mat responses to disturbance have been limited in this region. Mat regrowth was evaluated following disturbance by experimentally scouring rocks from an ephemeral McMurdo Dry Valley stream over two summers (2001–02 and 2012–13). Mats were sampled at the beginning and resampled at the end of the flow season. In 2012–13, mats were additionally resampled mid-season along with previously undisturbed controls. In 2001–02 rocks regained 47% of chlorophyll aand 40% of ash-free dry mass by the end of the summer, while in 2012–13 rocks regrew 18% and 27%, respectively. Mat stoichiometry differed between summers, and reflected differences in biomass and discharge. Oscillatoria spp. were greatest on scoured rocks and Phormidium spp. on undisturbed rocks. Small diatoms Humidophila andFistulifera spp. increased throughout the summer in all mats, with the latter more abundant in scoured communities. Collectively, these data suggest that mats are variable intra-annually, responsive to hydrology and require multiple summers to regrow initial biomass once lost. These results will aid the interpretation of long-term data, as well as inform Antarctic Specially Managed Area protocols.

1 aKohler, Tyler, J.1 aChatfield, Ethan1 aGooseff, Michael, N.1 aBarrett, John, E.1 aMcKnight, Diane, M. uhttp://www.journals.cambridge.org/abstract_S095410201500002404591nas 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_S095410201400067402755nas 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/art0000202195nas a2200157 4500008004100000245014100041210006900182260001200251300001000263490000700273520155900280100002401839700002101863700002401884856012901908 2014 eng d00aDiel flow pulses drive particulate organic matter transport from microbial mats in a glacial meltwater stream in the McMurdo Dry Valleys0 aDiel flow pulses drive particulate organic matter transport from c01/2014 a86-970 v503 a Many glacial meltwater streams in the McMurdo Dry Valleys (MDV) of Antarctica contain abundant microbial mats, representing hot spots of primary production in a barren landscape. These mats persist through the winter in a freeze-dried state and grow in the summer, experiencing a dynamic hydrologic regime as streamflow varies on a diel cycle and with weather conditions. During diel peaks in flow these streams transport particulate organic matter (POM) to the downstream closed-basin lakes. We investigated the spatial and temporal dynamics of POM transport derived from the scouring of microbial mats in Von Guerard Stream of the MDV. The results show clockwise hysteresis effects in POM concentration over diel flood pulses and suggests that POM transport in the MDVs is supply limited. Further studies are required to confirm this and to identify the potential contributing sources of POM. The hysteresis effect was modeled using an approach derived from models of sediment transport in streams. Spatial variations in POM transport indicate that patch-scale variations in bed shear stress and benthic biomass also influence transport which is integrated downstream over several 100's of meters. Large variations in the POM transport dynamics between different diel flood pulses were found to be related to the time since a resetting flood event and the regrowth of potentially mobile benthic biomass, providing further evidence of the importance of supply limitation and flow variability in controlling the organic matter flux of stream ecosystems.1 aCullis, James, D.S.1 aStanish, Lee, F.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/diel-flow-pulses-drive-particulate-organic-matter-transport-microbial-mats-glacial-meltwater03450nas a2200169 4500008004100000245009600041210006900137260004500206300000800251490001800259520283100277100003003108700001703138700002003155700001803175856008703193 2014 eng d00aElemental Cycling in a Flow-Through Lake in the McMurdo Dry Valleys, Antarctica: Lake Miers0 aElemental Cycling in a FlowThrough Lake in the McMurdo Dry Valle aColumbusbOhio State Universityc06/2014 a1220 vMaster Thesis3 a

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

1 aFair, Alexandria, Corinne1 aLyons, Berry1 aCarey, Anne, E.1 aChin, Yu-Ping uhttps://etd.ohiolink.edu/!etd.send_file?accession=osu1413291502&disposition=inline01873nas 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/emu00402909nas 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/10.1890/12-2216.102237nas 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.pdf02340nas a2200241 4500008004100000245013800041210006900179260001200248300001100260490000600271520148800277100002301765700002401788700002301812700001901835700002001854700002201874700001901896700001701915700001801932700002701950856012101977 2013 eng d00aCharacterization of fulvic acid fractions of dissolved organic matter during ice-out in a hyper-eutrophic, coastal pond in Antarctica0 aCharacterization of fulvic acid fractions of dissolved organic m c12/2013 a0450150 v83 aDissolved humic material (HDOM) is ubiquitous to all natural waters and its source material influences its chemical structure, reactivity, and bioavailability. While terrestrially derived HDOM reference materials distributed by the International Humic Substances Society (IHSS) have been readily available to engineering and scientific communities, a microbially derived reference HDOM was not, despite the well-characterized differences in the chemistry and reactivity of HDOM derived from terrestrial versus microbial sources. To address this gap, we collected a microbial reference fulvic acid from Pony Lake (PLFA) for distribution through the IHSS. Pony Lake is a saline coastal pond on Ross Island, Antarctica, where the landscape is devoid of terrestrial plants. Sample collection occurred over a 17-day period in the summer season at Pony Lake. During this time, the dissolved organic carbon (DOC) concentrations increased nearly two-fold, and the fulvic acid fraction (collected using the XAD-8 method) accounted for 14.6% of the DOC. During the re-concentration and desalting procedures we isolated two other chemically distinct fulvic acid fractions: (1) PLFA-2, which was high in carbohydrates and (2) PLFA-CER, which was high in nitrogen. The chemical characteristics (elemental analysis, optical characterization with UV–vis and fluorescence spectroscopy, and 13C NMR spectroscopy) of the three fulvic acid fractions helped to explain their behavior during isolation.1 aCawley, Kaelin, M.1 aMcKnight, Diane, M.1 aMiller, Penney, L.1 aCory, Rose, M.1 aFimmen, Ryan, L1 aGuerard, Jennifer1 aDieser, Markus1 aJaros, Chris1 aChin, Yu-Ping1 aForeman, Christine, M. uhttps://mcm.lternet.edu/content/characterization-fulvic-acid-fractions-dissolved-organic-matter-during-ice-out-hyper00579nas a2200157 4500008004100000245012400041210006900165260001200234300001600246490000700262100001600269700002500285700002500310700002400335856006200359 2013 eng d00aThe influence of stream thermal regimes and preferential flow paths on hyporheic exchange in a glacial meltwater stream0 ainfluence of stream thermal regimes and preferential flow paths  c09/2013 a5552 - 55690 v491 aCozzetto, K1 aBencala, Kenneth, E.1 aGooseff, Michael, N.1 aMcKnight, Diane, M. uhttp://onlinelibrary.wiley.com/doi/10.1002/wrcr.20410/pdf00643nas a2200169 4500008004100000245010200041210006900143260001200212300001100224490000600235100002000241700002300261700002100284700001900305700002200324856012700346 2013 eng d00aLocal and regional influences over soil microbial metacommunities in the Transantarctic Mountains0 aLocal and regional influences over soil microbial metacommunitie c11/2013 aart1360 v41 aSokol, Eric, R.1 aHerbold, Craig, W.1 aLee, Charles, K.1 aCary, Craig, S1 aBarrett, John, E. uhttps://mcm.lternet.edu/content/local-and-regional-influences-over-soil-microbial-metacommunities-transantarctic-mountains02033nas a2200229 4500008004100000245011500041210006900156260001200225300001100237490000600248520129700254100002701551700001901578700002101597700002901618700002001647700002001667700002301687700001801710700002401728856005101752 2013 eng d00aMicrobial growth under humic-free conditions in a supraglacial stream system on the Cotton Glacier, Antarctica0 aMicrobial growth under humicfree conditions in a supraglacial st c09/2013 a0350220 v83 aDuring the austral summers of 2004 and 2009, we sampled a supraglacial stream on the Cotton Glacier, Antarctica. The stream dissolved organic matter (DOM) was low (44–48 μM C) and lacked detectable humic fluorescence signatures. Analysis of the excitation emissions matrices (EEMs) indicated that amino-acid fluorophores dominated, consistent with DOM of microbial origin, with little humic-like fluorescence. In most aquatic ecosystems, humic DOM attenuates harmful UV radiation and its absence may represent an additional stressor influencing the microbial community. Nonetheless, the stream contained an active microbial assemblage with bacterial cell abundances from 2.94 × 104 to 4.97 × 105 cells ml−1, and bacterial production ranging from 58.8 to 293.2 ng C l−1 d−1. Chlorophyll-a concentrations ranged from 0.3 to 0.53 μg l−1 indicating that algal phototrophs were the probable source of the DOM. Microbial isolates produced a rainbow of pigment colors, suggesting adaptation to stress, and were similar to those from other cryogenic systems (Proteobacteria and Bacteroidetes lineages). Supraglacial streams provide an example of contemporary microbial processes on the glacier surface and a natural laboratory for studying microbial adaptation to the absence of humics.1 aForeman, Christine, M.1 aCory, Rose, M.1 aMorris, Cindy, E1 aSanClements, Michael, D.1 aSmith, Heidi, J1 aLisle, John, T.1 aMiller, Penney, L.1 aChin, Yu-Ping1 aMcKnight, Diane, M. uhttp://iopscience.iop.org/1748-9326/8/3/03502200803nas a2200217 4500008004100000245011600041210006900157260001200226300001400238490000700252100001900259700002700278700001700305700002000322700002400342700002800366700002300394700001800417700002400435856012600459 2013 eng d00aPhysicochemical and biological dynamics in a coastal Antarctic lake as it transitions from frozen to open water0 aPhysicochemical and biological dynamics in a coastal Antarctic l c12/2013 a663–6750 v251 aDieser, Markus1 aForeman, Christine, M.1 aJaros, Chris1 aLisle, John, T.1 aGreenwood, Mark, C.1 aLaybourn-Parry, Johanna1 aMiller, Penney, L.1 aChin, Yu-Ping1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/physicochemical-and-biological-dynamics-coastal-antarctic-lake-it-transitions-frozen-open00753nas a2200193 4500008004100000245014000041210006900181260001200250300000800262490000700270100002100277700002300298700001700321700002500338700002400363700002400387700002200411856012600433 2012 eng d00aAntarctic Tardigrada: a first step in understanding molecular operational taxonomic units (MOTUs) and biogeography of cryptic meiofauna0 aAntarctic Tardigrada a first step in understanding molecular ope c12/2012 a5260 v261 aCzechowski, Paul1 aSands, Chester, J.1 aAdams, Byron1 aD'Haese, Cyrille, A.1 aGibson, John, A. E.1 aMcInnes, Sandra, J.1 aStevens, Mark, I. uhttps://mcm.lternet.edu/content/antarctic-tardigrada-first-step-understanding-molecular-operational-taxonomic-units-motus02734nas 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.full00583nas a2200169 4500008004100000245008400041210006900125260001200194300001400206490000700220100001800227700002100245700002000266700002100286700002900307856007700336 2012 eng d00aEvidence of form II RubisCO ( cbbM) in a perennially ice-covered Antarctic lake0 aEvidence of form II RubisCO cbbM in a perennially icecovered Ant c11/2012 a491 - 5000 v821 aKong, Weidong1 aDolhi, Jenna, M.1 aChiuchiolo, Amy1 aPriscu, John, C.1 aMorgan-Kiss, Rachael, M. uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2012.01431.x/full00684nas a2200193 4500008004100000245011200041210006900153260001200222300001400234490000700248100001800255700002200273700002100295700002100316700002800337700002000365700002800385856007700413 2012 eng d00aMicrobial dynamics and flagellate grazing during transition to winter in Lakes Hoare and Bonney, Antarctica0 aMicrobial dynamics and flagellate grazing during transition to w c11/2012 a449 - 4580 v821 aThurman, Jill1 aParry, Jacqueline1 aHill, Philip, J.1 aPriscu, John, C.1 aVick-Majors, Trista, J.1 aChiuchiolo, Amy1 aLaybourn-Parry, Johanna uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2012.01423.x/full01017nas 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.120860710900621nas a2200181 4500008004100000245010500041210006900146260001200215300001200227490000700239100002000246700002400266700001900290700001700309700002100326700002100347856007100368 2012 eng d00aPerchlorate and chlorate biogeochemistry in ice-covered lakes of the McMurdo Dry Valleys, Antarctica0 aPerchlorate and chlorate biogeochemistry in icecovered lakes of  c12/2012 a19 - 300 v981 aJackson, Andrew1 aDavila, Alfonso, F.1 aEstrada, Nubia1 aLyons, Berry1 aCoates, John, D.1 aPriscu, John, C. uhttp://www.sciencedirect.com/science/article/pii/S001670371200511X01724nam 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/hg97w43588229087/02772nas a2200169 4500008004100000245009200041210006900133260001200202490000800214520222300222100002302445700001502468700001502483700002402498700001502522856006502537 2012 eng d00aSeismic multiplet response triggered by melt at Blood Falls, Taylor Glacier, Antarctica0 aSeismic multiplet response triggered by melt at Blood Falls Tayl c07/20120 v1173 a

Meltwater input often triggers a seismic response from glaciers and ice sheets. It is difficult, however, to measure melt production on glaciers directly, while subglacial water storage is not directly observable. Therefore, we document temporal changes in seismicity from a dry-based polar glacier (Taylor Glacier, Antarctica) during a melt season using a synthesis of seismic observation and melt modeling. We record icequakes using a dense six-receiver network of three-component geophones and compare this with melt input generated from a calibrated surface energy balance model. In the absence of modeled surface melt, we find that seismicity is well-described by a diurnal signal composed of microseismic events in lake and glacial ice. During melt events, the diurnal signal is suppressed and seismicity is instead characterized by large glacial icequakes. We perform network-based correlation and clustering analyses of seismic record sections and determine that 18% of melt-season icequakes are repetitive (multiplets). The epicentral locations for these multiplets suggest that they are triggered by meltwater produced near a brine seep known as Blood Falls. Our observations of the correspondingp-wave first motions are consistent with volumetric source mechanisms. We suggest that surface melt enables a persistent pathway through this cold ice to an englacial fracture system that is responsible for brine release episodes from the Blood Falls seep. The scalar moments for these events suggest that the volumetric increase at the source region can be explained by melt input.

1 aCarmichael, J., D.1 aPettit, E.1 aHoffman, M1 aFountain, Andrew, G1 aHallet, B. uhttp://onlinelibrary.wiley.com/doi/10.1029/2011JF002221/full00682nas a2200169 4500008004100000245014300041210006900184260001200253300001400265490000700279100001800286700001800304700001900322700002400341700002400365856012300389 2011 eng d00a15N and 13C{14N} NMR investigation of the major nitrogen-containing segment in an aquatic fulvic acid: Evidence for a hydantoin derivative0 a15N and 13C 14N NMR investigation of the major nitrogencontainin c12/2011 a775 - 7800 v491 aFang, Xiaowen1 aMao, Jingdong1 aCory, Rose, M.1 aMcKnight, Diane, M.1 aSchmidt-Rohr, Klaus uhttps://mcm.lternet.edu/content/15n-and-13c14n-nmr-investigation-major-nitrogen-containing-segment-aquatic-fulvic-acid00651nas 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-y02193nas a2200145 4500008004100000245014200041210006900183260004000252300000800292490001000300520162300310100002401933700002401957856006601981 2011 eng d00aRemoval of benthic algae in swift-flowing streams: The significance of spatial and temporal variation in shear stress and bed disturbance0 aRemoval of benthic algae in swiftflowing streams The significanc aBoulder, CObUniversity of Colorado a2630 vPh.D.3 a

 

In this thesis I investigate the role of spatial and temporal dynamics of flow, bed shear stress, and bed disturbance on the removal of benthic algal and the consequences for our understanding of the dynamics of stream ecosystems and the transport of organic matter in fluvial systems. I use data obtained from two specific case studies where benthic algal mats are key components in the overall system dynamics. The first case study investigates spatial and temporal variations in particular organic matter transport derived from the removal of benthic algae in a stream in the McMurdo Dry Valleys of Antarctica. The second case study uses a combination of field observations and analysis, one and two dimensional hydraulic modeling, and laboratory flume studies to investigate the controls on the removal of the stalk forming diatom Didymosphenia geminata. The results show that benthic algae growing in swift-flowing streams are well adapted to this environment. Hence the removal of organic material due to elevated shear stress alone is limited and effective control of nuisance blooms of benthic algae such as D. geminata requires flood events sufficiently high enough to results in wide spread disturbance of the stream substrate. These flow requirements are similar to the requirements for channel maintenance flows and could therefore be considered for inclusion in the operating rules for dams in order to maintain the diversity of stream ecosystems and functioning water supply infrastructure.

 

1 aCullis, James, D.S.1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/916604693?accountid=1450300685nam a2200193 4500008004100000020002200041245010600063210006900169260003600238300001400274490000800288100001900296700002500315700002400340700002300364700002600387700002000413856005800433 2011 eng d a978-94-007-1363-500aSpectral Methods to Advance Understanding of Dissolved Organic Carbon Dynamics in Forested Catchments0 aSpectral Methods to Advance Understanding of Dissolved Organic C aDordrechtbSpringer Netherlands a117 - 1350 v2161 aCory, Rose, M.1 aBoyer, Elizabeth, W.1 aMcKnight, Diane, M.1 aLevia, Delphis, F.1 aCarlyle-Moses, Darryl1 aTanaka, Tadashi uhttp://www.springerlink.com/content/lv9365ml54192m29/00776nas a2200229 4500008004100000245011100041210006900152260001200221300001400233490000700247100002700254700001900281700002000300700001900320700002800339700002000367700001700387700002300404700001800427700002400445856007700469 2011 eng d00aWhen a habitat freezes solid: microorganisms over-winter within the ice column of a coastal Antarctic lake0 aWhen a habitat freezes solid microorganisms overwinter within th c06/2011 a401 - 4120 v761 aForeman, Christine, M.1 aDieser, Markus1 aGreenwood, Mark1 aCory, Rose, M.1 aLaybourn-Parry, Johanna1 aLisle, John, T.1 aJaros, Chris1 aMiller, Penney, L.1 aChin, Yu-Ping1 aMcKnight, Diane, M. uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2011.01061.x/full00655nas a2200193 4500008004100000245008400041210006900125260001100194300001400205490000600219100002700225700002500252700002500277700002500302700002100327700002700348700002300375856006300398 2010 eng d00aAbiotic nitrous oxide emission from the hypersaline Don Juan Pond in Antarctica0 aAbiotic nitrous oxide emission from the hypersaline Don Juan Pon c5/2010 a341 - 3440 v31 aSamarkin, Vladimir, A.1 aMadigan, Michael, T.1 aBowles, Marshall, W.1 aCasciotti, Karen, L.1 aPriscu, John, C.1 aMcKay, Christopher, P.1 aJoye, Samantha, B. uhttp://www.nature.com/ngeo/journal/v3/n5/full/ngeo847.html00722nas a2200193 4500008004100000020001800041245008800059210006900147260004200216300001400258100002500272700002400297700001700321700001700338700002100355700001700376700002400393856011100417 2010 eng d a978052188919300aAntarctic McMurdo Dry Valley stream ecosystems as analog to fluvial systems on Mars0 aAntarctic McMurdo Dry Valley stream ecosystems as analog to fluv aCambridgebCambridge University Press a139 - 1591 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aCarr, M., H.1 aBaeseman, J.1 aDoran, Peter, T.1 aLyons, Berry1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/antarctic-mcmurdo-dry-valley-stream-ecosystems-analog-fluvial-systems-mars00568nas a2200169 4500008004100000245009500041210006900136260001200205300001000217490000600227100001900233700002300252700002400275700002200299700002300321856005400344 2010 eng d00aEffect of instrument-specific response on the analysis of fulvic acid fluorescence spectra0 aEffect of instrumentspecific response on the analysis of fulvic  c07/2010 a67-780 v81 aCory, Rose, M.1 aMiller, Mathew, P.1 aMcKnight, Diane, M.1 aGuerard, Jennifer1 aMiller, Penney, L. uhttp://www.aslo.org/lomethods/free/2010/0067.html00474nas a2200109 4500008004100000245008300041210006900124260002700193100001400220700002400234856010600258 2010 eng d00aMicrobial interactions with dissolved organic matter in saline natural waters0 aMicrobial interactions with dissolved organic matter in saline n bUniversity of Colorado1 aCawley, K1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/microbial-interactions-dissolved-organic-matter-saline-natural-waters00662nas a2200181 4500008004100000245013300041210006900174260001200243300001400255490000800269100002400277700002200301700002000323700002100343700001800364700002700382856007100409 2010 eng d00aNew insights into the origin and evolution of Lake Vida, McMurdo Dry Valleys, Antarctica — A noble gas study in ice and brines0 aNew insights into the origin and evolution of Lake Vida McMurdo  c01/2010 a112 - 1220 v2891 aMalone, Jessica, L.1 aCastro, Clara, M.1 aHall, Chris, M.1 aDoran, Peter, T.1 aKenig, Fabien1 aMcKay, Christopher, P. uhttp://www.sciencedirect.com/science/article/pii/S0012821X0900633500918nas 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-sciences03833nas a2200217 4500008004100000245017200041210006900213260004600282300000800328490001000336520305700346653001503403653001903418653002103437653002503458653001903483653002303502100001603525700002403541856005003565 2009 eng d00aControls on stream and hyporheic temperatures, Taylor Valley, Antarctica and large-scale climate influences on interannual flow variation in the Onyx River, Antarctica0 aControls on stream and hyporheic temperatures Taylor Valley Anta aBoulder, CObUniversity of Coloradoc2009 a3170 vPh.D.3 a

The McMurdo Dry Valleys comprise the largest ice-free polar desert on the continent of Antarctica. My Ph.D. research investigated summertime glacial meltwater streams flowing through this region. This work is presented in Chapters 2 through 6 of my thesis. Chapters 2-5 present the work I have done related to hyporheic processes while Chapter 6 focuses on the hydroclimatological investigations I have carried out.

More specifically, Chapter 2 addresses the question: what are the dominant processes controlling dry valley stream temperatures? In particular, this investigation quantified the role of hyporheic exchange. The study found that in the Dry Valleys, exchange acted to decrease stream temperatures, accounting for 6–21% of cooling.

Chapter 3 discusses a follow up tracer study to investigate whether the comparatively large daily changes in dry valley stream temperatures (6-9°C) affect hyporheic processes, for instance through viscosity effects. Results showed that the hyporheic zone volume and exchange coefficient were lower during the warmer, afternoon stream/streambed temperature regime than during the cooler, morning one. A temperature-induced feedback mechanism that increases subsurface flow path preferentiality is proposed as a possible explanation for the reduction in hyporheic volume under warmer conditions. The tracer results also suggested a “Swiss Cheese” type conceptual model of the hyporheic zone in which flow takes place along paths weaving their way through isolated areas.

Chapter 4 presents work done to elucidate individual hyporheic flow path lengths and residence times. A streambed injection revealed some long (over 100 m) paths that were also fast, having subsurface travel times on par with the surface water. Hyporheic pipeflow is proposed as an explanation.

In Chapter 5 research is presented showing that nitrate and phosphate concentrations at specific locations in the hyporheic zone increase with the decreasing connectivity of that location to the stream.

Finally, Chapter 6 describes the large-scale climate conditions that prevailed during December and January during the highest and lowest flow summers of the Onyx River record, the longest flow record for Antarctica. Climate variables and regions in the Southern Hemisphere that had a statistically significant linear correlation to Onyx River flows were also identified. The highest flow summer on record, 2001-2, was found to have some unusual climate features when compared to the other high flow summers. It stands out as having an anomalous wind pattern that would have increased katabatic winds in the valleys, raising air temperatures and possibly depositing sediment on the glaciers, decreasing their albedo. It is also characterized by anomalously high incoming shortwave radiation. We postulate that those high levels may have been due in part to the unusually low concentrations of radiation absorbing stratospheric ozone prevalent over the valleys that particular summer.

10aAntarctica10aearth sciences10ahydroclimatology10ahyporheic flow paths10ahyporheic zone10astream temperature1 aCozzetto, K1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/30486636600675nas 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-rotifers01451nas 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.pdf00835nas 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-system00572nas a2200157 4500008004100000245006300041210006000104260003600164100002100200700001600221700001700237700001600254700002500270700002700295856009200322 2008 eng d00aAntarctic subglacial water: origin, evolution, and ecology0 aAntarctic subglacial water origin evolution and ecology aOxfordbOxford University Press1 aPriscu, John, C.1 aTulaczyk, S1 aStudinger, M1 aKenicutt, M1 aChristner, Brent, C.1 aForeman, Christine, M. uhttps://mcm.lternet.edu/content/antarctic-subglacial-water-origin-evolution-and-ecology00526nas a2200169 4500008004100000245004000041210004000081260003000121300001000151100002500161700001600186700002100202700002000223700002700243700001700270856006900287 2008 eng d00aBacteria in Subglacial Environments0 aBacteria in Subglacial Environments aNew YorkbSpringer Verlag a51-711 aChristner, Brent, C.1 aSkidmore, M1 aPriscu, John, C.1 aTranter, Martyn1 aForeman, Christine, M.1 aMargesin, R. uhttps://mcm.lternet.edu/content/bacteria-subglacial-environments00626nas 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-antarctica00685nas a2200205 4500008004100000245010300041210006900144260000900213490000700222100002300229700002300252700002900275700001500304700002300319700002100342700001500363700001500378700002500393856006100418 2008 eng d00aReply to comment by K. Gajewski on “Abrupt environmental change in Canada's northernmost lake”0 aReply to comment by K Gajewski on Abrupt environmental change in c20080 v351 aAntoniades, Dermot1 aCrawley, Catherine1 aDouglas, Marianne, S. V.1 aPienitz, R1 aAndersen, Dale, T.1 aDoran, Peter, T.1 aHawes, Ian1 aPollard, W1 aVincent, Warwick, F. uhttp://www.agu.org/pubs/crossref/2008/2007GL032889.shtml00949nas 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.pdf00499nas a2200121 4500008004100000245007700041210006900118260003100187490000900218100002400227700002300251856010300274 2007 eng d00aEcotoxicity and microbial biogeochemistry of Fluoride in Antarctic soils0 aEcotoxicity and microbial biogeochemistry of Fluoride in Antarct bDartmouth Collegec07/20070 vB.S.1 aCollins, Pamela, M.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/ecotoxicity-and-microbial-biogeochemistry-fluoride-antarctic-soils00763nas 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-stability00704nas a2200169 4500008004100000245010300041210006900144260005400213100002500267700002400292700002100316700001700337700001700354700001900371700002700390856011700417 2007 eng d00aTrends in discharge and flow season timing of the Onyx River, Wright Valley, Antarctica since 19690 aTrends in discharge and flow season timing of the Onyx River Wri bU.S. Geological Survey Open-File Report 2007-10471 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aDoran, Peter, T.1 aLyons, Berry1 aCooper, Alan1 aRaymond, Carol1 aTeam, ISAES, Editorial uhttps://mcm.lternet.edu/content/trends-discharge-and-flow-season-timing-onyx-river-wright-valley-antarctica-196901738nas a2200229 4500008004100000245008300041210006900124260001200193300001100205490000700216520101800223653001101241100002501252700001201277700002401289700001101313700001301324700002501337700002101362700001601383856010901399 2006 eng d00aAntarctic Climate Cooling and Response of Diatoms in Glacial Meltwater Streams0 aAntarctic Climate Cooling and Response of Diatoms in Glacial Mel c04/2006 aL074060 v333 a

To understand biotic responses to an Antarctic cooling trend, we analyzed diatom samples from glacial meltwater streams in the McMurdo Dry Valleys, the largest ice-free area in Antarctica. Diatoms are abundant in these streams, and 24 of 40 species have only been found in the Antarctic. The percentage of these Antarctic diatom species increased with decreasing annual stream flow and increasing harshness of the stream habitat. The species diversity of assemblages reached a maximum when the Antarctic species accounted for 40–60% of relative diatom abundance. Decreased solar radiation and air-temperatures reduce annual stream flow, raising the dominance of these Antarctic species to levels above 60%. Thus, cooling favors the Antarctic species, and lowers diatom species diversity in this region.

10aBiggie1 aEsposito, Rhea, M.M.1 aHorn, S1 aMcKnight, Diane, M.1 aCox, M1 aGrant, M1 aSpaulding, Sarah, A.1 aDoran, Peter, T.1 aCozzetto, K uhttps://mcm.lternet.edu/content/antarctic-climate-cooling-and-response-diatoms-glacial-meltwater-streams00563nas 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/S003807170600221500609nas a2200145 4500008004100000245012000041210006900161300001200230490000700242100001600249700002400265700002200289700002400311856012800335 2006 eng d00aExperimental investigations into processes controlling stream and hyporheic temperatures, Fryxell Basin, Antarctica0 aExperimental investigations into processes controlling stream an a130-1530 v291 aCozzetto, K1 aMcKnight, Diane, M.1 aNylen, Thomas, H.1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/experimental-investigations-processes-controlling-stream-and-hyporheic-temperatures-fryxell00592nas a2200145 4500008004100000245010200041210006900143490000700212100002700219700001600246700001700262700002300279700002100302856012300323 2006 eng d00aMeasuring ecosystem response in a rapidly changing environment: the Latitudinal Gradient Project0 aMeasuring ecosystem response in a rapidly changing environment t0 v101 aHoward-Williams, Clive1 aPeterson, D1 aLyons, Berry1 aCattaneo-Vietti, R1 aGordon, Shulamit uhttps://mcm.lternet.edu/content/measuring-ecosystem-response-rapidly-changing-environment-latitudinal-gradient-project00585nas a2200133 4500008004100000245012400041210006900165300001000234490000700244100002400251700002300275700002400298856012900322 2006 eng d00aSpatial and temporal active layer dynamics along three glacial meltwater streams in the McMurdo Dry Valleys, Antarctica0 aSpatial and temporal active layer dynamics along three glacial m a42-530 v381 aConovitz, Peter, A.1 aMacDonald, Lee, H.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/spatial-and-temporal-active-layer-dynamics-along-three-glacial-meltwater-streams-mcmurdo-dry00812nas 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-antarctica00884nas 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-al00549nas a2200157 4500008004100000245009600041210006900137300001200206490000800218100002500226700002200251700002700273700001400300700002100314856005600335 2005 eng d00aGlacial ice cores: a model system for developing extraterrestrial decontamination protocols0 aGlacial ice cores a model system for developing extraterrestrial a572-5840 v1741 aChristner, Brent, C.1 aMikucki, Jill, A.1 aForeman, Christine, M.1 aDenson, J1 aPriscu, John, C. u/reports/lakes/ChristnerEtAl2005Decontamination.pdf00711nas 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-event02329nas a2200181 4500008004100000245009400041210006900135260004900204300000800253490000900261520166100270100002201931700001701953700002001970700002001990700002702010856011002037 2005 eng d00aMathematical Modeling of a Hydrocarbon Spill on the Ice Cover of Lake Fryxell, Antarctica0 aMathematical Modeling of a Hydrocarbon Spill on the Ice Cover of aColumbusbThe Ohio State Universityc06/2005 a1140 vM.S.3 a

Numerous perennially ice-covered lakes exist in the McMurdo Dry Valleys region of Antarctica. Ice cover melting on these lakes and meltwater infiltration are important processes affecting the ecology of these lakes. The three lakes in Taylor Valley, Lakes Bonney, Fryxell and Hoare, have been investigated since 1993 as part of the McMurdo Dry Valleys Long Term Ecological Research (MCM LTER) site. A Bell 212 helicopter flying in support of the National Science Foundation's Antarctic Research Program crashed on the frozen surface of Lake Fryxell on January 17, 2003. This resulted in the release of approximately 731 Liters (193 gallons) of diesel fuel and amounts of engine oil and hydraulic fluid. Two physically based models are developed that simulate heat, meltwater flow and solute transport. The first is a transient, one-dimensional, thermodynamic model, which can predict the temperature distribution in the ice cover, melting rate at the surface and at the bottom of ice cover, and ice thickness. The second model simulates unsaturated flow and solute transport and is used to estimate water content distribution and solute transport through the ice cover. The validation of heat transport model was accomplished by comparing model results with the original measurements of ice temperature at various depth in Lake Fryxell. Because of lack of the field data, validation of the unsaturated flow and solute transport model couldn't been accomplished, instead of model validation, programming code has been verified by comparing results with results generated by the HYDRUS 1D software, developed by U.S. Salinity Laboratory, USDA.

1 aKarnovic, Marinko1 aLyons, Berry1 aCarey, Anne, E.1 aBair, Scott, E.1 avan der Veen, Cornelis uhttps://mcm.lternet.edu/content/mathematical-modeling-hydrocarbon-spill-ice-cover-lake-fryxell-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.pdf00875nas 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-systems00648nas 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-science00566nas a2200157 4500008004100000245007700041210006900118260001200187300001200199490000700211100002400218700002400242700002000266700001800286856010400304 2004 eng d00aCan warming induce advances of polar glaciers, Taylor Valley, Antarctica0 aCan warming induce advances of polar glaciers Taylor Valley Anta c12/2004 a556-5640 v501 aFountain, Andrew, G1 aNeumann, Thomas, A.1 aGlenn, Paul, L.1 aChinn, Trevor uhttps://mcm.lternet.edu/content/can-warming-induce-advances-polar-glaciers-taylor-valley-antarctica00636nas a2200169 4500008004100000245010400041210006900145300000900214490000700223100001400230700002400244700002700268700001900295700001500314700001300329856012400342 2004 eng d00aChanges in fulvic acid redox state through the oxycline of a permanently ice-covered Antarctic lake0 aChanges in fulvic acid redox state through the oxycline of a per a1-200 v661 aFulton, J1 aMcKnight, Diane, M.1 aForeman, Christine, M.1 aCory, Rose, M.1 aStedmon, C1 aBlunt, E uhttps://mcm.lternet.edu/content/changes-fulvic-acid-redox-state-through-oxycline-permanently-ice-covered-antarctic-lake00811nas 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-biodiversity00394nas a2200121 4500008004100000245002600041210002500067260003800092100002100130700002500151700001900176856007700195 2004 eng d00aEarth's Icy Biosphere0 aEarths Icy Biosphere bAmerican Society for Microbiology1 aPriscu, John, C.1 aChristner, Brent, C.1 aBull, Alan, T. uhttp://mcm.lternet.edu/reports/lakes/PriscuChristner2004IcyBiosphere.pdf00626nas 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-soil00662nas 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-ecosystem00890nas 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-response00772nas 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-antarctic03551nas a2200217 4500008004100000245009000041210006900131260001200200300001400212490000800226520282700234653001103061100002103072700002703093700001903120700002003139700002403159700002203183700001703205856011103222 2002 eng d00aValley floor climate observations from the McMurdo Dry Valleys, Antarctica, 1986-20000 aValley floor climate observations from the McMurdo Dry Valleys A c12/2002 a4772-47840 v1073 a

Climate observations from the McMurdo dry valleys, East Antarctica are presented from a network of seven valley floor automatic meteorological stations during the period 1986 to 2000. Mean annual temperatures ranged from −14.8°C to −30.0°C, depending on the site and period of measurement. Mean annual relative humidity is generally highest near the coast. Mean annual wind speed increases with proximity to the polar plateau. Site-to-site variation in mean annual solar flux and PAR is due to exposure of each station and changes over time are likely related to changes in cloudiness. During the nonsummer months, strong katabatic winds are frequent at some sites and infrequent at others, creating large variation in mean annual temperature owing to the warming effect of the winds. Katabatic wind exposure appears to be controlled to a large degree by the presence of colder air in the region that collects at low points and keeps the warm less dense katabatic flow from the ground. The strong influence of katabatic winds makes prediction of relative mean annual temperature based on geographical position (elevation and distance from the coast) alone, not possible. During the summer months, onshore winds dominate and warm as they progress through the valleys creating a strong linear relationship (r2 = 0.992) of increasing potential temperature with distance from the coast (0.09°C km−1). In contrast to mean annual temperature, summer temperature lends itself quite well to model predictions, and is used to construct a statistical model for predicting summer dry valley temperatures at unmonitored sites.

10aBiggie1 aDoran, Peter, T.1 aMcKay, Christopher, P.1 aClow, Gary, D.1 aDana, Gayle, L.1 aFountain, Andrew, G1 aNylen, Thomas, H.1 aLyons, Berry uhttps://mcm.lternet.edu/content/valley-floor-climate-observations-mcmurdo-dry-valleys-antarctica-1986-200000571nas a2200133 4500008004100000245012300041210006900164300000900233490000700242100001800249700002000267700002300287856012700310 2001 eng d00aDetermining habitat suitability for soil invertebrates in an extreme environment: The McMurdo Dry Valleys, Antarctica.0 aDetermining habitat suitability for soil invertebrates in an ext a9-170 v131 aCourtright, E1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/determining-habitat-suitability-soil-invertebrates-extreme-environment-mcmurdo-dry-valleys00756nas a2200193 4500008004100000245013700041210006900178490000600247100002600253700002100279700002900300700001700329700002300346700001300369700001600382700001500398700002000413856012900433 2001 eng d00aThe influence of soil biodiversity on hydrological pathways and the transfer of materials between terrestrial and aquatic ecosystems0 ainfluence of soil biodiversity on hydrological pathways and the 0 v41 aBardgett, Richard, D.1 aAnderson, J., M.1 aBehan-Pelletier, Valerie1 aBrussaard, L1 aColeman, David, C.1 aEttma, C1 aMoldenke, A1 aSchimel, J1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/influence-soil-biodiversity-hydrological-pathways-and-transfer-materials-between-terrestrial00492nas a2200121 4500008004100000245008000041210006900121260002700190490000900217100002100226700002400247856009900271 2001 eng d00aRegrowth of cyanobacterial mats in Greek Creek and the impact of ecotourism0 aRegrowth of cyanobacterial mats in Greek Creek and the impact of bUniversity of Colorado0 vM.S.1 aChatfield, Ethan1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/regrowth-cyanobacterial-mats-greek-creek-and-impact-ecotourism00477nas a2200169 4500008004100000245002200041210002200063260003000085300001000115100002000125700002000145700002400165700001900189700002200208700002300230856005400253 2001 eng d00aSoil Biodiversity0 aSoil Biodiversity aNew YorkbSpringer Verlag a47-821 aWall, Diana, H.1 aAdams, Gina, A.1 aParsons, Andrew, N.1 aChapin, F., S.1 aSala, Osvaldo, E.1 aHuber-Sannwald, E. uhttps://mcm.lternet.edu/content/soil-biodiversity00553nas a2200121 4500008004100000245010800041210006900149260002700218490000900245100002400254700002400278856012900302 2000 eng d00aActive layer dynamics and hyporheic zone storage in three streams in the McMurdo Dy Valleys, Antarctica0 aActive layer dynamics and hyporheic zone storage in three stream bUniversity of Colorado0 vM.S.1 aConovitz, Peter, A.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/active-layer-dynamics-and-hyporheic-zone-storage-three-streams-mcmurdo-dy-valleys-antarctica00870nas a2200325 4500008004100000245005200041210005200093300001400145490000800159100002200167700001400189700001500203700001300218700001400231700001800245700001200263700001300275700001400288700001500302700002000317700001900337700001500356700001400371700001800385700001300403700002100416700001600437700001500453856007600468 2000 eng d00aGlobal biodiversity scenarios for the year 21000 aGlobal biodiversity scenarios for the year 2100 a1770-17740 v2871 aSala, Osvaldo, E.1 aKinzig, A1 aLeemans, R1 aLodge, D1 aMooney, H1 aOesterheld, M1 aPoff, N1 aSykes, M1 aWalker, B1 aWalkder, M1 aWall, Diana, H.1 aChapin, F., S.1 aArmesto, J1 aBerlow, E1 aBloomfield, J1 aDirzo, R1 aHuber-Sanwald, E1 aHuenneke, L1 aJackson, R uhttps://mcm.lternet.edu/content/global-biodiversity-scenarios-year-210001013nas a2200313 4500008004100000245014800041210006900189300001400258490000700272100001500279700001400294700001700308700002200325700001300347700001400360700001400374700002200388700001400410700001600424700001400440700001500454700002300469700001500492700002200507700001600529700001700545700002000562856011700582 2000 eng d00aGlobal change effects on above and below ground biodiversity in terrestrial ecosystems: interactions and implications for ecosystem functioning0 aGlobal change effects on above and below ground biodiversity in  a1089-10990 v501 aWolters, V1 aWardle, D1 aBrussaard, L1 aDangerfield, Mark1 aBrown, V1 aGiller, K1 aHooper, D1 aSala, Osvaldo, E.1 aTiedje, J1 avan Veen, J1 aSilver, W1 aBignell, D1 aColeman, David, C.1 aLavelle, P1 avan der Putten, W1 aDeRuiter, P1 aRusek, Josef1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/global-change-effects-above-and-below-ground-biodiversity-terrestrial-ecosystems00932nas a2200289 4500008004100000245012200041210006900163300001400232490000700246100001400253700001500267700002200282700001600304700001700320700001400337700001400351700001500365700001500380700001300395700001700408700002200425700002000447700001400467700002300481700001400504856012400518 2000 eng d00aInteractions between above and belowground biodiversity in terrestrial ecosystems: patterns, mechanisms and feedbacks0 aInteractions between above and belowground biodiversity in terre a1049-10610 v501 aHooper, D1 aLavelle, P1 avan der Putten, W1 aDeRuiter, P1 aRusek, Josef1 aSilver, W1 aTiedje, J1 aWolters, V1 aBignell, D1 aBrown, V1 aBrussaard, L1 aDangerfield, Mark1 aWall, Diana, H.1 aWardle, D1 aColeman, David, C.1 aGiller, K uhttps://mcm.lternet.edu/content/interactions-between-above-and-belowground-biodiversity-terrestrial-ecosystems-patterns00624nas a2200169 4500008004100000245009900041210006900140300001200209490000800221100001800229700002000247700002300267700001200290700001400302700001400316856012400330 2000 eng d00aNuclear and mitochondrial DNA sequence diversity in the Antarctic nematode Scottnema lindsayae0 aNuclear and mitochondrial DNA sequence diversity in the Antarcti a143-1530 v3221 aCourtright, E1 aWall, Diana, H.1 aVirginia, Ross, A.1 aVida, J1 aFrisse, L1 aThomas, W uhttps://mcm.lternet.edu/content/nuclear-and-mitochondrial-dna-sequence-diversity-antarctic-nematode-scottnema-lindsayae00594nas a2200157 4500008004100000245009500041210006900136300001400205490000700219653001100226100002400237700002300261700002200284700002000306856011000326 2000 eng d00aThe Origin of Soil Organic Matter in Taylor Valley, Antarctica: A Legacy of Climate Change0 aOrigin of Soil Organic Matter in Taylor Valley Antarctica A Lega a2377-23910 v8110alegacy1 aBurkins, Melody, B.1 aVirginia, Ross, A.1 aChamberlain, Page1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/origin-soil-organic-matter-taylor-valley-antarctica-legacy-climate-change00602nas a2200157 4500008004100000245010300041210006900144300001200213490000800225100001700233700002400250700001500274700001500289700001500304856012500319 2000 eng d00aUV radiation and potential biological effects beneath the perennial ice cover of an antarctic lake0 aUV radiation and potential biological effects beneath the perenn a155-1650 v4271 aKepner, R.L.1 aWharton, Robert, A.1 aCollier, R1 aCockell, C1 aJeffrey, W uhttps://mcm.lternet.edu/content/uv-radiation-and-potential-biological-effects-beneath-perennial-ice-cover-antarctic-lake00570nas a2200133 4500008004100000245013100041210006900172300001200241490000700253100001700260700001600277700002400293856011900317 1999 eng d00aCiliated protozoa of two antarctic lakes: analysis by quantitative protargol staining and examination of artificial substrates0 aCiliated protozoa of two antarctic lakes analysis by quantitativ a285-2940 v211 aKepner, R.L.1 aCoats, D.W.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/ciliated-protozoa-two-antarctic-lakes-analysis-quantitative-protargol-staining-and00587nas a2200169 4500008004100000245006800041210006600109300001200175490000700187100002400194700002000218700002500238700001900263700002400282700002000306856009100326 1999 eng d00aDry Valley streams in Antarctica: ecosystems waiting for water0 aDry Valley streams in Antarctica ecosystems waiting for water a985-9950 v491 aMcKnight, Diane, M.1 aNiyogi, Dev, K.1 aAlger, Alexander, S.1 aBomblies, Arne1 aConovitz, Peter, A.1 aTate, Cathy, M. uhttps://mcm.lternet.edu/content/dry-valley-streams-antarctica-ecosystems-waiting-water00544nas a2200157 4500008004100000245006500041210006500106100001500171700001500186700001400201700002700215700002100242700001300263700001600276856009400292 1999 eng d00aLake ice microbial communities in alpine and Antarctic lakes0 aLake ice microbial communities in alpine and Antarctic lakes1 aPsenner, 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