@article {4938, title = {Brief communication: Significant biases in ERA5 output for the McMurdo Dry Valleys region, Antarctica}, journal = {The Cryosphere}, volume = {18}, year = {2024}, month = {03/2024}, pages = {1207 - 1213}, abstract = {

The ERA5 climate reanalysis dataset plays an important role in applications such as monitoring and modeling climate system changes in polar regions, so the calibration of the reanalysis to ground observations is of great relevance. Here, we compare the 2 m air temperature time series of the ERA5 reanalysis and the near-surface bias-corrected reanalysis to the near-ground air temperature measured at 17 automatic weather stations (AWSs) in the McMurdo Dry Valleys, Antarctica. We find that the reanalysis data have biases that change with the season of the year and do not clearly correlate with elevation. Our results show that future work should rely on secondary observations to calibrate when using the ERA5 reanalysis in polar regions.

}, keywords = {LTER-MCM}, doi = {10.5194/tc-18-1207-2024}, url = {https://tc.copernicus.org/articles/18/1207/2024}, author = {Garza-Gir{\'o}n, Ricardo and Tulaczyk, Slawek M.} } @article {4940, title = {McMurdo Dry Valley lake edge {\textquoteleft}moats{\textquoteright}: The ecological intersection between terrestrial and aquatic polar desert habitat}, journal = {Antarctic Science}, year = {2024}, month = {04/2024}, pages = {1 - 17}, abstract = {

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

}, keywords = {LTER-MCM, connectivity, ecosystem, ice, microbial mats, transition}, issn = {0954-1020}, doi = {10.1017/S0954102024000087}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/mcmurdo-dry-valley-lake-edge-moats-the-ecological-intersection-between-terrestrial-and-aquatic-polar-desert-habitats/31D94DD51E651603482A3AE6E8A52A57}, author = {Stone, Michael S. and Devlin, Shawn and Ian Hawes and Kathleen A. Welch and Michael N. Gooseff and Cristina D. Takacs-Vesbach and Rachael M. Morgan-Kiss and Byron Adams and John E. Barrett and John C. Priscu and Peter T. Doran} } @article {4844, title = {Causes and characteristics of electrical resistivity variability in shallow (<4 m) soils in Taylor Valley, East Antarctica}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {128}, year = {2023}, month = {02/2023}, pages = {e2022JF006696}, abstract = {

Airborne electromagnetic surveys collected in December 2011 and November 2018 and three soil sampling transects were used to analyze the spatial heterogeneity of shallow (\<4 m) soil properties in lower Taylor Valley (TV), East Antarctica. Soil resistivities from 2011 to 2018 ranged from \∼33 Ωm to \∼3,500 Ωm with 200 Ωm assigned as an upper boundary for brine-saturated sediments. Elevations below \∼50 m above sea level (masl) typically exhibit the lowest resistivities with resistivity increasing at high elevations on steeper slopes. Soil water content was empirically estimated from electrical resistivities using Archie\&$\#$39;s Law and range from \∼\<1\% to \∼68\% by volume. An increase in silt- and clay-sized particles at low elevations increases soil porosity but decreases hydraulic conductivity, promoting greater residence times of soil water at low elevations near Lake Fryxell. Soil resistivity variability between 2011 and 2018 shows soils at different stages of soil freeze-thaw cycles, which are caused predominantly by solar warming of soils as opposed to air temperature. This study furthers the understanding of the hydrogeologic structure of the shallow subsurface in TV and identifies locations of soils that are potentially prone to greater rates of thaw and resulting ecosystem homogenization of soil properties from projected increases in hydrological connectivity across the region over the coming decades.

}, keywords = {LTER-MCM, active layer, airborne electromagnetic surveys, McMurdo Dry Valleys, permafrost dynamics}, issn = {2169-9003}, doi = {10.1029/2022JF006696}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2022JF006696}, author = {Gutterman, William S. and Peter T. Doran and Ross A. Virginia and John E. Barrett and Myers, Krista F. and Tulaczyk, Slawek M. and Foley, Neil T. and Jill A. Mikucki and Hilary A. Dugan and Grombacher, Denys and Bording, Thue S. and Auken, E.} } @article {4944, title = {Change at 85 degrees south: Shackleton Glacier region proglacial lakes from 1960 to 2020}, journal = {Annals of Glaciology}, year = {2023}, month = {05/2023}, abstract = {

Over the last two decades, anomalous warming events have been observed in coastal Antarctic regions. While these events have been documented in the Ross Sea sector, the Antarctic interior is believed to have been buffered from warming. In this work, we present data from lakes located near Mt. Heekin and Thanksgiving Valley (~85\° S) along the Shackleton Glacier, which are believed to be the southern-most Antarctic dry valley lakes. In 2018, the lakes were characterized, repeat satellite images were examined, and lake water chemistry was measured. Our analysis shows that lake areas recently increased, and the water-soluble ion chemistry indicates a flushing of salts from periglacial soils, likely from increased glacial melt as illustrated by water isotope data. Our results show that high southern latitude ice-free areas have likely been affected by warm pulses over the past 60 years and these pulses may be quasi-synchronous throughout the Transantarctic Mountains.

}, keywords = {LTER-MCM, Antarctic glaciology, climate change, meltwater chemistry}, issn = {0260-3055}, doi = {10.1017/aog.2023.27}, url = {https://www.cambridge.org/core/journals/annals-of-glaciology/article/change-at-85-degrees-south-shackleton-glacier-region-proglacial-lakes-from-1960-to-2020/565D96AD7AE72BD22C49CCB772867AC4}, author = {Melisa A. Diaz and Christopher B. Gardner and Elliot, David H. and Byron Adams and W. Berry Lyons} } @article {4856, title = {Differentiating physical and biological storage of nitrogen along an intermittent Antarctic stream corridor}, journal = {Freshwater Science}, volume = {42}, year = {2023}, month = {09/2023}, abstract = {

In many temperate streams, biological uptake of N acts to attenuate the transport of excess N from allochthonous anthropogenic imports. Relatively few studies have determined how this N uptake relates to the magnitude of physical vs. biological N storage in the stream corridor, especially for intermittent systems where allochthonous N imports are often low and N transport may only occur during brief periods of streamflow. Glacial meltwater streams in the McMurdo Dry Valleys of Antarctica provide an excellent setting to quantify autochthonous N cycling and storage processes supported by abundant algal mats and well-connected hyporheic zones. We combined historic point-scale sediment and periphyton sample datasets with remote sensing-based modeling of periphyton coverage to estimate how much N was stored in periphyton biomass and the hyporheic zone of a 5-km long McMurdo Dry Valley stream corridor (\>100,000 m2). We contextualized these N storage calculations by estimating the magnitude of annual N imports to and exports from the stream corridor based on \>2 decades of streamflow and surface water data, source glacier ice cores and meltwater data, and past studies of local aeolian deposition and biological N fixation rates. We found that in this highly oligotrophic system, stream corridor-scale N storage was ~1000x that of total annual N import or export fluxes. More than 90\% of this temporarily stored N was autochthonous organic matter in the shallow (\<10 cm) hyporheic zone, which acts as a reservoir that sustains N availability in the water column. Despite its location in a polar desert devoid of higher-order vegetation, area-normalized N storage (~40 g N/m2) was greater than that reported for streams at lower latitudes (~1\–22 g N/m2). We also demonstrated that NH4+ sorption to stream sediment may be an important physicochemical N storage mechanism that responds to short-term fluctuations in streamflow and governs the mobility of inorganic N. Altogether, this research illustrates the importance of quantifying N storage within stream corridors when evaluating the significance of internal cycling and physical retention processes that modulate N availability.

}, keywords = {LTER-MCM, hyporheic zone, McMurdo LTER, nitrogen cycling, nutrient budget, organic matter, periphyton}, issn = {2161-9549}, doi = {10.1086/725676}, url = {https://www.journals.uchicago.edu/doi/10.1086/725676}, author = {Singley, Joel G. and Salvatore, Mark R. and Michael N. Gooseff and Diane M. McKnight and Eve-Lyn S. Hinckley} } @article {4942, title = {The distribution of surface soil moisture over space and time in eastern Taylor Valley, Antarctica}, journal = {Remote Sensing}, volume = {15}, year = {2023}, month = {06/2023}, pages = {3170}, abstract = {

Available soil moisture is thought to be the limiting factor for most ecosystem processes in the cold polar desert of the McMurdo Dry Valleys (MDVs) of Antarctica. Previous studies have shown that microfauna throughout the MDVs are capable of biological activity when sufficient soil moisture is available (~2\–10\% gravimetric water content), but few studies have attempted to quantify the distribution, abundance, and frequency of soil moisture on scales beyond that of traditional field work or local field investigations. In this study, we present our work to quantify the soil moisture content of soils throughout the Fryxell basin using multispectral satellite remote sensing techniques. Our efforts demonstrate that ecologically relevant abundances of liquid water are common across the landscape throughout the austral summer. On average, the Fryxell basin of Taylor Valley is modeled as containing 1.5 \± 0.5\% gravimetric water content (GWC) across its non-fluvial landscape with ~23\% of the landscape experiencing an average GWC \> 2\% throughout the study period, which is the observed limit of soil nematode activity. These results indicate that liquid water in the soils of the MDVs may be more abundant than previously thought, and that the distribution and availability of liquid water is dependent on both soil properties and the distribution of water sources. These results can also help to identify ecological hotspots in the harsh polar Antarctic environment and serve as a baseline for detecting future changes in the soil hydrological regime.

}, keywords = {LTER-MCM, Dry valleys, ecology, hydrology, remote sensing, soil moisture}, doi = {10.3390/rs15123170}, url = {https://www.mdpi.com/2072-4292/15/12/3170}, author = {Salvatore, Mark R. and Barrett, John E. and Fackrell, Laura E. and Sokol, Eric R. and Levy, Joseph S. and Kuentz, Lily C. and Gooseff, Michael N. and Adams, Byron J. and Power, Sarah N. and Knightly, J. Paul and Matul, Haley M. and Szutu, Brian and Doran, Peter T.} } @article {4865, title = {MacroSheds: A synthesis of long-term biogeochemical, hydroclimatic, and geospatial data from small watershed ecosystem studies}, journal = {Limnology and Oceanography Letters}, volume = {8}, year = {2023}, month = {06/2023}, pages = {419 - 452}, abstract = {

The US Federal Government supports hundreds of watershed monitoring efforts from which solute fluxes can be calculated. Although instrumentation and methods vary between studies, the data collected and their motivating questions are remarkably similar. Nevertheless, little effort toward their compilation has previously been made. The MacroSheds project has developed a future-friendly system for harmonizing daily time series of streamflow, precipitation, and solute chemistry from 169+ watersheds, and supplementing each with watershed attributes. Here, we describe the breadth of MacroSheds data, and detail the steps involved in rendering each data product. We provide recommendations for usage and discuss when other datasets might be more suitable. The MacroSheds dataset is an unprecedented resource for watershed science, and for hydrology, as a small-watershed supplement to existing collections of streamflow predictors, like CAMELS and GAGES-II. The MacroSheds platform includes a web dashboard for visualization and an R package for data access and analysis.

}, keywords = {LTER-MCM}, issn = {2378-2242}, doi = {10.1002/lol2.v8.310.1002/lol2.10325}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lol2.10325}, author = {Vlah, Michael J. and Rhea, Spencer and Bernhardt, Emily S. and Slaughter, Weston and Gubbins, Nick and DelVecchia, Amanda G. and Thellman, Audrey and Ross, Matthew R. V.} } @article {4841, title = {Postglacial adaptations enabled colonization and quasi-clonal dispersal of ammonia-oxidizing archaea in modern European large lakes}, journal = {Science Advances}, volume = {9}, year = {2023}, month = {02/2023}, pages = {eadc9392}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1126/sciadv.adc9392}, url = {https://www.science.org/doi/10.1126/sciadv.adc9392}, author = {Ngugi, David Kamanda and Salcher, Michaela M. and Andrei, Adrian-Stefan and Ghai, Rohit and Klotz, Franziska and Chiriac, Maria-Cecilia and Ionescu, Danny and B{\"u}sing, Petra and Grossart, Hans-Peter and Xing, Peng and John C. Priscu and Alymkulov, Salmor and Pester, Michael} } @article {4845, title = {Spatial patterns of major ions and their relationship to sediment concentration in near surface glacier ice, Taylor Valley Antarctica}, journal = {Journal of Geophysical Research: Earth Surface}, year = {2023}, month = {03/2024}, abstract = {

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

}, keywords = {LTER-MCM}, issn = {2169-9003}, doi = {10.1029/2022JF006980}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2022JF006980}, author = {Bergstrom, Anna J. and Kathleen A. Welch and Michael N. Gooseff} } @article {4714, title = {Barotropic seiches in a perennially ice-covered lake, East Antarctica}, journal = {Limnology and Oceanography Letters}, volume = {7}, year = {2022}, month = {02/2022}, pages = {26 - 33}, abstract = {

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

}, keywords = {LTER-MCM}, issn = {2378-2242}, doi = {10.1002/lol2.10226}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.10226}, author = {Castendyk, Devin and Hilary A. Dugan and Gallagher, Hugh A. and Pujara, Nimish and Peter T. Doran and John C. Priscu and W. Berry Lyons} } @article {4818, title = {Cross-site comparisons of dryland ecosystem response to climate change in the US Long-Term Ecological Research Network}, journal = {BioScience}, year = {2022}, month = {08/2022}, abstract = {

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.

}, keywords = {LTER-MCM, ANPP, climate change, Disturbance, drought, LTER, wildfire}, issn = {0006-3568}, doi = {10.1093/biosci/biab134}, url = {https://academic.oup.com/bioscience/advance-article/doi/10.1093/biosci/biab134/6654840}, author = {Hudson, Amy R. and Debra P. C. Peters and J.M. Blair and Childers, Daniel L. and Peter T. Doran and Geil, Kerrie and Michael N. Gooseff and Gross, Katherine L. and Haddad, Nick M. and Pastore, Melissa A. and Rudgers, Jennifer A. and Osvaldo E. Sala and Seabloom, Eric W. and Shaver, Gaius} } @article {4815, title = {Dissolved organic carbon chemostasis in Antarctic polar desert streams}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {127}, year = {2022}, month = {07/2022}, pages = {e2021JG006649}, abstract = {

Dissolved organic carbon (DOC) is a key variable impacting stream biogeochemical processes. The relationship between DOC concentration (C) and stream discharge (q) can elucidate spatial and temporal DOC source dynamics in watersheds. In the ephemeral glacial meltwater streams of the McMurdo Dry Valleys (MDV), Antarctica, the C-q relationship has been applied to dissolved inorganic nitrogen and weathering solutes including silica, which all exhibit chemostatic C-q behavior; but DOC-q dynamics have not been studied. DOC concentrations here are low compared to temperate streams, in the range of 0.1-2 mg C l-1, and their chemical signal clearly indicates derivation from microbial biomass (benthic mats and hyporheic biofilm). To investigate whether the DOC generation rate from these autochthonous organic matter pools was sufficient to maintain chemostasis for DOC, despite these streams\&$\#$39; large diel and interannual fluctuations in discharge, we fit the long-term DOC-q data to a power law and an advection-reaction model. Model outputs and coefficients of variation characterize the DOC-q relationship as chemostatic for several MDV streams. We propose a conceptual model in which hyporheic carbon storage, hyporheic exchange rates, and net DOC generation rates are key interacting components that enable chemostatic DOC-q behavior in MDV streams. This model clarifies the role of autochthonous carbon stores in maintaining DOC chemostasis and may be useful for examining these relationships in temperate systems, which typically have larger sources of bioavailable autochthonous organic carbon than MDV streams but where this autochthonous signal could be masked by a stronger allochthonous contribution.

}, keywords = {LTER-MCM, Antarctica, chemostasis, concentration-discharge, DOC, ephemeral streams, LTER}, doi = {10.1029/2021JG006649}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2021JG006649}, author = {Torrens, Christa L. and Michael N. Gooseff and Diane M. McKnight} } @article {4834, title = {Lipid biomarkers from microbial mats on the McMurdo Ice Shelf, Antarctica: Signatures for life in the cryosphere}, journal = {Frontiers in Microbiology}, volume = {13}, year = {2022}, month = {06/2022}, pages = {903621}, abstract = {

Persistent cold temperatures, a paucity of nutrients, freeze-thaw cycles, and the strongly seasonal light regime make Antarctica one of Earth\’s least hospitable surface environments for complex life. Cyanobacteria, however, are well-adapted to such conditions and are often the dominant primary producers in Antarctic inland water environments. In particular, the network of meltwater ponds on the \‘dirty ice\’ of the McMurdo Ice Shelf is an ecosystem with extensive cyanobacteria-dominated microbial mat accumulations. This study investigated intact polar lipids (IPLs), heterocyte glycolipids (HGs), and bacteriohopanepolyols (BHPs) in combination with 16S and 18S rRNA gene diversity in microbial mats of twelve ponds in this unique polar ecosystem. To constrain the effects of nutrient availability, temperature and freeze-thaw cycles on the lipid membrane composition, lipids were compared to stromatolite-forming cyanobacterial mats from ice-covered lakes in the McMurdo Dry Valleys as well as from (sub)tropical regions and hot springs. The 16S rRNA gene compositions of the McMurdo Ice Shelf mats confirm the dominance of Cyanobacteria and Proteobacteria while the 18S rRNA gene composition indicates the presence of Ochrophyta, Chlorophyta, Ciliophora, and other microfauna. IPL analyses revealed a predominantly bacterial community in the meltwater ponds, with archaeal lipids being barely detectable. IPLs are dominated by glycolipids and phospholipids, followed by aminolipids. The high abundance of sugar-bound lipids accords with a predominance of cyanobacterial primary producers. The phosphate-limited samples from the (sub)tropical, hot spring, and Lake Vanda sites revealed a higher abundance of aminolipids compared to those of the nitrogen-limited meltwater ponds, affirming the direct affects that N and P availability have on IPL compositions. The high abundance of polyunsaturated IPLs in the Antarctic microbial mats suggests that these lipids provide an important mechanism to maintain membrane fluidity in cold environments. High abundances of HG keto-ols and HG keto-diols, produced by heterocytous cyanobacteria, further support these findings and reveal a unique distribution compared to those from warmer climates.

}, keywords = {LTER-MCM, Antarctica, bacteriohopanepolyol, cyanobacteria, heterocyte glycolipids, homeoviscous adaptation, intact polar lipid, microbial mats}, doi = {10.3389/fmicb.2022.90362110.3389/fmicb.2022.903621.s001}, url = {https://www.frontiersin.org/articles/10.3389/fmicb.2022.903621/full}, author = {Evans, Thomas W. and Kalambokidis, Maria J. and Jungblut, Anne D. and Millar, Jasmin L. and Bauersachs, Thorsten and Grotheer, Hendrik and Mackey, Tyler J. and Ian Hawes and Summons, Roger E.} } @article {4777, title = {Long-term stream hydrology and meteorology of a polar desert, the McMurdo Dry Valleys, Antarctica}, journal = {Hydrological Processes}, volume = {36}, year = {2022}, month = {06/2022}, pages = {e14623}, abstract = {

The McMurdo Dry Valleys (MDVs; 77.50\°S, 162.25\°E) make up the largest ice-free region of Antarctica at 3500 km2. Their position near the coast of the Ross Sea provides for a milder climate than much of the rest of the continent. Alpine and piedmont glaciers in the MDVs melt during the austral summer providing water to down gradient streams and terminal lakes on valley floors. There are currently 14 meteorological stations and 17 stream gauges operating across the MDVs, some with continuous records that go back to 1969. This relatively high density of monitoring stations reflects the fact that glaciers of different sizes and elevation ranges are the main source of water to streams. Thus, each glacier represents a different watershed. The bulk of these records start in the late 1980s/early 1990s. These data collection activities directly support research endeavors of the McMurdo Dry Valleys Long Term Ecological Research project, as well as a host of other science groups working in the MDVs. As such, both real time data and archived data from these sites is available through the online database interface of the project (https://mcmlter.org).

}, keywords = {LTER-MCM, Antarctica, LTER, McMurdo Dry Valleys, meltwater streams, polar desert, research catchment}, issn = {0885-6087}, doi = {10.1002/hyp.14623}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.14623}, author = {Gooseff, Michael N. and McKnight, Diane M. and Doran, Peter T. and Fountain, Andrew} } @article {4776, title = {Organic matter distribution in the icy environments of Taylor Valley, Antarctica}, journal = {Science of The Total Environment}, volume = {841}, year = {2022}, month = {10/2022}, pages = {156639}, abstract = {

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

}, keywords = {LTER-MCM, Antarctica, bacteria, ice cores, katabatic wind, marine aerosol, organic matter}, issn = {00489697}, doi = {10.1016/j.scitotenv.2022.156639}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0048969722037366}, author = {Guo, Bixi and Li, Wei and Santib{\'a}{\~n}ez, Pamela and John C. Priscu and Liu, Yongqin and Liu, Keshao} } @article {4758, title = {Patterns of interdisciplinary collaboration resemble biogeochemical relationships in the McMurdo Dry Valleys, Antarctica: A historical social network analysis of science, 1907{\textendash}2016}, journal = {Polar Research}, volume = {41}, year = {2022}, month = {04/2022}, pages = {8037}, abstract = {

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.

}, keywords = {LTER-MCM, critical physical geography, environmental history, history of science, science and technology studies, scientometrics, visual network analysis}, doi = {10.33265/polar.v41.8037}, url = {https://polarresearch.net/index.php/polar/article/view/8037}, author = {Chignell, Stephen M. and Howkins, Adrian and Gullett, Poppie and Andrew G Fountain} } @article {4735, title = {Ten scientific messages on risks and opportunities for life in the Antarctic}, year = {2022}, month = {02/2022}, institution = {Antarctic Environments Portal}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://environments.aq/publications/ten-scientific-messages-on-risks-and-opportunities-for-life-in-the-antarctic/}, author = {Gutt, Julian and Isla, Enrique and Xavier, Jos{\'e} C. and Adams, Byron J. and Ahn, In-Young and Cheng, C.-H. Christina and Colesie, Claudia and Cummings, Vonda J. and Griffiths, Huw J. and Hogg, Ian D. and McIntyre, Trevor and Meiners, Klaus M. and Pearce, David A. and Lloyd S. Peck and Piepenburg, Dieter and Reisinger, Ryan R. and Saba, Grace and Schloss, Irene R. and Signori, Camila N. and Smith, Craig R. and Vacchi, Marino and Verde, Cinzia and Diana H. Wall} } @article {4838, title = {The time is right for an Antarctic biorepository network}, journal = {Proceedings of the National Academy of Sciences}, volume = {119}, year = {2022}, month = {12/2022}, abstract = {

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\&$\#$39;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.

}, keywords = {LTER-MCM}, issn = {0027-8424}, doi = {10.1073/pnas.2212800119}, url = {https://www.pnas.org/doi/10.1073/pnas.2212800119}, author = {O{\textquoteright}Brien, Kristin M. and Crockett, Elizabeth L. and Byron Adams and Amsler, Charles D. and Appiah-Madson, Hannah J. and Collins, Allen and Desvignes, Thomas and Detrich, H. William and Distel, Daniel L. and Eppley, Sarah M. and Frable, Benjamin W. and Franz, Nico M. and Grim, Jeffrey M. and Kocot, Kevin M. and Mahon, Andrew R. and Mayfield-Meyer, Teresa J. and Jill A. Mikucki and Moser, William E. and Schmull, Michaela and Seid, Charlotte A. and Smith, Craig R. and Todgham, Anne E. and Watkins-Colwell, Gregory J.} } @article {4578, title = {Antarctic ecosystems in transition {\textendash} life between stresses and opportunities}, journal = {Biological Reviews}, year = {2021}, month = {06/2021}, abstract = {

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.

}, keywords = {LTER-MCM, adaptation, benthic dynamism, biogeochemical cycles, climate change, invasion, new habitats, ocean acidification, Primary production, range shifts, sea ice}, doi = {10.1111/brv.12679}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12679}, author = {Gutt, Julian and Isla, Enrique and Xavier, Jos{\'e} C. and Adams, Byron J. and Ahn, In-Young and Cheng, C.-H. Christina and Colesie, Claudia and Cummings, Vonda J. and di Prisco, Guido and Griffiths, Huw J. and Ian Hawes and Hogg, Ian D. and McIntyre, Trevor and Meiners, Klaus M. and Pearce, David A. and Lloyd S. Peck and Piepenburg, Dieter and Reisinger, Ryan R. and Saba, Grace and Schloss, Irene R. and Signori, Camila N. and Smith, Craig R. and Vacchi, Marino and Verde, Cinzia and Diana H. Wall} } @article {4585, title = {Antarctic water tracks: Microbial community responses to variation in soil moisture, pH, and salinity}, journal = {Frontiers in Microbiology}, volume = {12}, year = {2021}, month = {01/2021}, abstract = {

Ice-free soils in the McMurdo Dry Valleys select for taxa able to cope with challenging environmental conditions, including extreme chemical water activity gradients, freeze-thaw cycling, desiccation, and solar radiation regimes. The low biotic complexity of Dry Valley soils makes them well suited to investigate environmental and spatial influences on bacterial community structure. Water tracks are annually wetted habitats in the cold-arid soils of Antarctica that form briefly each summer with moisture sourced from snow melt, ground ice thaw, and atmospheric deposition via deliquescence and vapor flow into brines. Compared to neighboring arid soils, water tracks are highly saline and relatively moist habitats. They represent a considerable area (\∼5\–10 km2) of the Dry Valley terrestrial ecosystem, an area that is expected to increase with ongoing climate change. The goal of this study was to determine how variation in the environmental conditions of water tracks influences the composition and diversity of microbial communities. We found significant differences in microbial community composition between on- and off-water track samples, and across two distinct locations. Of the tested environmental variables, soil salinity was the best predictor of community composition, with members of the Bacteroidetes phylum being relatively more abundant at higher salinities and the Actinobacteria phylum showing the opposite pattern. There was also a significant, inverse relationship between salinity and bacterial diversity. Our results suggest water track formation significantly alters dry soil microbial communities, likely influencing subsequent ecosystem functioning. We highlight how Dry Valley water tracks could be a useful model system for understanding the potential habitability of transiently wetted environments found on the surface of Mars.

}, keywords = {LTER-MCM, Antarctica, extremophiles, Mars analog, microbial ecology, water tracks}, doi = {10.3389/fmicb.2021.616730}, url = {https://www.frontiersin.org/articles/10.3389/fmicb.2021.616730}, author = {George, Scott F. and Noah Fierer and Joseph S. Levy and Byron Adams} } @mastersthesis {4642, title = {Causes and characteristics of electrical resistivity variability in shallow (<4 m) soils in Taylor Valley, East Antarctica}, volume = {M.S.}, year = {2021}, month = {07/2021}, school = {Louisiana State University}, type = {masters}, address = {Baton Rouge}, abstract = {

The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are characterized as a polar desert environment. Soils in the region are typically very dry (\<1\% soil water by weight) and remain frozen for most of the year. Increases in air temperature and incoming solar radiation during the austral summer generate meltwater from glaciers, ground ice, and snow patches supplying moisture to soils and altering the physical and chemical makeup of the subsurface. Previous studies have utilized airborne electromagnetic surveys (AEM) to analyze groundwater systems in the deep subsurface but have not yet examined soil moisture in the shallow (\<4 m) subsurface. Here, I used electrical resistivity data from two AEM surveys (2011 and 2018) and soil geochemical data from three transects to characterize the spatial heterogeneity of soil properties in the near-subsurface of lower Taylor Valley. Soil resistivities from 2011 and 2018 range from 33.2 Ωm to 3535 Ωm with low elevations of \<100 meters above sea level (masl) typically displaying the lowest resistivities and high elevations displaying greater resistivities. Liquid brine fractions were empirically estimated from electrical resistivity values using Archie\’s Law and range from 0.3\% to 68.2\% for soils with resistivities \<200 Ωm. Additionally, soil transect data show greater percentages of fine-grained sediments (\<63 \µm) exist at elevations \<100 masl where soil resistivities begin decreasing. Resistivity variability in the subsurface is ultimately controlled by the site history, local and regional climate, soil salinity, soil moisture, soil lithology.

}, keywords = {LTER-MCM}, url = {https://digitalcommons.lsu.edu/gradschool_theses/5411}, author = {Gutterman, William S.} } @inbook {4581, title = {Chemical weathering in the McMurdo Dry Valleys, Antarctica}, booktitle = {Hydrogeology, Chemical Weathering, and Soil Formation}, series = {Geophysical Monograph Series}, number = {257}, year = {2021}, pages = {205-216}, publisher = {John Wiley \& Sons, Inc.}, organization = {John Wiley \& Sons, Inc.}, chapter = {11}, address = {Hoboken, NJ}, abstract = {

While chemical weathering has not always been considered an active process in the McMurdo Dry Valleys (MDV), Antarctica, long-term geochemical and hydrological investigations have provided an overall better understanding of chemical weathering in this polar desert environment. Liquid water on the landscape is limited to stream channels as well as shallow subsurface melt features, as there is no overland flow. Stream total suspended sediment loads are low, with the sources of sediment from stream channels, aeolian input, and/or from the surfaces of glaciers. MDV soils contain high concentrations of soluble salts with little clay material, but since absent of water, these soils are a minimal location of chemical weathering. Hyporheic zones exchange water during streamflow, and these areas control the stream geochemistry over various temporal scales. Hyporheic zones promote rapid aluminosilicate weathering by moving dilute glacial meltwater into intimate contact with sediment surfaces. Rapid weathering of the aluminosilicates in the streambed and hyporheic zones is the most plausible explanation for chemostasis observed in these streams, indicating that little to no catchment processes are necessary to explain the observed chemostasis in the MDV. Shallow subsurface waters with distinct geochemical signatures have much higher dissolved Si concentrations than the stream waters and indicate that they are responsible for enhanced aluminosilicate weathering in this polar desert environment. The dissolution of CaCO3 is also a major process in the hyporheic zones as generally the streams are unsaturated with respect to calcite. Cation-exchange reactions are also important in the evolution from Na-Cl brines to Ca-Cl brines within the soil column, while authigenic CaCO3 can both dissolve and precipitate depending on the condition of the system. Recently, stream channel landscapes are changing due to the melting of buried ice, creating thermokarst and water track features, resulting in a sediment and solute influx to the stream.

}, keywords = {LTER-MCM, aluminosilicate weathering, CaCO3 dissolution/precipitation, chemical weathering, hyporheic zone, McMurdo Dry Valleys}, doi = {10.1002/9781119563952.ch11}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1002/9781119563952.ch11}, author = {W. Berry Lyons and Leslie, Deborah L. and Michael N. Gooseff}, editor = {Hunt, Allen and Egli, Markus and Faybishenko, Boris} } @article {4627, title = {Connectivity: Insights from the U.S. Long Term Ecological Research Network}, journal = {Ecosphere}, volume = {12}, year = {2021}, month = {05/2021}, pages = {e03432}, abstract = {

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.

}, keywords = {LTER-MCM, alpine tundra, Antarctic polar desert, arid grassland, arid shrubland, coastal, estuary, salt marsh, Special Feature: Forecasting Earth{\textquoteright}s Ecosystems with Long-Term Ecological Research, urban ecosystem}, issn = {2150-8925}, doi = {10.1002/ecs2.v12.510.1002/ecs2.3432}, url = {https://onlinelibrary.wiley.com/doi/10.1002/ecs2.3432}, author = {Iwaniec, David M. and Michael N. Gooseff and Suding, Katharine N. and Johnson, David Samuel and Reed, Daniel C. and Debra P. C. Peters and Byron Adams and John E. Barrett and Bestelmeyer, Brandon T. and Castorani, Max C. N. and Cook, Elizabeth M. and Davidson, Melissa J. and Groffman, Peter M. and Hanan, Niall P. and Huenneke, L and Johnson, Pieter T. J. and Diane M. McKnight and Miller, Robert J. and Okin, Gregory S. and Preston, Daniel L. and Rassweiler, Andrew and Ray, Chris and Osvaldo E. Sala and Schooley, Robert and Seastedt, Timothy and Spasojevic, Marko J. and Vivoni, Enrique R.} } @article {4717, title = {Counting carbon: Quantifying biomass in the McMurdo Dry Valleys through orbital and field observations}, journal = {International Journal of Remote Sensing}, volume = {42}, year = {2021}, month = {10/2021}, pages = {8597 - 8623}, abstract = {

We use correlative field studies and high-resolution multispectral remote sensing data from the WorldView-2 instrument to estimate the abundance of photosynthetically active biomass (photoautotrophs consisting primarily of microbial mats and mosses) in Canada Stream in Taylor Valley, McMurdo Dry Valleys (MDV), Antarctica. In situ field investigations were performed to (1) acquire ground validation targets for atmospherically correcting satellite imagery, (2) derive spectra of \“pure\” geologic and biological endmembers, (3) estimate photoautotroph cover from remote sensing data, and (4) convert these coverage estimates to biomass using data collected in the field. Our results suggest that, on the morning of 12 December 2018, the Canada Stream system contained more than 3,800 kg of photosynthetically active carbon. Extrapolating our unmixing results to the entirety of the Fryxell basin of Taylor Valley, Antarctica, we model the presence of more than 750,000 kg of photosynthetically active carbon across the landscape and carbon fixation rates roughly equivalent to five hectares of tropical rainforest. The ability to spatially and temporally quantify the amount of photosynthetically active biomass using remote sensing data in the MDV of Antarctica is a revolutionary development that will help elucidate the ecological drivers and environmental responses in this cold desert landscape.

}, keywords = {LTER-MCM}, doi = {10.1080/01431161.2021.1981559}, url = {https://www.tandfonline.com/doi/full/10.1080/01431161.2021.1981559}, author = {Salvatore, Mark R. and John E. Barrett and Borges, Schuyler R. and Power, Sarah N. and Lee F. Stanish and Eric R. Sokol and Michael N. Gooseff} } @article {4586, title = {Diatoms in hyporheic sediments trace organic matter retention and processing in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {126}, year = {2021}, month = {02/2021}, pages = {e2020JG006097}, abstract = {

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

}, keywords = {LTER-MCM, benthic processes, biogenic silica, biogeochemical cycles processes and modeling, carbon cycling, diatoms, groundwater/surface water interactions, hyporheic zone, McMurdo Dry Valleys, nitrogen cycling, particulate organic matter}, doi = {10.1029/2020JG006097}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG006097}, author = {Heindel, Ruth C and Darling, Joshua P. and Singley, Joel G. and Bergstrom, Anna J. and Diane M. McKnight and Lukkari, Braeden M. and Kathleen A. Welch and Michael N. Gooseff} } @article {4644, title = {From the Heroic Age to today: What diatoms from Shackleton{\textquoteright}s Nimrod expedition can tell us about the ecological trajectory of Antarctic ponds}, journal = {Limnology and Oceanography Letters}, year = {2021}, month = {07/2021}, abstract = {

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\&$\#$39;s Nimrod expedition at Cape Royds, Antarctica, to compare with the same waterbodies a century later. We find historical samples to be almost identical to modern counterparts, and provide no evidence of exotic introductions despite increasing human activity. However, a shift occurred in the pond nearest Shackleton\&$\#$39;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.

}, keywords = {LTER-MCM}, issn = {2378-2242}, doi = {10.1002/lol2.10200}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.10200}, author = {Tyler J. Kohler and Howkins, Adrian and Eric R. Sokol and Kopalov{\'a}, Kate{\v r}ina and Cox, Aneliya and Darling, Joshua P. and Michael N. Gooseff and Diane M. McKnight} } @article {4646, title = {Geochemical zones and environmental gradients for soils from the central Transantarctic Mountains, Antarctica}, journal = {Biogeosciences}, volume = {18}, year = {2021}, month = {03/2021}, pages = {1629 - 1644}, abstract = {

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

}, keywords = {LTER-MCM}, doi = {10.5194/bg-18-1629-2021}, url = {https://bg.copernicus.org/articles/18/1629/2021/}, author = {Melisa A. Diaz and Christopher B. Gardner and Welch, Susan A. and W. Andrew Jackson and Adams, Byron J. and Diana H. Wall and Hogg, Ian D. and Noah Fierer and W. Berry Lyons} } @mastersthesis {4588, title = {Hydrologic response to foehn winds in the McMurdo Dry Valleys, Southern Victoria Land, Antarctica}, volume = {M.S.}, year = {2021}, month = {2020}, school = {University of Colorado Boulder}, type = {masters}, address = {Boulder, CO}, abstract = {

In the McMurdo Dry Valleys (MDVs), foehn winds are a principal vector of landscape connectivity that facilitate movement of materials between glaciers, streams, soils, lakes and other parts of the ecosystem. While previous publications show that turbulent, warm and dry foehn winds indirectly relate to an increase in lake level rise via an increase in degree days above freezing (DDAF), the direct quantified impact of foehn winds to streamflow and lake level rise remains unclear. The MDVs are the largest ice-free region of Antarctica, which experience minimal precipitation. Valley bottoms contain permanently ice-covered closed basin lakes filled with meltwater from outlet glaciers via stream channels. In Taylor Valley, several meteorological stations and lake monitoring stations record average measurements of weather conditions and lake conditions on 15 to 20-minute intervals. In this thesis, the meteorological definition of foehn winds is refined and hydrologic response to foehn winds is evaluated. During the austral summer streamflow season (November - February), foehn winds are predicted to increase meltwater generation and closed-basin lake level rise. Past publications have shown that foehn wind events contribute to lake ice sublimation year-round, whereas melt does not typically occur in nonsummer months. Analysis of non-summer lake ice ablation utilizing recent lake stage and ablation data is also explored herein. Although a significant correlation was not found, summer foehn winds appear to promote above average daily lake level rise given sufficient air temperatures. Daily average lake level rise is greater for longer periods (i.e., 4-day average daily rise \> 3-day average daily rise, etc.) indicating that there is at least a 4-day post-foehn impact on lake level rise during the summer. Lake ice ablation in non-summer months is shown to have a significant relationship with increasing foehn wind occurrence and wind-run. Because foehn winds are expected to increase with global warming, these hydrologic relationships aid in predicting the future of the McMurdo Dry Valley ecosystem in a warming world.

}, keywords = {LTER-MCM, Antarctica, foehn, foehn winds, hydrologic, katabatic, McMurdo, wind}, url = {https://www.proquest.com/docview/2488126937}, author = {Beane, Samuel J. and Michael N. Gooseff} } @article {4643, title = {Long-term shifts in feedbacks among glacier surface change, melt generation, and runoff, McMurdo Dry Valleys, Antarctica}, journal = {Hydrological Processes}, year = {2021}, month = {07/2021}, abstract = {

Glaciers of the McMurdo Dry Valleys (MDVs) Antarctica are the main source of streamflow in this polar desert. Because summer air temperatures hover near 0\°C small changes in the energy balance strongly affect meltwater generation. Here we demonstrate that increased surface roughness, which alters the turbulent transfer of energy between the ice surface and atmosphere, yields a detectable increase in meltwater runoff. At low elevations on the glaciers, basin-like topography became significantly rougher over 13\ years between repeat lidar surveys, yielding greater melt. In contrast, the smoother ice at higher elevation exhibited no detectable change in roughness. We pose a conceptual model of the cycle of glacier surface change as a result of climate forcing whereby glacier surfaces transition from being dominated by sublimation to becoming increasingly melt-dominated, which is reversible under prolonged cool periods. This research advances our understanding of warm season effects on polar glaciers.

}, keywords = {LTER-MCM}, issn = {0885-6087}, doi = {10.1002/hyp.14292}, url = {https://onlinelibrary.wiley.com/doi/10.1002/hyp.14292}, author = {Bergstrom, Anna J. and Michael N. Gooseff and Andrew G Fountain and Hoffman, Matthew} } @article {4597, title = {Metabolic capacity of the Antarctic cyanobacterium Phormidium pseudopriestleyi that sustains oxygenic photosynthesis in the presence of hydrogen sulfide}, journal = {Genes}, volume = {12}, year = {2021}, month = {03/2021}, pages = {426}, abstract = {

Sulfide inhibits oxygenic photosynthesis by blocking electron transfer between H2O and the oxygen-evolving complex in the D1 protein of Photosystem II. The ability of cyanobacteria to counter this effect has implications for understanding the productivity of benthic microbial mats in sulfidic environments throughout Earth history. In Lake Fryxell, Antarctica, the benthic, filamentous cyanobacterium Phormidium pseudopriestleyi creates a 1\–2 mm thick layer of 50 \µmol L\−1 O2 in otherwise sulfidic water, demonstrating that it sustains oxygenic photosynthesis in the presence of sulfide. A metagenome-assembled genome of P. pseudopriestleyi indicates a genetic capacity for oxygenic photosynthesis, including multiple copies of psbA (encoding the D1 protein of Photosystem II), and anoxygenic photosynthesis with a copy of sqr (encoding the sulfide quinone reductase protein that oxidizes sulfide). The genomic content of P. pseudopriestleyi is consistent with sulfide tolerance mechanisms including increasing psbA expression or directly oxidizing sulfide with sulfide quinone reductase. However, the ability of the organism to reduce Photosystem I via sulfide quinone reductase while Photosystem II is sulfide-inhibited, thereby performing anoxygenic photosynthesis in the presence of sulfide, has yet to be demonstrated.\ 

}, keywords = {LTER-MCM}, doi = {10.3390/genes12030426}, url = {https://www.mdpi.com/2073-4425/12/3/426}, author = {Lumian, Jessica E. and Jungblut, Anne D. and Dillon, Megan L. and Hawes, Ian and Peter T. Doran and Mackey, Tyler J. and Dick, Gregory J. and Grettenberger, Christen L. and Sumner, Dawn Y.} } @article {4768, title = {Patterns and trends of organic matter processing and transport: Insights from the US Long-term Ecological Research Network}, journal = {Climate Change Ecology}, volume = {2}, year = {2021}, month = {12/2021}, pages = {100025}, abstract = {

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.

}, keywords = {LTER-MCM, coupled biogeochemical cycles, cross-site synthesis, organic matter composition, organic matter storage, stabilization, transport}, issn = {26669005}, doi = {10.1016/j.ecochg.2021.100025}, url = {https://www.sciencedirect.com/science/article/pii/S2666900521000253}, author = {Harms, Tamara K. and Groffman, Peter M. and Aluwihare, Lihini and Craft, Christopher and Wieder, William R and Hobbie, S and Baer, Sara G. and J.M. Blair and Frey, Serita D. and Remucal, Christina K. and Rudgers, Jennifer A. and Collins, SL and Kominoski, John S. and Ball, Becky and John C. Priscu and John E. Barrett} } @article {4626, title = {The role of hyporheic connectivity in determining nitrogen availability: Insights from an intermittent Antarctic stream}, journal = {Journal of Geophysical Research: Biogeosciences}, year = {2021}, month = {04/2022}, abstract = {

Due to widespread manipulation of nitrogen (N), much research has focused on processes controlling the fate of anthropogenic N in streams. Yet, in a variety of oligotrophic systems, N fixed by periphyton is a significant driver of ecosystem metabolism. Due to difficulties partitioning allochthonous and autochthonous sources, there is limited information regarding how the latter is processed. Autochthonous N may be particularly important in alpine, arid, or polar environments. We test the hypothesis that the availability of remineralized autochthonous N is controlled by connectivity between the hyporheic zone and main channel due to the contrasting biogeochemical functions of benthic autotrophs (including N-fixing Nostoc) and hyporheic heterotrophs in an intermittent Antarctic stream. There, we collected surface water and hyporheic water concurrently at 4-6 hour intervals over a 32.5-hr period during one flow season and opportunistically throughout a second. Hyporheic water had 7 to 30 times greater nitrate-N concentrations relative to surface water across all flow conditions. In contrast, ammonium concentrations were generally lower, although similar among locations. Additionally, nitrate in hyporheic water was positively correlated with silica, an indicator of hyporheic residence time. A laboratory assay confirmed prior inferences that hyporheic microbial communities possess the functional potential to perform nitrification. Together, these findings suggest that remineralized autochthonous N accumulates in the hyporheic zone even as streamflow varies and likely subsidizes stream N availability\—which supports prior inferences from N stable isotope data at this site. These results highlight the importance of hyporheic connectivity in controlling autochthonous N cycling and availability in streams.

}, keywords = {LTER-MCM, Antarctica, autochthonous nitrogen, hyporheic zone, nitrogen cycling, streamflow}, issn = {2169-8953}, doi = {10.1029/2021JG006309}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JG006309}, author = {Singley, Joel G. and Gooseff, Michael N. and Diane M. McKnight and Eve-Lyn S. Hinckley} } @phdthesis {4692, title = {Stream corridor connectivity controls on nitrogen cycling}, volume = {PhD}, year = {2021}, month = {05/2021}, school = {University of Colorado Boulder}, type = {Doctoral}, address = {Boulder, CO, USA}, abstract = {

As water flows downstream, it is transported to and from environments that surround the visible stream. Along with surface water, these laterally and vertically connected environments comprise the stream corridor. Stream corridor connectivity influences many ecosystem services, including retention of excess nutrients. The subsurface area where stream water and groundwater mixes\—the hyporheic zone\—represents one of the most biogeochemically active parts of stream corridors.

The goal of my research is to advance understanding of how connectivity between different parts of a stream corridor controls the availability and retention of nitrogen (N), a nutrient that can limit primary productivity (low-N) and negatively impact water quality (excess N). First, I developed and applied a new machine learning method to objectively characterize the extent and variability of hyporheic exchange in terms of statistically unique functional zones using geophysical data. In applying this method to a benchmark dataset, I found that hyporheic extent does not scale uniformly with streamflow and that changes in the heterogeneity of connectivity differ over small (\<10 m) distances. Next, I leveraged the relative simplicity of ephemeral streams of the McMurdo Dry Valleys (MDVs), Antarctica, to isolate stream corridor processes that influence the fate of N. Through intensive field sampling campaigns, I found that the hyporheic zone can be a persistent source of N even in this low nutrient environment. Next, I combined historic sample data and remote sensing analysis to estimate how much N is stored in an MDV stream corridor. My results indicate that up to 103 times more N is stored in this system than is exported each year, with most of this storage in the shallow (\< 10 cm) hyporheic zone. Lastly, I examined 25 years of data for 10 streams to assess how stream corridor processes control concentration-discharge relationships. I found that in the absence of hillslope connectivity, stream corridor processes alone can maintain chemostasis \– relatively small concentration changes with large fluctuations in streamflow \– of both geogenic solutes and primary nutrients. My analysis also revealed that solutes subject to greater control by biological processes exhibit more variability within chemostatic relationships than weathering solutes that are only minimally influenced by biota.

Altogether, this research advances understanding of processes that are difficult to measure or are often overlooked in typical studies of temperate stream corridors. My findings provide insight into the surprising ways in which N is mobilized, transformed, and retained due to stream corridor connectivity in intermittent stream systems with few N inputs.

}, keywords = {LTER-MCM, Antarctica, hyporheic zone, nitrogen cycling, streams}, url = {https://www.proquest.com/docview/2572593127}, author = {Singley, Joel G.}, editor = {Eve-Lyn S. Hinckley and Michael N. Gooseff} } @article {4647, title = {Thermal legacy of a large paleolake in Taylor Valley, East Antarctica, as evidenced by an airborne electromagnetic survey}, journal = {The Cryosphere}, volume = {15}, year = {2021}, month = {08/2021}, pages = {3577 - 3593}, abstract = {

Previous studies of the lakes of the McMurdo Dry Valleys have attempted to constrain lake level history, and results suggest the lakes have undergone hundreds of meters of lake level change within the last 20 000 years. Past studies have utilized the interpretation of geologic deposits, lake chemistry, and ice sheet history to deduce lake level history; however a substantial amount of disagreement remains between the findings, indicating a need for further investigation using new techniques. This study utilizes a regional airborne resistivity survey to provide novel insight into the paleohydrology of the region. Mean resistivity maps revealed an extensive brine beneath the Lake Fryxell basin, which is interpreted as a legacy groundwater signal from higher lake levels in the past. Resistivity data suggest that active permafrost formation has been ongoing since the onset of lake drainage and that as recently as 1500\–4000 years BP, lake levels were over 60 m higher than present. This coincides with a warmer-than-modern paleoclimate throughout the Holocene inferred by the nearby Taylor Dome ice core record. Our results indicate Mid to Late Holocene lake level high stands, which runs counter to previous research finding a colder and drier era with little hydrologic activity throughout the last 5000 years.

}, keywords = {LTER-MCM}, doi = {10.5194/tc-15-3577-2021}, url = {https://tc.copernicus.org/articles/15/3577/2021/}, author = {Myers, Krista F. and Peter T. Doran and Tulaczyk, Slawek M. and Foley, Neil T. and Bording, Thue S. and Auken, Esben and Hilary A. Dugan and Jill A. Mikucki and Foged, Nikolaj and Grombacher, Denys and Ross A. Virginia} } @proceedings {4575, title = {Change in Pictures: Creating best practices in archiving ecological imagery for reuse}, journal = {Biodiversity Information Science and Standards}, volume = {4}, year = {2020}, month = {09/2020}, abstract = {

The research data repository of the Environmental Data Initiative (EDI) is building on over 30 years of data curation research and experience in the National Science Foundation-funded US Long-Term Ecological Research (LTER) Network. It provides mature functionalities, well established workflows, and now publishes all \‘long-tail\’ environmental data. High quality scientific metadata are enforced through automatic checks against community developed rules and the Ecological Metadata Language (EML) standard. Although the EDI repository is far along in making its data findable, accessible, interoperable, and reusable (FAIR), representatives from EDI and the LTER are developing best practices for the edge cases in environmental data publishing. One of these is the vast amount of imagery taken in the context of ecological research, ranging from wildlife camera traps to plankton imaging systems to aerial photography. Many images are used in biodiversity research for community analyses (e.g., individual counts, species cover, biovolume, productivity), while others are taken to study animal behavior and landscape-level change.

Some examples from the LTER Network include: using photos of a heron colony to measure provisioning rates for chicks (Clarkson and Erwin 2018) or identifying changes in plant cover and functional type through time (Peters et al. 2020). Multi-spectral images are employed to identify prairie species. Underwater photo quads are used to monitor changes in benthic biodiversity (Edmunds 2015). Sosik et al. (2020) used a continuous Imaging FlowCytobot to identify and measure phyto- and microzooplankton. Cameras at McMurdo Dry Valleys assess snow and ice cover on Antarctic lakes allowing estimation of primary production (Myers 2019).

It has been standard practice to publish numerical data extracted from images in EDI; however, the supporting imagery generally has not been made publicly available. Our goal in developing best practices for documenting and archiving these images is for them to be discovered and re-used. Our examples demonstrate several issues. The research questions, and hence, the image subjects are variable. Images frequently come in logical sets of time series. The size of such sets can be large and only some images may be contributed to a dedicated specialized repository. Finally, these images are taken in a larger monitoring context where many other environmental data are collected at the same time and location.

Currently, a typical approach to publishing image data in EDI are packages containing compressed (ZIP or tar) files with the images, a directory manifest with additional image-specific metadata, and a package-level EML metadata file. Images in the compressed archive may be organized within directories with filenames corresponding to treatments, locations, time periods, individuals, or other grouping attributes. Additionally, the directory manifest table has columns for each attribute. Package-level metadata include standard coverage elements (e.g., date, time, location) and sampling methods. This approach of archiving logical \‘sets\’ of images reduces the effort of providing metadata for each image when most information would be repeated, but at the expense of not making every image individually searchable. The latter may be overcome if the provided manifest contains standard metadata that would allow searching and automatic integration with other images.

}, keywords = {LTER-MCM, data repository, ecological data, metadata}, doi = {10.3897/biss.4.59082}, url = {https://biss.pensoft.net/article/59082/}, author = {Gries, Corinna and Beaulieu, Stace and Brown, Ren{\'e}e F. and Gastil-Buhl, Gastil and Elmendorf, Sarah C. and Hsieh, Hsun-Yi and Kui, Li and Maurer, Greg and Porter, John H.} } @article {4438, title = {A digital archive of human activity in the McMurdo Dry Valleys, Antarctica}, journal = {Earth System Science Data}, volume = {12}, year = {2020}, month = {05/2020}, abstract = {

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).

}, keywords = {LTER-MCM}, doi = {10.5194/essd-12-1117-2020}, url = {https://www.earth-syst-sci-data.net/12/1117/2020/}, author = {Howkins, Adrian and Chignell, Stephen M. and Gullett, Poppie and Andrew G Fountain and Brett, Melissa and Preciado, Evelin} } @phdthesis {4629, title = {The effect of sediment on hydrological and biogeochemical connectivity of glaciers within the McMurdo Dry Valley ecosystem, Antarctica}, volume = {Ph.D.}, year = {2020}, month = {2020}, school = {University of Colorado Boulder}, type = {doctoral}, address = {Boulder, CO}, abstract = {

Glaciers are an integral part of polar and alpine landscapes, providing water, inorganic, and organic material subsidies to downstream ecosystems. These subsides regulate downstream temperature, streamflow, and sediment supplies. Warming in high altitude and high latitude environments due to climate change is resulting in rapid and substantial mass loss of glaciers. In order to better predict impacts and future change to glaciers and downstream environments, we endeavor to better understand glacier physical and biogeochemical processes. Glaciers in the McMurdo Dry Valleys (MDVs) of Antarctica are very sensitive to slight changes in the energy balance. Small temperature or solar radiation increases can result in outsize increases in glacier melt, which is the main source of water for the MDV ecosystem. Sediment on the glacier surface is thought to be a key factor driving both melt and biogeochemical cycling on glaciers. This dissertation examines the distribution of sediment on the MDVs glacier surfaces, how it may have driven recent glacier morphological change, and identifies sediment-driven biogeochemical processes on the MDV glaciers. To do so, we carried out field data collection, field- and lab-based nutrient uptake experiments, geospatial analysis, and coupled sediment and energy balance modeling. We find that the glacier surfaces have changed in response to recent warm events by increasing roughness and the density of meltwater channels on the glacier surface. The increase in roughness occurred in already rough areas that serve as collection points for wind- and water-transported sediment. The rough surfaces and sediment have low albedo and can absorb a higher amount of energy, spurring additional melt. The distribution of sediment on the surface and in the top meter of ice is a reflection of patterns of wind deposition and seasonal melt on the glacier. The total amount of sediment in the top meter of ice agrees with previously measured rates of sediment deposition and follows a valley-wide pattern. The depth of the peak sediment concentration in the top meter of ice is a function of the thermal history of the glacier\– both summer energy balance and winter sublimation rates. We also find that the biota living in the sediment is capable of removing nutrients from glacier melt water, modulating the amount and form of nutrients delivered to downstream ecosystems. This research clarifies the role of glaciers within the larger MDV ecosystem. It also advances our understanding of surficial glacier melt and biogeochemistry, which can improve predictions of how the functional role of glaciers within their larger ecosystems will evolve due to climate change.

}, keywords = {LTER-MCM, glaciers, LTER, McMurdo Dry Valleys, meltwater, sediment}, url = {https://www.proquest.com/docview/2408273839}, author = {Bergstrom, Anna J. and Michael N. Gooseff} } @article {4488, title = {Genetic diversity of soil invertebrates corroborates timing estimates for past collapses of the West Antarctic Ice Sheet}, journal = {Proceedings of the National Academy of Sciences}, year = {2020}, month = {08/2020}, abstract = {

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.

}, keywords = {LTER-MCM, climate change, microarthropods, molecular clock, phylogeography, terrestrial biodiversity}, doi = {10.1073/pnas.2007925117}, url = {https://www.pnas.org/content/early/2020/08/19/2007925117}, author = {Gemma E. Collins and Hogg, Ian D. and Convey, Peter and Sancho, Leopoldo G. and Cowan, Don A. and W. Berry Lyons and Byron Adams and Diana H. Wall and Allan Green, T. G.} } @article {4420, title = {A global database of soil nematode abundance and functional group composition}, journal = {Scientific Data}, volume = {7}, year = {2020}, month = {03/2020}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s41597-020-0437-3}, url = {https://www.nature.com/articles/s41597-020-0437-3}, author = {van den Hoogen, Johan and Geisen, Stefan and Diana H. Wall and Wardle, D and Traunspurger, Walter and de Goede, Ron G. M. and Byron Adams and Ahmad, Wasim and Ferris, Howard and Richard D. Bardgett and Bonkowski, Michael and Campos-Herrera, Raquel and Cares, Juvenil E. and Caruso, Tancredi and de Brito Caixeta, Larissa and Chen, Xiaoyun and Costa, Sofia R. and Creamer, Rachel and da Cunha e Castro, Jos{\'e} and Dam, Marie and Djigal, Djibril and Escuer, Miguel and Griffiths, Bryan S. and Guti{\'e}rrez, Carmen and Hohberg, Karin and Kalinkina, Daria and Kardol, Paul and Kergunteuil, Alan and Korthals, Gerard and Krashevska, Valentyna and Kudrin, Alexey A. and Li, Qi and Liang, Wenju and Magilton, Matthew and Marais, Mariette and Mart{\'\i}n, Jos{\'e} Antonio Rodr{\'\i}guez and Matveeva, Elizaveta and Mayad, El Hassan and Mzough, E. and Mulder, Christian and Mullin, Peter and Neilson, Roy and Nguyen, T. A. Duong and Uffe N. Nielsen and Okada, Hiroaki and Rius, Juan Emilio Palomares and Pan, Kaiwen and Peneva, Vlada and Pellissier, Lo{\"\i}c and Carlos Pereira da Silva, Julio and Pitteloud, Camille and Powers, Thomas O. and Powers, Kirsten and Quist, Casper W. and Rasmann, Sergio and Moreno, Sara S{\'a}nchez and Scheu, Stefan and Set{\"a}l{\"a}, Heikki and Sushchuk, Anna and Tiunov, Alexei V. and Trap, Jean and Vesterg{\r a}rd, Mette and Villenave, Cecile and Waeyenberge, Lieven and Wilschut, Rutger and Wright, Daniel G. and Keith, Aidan M. and Yang, Jiue-in and Schmidt, Olaf and Bouharroud, R. and Ferji, Z. and van der Putten, Wim H. and Routh, Devin and Crowther, Thomas Ward} } @article {4489, title = {Nutrient uptake in the supraglacial stream network of an Antarctic glacier}, journal = {Journal of Geophysical Research: Biogeosciences}, year = {2020}, month = {08/2020}, abstract = {

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.

}, keywords = {LTER-MCM, McMurdo Dry Valleys, nitrogen, nutrient tracers, nutrient uptake, sediments, supraglacial streams}, doi = {10.1029/2020JG005679}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG005679}, author = {Bergstrom, Anna J. and Michael N. Gooseff and Singley, Joel G. and Cohen, Matthew J. and Kathleen A. Welch} } @article {4413, title = {The seasonal evolution of albedo across glaciers and the surrounding landscape of Taylor Valley, Antarctica}, journal = {The Cryosphere}, volume = {14}, year = {2020}, month = {03/2020}, pages = {769-788}, abstract = {

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\ oC, 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.

}, keywords = {LTER-MCM}, doi = {10.5194/tc-14-769-2020}, url = {https://www.the-cryosphere.net/14/769/2020/}, author = {Bergstrom, Anna J. and Michael N. Gooseff and Myers, Madeline and Peter T. Doran and Cross, Julian M.} } @article {4490, title = {Shotgun metagenomics reveal a diverse assemblage of protists in a model Antarctic soil ecosystem}, journal = {Environmental Microbiology}, year = {2020}, month = {08/2020}, abstract = {

The soils of the McMurdo Dry Valleys (MDV) of Antarctica are established models for understanding fundamental processes in soil ecosystem functioning (e.g. ecological tipping points, community structuring, and nutrient cycling) because the extreme physical environment drastically reduces biodiversity and ecological complexity. Understanding the functioning of MDV soils requires in-depth knowledge of the diversity of MDV soil species. Protists, which contribute significantly to soil ecosystem functioning worldwide, remain poorly characterized in the MDV. To better assess the diversity of MDV protists, we performed shotgun metagenomics on 18 sites representing a variety of landscape features and edaphic variables. Our results show MDV soil protists are diverse at both the genus (155 of 281 eukaryote genera) and family (120) levels, but comprise only 6\% of eukaryotic reads. Protists are structured by moisture, total N, and distance from the local coast, and possess limited richness in arid (\<5\% moisture) and at high elevation sites, known drivers of communities in the MDV. High relative diversity and broad distribution of protists in our study promotes these organisms as key members of MDV soil microbiomes and the MDV as a useful system for understanding the contribution of soil protists to the structure of soil microbiomes.

}, keywords = {LTER-MCM, Antarctica, extremophiles, functional groups, metagenomics, protozoa, soil microbiology}, doi = {10.1111/1462-2920.15198}, url = {https://sfamjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1462-2920.15198}, author = {Thompson, Andrew R. and Geisen, Stefan and Byron Adams} } @article {4463, title = {Silicon isotopes reveal a non-glacial source of silicon to Crescent Stream, McMurdo Dry Valleys, Antarctica}, journal = {Frontiers in Earth Science}, volume = {8}, year = {2020}, month = {06/2020}, abstract = {

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

}, keywords = {LTER-MCM}, doi = {10.3389/feart.2020.00229}, url = {https://www.frontiersin.org/articles/10.3389/feart.2020.00229/full}, author = {Hirst, Catherine and Opfergelt, Sophie and Fran{\c c}ois Gaspard and Hendry, Katharine R. and Hatton, Jade E. and Sue Welch and Diane M. McKnight and W. Berry Lyons} } @article {4153, title = {Biotic interactions are an unexpected yet critical control on the complexity of an abiotically driven polar ecosystem}, journal = {Communications Biology}, volume = {2}, year = {2019}, month = {02/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s42003-018-0274-5}, url = {https://www.nature.com/articles/s42003-018-0274-5}, author = {Charles K. Lee and Laughlin, Daniel C. and Bottos, Eric M. and Caruso, Tancredi and Joy, Kurt and John E. Barrett and Brabyn, Lars and Uffe N. Nielsen and Byron Adams and Diana H. Wall and D. W. Hopkins and Pointing, Steve B. and McDonald, Ian R. and Cowan, Don A. and Banks, Jonathan C. and Stichbury, Glen A. and Jones, Irfon and Zawar-Reza, Peyman and Katurji, Marwan and Hogg, Ian D. and Sparrow, Ashley D. and Storey, Bryan C. and Allan Green, T. G. and Craig S Cary} } @article {4294, title = {Environmental controls on bacteriohopanepolyol profiles of benthic microbial mats from Lake Fryxell, Antarctica}, journal = {Geobiology}, year = {2019}, month = {07/2019}, abstract = {

Bacteriohopanepolyols (BHPs) are pentacyclic triterpenoid lipids that contribute to the structural integrity and physiology of some bacteria. Because some BHPs originate from specific classes of bacteria, BHPs have potential as taxonomically and environmentally diagnostic biomarkers. For example, a stereoisomer of bacteriohopanetetrol (informally BHT II) has been associated with anaerobic ammonium oxidation (anammox) bacteria and suboxic to anoxic marine environments where anammox is active. As a result, the detection of BHT II in the sedimentary record and fluctuations in the relative abundance of BHT II may inform reconstructions of nitrogen cycling and ocean redox changes through the geological record. However, there are uncertainties concerning the sources of BHT II and whether or not BHT II is produced in abundance in non-marine environments, both of which are pertinent to interpretations of BHT II signatures in sediments. To address these questions, we investigate the BHP composition of benthic microbial mats from Lake Fryxell, Antarctica. Lake Fryxell is a perennially ice-covered lake with a sharp oxycline in a density-stabilized water column. We describe the diversity and abundance of BHPs in benthic microbial mats across a transect from oxic to anoxic conditions. Generally, BHP abundances and diversity vary with the morphologies of microbial mats, which were previously shown to reflect local environmental conditions, such as irradiance and oxygen and sulfide concentrations. BHT II was identified in mats that exist within oxic to anoxic portions of the lake. However, anammox bacteria have yet to be identified in Lake Fryxell. We examine our results in the context of BHPs as biomarkers in modern and ancient environments.

}, keywords = {LTER-MCM, anammox, bacteriohopanepolyol, bacteriohopanetetrol isomer, biomarker, McMurdo Dry Valleys}, doi = {10.1111/gbi.12353}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/gbi.12353}, author = {Matys, Emily D. and Mackey, Tyler J. and Grettenberger, Christen and Mueller, Elliott and Jungblut, Anne D. and Sumner, Dawn Y. and Ian Hawes and Summons, Roger E.} } @article {4450, title = {The Geochemistry of Englacial Brine From Taylor Glacier, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {124}, year = {2019}, month = {03/2019}, abstract = {

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

}, keywords = {LTER-MCM}, doi = {10.1029/2018JG004411}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JG004411}, author = {W. Berry Lyons and Jill A. Mikucki and German, Laura A. and Kathleen A. Welch and Sue Welch and Christopher B. Gardner and Tulaczyk, Slawek M. and Pettit, Erin C. and Kowalski, Julia and Dachwald, Bernd} } @article {4373, title = {The hydroecology of an ephemeral wetland in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, year = {2019}, month = {11/2019}, abstract = {

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

}, keywords = {LTER-MCM, Antarctica, desert hydrology, diatom biodiversity, hyporheic interactions, wetlands}, doi = {10.1029/2019JG005153}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JG005153}, author = {Wlostowski, Adam and Schulte, Nicholas O. and Byron Adams and Ball, Becky and Rhea M.M. Esposito and Michael N. Gooseff and W. Berry Lyons and Uffe N. Nielsen and Ross A. Virginia and Diana H. Wall and Kathleen A. Welch and Diane M. McKnight} } @article {4164, title = {Nematodes in a polar desert reveal the relative role of biotic interactions in the coexistence of soil animals}, journal = {Communications Biology}, volume = {2}, year = {2019}, month = {02/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s42003-018-0260-y}, url = {http://www.nature.com/articles/s42003-018-0260-y}, author = {Caruso, Tancredi and Hogg, Ian D. and Uffe N. Nielsen and Bottos, Eric M. and Charles K. Lee and D. W. Hopkins and Craig S Cary and John E. Barrett and Green, T. G. Allan and Storey, Bryan C. and Diana H. Wall and Byron Adams} } @article {4374, title = {The polar regions in a 2{\textdegree}C warmer world}, journal = {Science Advances}, volume = {5}, year = {2019}, month = {12/2019}, pages = {eaaw9883}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1126/sciadv.aaw9883}, url = {http://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aaw9883}, author = {Post, Eric and Alley, Richard B. and Christensen, Torben R. and Macias-Fauria, Marc and Forbes, Bruce C. and Michael N. Gooseff and Iler, Amy and Kerby, Jeffrey T. and Laidre, Kristin L. and Mann, Michael E. and Olofsson, Johan and Stroeve, Julienne C. and Ulmer, Fran and Ross A. Virginia and Wang, Muyin} } @article {4295, title = {Soil nematode abundance and functional group composition at a global scale}, journal = {Nature}, volume = {572}, year = {2019}, month = {08/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s41586-019-1418-6}, url = {https://www.nature.com/articles/s41586-019-1418-6}, author = {van den Hoogen, Johan and Geisen, Stefan and Routh, Devin and Ferris, Howard and Traunspurger, Walter and Wardle, D and de Goede, Ron G. M. and Byron Adams and Ahmad, Wasim and Andriuzzi, Walter S. and Richard D. Bardgett and Bonkowski, Michael and Campos-Herrera, Raquel and Cares, Juvenil E. and Caruso, Tancredi and de Brito Caixeta, Larissa and Chen, Xiaoyun and Costa, Sofia R. and Creamer, Rachel and Mauro da Cunha Castro, Jos{\'e} and Dam, Marie and Djigal, Djibril and Escuer, Miguel and Griffiths, Bryan S. and Guti{\'e}rrez, Carmen and Hohberg, Karin and Kalinkina, Daria and Kardol, Paul and Kergunteuil, Alan and Korthals, Gerard and Krashevska, Valentyna and Kudrin, Alexey A. and Li, Qi and Liang, Wenju and Magilton, Matthew and Marais, Mariette and Mart{\'\i}n, Jos{\'e} Antonio Rodr{\'\i}guez and Matveeva, Elizaveta and Mayad, El Hassan and Mulder, Christian and Mullin, Peter and Neilson, Roy and Nguyen, T. A. Duong and Uffe N. Nielsen and Okada, Hiroaki and Rius, Juan Emilio Palomares and Pan, Kaiwen and Peneva, Vlada and Pellissier, Lo{\"\i}c and Carlos Pereira da Silva, Julio and Pitteloud, Camille and Powers, Thomas O. and Powers, Kirsten and Quist, Casper W. and Rasmann, Sergio and Moreno, Sara S{\'a}nchez and Scheu, Stefan and Set{\"a}l{\"a}, Heikki and Sushchuk, Anna and Tiunov, Alexei V. and Trap, Jean and van der Putten, W and Vesterg{\r a}rd, Mette and Villenave, Cecile and Waeyenberge, Lieven and Diana H. Wall and Wilschut, Rutger and Wright, Daniel G. and Yang, Jiue-in and Crowther, Thomas Ward} } @article {4196, title = {Unimodal productivity{\textendash}diversity relationships among bacterial communities in a simple polar soil ecosystem}, journal = {Environmental Microbiology}, volume = {21}, year = {2019}, month = {07/2019}, abstract = {

Unlike other macroecological principles, relationships between productivity and diversity have not been effectively tested for microbial communities. Here we describe an experiment in which the availability of resources to soil bacterial communities was manipulated in a model system, the McMurdo Dry Valleys of Antarctica. Mannitol additions were used to simulate a productivity gradient such that a response in bacterial biomass production, taxonomic diversity and functioning (e.g., enzyme activity) were induced. Resource amendment induced a positive linear response in microbial productivity (P \< 0.001) but a unimodal (hump-shaped) response in microbial diversity at multiple taxonomic scales (P = 0.035). Putative oligotrophic (e.g., phyla Nitrospirae and Cyanobacteria) and copiotrophic (e.g., phylum Proteobacteria) taxa were apparent through substantial community turnover along the resource gradient. Soil enzyme activity was inversely related to bacterial biomass but positively related to diversity, suggesting the latter may be a stronger control over enzyme-mediated decomposition. The mechanisms behind this pattern are consistent with macroecological theory of a shift from environmental (e.g., stress tolerance) to biotic (e.g., competition) drivers with increasing resource availability. This evidence is among the first of its kind to document a significant unimodal productivity\–diversity relationship for soil bacteria.

}, keywords = {LTER-MCM}, doi = {10.1111/1462-2920.14639}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/1462-2920.14639}, author = {Kevin M. Geyer and John E. Barrett} } @article {4138, title = {Barium and barite dynamics in Antarctic streams}, journal = {Geology}, volume = {46}, year = {2018}, month = {08/2018}, pages = {811 - 814}, abstract = {

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

}, keywords = {LTER-MCM}, issn = {0091-7613}, doi = {10.1130/G45048.1}, url = {https://pubs.geoscienceworld.org/gsa/geology/article/545184/Barium-and-barite-dynamics-in-Antarctic-streams}, author = {Saelens, Elsa D. and Christopher B. Gardner and Kathleen A. Welch and Sue Welch and W. Berry Lyons} } @article {4159, title = {BioTIME: A database of biodiversity time series for the Anthropocene}, journal = {Global Ecology and Biogeography}, volume = {27}, year = {2018}, month = {07/2018}, pages = {760-786}, abstract = {

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.

}, keywords = {LTER-MCM, biodiversity, global, spatial, species richness, temporal, turnover}, doi = {10.1111/geb.12729}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/geb.12729}, author = {Dornelas, Maria and Ant{\~a}o, Laura H. and Moyes, Faye and Bates, Amanda E. and Magurran, Anne E. and Adam, Du{\v s}an and Akhmetzhanova, Asem A. and Appeltans, Ward and Arcos, Jos{\'e} Manuel and Arnold, Haley and Ayyappan, Narayanan and Badihi, Gal and Baird, Andrew H. and Barbosa, Miguel and Barreto, Tiago Egydio and B{\"a}ssler, Claus and Bellgrove, Alecia and Belmaker, Jonathan and Benedetti-Cecchi, Lisandro and Bett, Brian J. and Bjorkman, Anne D. and B{\l}a{\.z}ewicz, Magdalena and Blowes, Shane A. and Bloch, Christopher P. and Bonebrake, Timothy C. and Boyd, Susan and Bradford, Matt and Brooks, Andrew J. and Brown, James H. and Bruelheide, Helge and Budy, Phaedra and Carvalho, Fernando and Casta{\~n}eda-Moya, Edward and Chen, Chaolun Allen and Chamblee, John F. and Chase, Tory J. and Siegwart Collier, Laura and Collinge, Sharon K. and Condit, Richard and Cooper, Elisabeth J. and Cornelissen, J. Hans C. and Cotano, Unai and Kyle Crow, Shannan and Damasceno, Gabriella and Davies, Claire H. and Davis, Robert A. and Day, Frank P. and Degraer, Steven and Doherty, Tim S. and Dunn, Timothy E. and Durigan, Giselda and Duffy, J. Emmett and Edelist, Dor and Edgar, Graham J. and Elahi, Robin and Elmendorf, Sarah C. and Enemar, Anders and Ernest, S. K. Morgan and Escribano, Rub{\'e}n and Estiarte, Marc and Evans, Brian S. and Fan, Tung-Yung and Turini Farah, Fabiano and Loureiro Fernandes, Luiz and Farneda, F{\'a}bio Z. and Fidelis, Alessandra and Fitt, Robert and Fosaa, Anna Maria and Daher Correa Franco, Geraldo Antonio and Frank, Grace E. and Fraser, William R. and Garc{\'\i}a, Hernando and Cazzolla Gatti, Roberto and Givan, Or and Gorgone-Barbosa, Elizabeth and Gould, William A. and Gries, Corinna and Grossman, Gary D. and Gutierr{\'e}z, Julio R. and Hale, Stephen and Harmon, Mark E. and Harte, John and Haskins, Gary and Henshaw, Donald L. and Hermanutz, Luise and Hidalgo, Pamela and Higuchi, Pedro and Hoey, Andrew and Van Hoey, Gert and Hofgaard, Annika and Holeck, Kristen and Hollister, Robert D. and Holmes, Richard and Hoogenboom, Mia and Hsieh, Chih-hao and Hubbell, Stephen P. and Huettmann, Falk and Huffard, Christine L. and Hurlbert, Allen H. and Macedo Ivanauskas, Nat{\'a}lia and Jan{\'\i}k, David and Jandt, Ute and Ja{\.z}d{\.z}ewska, Anna and Johannessen, Tore and Johnstone, Jill and Jones, Julia and Jones, Faith A. M. and Kang, Jungwon and Kartawijaya, Tasrif and Keeley, Erin C. and Kelt, Douglas A. and Kinnear, Rebecca and Klanderud, Kari and Knutsen, Halvor and Koenig, Christopher C. and Kortz, Alessandra R. and Kr{\'a}l, Kamil and Kuhnz, Linda A. and Kuo, Chao-Yang and Kushner, David J. and Laguionie-Marchais, Claire and Lancaster, Lesley T. and Min Lee, Cheol and Lefcheck, Jonathan S. and L{\'e}vesque, Esther and Lightfoot, David and Lloret, Francisco and Lloyd, John D. and L{\'o}pez-Baucells, Adri{\`a} and Louzao, Maite and Madin, Joshua S. and Magn{\'u}sson, Borg{\th}{\'o}r and Malamud, Shahar and Matthews, Iain and McFarland, Kent P. and McGill, Brian and Diane M. McKnight and McLarney, William O. and Meador, Jason and Meserve, Peter L. and Metcalfe, Daniel J. and Meyer, Christoph F. J. and Michelsen, Anders and Milchakova, Nataliya and Moens, Tom and Moland, Even and Moore, Jon and Mathias Moreira, Carolina and M{\"u}ller, J{\"o}rg and Murphy, Grace and Myers-Smith, Isla H. and Myster, Randall W. and Naumov, Andrew and Neat, Francis and Nelson, James A. and Paul Nelson, Michael and Newton, Stephen F. and Norden, Natalia and Oliver, Jeffrey C. and Olsen, Esben M. and Onipchenko, Vladimir G. and Pabis, Krzysztof and Pabst, Robert J. and Paquette, Alain and Pardede, Sinta and Paterson, David M. and P{\'e}lissier, Rapha{\"e}l and Pe{\~n}uelas, Josep and P{\'e}rez-Matus, Alejandro and Pizarro, Oscar and Pomati, Francesco and Post, Eric and Prins, Herbert H. T. and John C. Priscu and Provoost, Pieter and Prudic, Kathleen L. and Pulliainen, Erkki and Ramesh, B. R. and Mendivil Ramos, Olivia and Rassweiler, Andrew and Rebelo, Jose Eduardo and Reed, Daniel C. and Reich, Peter B. and Remillard, Suzanne M. and Richardson, Anthony J. and Richardson, J. Paul and van Rijn, Itai and Rocha, Ricardo and Rivera-Monroy, Victor H. and Rixen, Christian and Robinson, Kevin P. and Ribeiro Rodrigues, Ricardo and de Cerqueira Rossa-Feres, Denise and Rudstam, Lars and Ruhl, Henry and Ruz, Catalina S. and Sampaio, Erica M. and Rybicki, Nancy and Rypel, Andrew and Sal, Sofia and Salgado, Beatriz and Santos, Flavio A. M. and Savassi-Coutinho, Ana Paula and Scanga, Sara and Schmidt, Jochen and Schooley, Robert and Setiawan, Fakhrizal and Shao, Kwang-Tsao and Shaver, Gaius R. and Sherman, Sally and Sherry, Thomas W. and Sici{\'n}ski, Jacek and Sievers, Caya and da Silva, Ana Carolina and Rodrigues da Silva, Fernando and Silveira, Fabio L. and Slingsby, Jasper and Smart, Tracey and Snell, Sara J. and Soudzilovskaia, Nadejda A. and Souza, Gabriel B. G. and Maluf Souza, Flaviana and Castro Souza, Vin{\'\i}cius and Stallings, Christopher D. and Stanforth, Rowan and Stanley, Emily H. and Mauro Sterza, Jos{\'e} and Stevens, Maarten and Stuart-Smith, Rick and Rondon Suarez, Yzel and Supp, Sarah} } @article {4058, title = {Soil Moisture Controls the Thermal Habitat of Active Layer Soils in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {123}, year = {2018}, month = {01/2018}, chapter = {46-59}, abstract = {

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

}, keywords = {LTER-MCM}, doi = {10.1002/2017JG004018}, url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JG004018}, author = {Wlostowski, Adam and Michael N. Gooseff and Byron Adams} } @article {4139, title = {Stoichiometric Shifts in Soil C:N:P Promote Bacterial Taxa Dominance, Maintain Biodiversity, and Deconstruct Community Assemblages}, journal = {Frontiers in Microbiology}, volume = {9}, year = {2018}, month = {07/2018}, abstract = {

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

}, keywords = {LTER-MCM, ecological stoichiometry, Lake Fryxell Basin, McMurdo Dry Valleys, network community modeling, nutrient colimitation, Solirubrobacteriaceae}, doi = {10.3389/fmicb.2018.01401}, url = {https://www.frontiersin.org/article/10.3389/fmicb.2018.01401/full}, author = {Aanderud, Zachary T. and Saurey, Sabrina D. and Ball, Becky and Diana H. Wall and John E. Barrett and Muscarella, Mario E. and Griffin, Natasha A. and Ross A. Virginia and Byron Adams} } @article {4160, title = {Transit times and rapid chemical equilibrium explain chemostasis in glacial meltwater streams in the McMurdo Dry Valleys, Antarctica}, journal = {Geophysical Research Letters}, volume = {45}, year = {2018}, month = {12/2018}, pages = {13322 - 13331}, abstract = {

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

}, keywords = {LTER-MCM}, doi = {10.1029/2018GL080369}, url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL080369}, author = {Wlostowski, Adam and Michael N. Gooseff and Diane M. McKnight and W. Berry Lyons} } @article {4031, title = {Characterizing hyporheic exchange processes using high-frequency electrical conductivity-discharge relationships on subhourly to interannual timescales}, journal = {Water Resources Research}, volume = {53}, year = {2017}, month = {05/2017}, pages = {4124 - 4141}, abstract = {

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

}, keywords = {LTER-MCM}, doi = {10.1002/wrcr.v53.510.1002/2016WR019739}, url = {http://onlinelibrary.wiley.com/doi/10.1002/2016WR019739/full}, author = {Singley, Joel G. and Wlostowski, Adam and Bergstrom, Anna J. and Eric R. Sokol and Torrens, Christa L. and Chris Jaros and Wilson, Colleen E. and Hendrickson, Patrick J. and Michael N. Gooseff} } @article {4112, title = {A communal catalogue reveals Earth{\textquoteright}s multiscale microbial diversity}, journal = {Nature}, volume = {551}, year = {2017}, month = {11/2017}, chapter = {457}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/nature24621}, url = {https://www.nature.com/articles/nature24621}, author = {Thompson, Luke R. and Sanders, Jon G. and McDonald, Daniel and Amir, Amnon and Ladau, Joshua and Locey, Kenneth J. and Prill, Robert J. and Tripathi, Anupriya and Gibbons, Sean M. and Ackermann, Gail and Navas-Molina, Jose A. and Janssen, Stefan and Kopylova, Evguenia and V{\'a}zquez-Baeza, Yoshiki and Antonio Gonz{\'a}lez and Morton, James T. and Mirarab, Siavash and Zech Xu, Zhenjiang and Jiang, Lingjing and Haroon, Mohamed F. and Kanbar, Jad and Zhu, Qiyun and Jin Song, Se and Kosciolek, Tomasz and Bokulich, Nicholas A. and Lefler, Joshua and Brislawn, Colin J. and Humphrey, Gregory and Owens, Sarah M. and Hampton-Marcell, Jarrad and Berg-Lyons, Donna and McKenzie, Valerie and Noah Fierer and Fuhrman, Jed A. and Clauset, Aaron and Stevens, Rick L. and Shade, Ashley and Pollard, Katherine S. and Goodwin, Kelly D. and Jansson, Janet K. and Gilbert, Jack A. and Knight, Rob and The Earth Microbiome Project Consortium} } @article {4022, title = {Decadal ecosystem response to an anomalous melt season in a polar desert in Antarctica}, journal = {Nature Ecology \& Evolution}, volume = {1}, year = {2017}, month = {09/2017}, pages = {1334-1338}, keywords = {LTER-MCM}, doi = {10.1038/s41559-017-0253-0}, url = {https://www.nature.com/articles/s41559-017-0253-0}, author = {Michael N. Gooseff and John E. Barrett and Byron Adams and Peter T. Doran and Andrew G Fountain and W. Berry Lyons and Diane M. McKnight and John C. Priscu and Eric R. Sokol and Cristina D. Takacs-Vesbach and Martijn L. Vandegehuchte and Ross A. Virginia and Diana H. Wall} } @article {4019, title = {Diversity and Distribution of Freshwater Aerobic Anoxygenic Phototrophic Bacteria across a Wide Latitudinal Gradient}, journal = {Frontiers in Microbiology}, volume = {8}, year = {2017}, month = {02/2017}, abstract = {

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).

}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2017.00175}, url = {http://journal.frontiersin.org/article/10.3389/fmicb.2017.00175/full}, author = {Ferrera, Isabel and Sarmento, Hugo and John C. Priscu and Amy Chiuchiolo and Jos{\'e} M. Gonz{\'a}lez and Grossart, Hans-Peter} } @article {4111, title = {Early diverging lineages within Cryptomycota and Chytridiomycota dominate the fungal communities in ice-covered lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Scientific Reports}, volume = {7}, year = {2017}, month = {11/2017}, chapter = {15348}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s41598-017-15598-w}, url = {https://www.nature.com/articles/s41598-017-15598-w}, author = {Rojas-Jimenez, Keilor and Wurzbacher, Christian and Bourne, Elizabeth Charlotte and Amy Chiuchiolo and John C. Priscu and Grossart, Hans-Peter} } @article {4101, title = {High-resolution elevation mapping of the McMurdo Dry Valleys, Antarctica, and surrounding regions}, journal = {Earth System Science Data}, volume = {9}, year = {2017}, month = {07/2017}, pages = {435 - 443}, abstract = {

We present detailed surface elevation measurements for the McMurdo Dry Valleys, Antarctica derived from aerial lidar surveys flown in the austral summer of 2014\–2015 as part of an effort to understand geomorphic changes over the past decade. Lidar return density varied from 2 to \> 10 returns m\−2\ with an average of about 5 returns m\−2. Vertical and horizontal accuracies are estimated to be 7 and 3 cm, respectively. In addition to our intended targets, other ad hoc regions were also surveyed including the Pegasus flight facility and two regions on Ross Island, McMurdo Station, Scott Base (and surroundings), and the coastal margin between Cape Royds and Cape Evans. These data are included in this report and data release. The combined data are freely available at\ https://doi.org/10.5069/G9D50JX3.

}, keywords = {LTER-MCM}, doi = {10.5194/essd-9-435-2017}, url = {https://www.earth-syst-sci-data.net/9/435/2017/essd-9-435-2017.pdf}, author = {Andrew G Fountain and Fernandez-Diaz, Juan C. and Maciek K. Obryk and Joseph S. Levy and Michael N. Gooseff and David J. Van Horn and Morin, P and Shrestha, Ramesh} } @article {4023, title = {Hydrologic connectivity and implications for ecosystem processes - Lessons from naked watersheds}, journal = {Geomorphology}, volume = {277}, year = {2017}, month = {01/2017}, pages = {63 - 71}, abstract = {

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

}, keywords = {LTER-MCM}, issn = {0169555X}, doi = {10.1016/j.geomorph.2016.04.024}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0169555X16302483}, author = {Michael N. Gooseff and Wlostowski, Adam and Diane M. McKnight and Chris Jaros} } @phdthesis {4161, title = {Hydrologic connectivity in the McMurdo Dry Valleys, Antarctica: Water-mediated mass and energy fluxes in streams and soils}, volume = {Ph.D.}, year = {2017}, school = {University of Colorado Boulder}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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

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

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

}, keywords = {LTER-MCM}, url = {https://scholar.colorado.edu/cven_gradetds/77/}, author = {Wlostowski, Adam and Michael N. Gooseff} } @article {4032, title = {Impacts of permafrost degradation on a stream in Taylor Valley, Antarctica}, journal = {Geomorphology}, volume = {285}, year = {2017}, month = {05/2017}, pages = {205 - 213}, abstract = {

The McMurdo Dry Valleys (MDV) of Antarctica are an ice-free landscape that supports a complex, microbially dominated ecosystem despite a severely arid, cold environment (b 5 cm water equivalent/y, \− 18 \°C mean annual air temperature). Recent observations of permafrost degradation in the coastal zones of the MDV suggest that this region is nearing a threshold of rapid landscape change. In 2012, substantial thermokarst development was observed along several kilometers of the west branch of Crescent Stream in Taylor Valley mostly in the form of bank failures, whereas the adjacent east branch was unaffected. The objective of this study was to quantify the changes to the stream banks of the west branch of Crescent Stream and to determine the impacts on the composition of the stream bed material. Three annually repeated terrestrial LiDAR scans were compared to determine the rates of ground surface change caused by thermokarst formation on the stream bank. The areal extent of the thermokarst was shown to be decreasing; however, the average vertical rate of retreat remained constant. Field measurements of bed materials indicated that the west branch and the reach downstream of the confluence (of east and west branches) consistently contained more fines than the unaffected east branch. This suggests that the finer bed material is a result of the thermokarst development on the west branch. These finer bed material compositions are likely to increase the mobility of the bed material, which will have implications for stream morphology, stream algal mat communities, and downstream aquatic ecosystems.

}, keywords = {LTER-MCM}, doi = {10.1016/j.geomorph.2017.02.009}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0169555X16308467}, author = {Sudman, Zachary and Michael N. Gooseff and Andrew G Fountain and Joseph S. Levy and Maciek K. Obryk and David J. Van Horn} } @article {4021, title = {Primary productivity as a control over soil microbial diversity along environmental gradients in a polar desert ecosystem}, journal = {PeerJ}, volume = {5}, year = {2017}, month = {07/2017}, pages = {e3377}, abstract = {

Primary production is the fundamental source of energy to foodwebs and ecosystems, and is thus an important constraint on soil communities. This coupling is particularly evident in polar terrestrial ecosystems where biological diversity and activity is tightly constrained by edaphic gradients of productivity (e.g., soil moisture, organic carbon availability) and geochemical severity (e.g., pH, electrical conductivity). In the McMurdo Dry Valleys of Antarctica, environmental gradients determine numerous properties of soil communities and yet relatively few estimates of gross or net primary productivity (GPP, NPP) exist for this region. Here we describe a survey utilizing pulse amplitude modulation (PAM) fluorometry to estimate rates of GPP across a broad environmental gradient along with belowground microbial diversity and decomposition. PAM estimates of GPP ranged from an average of 0.27 mmol O2/m2/s in the most arid soils to an average of 6.97 mmol O2/m2/s in the most productive soils, the latter equivalent to 217 g C/m2/y in annual NPP assuming a 60 day growing season. A diversity index of four carbon-acquiring enzyme activities also increased with soil productivity, suggesting that the diversity of organic substrates in mesic environments may be an additional driver of microbial diversity. Overall, soil productivity was a stronger predictor of microbial diversity and enzymatic activity than any estimate of geochemical severity. These results highlight the fundamental role of environmental gradients to control community diversity and the dynamics of ecosystem-scale carbon pools in arid systems.\ 

}, keywords = {LTER-MCM}, doi = {10.7717/peerj.3377}, url = {https://peerj.com/articles/3377/}, author = {Kevin M. Geyer and Cristina D. Takacs-Vesbach and Michael N. Gooseff and John E. Barrett} } @article {4018, title = {Thermal autecology describes the occurrence patterns of four benthic diatoms in McMurdo Dry Valley streams}, journal = {Polar Biology}, volume = {40}, year = {2017}, month = {06/2017}, pages = {2381-2396}, abstract = {

Benthic microbial mats in the glacial-fed melt- water streams are hotspots of productivity in the McMurdo Dry Valleys (MDV), Antarctica. Benthic diatoms are common in these mats and the[45 primarily endemic taxa represent the most diverse group of eukaryotes in the MDV. In this harsh polar desert, streams are thermally dynamic with daily water temperatures varying 6\–9 \°C and daily maximum temperatures as high as 15 \°C. Stream temperature may play a role in determining growth rates and survival strategies. To understand taxon-specific adaptations to their environment, we measured the growth rates of unialgal cultures of four diatom taxa (Psammothidium papilio, Hantzschia abundans, Hantzschia amphioxys, and Hantzschia amphioxys f. muelleri) under three temperature conditions (7.6, 10, and 15 \°C) that were representative of maximum daily stream temperatures. We found that P. papilio exhibited a constant growth rate across the full temperature range; this species is most common in streams that begin to flow early in the summer and with less variable thermal regimes. Growth rates for H. abundans were greatest at 15 \°C, but showed a non-linear relationship with temperature. H. amphioxys f. muelleri

grew faster than the other taxa studied and thrived at 10 \°C. Hantzschia amphioxys grew only at the two lower temperatures. These results aligned with the observed relationships between each taxon\’s relative abundance and stream temperatures in the long-term record maintained by the MDV Long-Term Ecological Research program. Overall, our observations suggest that differences in thermal optima may be one factor contributing to and maintaining the diversity of benthic diatom flora in the MDV.
}, keywords = {LTER-MCM}, doi = {10.1007/s00300-017-2151-y}, url = {https://link.springer.com/article/10.1007/s00300-017-2151-y}, author = {Darling, Joshua P. and Garland, Deena D. and Lee F. Stanish and Rhea M.M. Esposito and Eric R. Sokol and Diane M. McKnight} } @article {3713, title = {Aerobiology Over Antarctica {\textendash} A New Initiative for Atmospheric Ecology}, journal = {Frontiers in Microbiology}, volume = {776796194610314927235011365134445142846479110123936574}, year = {2016}, month = {02/2016}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2016.00016}, url = {http://journal.frontiersin.org/Article/10.3389/fmicb.2016.00016/abstract}, author = {Pearce, David A. and Alekhina, Irina A. and Terauds, Aleks and Wilmotte, Annick and Quesada, Antonio and Edwards, Arwyn and Dommergue, Aurelien and Sattler, Birgit and Byron Adams and Magalhaes, Catarina and Chu, Wan-Loy and Lau, Maggie C. Y. and Craig S Cary and Smith, David J. and Diana H. Wall and Eguren, Gabriela and Matcher, Gwynneth and Bradley, James A. and de Vera, Jean-Pierre and Elster, Josef and Hughes, Kevin A. and Cuthbertson, Lewis and Benning, Liane G. and Gunde-Cimerman, Nina and Convey, Peter and Hong, Soon Gyu and Pointing, Steve B. and Pellizari, Vivian H. and Vincent, Warwick F.} } @article {3951, title = {Hydrological Controls on Ecosystem Dynamics in Lake Fryxell, Antarctica}, journal = {PLOS ONE}, volume = {11}, year = {2016}, month = {07/2016}, pages = {e0159038}, keywords = {LTER-MCM}, doi = {10.1371/journal.pone.015903810.1371}, url = {http://dx.plos.org/10.1371/journal.pone.0159038}, author = {Herbei, Radu and Rytel, Alexander L. and W. Berry Lyons and Diane M. McKnight and Chris Jaros and Michael N. Gooseff and John C. Priscu}, editor = {Hewitt, Judi} } @article {4102, title = {The Impact of a Large-Scale Climate Event on Antarctic Ecosystem Processes}, journal = {BioScience}, volume = {66}, year = {2016}, month = {10/2016}, pages = {848 - 863}, abstract = {

Extreme climate and weather events, such as a drought, hurricanes, or ice storms, can strongly imprint ecosystem processing and may alter ecosystem structure. Ecosystems in extreme environments are particularly vulnerable because of their adaptation to severe limitations in energy, water, or nutrients. The vulnerability can be expressed as a relatively long-lasting ecosystem response to a small or brief change in environmental conditions. Such an event occurred in Antarctica and affected two vastly different ecosystems: a marine-dominated coastal system and a terrestrial polar desert. Both sites experienced winds that warmed air temperatures above the 0\°C threshold, resulting in extensive snow and ice melt and triggering a series of cascading effects through the ecosystems that are continuing to play out more than a decade later. This highlights the sensitivity of Antarctic ecosystems to warming events, which should occur more frequently in the future with global climate warming.

}, keywords = {LTER-MCM}, issn = {0006-3568}, doi = {10.1093/biosci/biw110}, url = {http://academic.oup.com/bioscience/article-pdf/66/10/848/7510601/biw110.pdf}, author = {Andrew G Fountain and Saba, Grace and Byron Adams and Peter T. Doran and Fraser, William and Michael N. Gooseff and Maciek K. Obryk and John C. Priscu and Sharon E. Stammerjohn and Ross A. Virginia} } @article {3961, title = {Lake Vanda: A sentinel for climate change in the McMurdo Sound Region of Antarctica}, journal = {Global and Planetary Change}, volume = {144}, year = {2016}, month = {Jan-09-2016}, pages = {213 - 227}, abstract = {

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, f{\"o}hn 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.

}, keywords = {LTER-MCM}, issn = {09218181}, doi = {10.1016/j.gloplacha.2016.06.007}, url = {http://www.sciencedirect.com/science/article/pii/S092181811530014X}, author = {Castendyk, Devin and Maciek K. Obryk and Leidman, Sasha Z. and Michael N. Gooseff and Ian Hawes} } @article {3952, title = {Microbial Community Responses to Increased Water and Organic Matter in the Arid Soils of the McMurdo Dry Valleys, Antarctica}, journal = {Frontiers in Microbiology}, volume = {7}, year = {2016}, month = {07/2016}, chapter = {1040}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2016.01040}, url = {http://journal.frontiersin.org/article/10.3389/fmicb.2016.01040}, author = {Heather N. Buelow and Winter, Ara S. and David J. Van Horn and John E. Barrett and Michael N. Gooseff and Schwartz, Egbert and Cristina D. Takacs-Vesbach} } @article {3710, title = {Microbial Mat Communities along an Oxygen Gradient in a Perennially Ice-Covered Antarctic Lake}, journal = {Applied and Environmental Microbiology}, volume = {82}, year = {2016}, month = {01/2016}, pages = {620 - 630}, keywords = {LTER-MCM}, issn = {0099-2240}, doi = {10.1128/AEM.02699-15}, url = {http://aem.asm.org/lookup/doi/10.1128/AEM.02699-15}, author = {Jungblut, Anne D. and Ian Hawes and Mackey, Tyler J. and Krusor, Megan and Peter T. Doran and Sumner, Dawn Y. and Eisen, Jonathan A. and Hillman, Colin and Goroncy, Alexander K.}, editor = {Stams, A. J.} } @article {3718, title = {Patterns of hydrologic connectivity in the McMurdo dry valleys, Antarctica: a synthesis of 20 years of hydrologic data}, journal = {Hydrological Processes}, volume = {30}, year = {2016}, month = {04/2016}, pages = {2958-2975}, chapter = {2958}, abstract = {

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

}, keywords = {LTER-MCM}, doi = {10.1002/hyp.10818}, url = {http://onlinelibrary.wiley.com/doi/10.1002/hyp.10818}, author = {Wlostowski, Adam and Michael N. Gooseff and Diane M. McKnight and Chris Jaros and W. Berry Lyons} } @article {4030, title = {Responses of Antarctic Marine and Freshwater Ecosystems to Changing Ice Conditions}, journal = {BioScience}, volume = {66}, year = {2016}, month = {Jan-10-2016}, pages = {864 - 879}, keywords = {LTER-MCM}, issn = {0006-3568}, doi = {10.1093/biosci/biw109}, url = {https://academic.oup.com/bioscience/article-lookup/doi/10.1093/biosci/biw109https://academic.oup.com/bioscience/article/66/10/864/2415532/Responses-of-Antarctic-Marine-and-Freshwater}, author = {Maciek K. Obryk and Peter T. Doran and Friedlaender, Ari S. and Michael N. Gooseff and Li, Wei and Rachael M. Morgan-Kiss and John C. Priscu and Schofield, Oscar and Sharon E. Stammerjohn and Steinberg, Deborah K. and Hugh W. Ducklow} } @article {3875, title = {Stream biogeochemical and suspended sediment responses to permafrost degradation in stream banks in Taylor Valley, Antarctica}, journal = {Biogeosciences}, volume = {13}, year = {2016}, month = {03/2016}, pages = {1723 - 1732}, abstract = {

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

}, keywords = {LTER-MCM}, doi = {10.5194/bg-13-1723-2016}, url = {http://www.biogeosciences.net/13/1723/2016/bg-13-1723-2016.pdf}, author = {Michael N. Gooseff and David J. Van Horn and Sudman, Zachary and Diane M. McKnight and Kathleen A. Welch and W. Berry Lyons} } @article {3204, title = {Comparison of arsenic and molybdenum geochemistry in meromictic lakes of the McMurdo Dry Valleys, Antarctica: Implications for oxyanion-forming trace element behavior in permanently stratified lakes}, journal = {Chemical Geology}, volume = {404}, year = {2015}, month = {05/2015}, pages = {110 - 125}, chapter = {110}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {00092541}, doi = {10.1016/j.chemgeo.2015.03.029}, url = {http://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/plain}, author = {Yang, Ningfang and Kathleen A. Welch and Mohajerin, T. Jade and Telfeyan, Katherine and Chevis, Darren A. and Grimm, Deborah A. and W. Berry Lyons and White, Christopher D. and Johannesson, Karen H.} } @article {3475, title = {Fostering ecological data sharing: collaborations in the International Long Term Ecological Research Network}, journal = {Ecosphere}, volume = {6}, year = {2015}, month = {10/2015}, abstract = {

The International Long Term Ecological Research (ILTER) Network was established in 1993 and is now composed of thirty-eight national networks representing a diversity of ecosystems around the globe. Data generated by the ILTER Network are valuable for scientists addressing broad spatial and temporal scale research questions, but only if these data can be easily discovered, accessed, and understood. Challenges to publishing ILTER data have included unequal distribution among networks of information management expertise, user-friendly tools, and resources. Language and translation have also been issues. Despite these significant obstacles, ILTER information managers have formed grassroots partnerships and collaborated to provide information management training, adopt a common metadata standard, develop information management tools useful throughout the network, and organize scientist/information manager workshops that encourage scientists to share and integrate data. Throughout this article, we share lessons learned from the successes of these grassroots international partnerships to inform others who wish to collaborate internationally on projects that depend on data sharing entailing similar management challenges.

}, keywords = {LTER-MCM}, issn = {2150-8925}, doi = {10.1890/ES14-00281.1}, url = {http://www.esajournals.org/doi/10.1890/ES14-00281.1}, author = {Vanderbilt, Kristin L. and Lin, Chau-Chin and Lu, Sheng-Shan and Kassim, Abd Rahman and He, Honglin and Guo, Xuebing and Inigo San Gil and Blankman, David and Porter, John H.} } @article {3715, title = {Global environmental change and the nature of aboveground net primary productivity responses: insights from long-term experiments}, journal = {Oecologia}, volume = {177}, year = {2015}, month = {04/2015}, pages = {935 - 947}, keywords = {LTER-MCM}, issn = {0029-8549}, doi = {10.1007/s00442-015-3230-9}, url = {http://link.springer.com/10.1007/s00442-015-3230-9http://link.springer.com/content/pdf/10.1007/s00442-015-3230-9}, author = {Smith, Melinda D. and La Pierre, Kimberly J. and Collins, SL and Knapp, Alan K. and Gross, Katherine L. and John E. Barrett and Frey, Serita D. and Gough, Laura and Miller, Robert J. and Morris, James T. and Rustad, Lindsey E. and Yarie, John} } @mastersthesis {4192, title = {The impacts of thermokarst activity on a stream in the McMurdo Dry Valleys}, volume = {M.S.}, year = {2015}, month = {2015}, pages = {70}, school = {University of Colorado}, type = {masters}, address = {Boulder, CO}, abstract = {

The McMurdo Dry Valleys (MDV) of Antarctica are a unique ice-free landscape that is host to vibrant ecosystems despite the harsh environment (\<10 cm water equivalent/yr, -20\°C mean air temperature). Aquatic ecosystems in the MDV are dependent on the ephemeral glacial runoff streams which feed the closed basin perennially ice covered lakes. The upland zones of the Dry Valleys have been shown to have some of the slowest ground surface change rates in the world. However, recent observations in the coastal valley transition zones suggest that this area may be nearing a threshold of rapid landscape change.

One of the recent observations that supports this idea is the discovery of extensive thermokarst degradation (permafrost thaw features) along the banks of Crescent Stream in Taylor Valley. In 2012, a large stretch of the West Branch of Crescent Stream was found to have significant thermokarst bank failures, while the adjacent East Branch was found to be unaffected. The thermokarst impacts within this setting are important to understand because of the disturbances that massive sediment loading can impose on downstream biological communities.

Annually repeated terrestrial LiDAR scans (3) were compared to determine the rates of ground surface change due to thermokarst degradation. It was found that the areal extent of the thermokarst was decreasing, however the average linear rates of retreat remained constant. Field measurements including, pebble counts, fine sediment counts, and sieve samples were analyzed to determine the effects of the thermokarst on the stream bed material. It was found that the West Branch and the reach downstream of the confluence were consistently finer than the unaffected East Branch. This suggests that the finer bed material is due to the thermokarst bank degradation. Stream power was calculated for multiple reaches to be used as a metric for the mobilization of the streambed material. It was found that both branches infrequently experience flows substantial enough to mobilize the bed material. Even the finer bed material of the impacted West Branch reach required flows that had a 5 \% chance of exceedance for mobilization of the bed. These findings suggest the West Branch of Crescent Stream and the biota supported by this branch of the stream, continue to adjust to the sediment introduced from the thermokarst bank degradation.

}, keywords = {LTER-MCM, Antarctica, Dry valleys, earth sciences, stream, thermokarst}, url = {https://search.proquest.com/docview/1717582573}, author = {Sudman, Zachary and Michael N. Gooseff} } @article {3716, title = {Mitochondrial DNA analyses reveal widespread tardigrade diversity in Antarctica}, journal = {Invertebrate Systematics}, volume = {29}, year = {2015}, month = {12/2015}, pages = {578}, keywords = {LTER-MCM}, issn = {1445-5226}, doi = {10.1071/IS14019}, url = {http://www.publish.csiro.au/?paper=IS14019}, author = {Velasco-Castrillon, Alejandro and McInnes, Sandra J. and Schultz, Mark B. and Arroniz-Crespo, Maria and D{\textquoteright}Haese, Cyrille A. and Gibson, John A. E. and Byron Adams and Page, Timothy J. and Austin, Andrew D. and Cooper, Steven J. B. and Stevens, Mark I.} } @article {3522, title = {Niche and metabolic principles explain patterns of diversity and distribution: theory and a case study with soil bacterial communities}, journal = {Proceedings of the Royal Society B: Biological Sciences}, volume = {282}, year = {2015}, month = {05/2015}, pages = {2630}, abstract = {

The causes of biodiversity patterns are controversial and elusive due to complex environmental variation, covarying changes in communities, and lack of baseline and null theories to differentiate straightforward causes from more complex mechanisms. To address these limitations, we developed general diversity theory integrating metabolic principles with niche-based community assembly. We evaluated this theory by investigating patterns in the diversity and distribution of soil bacteria taxa across four orders of magnitude variation in spatial scale on an Antarctic mountainside in low complexity, highly oligotrophic soils. Our theory predicts that lower temperatures should reduce taxon niche widths along environmental gradients due to decreasing growth rates, and the changing niche widths should lead to contrasting α- and β-diversity patterns. In accord with the predictions, α-diversity, niche widths and occupancies decreased while β-diversity increased with increasing elevation and decreasing temperature. The theory also successfully predicts a hump-shaped relationship between α-diversity and pH and a negative relationship between α-diversity and salinity. Thus, a few simple principles explained systematic microbial diversity variation along multiple gradients. Such general theory can be used to disentangle baseline effects from more complex effects of temperature and other variables on biodiversity patterns in a variety of ecosystems and organisms.

}, keywords = {LTER-MCM}, issn = {0962-8452}, doi = {10.1098/rspb.2014.2630}, url = {http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2014.2630}, author = {Okie, Jordan G. and David J. Van Horn and Storch, David and John E. Barrett and Michael N. Gooseff and Kopsova, Lenka and Cristina D. Takacs-Vesbach} } @article {3712, title = {Potential for real-time understanding of coupled hydrologic and biogeochemical processes in stream ecosystems: Future integration of telemetered data with process models for glacial meltwater streams}, journal = {Water Resources Research}, volume = {51}, year = {2015}, month = {08/2015}, pages = {6725 - 6738}, keywords = {LTER-MCM}, doi = {10.1002/2015WR017618}, url = {http://doi.wiley.com/10.1002/2015WR017618http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002\%2F2015WR017618}, author = {Diane M. McKnight and Cozzetto, K and Cullis, James D.S. and Michael N. Gooseff and Chris Jaros and Koch, J. and W. Berry Lyons and Neupauer, R. M. and Wlostowski, Adam} } @article {3215, title = {Recovery of Antarctic stream epilithon from simulated scouring events}, journal = {Antarctic Science}, volume = {27}, year = {2015}, month = {Jan-08-2015}, pages = {341 - 354}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0954-1020}, doi = {10.1017/S0954102015000024}, url = {http://www.journals.cambridge.org/abstract_S0954102015000024}, author = {Tyler J. Kohler and Ethan Chatfield and Michael N. Gooseff and John E. Barrett and Diane M. McKnight} } @article {3222, title = {A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond}, journal = {Antarctic Science}, volume = {27}, year = {2015}, month = {Jan-02-2015}, pages = {3 - 18}, abstract = {

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

}, keywords = {LTER-MCM}, issn = {0954-1020}, doi = {10.1017/S0954102014000674}, url = {http://www.journals.cambridge.org/abstract_S0954102014000674}, author = {Kennicutt, M.C. and Steven L. Chown and Cassano, J.J. and Liggett, D. and Lloyd S. Peck and Massom, R. and Rintoul, S.R. and Storey, J. and Vaughan, D.G. and Wilson, T.J. and Allison, I. and Ayton, J. and Badhe, R. and Baeseman, J. and Barrett, P.J. and Elanor R. Bell and Bertler, N. and Bo, S. and Brandt, A. and David Bromwich and Craig S Cary and Clark, M.S. and Peter Convey and Costa, E.S. and Cowan, D. and Deconto, R. and Dunbar, R. and Elfring, C. and Escutia, C. and Francis, J. and Fricker, H.A. and Fukuchi, M. and Gilbert, N. and Gutt, J. and Havermans, C. and Hik, D. and Hosie, G. and Jones, C. and Kim, Y.D. and Le Maho, Y. and Lee, S.H. and Leppe, M. and Leitchenkov, G. and Li, X. and Lipenkov, V. and Lochte, K. and L{\'o}pez-Mart{\'\i}nez, J. and {\"u}decke, C. and W. Berry Lyons and Marenssi, S. and Miller, H. and Morozova, P. and Naish, T. and Nayak, S. and Ravindra, R. and Retamales, J. and Ricci, C.A. and Rogan-Finnemore, M. and Ropert-Coudert, Y. and Samah, A.A. and Sanson, L. and Scambos, T. and I.R. Schloss and Shiraishi, K. and Siegert, M.J. and Sim{\~o}es, J.C. and Storey, B. and Sparrow, M.D. and Diana H. Wall and Walsh, J.C. and Wilson, G. and Winther, J.G. and J.C. Xavier and Yang, H. and Sutherland, W.J.} } @article {1066, title = {Spatiotemporal Dynamics of Wetted Soils across a Polar Desert Landscape, McMurdo Dry Valleys Antarctica}, journal = {Antarctic Science}, volume = {27}, year = {2015}, month = {04/2015}, pages = {197-209}, chapter = {197}, abstract = {Liquid water is scarce across the landscape of the McMurdo Dry Valleys (MDV), Antarctica, a 3800 km2 ice-free region, and is chiefly associated with soils that are adjacent to streams and lakes (i.e. wetted margins) during the annual thaw season. However, isolated wetted soils have been observed at locations distal from water bodies. The source of water for the isolated patches of wet soil is potentially generated by a combination of infiltration from melting snowpacks, melting of pore ice at the ice table, and melting of buried segregation ice formed during winter freezing. High resolution remote sensing data gathered several times per summer in the MDV region were used to determine the spatial and temporal distribution of wet soils. The spatial consistency with which the wet soils occurred was assessed for the 2009{\textendash}10 to 2011{\textendash}12 summers. The remote sensing analyses reveal that cumulative area and number of wet soil patches varies among summers. The 2010{\textendash}11 summer provided the most wetted soil area (10.21 km2) and 2009{\textendash}10 covered the least (5.38 km2). These data suggest that wet soils are a significant component of the MDV cold desert land system and may become more prevalent as regional climate changes.}, keywords = {LTER-MCM}, doi = {10.1017/S0954102014000601}, url = {http://dx.doi.org/10.1017/S0954102014000601}, author = {Langford, Z. L. and Michael N. Gooseff and Lampkin, Derrick J.} } @article {1054, title = {Bacterial community composition of divergent soil habitats from a polar desert.}, journal = {FEMS Microbiology Ecology}, volume = {89}, year = {2014}, month = {08/2014}, pages = {490-494}, type = {Short Communication}, chapter = {490}, abstract = {Edaphic factors such as pH, organic matter, and salinity are often the most significant drivers of diversity patterns in soil bacterial communities. Desert ecosystems in particular are model locations for examining such relationships as food web complexity is low and the soil environment is biogeochemically heterogeneous. Here, we present the findings from a 16S rRNA gene sequencing approach used to observe the differences in diversity and community composition among three divergent soil habitats of the McMurdo Dry Valleys, Antarctica. Results show that alpha diversity is significantly lowered in high pH soils, which contain higher proportions of the phyla Acidobacteria and Actinobacteria, while mesic soils with higher soil organic carbon (and ammonium) content contain high proportions of Nitrospira, a nitrite-oxidizing bacteria. Taxonomic community resolution also had a significant impact on our conclusions, as pH was the primary predictor of phylum-level diversity, while moisture was the most significant predictor of diversity at the genus level. Predictive power also increased with increasing taxonomic resolution, suggesting a potential increase in nic}, keywords = {LTER-MCM}, doi = {10.1111/1574-6941.12306}, author = {Kevin M. Geyer and Adam E. Altrichter and Cristina D. Takacs-Vesbach and Michael N. Gooseff and John E. Barrett} } @article {1055, title = {Characterization of Growing Bacterial Populations in McMurdo Dry Valley Soils through Stable Isotope Probing with 18O-water.}, journal = {FEMS Microbiology Ecology.}, volume = {89}, year = {2014}, month = {08/2014}, pages = {415-425}, chapter = {415}, abstract = {Soil microbial communities of the McMurdo Dry Valleys, Antarctica (MDV) contain representatives from at least fourteen bacterial phyla. However, given low rates of microbial activity, it is unclear whether this richness represents functioning rather than dormant members of the community. We used stable isotope probing (SIP) with (18) O-water to determine if microbial populations grow in MDV soils. Changes in the microbial community were characterized in soils amended with H2 (18) O and H2 (18) O-organic matter. Sequencing the 16S rRNA genes of the heavy and light fractions of the bacterial community DNA shows that DNA of microbial populations was labeled with (18) O-water, indicating these micro-organisms grew in the MDV soils. Significant differences existed in the community composition of the heavy and light fractions of the H2 (18) O and H2 (18) O-organic matter amended samples (Anosim P < 0.05 of weighted Unifrac distance). Control samples and the light DNA fraction of the H2 (18) O amended samples were dominated by representatives of the phyla Deinococcus-Thermus, Proteobacteria, Planctomyces, Gemmatimonadetes, Actinobacteria and Acidobacteria, whereas Proteobacteria were more prevalent in the heavy DNA fractions from the H2 (18) O-water and the H2 (18) O-water-organic matter treatments. Our results indicate that SIP with H2 (18) O can be used to distinguish active bacterial populations even in this low organic matter environment.}, keywords = {LTER-MCM}, doi = {10.1111/1574-6941.12349}, author = {Schwartz, E. and David J. Van Horn and Heather N. Buelow and Michael N. Gooseff and John E. Barrett and Cristina D. Takacs-Vesbach and Okie, J.G.} } @phdthesis {4086, title = {Environmental Controls Over the Distribution and Function of Antarctic Soil Bacterial Communities}, volume = {Ph.D.}, year = {2014}, school = {Virginia Tech}, type = {doctoral}, address = {Blacksburg, VA}, abstract = {

Microbial community composition plays a vital role in soil biogeochemical cycling. Information that explains the biogeography of microorganisms is consequently necessary for predicting the timing and magnitude of important ecosystem services mediated by soil biota, such as decomposition and nutrient cycling. Theory developed to explain patterns in plant and animal distributions such as the prevalent relationship between ecosystem productivity and diversity may be successfully extended to microbial systems and accelerate an emerging ecological understanding of the \"unseen majority.\" These considerations suggest a need to define the important mechanisms which affect microbial biogeography as well as the sensitivity of community structure/function to changing climatic or environmental conditions. To this end, my dissertation covers three data chapters in which I have 1) examined patterns in bacterial biogeography using gradients of environmental severity and productivity to identify changes in community diversity (e.g. taxonomic richness) and structure (e.g. similarity); 2) detected potential bacterial ecotypes associated with distinct soil habitats such as those of high alkalinity or electrical conductivity and; 3) measured environmental controls over the function (e.g. primary production, exoenzyme activity) of soil organisms in an environment of severe environmental limitations. Sampling was performed in the polar desert of Antarctica\&$\#$39;s McMurdo Dry Valleys, a model ecosystem which hosts microbially-dominated soil foodwebs and displays heterogeneously distributed soil properties across the landscape. Results for Chapter 2 indicate differential effects of resource availability and geochemical severity on bacterial communities,\ with a significant productivity-diversity relationship that plateaus near the highest observed concentrations of the limiting resource organic carbon (0.30mg C/g soil). Geochemical severity (e.g. pH, electrical conductivity) primarily affected bacterial community similarity and successfully explained the divergent structure of a subset of samples. 16S rRNA amplicon pyrosequencing further revealed in Chapter 3 the identity of specific phyla that preferentially exist within certain habitats (i.e.\ Acidobacteria\ in alkaline soils,\ Nitrospira\ in mesic soils) suggesting the presence of niche specialists and spatial heterogeneity of taxa-specific functions (i.e. nitrite oxidation). Additionally, environmental parameters had different explanatory power towards predicting bacterial richness at varying taxonomic scales, from 57\% of phylum-level richness with pH to 91\% of order- and genus-level richness with moisture. Finally, Chapter 4 details a simultaneous sampling of soil communities and their associated ecosystem functions (primary productivity, enzymatic decomposition) and indicates that the overall organic substrate diversity may be greater in mesic soils where bacterial diversity is also highest, thus a potentially unforeseen driver of community dynamics. I also quantified annual rates of soil production which range between 0.7 - 18.1g C/m2/yr from the more arid to productive soils, respectively. In conclusion, the extension of biogeographical theory for macroorganisms has proven successful and both environmental severity and resource availability have obvious (although different) effects on the diversity and composition of soil microbial communities.

}, keywords = {LTER-MCM, biogeochemistry, biogeography, McMurdo Dry Valleys, microbial ecology, productivity/diversity theory}, url = {http://hdl.handle.net/10919/64417}, author = {Kevin M. Geyer}, editor = {John E. Barrett} } @article {1059, title = {Estimating photosynthetic activity in microbial mats in an ice-covered Antarctic lake using automated oxygen microelectode profiling and variable chlorophyll fluorescence}, journal = {Limnology and Oceanography}, volume = {59}, year = {2014}, month = {08/2014}, pages = {674-688}, chapter = {674}, abstract = { An automated oxygen microprofiler measured a positive flux of oxygen from microbial mats in ice-covered Lake Hoare, Antarctica, from noon, at a photon flux of 20 {\textmu}mol m-2 s-1, through to midnight (< 2 {\textmu}mol photons m-2 s-1). Daily average oxygen flux was 200 {\textmu}mol m-2 h-1; and, whereas it was maximal at noon, when a 10 mm broad concentration peak was observed 5 mm below the mat surface, flux correlated only weakly with irradiance. In contrast, relative electron transfer rate, estimated from variable chlorophyll fluorescence, suggested a linear relationship between photosystem activity and irradiance. This contradiction arose because of the conjunction of photosynthetic production of oxygen deep into these transparent, gelatinous mats (diel oxygen change was observed to 17 mm depth) and oxygen diffusion rates too slow to allow equilibration of oxygen concentration profiles with instantaneous production and consumption of oxygen. To confirm this, we developed a mathematical simulation of oxygen dynamics that included diffusion, photosynthesis, and respiration. The simulation further indicated that (1) net oxygen evolution is light limited is and confined to the upper few millimeters of the mat, (2) below 5{\textendash}7 mm, respiration balanced photosynthesis, (3) below 17 mm, respiration and photosynthesis approached zero, even though organic carbon and dissolved oxygen were present, and (4) photosynthesis deep into the mat was dependent on high light transmission through the gelatinous matrix. These conclusions are consistent with current understanding of mat growth dynamics and point to approaches for long-term analysis of microbial mat productivity.}, keywords = {LTER-MCM}, doi = {10.4319/lo.2014.59.3.0674}, author = {Ian Hawes and H. Giles and Peter T. Doran} } @article {3207, title = {Forum: Climate Change and Environmental History}, journal = {Environmental History}, volume = {19}, year = {2014}, month = {04/2014}, pages = {281 - 364}, abstract = {

This Forum explores global climate change, one of this century\&$\#$39;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.

}, keywords = {LTER-MCM}, issn = {1084-5453}, doi = {10.1093/envhis/emu004}, url = {http://envhis.oxfordjournals.org/cgi/doi/10.1093/envhis/emu004}, author = {Carey, M. and Garone, P. and Howkins, Adrian and Endfield, G. H. and Culver, L. and White, S. and Johnson, S. and Fleming, J. R. and Garone, P.} } @article {3533, title = {Global-scale patterns of assemblage structure of soil nematodes in relation to climate and ecosystem properties}, journal = {Global Ecology and Biogeography}, volume = {23}, year = {2014}, month = {01/2014}, pages = {968 - 978}, keywords = {LTER-MCM}, doi = {10.1111/geb.2014.23.issue-910.1111/geb.12177}, url = {http://doi.wiley.com/10.1111/geb.12177}, author = {Uffe N. Nielsen and Edward Ayres and Diana H. Wall and Li, Grace and Richard D. Bardgett and Wu, Tiehang and James R. Garey} } @article {3202, title = {The McMurdo Dry Valleys: A landscape on the threshold of change}, journal = {Geomorphology}, volume = {225}, year = {2014}, month = {11/2014}, pages = {25 - 35}, abstract = {

Field observations of coastal and lowland regions in the McMurdo Dry Valleys suggest they are on the threshold of rapid topographic change, in contrast to the high elevation upland landscape that represents some of the lowest rates of surface change on Earth. A number of landscapes have undergone dramatic and unprecedented landscape changes over the past decade including, the Wright Lower Glacier (Wright Valley) \— ablated several tens of meters, the Garwood River (Garwood Valley) has incised \>\ 3\ m into massive ice permafrost, smaller streams in Taylor Valley (Crescent, Lawson, and Lost Seal Streams) have experienced extensive down-cutting and/or bank undercutting, and Canada Glacier (Taylor Valley) has formed sheer, \>\ 4\ meter deep canyons. The commonality between all these landscape changes appears to be sediment on ice acting as a catalyst for melting, including ice-cement permafrost thaw. We attribute these changes to increasing solar radiation over the past decade despite no significant trend in summer air temperature. To infer possible future landscape changes in the McMurdo Dry Valleys, due to anticipated climate warming, we map \‘at risk\’ landscapes defined as those with buried massive ice in relative warm regions of the valleys. Results show that large regions of the valley bottoms are \‘at risk\’. Changes in surface topography will trigger important responses in hydrology, geochemistry, and biological community structure and function.

}, keywords = {LTER-MCM}, issn = {0169555X}, doi = {10.1016/j.geomorph.2014.03.044}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0169555X14001780http://api.elsevier.com/content/article/PII:S0169555X14001780?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0169555X14001780?httpAccept=text/plain}, author = {Andrew G Fountain and Joseph S. Levy and Michael N. Gooseff and David J. Van Horn} } @article {1064, title = {Soil microbial responses to increased moisture and organic resources along a salinity gradient in a polar desert.}, journal = {Applied and Environmental Microbiology.}, volume = {80}, year = {2014}, month = {05/2014}, pages = {3034-3043}, chapter = {3034}, abstract = {Microbial communities in extreme environments often have low diversity and specialized physiologies suggesting a limited resistance to change. The McMurdo Dry Valleys (MDV) are a microbially dominated, extreme ecosystem currently undergoing climate change-induced disturbances, including the melting of massive buried ice, cutting through of permafrost by streams, and warming events. These processes are increasing moisture across the landscape, altering conditions for soil communities by mobilizing nutrients and salts and stimulating autotrophic carbon inputs to soils. The goal of this study was to determine the effects of resource addition (water/organic matter) on the composition and function of microbial communities in the MDV along a natural salinity gradient representing an additional gradient of stress in an already extreme environment. Soil respiration and the activity of carbon-acquiring extracellular enzymes increased significantly (P < 0.05) with the addition of resources at the low- and moderate-salinity sites but not the high-salinity site. The bacterial community composition was altered, with an increase in Proteobacteria and Firmicutes with water and organic matter additions at the low- and moderate-salinity sites and a near dominance of Firmicutes at the high-salinity site. Principal coordinate analyses of all samples using a phylogenetically informed distance matrix (UniFrac) demonstrated discrete clustering among sites (analysis of similarity [ANOSIM], P < 0.05 and R > 0.40) and among most treatments within sites. The results from this experimental work suggest that microbial communities in this environment will undergo rapid change in response to the altered resources resulting from climate change impacts occurring in this region.}, keywords = {LTER-MCM}, doi = {10.1128/AEM.03414-13}, author = {David J. Van Horn and Okie, J.G. and Heather N. Buelow and Michael N. Gooseff and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {3219, title = {The spatial structure of Antarctic biodiversity}, journal = {Ecological Monographs}, volume = {84}, year = {2014}, month = {05/2014}, pages = {203 - 244}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0012-9615}, doi = {10.1890/12-2216.1}, url = {http://www.esajournals.org/doi/abs/10.1890/12-2216.1}, author = {Peter Convey and Steven L. Chown and Clarke, Andrew and Barnes, David K. A. and Bokhorst, Stef and Vonda Cummings and Hugh W. Ducklow and Francesco Frati and Green, T. G. Allan and Shulamit Gordon and Griffiths, Huw J. and Clive Howard-Williams and Huiskes, Ad H. L. and Johanna Laybourn-Parry and W. Berry Lyons and McMinn, Andrew and Morley, Simon A. and Lloyd S. Peck and Quesada, Antonio and Robinson, Sharon A. and Schiaparelli, Stefano and Diana H. Wall} } @article {3217, title = {Antarctic Thresholds - Ecosystem Resilience and Adaptation (AnT-ERA), a new SCAR-biology programme}, journal = {Polarforschung}, volume = {82}, year = {2013}, month = {10/2013}, pages = {147-150.}, chapter = {147}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://epic.awi.de/34238/1/Polarforschung_82-2_147-150.pdf}, author = {Gutt, J. and Byron Adams and T Bracegirdle and Cowan, D. and Vonda Cummings and di Prisco, G. and Gradinger, R. and Isla, E. and McIntyre, T. and Murphy, E and Lloyd S. Peck and I.R. Schloss and Smith, C. and Suckling, C. C. and Takahashi, A. and Diana H. Wall and J.C. Xavier} } @mastersthesis {4172, title = {Are the Dry Valleys getting wetter? A preliminary assessment of wetness across the McMurdo Dry Valleys landscape}, volume = {M.S.}, year = {2013}, month = {2013}, school = {Pennsylvania State University}, type = {masters}, abstract = {

Liquid water is scarce across the landscape of the McMurdo Dry Valleys (MDV), Antarctica and is associated with soils that are adjacent to streams and lakes, during the annual thaw season. However, seeps, water tracks, and wet patches have been observed at several other locations as well. The source of water for these is likely generated by a combination of infiltration from melting snowpacks, melting of pore ice at the ice table beneath the water tracks, and melting of buried segregation ice formed during winter freezing. We are using high resolution (\<1m pixel) remote sensing data gathered several times per week in the MDV region to determine the spatial and temporal distribution of wet soils. We assess the spatial consistency with which these wet soils occur for the 2008-2009 to 2011-2012 austral summers with complete coverage and partial coverage for 2003-2004 and 2006-2007 austral summers using a land cover classification. We also quantify the soil moisture of wetted soils using an artificial neural network (ANN). The ANN utilizes field radiometer data to retrieve estimates of surface moisture based on the spectral measurements and soil moisture samples collected during the 2010-2011 field season. The remote sensing based analyses of the wetted soils have shown the magnitude to vary greatly and how topography and regional microclimates influence the wetted soils in the MDV. The 2010-2011 austral summer provided the most wetted soil area, 10.21 km2, and 2008- 2009 covered the least, 5.38 km2. The ANN soil moisture distribution in the MDV shows values ranging from 0.36 \% to over 19 \%. We suggest that wet soils are a significant component of this cold desert land system and ecosystem.

}, keywords = {LTER-MCM}, url = {https://etda.libraries.psu.edu/catalog/17364}, author = {Langford, Z. L. and Michael N. Gooseff} } @article {1077, title = {Characterization of fulvic acid fractions of dissolved organic matter during ice-out in a hyper-eutrophic, coastal pond in Antarctica}, journal = {Environmental Research Letters}, volume = {8}, year = {2013}, month = {12/2013}, pages = {045015}, abstract = {Dissolved 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{\textendash}vis and fluorescence spectroscopy, and 13C NMR spectroscopy) of the three fulvic acid fractions helped to explain their behavior during isolation.}, keywords = {LTER-MCM}, doi = {10.1088/1748-9326/8/4/045015}, author = {Kaelin M. Cawley and Diane M. McKnight and Penney L. Miller and Rose M. Cory and Fimmen, Ryan L and Guerard, Jennifer and Markus Dieser and Chris Jaros and Yu-Ping Chin and Christine M. Foreman} } @article {1084, title = {Environmental controls over bacterial communities in polar desert soils}, journal = {Ecosphere}, volume = {4}, year = {2013}, month = {10/2013}, pages = {art127}, keywords = {LTER-MCM}, doi = {10.1890/ES13-00048.1}, author = {Kevin M. Geyer and Adam E. Altrichter and David J. Van Horn and Cristina D. Takacs-Vesbach and Michael N. Gooseff and John E. Barrett} } @article {1092, title = {Factors Controlling Soil Microbial Biomass and Bacterial Diversity and Community Composition in a Cold Desert Ecosystem: Role of Geographic Scale}, journal = {PLoS ONE}, volume = {8}, year = {2013}, month = {06/2013}, pages = {e66103}, keywords = {LTER-MCM}, doi = {10.1371/journal.pone.0066103.s003}, url = {http://www.plosone.org/article/info\%3Adoi\%2F10.1371\%2Fjournal.pone.0066103}, author = {David J. Van Horn and Van Horn, M. Lee and John E. Barrett and Michael N. Gooseff and Adam E. Altrichter and Kevin M. Geyer and Lydia H. Zeglin and Cristina D. Takacs-Vesbach} } @article {1087, title = {The influence of stream thermal regimes and preferential flow paths on hyporheic exchange in a glacial meltwater stream}, journal = {Water Resources Research}, volume = {49}, year = {2013}, month = {09/2013}, pages = {5552 - 5569}, keywords = {LTER-MCM}, doi = {10.1002/wrcr.20410}, url = {http://onlinelibrary.wiley.com/doi/10.1002/wrcr.20410/pdf}, author = {Cozzetto, K and Kenneth E. Bencala and Michael N. Gooseff and Diane M. McKnight} } @article {1081, title = {Physicochemical and biological dynamics in a coastal Antarctic lake as it transitions from frozen to open water}, journal = {Antarctic Science}, volume = {25}, year = {2013}, month = {12/2013}, pages = {663{\textendash}675}, keywords = {LTER-MCM}, author = {Markus Dieser and Christine M. Foreman and Chris Jaros and John T. Lisle and Mark C. Greenwood and Johanna Laybourn-Parry and Penney L. Miller and Yu-Ping Chin and Diane M. McKnight} } @article {1089, title = {Seasonal controls on snow distribution and aerial ablation at the snow-patch and landscape scales, McMurdo Dry Valleys, Antarctica}, journal = {The Cryosphere}, volume = {7}, year = {2013}, month = {09/2013}, pages = {917 - 931}, keywords = {LTER-MCM}, doi = {10.5194/tc-7-917-2013}, url = {http://www.the-cryosphere.net/7/917/2013/tc-7-917-2013.html}, author = {Eveland, Jeffery and Michael N. Gooseff and Lampkin, Derrick J. and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {1096, title = {Shallow groundwater systems in a polar desert, McMurdo Dry Valleys}, journal = {Hydrogeology Journal}, volume = {21}, year = {2013}, month = {02/2013}, pages = {171 - 183}, keywords = {LTER-MCM}, doi = {10.1007/s10040-012-0926-3}, url = {http://link.springer.com/article/10.1007\%2Fs10040-012-0926-3}, author = {Michael N. Gooseff and John E. Barrett and Joseph S. Levy} } @article {1090, title = {Spatial and temporal patterns of snow accumulation and aerial ablation across the McMurdo Dry Valleys, Antarctica}, journal = {Hydrological Processes}, volume = {27}, year = {2013}, month = {09/2013}, pages = {2864 - 2875}, keywords = {LTER-MCM}, doi = {10.1002/hyp.9407}, url = {http://onlinelibrary.wiley.com/doi/10.1002/hyp.9407/pdf}, author = {Eveland, Jeffery and Michael N. Gooseff and Lampkin, Derrick J. and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {1100, title = {Water track modification of soil ecosystems in the Lake Hoare basin, Taylor Valley, Antarctica}, journal = {Antarctic Science}, year = {2013}, pages = {1 - 10}, keywords = {LTER-MCM}, doi = {10.1017/S095410201300045X}, author = {Joseph S. Levy and Andrew G Fountain and Michael N. Gooseff and John E. Barrett and Robert Vantreese and Kathleen A. Welch and W. Berry Lyons and Uffe N. Nielsen and Diana H. Wall} } @article {1101, title = {Aeolian flux of biotic and abiotic material in Taylor Valley, Antarctica}, journal = {Geomorphology}, volume = {155-156}, year = {2012}, month = {6/2012}, pages = {102 - 111}, keywords = {LTER-MCM}, doi = {10.1016/j.geomorph.2011.12.009}, url = {http://www.sciencedirect.com/science/article/pii/S0169555X11006222}, author = {Marie {\v S}aback{\'a} and John C. Priscu and Hassan J. Basagic and Andrew G Fountain and Diana H. Wall and Ross A. Virginia and Mark C. Greenwood} } @article {1105, title = {Antarctic Tardigrada: a first step in understanding molecular operational taxonomic units (MOTUs) and biogeography of cryptic meiofauna}, journal = {Invertebrate Systematics}, volume = {26}, year = {2012}, month = {12/2012}, pages = {526}, keywords = {LTER-MCM}, doi = {10.1071/IS12034}, author = {Czechowski, Paul and Sands, Chester J. and Byron Adams and D{\textquoteright}Haese, Cyrille A. and John A. E. Gibson and McInnes, Sandra J. and Stevens, Mark I.} } @article {1115, title = {Bacteria and diatom co-occurrence patterns in microbial mats from polar desert streams}, journal = {Environmental Microbiology}, year = {2012}, month = {10/2012}, keywords = {LTER-MCM}, doi = {10.1111/j.1462-2920.2012.02872.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1462-2920.2012.02872.x/abstract}, author = {Lee F. Stanish and Sean P. O{\textquoteright}Neill and Antonio Gonz{\'a}lez and Teresa M. Legg and Joseph Knelman and Diane M. McKnight and Sarah A. Spaulding and Diana R. Nemergut} } @article {3535, title = {Challenges to the Future Conservation of the Antarctic}, journal = {Science}, volume = {337}, year = {2012}, month = {Jan-07-2013}, pages = {158 - 159}, abstract = {

The Antarctic Treaty System, acknowledged as a successful model of cooperative regulation of one of the globe\&$\#$39;s largest commons (1), is under substantial pressure. Concerns have been raised about increased stress on Antarctic systems from global environmental change and growing interest in the region\&$\#$39;s resources (2,\ 3). 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 (2,\ 3). 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.

}, keywords = {LTER-MCM}, issn = {0036-8075}, doi = {10.1126/science.1222821}, url = {http://www.sciencemag.org/cgi/doi/10.1126/science.1222821}, author = {Steven L. Chown and Lee, J. E. and Hughes, K. A. and Barnes, J. and Barrett, P.J. and D.M. Bergstrom and Convey, P. and Cowan, Don A. and Crosbie, K. and Dyer, G. and Frenot, Y. and Grant, S. M. and Herr, D. and Kennicutt, M. C. and Lamers, M. and Murray, A. and Possingham, H. P. and Reid, K. and Riddle, M. J. and Ryan, P. G. and Sanson, L. and Shaw, J. D. and Sparrow, M.D. and Summerhayes, C. and Terauds, A. and Diana H. Wall} } @article {1108, title = {Cross-biome metagenomic analyses of soil microbial communities and their functional attributes}, journal = {Proceedings Bational Academy of Sciences}, year = {2012}, month = {11/2012}, keywords = {LTER-MCM}, doi = {10.1073/pnas.1215210110}, url = {www.pnas.org/cgi/doi/10.1073/pnas.1215210110}, author = {Noah Fierer and Jonathan W. Leff and Byron Adams and Uffe N. Nielsen and Scott T. Bates and Christian L. Lauber and Sarah Owens and Jack A. Gilbert and Diana H. Wall and J. Gregory Caporaso} } @article {1122, title = {The ecology of pulse events: insights from an extreme climatic event in a polar desert ecosystem}, journal = {Ecosphere}, volume = {3}, year = {2012}, month = {02/2012}, pages = {art17}, keywords = {LTER-MCM}, doi = {10.1890/ES11-00325.1}, url = {http://www.esajournals.org/doi/abs/10.1890/ES11-00325.1}, author = {Uffe N. Nielsen and Diana H. Wall and Byron Adams and Ross A. Virginia and Ball, Becky and Michael N. Gooseff and Diane M. McKnight} } @article {1104, title = {The geochemistry of upland ponds, Taylor Valley, Antarctica}, journal = {Antarctic Science}, volume = {24}, year = {2012}, month = {2/2012}, pages = {3 - 14}, keywords = {LTER-MCM}, doi = {10.1017/S0954102011000617}, url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online\&aid=8483351}, author = {W. Berry Lyons and Kathleen A. Welch and Christopher B. Gardner and Chris Jaros and Daryl L. Moorhead and Knoepfle, J and Peter T. Doran} } @mastersthesis {4162, title = {Modeling nitrate concentrations in an Antarctic glacial meltwater stream under fluctuating hydrologic conditions and nitrate inputs}, volume = {M.S.}, year = {2012}, school = {Pennsylvania State University}, type = {masters}, abstract = {

The McMurdo Dry Valleys comprise a unique polar desert ecosystem in Victoria Land, Antarctica. The hydrologic system in the Dry Valleys is often characterized as being simplified compared to temperate watersheds, due to the ability to identify physical boundaries and nutrient sources and sinks. We seek to characterize the evolution of streamflow, solutes, and nutrients along a glacial meltwater stream in the McMurdo Dry Valleys, and to understand the role of different sources and sinks under varying hydrologic conditions. The study presented here includes streamflow routing, solute modeling, and nitrate concentration modeling in Von Guerard stream, a stream with abundant algal coverage in the McMurdo Dry Valleys region of Antarctica. The streamflow model is a solution to the kinematic wave routing problem. Solute modeling addresses advection, dispersion, as well as hyporheic zone inputs, which are controlled by weathering and hyporheic exchange. Lastly, the nitrate model builds on the solute model with the addition of a gross primary production (GPP) component. Results indicate that the hyporheic source of nitrate is controlling due to rapid exchange with the main channel. GPP impacts are small due to light-saturated conditions for a majority of the season, but provide a consistent sink for nitrate. The role of advective and dispersive transport is highly dependent on flow conditions, with advective transport controlling at high flows and dispersive controlling at low flows.

}, keywords = {LTER-MCM, hydrology, hyporheic zone, nitrate, nutrients, primary productivity, stream}, url = {https://etda.libraries.psu.edu/catalog/15316}, author = {Bernzott, Emily D. and Michael N. Gooseff} } @book {1123, title = {Poisson Reconstruction of Extreme Submersed Environments: The ENDURANCE Exploration of an Under-Ice Antarctic Lake}, series = {Advances in Visual Computing. ISVC 2012. Lecture Notes in Computer Science.}, volume = {7431}, year = {2012}, pages = {394 - 403}, publisher = {Springer Berlin Heidelberg}, organization = {Springer Berlin Heidelberg}, address = {Berlin, Heidelberg}, abstract = {

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.

}, keywords = {LTER-MCM}, isbn = {978-3-642-33179-4}, doi = {10.1007/978-3-642-33179-4_38}, url = {http://www.springerlink.com/content/hg97w43588229087/}, author = {Alessandro Febretti and Kristof Richmond and Gulati, Shilpa and Flesher, Christopher and Hogan, Bartholomew P. and Andrew Johnson and Stone, William C. and John C. Priscu and Peter T. Doran}, editor = {Bebis, George and Boyle, Richard and Parvin, Bahram and Koracin, Darko and Fowlkes, Charless and Wang, Sen and Choi, Min-Hyung and Mantler, Stephan and Schulze, J{\"u}rgen and Acevedo, Daniel and Mueller, Klaus and Papka, Michael} } @mastersthesis {4171, title = {Snow dynamics in a polar desert, McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2012}, month = {2012}, school = {Pennsylvania State University}, type = {masters}, abstract = {

Snow in the McMurdo Dry Valleys is rare source of moisture for subnivian soils (beneath snow) in a cold desert ecosystem. While sublimation dominates the ablation process, measurable increases in soil moisture are expected to provide more favorable conditions for subnivian soil communities. In addition, snow cover insulates the underlying soil from temperature extremes. Quantifying the spatial distribution and ablation patterns of seasonal snow is necessary to understand these dynamics. Annual snowfall varies spatially ranging from 3 to 50 mm of snow water equivalent, with greater amounts occurring at the coast. Despite receiving very little precipitation, significant amounts of snow can accumulate (via aeolian redistribution) in topographic lees at the valley bottoms, forming thousands of discontinuous patches (typically 1-100 m2 in area). These patches have the potential to act as fertility islands, controlling the landscape distribution of microbial communities, and biogeochemical cycling.

High resolution imagery acquired during the 2009-2010 and 2010-2011 austral summers was used to quantify the distribution of snow across Taylor and Wright Valleys. An object-based classification was used to extract snow-covered area from the imagery. Coupled with topographic parameters, unique distribution patterns were characterized for 5 regions within the neighboring valleys. Time lapses of snow distribution during each season in each region provide insight into spatially characterizing the aerial ablation rates (change in area of landscape covered by snow) across the valleys. The distribution of snow-covered area during the 2009-2010 austral summer is used as a baseline for seasonal comparison. The surrounding regions of Lake Fryxell, Lake Hoare, Lake Bonney, Lake Brownworth, and Lake Vanda exhibited losses of snow-covered area of 9.61 km2 (-93\%), 1.63 km2 (-72\%), 1.07 km2 (-97\%), 2.60 km2 (-82\%), and 0.25 km2 (- 96\%) respectively, as measured from peak accumulation in October to mid-January during the\ 2009-2010 season. Differences in aerial ablation rates within and across local regions suggest that both topographic variation and regional microclimates influence the ablation of seasonal snow cover. Elevation has shown to be the strongest control over aerial ablation. Fifteen 1 km2 plots (3 in each region) were selected to assess the prevalence of snow cover at smaller scales. Results confirm that snow patches form in the same locations each year with some minor deviations observed. Stable isotopes from snow patches also provide insights into temporal and spatial processes associated with ablation. At the snow patch scale, neighboring patches often exhibit considerable differences in aerial ablation rates, presumably controlled by snow depth. This highlights the importance of both the landscape and snow patch scales in assessing the effects of snow cover on biogeochemical cycling and microbial communities.

}, keywords = {LTER-MCM}, url = {https://etda.libraries.psu.edu/catalog/12680}, author = {Eveland, Jeffery and Michael N. Gooseff} } @article {1128, title = {Bacterial Community Structure Along Moisture Gradients in the Parafluvial Sediments of Two Ephemeral Desert Streams}, journal = {Microbial Ecology}, volume = {61}, year = {2011}, month = {4/2011}, pages = {543 - 556}, keywords = {LTER-MCM}, doi = {10.1007/s00248-010-9782-7}, url = {http://www.springerlink.com/content/r83j53334v5n505w/}, author = {Lydia H. Zeglin and Clifford N. Dahm and John E. Barrett and Michael N. Gooseff and Shannon K. Fitpatrick and Cristina D. Takacs-Vesbach} } @book {1142, title = {Frontiers in Understanding Climate Change and Polar Ecosystems}, series = {Committee on Frontiers in Understanding Climate Change and Polar Ecosystems Polar Research Board Division of Earth and Life Studies}, year = {2011}, publisher = {The National Academies Press}, organization = {The National Academies Press}, keywords = {LTER-MCM}, isbn = {0-309-21087-9}, author = {Grebmeier, J. and John C. Priscu} } @mastersthesis {4163, title = {Hydrologic controls of nutrient fluxes in glacial meltwater streams at inter-annual, seasonal, and daily timescales in the McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2011}, school = {Pennsylvania State University}, type = {masters}, abstract = {

In the McMurdo Dry Valleys of Antarctica, glaciers are hydrologically linked to closed-basin lakes at the valley floor by glacial meltwater streams. Streams flow through porous, well-defined channels with extensive chemically active hyporheic zones. Temporally varying dynamics of meltwater generation and sub-stream thaw depth are thought to control the potential for the hyporheic zone and benthic communities to influence transport of nutrients and dissolved ions downstream. Using the McMurdo LTER database, patterns in stream discharge, electrical conductivity (both with 15-minute sampling intervals), and solute chemistry (weekly sampling intervals) were examined on eight MDV streams from 1990-2008. Discharge and electrical conductivity values were highly variable among streams. Discharge values were highly dependent upon glacial source area, but meteorological and topographical complexities create large variability at all time scales. The longer streams were found to have much higher electrical conductivity values than the shorter streams, suggesting that there are more opportunities for hyporheic weathering reactions along longer stream reaches. Weekly sampled water solutes from each stream\&$\#$39;s entire record were plotted against the discharge recorded at the time when the sample was taken. Silicate concentrations displayed a decreasing logarithmic relationship, while nutrient concentrations had no apparent relationship. This suggests that with the exception to bioreactive solutes, the majority of hyporheic interactions could possibly be characterized by electrical conductivity and discharge. To attain information on in-stream nutrient dynamics and nutrient fluxes, glacial source water at the upper reach of Green Creek and stream outlet water at the lower reach of Green Creek were sampled hourly for two separate diel periods during the 2008-09 austral summer. Both dates were in late January under two distinct flow conditions (~0.5 L/s and ~10 L/s). Under low flow conditions, nutrient cycling was found to be uptake dominated. High flow conditions showed both uptake and regeneration with much higher nutrient loads, but as in the low flow conditions, no apparent temporal trends were found. Nutrient concentrations could not be predicted using the two parameters of discharge and electrical conductivity with in-stream nutrient dynamics likely too complicated at the sub-daily scale.

}, keywords = {LTER-MCM, Antarctica, biogeochemistry, chemical weathering, discharge, electrical conductivity, glacial melt, glaciers, hydrology, hyporheic, MCM LTER, McMurdo Dry Valleys, nutrient fluxes, nutrients, polar desert, solute chemistry, stream chemistry, streamflow, water chemistry}, url = {https://etda.libraries.psu.edu/catalog/11568}, author = {Weaver, Mitchell R. and Michael N. Gooseff} } @article {1135, title = {Hydrological Connectivity of the Landscape of the McMurdo Dry Valleys, Antarctica}, journal = {Geography Compass}, volume = {5}, year = {2011}, month = {09/2011}, pages = {666 - 681}, keywords = {LTER-MCM}, doi = {10.1111/j.1749-8198.2011.00445.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1749-8198.2011.00445.x}, author = {Michael N. Gooseff and Diane M. McKnight and Peter T. Doran and Andrew G Fountain and W. Berry Lyons} } @article {3537, title = {Implications of meltwater pulse events for soil biology and biogeochemical cycling in a polar desert}, journal = {Polar Research}, volume = {3081281030352511340}, year = {2011}, month = {12/2011}, keywords = {LTER-MCM}, issn = {0800-0395}, doi = {10.3402/polar.v30i0.14555}, url = {http://www.polarresearch.net/index.php/polar/article/view/14555}, author = {Ball, Becky and John E. Barrett and Michael N. Gooseff and Ross A. Virginia and Diana H. Wall} } @article {1134, title = {Molecular study of worldwide distribution and diversity of soil animals}, journal = {Proceedings of the National Academy of Sciences}, volume = {108}, year = {2011}, month = {10/2011}, pages = {17720 - 17725}, keywords = {LTER-MCM}, doi = {10.1073/pnas.1103824108}, author = {Tiehang Wu and Edward Ayres and Richard D. Bardgett and Diana H. Wall and James R. Garey} } @article {1133, title = {Water tracks and permafrost in Taylor Valley, Antarctica: Extensive and shallow groundwater connectivity in a cold desert ecosystem}, journal = {Geological Society of America Bulletin}, volume = {123}, year = {2011}, month = {11/2011}, pages = {2295-2311}, keywords = {LTER-MCM}, doi = {10.1130/B30436.1}, url = {http://bulletin.geoscienceworld.org/content/123/11-12/2295.short}, author = {Joseph S. Levy and Andrew G Fountain and Michael N. Gooseff and Kathleen A. Welch and W. Berry Lyons} } @article {1138, title = {When a habitat freezes solid: microorganisms over-winter within the ice column of a coastal Antarctic lake}, journal = {FEMS Microbiology Ecology}, volume = {76}, year = {2011}, month = {06/2011}, pages = {401 - 412}, keywords = {LTER-MCM}, doi = {10.1111/j.1574-6941.2011.01061.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2011.01061.x/full}, author = {Christine M. Foreman and Markus Dieser and Mark Greenwood and Rose M. Cory and Johanna Laybourn-Parry and John T. Lisle and Chris Jaros and Penney L. Miller and Yu-Ping Chin and Diane M. McKnight} } @inbook {1168, title = {Antarctic McMurdo Dry Valley stream ecosystems as analog to fluvial systems on Mars}, booktitle = {Life in Antarctic Deserts and other Cold Dry Environments}, year = {2010}, pages = {139 - 159}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge}, keywords = {LTER-MCM}, isbn = {9780521889193}, doi = {10.1017/CBO9780511712258.005}, author = {Michael N. Gooseff and Diane M. McKnight and Carr, M. H. and Baeseman, J.}, editor = {Peter T. Doran and W. Berry Lyons and Diane M. McKnight} } @article {1157, title = {Design and deployment of a four-degrees-of-freedom hovering autonomous underwater vehicle for sub-ice exploration and mapping}, journal = {Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment}, volume = {224}, year = {2010}, month = {11/2010}, pages = {341 - 361}, keywords = {LTER-MCM}, doi = {10.1243/14750902JEME214}, author = {Stone, W and Bartholomew P Hogan and Flesher, C and Gulati, S and Kristof Richmond and Murarka, A and Kuhlman, G and Idharan, M and Siegel, V and Price, R M and Peter T. Doran and John C. Priscu} } @article {1161, title = {Effect of instrument-specific response on the analysis of fulvic acid fluorescence spectra}, journal = {Limnology and Oceanography: Methods}, volume = {8}, year = {2010}, month = {07/2010}, pages = {67-78}, keywords = {LTER-MCM}, url = {http://www.aslo.org/lomethods/free/2010/0067.html}, author = {Rose M. Cory and Mathew P. Miller and Diane M. McKnight and Guerard, Jennifer and Penney L. Miller} } @inbook {1171, title = {Factors promoting microbial diversity in the McMurdo Dry Valleys}, booktitle = {Life in Antarctic Deserts and other Cold Dry Environments: Astrobiological Analogues}, series = {Cambridge Astrobiology}, volume = {5}, year = {2010}, pages = {221-257}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, keywords = {LTER-MCM}, isbn = {9780521889193}, doi = {10.1017/CBO9780511712258.008}, url = {http://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511712258\&cid=CBO9780511712258A015}, author = {Cristina D. Takacs-Vesbach and Lydia H. Zeglin and Michael N. Gooseff and John E. Barrett and John C. Priscu} } @inbook {1172, title = {The legacy of aqueous environments on soils of the McMurdo Dry Valleys: contexts for future exploration of martian soils}, booktitle = {Life in Antarctic Deserts and other Cold Dry Environments}, volume = {5}, year = {2010}, pages = {78 - 109}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge}, keywords = {LTER-MCM}, isbn = {9780521889193}, doi = {10.1017/CBO9780511712258.003}, url = {http://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511712258\&cid=CBO9780511712258A010}, author = {John E. Barrett and Poage, M and Michael N. Gooseff and Cristina D. Takacs-Vesbach} } @book {1173, title = {Life in Antarctic Deserts and Other Cold Environments}, series = {Astrobiological Analogs}, volume = {5}, year = {2010}, pages = {307}, publisher = {Cambridge University Press.}, organization = {Cambridge University Press.}, address = {Cambridge}, keywords = {LTER-MCM, Planetary Science}, isbn = {9780511712258}, doi = {10.1017/CBO9780511712258}, url = {http://ebooks.cambridge.org/ebook.jsf?bid=CBO9780511712258}, author = {Peter T. Doran and W. Berry Lyons and Diane M. McKnight}, editor = {Diane M. McKnight and Michael N. Gooseff and Cristina D. Takacs-Vesbach and Jill A. Mikucki and Martyn Tranter and Sun, Henry J} } @article {1174, title = {Physiochemical properties influencing biomass abundance and primary production in Lake Hoare, Antarctica}, journal = {Ecological Modelling}, year = {2010}, keywords = {LTER-MCM}, doi = {LTER}, author = {Herbei, Radu and W. Berry Lyons and Johanna Laybourn-Parry and Christopher B. Gardner and John C. Priscu and Diane M. McKnight} } @article {1154, title = {Spatial variations in the geochemistry of glacial meltwater streams in the Taylor Valley, Antarctica}, journal = {Antarctic Science}, volume = {22}, year = {2010}, month = {12/2010}, pages = {662 - 672}, keywords = {LTER-MCM}, doi = {10.1017/S0954102010000702}, url = {http://www.montana.edu/lkbonney/DOCS/Publications/WelchEtAl2010Geochemistry.pdf}, author = {Kathleen A. Welch and W. Berry Lyons and Whisner, Carla and Christopher B. Gardner and Michael N. Gooseff and Diane M. McKnight and John C. Priscu} } @conference {1164, title = {Toward autonomous scientific exploration of ice-covered lakes{\textemdash}Field experiments with the ENDURANCE AUV in an Antarctic Dry Valley}, booktitle = {2010 IEEE International Conference on Robotics and Automation (ICRA 2010)2010 IEEE International Conference on Robotics and Automation}, year = {2010}, month = {05/2010}, pages = {308 - 315}, publisher = {IEEE}, organization = {IEEE}, address = {Anchorage, AK}, keywords = {LTER-MCM}, isbn = {978-1-4244-5038-1}, doi = {10.1109/ROBOT.2010.5509224}, author = {Gulati, S and Kristof Richmond and Flesher, C and Bartholomew P Hogan and Murarka, A and Gregory Kuhlmann and Mohan Sridharan and Stone, W and Peter T. Doran} } @article {1186, title = {Hydrologic characteristics of lake- and stream-side riparian wetted margins in the McMurdo Dry Valleys, Antarctica}, journal = {Hydrological Processes}, volume = {23}, year = {2009}, pages = {1255-1267}, keywords = {LTER-MCM}, doi = {LTER}, author = {Northcott, M and Michael N. Gooseff and John E. Barrett and Lydia H. Zeglin and Cristina D. Takacs-Vesbach and Humphrey, J} } @article {1189, title = {Landscape Distribution of Microbial Activity in the McMurdo Dry Valleys: Linked Biotic Processes, Hydrology, and Geochemistry in a Cold Desert Ecosystem}, journal = {Ecosystems}, volume = {12}, year = {2009}, pages = {562-573}, keywords = {LTER-MCM}, doi = {LTER}, author = {Lydia H. Zeglin and Sinsabaugh, R and John E. Barrett and Michael N. Gooseff and Cristina D. Takacs-Vesbach} } @article {1200, title = {Molecular profiling of soil animal diversity in natural ecosystems: incongruence of molecular and morphological results}, journal = {Soil Biology and Biochemistry}, year = {2009}, pages = {849-857}, keywords = {LTER-MCM}, doi = {10.1016/j.soilbio.2009.02.003}, author = {Wu, T and Edward Ayres and Li, G and Richard D. Bardgett and Diana H. Wall and James R. Garey} } @article {1191, title = {Particulate organic and dissolved inorganic carbon stable isotopic compositions in Taylor Valley lakes, Antarctica: the effect of legacy}, journal = {Hydrobiologia}, volume = {632}, year = {2009}, pages = {139-156}, keywords = {LTER-MCM}, doi = {LTER}, author = {Knoepfle, J and Peter T. Doran and Kenig, Fabien and W. Berry Lyons and Galchenko, V} } @article {1192, title = {The saline lakes of the McMurdo Dry Valleys, Antarctica,}, journal = {Aquatic Geochemistry}, year = {2009}, pages = {321-348}, keywords = {LTER-MCM}, doi = {LTER}, author = {William J. Green and W. Berry Lyons} } @article {1193, title = {Spatial variation in soil active-layer geochemistry across hydrologic margins in polar desert ecosystems.}, journal = {Hydrology and Earth System Sciences}, volume = {13}, year = {2009}, pages = {2349-2358}, keywords = {LTER-MCM}, doi = {LTER}, author = {John E. Barrett and Michael N. Gooseff and Cristina D. Takacs-Vesbach} } @article {1196, title = {Thermal Characterisation of Active Layer Across a Soil Moisture Gradient in the McMurdo Dry Valleys, Antarctica}, journal = {Permafrost and Periglacial Processes}, volume = {20}, year = {2009}, pages = {27-39}, keywords = {LTER-MCM}, doi = {10.1002/ppp.634}, author = {Ikard, S and Michael N. Gooseff and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {1202, title = {Global decomposition experiment shows soil animal impacts on decomposition are climate dependent}, journal = {Global Change Biology}, volume = {14}, year = {2008}, month = {11/2008}, pages = {2661-2677}, keywords = {LTER-MCM}, doi = {10.1111/j.1365-2486.2008.01672.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2008.01672.x/full}, author = {Diana H. Wall and Mark A. Bradford and Mark G. StJohn and John A. Trofymow and Valerie Behan-Pelletier and David E. Bignell and J. Mark Dangerfield and William J. Parton and Josef Rusek and Winfried Voigt and Volkmar Wolters and Holley Zadeh Gardel and Fred O. Ayuke and Richard Bashford and Olga I. Beljakova and Patrick J. Bohlen and Alain Brauman and Stephen Flemming and Joh R. Henschel and Dan L. Johnson and T. Hefin Jones and Marcela Kovarova and J. Marty Kranabetter and Les Kutny and Kuo-Chuan Lin and Mohamed Maryati and Dominique Masse and Andrei Pokarzhevskii and Homathevi Rahman and Millor G. Sabara and Joerg-Alfred Salamon and Michael J. Swift and Amanda Varela and Heraldo L. Vasconcelos and Don White and Xiaming Zou} } @inbook {1214, title = {High-latitude rivers and streams.}, booktitle = {Polar Lakes and Rivers: Limnology of Arctic and Antarctic Aquatic Ecosystems}, year = {2008}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {Oxford}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diane M. McKnight and Michael N. Gooseff and Warwick F. Vincent and Peterson, B}, editor = {Warwick F. Vincent and Johanna Laybourn-Parry} } @article {1224, title = {Stoichiometry of soil enzyme activity at global scale.}, journal = {Ecology Letters}, volume = {11}, year = {2008}, pages = {1252-1264}, keywords = {LTER-MCM}, doi = {LTER}, author = {Sinsabaugh, R and Gallo, M and Gartner, T and Hobbie, S and Holland, K and Keeler, B and Powers, J and Stursova, M and Cristina D. Takacs-Vesbach and Waldrop, M and Wallenstein, M and Lauber, M and Zak, D and Lydia H. Zeglin and Weintraub, M and Ahmed, B and Allison, S and Crenshaw, C and Contosta, A and Cusack, D and Frey, S} } @article {1240, title = {Controls on the spatial dimensions of wetted hydrologic margins of two antarctic lakes}, journal = {Vadose Zone Journal}, volume = {6}, year = {2007}, pages = {841-848}, keywords = {LTER-MCM}, doi = {10.2136/​vzj2006.0161}, author = {Michael N. Gooseff and John E. Barrett and Melissa L. Northcott and D. Brad Bate and Kenneth R. Hill and Lydia H. Zeglin and Bobb, M and Cristina D. Takacs-Vesbach} } @article {1248, title = {The southernmost worm, Scottnema lindsayae (Nematoda): diversity, dispersal and ecological stability.}, journal = {Polar Biology}, volume = {30}, year = {2007}, pages = {809-815}, keywords = {LTER-MCM}, doi = {LTER}, author = {Byron Adams and Diana H. Wall and Gozel, U and Dillman, A and Chaston, J and Hogg, I} } @mastersthesis {1249, title = {Spatial and Temporal Active Layer Thermal Dynamics from Temperature Time Series Analysis: Case Studies from Lake Fryxell, McMurdo Dry Valleys, Antarctica.}, volume = {M.S.}, year = {2007}, school = {Colorado School of Mines}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Ikard, S} } @proceedings {1251, title = {Trends in discharge and flow season timing of the Onyx River, Wright Valley, Antarctica since 1969}, journal = {Antarctica; A keystone in a changing world--online proceedings for the tenth international symposium}, year = {2007}, publisher = {U.S. Geological Survey Open-File Report 2007-1047}, keywords = {LTER-MCM}, doi = {LTER}, author = {Michael N. Gooseff and Diane M. McKnight and Peter T. Doran and W. Berry Lyons}, editor = {Alan Cooper and Carol Raymond and ISAES Editorial Team} } @mastersthesis {1253, title = {WETTED MARGIN HYDROLOGY OF THE DRY VALLEYS OF ANTARCTICA}, volume = {M.S.}, year = {2007}, school = {Colorado School of Mines,}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Northcott, M} } @article {1257, title = {Adaptation and acclimation of photosynthetic microorganisms to permanently cold environments}, journal = {Microbial and Molecular Biology Review}, volume = {70}, year = {2006}, month = {03/2006}, pages = {222-252}, abstract = {

Persistently cold environments constitute one of our world\&$\#$39;s largest ecosystems, and microorganisms dominate the biomass and metabolic activity in these extreme environments. The stress of low temperatures on life is exacerbated in organisms that rely on photoautrophic production of organic carbon and energy sources. Phototrophic organisms must coordinate temperature-independent reactions of light absorption and photochemistry with temperature-dependent processes of electron transport and utilization of energy sources through growth and metabolism. Despite this conundrum, phototrophic microorganisms thrive in all cold ecosystems described and (together with chemoautrophs) provide the base of autotrophic production in low-temperature food webs. Psychrophilic (organisms with a requirement for low growth temperatures) and psychrotolerant (organisms tolerant of low growth temperatures) photoautotrophs rely on low-temperature acclimative and adaptive strategies that have been described for other low-temperature-adapted heterotrophic organisms, such as cold-active proteins and maintenance of membrane fluidity. In addition, photoautrophic organisms possess other strategies to balance the absorption of light and the transduction of light energy to stored chemical energy products (NADPH and ATP) with downstream consumption of photosynthetically derived energy products at low temperatures. Lastly, differential adaptive and acclimative mechanisms exist in phototrophic microorganisms residing in low-temperature environments that are exposed to constant low-light environments versus high-light- and high-UV-exposed phototrophic assemblages.

}, keywords = {LTER-MCM, Biggie}, doi = {10.1128/​MMBR.70.1.222-252.2006}, author = {Rachael M. Morgan-Kiss and John C. Priscu and Pocock, T and Gudynaite-Savitch, L and Norman P.A. Huner} } @article {1256, title = {Antarctic Climate Cooling and Response of Diatoms in Glacial Meltwater Streams}, journal = {Geophysical Research Letters}, volume = {33}, year = {2006}, month = {04/2006}, pages = {L07406}, type = {Journal}, abstract = {

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.

}, keywords = {LTER-MCM, Biggie}, doi = {10.1029/2006GL025903}, author = {Rhea M.M. Esposito and Horn, S and Diane M. McKnight and Cox, M and Grant, M and Sarah A. Spaulding and Peter T. Doran and Cozzetto, K} } @article {1272, title = {Measuring ecosystem response in a rapidly changing environment: the Latitudinal Gradient Project}, journal = {Antarctic Science.}, volume = {10}, year = {2006}, keywords = {LTER-MCM}, doi = {LTER}, author = {Clive Howard-Williams and Peterson, D and W. Berry Lyons and Cattaneo-Vietti, R and Shulamit Gordon} } @article {1258, title = {A stable isotopic investigation of a polar desert hydrologic system, McMurdo Dry Valleys, Antarctica}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {38}, year = {2006}, month = {02/2006}, pages = {60-71}, keywords = {LTER-MCM}, doi = {10.1657/1523-0430(2006)038[0060:ASIIOA]2.0.CO;2}, author = {Michael N. Gooseff and W. Berry Lyons and Diane M. McKnight and Bruce H. Vaughn and Andrew G Fountain and Carolyn Dowling} } @article {1300, title = {Halogen geochemistry of the McMurdo Dry Valleys Lakes, Antarctica: clues to the origin of solutes and lake evolution}, journal = {Geochimica et Cosmochimica Acta}, volume = {69}, year = {2005}, pages = {305-323}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Snyder, G and Olesik, J and Graham, E and G. M. Marion and Robert J. Poreda} } @inbook {1307, title = {Polar Systems}, booktitle = {Millennium Ecosystem Assessment. Current State and Trends: Findings of the Condition and Trends Working Group}, year = {2005}, pages = {717-743}, publisher = {Island Press}, organization = {Island Press}, keywords = {LTER-MCM}, doi = {LTER}, author = {F. S. Chapin and McGuire, A and Nuttall, M and Ross A. Virginia and Young, O and Zimov, S and Christensen, T and Godduhn, A and Murphy, E and Diana H. Wall and Zockler, C and Berman, M and Callaghan, T and Peter Convey and A. S. Crepin and Danell, K and Hugh W. Ducklow and Forbes, B and Kofinas, G}, editor = {R. Hassan and R. Scholes and N. Ash} } @article {1288, title = {Sensitivity analysis of conservative and reactive stream transient storage models applied to field data from multiple-reach experiments}, journal = {Advances in Water Resources}, volume = {28}, year = {2005}, month = {05/2005}, pages = {479-492}, keywords = {LTER-MCM}, doi = {10.1016/j.advwatres.2004.11.012}, author = {Michael N. Gooseff and Kenneth E. Bencala and Durelle T. Scott and Robert L. Runkel and Diane M. McKnight} } @inbook {1322, title = {Antarctic Paleolimnology}, booktitle = {Long-Term Environmental Change in Arctic and Antarctic Lakes}, year = {2004}, publisher = {Kluwer Academic Publishers}, organization = {Kluwer Academic Publishers}, keywords = {LTER-MCM}, author = {Hodgson, D and John A. E. Gibson and Peter T. Doran}, editor = {Pienitz, R and Douglas, Marianne S. V. and J.P. Smol} } @article {1318, title = {Can warming induce advances of polar glaciers, Taylor Valley, Antarctica}, journal = {Journal of Glaciology}, volume = {50}, year = {2004}, month = {12/2004}, pages = {556-564}, keywords = {LTER-MCM}, doi = {10.3189/172756504781829701}, author = {Andrew G Fountain and Thomas A. Neumann and Paul L. Glenn and Trevor Chinn} } @article {1319, title = {Denitrification and hydrologic transient storage in a glacial meltwater stream, McMurdo Dry Valleys, Antarctica}, journal = {Limnology and Oceanography}, volume = {49}, year = {2004}, month = {09/2004}, pages = {1884-1895}, keywords = {LTER-MCM}, doi = {10.4319/lo.2004.49.5.1884}, author = {Michael N. Gooseff and Diane M. McKnight and Robert L. Runkel and John H. Duff} } @article {1341, title = {Reach-scale cation exchange controls on major ion chemistry of an Antarctic glacial meltwater stream}, journal = {Special issue of Aquatic Geochemistry on the McMurdo Dry Valleys}, volume = {10}, year = {2004}, pages = {221-238}, keywords = {LTER-MCM}, author = {Michael N. Gooseff and Diane M. McKnight and Robert L. Runkel} } @inbook {1359, title = {Century to millennial scale climate change and ecosystem response in Taylor Valley, Antarctica}, booktitle = {Climate Variability and Ecosystem Response at Long-Term Ecological Research Sites}, series = {Long-Term Ecological Research Network}, year = {2003}, pages = {319-340}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York City}, keywords = {LTER-MCM, Climate Response}, isbn = {0195150597}, author = {Andrew G Fountain and W. Berry Lyons}, editor = {D. Greenland and D. G. Goodin and R. C. Smith} } @article {1361, title = {Determining long time-scale hyporheic zone flow paths in Antarctic streams}, journal = {Hydrological Processes}, volume = {17}, year = {2003}, pages = {1691-1710}, keywords = {LTER-MCM}, author = {Michael N. Gooseff and Diane M. McKnight and Robert L. Runkel and Bruce H. Vaughn} } @article {1370, title = {Long-term perspectives on biodiversity-ecosystem function.}, journal = {Bioscience}, year = {2003}, pages = {89-98}, keywords = {LTER-MCM}, author = {Symstad, A and Chapin III, F and Diana H. Wall and Gross, K and Huenneke, L and Mittelbach, G and Debra P. C. Peters and Tilman, D} } @mastersthesis {1372, title = {Phosphorus in Taylor Valley, Antarctica: the connection between landscape age and nutrient limitation in aquatic ecosystem components}, volume = {M.S.}, year = {2003}, school = {The Ohio State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Gudding, J} } @article {1368, title = {Strontium isotopic signatures of the streams and lakes of Taylor Valley, southern Victoria Land, Antarctica: chemical weathering in a polar climate}, journal = {Aquatic Geochemistry}, volume = {8}, year = {2003}, pages = {875-895}, keywords = {LTER-MCM}, author = {W. Berry Lyons and C. A. Nezat and Benson, L and Bullen, T and Graham, E and Kidd, J and Kathleen A. Welch and Thomas, J} } @article {1378, title = {Direct observation of aluminosilicate weathering in the hyporheic zone of an Antarctic Dry Valley stream}, journal = {Geochimica et Cosmochimica Acta}, volume = {66}, year = {2002}, pages = {1335-1347}, keywords = {LTER-MCM}, author = {Maurice, P and Diane M. McKnight and Leff, L and Fulghun, J and Michael N. Gooseff} } @article {1376, title = {Snow patch influence on soil biogeochemical processes and invertebrate distribution in the McMurdo Dry Valleys, Antarctica}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {35}, year = {2002}, month = {02/2003}, pages = {91-99}, type = {Journal}, keywords = {LTER-MCM, Biggie}, doi = {10.1657/1523-0430(2003)035[0091:SPIOSB]2.0.CO;2}, url = {http://instaar.metapress.com/content/r086455ju7213711/}, author = {Michael N. Gooseff and John E. Barrett and Peter T. Doran and Andrew G Fountain and W. Berry Lyons and Andrew N. Parsons and Porazinska, D and Ross A. Virginia and Diana H. Wall} } @article {1375, title = {Weathering reactions and hyporheic exchange controls on stream water chemistry in a glacial meltwater stream in the McMurdo Dry Valleys}, journal = {Water Resources Research}, volume = {38}, year = {2002}, month = {12/2002}, pages = {1279-1296}, type = {Journal}, keywords = {LTER-MCM, Biggie}, doi = {10.1029/2001WR000834}, url = {http://www.agu.org/pubs/crossref/2002/2001WR000834.shtml}, author = {Michael N. Gooseff and Diane M. McKnight and W. Berry Lyons and Blum, A} } @phdthesis {1366, title = {Modeling hyporheic exchange influences on biogeochemical processes in dry valley streams, Antarctica}, volume = {Ph.D.}, year = {2001}, school = {University of Colorado}, type = {doctoral}, abstract = {

The ephemeral streams of the Dry Valleys of Antarctica provide habitat to benthic algal mats, and greatly control the quantity and quality of glacial melt water that enters closed basin Dry Valley lakes. Dry Valley watersheds are composed of streambeds and adjacent hyporheic zones. Hydrologic exchange of water and solutes between the stream and the hyporheic zone has the overall effect of increasing residence time in the stream/hyporheic system. Biogeochemical reactions (e.g. chemical weathering, nutrient assimilation) occur both in the water column and in the hyporheic zone. Field experiments and solute transport modeling were employed to elucidate the effects of rapid hyporheic exchange on biogeochemical cycling in Antarctic streams. The results presented here show that (1) large portions of the wetted zone that surrounds each stream is a hyporheic zone, and that stream water exchanges into and out of extended portions of this zone on the order of weeks, (2) the rapid exchange of stream water between the water column and the hyporheic zone controls the rate of weathering in streambed sediments, and (3) denitrification in streams is limited by the conversion of NO2\ to N2O, while the conversion of NO3\ to NO2\ occurs very quickly.

}, keywords = {LTER-MCM}, author = {Michael N. Gooseff} } @inbook {1426, title = {Climate and hydrologic variations and implications for lake and stream ecological response in the McMurdo Dry Valleys, Antarctica}, booktitle = {Climate Variability and Ecosystem Response at Long Term Ecological Research Sites}, year = {2000}, pages = {174-195}, publisher = {Oxford University Press}, organization = {Oxford University Press}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons and Diane M. McKnight and Chris Jaros and Andrew G Fountain and Thomas H. Nylen and Peter T. Doran and Clive Howard-Williams}, editor = {D. Greenland and D. G. Goodin and R. C. Smith} } @article {1427, title = {Distribution and phylogeny of bacterial communities associated with mineral particles in Antarctic lake ice.}, journal = {Microbial Biology}, volume = {39}, year = {2000}, pages = {197-202}, keywords = {LTER-MCM}, author = {Douglas A. Gordon and John C. Priscu and Stephen J. Giovannoni} } @article {1428, title = {Distribution of organic carbon and nitrogen in surface soils in the McMurdo Dry Valleys, Antarctica.}, journal = {Polar Biology}, volume = {23}, year = {2000}, pages = {121-128}, keywords = {LTER-MCM}, author = {Christian H. Fritsen and Grue, A and John C. Priscu} } @article {1431, title = {Global change effects on above and below ground biodiversity in terrestrial ecosystems: interactions and implications for ecosystem functioning}, journal = {Bioscience}, volume = {50}, year = {2000}, pages = {1089-1099}, keywords = {LTER-MCM}, doi = {LTER}, author = {Wolters, V and Wardle, D and Brussaard, L and J. Mark Dangerfield and Brown, V and Giller, K and Hooper, D and Osvaldo E. Sala and Tiedje, J and van Veen, J and Silver, W and Bignell, D and David C. Coleman and Lavelle, P and van der Putten, W and DeRuiter, P and Josef Rusek and Diana H. Wall} } @article {1433, title = {Interactions between above and belowground biodiversity in terrestrial ecosystems: patterns, mechanisms and feedbacks}, journal = {BioScience}, volume = {50}, year = {2000}, pages = {1049-1061}, keywords = {LTER-MCM}, author = {Hooper, D and Lavelle, P and van der Putten, W and DeRuiter, P and Josef Rusek and Silver, W and Tiedje, J and Wolters, V and Bignell, D and Brown, V and Brussaard, L and J. Mark Dangerfield and Diana H. Wall and Wardle, D and David C. Coleman and Giller, K} } @article {1422, title = {Phytoplankton dynamics in a stably stratified Antarctic lake during winter darkness}, journal = {Journal of Phycology}, volume = {36}, year = {2000}, month = {10/2000}, pages = {852-861}, type = {Journal}, keywords = {LTER-MCM, Biggie, winter}, doi = {10.1046/j.1529-8817.2000.00031.x}, author = {Diane M. McKnight and B. L. Howes and C. D. Taylor and D. D. Goehringer} } @inbook {1438, title = {Soil Biodiversity and Ecosystem Functioning}, booktitle = {Biological Resource Management. Connecting Science and Policy}, year = {2000}, pages = {283-290}, publisher = {Springer}, organization = {Springer}, address = {Heidelberg}, keywords = {LTER-MCM}, author = {Diana H. Wall and J.M. Lynch}, editor = {E. Balazs and E. Galante and J.M. Lynch and J.S. Schepers} } @inbook {1471, title = {Soil Biodiversity: life in soil}, booktitle = {The Living Planet in Crisis}, year = {1999}, pages = {124-128}, publisher = {Columbia University Press}, organization = {Columbia University Press}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana H. Wall}, editor = {J. Cracraft and F. Griffo} } @inbook {1488, title = {Cobalt Cycling and Fate in Lake Vanda}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {205-215}, keywords = {LTER-MCM}, author = {William J. Green and Donald E. Canfield and Philip Nixon} } @article {1491, title = {Cyanobacterial communities associated with mineral particles in antarctic lake ice}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {224-225}, keywords = {LTER-MCM}, author = {Douglas A. Gordon and Brian D. Lanoil and Stephen J. Giovannoni and John C. Priscu} } @article {1519, title = {Nitrogen fixation within permanent ice covers on lakes in the McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {218-220}, keywords = {LTER-MCM}, author = {Amanda M. Grue and Christian H. Fritsen and John C. Priscu} } @article {1482, title = {Perennial Antarctic Lake Ice: An Oasis for Life in a Polar Desert}, journal = {Science}, volume = {280}, year = {1998}, month = {06/1998}, pages = {2095-2098}, type = {Journal}, keywords = {LTER-MCM, Biggie}, doi = {10.1126/science.280.5372.2095}, url = {http://www.sciencemag.org/content/280/5372/2095.short}, author = {John C. Priscu and Christian H. Fritsen and Edward E. Adams and Stephen J. Giovannoni and Hans W. Paerl and Christopher P. McKay and Peter T. Doran and Douglas A. Gordon and Brian D. Lanoil and James L. Pinckney} } @inbook {1439, title = {A Temperature area index of stream discharge in Taylor Valley, Antarctica}, booktitle = {Applications of Remote Sensing in Hydrology}, year = {1998}, pages = {29-39}, publisher = {National Water Research Institute , Environment Canada}, organization = {National Water Research Institute , Environment Canada}, keywords = {LTER-MCM}, author = {Gayle L. Dana and Davis, R and Andrew G Fountain and Robert A. Wharton Jr.}, editor = {A. Pietroniro and R. Granger and T.J. Pultz} } @inbook {1544, title = {The abundance of planktonic virus-like particles in Antarctic lakes}, booktitle = {Ecosystem Processes in Antarctic Ice-free Landscapes}, year = {1997}, pages = {241-250}, publisher = {Balkema Press}, organization = {Balkema Press}, address = {Rotterdam}, keywords = {LTER-MCM}, author = {Kepner, R.L. and Robert A. Wharton Jr. and Galchenko, V} } @article {1545, title = {Biodiversity and Ecosystem Functioning in Soil}, journal = {Ambio}, volume = {26}, year = {1997}, pages = {563-570}, keywords = {LTER-MCM}, author = {Brussaard, L and Valerie Behan-Pelletier and David E. Bignell and V.K. Brown}, editor = {W. Didden and P. Folgarait and C. Fragoso and Diana W. Freckman} } @inbook {1552, title = {Determination of rare earth elements in Antarctic lakes and streams of varying ionic strengths}, booktitle = {Plasma Source Mass Spectrometry: Developments and Applications}, year = {1997}, pages = {253-262}, publisher = {Royal Society of Chemistry}, organization = {Royal Society of Chemistry}, address = {London}, keywords = {LTER-MCM}, author = {Graham, E and Ramsey, L. A. and W. Berry Lyons and Kathleen A. Welch} } @article {1569, title = {Determination of major element chemistry in terrestrial waters from Antarctica by ion chromatography}, journal = {Journal of Chromatography A}, volume = {739}, year = {1996}, pages = {257-263}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons and Graham, E and Klaus Neumann and James M. Thomas and D. Mikesell} } @article {1584, title = {Viruses in antarctic lakes: a first assessment of their distribution}, journal = {Bulletin of the Ecological Society of America Supplement}, volume = {77}, year = {1996}, pages = {230}, keywords = {LTER-MCM}, author = {Kepner, R.L. and Robert A. Wharton Jr. and Galchenko, V} } @article {1606, title = {Streamflow, water-temperature, and specific-conductance data for selected streams draining into Lake Fryxell, Lower Taylor Valley, Victoria Land, Antarctica, 1990-92}, journal = {U.S. Geological Survey. Open-File Report 94-545}, year = {1995}, keywords = {LTER-MCM}, author = {Paul Von Guerard and Diane M. McKnight and Richard A. Harnish and J. W. Gartner and Edmund D. Andrews} }