@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 {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 {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} } @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} } @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} }