@article {4418, title = {GIS tool to predict photosynthetically active radiation in a Dry Valley}, journal = {Antarctic Science}, year = {2020}, month = {04/2020}, abstract = {

Understanding primary productivity is a core research area of the National Science Foundation\&$\#$39;s Long-Term Ecological Research Network. This study presents the development of the GIS-based Topographic Solar Photosynthetically Active Radiation (T-sPAR) toolbox for Taylor Valley. It maps surface photosynthetically active radiation using four meteorological stations with ~20 years of data. T-sPAR estimates were validated with ground-truth data collected at Taylor Valley\&$\#$39;s major lakes during the 2014\–15 and 2015\–16 field seasons. The average daily error ranges from 0.13 mol photons m-2 day-1 (0.6\%) at Lake Fryxell to 3.8 mol photons m-2 day-1 (5.8\%) at Lake Hoare. We attribute error to variability in terrain and sun position. Finally, a user interface was developed in order to estimate total daily surface photosynthetically active radiation for any location and date within the basin. T-sPAR improves upon existing toolboxes and models by allowing for the inclusion of a statistical treatment of light attenuation due to cloud cover. The T-sPAR toolbox could be used to inform biological sampling sites based on radiation distribution, which could collectively improve estimates of net primary productivity, in some cases by up to 25\%.

}, keywords = {LTER-MCM, ArcMap, automated weather station, digital elevation model, ice-covered lakes, McMurdo Dry Valleys, R model, Taylor Valley}, doi = {10.1017/S0954102020000218}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/gis-tool-to-predict-photosynthetically-active-radiation-in-a-dry-valley/BD0BE4FF6A8F3DAAF32D698797287078}, author = {Acosta, Dimitri R. and Peter T. Doran and Myers, Madeline} } @mastersthesis {4364, title = {Groundwater and thermal legacy of a large paleolake in Taylor Valley, East Antarctica as evidenced by airborne electromagnetic and sedimentological techniques}, volume = {M.S.}, year = {2018}, month = {07/2018}, school = {Louisiana State University}, type = {masters}, address = {Baton Rouge, LA}, abstract = {

During the Last Glacial Maximum, grounded ice in the Ross Sea extended into the otherwise ice-free McMurdo Dry Valleys, creating a series of large ice dammed paleolakes. Grounded ice within the mouth of Taylor Valley allowed for lake levels to reach elevations not possible at modern day and formed what is known as Glacial Lake Washburn (GLW). GLW extended from the eastern portion of Taylor Valley roughly 20 km west to a level ~300 m higher than modern day Lake Fryxell. The formation and existence of GLW has been debated, though previous studies correlate the timing of GLW with early Holocene grounded ice. Evidence of GLW has largely been constrained to the interpretation of glacial deposits and fluvial features such as lacustrine deposits, strandlines, and preserved paleodeltas. GIS and remote sensing techniques paired with regional resistivity data provide new insight into the paleohydrology of the region.

To quantify the extent of GLW, paleodelta locations were mapped using high resolution LiDAR digital elevation models and satellite imagery. Delta topset elevations were correlated between three streams in Fryxell basin to determine paleolake levels. Additionally, mean resistivity maps generated from airborne electromagnetic survey data (SkyTEM) reveal an extensive groundwater system within Fryxell basin which is interpreted as a legacy groundwater signal from GLW. Resistivity data suggests that active permafrost formation has been ongoing since onset of lake drainage, and that lake levels were over 60 m higher than modern only 1,000 \– 2,000 yr BP. This coincides with a warmer than modern paleoclimate inferred by ice core records, indicating a dynamic hydrological system that is highly sensitive to small changes in climate. As global temperatures increase, Lake Fryxell will continue to experience highly variable lake levels. Lakes and groundwater within the McMurdo Dry Valleys are critical to understanding impacts on the broader ecosystem which is largely driven by the availability of liquid water.

}, keywords = {LTER-MCM}, url = {https://digitalcommons.lsu.edu/gradschool_theses/4776}, author = {Myers, Krista F. and Peter T. Doran} } @article {3708, title = {Growth dynamics of a laminated microbial mat in response to variable irradiance in an Antarctic lake}, journal = {Freshwater Biology}, volume = {61}, year = {2016}, month = {02/2016}, pages = {396 - 410}, abstract = {
  1. Laminated microbial mats are important ecosystem components of perennially ice-covered Antarctic dry valley lakes. In order to understand better their response to changing environment, we made observations and carried out a manipulation experiment to determine their response to variations in irradiance in Lake Hoare (77\°38\′ S, 162\°53\′ E).
  2. Ice transparency was the most variable parameter that affected benthic light dose, both spatially and between years. Patterns of lamina accrual corresponded to irradiance history, with laminae that were initiated in high transmission years thicker than those from low transmission years.
  3. A shading experiment confirmed that accrual of lamina thickness, calcite precipitation and ash-free dry mass were determined by irradiance, but photosynthetic biomass and phototrophic species composition were less affected.
  4. Buried laminae decomposed only slowly over time, with potentially viable phototrophs many laminae down into the microbial mat. Decay rate increased only slightly with shading.
  5. We conclude that the microbial mats in Lake Hoare are characterised by remarkable stability, with slow accumulation rates and turnover of biomass over time. Photosynthetic biomass and species composition appeared to be stable across long time periods, with interannual variation in lamination pattern due to differential accumulation of extracellular polysaccharide and representing the visible expression of annual growth conditions.
}, keywords = {LTER-MCM}, doi = {10.1111/fwb.2016.61.issue-410.1111/fwb.12715}, url = {http://doi.wiley.com/10.1111/fwb.12715}, author = {Ian Hawes and Jungblut, Anne D. and Maciek K. Obryk and Peter T. Doran} } @phdthesis {4097, title = {Geophysics, Water Balance, and History of Thick Perennial Ice Covers on Antarctic Lakes}, volume = {Ph.D.}, year = {2014}, school = {University of Illinois}, type = {doctoral}, address = {Chicago, IL}, abstract = {

Antarctic lakes are studied as sentinels of future change, for paleolimnological records contained in the sediments, and as habitats for the simple food webs that can exist in inhospitable environments. Understanding how lakes are formed and are sustained in response to landscape and climate conditions is critical in addressing the aforementioned research themes. This thesis is governed by the overarching hypothesis that an understanding of hydrologic and sediment transport processes associated with lake ice formation and preservation can be used to reveal past climatic changes, and further our awareness of current changes in climate and water balance in the McMurdo Dry Valleys of Antarctica. The first chapter focuses on water loss from closed basin lakes in Taylor Valley, Antarctica, and presents updated estimates of sublimation and ablation rates from long-term empirical measurements. The second and third chapters address the formation of Lake Vida, Antarctica. The former investigates the accretion of a 27 m ice cover, and considers the origin of thick sediment layers in the ice cover, and the latter uses two geophysical methods to quantify the extent and volume of the brine network in the subsurface beneath the lake. The results presented herein advance the study of hydrogeology in continuous permafrost, provide additional evidence for fluctuating climate states in the McMurdo Dry Valleys throughout the mid to late Holocene, and provide a case study for the preservation of water in a cold, desert environment analogous to neighboring planets.

}, keywords = {LTER-MCM, Antarctica, brine, lake ice, McMurdo Dry Valleys, polar lakes, sublimation}, url = {http://hdl.handle.net/10027/19407}, author = {Hilary A. Dugan}, editor = {Peter T. Doran} } @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} } @article {1269, title = {Glacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, Southern Victoria Land, Antarctica}, journal = {Palaeography, Palaeoclimatology, Palaeoecology}, volume = {341}, year = {2006}, pages = {320}, keywords = {LTER-MCM}, doi = {LTER}, author = {Wagner, B and Melles, M and Peter T. Doran and Kenig, Fabien and Forman, S and Pierau, R and Allan, P} } @article {1299, title = {Groundwater seeps in Taylor Valley Antarctica: An example of a subsurface melt event}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, pages = {200-206}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Kathleen A. Welch and Anne E. Carey and Diana H. Wall and Ross A. Virginia and Andrew G Fountain and Peter T. Doran and Csatho, B and Tremper, C} } @inbook {1332, title = {Geochronology of high latitude lake sediments}, booktitle = {Long-Term Environmental Change in Arctic and Antarctic Lakes}, year = {2004}, publisher = {Kluwer Academic Publishers}, organization = {Kluwer Academic Publishers}, keywords = {LTER-MCM}, author = {Wolf, A and Miller, G and Olsen, C and Forman, S and Peter T. Doran and Holmgren, S}, editor = {Pienitz, R and Douglas, Marianne S. V. and J.P. Smol} }