USAP-DC

{"dp_type": "Dataset", "free_text": "Crust"}

[{"awards": "2044924 Barrett, John", "bounds_geometry": ["POLYGON((161.70776367188 -77.519802097166,161.899475097661 -77.519802097166,162.091186523442 -77.519802097166,162.282897949223 -77.519802097166,162.474609375004 -77.519802097166,162.666320800785 -77.519802097166,162.858032226566 -77.519802097166,163.049743652347 -77.519802097166,163.241455078128 -77.519802097166,163.433166503909 -77.519802097166,163.62487792969 -77.519802097166,163.62487792969 -77.54867059480199,163.62487792969 -77.57753909243799,163.62487792969 -77.606407590074,163.62487792969 -77.63527608771,163.62487792969 -77.664144585346,163.62487792969 -77.69301308298199,163.62487792969 -77.72188158061799,163.62487792969 -77.750750078254,163.62487792969 -77.77961857589,163.62487792969 -77.808487073526,163.433166503909 -77.808487073526,163.241455078128 -77.808487073526,163.049743652347 -77.808487073526,162.858032226566 -77.808487073526,162.666320800785 -77.808487073526,162.474609375004 -77.808487073526,162.282897949223 -77.808487073526,162.091186523442 -77.808487073526,161.899475097661 -77.808487073526,161.70776367188 -77.808487073526,161.70776367188 -77.77961857589,161.70776367188 -77.750750078254,161.70776367188 -77.72188158061799,161.70776367188 -77.69301308298199,161.70776367188 -77.664144585346,161.70776367188 -77.63527608771,161.70776367188 -77.606407590074,161.70776367188 -77.57753909243799,161.70776367188 -77.54867059480199,161.70776367188 -77.519802097166))"], "date_created": "Wed, 03 Apr 2024 00:00:00 GMT", "description": "Microbial communities are the primary drivers of carbon cycling in the McMurdo Dry Valleys of Antarctica. Dense microbial mats, consisting mainly of photosynthetic cyanobacteria, occupy aquatic areas associated with streams and lakes. Other microbial communities also occur at lower densities as patchy surface biological soil crusts (biocrusts) across the terrestrial landscape. Multispectral satellite data have been used to model microbial mat abundance in high-density areas like stream and lake margins, but no previous studies had investigated the lower detection limits of biocrusts. Here, we describe remote sensing and field-based survey and sampling approaches to study the detectability and distribution of biocrusts in the McMurdo Dry Valleys. Using a combination of multi- and hyperspectral tools and spectral linear unmixing, we modeled the abundances of biocrust in eastern Taylor Valley. Our spectral approaches can detect low masses of biocrust material in laboratory microcosms down to biocrust concentrations of 1% by mass. These techniques also distinguish the spectra of biocrust from both surface rock and mineral signatures from orbit. We found that biocrusts are present throughout the soils of eastern Taylor Valley and are associated with diverse underlying soil communities. The densest biocrust communities identified in this study had total organic carbon 5x greater than the content of typical arid soils. The most productive biocrusts were located downslope of melting snowpacks in unique soil ecosystems that are distinct from the surrounding arid landscape. There are similarities between the snowpack and stream sediment communities (high diversity of soil invertebrates) as well as their ecosystem properties (e.g., persistence of liquid water, high transfer of available nutrients, lower salinity from flushing) compared to the typical arid terrestrial ecosystem of the dry valleys. Our approach extends the capability of orbital remote sensing of photosynthetic communities out of the aquatic margins and into the drier soils which comprise most of this landscape. This interdisciplinary work is critical for measuring and monitoring terrestrial carbon stocks and predicting future ecosystem dynamics in this currently water-limited but increasingly dynamic Antarctic landscape, which is particularly climate-sensitive and difficult to access.\r\n", "east": 163.62487792969, "geometry": ["POINT(162.666320800785 -77.664144585346)"], "keywords": "Antarctica; Carbon; Cryosphere; McMurdo Dry Valleys; Snow", "locations": "McMurdo Dry Valleys; Antarctica", "north": -77.519802097166, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "persons": "Barrett, John", "project_titles": null, "projects": null, "repositories": null, "science_programs": null, "south": -77.808487073526, "title": "Hyperspectral reflectance values and biophysicochemical properties of biocrusts and soils in the Fryxell Basin, McMurdo Dry Valleys, Antarctica", "uid": "601773", "west": 161.70776367188}, {"awards": "1848887 McClintock, James", "bounds_geometry": ["POLYGON((-64.06 -64.76,-64.059 -64.76,-64.058 -64.76,-64.057 -64.76,-64.056 -64.76,-64.055 -64.76,-64.054 -64.76,-64.053 -64.76,-64.05199999999999 -64.76,-64.051 -64.76,-64.05 -64.76,-64.05 -64.76100000000001,-64.05 -64.762,-64.05 -64.763,-64.05 -64.764,-64.05 -64.765,-64.05 -64.766,-64.05 -64.767,-64.05 -64.768,-64.05 -64.76899999999999,-64.05 -64.77,-64.051 -64.77,-64.05199999999999 -64.77,-64.053 -64.77,-64.054 -64.77,-64.055 -64.77,-64.056 -64.77,-64.057 -64.77,-64.058 -64.77,-64.059 -64.77,-64.06 -64.77,-64.06 -64.76899999999999,-64.06 -64.768,-64.06 -64.767,-64.06 -64.766,-64.06 -64.765,-64.06 -64.764,-64.06 -64.763,-64.06 -64.762,-64.06 -64.76100000000001,-64.06 -64.76))"], "date_created": "Thu, 22 Jun 2023 00:00:00 GMT", "description": "These data are counts of amphipods that had been maintained under ambient pH (8.0 to 8.1) and experimental pH levels of 7.7 (potential end-of-century ocean acidification conditions) and 7.3 (potential next-century conditions). The amphipods were collected from the brown macroalga Desmarestia menziesii and placed into experimental containers (5-gallon buckets) for 5-6 weeks (experimental period significantly shortened by COVID complications). D. menziesii was also present in the buckets and the density of amphipods on the macroalgae was the same as it was in the field collections. The dataset includes counts of amphipods in the initial conditions and at the end of the experiment from the three pH levels.", "east": -64.05, "geometry": ["POINT(-64.055 -64.765)"], "keywords": "Antarctica; Palmer Station", "locations": "Palmer Station; Antarctica", "north": -64.76, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "persons": "Amsler, Charles", "project_titles": "Assemblage-wide effects of ocean acidification and ocean warming on ecologically important macroalgal-associated crustaceans in Antarctica", "projects": [{"proj_uid": "p0010193", "repository": "USAP-DC", "title": "Assemblage-wide effects of ocean acidification and ocean warming on ecologically important macroalgal-associated crustaceans in Antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -64.77, "title": "Amphipod counts from 2020 ocean acidification experiment", "uid": "601702", "west": -64.06}, {"awards": "1848887 McClintock, James", "bounds_geometry": ["POLYGON((-64.06 -64.76,-64.058 -64.76,-64.056 -64.76,-64.054 -64.76,-64.052 -64.76,-64.05000000000001 -64.76,-64.048 -64.76,-64.046 -64.76,-64.04400000000001 -64.76,-64.042 -64.76,-64.04 -64.76,-64.04 -64.76100000000001,-64.04 -64.762,-64.04 -64.763,-64.04 -64.764,-64.04 -64.765,-64.04 -64.766,-64.04 -64.767,-64.04 -64.768,-64.04 -64.76899999999999,-64.04 -64.77,-64.042 -64.77,-64.04400000000001 -64.77,-64.046 -64.77,-64.048 -64.77,-64.05000000000001 -64.77,-64.052 -64.77,-64.054 -64.77,-64.056 -64.77,-64.058 -64.77,-64.06 -64.77,-64.06 -64.76899999999999,-64.06 -64.768,-64.06 -64.767,-64.06 -64.766,-64.06 -64.765,-64.06 -64.764,-64.06 -64.763,-64.06 -64.762,-64.06 -64.76100000000001,-64.06 -64.76))"], "date_created": "Thu, 22 Jun 2023 00:00:00 GMT", "description": "", "east": -64.04, "geometry": ["POINT(-64.05000000000001 -64.765)"], "keywords": "Antarctica; Palmer Station", "locations": "Palmer Station; Antarctica", "north": -64.76, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "persons": "Amsler, Charles", "project_titles": "Assemblage-wide effects of ocean acidification and ocean warming on ecologically important macroalgal-associated crustaceans in Antarctica", "projects": [{"proj_uid": "p0010193", "repository": "USAP-DC", "title": "Assemblage-wide effects of ocean acidification and ocean warming on ecologically important macroalgal-associated crustaceans in Antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -64.77, "title": "2023 daily seawater carbonate chemistry", "uid": "601701", "west": -64.06}, {"awards": "1848887 McClintock, James", "bounds_geometry": ["POLYGON((-64.06 -64.76,-64.058 -64.76,-64.056 -64.76,-64.054 -64.76,-64.052 -64.76,-64.05000000000001 -64.76,-64.048 -64.76,-64.046 -64.76,-64.04400000000001 -64.76,-64.042 -64.76,-64.04 -64.76,-64.04 -64.76100000000001,-64.04 -64.762,-64.04 -64.763,-64.04 -64.764,-64.04 -64.765,-64.04 -64.766,-64.04 -64.767,-64.04 -64.768,-64.04 -64.76899999999999,-64.04 -64.77,-64.042 -64.77,-64.04400000000001 -64.77,-64.046 -64.77,-64.048 -64.77,-64.05000000000001 -64.77,-64.052 -64.77,-64.054 -64.77,-64.056 -64.77,-64.058 -64.77,-64.06 -64.77,-64.06 -64.76899999999999,-64.06 -64.768,-64.06 -64.767,-64.06 -64.766,-64.06 -64.765,-64.06 -64.764,-64.06 -64.763,-64.06 -64.762,-64.06 -64.76100000000001,-64.06 -64.76))"], "date_created": "Thu, 22 Jun 2023 00:00:00 GMT", "description": "Results of daily monitoring of carbonate chemistry parameters in experimental containers (buckets).", "east": -64.04, "geometry": ["POINT(-64.05000000000001 -64.765)"], "keywords": "Antarctica; Palmer Station", "locations": "Palmer Station; Antarctica", "north": -64.76, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "persons": "Amsler, Charles", "project_titles": "Assemblage-wide effects of ocean acidification and ocean warming on ecologically important macroalgal-associated crustaceans in Antarctica", "projects": [{"proj_uid": "p0010193", "repository": "USAP-DC", "title": "Assemblage-wide effects of ocean acidification and ocean warming on ecologically important macroalgal-associated crustaceans in Antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -64.77, "title": "2020 daily seawater carbonate chemistry", "uid": "601700", "west": -64.06}, {"awards": "0944150 Hall, Brenda; 1643248 Hall, Brenda", "bounds_geometry": ["POLYGON((164 -78,164.04 -78,164.08 -78,164.12 -78,164.16 -78,164.2 -78,164.24 -78,164.28 -78,164.32 -78,164.36 -78,164.4 -78,164.4 -78.01,164.4 -78.02,164.4 -78.03,164.4 -78.04,164.4 -78.05,164.4 -78.06,164.4 -78.07,164.4 -78.08,164.4 -78.09,164.4 -78.1,164.36 -78.1,164.32 -78.1,164.28 -78.1,164.24 -78.1,164.2 -78.1,164.16 -78.1,164.12 -78.1,164.08 -78.1,164.04 -78.1,164 -78.1,164 -78.09,164 -78.08,164 -78.07,164 -78.06,164 -78.05,164 -78.04,164 -78.03,164 -78.02,164 -78.01,164 -78))"], "date_created": "Tue, 01 Mar 2022 00:00:00 GMT", "description": "This dataset includes 234U/230Th chronologic data for lacustrine carbonates associated with Marshall drift in Marshall Valley, Royal Society Range. These samples are from ice-dammed lake deposits associated with a grounded ice sheet that blocked the valley mouth. Sample chemistry was done at the University of Maine geochemistry laboratory. Processed samples were analyzed on a multicollector ICP-MS at the University of Oxford. Corrected ages reflect a detrital correction based on typical upper-crustal (230Th/232Th) values of 1.21 with a 50% assumed error.", "east": 164.4, "geometry": ["POINT(164.2 -78.05)"], "keywords": "234U/230Th Dating; Antarctica; Glaciers/Ice Sheet; Glaciology; Last Glacial Maximum; Marshall Drift; Marshall Valley; MIS 6; Royal Society Range", "locations": "Marshall Valley; Royal Society Range; Antarctica", "north": -78.0, "nsf_funding_programs": "Antarctic Earth Sciences; Antarctic Glaciology", "persons": "Hall, Brenda", "project_titles": "Response of the Antarctic Ice Sheet to the last great global warming; Sensitivity of the Antarctic Ice Sheet to Climate Change over the Last Two Glacial/Interglacial Cycles", "projects": [{"proj_uid": "p0010301", "repository": "USAP-DC", "title": "Response of the Antarctic Ice Sheet to the last great global warming"}, {"proj_uid": "p0010302", "repository": "USAP-DC", "title": "Sensitivity of the Antarctic Ice Sheet to Climate Change over the Last Two Glacial/Interglacial Cycles"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -78.1, "title": "Marshall Valley U-Series Data", "uid": "601528", "west": 164.0}, {"awards": "1643795 Mikesell, Thomas", "bounds_geometry": ["POLYGON((-134.5 -75,-130.85 -75,-127.2 -75,-123.55 -75,-119.9 -75,-116.25 -75,-112.6 -75,-108.95 -75,-105.3 -75,-101.65 -75,-98 -75,-98 -75.85,-98 -76.7,-98 -77.55,-98 -78.4,-98 -79.25,-98 -80.1,-98 -80.95,-98 -81.8,-98 -82.65,-98 -83.5,-101.65 -83.5,-105.3 -83.5,-108.95 -83.5,-112.6 -83.5,-116.25 -83.5,-119.9 -83.5,-123.55 -83.5,-127.2 -83.5,-130.85 -83.5,-134.5 -83.5,-134.5 -82.65,-134.5 -81.8,-134.5 -80.95,-134.5 -80.1,-134.5 -79.25,-134.5 -78.4,-134.5 -77.55,-134.5 -76.7,-134.5 -75.85,-134.5 -75))"], "date_created": "Fri, 15 Jan 2021 00:00:00 GMT", "description": "This data set includes observations of Rayleigh and Love wave group and phase velocity dispersion curves from ambient noise crosscorrelation functions. The data set includes the corresponding shear wave velocity model produced by joint inversion of these dispersion curves. This investigators developed a new crust and upper mantle model directly beneath the seismic stations used in this study. Data are in NetCDF and GeoCSV formats. The Python code used to generate the NetCDF files from the GeoCSV files is also contained in the data set.", "east": -98.0, "geometry": ["POINT(-116.25 -79.25)"], "keywords": "Antarctica; Crust; Moho; Seismic Tomography; Seismology; Seismometer; Shear wave velocity; Surface Wave Dispersion; West Antarctica", "locations": "West Antarctica; Antarctica", "north": -75.0, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "Mikesell, Dylan", "project_titles": "Collaborative Research: Monitoring Antarctic Ice Sheet Changes with Ambient Seismic Noise Methods", "projects": [{"proj_uid": "p0010155", "repository": "USAP-DC", "title": "Collaborative Research: Monitoring Antarctic Ice Sheet Changes with Ambient Seismic Noise Methods"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "POLENET", "south": -83.5, "title": "2D shear-wave velocity model across the West Antarctic Rift System from POLENET-ANET seismic data", "uid": "601423", "west": -134.5}, {"awards": "0542456 Caron, David; 0538148 Huber, Bruce", "bounds_geometry": ["POLYGON((169 -70.5,169.4 -70.5,169.8 -70.5,170.2 -70.5,170.6 -70.5,171 -70.5,171.4 -70.5,171.8 -70.5,172.2 -70.5,172.6 -70.5,173 -70.5,173 -70.65,173 -70.8,173 -70.95,173 -71.1,173 -71.25,173 -71.4,173 -71.55,173 -71.7,173 -71.85,173 -72,172.6 -72,172.2 -72,171.8 -72,171.4 -72,171 -72,170.6 -72,170.2 -72,169.8 -72,169.4 -72,169 -72,169 -71.85,169 -71.7,169 -71.55,169 -71.4,169 -71.25,169 -71.1,169 -70.95,169 -70.8,169 -70.65,169 -70.5))"], "date_created": "Thu, 25 Jun 2020 00:00:00 GMT", "description": "This data set was acquired with a CurrentMeter during Nathaniel B. Palmer expedition NBP0801 conducted in 2008 (Chief Scientist: Dr. David Caron; Investigator(s): Dr. Bruce Huber and Dr. Arnold Gordon). These data files are of Matlab Binary format and include Current Measurement, Salinity, and Temperature data and were processed after data collection. Data were acquired as part of the project(s): Cape Adare Long-term Mooring (CALM) and Collaborative Research:Do crustacean zooplankton play a pivotal role in structuring heterotrophic plankton communities., and funding was provided by NSF grant(s): ANT05-38148 and ANT05-42456.", "east": 173.0, "geometry": ["POINT(171 -71.25)"], "keywords": "Antarctica; Cape Adare; Mooring; NBP0801; Physical Oceanography; Ross Sea; R/V Nathaniel B. Palmer; Salinity; Southern Ocean; Temperature", "locations": "Antarctica; Southern Ocean; Cape Adare; Ross Sea; Ross Sea; Cape Adare; Antarctica", "north": -70.5, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences; Antarctic Ocean and Atmospheric Sciences", "persons": "Huber, Bruce; Gordon, Arnold", "project_titles": "Cape Adare Long-term Mooring (CALM); Collaborative Research: Do Crustacean Zooplankton Play a Pivotal Role in Structuring Heterotrophic Plankton Communities in the Ross Sea?", "projects": [{"proj_uid": "p0000520", "repository": "USAP-DC", "title": "Collaborative Research: Do Crustacean Zooplankton Play a Pivotal Role in Structuring Heterotrophic Plankton Communities in the Ross Sea?"}, {"proj_uid": "p0000838", "repository": "USAP-DC", "title": "Cape Adare Long-term Mooring (CALM)"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -72.0, "title": "Processed CurrentMeter Data from the Ross Sea near Antarctica acquired during the Nathaniel B. Palmer expedition NBP0801", "uid": "601344", "west": 169.0}, {"awards": "1148982 Hansen, Samantha", "bounds_geometry": ["POLYGON((150 -72,152 -72,154 -72,156 -72,158 -72,160 -72,162 -72,164 -72,166 -72,168 -72,170 -72,170 -72.3,170 -72.6,170 -72.9,170 -73.2,170 -73.5,170 -73.8,170 -74.1,170 -74.4,170 -74.7,170 -75,168 -75,166 -75,164 -75,162 -75,160 -75,158 -75,156 -75,154 -75,152 -75,150 -75,150 -74.7,150 -74.4,150 -74.1,150 -73.8,150 -73.5,150 -73.2,150 -72.9,150 -72.6,150 -72.3,150 -72))"], "date_created": "Wed, 31 Jul 2019 00:00:00 GMT", "description": "The Transantarctic Mountains (TAMs) are the largest non-collisional mountain range on Earth. Their origin, as well as the origin of the Wilkes Subglacial Basin (WSB) along the inland side of the TAMs, have been widely debated, and a key constraint to distinguish between competing models is the underlying crustal structure. Previous investigations have examined this structure but have primarily focused on a small region of the central TAMs near Ross Island, providing little along-strike constraint. In this study, we use data from the new Transantarctic Mountains Northern Network and from five stations operated by the Korea Polar Research Institute to investigate the crustal structure beneath a previously unexplored portion of the TAMs. Using S-wave receiver functions and Rayleigh wave phase velocities, crustal thickness and average crustal shear velocity (\uf8e5Vs) are resolved within \u00b14 km and \u00b10.1 km/s, respectively. The crust thickens from ~20 km near the Ross Sea coast to ~46 km beneath the northern TAMs, which is somewhat thicker than that imaged in previous studies beneath the central TAMs. The crust thins to ~41 km beneath the WSB.\uf8e5Vs ranges from ~3.1-3.9 km/s, with slower velocities near the coast. Our findings are consistent with a flexural origin for the TAMs and WSB, where these features result from broad flexure of the East Antarctic lithosphere and uplift along its western edge due to thermal conduction from hotter mantle beneath West Antarctica. Locally thicker crust may explain the ~1 km of additional topography in the northern TAMs compared to the central TAMs.", "east": 170.0, "geometry": ["POINT(160 -73.5)"], "keywords": "Antarctica; Transantarctic Mountains", "locations": "Transantarctic Mountains; Antarctica", "north": -72.0, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "Hansen, Samantha", "project_titles": "CAREER: Deciphering the Tectonic History of the Transantarctic Mountains and the Wilkes Subglacial Basin", "projects": [{"proj_uid": "p0000300", "repository": "USAP-DC", "title": "CAREER: Deciphering the Tectonic History of the Transantarctic Mountains and the Wilkes Subglacial Basin"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -75.0, "title": "Crustal Structure beneath the Northern Transantarctic Mountains and Wilkes Subglacial Basin: Implications for Tectonic Origins", "uid": "601194", "west": 150.0}, {"awards": "1043528 Alley, Richard", "bounds_geometry": ["POINT(-112.085 -79.467)"], "date_created": "Tue, 16 Jan 2018 00:00:00 GMT", "description": "This dataset includes all surface, snowpit, crust, AWS, and near-surface thermistor data used for analyses and publication \"Surface formation, preservation, and history of low-porosity crusts at the WAIS Divide site, West Antarctica\" DOI: https://doi.org/10.5194/tc-12-1-2018", "east": -112.085, "geometry": ["POINT(-112.085 -79.467)"], "keywords": "Antarctica; Atmosphere; AWS; Glaciers/Ice Sheet; Glaciology; Ice Core Records; Meteorology; Physical Properties; Snow Pit; Temperature; WAIS divide; WAIS Divide Ice Core; WeatherStation", "locations": "WAIS divide; Antarctica", "north": -79.467, "nsf_funding_programs": "Antarctic Ocean and Atmospheric Sciences", "persons": "Fegyveresi, John; Alley, Richard", "project_titles": "Collaborative Research: Continued Study of Physical Properties of the WAIS Divide Deep Core; Collaborative Research: Physical Properties of the WAIS Divide Deep Core", "projects": [{"proj_uid": "p0000027", "repository": "USAP-DC", "title": "Collaborative Research: Continued Study of Physical Properties of the WAIS Divide Deep Core"}, {"proj_uid": "p0000038", "repository": "USAP-DC", "title": "Collaborative Research: Physical Properties of the WAIS Divide Deep Core"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "WAIS Divide Ice Core", "south": -79.467, "title": "WAIS Divide Surface and Snow-pit Data, 2009-2013", "uid": "601079", "west": -112.085}, {"awards": "1043750 Chen, Jianli", "bounds_geometry": ["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"], "date_created": "Fri, 01 Jan 2016 00:00:00 GMT", "description": "This award supports a project to improve the estimate of long-term and inter-annual variability of Antarctic ice sheet mass balance at continental, regional, and catchment scales, using satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) and other geodetic measurements. The work will improve the quantification of long-term mass change rates over Antarctica using GRACE gravity data with a longer record and newer generation(s) of products and will develop advanced numerical forward modeling techniques that can accurately correct leakage effects associated with GRACE data processing, and significantly improve spatial resolution of GRACE mass rate estimates over Antarctica. The work will also contribute to a better understanding of crustal uplift rates due to postglacial rebound (PGR) and present day ice load change over Antarctica via PGR models, GPS measurements, and combined analysis of GRACE and ICESat elevation changes. Inter-annual variations of ice mass over Antarctica will be investigated at continental and catchment scales and connections to regional climate change will be studied. The major deliverables from this study will be improved assessments of ice mass balance for the entire Antarctic ice sheet and potential contribution to global mean sea level rise. The work will also provide estimates of regional ice mass change rates over Antarctica, with a focus along the coast in the Amundsen Sea Embayment, the Peninsula in West Antarctica, and in Wilkes Land and Victoria Land in East Antarctica. Estimates of inter-annual ice mass change over Antarctica at various spatial scales, and assessments of uncertainty of GRACE ice rate estimates and PGR models errors over Antarctica will also be made. The intellectual merits of the proposed investigation include 1) providing improved assessments of Antarctic ice mass balance at different temporal and spatial scales with unprecedented accuracy, an important contribution to broad areas of polar science research; 2) combining high accuracy GPS vertical uplift measurements and PGR models to better quantify long-term crust uplift effects that are not distinguishable from ice mass changes by GRACE; and 3) unifying the work of several investigations at the forefront of quantifying ice sheet and glacier mass balance and crustal uplift based on a variety of modern space geodetic observations. The broader impacts include the fact that the project will actively involve student participation and training, through the support of two graduate students. In addition the project will contribute to general education and public outreach (E/PO) activities and the results from this investigation will help inspire future geoscientists and promote public awareness of significant manifestations of climate change.", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Antarctica; Glaciers/Ice Sheet; Glaciology; GPS; GRACE; Potential Field; Satellite Data", "locations": "Antarctica", "north": -60.0, "nsf_funding_programs": null, "persons": "Chen, Jianli", "project_titles": "Collaborative Research: Long-Term and Interannual Variability of Antarctic Ice Sheet Mass Balance From Satellite Gravimetry and Other Geodetic Measurements", "projects": [{"proj_uid": "p0000415", "repository": "USAP-DC", "title": "Collaborative Research: Long-Term and Interannual Variability of Antarctic Ice Sheet Mass Balance From Satellite Gravimetry and Other Geodetic Measurements"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Long-Term and Interannual Variability of Antarctic Ice Sheet Mass Balance From Satellite Gravimetry and Other Geodetic Measurements", "uid": "600159", "west": -180.0}, {"awards": "1142156 Marschall, Horst", "bounds_geometry": ["POLYGON((-6.44 -71.93,-5.378 -71.93,-4.316 -71.93,-3.254 -71.93,-2.192 -71.93,-1.13 -71.93,-0.068 -71.93,0.994 -71.93,2.056 -71.93,3.118 -71.93,4.18 -71.93,4.18 -71.998,4.18 -72.066,4.18 -72.134,4.18 -72.202,4.18 -72.27,4.18 -72.338,4.18 -72.406,4.18 -72.474,4.18 -72.542,4.18 -72.61,3.118 -72.61,2.056 -72.61,0.994 -72.61,-0.068 -72.61,-1.13 -72.61,-2.192 -72.61,-3.254 -72.61,-4.316 -72.61,-5.378 -72.61,-6.44 -72.61,-6.44 -72.542,-6.44 -72.474,-6.44 -72.406,-6.44 -72.338,-6.44 -72.27,-6.44 -72.202,-6.44 -72.134,-6.44 -72.066,-6.44 -71.998,-6.44 -71.93))"], "date_created": "Thu, 01 Jan 2015 00:00:00 GMT", "description": "Geochemical studies of single mineral grains in rocks can be probed to reconstruct the history of our planet. The mineral zircon (ZrSiO4) is of unique importance in that respect because of its reliability as a geologic clock due to its strong persistence against weathering, transport and changes in temperature and pressure. Uranium-Lead (U-Pb) dating of zircon grains is, perhaps, the most frequently employed method of extracting time information on geologic processes that shaped the continental crust, and has been used to constrain the evolution of continents and mountain belts through time. In addition, the isotopic composition of the element Hafnium (Hf) in zircon is used to date when the continental crust was generated by extraction of magma from the underlying mantle. Melting of rocks in the mantle and deep in the continental crust are key processes in the evolution of the continents, and they are recorded in the Hf isotopic signatures of zircon. Although the analytical procedures for U-Pb dating and Hf isotope analyses of zircon are robust now, our understanding of zircon growth and its exchange of elements and isotopes with its surrounding rock or magma are still underdeveloped. The focus of the proposed study, therefore, is to unravel the evolution of zircon Hf isotopes in rocks that were formed deep in the Earth\u0027s crust, and more specifically, to apply these isotopic methods to rocks collected in Dronning Maud Land (DML), East Antarctica.\n\nDronning Maud Land (DML) occupied a central location during the formation of supercontinents - large landmasses made up of all the continents that exist today - more than 500 million years ago. It is currently thought that supercontinents were formed and dismembered five or six times throughout Earth\u0027s history. The area of DML is key for understanding the formation history of the last two supercontinents. The boundaries of continents that were merged to form those supercontinents are most likely hidden in DML. In this study, the isotopic composition of zircon grains recovered from DML rocks will be employed to identify these boundaries across an extensive section through the area. The rock samples were collected by the investigator during a two-month expedition to Antarctica in the austral summer of 2007-2008. The results of dating and isotope analyses of zircon of the different DML crustal domains will deliver significant insight into the regional geology of East Antarctica and its previous northern extension into Africa. This has significance for the reconstruction of the supercontinents and defining the continental boundaries in DML.\n", "east": 4.18, "geometry": ["POINT(-1.13 -72.27)"], "keywords": "Antarctica; Chemistry:Rock; Dronning Maud Land; Geochemistry; Geochronology; Solid Earth", "locations": "Dronning Maud Land; Antarctica", "north": -71.93, "nsf_funding_programs": null, "persons": "Marschall, Horst", "project_titles": "Zircon Hf Isotopes and the Continental Evolution of Dronning Maud Land, East Antacrtica", "projects": [{"proj_uid": "p0000448", "repository": "USAP-DC", "title": "Zircon Hf Isotopes and the Continental Evolution of Dronning Maud Land, East Antacrtica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -72.61, "title": "Zircon Hf Isotopes and the Continental Evolution of Dronning Maud Land, East Antarctica", "uid": "600135", "west": -6.44}, {"awards": "1043690 Scherer, Reed", "bounds_geometry": ["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"], "date_created": "Wed, 01 Jan 2014 00:00:00 GMT", "description": "Intellectual Merit: Diatom abundance in sediment cores is typically used as a proxy for paleo primary productivity. This record is complicated by variable preservation, with most loss occurring in the water column via dissolution and zooplankton grazing. This study will investigate preservational biases via a series of controlled experiments to create proxies of original productivity based on morphological changes associated with diatom dissolution and fracture. The PIs will utilize fresh diatoms from culture. Specific objectives include: (1) Linking changes in diatom morphology to availability of dissolved silica and other physical and chemical parameters; (2) Documenting the dissolution process under controlled conditions; (3) Assessment of changes in morphology and diatom surface roughness with increased dissolution; (4) Documenting the physical effects of grazing and fecal pellet formation on diatom fragmentation and dissolution; and (5) Analyzing the impact of diatom dissolution on silica and carbon export. These objectives will be achieved by growing Southern Ocean diatom species in the laboratory under differing physical and chemical conditions; controlled serial dissolution experiments on cultured diatoms; analysis of the dissolution process by imaging frustules under scanning electron microscopy (SEM) and with micro-analysis of surface texture by atomic force microscopy (AFM); making the cultures available to krill and other live zooplankton crustaceans in order to analyze the specific effects of grazing and pelletization on diatom morphology; and comparing experimental results with natural plankton, sediment trap material, and selected Holocene, Pleistocene and Pliocene sediment core material.\nBroader impacts: This work will contribute to understanding of the use of diatom abundance as an indicator of paleoproductivity. The proposed experiments are multi-disciplinary in nature. Importantly, the project was designed, and the proposal largely written, by a Ph.D. candidate. The research proposed here will lead to peer-reviewed publications and provide a base for future studies over the course of an extremely promising scientific career. The project will also support an undergraduate research student at NIU. The PI is heavily involved in science outreach, including classroom visits, museum events and webinars related to evolution and climate change, and is active with NSF-funded outreach activities linked to the ANDRILL and WISSARD programs. He will continue these efforts with this project.", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Antarctica; Biota; Diatom; Marine Sediments; Oceans; Sediment Core; Southern Ocean", "locations": "Antarctica; Southern Ocean", "north": -60.0, "nsf_funding_programs": null, "persons": "Haji-Sheikh, Michael; Scherer, Reed Paul", "project_titles": "Southern Ocean Diatom Taphonomy and Paleoproductivity: A Laboratory Study of Silica Degradation and Export", "projects": [{"proj_uid": "p0000360", "repository": "USAP-DC", "title": "Southern Ocean Diatom Taphonomy and Paleoproductivity: A Laboratory Study of Silica Degradation and Export"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Southern Ocean Diatom Taphonomy and Paleoproductivity: A Laboratory Study of Silica Degradation and Export", "uid": "600127", "west": -180.0}, {"awards": "1043700 Harry, Dennis", "bounds_geometry": ["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"], "date_created": "Wed, 01 Jan 2014 00:00:00 GMT", "description": "Intellectual Merit: This research will place the subsidence history of the southern Victoria Land Basin into a quantitative geodynamic context and will assess the influence of flexure associated with late Neogene volcanic loading of the crust by the Erebus Volcanic Group. This will be done by extending geodynamic models of extension in the West Antarctic Rift System to include extensional hiatuses hypothesized to have occurred during the Late Paleogene and Miocene, and by developing a new geodynamic model of volcanic loading and associated lithosphere flexure. Finite element and finite difference modeling methods will be used. In the first phase of the project, a series of extensional geodynamic models will be developed to examine the effect that proposed extensional hiatuses have on the style of extension, with emphasis placed on developing a process based understanding of the change in rift style from diffuse during the Late Cretaceous to more focused during the Cenozoic. The models will test the hypotheses that extensional hiatuses led to the change in rifting style, and will place constraints on the timing and duration of the hiatuses. The second phase of the project will use the thermal and rheological properties of the previous models to constrain the flexural rigidity of the lithosphere in order to model the flexural response to volcanic loading to test the hypotheses that flexural subsidence contributed to cyclic changes between grounded and floating ice at the ANDRILL AND-1A site, complicating interpretations of the climatic record from this core, and that flexure contributes to the stress orientation at the AND-2B site, which is inconsistent with the expected regional extensional stress orientation. Broader impacts: The project will train an undergraduate student and an M.S. student. Outreach activities include a planned series of talks at regional high schools, junior colleges, and 4-year colleges that have geology programs.\n", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "ANDRILL; Antarctica; Continental Rift; Geology/Geophysics - Other; Lithosphere; Model; Ross Sea; Solid Earth; Tectonic; Transantarctic Mountains", "locations": "Ross Sea; Transantarctic Mountains; Antarctica", "north": -60.0, "nsf_funding_programs": null, "persons": "Harry, Dennis L.", "project_titles": "Geodynamic Models of Subsidence and Lithospheric Flexure at the ANDRILL Drill Sites: Implications for Cenozoic Tectonics and Ice Sheet History", "projects": [{"proj_uid": "p0000467", "repository": "USAP-DC", "title": "Geodynamic Models of Subsidence and Lithospheric Flexure at the ANDRILL Drill Sites: Implications for Cenozoic Tectonics and Ice Sheet History"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": "ANDRILL", "south": -90.0, "title": "Geodynamic Models of Subsidence and Lithospheric Flexure at the ANDRILL Drill Sites: Implications for Cenozoic Tectonics and Ice Sheet History", "uid": "600128", "west": -180.0}, {"awards": "0838914 Wannamaker, Philip", "bounds_geometry": ["POLYGON((141.01732 -82.13,144.910279 -82.13,148.803238 -82.13,152.696197 -82.13,156.589156 -82.13,160.482115 -82.13,164.375074 -82.13,168.268033 -82.13,172.160992 -82.13,176.053951 -82.13,179.94691 -82.13,179.94691 -82.351835,179.94691 -82.57367,179.94691 -82.795505,179.94691 -83.01734,179.94691 -83.239175,179.94691 -83.46101,179.94691 -83.682845,179.94691 -83.90468,179.94691 -84.126515,179.94691 -84.34835,176.053951 -84.34835,172.160992 -84.34835,168.268033 -84.34835,164.375074 -84.34835,160.482115 -84.34835,156.589156 -84.34835,152.696197 -84.34835,148.803238 -84.34835,144.910279 -84.34835,141.01732 -84.34835,141.01732 -84.126515,141.01732 -83.90468,141.01732 -83.682845,141.01732 -83.46101,141.01732 -83.239175,141.01732 -83.01734,141.01732 -82.795505,141.01732 -82.57367,141.01732 -82.351835,141.01732 -82.13))"], "date_created": "Sun, 01 Jan 2012 00:00:00 GMT", "description": "The investigators will examine competing hypotheses for the mechanism of extension and creation of the Transantarctic Mountains, and evolution of the thermal regimes of rifted West Antarctica and stable East Antarctica using magnetotelluric (MT) profiles. Surrounded almost entirely by ocean ridges, Antarctica is a special tectonic situation because of the need to make accommodation space for rifting in the Transantarctic region. In the MT method, temporal variations in the Earth\u0027s natural electromagnetic field are used as source fields to probe the electrical resistivity structure in the depth range of 1 to 200 km, or more. Geophysical methods, such as MT, are appropriate in Antarctica because of the predominance of thick ice cover over most of the Continent and the difficult operating environment. The proposed effort will consist of approximately 50 sites over a distance approaching 500 km with a 10 km average spacing, oriented normal to the Transantarctic Mountains (TAM), in the Beardmore glacier area. High quality MT soundings will be collected over thick ice sheets using a custom electrode preamp design, updated from previous Antarctic projects. Data acquisition will take place over two field seasons. The primary goals are three-fold: to establish the location of the deeper tectonic transition between East and West Antarctica that may be offset from the physiographic transition at the surface, using deep resistivity structure distinguish between modes of extensional upwelling and magmatism that may be vertically non-uniform, depth and magnitude of quasi-layered deep crustal low resistivity, particularly below West Antarctica, will be used to estimate crustal heat flux into the ice sheet base.\n", "east": 179.94691, "geometry": ["POINT(160.482115 -83.239175)"], "keywords": "Antarctica; Magnetotelluric; Potential Field; Solid Earth; Transantarctic Mountains", "locations": "Transantarctic Mountains; Antarctica", "north": -82.13, "nsf_funding_programs": null, "persons": "Wannamaker, Philip", "project_titles": "Rift Mechanisms and Thermal Regime of the Lithosphere across Beardmore Glacier Region, Central Transantarctic Mountains, from Magnetotelluric Measurements", "projects": [{"proj_uid": "p0000247", "repository": "USAP-DC", "title": "Rift Mechanisms and Thermal Regime of the Lithosphere across Beardmore Glacier Region, Central Transantarctic Mountains, from Magnetotelluric Measurements"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -84.34835, "title": "Rift Mechanisms and Thermal Regime of the Lithosphere across Beardmore Glacier Region, Central Transantarctic Mountains, from Magnetotelluric Measurements", "uid": "600102", "west": 141.01732}, {"awards": "0542111 Lonsdale, Darcy", "bounds_geometry": ["POINT(-166.287 -76.5799)"], "date_created": "Sat, 01 Jan 2011 00:00:00 GMT", "description": "Recent studies of marine ecosystems show conflicting evidence for trophic cascades, and in particular the relative strength of the crustacean zooplankton-phytoplankton link. The Ross Sea is a natural laboratory for investigating this apparent conflict. It is a site of seasonally high abundances of phytoplankton, characterized by regions of distinct phytoplankton taxa; the southcentral polynya is strongly dominated by the colony-forming prymnesiophyte Phaeocystis antarctica, while coastal regions of this sea are typically dominated by diatoms or flagellate species. Recent studies indicate that, while the south-central polynya exhibits a massive phytoplankton bloom, the poor food quality of P. antarctica for many crustacean zooplankton prevents direct utilization of much of this phytoplankton bloom. Rather, evidence suggests that indirect utilization of this production may be the primary mechanism by which carbon and energy become available to those higher trophic levels. Specifically, we hypothesized that nano- and microzooplankton constitute an important food source for crustacean zooplankton (largely copepods and juvenile euphausiids) during the summer period in the Ross Sea where the phytoplankton assemblage is dominated by the prymnesiophyte. In turn, we also hypothesize that predation by copepods (and other Crustacea) controls and structures the species composition of these protistan assemblages. We occupied stations in the south-central Ross Sea Polynya (RSP) and Terra Nova Bay (TNB) during austral summer to test these hypotheses. We hypothesized that the diatom species that dominate the phytoplankton assemblage in TNB constitute a direct source of nutrition to herbivorous/omnivorous zooplankton (relative to the situation in the south-central RSP). That is, the contribution of heterotrophic protists to crustacean diets will be reduced in TNB. Our research addressed fundamental gaps in our knowledge of food web structure and trophic cascades.", "east": -166.287, "geometry": ["POINT(-166.287 -76.5799)"], "keywords": "Antarctica; Biota; Crustacea; Oceans; Phytoplankton; Ross Sea; Southern Ocean", "locations": "Ross Sea; Antarctica; Southern Ocean", "north": -76.5799, "nsf_funding_programs": null, "persons": "Lonsdale, Darcy", "project_titles": "Collaborative Research: Do Crustacean Zooplankton Play a Pivotal Role in Structuring Heterotrophic Plankton Communities in the Ross Sea?", "projects": [{"proj_uid": "p0000520", "repository": "USAP-DC", "title": "Collaborative Research: Do Crustacean Zooplankton Play a Pivotal Role in Structuring Heterotrophic Plankton Communities in the Ross Sea?"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -76.5799, "title": "Do Crustacean Zooplankton Play a Pivotal Role in Structuring Heterotrophic Plankton Communities in the Ross Sea?", "uid": "600059", "west": -166.287}, {"awards": "0538580 Hemming, Sidney", "bounds_geometry": ["POLYGON((60 -60,72 -60,84 -60,96 -60,108 -60,120 -60,132 -60,144 -60,156 -60,168 -60,180 -60,180 -61,180 -62,180 -63,180 -64,180 -65,180 -66,180 -67,180 -68,180 -69,180 -70,168 -70,156 -70,144 -70,132 -70,120 -70,108 -70,96 -70,84 -70,72 -70,60 -70,60 -69,60 -68,60 -67,60 -66,60 -65,60 -64,60 -63,60 -62,60 -61,60 -60))"], "date_created": "Fri, 01 Jan 2010 00:00:00 GMT", "description": "This project studies sediment from the ocean floor to understand Antarctica\u0027s geologic history. Glacially eroded from the Antarctic continent, these sediments may offer insight into the 99% Antarctica covered by ice. The work\u0027s central focus is determining crust formation ages and thermal histories for three key areas of East Antarctica--Prydz Bay, eastern Weddell Sea, and Wilkes Land--through a combination of petrography, bulk sediment geochemistry and radiogenic isotopes, as well as isotope chronology of individual mineral grains. One specific objective is characterizing the composition of the Gamburtsev Mountains through studies of Eocene fluvial sediments from Prydz Bay. In addition to furthering our understanding of the hidden terrains of Antarctica, these terrigenous sediments will also serve as a natural laboratory to evaluate the effects of continental weathering on the Hf/Nd isotope systematics of seawater. An important broader impact of the project is providing exciting research projects for graduate and postdoctoral students using state of the art techniques in geochemistry.", "east": 180.0, "geometry": ["POINT(120 -65)"], "keywords": "Antarctica; Chemistry:Sediment; Geochemistry; Geochronology; isotope data; Marine Sediments; Oceans; Prydz Bay; Solid Earth; Southern Ocean; Weddell Sea; Wilkes Land", "locations": "Weddell Sea; Prydz Bay; Wilkes Land; Southern Ocean; Antarctica", "north": -60.0, "nsf_funding_programs": null, "persons": "van de Flierdt, Tina; Goldstein, Steven L.; Hemming, Sidney R.", "project_titles": "Antarctica\u0027s Geological History Reflected in Sedimentary Radiogenic Isotopes", "projects": [{"proj_uid": "p0000524", "repository": "USAP-DC", "title": "Antarctica\u0027s Geological History Reflected in Sedimentary Radiogenic Isotopes"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -70.0, "title": "Antarctica\u0027s Geological History Reflected in Sedimentary Radiogenic Isotopes", "uid": "600056", "west": 60.0}, {"awards": "0442857 Baker, Bill", "bounds_geometry": ["POLYGON((-65 -63,-64.8 -63,-64.6 -63,-64.4 -63,-64.2 -63,-64 -63,-63.8 -63,-63.6 -63,-63.4 -63,-63.2 -63,-63 -63,-63 -63.2,-63 -63.4,-63 -63.6,-63 -63.8,-63 -64,-63 -64.2,-63 -64.4,-63 -64.6,-63 -64.8,-63 -65,-63.2 -65,-63.4 -65,-63.6 -65,-63.8 -65,-64 -65,-64.2 -65,-64.4 -65,-64.6 -65,-64.8 -65,-65 -65,-65 -64.8,-65 -64.6,-65 -64.4,-65 -64.2,-65 -64,-65 -63.8,-65 -63.6,-65 -63.4,-65 -63.2,-65 -63))"], "date_created": "Fri, 01 Jan 2010 00:00:00 GMT", "description": "Mesoherbivores, and specifically amphipods, are a conspicuous and dominant component of the macroalgal community in Antarctica. Despite their high abundance, the functional ecology, and particularly the trophic relationships of Antarctic amphipods are poorly understood. This project will evaluate the importance of mesograzers (small invertebrate predators approximately 1 to 25 mm in body length) in western Antarctic Peninsula marine communities. This will be accomplished by examining the role of mesoherbivores in structuring macroalgal communities and by elucidating the ecological interactions of mesograzers with a dominant group of benthic macroinvertebrates, the marine sponges. Moreover, chemical studies will be conducted to gain a more thorough understanding of the chemical defenses that Antarctic Peninsula sponges direct towards crustacean mesograzers. Three sets of questions will be addressed concerning the importance of mesograzers, and amphipods in particular, in nearshore habitats of the western Antarctic Peninsula. First, the hypothesis that mesoherbivory is particularly heavy in western Antarctic Peninsula marine communities and has an important influence on algal community structure will be addressed. Initial studies will document which species of amphipods feed in whole or part on microalgae and macroalgae, the incidence and distribution of filamentous endophytes in dominant macroalgae, comparative night time patterns of amphipod abundances on macrophytes, and the role of chemical mediation in these relationships. Second, the broad hypothesis that mesograzers in general, and amphipods in particular, interact with and prey upon sponges to a greater extent than heretofore recognized in Antarctic communities will be tested. The functional basis of these associations will be considered by examining whether the sponges are used as prey, and if so, whether there is evidence that some sponges produce secondary metabolites that show efficacy against mesograzers such as amphipods. Third, the researchers will test the hypotheses that: 1) Antarctic algae and invertebrates biosynthesize secondary metabolites that deter feeding by amphipod predators; and 2) pigments found in three Antarctic sponges are tryptophan catabolites produced as defenses against crustacean predators that impact molting. Evaluation of these hypotheses will be based on isolation and characterization of the specific anti-feeding metabolites, on biosynthetic studies to establish the metabolic origin of the pigments, and on bioassays to establish the chemical defense roles of both groups of compounds. A variety of educational activities will be a major component of this project. Opportunities will be made to support graduate and undergraduate research, both through NSF programs as well as home university-based programs including a number of funded programs that enhance the representation of minorities in the sciences. Through their proven and highly successful interactive web program, the investigators will continue to involve a large numbers of teachers, K-12 students, and other members of the community at large in their scientific endeavors in Antarctica. Moreover, they will actively participate in outreach efforts by presenting numerous talks on their research to school and community groups.", "east": -63.0, "geometry": ["POINT(-64 -64)"], "keywords": "Antarctica; Biota; Oceans; Southern Ocean", "locations": "Antarctica; Southern Ocean", "north": -63.0, "nsf_funding_programs": null, "persons": "Baker, Bill", "project_titles": "Collaborative Research: The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula; Collaborative Research: The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula - continuing", "projects": [{"proj_uid": "p0010016", "repository": "USAP-DC", "title": "Collaborative Research: The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula - continuing"}, {"proj_uid": "p0000475", "repository": "USAP-DC", "title": "Collaborative Research: The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -65.0, "title": "The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula", "uid": "600047", "west": -65.0}, {"awards": "0442769 McClintock, James", "bounds_geometry": ["POLYGON((-64.15 -64.78,-64.132 -64.78,-64.114 -64.78,-64.096 -64.78,-64.078 -64.78,-64.06 -64.78,-64.042 -64.78,-64.024 -64.78,-64.006 -64.78,-63.988 -64.78,-63.97 -64.78,-63.97 -64.784,-63.97 -64.788,-63.97 -64.792,-63.97 -64.796,-63.97 -64.8,-63.97 -64.804,-63.97 -64.808,-63.97 -64.812,-63.97 -64.816,-63.97 -64.82,-63.988 -64.82,-64.006 -64.82,-64.024 -64.82,-64.042 -64.82,-64.06 -64.82,-64.078 -64.82,-64.096 -64.82,-64.114 -64.82,-64.132 -64.82,-64.15 -64.82,-64.15 -64.816,-64.15 -64.812,-64.15 -64.808,-64.15 -64.804,-64.15 -64.8,-64.15 -64.796,-64.15 -64.792,-64.15 -64.788,-64.15 -64.784,-64.15 -64.78))"], "date_created": "Fri, 01 Jan 2010 00:00:00 GMT", "description": "Mesoherbivores, and specifically amphipods, are a conspicuous and dominant component of the macroalgal community in Antarctica. Despite their high abundance, the functional ecology, and particularly the trophic relationships of Antarctic amphipods are poorly understood. This project will evaluate the importance of mesograzers (small invertebrate predators approximately 1 to 25 mm in body length) in western Antarctic Peninsula marine communities. This will be accomplished by examining the role of mesoherbivores in structuring macroalgal communities and by elucidating the ecological interactions of mesograzers with a dominant group of benthic macroinvertebrates, the marine sponges. Moreover, chemical studies will be conducted to gain a more thorough understanding of the chemical defenses that Antarctic Peninsula sponges direct towards crustacean mesograzers. Three sets of questions will be addressed concerning the importance of mesograzers, and amphipods in particular, in nearshore habitats of the western Antarctic Peninsula. First, the hypothesis that mesoherbivory is particularly heavy in western Antarctic Peninsula marine communities and has an important influence on algal community structure will be addressed. Initial studies will document which species of amphipods feed in whole or part on microalgae and macroalgae, the incidence and distribution of filamentous endophytes in dominant macroalgae, comparative night time patterns of amphipod abundances on macrophytes, and the role of chemical mediation in these relationships. Second, the broad hypothesis that mesograzers in general, and amphipods in particular, interact with and prey upon sponges to a greater extent than heretofore recognized in Antarctic communities will be tested. The functional basis of these associations will be considered by examining whether the sponges are used as prey, and if so, whether there is evidence that some sponges produce secondary metabolites that show efficacy against mesograzers such as amphipods. Third, the researchers will test the hypotheses that: 1) Antarctic algae and invertebrates biosynthesize secondary metabolites that deter feeding by amphipod predators; and 2) pigments found in three Antarctic sponges are tryptophan catabolites produced as defenses against crustacean predators that impact molting. Evaluation of these hypotheses will be based on isolation and characterization of the specific anti-feeding metabolites, on biosynthetic studies to establish the metabolic origin of the pigments, and on bioassays to establish the chemical defense roles of both groups of compounds. A variety of educational activities will be a major component of this project. Opportunities will be made to support graduate and undergraduate research, both through NSF programs as well as home university-based programs including a number of funded programs that enhance the representation of minorities in the sciences. Through their proven and highly successful interactive web program, the investigators will continue to involve a large numbers of teachers, K-12 students, and other members of the community at large in their scientific endeavors in Antarctica. Moreover, they will actively participate in outreach efforts by presenting numerous talks on their research to school and community groups.", "east": -63.97, "geometry": ["POINT(-64.06 -64.8)"], "keywords": "Antarctica; Biota; Oceans; Southern Ocean", "locations": "Antarctica; Southern Ocean", "north": -64.78, "nsf_funding_programs": null, "persons": "McClintock, James; Amsler, Charles", "project_titles": "Collaborative Research: The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula; Collaborative Research: The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula - continuing", "projects": [{"proj_uid": "p0000475", "repository": "USAP-DC", "title": "Collaborative Research: The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula"}, {"proj_uid": "p0010016", "repository": "USAP-DC", "title": "Collaborative Research: The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula - continuing"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -64.82, "title": "The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula", "uid": "600046", "west": -64.15}, {"awards": "0228842 Grew, Edward", "bounds_geometry": ["POLYGON((76 -69.3,76.05 -69.3,76.1 -69.3,76.15 -69.3,76.2 -69.3,76.25 -69.3,76.3 -69.3,76.35 -69.3,76.4 -69.3,76.45 -69.3,76.5 -69.3,76.5 -69.32,76.5 -69.34,76.5 -69.36,76.5 -69.38,76.5 -69.4,76.5 -69.42,76.5 -69.44,76.5 -69.46,76.5 -69.48,76.5 -69.5,76.45 -69.5,76.4 -69.5,76.35 -69.5,76.3 -69.5,76.25 -69.5,76.2 -69.5,76.15 -69.5,76.1 -69.5,76.05 -69.5,76 -69.5,76 -69.48,76 -69.46,76 -69.44,76 -69.42,76 -69.4,76 -69.38,76 -69.36,76 -69.34,76 -69.32,76 -69.3))"], "date_created": "Thu, 01 Jan 2009 00:00:00 GMT", "description": "This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a project to investigate the role and fate of Boron in high-grade metamorphic rocks of the Larsemann Hills region of Antarctica. Trace elements provide valuable information on the changes sedimentary rocks undergo as temperature and pressure increase during burial. One such element, boron, is particularly sensitive to increasing temperature because of its affinity for aqueous fluids, which are lost as rocks are buried. Boron contents of unmetamorphosed pelitic sediments range from 20 to over 200 parts per million, but rarely exceed 5 parts per million in rocks subjected to conditions of the middle and lower crust, that is, temperatures of 700 degrees C or more in the granulite-facies, which is characterized by very low water activities at pressures of 5 to 10 kbar (18-35 km burial). Devolatization reactions with loss of aqueous fluid and partial melting with removal of melt have been cited as primary causes for boron depletion under granulite-facies conditions. Despite the pervasiveness of both these processes, rocks rich in boron are locally found in the granulite-facies, that is, there are mechanisms for retaining boron during the metamorphic process. The Larsemann Hills, Prydz Bay, Antarctica, are a prime example. More than 20 lenses and layered bodies containing four borosilicate mineral species crop out over a 50 square kilometer area, which thus would be well suited for research on boron-rich granulite-facies metamorphic rocks. While most investigators have focused on the causes for loss of boron, this work will investigate how boron is retained during high-grade metamorphism. Field observations and mapping in the Larsemann Hills, chemical analyses of minerals and their host rocks, and microprobe age dating will be used to identify possible precursors and deduce how the precursor materials recrystallized into borosilicate rocks under granulite-facies conditions. \n\nThe working hypothesis is that high initial boron content facilitates retention of boron during metamorphism because above a certain threshold boron content, a mechanism \u0027kicks in\u0027 that facilitates retention of boron in metamorphosed rocks. For example, in a rock with large amounts of the borosilicate tourmaline, such as stratabound tourmalinite, the breakdown of tourmaline to melt could result in the formation of prismatine and grandidierite, two borosilicates found in the Larsemann Hills. This situation is rarely observed in rocks with modest boron content, in which breakdown of tourmaline releases boron into partial melts, which in turn remove boron when they leave the system. Stratabound tourmalinite is associated with manganese-rich quartzite, phosphorus-rich rocks and sulfide concentrations that could be diagnostic for recognizing a tourmalinite protolith in a highly metamorphosed complex where sedimentary features have been destroyed by deformation. Because partial melting plays an important role in the fate of boron during metamorphism, our field and laboratory research will focus on the relationship between the borosilicate units, granite pegmatites and other granitic intrusives. The results of our study will provide information on cycling of boron at deeper levels in the Earth\u0027s crust and on possible sources of boron for granites originating from deep-seated rocks. An undergraduate student will participate in the electron microprobe age-dating of monazite and xenotime as part of a senior project, thereby integrating the proposed research into the educational mission of the University of Maine. In response to a proposal for fieldwork, the Australian Antarctic Division, which maintains Davis station near the Larsemann Hills, has indicated that they will support the Antarctic fieldwork.", "east": 76.5, "geometry": ["POINT(76.25 -69.4)"], "keywords": "Antarctica; Chemistry:Rock; Geochemistry; Geochronology; Solid Earth", "locations": "Antarctica", "north": -69.3, "nsf_funding_programs": null, "persons": "Grew, Edward", "project_titles": "Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust?", "projects": [{"proj_uid": "p0000431", "repository": "USAP-DC", "title": "Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust?"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -69.5, "title": "Boron in Antarctic granulite-facies rocks: under what conditions is boron retained in the middle crust?", "uid": "600030", "west": 76.0}, {"awards": "0536526 Le Masurier, Wesley", "bounds_geometry": ["POLYGON((-136 -73,-133.4 -73,-130.8 -73,-128.2 -73,-125.6 -73,-123 -73,-120.4 -73,-117.8 -73,-115.2 -73,-112.6 -73,-110 -73,-110 -73.425,-110 -73.85,-110 -74.275,-110 -74.7,-110 -75.125,-110 -75.55,-110 -75.975,-110 -76.4,-110 -76.825,-110 -77.25,-112.6 -77.25,-115.2 -77.25,-117.8 -77.25,-120.4 -77.25,-123 -77.25,-125.6 -77.25,-128.2 -77.25,-130.8 -77.25,-133.4 -77.25,-136 -77.25,-136 -76.825,-136 -76.4,-136 -75.975,-136 -75.55,-136 -75.125,-136 -74.7,-136 -74.275,-136 -73.85,-136 -73.425,-136 -73))"], "date_created": "Thu, 01 Jan 2009 00:00:00 GMT", "description": "This project uses geochemical studies to determine the origin of volcanic rocks from Marie Byrd Land (MBL), Antarctica. Surprisingly, adjacent volcanoes in the MBL have dramatically different compositions, ranging from phonolite to trachyte to rhyolite. This diversity offers an opportunity to constrain the processes responsible for generating silica oversaturated and undersaturated magmas in a single geologic setting. Previous work suggests that the most obvious and simplest explanation--crustal contamination--is not a significant factor, and that polybaric fractional crystallization is the major cause. This study evaluates these factors through analyses and interpretation of trace and rare earth element abundances, as well as Sr and Nd isotopic ratios. The broader impacts include outreach programs to the Girl Scouts of America, and dissemination of results through publications and meetings.", "east": -110.0, "geometry": ["POINT(-123 -75.125)"], "keywords": "Antarctica; Chemistry:Rock; Geochemistry; IntraContinental Magmatism; Marie Byrd Land; Solid Earth", "locations": "Marie Byrd Land; Antarctica", "north": -73.0, "nsf_funding_programs": null, "persons": "Le Masurier, Wesley", "project_titles": "Geochemistry and Petrologic Evolution of Felsic Volcanoes in Western Marie Byrd Land, Antarctica", "projects": [{"proj_uid": "p0000534", "repository": "USAP-DC", "title": "Geochemistry and Petrologic Evolution of Felsic Volcanoes in Western Marie Byrd Land, Antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -77.25, "title": "Geochemistry and Petrologic Evolution of Felsic Volcanoes in Western Marie Byrd Land, Antarctica", "uid": "600051", "west": -136.0}]

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