Relative sea-level history from the Lambert Glacier region, East Antarctica, and its relation to deglaciation and Holocene glacier readvance

first_imgWe present a relative sea-level (RSL) history, constrained by AMS radiocarbon-dated marine–freshwater transitions in isolation basins from a site adjacent to the Lambert Glacier, East Antarctica. The RSL data suggest an initial ice retreat between c. 15,370 and 12,660 cal yr B.P.. Within this period, meltwater pulse IA (mwp IA, between c. 14,600–14,200 and 14,100–13,700 cal yr B.P.) occurred; an exceptionally large ice melting event, inferred from far-field sea-level records. The RSL curve shows a pronounced highstand of approximately 8 m between c. 7570–7270 and 7250–6950 cal yr B.P. that is consistent with the timing of the RSL highstand in the nearby Vestfold Hills. This is followed by a fall in RSL to the present. In contrast to previous findings, the isolation of the lakes in the Larsemann Hills postdates the isolation of lakes with similar sill heights in the Vestfold Hills. An increase in RSL fall during the late Holocene may record a decline in the rate of isostatic uplift in the Larsemann Hills between c. 7250–6950 and 2847–2509 cal yr B.P., that occurred in response to a documented mid-Holocene glacier readvance followed by a late-Holocene retreat.last_img read more

Environmental constraints on life histories in Antarctic ecosystems: tempos, timings and predictability

first_imgKnowledge of Antarctic biotas and environments has increased dramatically in recent years. There has also beena rapid increase in the use of novel technologies. Despite this, some fundamental aspects of environmental controlthat structure physiological, ecological and life-history traits in Antarctic organisms have received little attention.Possibly the most important of these is the timing and availability of resources, and the way in which this dictatesthe tempo or pace of life. The clearest view of this effect comes from comparisons of species living in differenthabitats. Here, we (i) show that the timing and extent of resource availability, from nutrients to colonisable space,differ across Antarctic marine, intertidal and terrestrial habitats, and (ii) illustrate that these differences affect therate at which organisms function. Consequently, there are many dramatic biological differences between organismsthat live as little as 10 m apart, but have gaping voids between them ecologically.Identifying the effects of environmental timing and predictability requires detailed analysis in a wide context,where Antarctic terrestrial and marine ecosystems are at one extreme of the continuum of available environmentsfor many characteristics including temperature, ice cover and seasonality. Anthropocentrically, Antarctica isharsh and as might be expected terrestrial animal and plant diversity and biomass are restricted. By contrast,Antarctic marine biotas are rich and diverse, and several phyla are represented at levels greater than globalaverages. There has been much debate on the relative importance of various physical factors that structure thecharacteristics of Antarctic biotas. This is especially so for temperature and seasonality, and their effects onphysiology, life history and biodiversity. More recently, habitat age and persistence through previous ice maximahave been identified as key factors dictating biodiversity and endemism. Modern molecular methods have alsorecently been incorporated into many traditional areas of polar biology. Environmental predictability dictatesmany of the biological characters seen in all of these areas of Antarctic research.last_img read more

Active layer thermal regime under different vegetation conditions in permafrost areas. A case study at Signy Island (Maritime Antarctica)

first_imgClimate change is now evident also in Antarctica, with impacts both on the abiotic and the biotic components of ecosystems, particularly on permafrost, active layer thickness, vegetation, and soil properties. Permafrost ecosystems are recognized to be sensitive to the influences of the changing climate, which may activate, through complex mechanisms, both positive and negative feedbacks relating to CO2 fluxes. For this reason we analysed, through a data set collected over a complete year, the thermal regime of the active layer at four sites with different vegetation (bare ground, lichen vegetation with Usnea aurantiaco-atra, moss vegetation with Sanionia uncinata, grass vegetation with Deschampsia antarctica) but with similar topographic and geomorphological conditions at Signy Island (Maritime Antarctica). Except for the Deschampsia site, the other three sites are the same formerly studied by Chambers in the 1960s. The three sites show significant differences of the mean annual ground surface temperature (MAGST), ranging from -1.9 (Usnea) to -2.6 degrees C (Sanionia). Despite the clear differences in MAGST at the investigated sites, the mean annual ground temperature at 30 cm is virtually identical. Our results confirm that mosses play an important role in cooling the ground. The results of our study allow us to suggest also that the thawing degree days should be used instead of the growing degree days as a more suitable measure of the favourable conditions for the growth of the Antarctic cryptogam vegetation. Comparing our data with those of Chambers [Chambers, M.J.G., 1966b. Investigations on patterned ground at Signy Island, South Orkney Islands: II. Temperature regimes in the active layer. British Antarctic Survey Bulletin, 10: 71-83.], we can stress that the thermal conditions favourable to the frost heave is actually even more limited in depth (30 cm vs 40 cm in Chambers). Moreover, the freeze-thaw days near the surface appeared to be more frequent in the vegetated sites than in the bare ground.last_img read more

Non-stormtime injection of energetic particles into the slot-region between Earth’s inner and outer electron radiation belts as observed by STSAT-1 and NOAA-POES

first_imgThe slot-region between Earth’s inner and outer electron radiation belts was observed on 24 February 2004 by the satellite STSAT-1 to be populated by quasi-trapped electrons of energy 100-400 keV. This injection lasted for several hours and took place during a non-stormtime substorm. This appears to be the first observation of a slot-region electron injection that did not occur during a geomagnetic storm. We also report multi-instrument observations of this event from NOAA-POES and CPMN magnetic observatories, and we consider physical mechanisms that may account for the phenomenon. Citation: Park, J., et al. (2010), Non-stormtime injection of energetic particles into the slot-region between Earth’s inner and outer electron radiation belts as observed by STSAT-1 and NOAA-POESlast_img read more

The ice thickness distribution of Flask Glacier, Antarctic Peninsula, determined by combining radio-echo soundings, surface velocity data and flow modelling

first_imgAn interpolated bedrock topography is presented for Flask Glacier, one of the tributaries of the remnant part of the Larsen B ice shelf, Antarctic Peninsula. The ice thickness distribution is derived by combining direct but sparse measurements from airborne radio-echo soundings with indirect estimates obtained from ice-flow modelling. The ice-flow model is applied to a series of transverse profiles, and a first estimate of the bedrock is iteratively adjusted until agreement between modelled and measured surface velocities is achieved. The adjusted bedrock is then used to reinterpret the radio-echo soundings, and the recovered information used to further improve the estimate of the bedrock itself. The ice flux along the glacier center line provides an additional and independent constraint on the ice thickness. The resulting bedrock topography reveals a glacier bed situated mainly below sea level with sections having retrograde slope. The total ice volume of 120±15 km3 for the considered area of 215 km2 corresponds to an average ice thickness of 560±70 m.last_img read more

Emigration in emperor penguins: implications for interpretation of long-term studies

first_imgSite fidelity is an important evolutionary trait to understand, as misinterpretation of philopatric behavior could lead to confusion over the key drivers of population dynamics and the environmental or anthropogenic factors influencing populations. Our objective was to explore the hypothesis that emperor penguins are strictly philopatric using satellite imagery, counts from aerial photography, and literature reports on emperor penguin distributions. We found six instances over three years in which emperor penguins did not return to the same location to breed. We also report on one newly-discovered colony on the Antarctic Peninsula that may represent the relocation of penguins from the Dion Islands, recently confirmed as having been abandoned. Using evidence from aerial surveys and the historical literature, we suggest that emigration may have been partly responsible for the population decline at Pointe Géologie during the 1970s. Our study is the first to use remote sensing imagery to suggest that emperor penguins can and do move between, and establish new, colonies. Metapopulation dynamics of emperor penguins have not been previously considered and represent an exciting, and important, avenue for future research. Life history plasticity is increasingly being recognized as an important aspect of climate change adaptation, and in this regard our study offers new insight for the long-term future of emperor penguins.last_img read more

Grayson Murphy Leads Utah Track & Field Into NCAA Regionals

first_img FacebookTwitterLinkedInEmailSACRAMENTO, Calif.-University of Utah senior All-American Grayson Murphy headlines the Utes’ women’s track and field team’s contingent to Sacramento State University this week for the NCAA West regionals. (Thursday-Saturday).Murphy, the star senior out of Salt Lake City, will be joined by fellow senior Jessica Sams, junior Caitlin Faust and sophomore Sarah Newton.Utes head coach Kyle Kepler says his hope is that he can get his kids to qualify for the NCAA Championship meet June 6-9 at Hayward Field in Eugene, Ore.Murphy, a four-time All-American, will be competing in her best event, the 3000-meter steeplechase, as well as the 5000 and 10000-meter runs. She represents the Utes’ best chance to have a representation at Hayward Field.Murphy’s best time in the 3000-meter steeplechase this season is 9:51.36, which is the Pac-12’s best time of the season and fifth-best in the NCAA (which at the Division I level consists of 351 schools).With this time, Murphy also broke her own school record in the event. She will compete in the 3000-meter steeplechase Friday at roughly 10:00 pm MDT.Faust, a junior out of Stone Mountain, Ga. and Newton, a sophomore out of Holladay, Utah, will each be competing in the 800-meter run Thursday around 9:35 pm MDT. This duo continually rises up the Utes’ record books as Faust is currently the sixth-best 800-meter runner in school history and Newton is close behind in eighth-place all-time in school annals.Sams, an Ogden, Utah product, will compete in the 5000-meter run which occurs at roughly 9:45 pm MDT on Saturday.All athletes in these respective events at this regional who place in the top 12 will advance to Hayward Field. Tags: Caitlin Faust/Grayson Murphy/Jessica Sams/Kyle Kepler/Sarah Newton/Utah Women’s Track Written by May 22, 2018 /Sports News – Local Grayson Murphy Leads Utah Track & Field Into NCAA Regionals Brad Jameslast_img read more

SUU’s Evans/Wright Named As Big Sky Scholar-Athletes of the Year

first_imgJuly 5, 2018 /Sports News – Local SUU’s Evans/Wright Named As Big Sky Scholar-Athletes of the Year Tags: Big Sky Conference/MaCail Evans/Matthew Wright/Scholar-Athletes Written by Brad James FacebookTwitterLinkedInEmailOGDEN, Utah-Southern Utah University’s MaCail Evans and Matthew Wright have been named as the 2018 Big Sky scholar-athletes of the year Thursday.To qualify for this award, student-athletes must maintain a GPA of 3.2, be a member of their graduating class and/or have completed their last year of intercollegiate athletic eligibility, have completed at least two years of intercollegiate competition and be a letter-winner in their respective sport.Evans, a former Thunderbirds volleyball standout and a native of Minersville, Utah, appeared in all 110 sets for Southern Utah and was second on the squad with 244 kills.Additionally, she added 136 total blocks during the 2017 campaign and is sixth in program history in total blocks.Wright, a native of Enoch, Utah, represented the Thunderbirds on the national stage several times in 2016 and 2017 as he ran in the NCAA Cross Country national championship meet on two occasions.He also ran at the NCAA West prelims during the 2017 outdoor season and also competed at the NCAA Mountain Region Cross Country championships twice as well.Wright leaves SUU as a six-time medalist at various Big Sky Conference Track & Field championship meets.last_img read more

Smurthwaite Promoted To Director of Development at Utah State

first_img FacebookTwitterLinkedInEmailLOGAN, Utah-Friday, Utah State assistant vice president and deputy athletics director for external affairs Coleman Barnes announced the promotion of KC Smurthwaite to the director of development for Aggies Unlimited.Prior to his promotion, Smurthwaite spent the two previous years as a major gifts officer. In his new role, Smurthwaite will oversee the day-to-day operations of the athletics’ development office.This includes annual giving, stewardship and special events while also serving on the External Leadership Team.Prior to this position at Utah State, Smurthwaite spent two seasons as an assistant with the USU softball team.He worked directly with the outfielders while also assisting with recruiting.He came to Utah State in 2014 and served as the softball team’s manager and assistant in the athletics’ compliance office.As a team manager, Smurthwaite helped by throwing batting practice, helping to organize team travel, assisting in day-to-day duties and working with the infielders and slappers.The Meridian, Idaho native has also served as an assistant baseball coach and recruiting coordinator at USU-Eastern Utah of Price.He originally signed with the Eagles as a baseball player. However, injuries cut his playing career short and he began to fill a variety of athletic administrative roles at USU-Eastern.He is a 2013 graduate of Southern Utah University in 2013, earning a bachelor’s in communication studies and later earned a master’s degree from Utah State in physical and sport education in 2015. Brad James Tags: Aggies Unlimited/Coleman Barnes/KC Smurthwaite/Southern Utah University/USU-Eastern Utah Baseball/Utah State Softball Written by July 20, 2018 /Sports News – Local Smurthwaite Promoted To Director of Development at Utah Statelast_img read more

Keanna Williams Wins Region 14 Title

first_img Written by Brad James Tags: Juab Girls Tennis/Keanna Williams/Liberty Park/Region 14/Union/Wasatch Academy September 22, 2018 /Sports News – Local Keanna Williams Wins Region 14 Title FacebookTwitterLinkedInEmailSALT LAKE CITY-Friday, Juab girls’ tennis fell to Wasatch Academy in the Region 14 final at Liberty Park in Salt Lake City. However, one Wasp was successful as Keanna Williams took the Region 14 title, prevailing 5-7, 6-3, 6-3 over competition from Union. The Wasps will compete at the 3-A state championship tournament Friday and Saturday 28 and 29 at Liberty Park.last_img read more