The British Antarctic Survey (BAS) has relied on sledge dogs as the main form of transport for field parties since its predecessor, the Falkland Islands Dependencies Survey (FIDS), imported them in 1945, when it created a permanent presence on the continent. Over the years dogs have been used for extensive work over a very wide area. In 1975 BAS changed its policy with respect to work in the southern Antarctic Peninsula. In future seasons scientists will not winter in this area but will be flown to Adelaide Island and then into the field. They will carry out more detailed scientific work in particular areas of interest. This means that it is no longer practical to maintain huskies on base as they could not be kept fit and well disciplined during the winter for a short summer season. The scientists, similarly, could not be expected to learn to work the dogs efficiently in the time available, and the change in the nature of their work means that they will not move camp so frequently. The dogs, since they must be fed even if they are resting, would be uneconomic in such a situation. Finally, most of the work will be in areas that are thought to be safe so the dogs will not be needed to probe for crevasses. In future seasons BAS will rely on skidoos for field work (Figs 1 and 2).
Three model electron distribution functions representative of the region between the plasmapause and the geostationary orbit are constructed. These models are used to compare numerical solutions of the hot electromagnetic dispersion equation with analytical solutions of the quasielectrostatic dispersion equation, and to compare numerical and analytical solutions of the electrostatic dispersion equation, for whistler mode propagation at wave normal angles θ close to the resonance cone angle θR. It is shown that the quasielectrostatic solutions are a reasonable approximation for all three models when θ θR the approximation only remains good inside the plasmapause for frequencies ω equal to 0.4 times the electron gyrofrequency Ω. For θ > θR the agreement between numerical electromagnetic and electrostatic solutions is good whenωΩ⩽ 0.6. Numerical results show that forωΩ= 0.8the solutions to the quasielectrostatic equation for large refractive index correspond to strongly damped waves for each model.
A quarter of the terrestrial Acari recorded from Antarctica and the sub-Antarctic islands are parasitic haematophages or non-feeding phoretics associated with other larger and more mobile animals, especially sea birds and pterygote insects. Although flying sea birds are effective vectors of zoohoric mites into the region, penguins are not and merely serve as reservoir hosts. Similarly, most of the mites associated with insects were accidentally introduced by man as free-living adults that subsequently utilised a range of alien and indigenous insects as local dispersal mechanisms.
There is increasing evidence supporting rapid trajectories of environmental change in the Antarctic. This study describes preliminary data on soil faunal responses to artificial environmental amelioration obtained using a ‘greenhouse’ methodology, over the first year of a manipulative study of part of the soil ecosystem of Mars Oasis, Alexander Island in the southern Maritime Antarctic. The methodology, which used two types of UV-absorbing perspex cloche, influences a range of environmental variables, the most significant of which in this study are thought to be temperature and UV-radiation. The fauna of this site is dominated by Nematoda. Responses to amelioration included large increases in nematode population densities, particularly those of the microbivorous genus, Plectus, combined with changes in the relative abundance of taxa. These faunal changes are likely to be mediated via the responses of autotrophs to the environmental manipulations.
We determine the physicochemical habitat for microorganisms in subsurface terrestrialice by quantitatively constraining the partitioning of bacteria and fluorescent beads(1–10 m) between the solid ice crystals and the water-filled veins and boundaries aroundindividual ice crystals. We demonstrate experimentally that the partitioning of sphericalparticles within subsurface ice depends strongly on size but is largely independent ofsource particle concentration. Although bacteria are shown consistently to partition to theveins, larger particles, which would include eukaryotic cells, become trapped in the crystalswith little potential for continued metabolism. We also calculate the expected concentrationsof soluble impurities in the veins for typical bulk concentrations found in naturalice. These calculations and scanning electron microscope observations demonstrate a concentratedchemical environment (3.5 M total ions at 10 C) in the veins, where bacteriawere found to reside, with a mixture of impurities that could sustain metabolism. Ourcalculations show that typical bacterial cells in glacial ice would fit within the narrowveins, which are a few micrometers across. These calculations are confirmed by microscopicimages of spherical, 1.9-m-diameter, fluorescent beads and stained bacteria insubsurface veins. Typical bacterial concentrations in clean ice (102–103 cells/mL) wouldresult in concentrations of 106–108 cells/mL of vein fluid, but occupy only a small fractionof the total available vein volume (0.2%). Hence, bacterial populations are not limitedby vein volume, with the bulk of the vein being unoccupied and available to supply energysources and nutrients.
The number of Antarctic fur seals Arctocephalus gazella hauled out at Signy Island in the South Orkneys was monitored annually between 1977 and 2008. Over the study period seal abundance showed a tenfold increase, from a minimum of 1,643 seals in 1978 to a maximum of 21,303 in 1994. The majority of individuals observed were young adult males, likely to be migrants from South Georgia, with small numbers of female seals and only 65 pups recorded during the survey period. Variability in counts showed a similar pattern to Laurie Island, also in the South Orkneys archipelago, suggesting a similar annual immigration of seals to these two islands. The date of first seal arrival was correlated with the date of fast-ice breakout at Factory Cove, Signy Island, and years in which break out was exceptionally late (> 21 December) corresponded with years of reduced seal abundance. While the presence of fast-ice during the early breeding season may currently inhibit the establishment of a major breeding population of fur seals at Signy Island, it is important that routine monitoring should continue, particularly in the light of current patterns of climate warming in the Antarctic.
Locally grounded features in ice shelves, called ice rises and rumples, play a key role buttressing discharge from the Antarctic Ice Sheet and regulating its contribution to sea level. Ice rises typically rise several hundreds of meters above the surrounding ice shelf; shelf flow is diverted around them. On the other hand, shelf ice flows across ice rumples, which typically rise only a few tens of meters above the ice shelf. Ice rises contain rich histories of deglaciation and climate that extend back over timescales ranging from a few millennia to beyond the last glacial maximum. Numerical model results have shown that the buttressing effects of ice rises and rumples are significant, but details of processes and how they evolve remain poorly understood. Fundamental information about the conditions and processes that cause transitions between floating ice shelves, ice rises and ice rumples is needed in order to assess their impact on ice-sheet behavior. Targeted high-resolution observational data are needed to evaluate and improve prognostic numerical models and parameterizations of the effects of small-scale pinning points on grounding-zone dynamics.
Debate continues about the nature of the Cretaceous–Paleogene (K–Pg) mass extinction event. An abrupt crisis triggered by a bolide impact contrasts with ideas of a more gradual extinction involving flood volcanism or climatic changes. Evidence from high latitudes has also been used to suggest that the severity of the extinction decreased from low latitudes towards the poles. Here we present a record of the K–Pg extinction based on extensive assemblages of marine macrofossils (primarily new data from benthic molluscs) from a highly expanded Cretaceous–Paleogene succession: the López de Bertodano Formation of Seymour Island, Antarctica. We show that the extinction was rapid and severe in Antarctica, with no significant biotic decline during the latest Cretaceous, contrary to previous studies. These data are consistent with a catastrophic driver for the extinction, such as bolide impact, rather than a significant contribution from Deccan Traps volcanism during the late Maastrichtian.
Seabirds breeding on the Antarctic continent must cope with extreme changes in sea ice cover and day length throughout the year. Adélie penguins are expected to adjust their migratory movements and diving activity to seasonal changes in foraging conditions, but their winter diving activities have not been examined previously. Here, we tracked 18 and 5 Adélie penguins by using geolocators with and without depth sensors, from a colony in East Antarctica over 2 winter seasons. After breeding, all but one penguin migrated westward from March to April, then moved northward from May to August as the sea ice edge extended to the north, then moved southeastward, returning towards the breeding colony. Migratory movements followed sea ice movements and the seasonal extension in this region, which is influenced by the west-flowing Antarctic Slope Current and wind. Penguins dived deeper during winter, reaching a maximum depth of 129 m. The birds dived mostly between civil dawn and dusk, and tended to stay on ice overnight. Diving effort (total time spent underwater per day) did not decline with sea ice concentrations, suggesting that penguins found open water to dive even with >90% sea ice cover. Diving effort was lowest around the winter solstice, but was relatively high before and after the annual moult, and also before the start of breeding when birds presumably needed to accumulate body reserves. Our results highlight how the migratory movement and winter diving activity of Adélie penguins are closely associated with the seasonal polar environment.
Written by Utah Valley has won four of its past five conference games, including the last two on the road. The Wolverines had a 34-21 rebounding advantage against Chicago State and a 14-2 advantage in second-chance points. Utah Valley led 23-8 in points off the bench. Chicago State has lost 10 in a row and has one win over a Division I team this season. January 26, 2019 /Sports News – Local Lowell, Toolson lead Utah Valley past Chicago State 74-60 Cameron Bowles and Anthony Harris scored 17 points apiece and Rob Shaw added 10 points for the Cougars (3-18, 0-6). Tags: Jake Toolson/UVU Wolverines Basketball/WAC/Wyatt Lowell Baylee Steele added 12 points and TJ Washington scored 10 for the Wolverines (15-7, 4-3 Western Athletic Conference). FacebookTwitterLinkedInEmailCHICAGO (AP) — Wyatt Lowell had 15 points with nine rebounds off the bench, Jake Toolson scored a game-high 18 points and Utah Valley defeated Chicago State 74-60 on Saturday. Associated Press