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Sample records for antarctic regions

  1. First geomagnetic measurements in the Antarctic region

    Science.gov (United States)

    Raspopov, O. M.; Demina, I. M.; Meshcheryakov, V. V.

    2014-05-01

    Based on data from literature and archival sources, we have further processed and analyzed the results of geomagnetic measurements made during the 1772-1775 Second World Expedition by James Cook and the 1819-1821 overseas Antarctic Expedition by Russian mariners Bellingshausen and Lazarev. Comparison with the GUFM historical model showed that there are systematic differences in the spatial structure of both the declination and its secular variation. The results obtained can serve as a basis for the construction of regional models of the geomagnetic field for the Antarctic region.

  2. Perspectives on the economic history of the Antarctic region

    OpenAIRE

    Basberg, Bjørn L.

    2005-01-01

    This paper starts out by indicating how the economic history of the Antarctic could be conceptualized, given the peculiarities of the continent and the region (no permanent population, no sovereignty in a traditional sense, extreme remoteness, rigorous climate etc.). Second, it describes the main industries throughout Antarctic history. Third, it examines the quantitative data available on economic activity in the region, suggests how we should proceed to analyse the economic a...

  3. Recent Rapid Regional Climate Warming on the Antarctic Peninsula

    Science.gov (United States)

    Vaughan, D. G.; Marshall, G. J.; Connolley, W. M.; Parkinson, C.; Mulvaney, R.; Hodgson, D. A.; King, J. C.; Pudsey, C. J.; Turner, J.

    2002-12-01

    The Intergovernmental Panel on Climate Change (IPCC) confirmed that global warming was 0.6 ñ 0.2 degrees C during the 20th Century and cited increases in greenhouse gases as a likely contributor. But this average conceals the complexity of observed climate change, which is seasonally biased, decadally variable and geographically patchy. In particular, over the last 50 years three high-latitude areas have undergone recent rapid regional (RRR) warming ? substantially more rapid than the global mean. We discuss the spatial and temporal significance of RRR warming in one area, the Antarctic Peninsula. New analyses of station records show no ubiquitous polar amplification of global warming but significant RRR warming on the Antarctic Peninsula. We investigate the likelihood that this could be amplification of a global warming, and use climate-proxy data to indicate that this RRR warming on the Antarctic Peninsula is unprecedented over the last two millennia and unlikely to be a natural mode of variability. We can show a strong connection between RRR warming and reduced sea-ice duration in an area on the west of the Antarctic Peninsula, but here we cannot yet distinguish cause and effect. Thus for the present we cannot determine which process causes the RRR warming, and until the mechanism initiating and sustaining it is understood, and is convincingly reproduced in climate models, we lack a sound basis for predicting climate change in this region over the coming century.

  4. Development of a regional glycerol dialkyl glycerol tetraether (GDGT)-temperature calibration for Antarctic and sub-Antarctic lakes

    Science.gov (United States)

    Foster, Louise C.; Pearson, Emma J.; Juggins, Steve; Hodgson, Dominic A.; Saunders, Krystyna M.; Verleyen, Elie; Roberts, Stephen J.

    2016-01-01

    A regional network of quantitative reconstructions of past climate variability is required to test climate models. In recent studies, temperature calibration models based on the relative abundances of sedimentary glycerol dialkyl glycerol tetraethers (GDGTs) have enabled past temperature reconstructions in both marine and terrestrial environments. Nevertheless, to date these methods have not been widely applied in high latitude environments due to poor performance of the GDGT-temperature calibrations at lower temperatures. To address this we studied 32 lakes from Antarctica, the sub-Antarctic Islands and Southern Chile to: 1) quantify their GDGT composition and investigate the environmental controls on GDGT composition; and 2) develop a GDGT-temperature calibration model for inferring past temperatures from Antarctic and sub-Antarctic lakes. GDGTs were found in all 32 lakes studied and in 31 lakes branched GDGTs (brGDGTs) were the dominant compounds. Statistical analyses of brGDGT composition in relation to temperature, pH, conductivity and water depth showed that the composition of brGDGTs is strongly correlated with mean summer air temperature (MSAT). This enabled the development of the first regional brGDGT-temperature calibration for use in Antarctic and sub-Antarctic lakes using four brGDGT compounds (GDGT-Ib, GDGT-II, GDGT-III and GDGT-IIIb). A key discovery was that GDGT-IIIb is of particular importance in cold lacustrine environments. The addition of this compound significantly improved the model's performance from r2 = 0.67, RMSEP-LOO (leave-one-out) = 2.23 °C, RMSEP-H (h-block) = 2.37 °C when applying the re-calibrated global GDGT-temperature calibration to our Antarctic dataset to r2 = 0.83, RMSEP-LOO = 1.68 °C, RMSEP-H = 1.65 °C for our new Antarctic calibration. This shows that Antarctic and sub-Antarctic, and possibly other high latitude, palaeotemperature reconstructions should be based on a regional GDGT-temperature calibration where specific

  5. New and interesting small-celled naviculoid diatoms (Bacillariophyta) from the Maritime Antarctic Region

    Czech Academy of Sciences Publication Activity Database

    Van de Vijver, B.; Kopalová, Kateřina; Zidarova, R.; Cox, E. J.

    2013-01-01

    Roč. 97, 1-2 (2013), s. 189-208. ISSN 0029-5035 Institutional support: RVO:67985939 Keywords : Bacillariophyta * Diatoms * Maritime Antarctic Region Subject RIV: EF - Botanics Impact factor: 0.989, year: 2013

  6. Environmental radioactivity at the Peruvian Scientific Station Machu Picchu 1999 - 2000 Antarctic region

    International Nuclear Information System (INIS)

    The Peruvian Institute of Nuclear Energy (IPEN) initiated the Environmental Radioactivity studies in the Antarctic Region in 1996. The objective of this research was to determine the levels of natural and artificial radioactivity achieving the evaluation of the radiological status in the antarctic region. Samples of brown algae (phaeophyta), lichens, moss, gramineous, soil, marine sediment, sea water and air were collected in the surrounding area of the Machu Picchu Scientific Station. This study shows the results corresponding to the 1999-2000 period

  7. Regional Changes in the Sea Ice Cover and Ice Production in the Antarctic

    Science.gov (United States)

    Comiso, Josefino C.

    2011-01-01

    Coastal polynyas around the Antarctic continent have been regarded as sea ice factories because of high ice production rates in these regions. The observation of a positive trend in the extent of Antarctic sea ice during the satellite era has been intriguing in light of the observed rapid decline of the ice extent in the Arctic. The results of analysis of the time series of passive microwave data indicate large regional variability with the trends being strongly positive in the Ross Sea, strongly negative in the Bellingshausen/Amundsen Seas and close to zero in the other regions. The atmospheric circulation in the Antarctic is controlled mainly by the Southern Annular Mode (SAM) and the marginal ice zone around the continent shows an alternating pattern of advance and retreat suggesting the presence of a propagating wave (called Antarctic Circumpolar Wave) around the circumpolar region. The results of analysis of the passive microwave data suggest that the positive trend in the Antarctic sea ice cover could be caused primarily by enhanced ice production in the Ross Sea that may be associated with more persistent and larger coastal polynyas in the region. Over the Ross Sea shelf, analysis of sea ice drift data from 1992 to 2008 yields a positive rate-of-increase in the net ice export of about 30,000 km2 per year. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 km3/year, which is almost identical, within error bars, to our estimate of the trend in ice production. In addition to the possibility of changes in SAM, modeling studies have also indicated that the ozone hole may have a role in that it causes the deepening of the lows in the western Antarctic region thereby causing strong winds to occur offthe Ross-ice shelf.

  8. Temperature variation and its driving forces over the Antarctic coastal regions in the past 250 years

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By comparing the oxygen isotopic temperatures recorded by many shallow ice cores fromthe coastal regions of Antarctica, this paper presents the special characteristics of the temperaturevariations over the Antarctic coastal regions in the past 50 years, 150 years and 250 years. In thepast 50 years, the isotopic temperatures recorded in the ice cores over different sites on the Antarcticcoastal regions differ greatly. For instance, although increasing isotopic temperatures have beenreported for many sites studied, many sites show decreasing trends, the regional regularity intemperature variations is still insignificant. In the past 150 years, the isotopic temperature trends inthe coastal regions of Antarctica show an alternate-distributing pattern. In the past 250 years, all theice cores from the coastal regions of Antarctica have recorded the so-called Little Ice Age (LIA). Theabove-mentioned spatial characteristics of the temperature variations over the Antarctic coastalregions are likely to reflect the impacts of the unique Southern Hemisphere atmospheric circulation,the Antarctic Circumpolar Wave (ACW) and the special terrain (such as the large drainage basins) onthe coastal regions of Antarctica. Furthermore, the impacting intensity of the unique SouthernHemisphere atmospheric circulation, the Antarctic Circumpolar Wave and the special terrain differs interms of the temporal scale of the temperature change.

  9. Monitoring snow-cover area change in Antarctic coastline region using MODIS product data

    Institute of Scientific and Technical Information of China (English)

    Chen Jing; Li Rendong; Ye Ming; Lu Yang

    2009-01-01

    Based on MODIS snow products, this article studied the changes of snow cover area during 2003-2006 along the coastline of the Antarctic, and 18 typical regions were chosen for further analysis. The result showed that the change of snow cover area was in a fluctuant downward trend as a whole, and more fluctuated obviously in warm season than in cold season. In temporal scale: for the season cycle, the snow cover extent increased rapidly in cold season (Apr-Oct), while the performance in warm season (Nov-Mar) was not exactly the same during the four years, the snow cover extent decreased in the first and then increased in 2004 and 2006, however, increased firstly and then decreased but reduced as a whole in 2005, for the inter-annual cycle, snow cover extent was the largest in 2003, but reached to the lowest level in 2004, and then increased gradually in 2005 and 2006, whereas, it declined with fluctuant as a whole. In spatial scale, changes mainly centralized along the coastline, moreover, it was more remarkable in the West Antarctic than in the East Antarctic, especially in the Antarctic Peninsula region.

  10. Coreless Winter Characteristics Observed with Global Positioning System Receivers over Antarctic and Arctic Regions

    Directory of Open Access Journals (Sweden)

    Wayan Suparta

    2012-01-01

    Full Text Available Problem statement: The most recent warming trends occurred during the winter in Polar Regions had been attracted many researchers to study its impacts, which might affect the sensitivity of climate prediction in both regions, as well as on a global basis. Approach: The aims of this study were to observe the characteristics of coreless winter events using the GPS meteorology such as the Zenith Tropospheric Delay (ZTD, Precipitable Water Vapor (PWV, the surface meteorology and the solar radiation measurements. The periods of observations were within two years which from January 2008 to December 2009 for Antarctic and from July 2008 to June 2010 for the Arctic. Results: The occurrence of coreless winter had clearly detected in June and January for Antarctic and Arctic, respectively. During the winter period, PWV and ZTD, temperature and relative humidity variations in both regions demonstrate a significant unusual warming peak than with the surface pressure. During this event, the increasing of 1°C of temperature showed that the PWV in Arctic was observed twice larger compared to the Antarctic. Conclusion: The increased PWV during winter suggest that the coreless winters characteristic is signified when advection between the warm or cold air masses over the region tend to increase the formation of cyclonic activity that causes increasing in surface temperature.

  11. Antarctic 20th Century Accumulation Changes Based on Regional Climate Model Simulations

    OpenAIRE

    Dörthe Handorf; Annette Rinke; Ksenia Glushak; Klaus Dethloff

    2010-01-01

    The regional climate model HIRHAM has been applied to Antarctica driven at the lateral and lower boundaries by European Reanalysis data ERA-40 for the period 1958–1998. Simulations over 4 decades, carried out with a horizontal resolution of 50 km, deliver a realistic simulation of the Antarctic atmospheric circulation, synoptic-scale pressure systems, and the spatial distribution of precipitation minus sublimation (P-E) structures. The simulated P-E pattern is in qualitative agreement with gl...

  12. Mapping and interpretation of satellite magnetic anomalies from POGO data over the Antarctic region

    Directory of Open Access Journals (Sweden)

    P. T. Taylor

    1999-06-01

    Full Text Available A satellite magnetic anomaly map made using the POGO magnetic field data is compared to three maps made using Magsat data. A total of 14 anomalies with magnitudes greater than 3 nT can be identified in all four of the maps poleward of 60°S latitude. Forward models of the Antarctic continental and oceanic lithosphere are produced which use magnetic crustal thickness based on seismic and heat flow data, and which also use the distribution of the Cretaceous Quiet Zone from marine geophysics. These simple models can explain significant parts of eight of the 14 identified anomalies. The remaining anomalies may be caused by lateral variations of magnetization, inadequate models of the magnetic crustal thickness, or remanent magnetizations in directions other than the present field. In addition, contamination of the magnetic anomaly maps by fields of time-varying external origin (and their corresponding internal parts is still a significant problem in the Antarctic region.

  13. Four Achnanthidium species (Bacillariophyta formerly identified as Achnanthidium minutissimum from the Antarctic Region

    Directory of Open Access Journals (Sweden)

    Bart Van de Vijver

    2014-04-01

    Full Text Available Four taxa belonging to the complex of species around Achnanthidium minutissimum were found during the ongoing taxonomic revision of the Antarctic freshwater and limno-terrestrial diatom flora. Two taxa were previously described as Achnanthidium lailae and A. sieminskae. Two others were formerly identified as A. minutissimum but detailed light and scanning electron microscopical observations revealed sufficient morphological differences compared to the type of A. minutissimum, to justify their separation and description as new taxa: Achnanthidium indistinctum and A. maritimo-antarcticum. The morphology and ecology of all four taxa are discussed comparing the species with morphologically similar taxa. The biogeographical consequences of the splitting of the former A. minutissimum complex in the Antarctic Region are discussed.

  14. Winter/summer transition in the Antarctic mesopause region

    Science.gov (United States)

    Lübken, F.-J.; Höffner, J.; Viehl, T. P.; Becker, E.; Latteck, R.; Kaifler, B.; Murphy, D. J.; Morris, R. J.

    2015-12-01

    A new set of temperature data with unprecedented resolution and accuracy has been obtained from Fe lidar measurements at Davis, Antarctica (69°S). Here we concentrate on the months of the winter/summer transition (November to February) where we have collected a total of 1305 h of observations in the three seasons 2010/2011, 2011/2012, and 2012/2013. The temporal development of temperatures around the mesopause in 2012/2013 is rather similar to the Northern Hemisphere (NH), whereas the other seasons are significantly different, exhibiting, e.g., an unusual higher and colder mesopause around solstice (elevated summer mesopause). During this exceptional period mean daily mesopause heights and temperatures are approximately 92.0 ± 0.5 km and 125 K, respectively. The seasonal variation of temperatures in the mesopause region is closely related to the circulation in the stratosphere which exhibits an early (late) vortex breakdown in 2012/2013 (2010/2011). The situation is more complicated in 2011/2012. The early (late) transition in the mesopause region is accompanied by an early (late) appearance of polar mesosphere summer echoes. Zonal winds as measured by an MF radar also show systematic differences with westward winds reaching up to very high altitudes (nearly 100 km) for the late transition in 2010/2011 and to more common heights (˜90 km) for the early transition in 2012/2013. A mesopause being higher and colder compared to the NH (as occasionally observed at Davis) cannot be achieved by standard models. More sophisticated characterization of gravity wave forcing might be required.

  15. Chemistry of snow and lake water in Antarctic region

    Indian Academy of Sciences (India)

    Kaushar Ali; Sunil Sonbawane; D M Chate; Devendraa Siingh; P S P Rao; P D Safai; K B Budhavant

    2010-12-01

    Surface snow and lake water samples were collected at different locations around Indian station at Antarctica, Maitri, during December 2004-March 2005 and December 2006-March 2007.Samples were analyzed for major chemical ions. It is found that average pH value of snow is 6.1. Average pH value of lake water with low chemical content is 6.2 and of lake water with high chemical content is 6.5.The Na+ and Cl− are the most abundantly occurring ions at Antarctica. Considerable amount of SO$^{2-}_{4}$ is also found in the surface snow and the lake water which is attributed to the oxidation of DMS produced by marine phytoplankton.Neutralization of acidic components of snow is mainly done by NH$^{+}_{4}$ and Mg2+. The Mg2+, Ca2+ and K+ are nearly equally effective in neutralizing the acidic components in lake water.The NH$^{+}_{4}$ and SO$^{2-}_{4}$ occur over the Antarctica region mostly in the form of (NH4)2SO4.

  16. Antarctic 20th Century Accumulation Changes Based on Regional Climate Model Simulations

    Directory of Open Access Journals (Sweden)

    Klaus Dethloff

    2010-01-01

    investigated on the basis of ERA-40 data and HIRHAM simulations. It is shown that the regional accumulation changes are largely driven by changes in the transient activity around the Antarctic coasts due to the varying AAO phases. During positive AAO, more transient pressure systems travelling towards the continent, and Western Antarctica and parts of South-Eastern Antarctica gain more precipitation and mass. Over central Antarctica the prevailing anticyclone causes a strengthening of polar desertification connected with a reduced surface mass balance in the northern part of East Antarctica.

  17. Historical whaling records reveal major regional retreat of Antarctic sea ice

    Science.gov (United States)

    Cotté, Cédric; Guinet, Christophe

    2007-02-01

    Several studies have provided evidence of a reduction of the Antarctic sea ice extent. However, these studies were conducted either at a global scale or at a regional scale, and possible inter-regional differences were not analysed. Using the long-term whaling database we investigated circum-Antarctic changes in summer sea ice extent from 1931 to 1987. Accounting for bias inherent in the whaling method, this analysis provides new insight into the historical ice edge reconstruction and inter-regional differences. We highlight a reduction of the sea ice extent occurring in the 1960s, mainly in the Weddell sector where the change ranged from 3° to 7.9° latitude through summer. Although the whaling method may not be appropriate for detecting fine-scale change, these results provide evidence for a heterogeneous circumpolar change of the sea ice extent. The shift is temporally and spatially consistent with other environmental changes detected in the Weddell sector and also with a shift in the Southern Hemisphere annular mode. The large reduction of the sea ice extent has probably influenced the ecosystem of the Weddell Sea, particularly the krill biomass.

  18. Ozone Loss in the Antarctic Vortex Boundary Region from in situ Observations with the Geophysica Aircraft

    Science.gov (United States)

    Ivanova, E.; Volk, C. M.; Riediger, O.; Strunk, M.; Schmidt, U.; Ulanovsky, A.; Ravegnani, F.; Redaelli, G.

    2003-04-01

    We analyse the distribution of ozone depletion in the Antarctic vortex edge region from in situ measurements taken from the Russian high-altitude aircraft M-55 "Geophysica" during the APE-GAIA campaign (Airborne Polar Experiment - Geophysica Aircraft In Antarctica) based out of Ushuaia, Argentina (54° S) in September and October 1999. The University of Frankfurt's High Altitude Gas Analyzer (HAGAR) provided in situ measurements of N2O, CFC-12, CFC-11, halon-1211 every 90 s, SF6 every 45 s, and CO2 every 10 s. Ozone was measured at high resolution by the Fast Ozone Analyzer (FOZAN). During 5 southbound flights toward the Antarctic vortex the Geophysica penetrated the vortex edge at various potential temperatures between 380 K and 480 K and performed dives inside the vortex yielding vertical profiles in one case down to the tropopause. The amount of lost ozone in the measured air has been estimated from the deviations from the compact extra-vortex O3-N2O relationship. While nearly complete ozone loss is found only in air clearly inside the vortex, ozone loss up to 60% is routinely found in a transition region extending 5° northward from the edge delineated by sharp meridional tracer gradients. We investigate whether this transition region lies indeed outside the vortex by applying alternative methods for defining the vortex edge, including potential vorticity and a new method using the observed relation of N2O with potential temperature (Greenblatt et al., J. Geophys. Res., 2002). We also examine the correlations between O3, CO2, and N2O to investigate the possibility that the decreased ozone within the transition region is caused by outward mixing from the vortex core.

  19. Surface ozone observations during voyages to the Arctic and Antarctic regions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Surface ozone concentration and UV-B data between 75°N and 70°S were obtained aboard the Chinese polar scientific vessel "Xue-long" (Snow-Dragon) during the first voyage to the Arctic and the 16th to the Antarctic in 1999-2000. Analysis of these data presents that variations of the surface ozone concentration have small amplitude during voyages except the mid-latitude in the Northern Hemisphere. As a whole, average surface ozone concentration in the Northern Hemisphere is higher than that in the Southern, and high value occurred when the ship sailed close to the continents. The average diurnal variations of the surface ozone in the Northern Hemisphere are also higher compared to the southern counterparts, and high diurnal variations were found at low latitudes, and relative low level in the polar region.

  20. Four new monoraphid diatom species (Bacillariophyta, Achnanthaceae from the Maritime Antarctic Region

    Directory of Open Access Journals (Sweden)

    Kateřina Kopalová

    2016-07-01

    Full Text Available Four monoraphid taxa belonging to the genera Achnanthes, Psammothidium and Planothidium were found during the ongoing taxonomic revision of the freshwater and limno-terrestrial diatoms of the Maritime Antarctic region. The present paper describes these four taxa as new based on detailed light and scanning electron microscopy observations: Achnanthes kohleriana Kopalová, Zidarova & Van de Vijver sp. nov., Planothidium wetzelectorianum Kopalová, Zidarova & Van de Vijver sp. nov., Psammothidium confusoneglectum Kopalová, Zidarova & Van de Vijver sp. nov. and Psammothidium superpapilio Kopalová, Zidarova & Van de Vijver sp. nov. The morphology and ecology of all four taxa are discussed and the species are compared with morphologically similar taxa.

  1. Usnea antarctica, an important Antarctic lichen, is vulnerable to aspects of regional environmental change

    OpenAIRE

    Bokhorst, S.; P. Convey; Huiskes, A.H.L.; Aerts, R

    2016-01-01

    Studies of cryptogam responses to climate change in the polar regions are scarce because these slow-growing organisms require long-term monitoring studies. Here, we analyse the response of a lichen and moss community to 10 years of passive environmental manipulation using open-top chambers (OTCs) in the maritime Antarctic region. Cover of the dominant lichen Usnea antarctica declined by 71 % in the OTCs. However, less dominant lichen species showed no significant responses except for an incre...

  2. Phytoplankton abundance and community structure in the Antarctic polar frontal region during austral summer of 2009

    Institute of Scientific and Technical Information of China (English)

    SHRAMIK Patil; RAHUL Mohan; SUHAS Shetye; SAHINA Gazi

    2013-01-01

    The Antarctic polar front region in the Southern Ocean is known to be most productive.We studied the phytoplankton community structure in the Indian sector at this frontal location during late austral summer (February,2009) onboard R/V Akademic Boris Petrov.We used the phytoplankton and microheterotrophs abundance,as also the associated physico-chemical parameters to explain the low phytoplankton abundance in the study region.This study emphasizes the shift of phytoplankton,from large (>10 μm) to small (<10 μm) size.The phytoplankton abundance appears to be controlled by physical parameters and by nutrient concentrations and also by the microheterotrophs (ciliates and dinoflagellates) which exert a strong grazing pressure.This probably reduces small (<10 μm) and large (>10 μm)phytoplankton abundance during the late austral summer.This study highlights the highly productive polar front nevertheless becomes a region of low phytoplankton abundance,due to community shifts towards pico-phytoplankton (<10 μm) during late austral summer.

  3. Yeasts from sub-Antarctic region: biodiversity, enzymatic activities and their potential as oleaginous microorganisms.

    Science.gov (United States)

    Martinez, A; Cavello, I; Garmendia, G; Rufo, C; Cavalitto, S; Vero, S

    2016-09-01

    Various microbial groups are well known to produce a range of extracellular enzymes and other secondary metabolites. However, the occurrence and importance of investment in such activities have received relatively limited attention in studies of Antarctic soil microbiota. Sixty-one yeasts strains were isolated from King George Island, Antarctica which were characterized physiologically and identified at the molecular level using the D1/D2 region of rDNA. Fifty-eight yeasts (belonging to the genera Cryptococcus, Leucosporidiella, Rhodotorula, Guehomyces, Candida, Metschnikowia and Debaryomyces) were screened for extracellular amylolytic, proteolytic, esterasic, pectinolytic, inulolytic xylanolytic and cellulolytic activities at low and moderate temperatures. Esterase activity was the most common enzymatic activity expressed by the yeast isolates regardless the assay temperature and inulinase was the second most common enzymatic activity. No cellulolytic activity was detected. One yeast identified as Guehomyces pullulans (8E) showed significant activity across six of seven enzymes types tested. Twenty-eight yeast isolates were classified as oleaginous, being the isolate 8E the strain that accumulated the highest levels of saponifiable lipids (42 %). PMID:27469174

  4. New and interesting species of the genus Muelleria (Bacillariophyta) from the Antarctic region and South Africa

    Science.gov (United States)

    Van De Vijver, B.; Mataloni, G.; Stanish, L.; Spaulding, S.A.

    2010-01-01

    During a survey of the terrestrial diatom flora of some sub-Antarctic islands in the southern Indian and Atlantic Oceans and of the Antarctic continent, more than 15 taxa belonging to the genus Muelleria were observed. Nine of these taxa are described as new species using light and scanning electron microscopy. Comments are made on their systematic position and how they are distinguished from other species in the genus. Additionally, two previously unrecognized taxa within the genus were discovered in samples from South Africa. One of these, Muelleria taylorii Van de Vijver & Cocquyt sp. nov., is new to science; the other, Muelleria vandermerwei (Cholnoky) Van de Vijver & Cocquyt nov. comb., had been included in the genus Diploneis. The large number of new Muelleria taxa on the (sub)-Antarctic locations is not surprising. Species in Muelleria occur rarely in collections; in many habitats, it is unusual to find more than 1-2 valves in any slide preparation. As a result, records are scarce. The practice of "force-fitting" (shoehorning) specimens into descriptions from common taxonomic keys (and species drift) results in European species, such as M. gibbula and M. linearis, being applied to Antarctic forms in ecological studies. Finally, the typical terrestrial habitats of soils, mosses and ephemeral water bodies of most of these taxa have been poorly studied in the past.

  5. Stable water isotopes of precipitation and firn cores from the northern Antarctic Peninsula region as a proxy for climate reconstruction

    Directory of Open Access Journals (Sweden)

    F. Fernandoy

    2012-03-01

    Full Text Available In order to investigate the climate variability in the northern Antarctic Peninsula region, this paper focuses on the relationship between stable isotope content of precipitation and firn, and main meteorological variables (air temperature, relative humidity, sea surface temperature, and sea ice extent. Between 2008 and 2010, we collected precipitation samples and retrieved firn cores from several key sites in this region. We conclude that the deuterium excess oscillation represents a robust indicator of the meteorological variability on a seasonal to sub-seasonal scale. Low absolute deuterium excess values and the synchronous variation of both deuterium excess and air temperature imply that the evaporation of moisture occurs in the adjacent Southern Ocean. The δ18O-air temperature relationship is complicated and significant only at a (multiseasonal scale. Backward trajectory calculations show that air-parcels arriving at the region during precipitation events predominantly originate at the South Pacific Ocean and Bellingshausen Sea. These investigations will be used as a calibration for ongoing and future research in the area, suggesting that appropriate locations for future ice core research are located above 600 m a.s.l. We selected the Plateau Laclavere, Antarctic Peninsula as the most promising site for a deeper drilling campaign.

  6. Future surface mass balance of the Antarctic ice sheet and its influence on sea level change, simulated by a regional atmospheric climate model

    NARCIS (Netherlands)

    Ligtenberg, S.R.M.; van de Berg, W.J.; van den Broeke, M.R.; Rae, J.G.L.; van Meijgaard, E.

    2013-01-01

    A regional atmospheric climate model with multi-layer snow module (RACMO2) is forced at the lateral boundaries by global climate model (GCM) data to assess the future climate and surface mass balance (SMB) of the Antarctic ice sheet (AIS). Two different GCMs (ECHAM5 until 2100 and HadCM3 until 2200)

  7. Antarctic Tourism and Maritime Heritage

    OpenAIRE

    Basberg, Bjørn L.

    2010-01-01

    Maritime activities in the Antarctic region date back to the eighteenth century. They evolved from exploration and discoveries to commercial enterprises, especially sealing, whaling and fishing. Antarctic tourism is a much more recent phenomenon, developing mainly from the 1950s and 1960s. Today over 40,000 tourists visit the Antarctic annually, most of them on cruise ships. This essay reviews the historical development of this tourism. The focus is on how maritime heritage has been treated a...

  8. Determination of the crust thickness in the active margin of the Antarctic region; Determinacao da estrutura crustal na margem ativa da regiao antartica

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Luiz Carlos; Gamboa, Luiz Antonio Pierantoni [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Lagemar; Gomes, Benedito Souza [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    1997-07-01

    Seismic multichannel, gravity and magnetometry measurements were carried out in the region of West coast of the Antarctic Peninsula, Bransfield Strait, South Shetland Islands and South Shetland Trench, by Brazilian Antarctic Program during the summers of 1987 and 1988. The present work, using a continue seismic and gravity and gravity data profile crossing the area, intends to present a two-dimensional model of the crust thickness in this region. By this model, the Moho discontinuity would lie at a depth of 14.5 km below the axis of the Bransfield trough. This anomalous behaviour in addition to compressional processes identified in the accretionary prism and trench, was interpreted as an evidence of the continued opening of the Bransfield basin. (author)

  9. Diversity and extracellular enzymatic activities of yeasts isolated from King George Island, the sub-Antarctic region

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    Carrasco Mario

    2012-11-01

    Full Text Available Abstract Background Antarctica has been successfully colonized by microorganisms despite presenting adverse conditions for life such as low temperatures, high solar radiation, low nutrient availability and dryness. Although these “cold-loving” microorganisms are recognized as primarily responsible for nutrient and organic matter recycling/mineralization, the yeasts, in particular, remain poorly characterized and understood. The aim of this work was to study the yeast microbiota in soil and water samples collected on King George Island. Results A high number of yeast isolates was obtained from 34 soil and 14 water samples. Molecular analyses based on rDNA sequences revealed 22 yeast species belonging to 12 genera, with Mrakia and Cryptococcus genera containing the highest species diversity. The species Sporidiobolus salmonicolor was by far the most ubiquitous, being identified in 24 isolates from 13 different samples. Most of the yeasts were psychrotolerant and ranged widely in their ability to assimilate carbon sources (consuming from 1 to 27 of the 29 carbon sources tested. All species displayed at least 1 of the 8 extracellular enzyme activities tested. Lipase, amylase and esterase activity dominated, while chitinase and xylanase were less common. Two yeasts identified as Leuconeurospora sp. and Dioszegia fristingensis displayed 6 enzyme activities. Conclusions A high diversity of yeasts was isolated in this work including undescribed species and species not previously isolated from the Antarctic region, including Wickerhamomyces anomalus, which has not been isolated from cold regions in general. The diversity of extracellular enzyme activities, and hence the variety of compounds that the yeasts may degrade or transform, suggests an important nutrient recycling role of microorganisms in this region. These yeasts are of potential use in industrial applications requiring high enzyme activities at low temperatures.

  10. Evaluation of the CMIP5 models in the aim of regional modelling of the Antarctic surface mass balance

    Science.gov (United States)

    Agosta, C.; Fettweis, X.; Datta, R.

    2015-12-01

    The surface mass balance (SMB) of the Antarctic Ice Sheet cannot be reliably deduced from global climate models (GCMs), both because their spatial resolution is insufficient and because their physics are not adapted for cold and snow-covered regions. By contrast, regional climate models (RCMs) adapted for polar regions can physically and dynamically downscale SMB components over the ice sheet using large-scale forcing at their boundaries. Polar-oriented RCMs require appropriate GCM fields for forcing because the response of the cryosphere to a warming climate is dependent on its initial state and is not linear with respect to temperature increase. In this context, we evaluate the current climate in 41 climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) data set over Antarctica by focusing on forcing fields which may have the greatest impact on SMB components simulated by RCMs. Our inter-comparison includes six reanalyses, among which ERA-Interim reanalysis is chosen as a reference over 1979-2014. Model efficiency is assessed taking into account the multi-decadal variability of the fields over the 1850-1980 period. We show that fewer than 10 CMIP5 models show reasonable biases compared to ERA-Interim, among which ACCESS1-3 is the most pertinent choice for forcing RCMs over Antarctica, followed by ACCESS1-0, CESM1-BGC, CESM1-CAM5, NorESM1-M, CCSM4 and EC-EARTH. Finally, climate change over the Southern Ocean in CMIP5 is less sensitive to the global warming signal than it is to the present-day simulated sea-ice extent and to the feedback between sea-ice decrease and air temperature increase around Antarctica.

  11. Biodiversity and biogeography of Antarctic and sub-Antarctic mollusca

    Science.gov (United States)

    Linse, Katrin; Griffiths, Huw J.; Barnes, David K. A.; Clarke, Andrew

    2006-04-01

    For many decades molluscan data have been critical to the establishment of the concept of a global-scale increase in species richness from the poles to the equator. Low polar diversity is key to this latitudinal cline in diversity. Here we investigate richness patterns in the two largest classes of molluscs at both local and regional scales throughout the Southern Ocean. We show that biodiversity is very patchy in the Southern Ocean (at the 1000-km scale) and test the validity of historical biogeographic sub-regions and provinces. We used multivariate analysis of biodiversity patterns at species, genus and family levels to define richness hotspots within the Southern Ocean and transition areas. This process identified the following distinct sub-regions in the Southern Ocean: Antarctic Peninsula, Weddell Sea, East Antarctic—Dronning Maud Land, East Antarctic—Enderby Land, East Antarctic—Wilkes Land, Ross Sea, and the independent Scotia arc and sub Antarctic islands. Patterns of endemism were very different between the bivalves and gastropods. On the basis of distributional ranges and radiation centres of evolutionarily successful families and genera we define three biogeographic provinces in the Southern Ocean: (1) the continental high Antarctic province excluding the Antarctic Peninsula, (2) the Scotia Sea province including the Antarctic Peninsula, and (3) the sub Antarctic province comprising the islands in the vicinity of the Antarctic Circumpolar Current.

  12. Assemblages of micronektonic fishes and invertebrates in a gradient of regional warming along the Western Antarctic Peninsula

    Science.gov (United States)

    Parker, Melanie L.; Fraser, William R.; Ashford, Julian; Patarnello, Tomaso; Zane, Lorenzo; Torres, Joseph J.

    2015-12-01

    Micronektonic fishes and invertebrates were sampled with 32 midwater trawls at nine sites along the Western Antarctic Peninsula (WAP) in the austral fall (March-April) of 2010. Study sites were located within four hypothesized hydrographic regions: near Joinville Island in Region I, at Croker Passage, near Anvers Island, and near Renaud Island in Region II, within Marguerite Bay and the Marguerite Trough in Region III, and near Charcot Island in Region IV. A total of 62 taxa representing 12 taxonomic groups of pelagic invertebrates and 9 families of fish were captured, but assemblages were dominated by only a few species. The most numerically abundant taxa were the euphausiids, Thysanoessa macrura, Euphausia superba, and E. crystallorophias, combining to contribute nearly 79% of the total catch. Biomass dominants included E. superba, which contributed more than 44% of the total catch, the notothenioid Pleuragramma antarctica, and the salp, Salpa thompsoni. A comparison of total catches among sites revealed that the largest volumetric abundances and biomasses were captured at the Marguerite Bay site. Cluster analysis of abundance data identified distinct multispecies assemblages at Joinville Island in Region I, Croker Passage in Region II, Marguerite Bay in Region III, and Charcot Island in Region IV. A fifth distinct assemblage included samples from sites near Anvers and Renaud Island in Region II, and from the Marguerite Trough in Region III. Assemblages at Joinville Island and Croker Passage were both dominated by E. superba and S. thompsoni, but hydrographic conditions at Joinville Island favored a neritic assemblage, underscored by substantial numbers of P. antarctica. The assemblage at Croker Passage was more oceanic in nature with major inputs from the myctophid, Electrona antarctica and the hyperiid amphipod, Themisto gaudichaudii. Marguerite Bay and Charcot Island were well-mixed assemblages with strong representation by both neritic and oceanic fauna. The

  13. Validation of the Antarctic Snow Accumulation and Ice Discharge Basal Stress Boundary in the South Eastern Region of the Ross Ice Shelf, Antarctica

    Science.gov (United States)

    Nelson, C. B.; King, K.

    2015-12-01

    The largest ice shelf in Antarctic, Ross Ice Shelf, was investigated over the years of (1970-2015). Near the basal stress boundary between the ice shelf and the West Antarctic ice sheet, ice velocity ranges from a few meters per year to several hundred meters per year in ice streams. Most of the drainage from West Antarctica into the Ross Ice Shelf flows down two major ice streams, each of which discharges more than 20 km3 of ice each year. Along with velocity changes, the warmest water below parts of the Ross Ice Shelf resides in the lowest portion of the water column because of its high salinity. Vertical mixing caused by tidal stirring can thus induce ablation by lifting the warm water into contact with the ice shelf. This process can cause melting over a period of time and eventually cause breakup of ice shelf. With changes occurring over many years a validation is needed for the Antarctic Snow Accumulation and Ice Discharge (ASAID) basal stress boundary created in 2003. After the 2002 Larsen B Ice Shelf disintegration, nearby glaciers in the Antarctic Peninsula accelerated up to eight times their original speed over the next 18 months. Similar losses of ice tongues in Greenland have caused speed-ups of two to three times the flow rates in just one year. Rapid changes occurring in regions surrounding Antarctica are causing concern in the polar science community to research changes occurring in coastal zones over time. During the research, the team completed study on the Ross Ice Shelf located on the south western coast of the Antarctic. The study included a validation of the ABSB vs. the natural basal stress boundary (NBSB) along the Ross Ice Shelf. The ASAID BSB was created in 2003 by a team of researchers headed by National Aeronautics and Space Administration Goddard Space Flight Center (NASA GSFC), with an aim of studying coastal deviations as it pertains to the mass balance of the entire continent. The point data file was aimed at creating a replica of the

  14. Antarctic tourism and the maritime heritage

    OpenAIRE

    Basberg, Bjørn L.

    2008-01-01

    Maritime activity in the Antarctic region goes back to the 18th Century. It evolved from exploration and discoveries to commercial activities, especially sealing and whaling. Antarctic tourism is a more recent phenomenon, developing gradually from the 1960s. Today, more than 20.000 tourists visit the Antarctic annually – mostly on cruise ships. The paper reviews the historical development of these activities. The main focus is on how the maritime heritage has been dealt with an...

  15. Environmental radioactivity in the antarctic station

    International Nuclear Information System (INIS)

    Study about environmental radioactivity in the Peruvian antarctic station Machu Pichu they were carried out during the last three periods to the southern summer. The objective of the project it is to evaluate environmental component in order to elaborate a study it base on the levels background radioactivity and artificial in the antarctic region

  16. Environmental contamination in Antarctic ecosystems.

    Science.gov (United States)

    Bargagli, R

    2008-08-01

    Although the remote continent of Antarctica is perceived as the symbol of the last great wilderness, the human presence in the Southern Ocean and the continent began in the early 1900s for hunting, fishing and exploration, and many invasive plant and animal species have been deliberately introduced in several sub-Antarctic islands. Over the last 50 years, the development of research and tourism have locally affected terrestrial and marine coastal ecosystems through fuel combustion (for transportation and energy production), accidental oil spills, waste incineration and sewage. Although natural "barriers" such as oceanic and atmospheric circulation protect Antarctica from lower latitude water and air masses, available data on concentrations of metals, pesticides and other persistent pollutants in air, snow, mosses, lichens and marine organisms show that most persistent contaminants in the Antarctic environment are transported from other continents in the Southern Hemisphere. At present, levels of most contaminants in Antarctic organisms are lower than those in related species from other remote regions, except for the natural accumulation of Cd and Hg in several marine organisms and especially in albatrosses and petrels. The concentrations of organic pollutants in the eggs of an opportunistic top predator such as the south polar skua are close to those that may cause adverse health effects. Population growth and industrial development in several countries of the Southern Hemisphere are changing the global pattern of persistent anthropogenic contaminants and new classes of chemicals have already been detected in the Antarctic environment. Although the Protocol on Environmental Protection to the Antarctic Treaty provides strict guidelines for the protection of the Antarctic environment and establishes obligations for all human activity in the continent and the Southern Ocean, global warming, population growth and industrial development in countries of the Southern

  17. Antarctic ice-mass balance 2002 to 2011: regional re-analysis of GRACE satellite gravimetry measurements with improved estimate of glacial-isostatic adjustment

    Directory of Open Access Journals (Sweden)

    I. Sasgen

    2012-09-01

    Full Text Available We present regional-scale mass balances for 25 drainage basins of the Antarctic Ice Sheet (AIS from satellite observations of the Gravity and Climate Experiment (GRACE for the years 2002–2011. Satellite gravimetry estimates of the AIS mass balance are strongly influenced by mass movement in the Earth interior caused by ice advance and retreat during the last glacial cycle. Here, we develop an improved glacial-isostatic adjustment (GIA estimate for Antarctica using newly available GPS uplift rates, allowing us to more accurately separate GIA-induced trends in the GRACE gravity fields from those caused by current imbalances of the AIS. Our revised GIA estimate is considerably lower than previous predictions, yielding an (upper estimate of apparent mass change of 48 ± 18 Gt yr−1. Therefore, our AIS mass balance of −103 ± 23 Gt yr−1 is considerably less negative than previous GRACE estimates. The Northern Antarctic Peninsula and the Amundsen Sea Sector exhibit the largest mass loss (−25 ± 6 Gt yr−1 and −126 ± 11 Gt yr−1, respectively. In contrast, East Antarctica exhibits a slightly positive mass balance (19 ± 16 Gt yr−1, which is, however, mostly the consequence of compensating mass anomalies in Dronning Maud and Enderby Land (positive and Wilkes and George V Land (negative due to interannual accumulation variations. In total, 7% of the area constitute more than half of the AIS imbalance (53%, contributing −151 ± 9 Gt yr−1 to global mean sea-level change. Most of this imbalance is caused by long-term ice-dynamic speed up expected to prevail in the future.

  18. Traveling reference NILU-UV at the Antarctic region: solar UV comparisons at Ushuaia and Marambio in 2002

    Science.gov (United States)

    Meinander, O.; Lakkala, K.; Redondas, A.; Torres, C.; Cuevas, E.; Deferrari, G.; Koskela, T.; Taalas, P.

    2003-04-01

    The Antarctic UV-monitoring network established by INM in collaboration with FMI, DNA-IAA (Dirección Nacional del Antártico - Instituto Antártico Argentino, Argentina), and CADIC consists of NILU-UV instruments at Belgrano, Marambio and Ushuaia. The NILU-UV multichannel radiometer measures UV radiation at 5 channels, with centre wavelengths at 302, 312, 320, 340 and 380 nm with a bandwidth of about 10 nm FWHM. The quality assurance of the NILU-UV radiometers at Marambio and Ushuaia is based on lamp tests and a traveling reference NILU-UV. Since 1999, the reference travels between the two sites during the sunny time period of the year (between October and May). After one-week measurements at one site, the reference travels to the next site, until two to three solar comparisons are performed at both sites. Lamp tests are made before and after each solar comparison to study the stability of the traveling reference. At the end of the seasonal measurement period, the reference returns to FMI for maintenance and calibrations. In this presentation, the comparison procedure together with latest results, including CIE doserates, will be described.

  19. Surface influence on the marine and coastal Antarctic atmosphere

    OpenAIRE

    Valkonen, Teresa

    2013-01-01

    The Antarctic region plays an important role in the global climate system, and it contributes to the future of global climate through changes in regional factors, such as sea ice, atmospheric circulation patterns and moisture distribution. The aim of this thesis is to improve the understanding of the influence of the Earth surface on the marine and coastal Antarctic atmosphere. The thesis outlines the characteristics of typical phenomena of the Antarctic environment both near the surface and ...

  20. 南极地区大陆架划界引发的法律制度碰撞%CONFLICTS OF LEGAL SYSTEMS INDUCED BY THE DELIMITATION OF THE CONTINENTAL SHELF IN THE ANTARCTIC REGION

    Institute of Scientific and Technical Information of China (English)

    朱瑛; 薛桂芳; 李金蓉

    2011-01-01

    自《南极条约》1961年生效以来,南极地区一直处于以《南极条约》为核心的南极条约体系的约束之下.1982年《联合国海洋法公约》(以下简称《公约》)建立了大陆架制度,要求沿海国应在批准《公约》生效10年内完成200海里以外大陆架外部界限的划定①.1994年《公约》生效后,澳大利亚、挪威、阿根廷和英国在提交各国200海里以外大陆架外部界限划界案时,先后对60°S以南地区的外大陆架提出主张要求.通过解读南极洲领土主张国提交的外大陆架划界案和有关大陆架外部界限的初步信息,跟踪研究大陆架界限委员会审议的有关南极地区的划界案案例,分析沿海国在南极地区的大陆架划界主张的法律依据,进而深入剖析南极条约体系和《公约》两种法律制度在南极地区的矛盾与冲突,并探讨南极地区法律制度的发展走向.%The Antarctic has been under the restriction of Antarctic Treaty System, which includes Antarctic Treaty as its core agreement and other related agreements, since Antarctic Treaty took effect in 1961. Nevertheless, the 1982 U-nited Nations Convention on the Law of Sea (UNCLOS, hereafter referred to as the Convention) established the legal regime for the continental shelf and requested a study into the coastal state of the shelf to complete the delineation of the outer limits of the shelf beyond 200 nautical miles within 10 years of the ratification of the convention. Since the Convention entered into force in 1994, Australia, Norway, Argentina and the United Kingdom have successively and individually claimed their sovereign rights over the continental shelves in the south of 60°S, namely the Antarctic region. With such background, the paper assesses the continental-shelf submissions and preliminary information provided by seven countries claiming territorial sovereignty or sovereign rights to the Antarctic region, and reviews the

  1. Antarctic snow and global climate

    International Nuclear Information System (INIS)

    Global circulation models (GCM) indicate that global warming will be most pronounced at polar regions and high latitudes, causing concern about the stability of the Antarctic ice cap. A project entitled the Seasonal Snow in Antarctica examined the properties of the near surface snow to determine the current conditions that influence snow cover development. The goal was to assess the response of the snow cover in Queen Maud Land (QML) to an increased atmospheric carbon dioxide content. The Antarctic snow cover in QML was examined as part of the FINNARP expeditions in 1999 and 2000 which examined the processes that influence the snow cover. Its energy and mass balance were also assessed by examining the near surface snow strata in shallow (1-2 m) pits and by taking measurements of environmental variables. This made it possible to determine if the glacier is in danger of melting at this northerly location in the Antarctic. The study also made it possible to determine which variables need to change and by how much, for significant melting to occur. It was shown that the Antarctic anticyclone creates particular conditions that protect the snow cover from melting. The anticyclone brings dry air from the stratosphere during most of the year and is exempt from the water vapour feedback. It was concluded that even a doubling of atmospheric carbon dioxide will not produce major snow melt runoff. 8 refs

  2. MAGNETIC ANOMALIES OF PRECAMBRIAN TERRANES OF THE EAST ANTARCTIC SHIELD COASTAL REGION (20°E-50°E)

    OpenAIRE

    ノギ, ヨシフミ; シブヤ, カズオ; Alexander V., GOLYNSKY; Valery N., MASOLOV; Yoshifumi, NOGI; Kazuo, SHIBUYA; Chris, TARLOWSKY; Peter, WELLMAN

    1996-01-01

    Extensive regional magnetic survey flights with a line-spacing of about 20km were conducted by Polar Marine Geological Research Expedition (PMGRE) in 1972,1986,1988 and 1990 over the 20°E-50°E coastal region of East Antarctica. The flights total more than 34000 line-km of total magnetic intensity data acquired along north-south trending profiles. Magnetic anomaly maps compiled from digital data provide a synoptic view of major magnetic anomalies and the corresponding tectonic/geologic feature...

  3. On the Atmospheric Correction of Antarctic Airborne Hyperspectral Data

    OpenAIRE

    Martin Black; Andrew Fleming; Teal Riley; Graham Ferrier; Peter Fretwell; John McFee; Stephen Achal; Alejandra Umana Diaz

    2014-01-01

    The first airborne hyperspectral campaign in the Antarctic Peninsula region was carried out by the British Antarctic Survey and partners in February 2011. This paper presents an insight into the applicability of currently available radiative transfer modelling and atmospheric correction techniques for processing airborne hyperspectral data in this unique coastal Antarctic environment. Results from the Atmospheric and Topographic Correction version 4 (ATCOR-4) package reveal absolute reflectan...

  4. Antarctic research today

    International Nuclear Information System (INIS)

    With the appetite for living and dead natural resources, the political and economical interest concerning the Antarctic increases throughout the world. There are three interrelated main subjects accounting for the international interest: The shelf tectonic puzzle of the original continent of Gondwana, where the Antarctic is situated in the centre, between Australia, South Africa and South America, and the hopes concerning the existence of mineral resources under the ice of the Antarctic are based thereon. The Antarctic forms the biggest unified living space of the world. (orig.)

  5. Antarctic Astrobiology

    Science.gov (United States)

    McKay, Christopher P.

    2003-01-01

    Stars may be cold and dry today but there is compelling evidence that earlier in its history Mars did have liquid water. This evidence comes from the images taken from orbital spacecraft. The dry valleys of Antarctica comprise the largest ice-free region on that continent. The valleys are a cold desert environment with mean annual temperatures of -20 C. The lakes in the dry valleys of Antarctica provide an example of the physical processes that can maintain large bodies of liquid water under mean annual temperatures well below freezing. Biologically these lakes are also important analogs because of the plankton and benthic communities of microorganisms that thrive there. Life could have existed in lakes on Mars an ecological similar conditions.

  6. Controls and variability of solute and sedimentary fluxes in Antarctic and sub-Antarctic Environments

    Science.gov (United States)

    Zwolinski, Zbigniew

    2015-04-01

    . Solute and sediment transport in the streams of analyzed environments are constrained by the relatively short water runoff season that typically lasts from a few weeks to maximum of four months during the austral summer, for Antarctic and sub-Antarctic regions respectively. Because of high intensity of mechanical and chemical weathering processes solute and sediment transport are rather high within Antarctic environments. Weathering rates on slopes and magnitude of fluvial transport in relatively short streams control the intensity of denudational processes. Both mechanical and chemical denudation varies highly through sub-Antarctic and Antarctic environments. To generate accurate predictions of fluvial and denudational processes we must fully understand the actual geoecological processes, which in some places are under rapid change, e.g., the Antarctic Peninsula and sub-Antarctic islands.

  7. Climate Change Influences on Antarctic Bird Populations

    Science.gov (United States)

    Korczak-Abshire, Małgorzata

    2010-01-01

    Rapid changes in the major environmental variables like: temperature, wind and precipitation have occurred in the Antarctic region during the last 50 years. In this very sensitive region, even small changes can potentially lead to major environmental perturbations. Then the climate change poses a new challenge to the survival of Antarctic wildlife. As important bioindicators of changes in the ecosystem seabirds and their response to the climate perturbations have been recorded. Atmospheric warming and consequent changes in sea ice conditions have been hypothesized to differentially affect predator populations due to different predator life-history strategies and substantially altered krill recruitment dynamics.

  8. Antarctic Miocene Climate

    Science.gov (United States)

    Ashworth, A. C.; Lewis, A. R.

    2013-12-01

    significantly colder and drier conditions that resulted in the extinction of the upland biota and a shift in glacial regimes from wet to cold-based. Paleontological and geochemical evidence from the deep marine record supports a major climatic event at this time. Based on pollen from the SHALDRIL cores a tundra biota survived until c. 12.8 Ma on the islands of the Antarctic Peninsula (65°S). Recently, sparse angiosperm pollen of chenopods or similar taxa, has been reported from deposits in the Prince Charles mountains (70°S) with a biostratigraphic age of Mid- to Late Miocene (12-9 Ma) making it possible that remnants of a tundra vegetation continued to exist on the edges of the continent after it had become extinct on the islands of the Antarctic Peninsula. Evidence for Pliocene warmth in the Ross Sea from thick diatomite sequence in ANDRILL cores is so far unsupported by terrestrial paleontological evidence. Pliocene wood-like structures reported from a DVDP core are interpreted as the remains of in situ shrubs but the evidence is unconvincing. Pliocene warmth in the Ross sea region, unaccompanied by an unambiguous terrestrial response can be explained in one of two ways: 1. Pliocene MSTs remained below the 3-4°C threshold needed to support shrub or herb tundra, or 2. Pliocene MSTs were warm enough but terrestrial taxa were unavailable because of extinction. Research supported by NSF 0739693,0947821.

  9. How much snow falls on the Antarctic ice sheet?

    Directory of Open Access Journals (Sweden)

    C. Palerme

    2014-02-01

    Full Text Available Climate models predict Antarctic precipitation to increase during the 21st century, but their present day Antarctic precipitation differs. A fully model-independent climatology of the Antarctic precipitation characteristics, such as snowfall rates and frequency, is needed to assess the models, but was not available so far. Satellite observation of precipitation by active spaceborne sensors has been possible in the polar regions since the launch of CloudSat in 2006. Here we use CloudSat products to build the first multi-year model-independent climatology of Antarctic precipitation. The mean snowfall rate from August 2006 to April 2011 is 171 mm yr−1 over the Antarctic ice sheet north of 82° S. The ECMWF ERA Interim dataset agrees well with the new satellite climatology.

  10. Meteorological observatory for Antarctic data collection

    International Nuclear Information System (INIS)

    In the last years, a great number of automatic weather stations was installed in Antarctica, with the aim to examine closely the weather and climate of this region and to improve the coverage of measuring points on the Antarctic surface. In 1987 the Italian Antarctic Project started to set up a meteorological network, in an area not completely covered by other countries. Some of the activities performed by the meteorological observatory, concerning technical functions such as maintenance of the AWS's and the execution of radio soundings, or relating to scientific purposes such as validation and elaboration of collected data, are exposed. Finally, some climatological considerations on the thermal behaviour of the Antarctic troposphere such as 'coreless winter', and on the wind field, including katabatic flows in North Victoria Land are described

  11. A method for assessing the physical recovery of Antarctic desert pavements following human-induced disturbances: a case study in the Ross Sea region of Antarctica.

    Science.gov (United States)

    O'Neill, Tanya A; Balks, Megan R; López-Martínez, Jerónimo; McWhirter, Judi L

    2012-12-15

    With increasing visitor numbers an understanding of the impacts of human activities in Antarctic terrestrial environments has become important. The objective of this study was to develop a means for assessing recovery of the ground surface desert pavement following physical disturbance. A set of 11 criteria were identified to assess desert pavement recovery. Assessed criteria were: embeddedness of surface clasts; impressions of removed clasts; degree of clast surface weathering; % overturned clasts; salt on underside of clasts; development of salt coatings; armouring per m(2); colour contrast; evidence of subsidence/melt out; accumulation of salt on cut surfaces; and evidence of patterned ground development. Recovery criteria were assigned a severity/extent rating on a scale from zero to four, zero being highly disturbed, and four being undisturbed. A relative % recovery for each criteria was calculated for each site by comparison with a nearby undisturbed control area, and an overall Mean Recovery Index (MRI) was assigned to each pavement surface. To test the method, 54 sites in the Ross Sea region of Antarctica were investigated including areas disturbed by: bulldozer scraping for road-fill, contouring for infrastructure, geotechnical investigations, and experimental treading trial sites. Disturbances had occurred at timescales ranging from one week to 50 years prior to assessment. The extent of desert pavement recovery at the sites investigated in this study was higher than anticipated. Fifty of the 54 sites investigated were in an intermediate, or higher, stage of desert pavement recovery, 30 sites were in an advanced stage of recovery, and four sites were indistinguishable from adjacent control sites (MRI = 100%). It was found that active surfaces, such as the gravel beach deposits at the Greenpeace World Park Base site at Cape Evans, the aeolian sand deposits at Bull Pass, and the alluvial fan deposits of the Loop Moraine field campsite, recovered relatively

  12. Neogene kinematic history of Nazca-Antarctic-Phoenix slab windows beneath Patagonia and the Antarctic Peninsula

    Science.gov (United States)

    Breitsprecher, Katrin; Thorkelson, Derek J.

    2009-01-01

    The Patagonian slab window is a subsurface tectonic feature resulting from subduction of the Nazca-Antarctic spreading-ridge system (Chile Rise) beneath southern South America. The geometry of the slab window had not been rigorously defined, in part because of the complex nature of the history of ridge subduction in the southeast Pacific region, which includes four interrelated spreading-ridge systems since 20 Ma: first, the Nazca-Phoenix ridge beneath South America, then simultaneous subduction of the Nazca-Antarctic and the northern Phoenix-Antarctic spreading-ridge systems beneath South America, and the southern Phoenix-Antarctic spreading-ridge system beneath Antarctica. Spreading-ridge paleo-geographies and rotation poles for all relevant plate pairs (Nazca, Phoenix, Antarctic, South America) are available from 20 Ma onward, and form the mathematical basis of our kinematic reconstruction of the geometry of the Patagonia and Antarctic slab windows through Neogene time. At approximately 18 Ma, the Nazca-Phoenix-Antarctic oceanic (ridge-ridge-ridge) triple junction enters the South American trench; we recognize this condition as an unstable quadruple junction. Heat flow at this junction and for some distance beneath the forearc would be considerably higher than is generally recognized in cases of ridge subduction. From 16 Ma onward, the geometry of the Patagonia slab window developed from the subduction of the trailing arms of the former oceanic triple junction. The majority of the slab window's areal extent and geometry is controlled by the highly oblique (near-parallel) subduction angle of the Nazca-Antarctic ridge system, and by the high contrast in relative convergence rates between these two plates relative to South America. The very slow convergence rate of the Antarctic slab is manifested by the shallow levels achieved by the slab edge (< 45 km); thus no point on the Antarctic slab is sufficiently deep to generate "normal" mantle-derived arc-type magmas

  13. Sugars in Antarctic aerosol

    Science.gov (United States)

    Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

    2015-10-01

    The processes and transformations occurring in the Antarctic aerosol during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic aerosol collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic aerosol. The total mean concentration of sugars in the aerosol collected at the "Mario Zucchelli" coastal station was 140 pg m-3; as for the aerosol collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the aerosol collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the aerosol collected during the oceanographic cruise.

  14. A Comparative Study of Antarctic Arctic and Himalayan Ice

    Directory of Open Access Journals (Sweden)

    R. C. Pathak

    1989-07-01

    Full Text Available Arctic, Antarctic and inaccessible lofty regions of Himalayas,which are geographically diverse areas and have been a constant source of inspiration, envisages a challenging field of study 'by early adventurers and scientists of the world. Characteristics of ice obtained at Arctic and Antarctic do not possess similar properties. Even thesalient properties of snow and ice of western and central Himalayas vary due to its differing free water content. A study has been carriedout based on recent Antarctic Expedition by Indian scientists and the data gathered along litha-tectonic regions of Himalayas and their characteristics have been compared, wkich brings out stratigraphic and metamorphic characteristics of the ice and snow. In the present paper,an analysis of the ice and snow properties of Arctic, Antarctic and Himalayan regions has been presented.

  15. Testing oils in antarctic soils

    International Nuclear Information System (INIS)

    The resident seals, whales and penguins in Antarctica's Ross Sea region have only environmentally friendly ways of getting around. In contrast, wherever humans go in the Antarctic and whatever they do, be it research, tourism or fishing, they need fuel for their planes, icebreaker ships, land vehicles and generators. Because of this, petroleum hydrocarbons are the most likely source of pollution in the Antarctic. Accidental oil spills often occur near scientific stations, where storage and refuelling of aircraft and vehicles can result in spills. Spills also occur as a consequence of drilling activities. Dr Jackie Aislabie, a microbiologist from the New Zealand government's research company Landcare Research, is leading a program aimed at understanding how oil spills impact on Antarctic soils. The properties of pristine soils were compared with oil-contaminated soil at three locations: Scott Base, Marble Point and in the Wright Valley at Bull Pass. Soils in the Scott Base area are impacted by the establishment and continuous habitation of the base over 40 years, and a hydrocarbon-contaminated site was sampled near a former storage area for drums of mixed oils. Soil sampled from Marble Point was taken from near the old Marble Point camp, which was inhabited from 1957 to about 1963. Oil stains were visible on the soil surface, and are assumed to have been there for more than 30 years. The samples selected for analysis from the Wright Valley came from a spill site near Bull Pass that occurred during seismic bore-hole drilling activities in 1985. The contamination levels ranged from below detection to just over 29,000 μg/g of soil. Descriptions and analyse results are included into a Geographic Information System and associated soils database

  16. Sensitivity of Antarctic fish to ocean warming - an energy budget approach

    OpenAIRE

    Sandersfeld, Tina

    2015-01-01

    Like the Arctic, the Antarctic region hosts some of the hot spots of climatic change. At the western Antarctic Peninsula, alterations of air and water temperature, pH, salinity and sea-ice regime were reported and associated shifts in species abundance and changes in food web structure have already become evident. In contrast, for most high-Antarctic regions, no climate related changes have yet been found. However, future temperature increases are also projected for these areas. Ocean warming...

  17. Antarctic Ozone Hole, 2000

    Science.gov (United States)

    2002-01-01

    Each spring the ozone layer over Antarctica nearly disappears, forming a 'hole' over the entire continent. The hole is created by the interaction of some man-made chemicals-freon, for example-with Antarctica's unique weather patterns and extremely cold temperatures. Ozone in the stratosphere absorbs ultraviolet radiation from the sun, thereby protecting living things. Since the ozone hole was discovered many of the chemicals that destroy ozone have been banned, but they will remain in the atmosphere for decades. In 2000, the ozone hole grew quicker than usual and exceptionally large. By the first week in September the hole was the largest ever-11.4 million square miles. The top image shows the average total column ozone values over Antarctica for September 2000. (Total column ozone is the amount of ozone from the ground to the top of the atmosphere. A relatively typical measurement of 300 Dobson Units is equivalent to a layer of ozone 0.12 inches thick on the Earth's surface. Levels below 220 Dobson Units are considered to be significant ozone depletion.) The record-breaking hole is likely the result of lower than average ozone levels during the Antarctic fall and winter, and exceptionally cold temperatures. In October, however (bottom image), the hole shrank dramatically, much more quickly than usual. By the end of October, the hole was only one-third of it's previous size. In a typical year, the ozone hole does not collapse until the end of November. NASA scientists were surprised by this early shrinking and speculate it is related to the region's weather. Global ozone levels are measured by the Total Ozone Mapping Spectrometer (TOMS). For more information about ozone, read the Earth Observatory's ozone fact sheet, view global ozone data and see these ozone images. Images by Greg Shirah, NASA GSFC Scientific Visualization Studio.

  18. The Pleistocene evolution of the East Antarctic Ice Sheet in the Prydz bay region: Stable isotopic evidence from ODP Site 1167

    Science.gov (United States)

    Theissen, K.M.; Dunbar, R.B.; Cooper, A. K.; Mucciarone, D.A.; Hoffmann, D.

    2003-01-01

    Ocean Drilling Program Leg 188, Prydz Bay, East Antarctica is part of a larger initiative to explore the Cenozoic history of the Antarctic Ice Sheet through direct drilling and sampling of the continental margins. In this paper, we present stable isotopic results from Ocean Drilling Program (ODP) Site 1167 located on the Prydz Channel Trough Mouth Fan (TMF), the first Antarctic TMF to be drilled. The foraminifer-based ??18O record is interpreted along with sedimentary and downhole logging evidence to reconstruct the Quaternary glacial history of Prydz Bay and the adjacent Lambert Glacier Amery Ice Shelf System (LGAISS). We report an electron spin resonance age date of 36. 9 ?? 3.3 ka at 0.45 m below sea floor and correlate suspected glacial-interglacial cycles with the global isotopic stratigraphy to improve the chronology for Site 1167. The ??18O record based on planktonic (Neogloboquadrina pachyderma (s.)) and limited benthic results (Globocassidulina crassa), indicates a trend of ice sheet expansion that was interrupted by a period of reduced ice volume and possibly warmer conditions during the early-mid-Pleistocene (0.9-1.38 Ma). An increase in ?? 18O values after ??? 900 ka appears to coincide with the mid-Pleistocene climate transition and the expansion of the northern hemisphere ice sheet. The ??18O record in the upper 50 m of the stratigraphic section indicates as few as three glacial-interglacial cycles, tentatively assigned as marine isotopic stages (MIS) 16-21, are preserved since the Brunhes/Matuyama paleomagnetic reversal (780 ka). This suggests that there is a large unconformity near the top of the section and/or that there may have been few extreme advances of the ice sheet since the mid-Pleistocene climate transition resulting in lowered sedimentation rates on the Prydz Channel TMF. The stable isotopic record from Site 1167 is one of the few available from the area south of the Antarctic Polar Front that has been linked with the global isotopic

  19. Antarctic ozone depletion

    International Nuclear Information System (INIS)

    Antarctic ozone depletion is most severe during the southern hemisphere spring, when the local reduction in the column amount may be as much as 50 percent. The extent to which this ozone poor air contributes to the observed global ozone loss is a matter of debate, but there is some evidence that fragments of the 'ozone hole' can reach lower latitudes following its breakup in summer. Satellite data show the seasonal evolution of the ozone hole. A new dimension has been added to Antarctic ozone depletion with the advent of large volcanic eruptions such as that from Mount Pinatubo in 1991. (author). 5 refs., 1 fig

  20. Antarctic Porifera database from the Spanish benthic expeditions

    OpenAIRE

    Pilar Rios; Javier Cristobo

    2014-01-01

    The information about the sponges in this dataset is derived from the samples collected during five Spanish Antarctic expeditions: Bentart 94, Bentart 95, Gebrap 96, Ciemar 99/00 and Bentart 2003. Samples were collected in the Antarctic Peninsula and Bellingshausen Sea at depths ranging from 4 to 2044 m using va­rious sampling gears.The Antarctic Porifera database from the Spanish benthic expeditions is unique as it provides in­formation for an under-explored region of the Southern Oc...

  1. Fundamental differences between Arctic and Antarctic ozone depletion

    OpenAIRE

    Solomon, Susan; Haskins, Jessica; Ivy, Diane J.; Min, Flora

    2014-01-01

    Fundamental differences in observed ozone depletion between the Arctic and the Antarctic are shown, clarifying distinctions between both average and extreme ozone decreases in the two hemispheres. Balloon-borne and satellite measurements in the heart of the ozone layer near 18−24 km altitude show that extreme ozone decreases often observed in the Antarctic ozone hole region have not yet been measured in the Arctic in any year, including the unusually cold Arctic spring of 2011. The data provi...

  2. Microbial biomass and basal respiration in Sub-Antarctic and Antarctic soils in the areas of some Russian polar stations

    Directory of Open Access Journals (Sweden)

    E. Abakumov

    2014-03-01

    Full Text Available Antarctica is the unique place for pedological investigations. Soils of Antarctica have been studied intensively during the last century. Antarctic logistic provides the possibility to scientists access the terrestrial landscapes mainly in the places of polar stations. That is why the main and most detailed pedological investigations were conducted in Mc Murdo Valleys, Transantarctic Mountains, South Shetland Islands, Larsemann hills and Schirmacher Oasis. Investigations were conducted during the 53rd and 55th Russian Antarctic expeditions on the base of soil pits and samples collected in Sub-Antarctic and Antarctic regions. Soils of diverse Antarctic landscapes were studied with aim to assess the microbial biomass level, basal respiration rates and metabolic activity of microbial communities. The investigation conducted shows that soils of Antarctic are quite different in profile organization and carbon content. In general, Sub-Antarctic soils are characterized by more developed humus (sod organo-mineral horizons as well as the upper organic layer. The most developed organic layers were revealed in peat soils of King-George Island, where its thickness reach even 80 cm. These soils as well as soils under guano are characterized by the highest amount of total organic carbon (TOC 7.22–33.70%. Coastal and continental soils of Antarctic are presented by less developed Leptosols, Gleysols, Regolith and rare Ornhitosol with TOC levels about 0.37–4.67%. The metabolic ratios and basal respiration were higher in Sub-Antarctic soils than in Antarctic ones which can be interpreted as result of higher amounts of fresh organic remnants in organic and organo-mineral horizons. Also the soils of King-George island have higher portion of microbial biomass (max 1.54 mg g−1 than coastal (max 0.26 mg g−1 and continental (max 0.22 mg g−1 Antarctic soils. Sub-Antarctic soils mainly differ from Antarctic ones in increased organic layers thickness and total

  3. Do Antarctic fish like it hot? What energy allocation can tell us about distribution shifts

    OpenAIRE

    Sandersfeld, Tina; Davison, William; Lamare, Miles D.; Richter, Claudio; Knust, Rainer

    2014-01-01

    Despite evidence for distribution shifts of single species and ecosystem changes as a reaction to global warming, little is known about the underlying processes. As a consequence of warming waters in the Southern Ocean, shifts in species distribution are expected with sub-Antarctic species migrating southward to high-Antarctic waters, while species from temperate regions might intrude sub-Antarctic areas. Species distribution and abundance are driven by reproduction and somatic growth, which ...

  4. [Taxonomical status of the psychrotolerant Antarctic microorganisms].

    Science.gov (United States)

    Romanovskaia, V A; Gladka, G V; Tashireva, A A; Tashirev, A B

    2013-01-01

    The aerobic chemoorganotrophic bacteria, dominating in soils and phytocenosis of the Antarctic Region, on combination of morphological and biochemical properties belong to several taxons of Bacteria domain. Gram-negative strains 3189, 3415 (fam. Halomonadaceae, Halomonas sp.) and 3088, 3468, 3469 (fam. Moraxellaceae, Psychrobacter sp.) belong to phylum Proteobacteria, to class Gammaproteobacteria. Gram-negative strains 3294 3392 (Rhizobiales, fam. Methylobacteriaceae, Methylobacterium sp.) relate to class Alphaproteobacteria of this phylum. Gram-positive strains 3179, 3275, 3470, 3471 (fam. Microbacteriaceae, Cryobacterium sp.), 3054, 3058, 3411 (fam. Corynebacteriaceae, Corynebacterium sp.) and 3194, 3398 (fam. Micrococcaceae, Micrococcus sp.) relate to phylum Actinobacteria, class Actinobacteria. Thus, the psychrophilic and psychrotolerant Antarctic bacteria (aerobic chemoorganotrophic) isolated from phytocenosis and soils of polar region are characterized by wide taxonomic variety. PMID:24450178

  5. Modelling the Antarctic Ice Sheet

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Holm, A.

    2015-01-01

    Science) Antarctic Ice Sheet (DAIS) model (Shaffer 2014) is forced by reconstructed time series of Antarctic temperature, global sea level and ocean subsurface temperature over the last two glacial cycles. In this talk a modelling work of the Antarctic ice sheet over most of the Cenozoic era using the......The Antarctic ice sheet is a major player in the Earth’s climate system and is by far the largest depository of fresh water on the planet. Ice stored in the Antarctic ice sheet (AIS) contains enough water to raise sea level by about 58 m, and ice loss from Antarctica contributed significantly to...... DAIS model will be presented. G. Shaffer (2014) Formulation, calibration and validation of the DAIS model (version 1), a simple Antarctic ice sheet model sensitive to variations of sea level and ocean subsurface temperature, Geosci. Model Dev., 7, 1803‐1818...

  6. Diurnal lower ionosphere electron density variations observed in the South Atlantic Geomagnetic Anomaly and sub-Antarctic region during the occurrence of the major PCA event of 4 August 1972

    Science.gov (United States)

    Costa, A. Mendes da; Piazza, L. Rizzo

    1992-08-01

    VLF phase and amplitude signals simultaneously received in Atibaia and Curitiba, both in Brazil, were analysed during the occurrence of the major proton flare event of 4 August 1972. Phase advances recorded in Stockholm (Sweden) and Inubo (Japan) were also included for comparison purposes. Particular attention was devoted to the NWC (Australia)-Atibaia (Brazil) propagation-path which passes through disturbed regions (geomagnetically), namely the sub-Antarctic region and the South Atlantic Geomagnetic Anomaly (SAGA), and which propagates completely in the southern hemisphere. Following the current mechanisms that allow charged particles to precipitate at low altitudes in the ionosphere ( Dregion), four regions were defined based on the most significant ' L' value involved. By means of successive comparisons with low and mid latitude propagation paths, some parameters typical of the lower ionosphere were deduced for the southern hemisphere in association with PCA events detected in the polar caps. Fitting exponential models to the data analysed, daytime electron density profiles were obtained for different ' L' values throughout the disturbed period.

  7. Underwater Optics in Sub-Antarctic and Antarctic Coastal Ecosystems

    Science.gov (United States)

    Huovinen, Pirjo; Ramírez, Jaime; Gómez, Iván

    2016-01-01

    Understanding underwater optics in natural waters is essential in evaluating aquatic primary production and risk of UV exposure in aquatic habitats. Changing environmental conditions related with global climate change, which imply potential contrasting changes in underwater light climate further emphasize the need to gain insights into patterns related with underwater optics for more accurate future predictions. The present study evaluated penetration of solar radiation in six sub-Antarctic estuaries and fjords in Chilean North Patagonian region (39–44°S) and in an Antarctic bay (62°S). Based on vertical diffuse attenuation coefficients (Kd), derived from measurements with a submersible multichannel radiometer, average summer UV penetration depth (z1%) in these water bodies ranged 2–11 m for UV-B (313 nm), 4–27 m for UV-A (395 nm), and 7–30 m for PAR (euphotic zone). UV attenuation was strongest in the shallow Quempillén estuary, while Fildes Bay (Antarctica) exhibited the highest transparency. Optically non-homogeneous water layers and seasonal variation in transparency (lower in winter) characterized Comau Fjord and Puyuhuapi Channel. In general, multivariate analysis based on Kd values of UV and PAR wavelengths discriminated strongly Quempillén estuary and Puyuhuapi Channel from other study sites. Spatial (horizontal) variation within the estuary of Valdivia river reflected stronger attenuation in zones receiving river impact, while within Fildes Bay a lower spatial variation in water transparency could in general be related to closeness of glaciers, likely due to increased turbidity through ice-driven processes. Higher transparency and deeper UV-B penetration in proportion to UV-A/visible wavelengths observed in Fildes Bay suggests a higher risk for Antarctic ecosystems reflected by e.g. altered UV-B damage vs. photorepair under UV-A/PAR. Considering that damage repair processes often slow down under cool temperatures, adverse UV impact could be

  8. Antarctic science preserve polluted

    Science.gov (United States)

    Simarski, Lynn Teo

    Geophysicists are alarmed at the electromagnetic pollution of a research site in the Antarctic specifically set aside to study the ionosphere and magnetosphere. A private New Zealand communications company called Telecom recently constructed a satellite ground station within the boundaries of this Site of Special Scientific Interest (SSSI), protected since the mid-1970s. The placement of a commercial facility within this site sets an ominous precedent not only for the sanctity of other SSSIs, but also for Specially Protected Areas—preserves not even open to scientific research, such as certain penguin rookeries.The roughly rectangular, one-by-one-half mile site, located at Arrival Heights not far from McMurdo Station, is one of a number of areas protected under the Antarctic treaty for designated scientific activities. Many sites are set aside for geological or biological research, but this is the only one specifically for physical science.

  9. In search of human-associated bacterial pathogens in Antarctic wildlife: report from six penguin colonies regularly visited by tourists.

    Science.gov (United States)

    Bonnedahl, Jonas; Broman, Tina; Waldenström, Jonas; Palmgren, Helena; Niskanen, Taina; Olsen, Björn

    2005-08-01

    We investigated the potential role of Antarctic tourism in the introduction of human-associated pathogens into Antarctic wildlife. We collected and analyzed 233 fecal samples from eight bird species. The samples were collected at six localities on the Antarctic Peninsula, which often is visited by tourists. Every sample was investigated for pathogens of potential human origin: Campylobacter jejuni, Salmonella spp., and Yersina spp. None of these bacteria was found. Our data suggest that the tourism industry so far has achieved its goal of not introducing pathogens into the Antarctic region. There is, however, an urgent need to further investigate the situation in areas closer to permanent Antarctic settlements. PMID:16201212

  10. Carbonate Deposition on Antarctic Shelves

    Science.gov (United States)

    Frank, T. D.; James, N. P.; Malcolm, I.

    2011-12-01

    Limestones associated with glaciomarine deposits occur throughout the geologic record but remain poorly understood. The best-described examples formed during major ice ages of the Neoproterozoic and Late Paleozoic. Quaternary analogs on Antarctic shelves have received comparatively little study. Here, we report on the composition, spatial distribution, and stratigraphic context of carbonate sediments contained in piston cores from the Ross Sea. The goals of this work are to (1) document the nature and distribution of carbonate sediments on the Ross Sea continental shelf and (2) examine temporal relationships to Quaternary glaciation. Results will be used to develop criteria that will improve understanding of analogous deposits in the ancient record. All carbonate-rich intervals in piston cores from the Ross Rea, now housed at the Antarctic Marine Geology Research Facility at Florida State University, were examined and described in detail. Sediment samples were disaggregated and sieved into size fractions before description with paleontological analysis carried out on the coarsest size fraction (>250 microns). Carbonate-rich sediments are concentrated in the northwestern Ross Sea, along the distal margins of Mawson and Pennell Banks. Calcareous facies include a spectrum of lithologies that range from fossiliferous mud, sand, and gravel to skeletal floatstone-rudstone and bafflestone. Floatstone-rudstone and bafflestone is most abundant along western-facing slopes in areas protected from the Antarctic Coastal Current. Sand-prone facies dominate the tops of banks and mud-prone, often spicultic, facies occur in deeper areas. The carbonate factory is characterized by a low-diversity, heterozoan assemblage that is dominated by stylasterine hydrocorals, barnacles, and bryozoans. Molluscs and echinoids are present but not abundant. Planktic and benthic foraminifera are ubiquitous components of the sediment matrix, which is locally very rich in sponge spicules. Biota rarely

  11. A Bivalve Proxy for Neogene Antarctic Shelf Marine Environments

    Science.gov (United States)

    Clark, N. A.; Williams, M.; Quilty, P. G.; Leng, M. J.; Zalasiewicz, J. A.; Smellie, J.; Dowsett, H. J.

    2012-12-01

    The Neogene shallow-marine successions of the Antarctic Peninsula and of the East Antarctic region preserve rich assemblages of bivalve molluscs. These bivalve molluscs provide a detailed record of palaeoseasonality in the chemical signature and morphology of their shells that can be used to assess sea temperatures and sea ice extent for the Antarctic shelf during the Pliocene. Analyses identify the following. 1) Neogene bivalves from James Ross Island, Antarctic Peninsula, comprise material of late Miocene through to late Pliocene age. Results identify warm (ca. 3-10 °C) early Pliocene sea temperatures, and cooler late Pliocene sea temperatures (ca. 0-4 °C), and flag a cooling trend which is consistent with the evolution of polar climate through this interval. 2) Neogene bivalves from the Larsemann Hills, East Antarctic, identify generally warmer than present sea temperatures (ca. 0-11 °C) in the early Pliocene consistent with data from other fossil groups of this age, including dolphins and silicoflagellates. The new data may provide significant ground truth for climate models assessing the Southern Ocean and Antarctic shelf climate.

  12. Satellite magnetic anomalies of the Antarctic crust

    Directory of Open Access Journals (Sweden)

    D. E. Alsdorf

    2000-06-01

    Full Text Available Spatially and temporally static crustal magnetic anomalies are contaminated by static core field effects above spherical harmonic degree 12 and dynamic, large-amplitude external fields. To extract crustal magnetic anomalies from the measurements of NASA's Magsat mission, we separate crustal signals from both core and external field effects. In particular, we define Magsat anomalies relative to the degree 11 field and use spectral correlation theory to reduce them for external field effects. We obtain a model of Antarctic crustal thickness by comparing the region's terrain gravity effects to free-air gravity anomalies derived from the Earth Gravity Model 1996 (EGM96. To separate core and crustal magnetic effects, we obtain the pseudo-magnetic effect of the crustal thickness variations from their gravity effect via Poisson's theorem for correlative potentials. We compare the pseudo-magnetic effect of the crustal thickness variations to field differences between degrees 11 and 13 by spectral correlation analysis. We thus identify and remove possible residual core field effects in the Magsat anomalies relative to the degree 11 core field. The resultant anomalies reflect possible Antarctic contrasts due both to crustal thickness and intracrustal variations of magnetization. In addition, they provide important constraints on the geologic interpretation of aeromagnetic survey data, such as are available for the Weddell Province. These crustal anomalies also may be used to correct for long wavelength errors in regional compilations of near-surface magnetic survey data. However, the validity of these applications is limited by the poor quality of the Antarctic Magsat data that were obtained during austral Summer and Fall when south polar external field activity was maximum. Hence an important test and supplement for the Antarctic crustal Magsat anomaly map will be provided by the data from the recently launched Ørsted mission, which will yield coverage

  13. Ecuadorian antarctic act

    International Nuclear Information System (INIS)

    To develop research in this continent involves to take communion with earth where the cold pole of the planet is located, the stormiest sea of the world surround it and where the capricious continental and geographical distribution permits the pass of meteorological violent and continuous systems. The Ecuador, in execution of the acquired commitments like Full Member of the System of the Antarctic Treaty, carried out the VII Expedition to the White Continent with an extensive program of scientific investigation in the field of: Sciences of Life, Sciences of the Earth and Atmospheric Sciences, so much in the environment of the Pacific Southeast, the Drake Pass, Bransfield Strait and the nearby ecosystems antarctic to Point Fort William in the Greenwich Island, site where the Ecuadorian station Pedro Vicente Maldonado is located. The scientific articles, result of the fruitful work of national investigator is consigned in this fourth edition. This publication constitutes our contribution to the world in the knowledge, understanding and handling of the marvelous White Continent from the middle of our planet, Ecuador

  14. Balance of the West Antarctic Ice Sheet

    Science.gov (United States)

    2002-01-01

    For several decades, measurements of the West Antarctic Ice Sheet showed it to be retreating rapidly. But new data derived from satellite-borne radar sensors show the ice sheet to be growing. Changing Antarctic ice sheets remains an area of high scientific interest, particularly in light of recent global warming concerns. These new findings are significant because scientists estimate that sea level would rise 5-6 meters (16-20 feet) if the ice sheet collapsed into the sea. Do these new measurements signal the end of the ice sheet's 10,000-year retreat? Or, are these new satellite data simply much more accurate than the sparse ice core and surface measurements that produced the previous estimates? Another possibility is that the ice accumulation may simply indicate that the ice sheet naturally expands and retreats in regular cycles. Cryologists will grapple with these questions, and many others, as they examine the new data. The image above depicts the region of West Antarctica where scientists measured ice speed. The fast-moving central ice streams are shown in red. Slower tributaries feeding the ice streams are shown in blue. Green areas depict slow-moving, stable areas. Thick black lines depict the areas that collect snowfall to feed their respective ice streams. Reference: Ian Joughin and Slawek Tulaczyk Science Jan 18 2002: 476-480. Image courtesy RADARSAT Antarctic Mapping Project

  15. Emerging spatial patterns in Antarctic prokaryotes

    Directory of Open Access Journals (Sweden)

    Chun Wie eChong

    2015-09-01

    Full Text Available Recent advances in knowledge of patterns of biogeography in terrestrial eukaryotic organisms have led to a fundamental paradigm shift in understanding of the controls and history of life on land in Antarctica, and its interactions over the long term with the glaciological and geological processes that have shaped the continent. However, while it has long been recognized that the terrestrial ecosystems of Antarctica are dominated by microbes and their processes, knowledge of microbial diversity and distributions has lagged far behind that of the macroscopic eukaryote organisms. Increasing human contact with and activity in the continent is leading to risks of biological contamination and change in a region whose isolation has protected it for millions of years at least; these risks may be particularly acute for microbial communities which have, as yet, received scant recognition and attention. Even a matter apparently as straightforward as Protected Area designation in Antarctica requires robust biodiversity data which, in most parts of the continent, remain almost completely unavailable. A range of important contributing factors mean that it is now timely to reconsider the state of knowledge of Antarctic terrestrial prokaryotes. Rapid advances in molecular biological approaches are increasingly demonstrating that bacterial diversity in Antarctica may be far greater than previously thought, and that there is overlap in the environmental controls affecting both Antarctic prokaryotic and eukaryotic communities. Bacterial dispersal mechanisms and colonization patterns remain largely unaddressed, although evidence for regional evolutionary differentiation is rapidly accruing and, with this, there is increasing appreciation of patterns in regional bacterial biogeography in this large part of the globe. In this review, we set out to describe the state of knowledge of Antarctic prokaryote diversity patterns, drawing analogy with those of eukaryote

  16. The ARM West Antarctic Radiation Experiment (AWARE)

    Science.gov (United States)

    Lubin, Dan; Bromwich, David; Vogelmann, Andrew; Verlinde, Johannes; Russell, Lynn

    2016-04-01

    West Antarctica is one of the most rapidly warming regions on Earth, and its changing climate in both atmosphere and ocean is linked to loss of Antarctic ice mass and global sea level rise. The specific mechanisms for West Antarctic Ice Sheet (WAIS) warming are not fully understood, but are hypothesized to involve linkage between moisture from Southern Ocean storm tracks and the surface energy balance over the WAIS, and related teleconnections with subtropical and tropical meteorology. This present lack of understanding has motivated a climate science and cloud physics campaign jointly supported by the US National Science Foundation (NSF) and Department of Energy (DOE), called the Atmospheric Radiation Measurement Program (ARM) West Antarctic Radiation Experiment (AWARE). The DOE's second ARM Mobile Facility (AMF2) was deployed to McMurdo Station on Ross Island in November 2015 and will operate through December 2016. The AMF2 includes (1) cloud research radars, both scanning and zenith, operating in the Ka- and X-bands, (2) high spectral resolution and polarized micropulse lidars, and (3) a suite of shortwave and longwave broadband and spectral radiometers. A second suite of instruments is deployed at the WAIS Divide Ice Camp on the West Antarctic plateau during December 2015 and January 2016. The WAIS instrument suite provides (1) measurement of all surface energy balance components, (2) a polarized micropulse lidar and shortwave spectroradiometer, (3) microwave total water column measurement, and (4) four times daily rawinsonde launches which are the first from West Antarctica since 1967. There is a direct linkage between the WAIS instrument suite and the AMF2 at McMurdo, in that air masses originating in Southern Ocean storm tracks that are driven up over the WAIS often subsequently descend over the Ross Ice Shelf and arrive at Ross Island. Preliminary data are already illustrating the prevalence of mixed-phase clouds and their role in the surface energy balance

  17. The spatial extent and dynamics of the Antarctic Cold Reversal

    Science.gov (United States)

    Pedro, Joel B.; Bostock, Helen C.; Bitz, Cecilia M.; He, Feng; Vandergoes, Marcus J.; Steig, Eric J.; Chase, Brian M.; Krause, Claire E.; Rasmussen, Sune O.; Markle, Bradley R.; Cortese, Giuseppe

    2016-01-01

    Antarctic ice cores show that a millennial-scale cooling event, the Antarctic Cold Reversal (14,700 to 13,000 years ago), interrupted the last deglaciation. The Antarctic Cold Reversal coincides with the Bølling-Allerød warm stage in the North Atlantic, providing an example of the inter-hemispheric coupling of abrupt climate change generally referred to as the bipolar seesaw. However, the ocean-atmosphere dynamics governing this coupling are debated. Here we examine the extent and expression of the Antarctic Cold Reversal in the Southern Hemisphere using a synthesis of 84 palaeoclimate records. We find that the cooling is strongest in the South Atlantic and all regions south of 40° S. At the same time, the terrestrial tropics and subtropics show abrupt hydrologic variations that are significantly correlated with North Atlantic climate changes. Our transient global climate model simulations indicate that the observed extent of Antarctic Cold Reversal cooling can be explained by enhanced northward ocean heat transport from the South to North Atlantic, amplified by the expansion and thickening of sea ice in the Southern Ocean. The hydrologic variations at lower latitudes result from an opposing enhancement of southward heat transport in the atmosphere mediated by the Hadley circulation. Our findings reconcile previous arguments about the relative dominance of ocean and atmospheric heat transports in inter-hemispheric coupling, demonstrating that the spatial pattern of past millennial-scale climate change reflects the superposition of both.

  18. Regional climate signal vs. local noise: a two-dimensional view of water isotopes in Antarctic firn at Kohnen Station, Dronning Maud Land

    Science.gov (United States)

    Münch, Thomas; Kipfstuhl, Sepp; Freitag, Johannes; Meyer, Hanno; Laepple, Thomas

    2016-07-01

    In low-accumulation regions, the reliability of δ18O-derived temperature signals from ice cores within the Holocene is unclear, primarily due to the small climate changes relative to the intrinsic noise of the isotopic signal. In order to learn about the representativity of single ice cores and to optimise future ice-core-based climate reconstructions, we studied the stable-water isotope composition of firn at Kohnen Station, Dronning Maud Land, Antarctica. Analysing δ18O in two 50 m long snow trenches allowed us to create an unprecedented, two-dimensional image characterising the isotopic variations from the centimetre to the 100-metre scale. Our results show seasonal layering of the isotopic composition but also high horizontal isotopic variability caused by local stratigraphic noise. Based on the horizontal and vertical structure of the isotopic variations, we derive a statistical noise model which successfully explains the trench data. The model further allows one to determine an upper bound for the reliability of climate reconstructions conducted in our study region at seasonal to annual resolution, depending on the number and the spacing of the cores taken.

  19. Climate Change Impacts in the sub-Antarctic Islands Technical Report N.2 of ONERC

    International Nuclear Information System (INIS)

    Difficult to apprehend as a whole, the polar regions constitute the Arctic to the North, an ocean surrounded by emerged lands, and the Antarctic to the South, a continent bordered by the Austral Ocean where a belt of sub Antarctic islands lies. Climate change impacts on sub Antarctic islands are varied, direct and indirect: glacier retreat, more favourable conditions for introduced species, marine biodiversity modification, etc. This report discusses the French, British, Australian, South African and New Zealand sub Antarctic islands, the climatic evolutions and the resulting impacts, focused especially on biodiversity. The Observatoire National sur les Effets du Rechauffement Climatique and the International Polar Foundation have been joined in this endeavour by the French polar institute Paul-Emile Victor, the administration of the French Southern and Antarctic Lands (TAAF in French) and the International Union for the Conservation of Nature. (authors)

  20. Local scaling characteristics of Antarctic surface layer turbulence

    Directory of Open Access Journals (Sweden)

    S. Basu

    2010-03-01

    Full Text Available Over the past years, several studies have validated Nieuwstadt's local scaling hypothesis by utilizing turbulence observations from the mid-latitude, nocturnal stable boundary layers. In this work, we probe into the local scaling characteristics of polar, long-lived stable boundary layers by analyzing turbulence data from the South Pole region of the Antarctic Plateau.

  1. Extremophiles in an Antarctic Marine Ecosystem

    Directory of Open Access Journals (Sweden)

    Iain Dickinson

    2016-01-01

    Full Text Available Recent attempts to explore marine microbial diversity and the global marine microbiome have indicated a large proportion of previously unknown diversity. However, sequencing alone does not tell the whole story, as it relies heavily upon information that is already contained within sequence databases. In addition, microorganisms have been shown to present small-to-large scale biogeographical patterns worldwide, potentially making regional combinations of selection pressures unique. Here, we focus on the extremophile community in the boundary region located between the Polar Front and the Southern Antarctic Circumpolar Current in the Southern Ocean, to explore the potential of metagenomic approaches as a tool for bioprospecting in the search for novel functional activity based on targeted sampling efforts. We assessed the microbial composition and diversity from a region north of the current limit for winter sea ice, north of the Southern Antarctic Circumpolar Front (SACCF but south of the Polar Front. Although, most of the more frequently encountered sequences  were derived from common marine microorganisms, within these dominant groups, we found a proportion of genes related to secondary metabolism of potential interest in bioprospecting. Extremophiles were rare by comparison but belonged to a range of genera. Hence, they represented interesting targets from which to identify rare or novel functions. Ultimately, future shifts in environmental conditions favoring more cosmopolitan groups could have an unpredictable effect on microbial diversity and function in the Southern Ocean, perhaps excluding the rarer extremophiles.

  2. CHAMP Magnetic Anomalies of the Antarctic Crust

    Science.gov (United States)

    Kim, Hyung Rae; Gaya-Pique, Luis R.; vonFrese, Ralph R. B.; Taylor, Patrick T.; Kim, Jeong Woo

    2003-01-01

    Regional magnetic signals of the crust are strongly masked by the core field and its secular variations components and hence difficult to isolate in the satellite measurements. In particular, the un-modeled effects of the strong auroral external fields and the complicated- behavior of the core field near the geomagnetic poles conspire to greatly reduce the crustal magnetic signal-to-noise ratio in the polar regions relative to the rest of the Earth. We can, however, use spectral correlation theory to filter the static lithospheric and core field components from the dynamic external field effects. To help isolate regional lithospheric from core field components, the correlations between CHAMP magnetic anomalies and the pseudo magnetic effects inferred from gravity-derived crustal thickness variations can also be exploited.. Employing these procedures, we processed the CHAMP magnetic observations for an improved magnetic anomaly map of the Antarctic crust. Relative to the much higher altitude Orsted and noisier Magsat observations, the CHAMP magnetic anomalies at 400 km altitude reveal new details on the effects of intracrustal magnetic features and crustal thickness variations of the Antarctic.

  3. Towers for Antarctic Telescopes

    Science.gov (United States)

    Hammerschlag, R. H.; Bettonvil, F. C. M.; Jägers, A. P. L.; Nielsen, G.

    To take advantage of the exceptional seeing above the boundary layer on Antarctic sites, a high-resolution telescope must be mounted on a support tower. An open transparent tower of framework minimizes the upward temperature-disturbed airflow. A typical minimum height is 30m. The tower platform has to be extremely stable against wind-induced rotational motions, which have to be less than fractions of an arc second, unusually small from a mechanical engineering viewpoint. In a traditional structure, structural deflections result in angular deflections of the telescope platform, which introduce tip and tilt motions in the telescope. However, a structure that is designed to deflect with parallel motion relative to the horizontal plane will undergo solely translation deflections in the telescope platform and thus will not degrade the image. The use of a parallel motion structure has been effectively demonstrated in the design of the 15-m tower for the Dutch Open Telescope (DOT) on La Palma. Special framework geometries are developed, which make it possible to construct high towers in stories having platforms with extreme stability against wind-induced tilt. These geometric solutions lead to constructions, being no more massive than a normal steel framework carrying the same load. Consequently, these lightweight towers are well suited to difficult sites as on Antarctica. A geometry with 4 stories has been worked out.

  4. Evolution and ecology of antarctic sponges

    OpenAIRE

    Vargas Ramirez, Sergio

    2012-01-01

    Sponges are abundant and species-rich in Antarctic waters, and play important roles in the benthic ecosystems of the continent. The taxonomy of Antarctic sponges is, to some extent, well established, yet the phylogenetic relationships of this fauna remain unknown. Here, the first contributions to the knowledge of the evolution of Antarctic sponges are presented. A molecular phylogeny for the common Antarctic shelf glass sponge genus Rossella is provided. Based on nuclear and mitochondrial mar...

  5. Evidence for widespread endemism among Antarctic micro-organisms

    Science.gov (United States)

    Vyverman, Wim; Verleyen, Elie; Wilmotte, Annick; Hodgson, Dominic A.; Willems, Anne; Peeters, Karolien; Van de Vijver, Bart; De Wever, Aaike; Leliaert, Frederik; Sabbe, Koen

    2010-08-01

    Understanding the enormous diversity of microbes, their multiple roles in the functioning of ecosystems, and their response to large-scale environmental and climatic changes, are at the forefront of the international research agenda. In Antarctica, where terrestrial and lacustrine environments are predominantly microbial realms, an active and growing community of microbial ecologists is probing this diversity and its role in ecosystem processes. In a broader context, this work has the potential to make a significant contribution to the long-standing debate as to whether microbes are fundamentally different from macroorganisms in their biogeography. According to the ubiquity hypothesis, microbial community composition is not constrained by dispersal limitation and is solely the result of species sorting along environmental gradients. However, recent work on several groups of microalgae is challenging this view. Global analyses using morphology-based diatom inventories have demonstrated that, in addition to environmental harshness, geographical isolation underlies the strong latitudinal gradients in local and regional diversity in the Southern hemisphere. Increasing evidence points to a strong regionalization of diatom floras in the Antarctic and sub-Antarctic regions, mirroring the biogeographical regions that have been recognized for macroorganisms. Likewise, the application of molecular-phylogenetic techniques to cultured and uncultured diversity revealed a high number of Antarctic endemics among cyanobacteria and green algae. Calibration of these phylogenies suggests that several clades have an ancient evolutionary history within the Antarctic continent, possibly dating back to 330 Ma. These findings are in line with the current view on the origin of Antarctic terrestrial metazoa, including springtails, chironomids and mites, with most evidence suggesting a long history of geographic isolation on a multi-million year, even pre-Gondwana break-up timescale.

  6. Depletion in Antarctic ozone and associated climatic change

    International Nuclear Information System (INIS)

    Perhaps the most significant discovery in the atmospheric sciences in the last decade has been the observation of large decreases in ozone. These losses in ozone occur during austral spring, and from 1979 the severity of the depletion increased non-monotonically until September of 1987 when the lowest column ozone amounts ever recorded were observed in Antarctica. While the surprising ozone hole in the remote icy continent of Antarctica emphasizes the potential importance and complexity of processes in the high latitude stratosphere, it also motivated this study on the nature of greenhouse effect on polar climate due to perturbations in column ozone amount in association with observed increases in other trace gases in the Antarctic atmosphere. The authors have examined the potential climatic effects of changes in the concentration of greenhouse gases on thermal structure of the Antarctic atmosphere using both steady-state and time-dependent climate models. When the authors incorporate the greenhouse effect of increases in methane, nitrous oxide, carbon dioxide and chlorofluorocarbons in association with decrease in ozone at the levels of maximum concentration in their radiative flux computations for the Antarctic region, the net result is a surface warming which is in fair agreement with that inferred from mean Antarctic temperature series. Further, the stratospheric cooling due to the ozone hole phenomenon is not only restricted to low and middle stratosphere but also extends deep into the upper Antarctic stratosphere, particularly in the beginning of November. In view of this, it is possible that the polar stratospheric warming phenomenon associated with planetary wave events could be significantly disturbed by ozone depletion in the Antarctic atmosphere, leading to appreciable perturbations in the general circulation

  7. Antarctic Porifera database from the Spanish benthic expeditions

    Directory of Open Access Journals (Sweden)

    Pilar Rios

    2014-04-01

    Full Text Available The information about the sponges in this dataset is derived from the samples collected during five Spanish Antarctic expeditions: Bentart 94, Bentart 95, Gebrap 96, Ciemar 99/00 and Bentart 2003. Samples were collected in the Antarctic Peninsula and Bellingshausen Sea at depths ranging from 4 to 2044 m using va­rious sampling gears.The Antarctic Porifera database from the Spanish benthic expeditions is unique as it provides in­formation for an under-explored region of the Southern Ocean (Bellingshausen Sea. It fills an information gap on Antarctic deep-sea sponges, for which there were previously very few data.This phylum is an important part of the Antarctic biota and plays a key role in the structure of the Antarctic marine benthic community due to its considerable diversity and predominance in different areas. It is often a dominant component of Southern Ocean benthic communities.The quality of the data was controlled very thoroughly with GPS systems onboard the R/V Hesperides and by checking the data against the World Porifera Database (which is part of the World Register of Marine Species, WoRMS. The data are therefore fit for completing checklists, inclusion in biodivers­ity pattern analysis and niche modelling. The authors can be contacted if any additional information is needed before carrying out detailed biodiversity or biogeographic studies.The dataset currently contains 767 occurrence data items that have been checked for systematic reliability. This database is not yet complete and the collection is growing. Specimens are stored in the author’s collection at the Spanish Institute of Oceanography (IEO in the city of Gijón (Spain. The data are available in GBIF.

  8. Antarctic Porifera database from the Spanish benthic expeditions.

    Science.gov (United States)

    Rios, Pilar; Cristobo, Javier

    2014-01-01

    THE INFORMATION ABOUT THE SPONGES IN THIS DATASET IS DERIVED FROM THE SAMPLES COLLECTED DURING FIVE SPANISH ANTARCTIC EXPEDITIONS: Bentart 94, Bentart 95, Gebrap 96, Ciemar 99/00 and Bentart 2003. Samples were collected in the Antarctic Peninsula and Bellingshausen Sea at depths ranging from 4 to 2044 m using various sampling gears. The Antarctic Porifera database from the Spanish benthic expeditions is unique as it provides information for an under-explored region of the Southern Ocean (Bellingshausen Sea). It fills an information gap on Antarctic deep-sea sponges, for which there were previously very few data. This phylum is an important part of the Antarctic biota and plays a key role in the structure of the Antarctic marine benthic community due to its considerable diversity and predominance in different areas. It is often a dominant component of Southern Ocean benthic communities. The quality of the data was controlled very thoroughly with GPS systems onboard the R/V Hesperides and by checking the data against the World Porifera Database (which is part of the World Register of Marine Species, WoRMS). The data are therefore fit for completing checklists, inclusion in biodiversity pattern analysis and niche modelling. The authors can be contacted if any additional information is needed before carrying out detailed biodiversity or biogeographic studies. The dataset currently contains 767 occurrence data items that have been checked for systematic reliability. This database is not yet complete and the collection is growing. Specimens are stored in the author's collection at the Spanish Institute of Oceanography (IEO) in the city of Gijón (Spain). The data are available in GBIF. PMID:24843257

  9. Water masses, ocean fronts, and the structure of Antarctic seabird communities: Putting the eastern Bellingshausen Sea in perspective

    Science.gov (United States)

    Ribic, Christine A.; Ainley, David G.; Glenn Ford, R.; Fraser, William R.; Tynan, Cynthia T.; Woehler, Eric J.

    2011-07-01

    Waters off the western Antarctic Peninsula (i.e., the eastern Bellingshausen Sea) are unusually complex owing to the convergence of several major fronts. Determining the relative influence of fronts on occurrence patterns of top-trophic species in that area, therefore, has been challenging. In one of the few ocean-wide seabird data syntheses, in this case for the Southern Ocean, we analyzed ample, previously collected cruise data, Antarctic-wide, to determine seabird species assemblages and quantitative relationships to fronts as a way to provide context to the long-term Palmer LTER and the winter Southern Ocean GLOBEC studies in the eastern Bellingshausen Sea. Fronts investigated during both winter (April-September) and summer (October-March) were the southern boundary of the Antarctic Circumpolar Current (ACC), which separates the High Antarctic from the Low Antarctic water mass, and within which are embedded the marginal ice zone and Antarctic Shelf Break Front; and the Antarctic Polar Front, which separates the Low Antarctic and the Subantarctic water masses. We used clustering to determine species' groupings with water masses, and generalized additive models to relate species' densities, biomass and diversity to distance to respective fronts. Antarctic-wide, in both periods, highest seabird densities and lowest species diversity were found in the High Antarctic water mass. In the eastern Bellingshausen, seabird density in the High Antarctic water mass was lower (as low as half that of winter) than found in other Antarctic regions. During winter, Antarctic-wide, two significant species groups were evident: one dominated by Adélie penguins ( Pygoscelis adeliae) (High Antarctic water mass) and the other by petrels and prions (no differentiation among water masses); in eastern Bellingshausen waters during winter, the one significant species group was composed of species from both Antarctic-wide groups. In summer, Antarctic-wide, a High Antarctic group dominated

  10. Ophiuroidea das regiões antártica e subantártica: 1. sobre três espécies de Gorgonocephalidae e Ophiacanthidae Ophiuroidea from antarctic and subantarctic regions: 1. on three species of Gorgonocephalidae and Ophiacanthidae

    Directory of Open Access Journals (Sweden)

    Ana Maria Gouveia Monteiro

    1983-01-01

    Full Text Available É estudada a distribuição geográfica e a variação de caracteres morfológicos de três espécies de ofiuroides (OpiLacantha antartica, Astrotoma agassizzi e Gorgonecephalus chilensis das regiões Antártica e Subantãrtica. São também apresentadas observações sobre biologia reprodutiva.The geographical distribution and the variation of morphological characters of three (Gorgonecephalus chilensis, Astroma agassizii, Ophiacantha antartica from the Antarctic and Subantarctic regions are studied. Observations on reproductive biology are presented.

  11. The Antarctic - the wild card in the global climate

    International Nuclear Information System (INIS)

    The overview gives an account of studies of snowfall, ice melting and formation and water flow patterns in the Antarctic during the present global warming period. It also gives a survey of the ice area in the region. The sea water warming is dramatic and a large floating glacier seems to be decomposing which is disrupting the oceanographic and ecological relations in the region and globally and is significantly influencing the global climate

  12. Feeding repellence in Antarctic bryozoans

    Science.gov (United States)

    Figuerola, Blanca; Núñez-Pons, Laura; Moles, Juan; Avila, Conxita

    2013-11-01

    The Antarctic sea star Odontaster validus and the amphipod Cheirimedon femoratus are important predators in benthic communities. Some bryozoans are part of the diet of the asteroid and represent both potential host biosubstrata and prey for this omnivorous lysianassid amphipod. In response to such ecological pressure, bryozoans are expected to develop strategies to deter potential predators, ranging from physical to chemical mechanisms. However, the chemical ecology of Antarctic bryozoans has been scarcely studied. In this study we evaluated the presence of defenses against predation in selected species of Antarctic bryozoans. The sympatric omnivorous consumers O. validus and C. femoratus were selected to perform feeding assays with 16 ether extracts (EE) and 16 butanol extracts (BE) obtained from 16 samples that belonged to 13 different bryozoan species. Most species (9) were active (12 EE and 1 BE) in sea star bioassays. Only 1 BE displayed repellence, indicating that repellents against the sea star are mainly lipophilic. Repellence toward C. femoratus was found in all species in different extracts (10 EE and 12 BE), suggesting that defenses against the amphipod might be both lipophilic and hydrophilic. Interspecific and intraspecific variability of bioactivity was occasionally detected, suggesting possible environmental inductive responses, symbiotic associations, and/or genetic variability. Multivariate analysis revealed similarities among species in relation to bioactivities of EE and/or BE. These findings support the hypothesis that, while in some cases alternative chemical or physical mechanisms may also provide protection, repellent compounds play an important role in Antarctic bryozoans as defenses against predators.

  13. Antarctic Thresholds - Ecosystem Resilience and Adaptation a new SCAR-Biology Programme

    OpenAIRE

    Gutt, Julian; Adams, Byron; Bracegirdle, Thomas; Cowan, Don; Cummings, Vonda; di Prisco, Guido; Gradinger, Rolf; Isla, Enrique; McIntyre, Trevor; Murphy, Eugene; Peck, Lloyd; Schloss, Irene; Smith, Craig; Suckling, Coleen; Takahashi, Akinori

    2013-01-01

    Stresses on Antarctic ecosystems result from environmental change, including extreme events, and from (other) human impacts. Consequently, Antarctic habitats are changing, some at a rapid pace while others are relatively stable. A cascade of responses from molecular through organismic to the community level are expected. The differences in biological complexity and evolutionary histories between both polar regions and the rest of the planet suggest that stresses on polar ...

  14. Isolation and cellular fatty acid composition of psychrotrophic Halomonas strains from Antarctic sea water

    OpenAIRE

    Vipra Vijay Jadhav; Amit Yadav; Shouche, Yogesh S.; Rama Kaustubh Bhadekar

    2013-01-01

    Microorganisms from extreme environments such as Arctic, Antarctic and Polar regions modulate their membrane fatty acids to survive in such habitats. Characterization of such microorganisms helps in understanding their physiological behavior. In view of this, the present article describes isolation, characterization and cellular fatty acid composition of three bacterial isolates from Antarctic sea water samples. All the three isolates (BRI 6, 29 and 31) were psychrotrophic Gram negative rods....

  15. Investigation of carbon dioxide phase shift possibility under extreme Antarctic winter conditions

    CERN Document Server

    Vashchenko, V M

    2014-01-01

    The Antarctic winter atmosphere minimal temperature and pressure series reveal that $CO_2$ phase shift (deposition) is possible in some extreme cases, even leading to possible $CO_2$ snow phenomenon at Vostok Antarctic station and in other near South Pole regions. A hypothesis has been formulated that stable $CO_2$ snow cover might have formed in Earth past which may influence interpretation of glacial chronology records. This effect may also manifest in other minor gases. Its global climate role is discussed.

  16. A multivariate analysis of Antarctic sea ice since 1979

    Energy Technology Data Exchange (ETDEWEB)

    Magalhaes Neto, Newton de; Evangelista, Heitor [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Tanizaki-Fonseca, Kenny [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Universidade Federal Fluminense (UFF), Dept. Analise Geoambiental, Inst. de Geociencias, Niteroi, RJ (Brazil); Penello Meirelles, Margareth Simoes [Universidade do Estado do Rio de Janeiro (UERJ)/Geomatica, Maracana, Rio de Janeiro, RJ (Brazil); Garcia, Carlos Eiras [Universidade Federal do Rio Grande (FURG), Laboratorio de Oceanografia Fisica, Rio Grande, RS (Brazil)

    2012-03-15

    Recent satellite observations have shown an increase in the total extent of Antarctic sea ice, during periods when the atmosphere and oceans tend to be warmer surrounding a significant part of the continent. Despite an increase in total sea ice, regional analyses depict negative trends in the Bellingshausen-Amundsen Sea and positive trends in the Ross Sea. Although several climate parameters are believed to drive the formation of Antarctic sea ice and the local atmosphere, a descriptive mechanism that could trigger such differences in trends are still unknown. In this study we employed a multivariate analysis in order to identify the response of the Antarctic sea ice with respect to commonly utilized climate forcings/parameters, as follows: (1) The global air surface temperature, (2) The global sea surface temperature, (3) The atmospheric CO{sub 2} concentration, (4) The South Annular Mode, (5) The Nino 3, (6) The Nino (3 + 4, 7) The Nino 4, (8) The Southern Oscillation Index, (9) The Multivariate ENSO Index, (10) the Total Solar Irradiance, (11) The maximum O{sub 3} depletion area, and (12) The minimum O{sub 3} concentration over Antarctica. Our results indicate that western Antarctic sea ice is simultaneously impacted by several parameters; and that the minimum, mean, and maximum sea ice extent may respond to a separate set of climatic/geochemical parameters. (orig.)

  17. Low genetic diversity in Antarctic populations of the lichen-forming ascomycete Cetraria aculeata and its photobiont

    Directory of Open Access Journals (Sweden)

    Stephanie Domaschke

    2012-03-01

    Full Text Available Lichens, symbiotic associations of fungi (mycobionts and green algae or cyanobacteria (photobionts, are poikilohydric organisms that are particularly well adapted to withstand adverse environmental conditions. Terrestrial ecosystems of the Antarctic are therefore largely dominated by lichens. The effects of global climate change are especially pronounced in the maritime Antarctic and it may be assumed that the lichen vegetation will profoundly change in the future. The genetic diversity of populations is closely correlated to their ability to adapt to changing environmental conditions and to their future evolutionary potential. In this study, we present evidence for low genetic diversity in Antarctic mycobiont and photobiont populations of the widespread lichen Cetraria aculeata. We compared between 110 and 219 DNA sequences from each of three gene loci for each symbiont. A total of 222 individuals from three Antarctic and nine antiboreal, temperate and Arctic populations were investigated. The mycobiont diversity is highest in Arctic populations, while the photobionts are most diverse in temperate regions. Photobiont diversity decreases significantly towards the Antarctic but less markedly towards the Arctic, indicating that ecological factors play a minor role in determining the diversity of Antarctic photobiont populations. Richness estimators calculated for the four geographical regions suggest that the low genetic diversity of Antarctic populations is not a sampling artefact. Cetraria aculeata appears to have diversified in the Arctic and subsequently expanded its range into the Southern Hemisphere. The reduced genetic diversity in the Antarctic is most likely due to founder effects during long-distance colonization.

  18. The South Atlantic in the Fine-Resolution Antarctic Model

    Directory of Open Access Journals (Sweden)

    D. P. Stevens

    Full Text Available The geographical area covered by the Fine-Resolution Antarctic Model (FRAM includes that part of the South Atlantic south of 24°S. A description of the dynamics and thermodynamics of this region of the model is presented. Both the mean and eddy fields in the model are in good agreement with reality, although the magnitude of the transients is somewhat reduced. The heat flux is northward and in broad agreement with many other estimates. Agulhas eddies are formed by the model and propagate westward into the Atlantic providing a mechanism for fluxing heat from the Indian Ocean. The confluence of the Brazil and Falkland currents produces a strong front and a large amount of mesoscale activity. In the less stratified regions to the south, topographic steering of the Antarctic circumpolar current is important.

  19. Penguin eggshell membranes reflect homogeneity of mercury in the marine food web surrounding the Antarctic Peninsula

    Energy Technology Data Exchange (ETDEWEB)

    Brasso, Rebecka L., E-mail: rlb1196@uncw.edu [University of North Carolina Wilmington, Department of Biology and Marine Biology, 601 South College Road, Wilmington, NC 28403 (United States); Polito, Michael J. [University of North Carolina Wilmington, Department of Biology and Marine Biology, 601 South College Road, Wilmington, NC 28403 (United States); Lynch, Heather J. [Ecology and Evolution Department, 640 Life Sciences Bldg., Stony Brook University, Stony Brook, NY 11794 (United States); Naveen, R. [Oceanites Inc., PO Box 15259, Chevy Chase, MD 20825 (United States); Emslie, Steven D. [University of North Carolina Wilmington, Department of Biology and Marine Biology, 601 South College Road, Wilmington, NC 28403 (United States)

    2012-11-15

    Remote regions such as the Antarctic have become increasingly important for investigations into far-reaching anthropogenic impacts on the environment, most recently in regard to the global mercury cycle. Spatial patterns of mercury availability in four regions of the Antarctic Peninsula were investigated using three species of sympatrically breeding Pygoscelis penguins as biomonitors. Eggshells with intact membranes from Adelie, Gentoo, and Chinstrap penguins were collected at 24 breeding colonies in the South Orkney Islands, South Shetland Islands, eastern Antarctic Peninsula, and western Antarctic Peninsula during the 2006/2007 austral summer. In addition, we compared eggshell membrane mercury concentrations with eggshell stable isotope values ({delta}{sup 15}N and {delta}{sup 13}C) to determine if species-specific trophic or foraging habitat preferences influenced female mercury exposure prior to breeding. With few exceptions, mercury concentrations were found to be fairly homogeneous throughout the Antarctic Peninsula suggesting little spatial variation in the risk of exposure to dietary mercury in this food web. Mercury concentrations in Gentoo and Adelie penguins were similar while Chinstrap penguins tended to have higher eggshell membrane mercury concentrations than their congeners. However, inter and intra-specific differences in eggshell membrane mercury concentration were not related to eggshell {delta}{sup 15}N or {delta}{sup 13}C values, a likely result of all three species foraging at similar trophic positions. The lack of regional-scale differences in mercury availability in this marine ecosystem may be a reflection of generally uniform atmospheric deposition and upwelling of regionally homogeneous deep water rather than from geographically distinct point sources. -- Highlights: Black-Right-Pointing-Pointer We examined regional patterns of mercury availability in the Antarctic Peninsula. Black-Right-Pointing-Pointer Three species of Pygoscelis

  20. Penguin eggshell membranes reflect homogeneity of mercury in the marine food web surrounding the Antarctic Peninsula

    International Nuclear Information System (INIS)

    Remote regions such as the Antarctic have become increasingly important for investigations into far-reaching anthropogenic impacts on the environment, most recently in regard to the global mercury cycle. Spatial patterns of mercury availability in four regions of the Antarctic Peninsula were investigated using three species of sympatrically breeding Pygoscelis penguins as biomonitors. Eggshells with intact membranes from Adélie, Gentoo, and Chinstrap penguins were collected at 24 breeding colonies in the South Orkney Islands, South Shetland Islands, eastern Antarctic Peninsula, and western Antarctic Peninsula during the 2006/2007 austral summer. In addition, we compared eggshell membrane mercury concentrations with eggshell stable isotope values (δ15N and δ13C) to determine if species-specific trophic or foraging habitat preferences influenced female mercury exposure prior to breeding. With few exceptions, mercury concentrations were found to be fairly homogeneous throughout the Antarctic Peninsula suggesting little spatial variation in the risk of exposure to dietary mercury in this food web. Mercury concentrations in Gentoo and Adélie penguins were similar while Chinstrap penguins tended to have higher eggshell membrane mercury concentrations than their congeners. However, inter and intra-specific differences in eggshell membrane mercury concentration were not related to eggshell δ15N or δ13C values, a likely result of all three species foraging at similar trophic positions. The lack of regional-scale differences in mercury availability in this marine ecosystem may be a reflection of generally uniform atmospheric deposition and upwelling of regionally homogeneous deep water rather than from geographically distinct point sources. -- Highlights: ► We examined regional patterns of mercury availability in the Antarctic Peninsula. ► Three species of Pygoscelis penguins were used as biomonitors. ► Chinstrap penguins tended to have higher mercury than Ad

  1. Determination of the Antarctic region active margin basement by using integration of the information coming from the multichannel seismic analysis and the magnetometry; Determinacao do embasamento da margen ativa da regiao Antartica pela integracao de informacoes provenientes da sismica multicanal e da magnetometria

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Luiz Carlos [Diretoria de Hidrografia e Navegacao, XX (Brazil); Gomes, Benedito Souza [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Gamboa, Luiz Antonio P. [Universidade Federal Fluminense, Niteroi, RJ (Brazil)

    1999-07-01

    Geophysical measurements were carried out in the Western Margin of the Antarctic Peninsula and Bransfield Strait by the Brazilian Antarctic Program during the summers of 1987 and 1988. The present work, using a continued seismic multi channel and magnetometry data profile crossing the area, intends to present a two-dimensional model of the interface sediment/basement and contribute to the understanding of the complex geology verified in the studying area. By this model, the main provinces of the are (Deep Ocean, South Shetland Trench, Accretionary Prism, Volcanic Arc South Shetland Islands and Bransfield Basin) could be determined. The seismic and magnetic measurements information when superposed can attribute more consistencies to the interpreted basement; although each method has its particular resolution. This way, when the seismic interpretation was not possible due to complex structures disposition, magnetic measurements could offer good estimation about basement depth. The fit between both methods (seismic and magnetic measurements) was reasonable both on the oceanic basin and in the region of Bransfield Strait. The magnetometry, as as well seismic, was sensible to the dip of Drake Plate at South Shetland Trench and the Intrusive occurrence at Bransfield Basin axis. (author)

  2. Antarctic skuas recognize individual humans.

    Science.gov (United States)

    Lee, Won Young; Han, Yeong-Deok; Lee, Sang-Im; Jablonski, Piotr G; Jung, Jin-Woo; Kim, Jeong-Hoon

    2016-07-01

    Recent findings report that wild animals can recognize individual humans. To explain how the animals distinguish humans, two hypotheses are proposed. The high cognitive abilities hypothesis implies that pre-existing high intelligence enabled animals to acquire such abilities. The pre-exposure to stimuli hypothesis suggests that frequent encounters with humans promote the acquisition of discriminatory abilities in these species. Here, we examine individual human recognition abilities in a wild Antarctic species, the brown skua (Stercorarius antarcticus), which lives away from typical human settlements and was only recently exposed to humans due to activities at Antarctic stations. We found that, as nest visits were repeated, the skua parents responded at further distances and were more likely to attack the nest intruder. Also, we demonstrated that seven out of seven breeding pairs of skuas selectively responded to a human nest intruder with aggression and ignored a neutral human who had not previously approached the nest. The results indicate that Antarctic skuas, a species that typically inhabited in human-free areas, are able to recognize individual humans who disturbed their nests. Our findings generally support the high cognitive abilities hypothesis, but this ability can be acquired during a relatively short period in the life of an individual as a result of interactions between individual birds and humans. PMID:26939544

  3. Primary productivity, phytoplankton standing crop and physico-chemical characteristics of the Antarctic and adjacent central Indian Ocean waters

    Digital Repository Service at National Institute of Oceanography (India)

    JiyalalRam, M.

    Primary productivity, phytoplankton pigments and physico-chemical properties were studied in Antarctic waters and adjoining Indian Ocean between 11 degrees and 67 degrees E longitudes from polynya region (60 degrees S) to equator during the austral...

  4. The effect of environmental change on vascular plant and cryptogam communities from the Falkland Islands and the Maritime Antarctic

    OpenAIRE

    Convey Peter; Huiskes Ad; Bokhorst Stef; Aerts Rien

    2007-01-01

    Abstract Background Antarctic terrestrial vegetation is subject to one of the most extreme climates on Earth. Currently, parts of Antarctica are one of the fastest warming regions on the planet. During 3 growing seasons, we investigated the effect of experimental warming on the diversity and abundance of coastal plant communities in the Maritime Antarctic region (cryptogams only) and the Falkland Islands (vascular plants only). We compared communities from the Falkland Islands (51°S, mean ann...

  5. Extreme phenotypic plasticity in metabolic physiology of Antarctic Demosponges

    Directory of Open Access Journals (Sweden)

    Simon Anthony Morley

    2016-01-01

    Full Text Available Seasonal measurements of the metabolic physiology of four Antarctic demosponges and their associated assemblages, maintained in a flow through aquarium facility, demonstrated one of the largest differences in seasonal strategies between species and their associated sponge communities. The sponge oxygen consumption measured here exhibited both the lowest and highest seasonal changes for any Antarctic species; metabolic rates varied from a 25% decrease to a 5.8 fold increase from winter to summer, a range which was greater than all 17 Antarctic marine species (encompassing 8 phyla previously investigated and amongst the highest recorded for any marine environment. The differences in nitrogen excretion, metabolic substrate utilisation and tissue composition between species were, overall, greater than seasonal changes. The largest seasonal difference in tissue composition was an increase in CHN (Carbon, Hydrogen and Nitrogen content in Homaxinella balfourensis, a pioneer species in ice-scour regions, which changed growth form to a twig-like morph in winter. The considerable flexibility in seasonal and metabolic physiology across the Demospongiae likely enables these species to respond to rapid environmental change such as ice-scour, reductions in sea ice cover and ice-shelf collapse in the Polar Regions, shifting the paradigm that polar sponges always live life in the slow lane. Great phenotypic plasticity in physiology has been linked to differences in symbiotic community composition, and this is likely to be a key factor in the global success of sponges in all marine environments and their dominant role in many climax communities.

  6. Results and perspectives of tectonomagnetic investigations in the Western Antarctic

    Directory of Open Access Journals (Sweden)

    Ihor O. Chobotok

    2009-06-01

    Full Text Available The results of long-term (1998-2005 yrs. tectonomagnetic investigations in the Western Antarctic near the location
    of Ukrainian Antarctic Station «Academic Vernadsky» are reviewed. The peculiarities of the Earth’s
    anomalous magnetic field and its dynamic temporal variations (tectonomagnetic anomalies were studied using
    the newly founded tectonomagnetic polygon. Near the Argentine Archipelago intensive tectonomagnetic effects
    up to -2.8 nT/year were determined. Their spatial-temporal structure agrees with tectonic structure elements. We
    suggest that the nature of such effects is caused by a piezomagnetic effect under the influence of stretching tectonic
    forces (few bars per year in sub-latitudinal direction. Perspectives of tectonomagnetic investigations in the
    region are discussed.

  7. Treatment and prevention of infection following bites of the Antarctic fur seal (Arctocephalus gazella

    Directory of Open Access Journals (Sweden)

    Kouliev T

    2015-04-01

    Full Text Available Timur Kouliev,1 Victoria Cui2 1Beijing United Family Hospital, Beijing, People's Republic of China; 2Department of Biological Sciences, Columbia University, New York, NY, USA Abstract: In recent decades, an increasing number of people have traveled to sub-Antarctic and Antarctic regions each year for research, tourism, and resource exploitation. Hunting of Antarctic fur seals (Arctocephalus gazella almost pushed the species to extinction in the early 1900s, but populations have since shown rapid and substantial recovery. The species' range has re-expanded to include several islands south of the Antarctic Convergence, most notably South Georgia, and now overlaps with many popular Antarctic travel destinations. Both male and female fur seals can become extremely aggressive when provoked, and their bites, if not properly treated, pose a significant risk of infection by microorganisms not usually encountered in cases of animal bites. In this report, we present the case of a patient treated for a fur seal bite during an Antarctic expedition cruise, review the literature concerning seal bites, and suggest the use of antibiotic prophylaxis to prevent complications. Keywords: zoonotic, polar tourism, prophylaxis, seal finger, expedition medicine

  8. Annual cycle of Antarctic baseline aerosol: controlled by photooxidation-limited aerosol formation

    Directory of Open Access Journals (Sweden)

    M. Fiebig

    2013-09-01

    Full Text Available This article investigates the annual cycle observed in the Antarctic baseline aerosol scattering coefficient, total particle number concentration, and particle number size distribution (PNSD as measured at Troll Atmospheric Observatory. Mie-theory shows that the annual cycles in microphysical and optical aerosol properties have a common cause. By comparison with observations at other Antarctic stations, it is shown that the annual cycle is not a local phenomenon, but common to Central Antarctic baseline air masses. Observations of ground-level ozone at Troll as well as backward plume calculations for the air masses arriving at Troll demonstrate that the baseline air masses originate from the free troposphere and lower stratosphere region, and descend over the Central Antarctic continent. The Antarctic summer PNSD is dominated by particles with diameters 3/(MJ m. Further research is proposed to investigate the applicability of this number to other atmospheric reservoirs, and to use the observed annual cycle in Antarctic baseline aerosol properties as a benchmark for the representation of natural atmospheric aerosol processes in climate models.

  9. Shifts in soil microorganisms in response to warming are consistent across a range of Antarctic environments.

    Science.gov (United States)

    Yergeau, Etienne; Bokhorst, Stef; Kang, Sanghoon; Zhou, Jizhong; Greer, Charles W; Aerts, Rien; Kowalchuk, George A

    2012-03-01

    Because of severe abiotic limitations, Antarctic soils represent simplified systems, where microorganisms are the principal drivers of nutrient cycling. This relative simplicity makes these ecosystems particularly vulnerable to perturbations, like global warming, and the Antarctic Peninsula is among the most rapidly warming regions on the planet. However, the consequences of the ongoing warming of Antarctica on microorganisms and the processes they mediate are unknown. Here, using 16S rRNA gene pyrosequencing and qPCR, we report highly consistent responses in microbial communities across disparate sub-Antarctic and Antarctic environments in response to 3 years of experimental field warming (+0.5 to 2 °C). Specifically, we found significant increases in the abundance of fungi and bacteria and in the Alphaproteobacteria-to-Acidobacteria ratio, which could result in an increase in soil respiration. Furthermore, shifts toward generalist bacterial communities following warming weakened the linkage between the bacterial taxonomic and functional richness. GeoChip microarray analyses also revealed significant warming effects on functional communities, specifically in the N-cycling microorganisms. Our results demonstrate that soil microorganisms across a range of sub-Antarctic and Antarctic environments can respond consistently and rapidly to increasing temperatures. PMID:21938020

  10. Divergent trajectories of Antarctic surface melt under two twenty-first-century climate scenarios

    Science.gov (United States)

    Trusel, Luke D.; Frey, Karen E.; Das, Sarah B.; Karnauskas, Kristopher B.; Kuipers Munneke, Peter; van Meijgaard, Erik; van den Broeke, Michiel R.

    2015-12-01

    Ice shelves modulate Antarctic contributions to sea-level rise and thereby represent a critical, climate-sensitive interface between the Antarctic ice sheet and the global ocean. Following rapid atmospheric warming over the past decades, Antarctic Peninsula ice shelves have progressively retreated, at times catastrophically. This decay supports hypotheses of thermal limits of viability for ice shelves via surface melt forcing. Here we use a polar-adapted regional climate model and satellite observations to quantify the nonlinear relationship between surface melting and summer air temperature. Combining observations and multimodel simulations, we examine melt evolution and intensification before observed ice shelf collapse on the Antarctic Peninsula. We then assess the twenty-first-century evolution of surface melt across Antarctica under intermediate and high emissions climate scenarios. Our projections reveal a scenario-independent doubling of Antarctic-wide melt by 2050. Between 2050 and 2100, however, significant divergence in melt occurs between the two climate scenarios. Under the high emissions pathway by 2100, melt on several ice shelves approaches or surpasses intensities that have historically been associated with ice shelf collapse, at least on the northeast Antarctic Peninsula.

  11. The impact of global warming on the Antarctic mass balance and global sea level

    International Nuclear Information System (INIS)

    The onset of global warming from increasing greenhouse gases in the atmosphere can have a number of important different impacts on the Antarctic ice sheet. These include increasing basal melt of ice shelves, faster flow of the grounded ice, increased surface ablation in coastal regions, and increased precipitation over the interior. An analysis of these separate terms by ice sheet modeling indicates that the impact of increasing ice sheet flow rates on sea level does not become a dominant factor until 100-200 years after the realization of the warming. For the time period of the next 100 years the most important impact on sea level from the Antarctic mass balance can be expected to result from increasing precipitation minus evaporation balance over the grounded ice. The present Antarctic net accumulation and coastal ice flux each amount to about 2,000 km3 yr-1, both of which on their own would equate to approximately 6 mm yr-1 of sea level change. The present rate of sea level rise of about 1.2 mm yr-1 is therefore equivalent to about 20% imbalance in the Antarctic mass fluxes. The magnitude of the changes to the Antarctic precipitation and evaporation have been studied by a series of General Circulation Model experiments, using a model which gives a reasonable simulation of the present Antarctic climate, including precipitation and evaporation. The experiments examine the changes in the Antarctic precipitation (P) and evaporation (E) resulting separately from decreasing incrementally the Antarctic sea ice concentration and from global warming accompanied by decreased sea ice cover. For total sea ice removal the changes obtained were P:+23%; E:-8%; (P-E):+48%. For global warming with sea ice reduction by about two thirds the changes were P:+47%; E:+22%; (P-E):+68%

  12. Genetic population structure in the Antarctic benthos: insights from the widespread amphipod, Orchomenella franklini.

    Directory of Open Access Journals (Sweden)

    Helena Phoenix Baird

    Full Text Available Currently there is very limited understanding of genetic population structure in the Antarctic benthos. We conducted one of the first studies of microsatellite variation in an Antarctic benthic invertebrate, using the ubiquitous amphipod Orchomenella franklini (Walker, 1903. Seven microsatellite loci were used to assess genetic structure on three spatial scales: sites (100 s of metres, locations (1-10 kilometres and regions (1000 s of kilometres sampled in East Antarctica at Casey and Davis stations. Considerable genetic diversity was revealed, which varied between the two regions and also between polluted and unpolluted sites. Genetic differentiation among all populations was highly significant (F(ST = 0.086, R(ST = 0.139, p<0.001 consistent with the brooding mode of development in O. franklini. Hierarchical AMOVA revealed that the majority of the genetic subdivision occurred across the largest geographical scale, with N(em≈1 suggesting insufficient gene flow to prevent independent evolution of the two regions, i.e., Casey and Davis are effectively isolated. Isolation by distance was detected at smaller scales and indicates that gene flow in O. franklini occurs primarily through stepping-stone dispersal. Three of the microsatellite loci showed signs of selection, providing evidence that localised adaptation may occur within the Antarctic benthos. These results provide insights into processes of speciation in Antarctic brooders, and will help inform the design of spatial management initiatives recently endorsed for the Antarctic benthos.

  13. Assessment of trace metals in droppings of Adélie penguins (Pygoscelis adeliae) from different locations of the Antarctic Peninsula area

    Institute of Scientific and Technical Information of China (English)

    Jos E Celis; Winfred Espejo; Ricardo Barra; Daniel Gonzalez-Acua; Francisca Gonzalez; Solange Jara

    2015-01-01

    In recent decades, polar regions of the planet have witnessed an increase in human presence. Antarctica is considered one of the most pristine regions of the world, but it could be affected by pollution owing to anthropogenic activities, particularly in the Antarctic Peninsula. Human presence can increase the levels of some trace metals in Antarctic environments, an issue that needs to be evaluated. To acquire data of trace metal contamination in the Antarctic Peninsula region, concentrations (dry weight) of Cd, Pb, As, Cu, Hg and Zn in fresh excrement of Adélie penguins were determined by atomic absorption spectrophotometry. During the 2012/2013 austral summer, samples were collected from four important nesting sites on the Antarctic Peninsula:Arctowski Base, Kopaitic Island (both sites in the northern Antarctic Peninsula), Yalour Island and Avian Island (both sites in the southern Antarctic Peninsula). Data showed that Adélie penguin excreta had significantly higher levels (mg·kg-1) of As, Cd, Hg, Pb and Cu at Arctowski Base and Kopaitic Island, both sites that have major anthropogenic activities that probably contributed to increased metal levels. The levels of trace metals in Adélie penguins were similar to those reported in excreta of Antarctic species in previous studies, and lower than those in excreta of other Antarctic animals. Data suggest that metals ingested by these penguin species that feed in the sea, end up in terrestrial ecosystems.

  14. On the Atmospheric Correction of Antarctic Airborne Hyperspectral Data

    Directory of Open Access Journals (Sweden)

    Martin Black

    2014-05-01

    Full Text Available The first airborne hyperspectral campaign in the Antarctic Peninsula region was carried out by the British Antarctic Survey and partners in February 2011. This paper presents an insight into the applicability of currently available radiative transfer modelling and atmospheric correction techniques for processing airborne hyperspectral data in this unique coastal Antarctic environment. Results from the Atmospheric and Topographic Correction version 4 (ATCOR-4 package reveal absolute reflectance values somewhat in line with laboratory measured spectra, with Root Mean Square Error (RMSE values of 5% in the visible near infrared (0.4–1 µm and 8% in the shortwave infrared (1–2.5 µm. Residual noise remains present due to the absorption by atmospheric gases and aerosols, but certain parts of the spectrum match laboratory measured features very well. This study demonstrates that commercially available packages for carrying out atmospheric correction are capable of correcting airborne hyperspectral data in the challenging environment present in Antarctica. However, it is anticipated that future results from atmospheric correction could be improved by measuring in situ atmospheric data to generate atmospheric profiles and aerosol models, or with the use of multiple ground targets for calibration and validation.

  15. Miocene Antarctic Terrestrial Realm

    Science.gov (United States)

    Ashworth, A. C.; Lewis, A.; Marchant, D. R.

    2009-12-01

    The discovery of several locations in the Transantarctic Mountains that contain macrofossils and pollen is transforming our understanding of late Cenozoic Antarctica. The most southerly location is on the Beardmore Glacier (85.1°S) about 500 km from the South Pole. The environment was an active glacial margin in which plants, insects and freshwater mollusks inhabited the sand and gravel bars and small lakes on an outwash plain. In addition to leaves and wood of dwarf Nothofagus (Southern Beech) shrubs, achenes of Ranunculus (Buttercup), in situ cushion growth forms of mosses and a vascular plant, the assemblages contains various exoskeletal parts of carabid and curculionid beetles and a cyclorrhaphan fly, the shells of freshwater bivalve and gastropod species and a fish tooth. Initially the deposits were assigned a Pliocene age (3.5 Ma) but a mid- to early Miocene age is more probable (c. 14 - 25 Ma) based on correlation of fossil pollen from the deposits with 39Ar/40Ar dated pollen assemblages from the McMurdo Dry Valleys locations. The oldest location within the Dry Valleys also involved an active ice margin but was part of a valley system that was completely deglaciated for intervals long enough for thick paleosols to develop. The Friis Hills fossil deposits of the Taylor Valley region (77.8°S) are at least 19.76 Ma based on the 39Ar/40Ar age of a volcanic ash bed. The valley floor during the non-glacial phases had poorly-drained soils and the extensive development of mossy mires. Wood and leaves of Nothofagus are abundant in lacustrine deposits. The silts of shallow fluvial channels contain abundant megaspores and spiky leaves of the aquatic lycopod Isoetes (Quillwort). Fossils of beetles are also present in these deposits. During the glacial phases, proglacial lakes were surrounded by dwarfed, deciduous Nothofagus shrubs. The youngest fossils recovered from the Dry Valleys are from the Olympus Range (77.5°S) with an age of 14.07 Ma. The environment was an

  16. Natural thermoluminescence of Antarctic meteorites and related studies

    Science.gov (United States)

    Benoit, Paul H.; Sears, Derek W. G.

    1998-01-01

    The natural thermoluminescence (TL) laboratory's primary purpose is to provide data on newly recovered Antarctic meteorites that can be included in discovery announcements and to investigate the scientific implications of the data. Natural TL levels of meteorites are indicators of recent thermal history and terrestrial history, and the data can be used to study the orbital/radiation history of groups of meteorites (e.g., H chondrites) or to study the processes leading to the concentration of meteorites at certain sites in Antarctica. An important application of these data is the identification of fragments, or "pairs" of meteorites produced during atmospheric passage or during terrestrial weathering. Thermoluminescence data are particularly useful for pairing within the most common meteorite classes, which typically exhibit very limited petrographic and chemical diversity. Although not originally part of the laboratory's objectives, TL data are also useful in the identification and classification of petrographically or mineralogically unusual meteorites, including unequilibrated ordinary chondrites and some basaltic achondrites. In support of its primary mission, the laboratory also engages in TL studies of modern falls, finds from hot deserts, and terrestrial analogs and conducts detailed studies of the TL properties of certain classes of meteorites. These studies include the measurement of TL profiles in meteorites, the determination of TL levels of finds from the Sahara and the Nullarbor region of Australia, and comparison of TL data to other indicators of irradiation or terrestrial history, such as cosmogenic noble gas and radionuclide abundances. Our current work can be divided into five subcategories, (a) TL survey of Antarctic meteorites, (b) pairing and field relations of Antarctic meteorites, (c) characterization of TL systematics of meteorites, (d) comparison of natural TL and other terrestrial age indicators for Antarctic meteorites, and for meteorites

  17. Antarctic-type blue whale calls recorded at low latitudes in the Indian and eastern Pacific Oceans

    Science.gov (United States)

    Stafford, Kathleen M.; Bohnenstiehl, DelWayne R.; Tolstoy, Maya; Chapp, Emily; Mellinger, David K.; Moore, Sue E.

    2004-10-01

    Blue whales, Balaenoptera musculus, were once abundant around the Antarctic during the austral summer, but intensive whaling during the first half of the 20th century reduced their numbers by over 99%. Although interannual variability of blue whale occurrence on the Antarctic feeding grounds was documented by whalers, little was known about where the whales spent the winter months. Antarctic blue whales produce calls that are distinct from those produced by blue whales elsewhere in the world. To investigate potential winter migratory destinations of Antarctic blue whales, we examined acoustic data for these signals from two low-latitude locales: the eastern tropical Pacific Ocean and the Indian Ocean. Antarctic-type blue whale calls were detected on hydrophones in both regions during the austral autumn and winter (May-September), with peak detections in July. Calls occurred over relatively brief periods in both oceans, suggesting that there may be only a few animals migrating so far north and/or producing calls. Antarctic blue whales appear to use both the Indian and eastern Pacific Oceans concurrently, indicating that there is not a single migratory destination. Acoustic data from the South Atlantic and from mid-latitudes in the Indian or Pacific Oceans are needed for a more global understanding of migratory patterns and destinations of Antarctic blue whales.

  18. Advances through collaboration: sharing seismic reflection data via the Antarctic Seismic Data Library System for Cooperative Research (SDLS)

    Science.gov (United States)

    Wardell, N.; Childs, J. R.; Cooper, A. K.

    2007-01-01

    The Antarctic Seismic Data Library System for Cooperative Research (SDLS) has served for the past 16 years under the auspices of the Antarctic Treaty (ATCM Recommendation XVI-12) as a role model for collaboration and equitable sharing of Antarctic multichannel seismic reflection (MCS) data for geoscience studies. During this period, collaboration in MCS studies has advanced deciphering the seismic stratigraphy and structure of Antarctica’s continental margin more rapidly than previously. MCS data compilations provided the geologic framework for scientific drilling at several Antarctic locations and for high-resolution seismic and sampling studies to decipher Cenozoic depositional paleoenvironments. The SDLS successes come from cooperation of National Antarctic Programs and individual investigators in “on-time” submissions of their MCS data. Most do, but some do not. The SDLS community has an International Polar Year (IPY) goal of all overdue MCS data being sent to the SDLS by end of IPY. The community science objective is to compile all Antarctic MCS data to derive a unified seismic stratigraphy for the continental margin – a stratigraphy to be used with drilling data to derive Cenozoic circum-Antarctic paleobathymetry maps and local-to-regional scale paleoenvironmental histories.

  19. Circumpolar Diversity and Geographic Differentiation of mtDNA in the Critically Endangered Antarctic Blue Whale (Balaenoptera musculus intermedia)

    OpenAIRE

    Angela L Sremba; Brittany Hancock-Hanser; Branch, Trevor A.; Rick L LeDuc; C Scott Baker

    2012-01-01

    The Antarctic blue whale (Balaenoptera musculus intermedia) was hunted to near extinction between 1904 and 1972, declining from an estimated initial abundance of more than 250,000 to fewer than 400. Here, we describe mtDNA control region diversity and geographic differentiation in the surviving population of the Antarctic blue whale, using 218 biopsy samples collected under the auspices of the International Whaling Commission (IWC) during research cruises from 1990-2009. Microsatellite genoty...

  20. Mapping lichen distribution on the Antarctic Peninsula using remote sensing, lichen spectra and photographic documentation by citizen scientists

    OpenAIRE

    Casanovas, Paula; Black, Martin; Fretwell, Peter; Convey, Peter

    2015-01-01

    On the Antarctic Peninsula, lichens are the most diverse botanical component of the terrestrial ecosystem. However, detailed information on the distribution of lichens on the Antarctic Peninsula region is scarce, and the data available exhibit significant heterogeneity in sampling frequency and effort. Satellite remote sensing, in particular the use of the Normalized Difference Vegetation Index (NDVI), has facilitated determination of vegetation richness and cover distribution in some remote ...

  1. Concentration of trace elements in feathers of three Antarctic penguins: Geographical and interspecific differences

    Energy Technology Data Exchange (ETDEWEB)

    Jerez, Silvia [Area de Toxicologia, Facultad de Veterinaria, Universidad de Murcia, Campus de Espinardo, 30100 Murcia (Spain); Motas, Miguel, E-mail: motas@um.es [Area de Toxicologia, Facultad de Veterinaria, Universidad de Murcia, Campus de Espinardo, 30100 Murcia (Spain); Palacios, Maria Jose; Valera, Francisco [Departamento de Ecologia Funcional y Evolutiva, Estacion Experimental de Zonas Aridas, CSIC, Carretera de Sacramento s/n, 04120 La Canada de San Urbano, Almeria (Spain); Cuervo, Jose Javier; Barbosa, Andres [Departamento de Ecologia Funcional y Evolutiva, Estacion Experimental de Zonas Aridas, CSIC, Carretera de Sacramento s/n, 04120 La Canada de San Urbano, Almeria (Spain); Departamento de Ecologia Evolutiva, Museo Nacional de Ciencias Naturales, CSIC, C/Jose Gutierrez Abascal 2, 28006 Madrid (Spain)

    2011-10-15

    Antarctica is often considered as one of the last pristine regions, but it could be affected by pollution at global and local scale. Concentrations of Al, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Cd and Pb were determinated by ICP-MS in feathers (n = 207 individuals) of gentoo, chinstrap and Adelie penguin collected in 8 locations throughout the Antarctic Peninsula (2006-2007). The highest levels of several elements were found in samples from King George Island (8.08, 20.29 and 1.76 {mu}g g{sup -1} dw for Cr, Cu and Pb, respectively) and Deception Island (203.13, 3.26 and 164.26 {mu}g g{sup -1} dw for Al, Mn and Fe, respectively), where probably human activities and large-scale transport of pollutants contribute to increase metal levels. Concentrations of Cr, Mn, Cu, Se or Pb, which are similar to others found in different regions of the world, show that some areas in Antarctica are not utterly pristine. - Highlights: > We study levels of trace elements in feathers of Antarctic penguins. > Eight different rookeries throughout the Antarctic Peninsula were sampled. > Interspecific (gentoo, chinstrap, Adelie) and geographical differences were tested. > Relatively high metal levels were found in areas with major human presence. > Penguin feather can be useful for metals monitoring in the Antarctic environment. - Trace element levels in feathers of three penguin species from the Antarctic Peninsula indicate the presence of pollution in certain locations.

  2. Concentration of trace elements in feathers of three Antarctic penguins: Geographical and interspecific differences

    International Nuclear Information System (INIS)

    Antarctica is often considered as one of the last pristine regions, but it could be affected by pollution at global and local scale. Concentrations of Al, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Cd and Pb were determinated by ICP-MS in feathers (n = 207 individuals) of gentoo, chinstrap and Adelie penguin collected in 8 locations throughout the Antarctic Peninsula (2006-2007). The highest levels of several elements were found in samples from King George Island (8.08, 20.29 and 1.76 μg g-1 dw for Cr, Cu and Pb, respectively) and Deception Island (203.13, 3.26 and 164.26 μg g-1 dw for Al, Mn and Fe, respectively), where probably human activities and large-scale transport of pollutants contribute to increase metal levels. Concentrations of Cr, Mn, Cu, Se or Pb, which are similar to others found in different regions of the world, show that some areas in Antarctica are not utterly pristine. - Highlights: → We study levels of trace elements in feathers of Antarctic penguins. → Eight different rookeries throughout the Antarctic Peninsula were sampled. → Interspecific (gentoo, chinstrap, Adelie) and geographical differences were tested. → Relatively high metal levels were found in areas with major human presence. → Penguin feather can be useful for metals monitoring in the Antarctic environment. - Trace element levels in feathers of three penguin species from the Antarctic Peninsula indicate the presence of pollution in certain locations.

  3. The Scientific Committee on Antarctic Research (SCAR) in the IPY 2007-2009

    Science.gov (United States)

    Kennicutt, M. C.; Wilson, T. J.; Summerhayes, C.

    2005-05-01

    The Scientific Committee on Antarctic Research (SCAR) initiates, develops, and coordinates international scientific research in the Antarctic region. SCAR is assuming a leadership position in the IPY primarily through its five major Scientific Research Programs; ACE, SALE, EBA, AGCS, and ICESTAR; which will be briefly described.Antarctic Climate Evolution (ACE) promotes the exchange of data and ideas between research groups focusing on the evolution of Antarctica's climate system and ice sheet. The program will: (1) quantitatively assess the climate and glacial history of Antarctica; (2) identify the processes which govern Antarctic change and feed back around the globe; (3) improve our ability to model past changes in Antarctica; and (4)document past change to predict future change in Antarctica. Subglacial Antarctic Lake Environments (SALE) promotes, facilitates, and champions cooperation and collaboration in the exploration and study of subglacial environments in Antarctica. SALE intends to understand the complex interplay of biological, geological, chemical, glaciological, and physical processes within subglacial lake environments through coordinated international research teams. Evolution and Biodiversity in the Antarctic (EBA) will use a suite of modern techniques and interdisciplinary approaches, to explore the evolutionary history of selected modern Antarctic biota, examine how modern biological diversity in the Antarctic influences the way present-day ecosystems function, and thereby predict how the biota may respond to future environmental change. Antarctica and the Global Climate System (AGCS) will investigate the nature of the atmospheric and oceanic linkages between the climate of the Antarctic and the rest of the Earth system, and the mechanisms involved therein. A combination of modern instrumented records of atmospheric and oceanic conditions, and the climate signals held within ice cores will be used to understand past and future climate

  4. Denitrification in the Antarctic stratosphere

    Science.gov (United States)

    Salawitch, R. J.; Gobbi, G. P.; Wofsy, S. C.; Mcelroy, M. B.

    1989-01-01

    Rapid loss of ozone over Antarctica in spring requires that the abundance of gaseous nitric acid be very low. Precipitation of particulate nitric acid has been assumed to occur in association with large ice crystals, requiring significant removal of H2O and temperatures well below the frost point. However, stratospheric clouds exhibit a bimodal size distribution in the Antarctic atmosphere, with most of the nitrate concentrated in particles with radii of 1 micron or greater. It is argued here that the bimodal size distribution sets the stage for efficient denitrification, with nitrate particles either falling on their own or serving as nuclei for the condensation of ice. Denitrification can therefore occur without significant dehydration, and it is unnecessary for temperatures to drop significantly below the frost point.

  5. Role of the meiobenthos in Antarctic ecosystems

    OpenAIRE

    Vanhove, S.; Wittoeck, J; Beghyn, M.; Van Gansbeke, D.; Van Kenhove, A.; Coomans, A.; Vincx, M.

    1997-01-01

    To date meiobenthic research remained a big white spot in the systematic-ecological work on Antarctic zoobenthos. Therefore the relative importance of the meiofauna (organisms within the size range of 38-1000µm) in the Antarctic benthic community has been assessed by a combined field ecology and experimental approach. This was done in two contrasting conditions, e.g. the deep sea and low subtidal, where as to the depth of the water column the benthic characteristics were, respectively, indire...

  6. Characterising Antarctic and Southern Ocean Lithosphere with Magnetic and Gravity Imaging of East Antarctic Rift Systems

    Science.gov (United States)

    Vaughan, A. P.; Kusznir, N. J.; Ferraccioli, F.; Jordan, T. A.; Purucker, M. E.; Golynsky, A. V.; Rogozhina, I.

    2012-12-01

    East Antarctica will identify the plate-scale geometry of zones of crustal and lithospheric thinning; 4) understanding when and how East Antarctica acquired its thick crust and high elevation, and why it is so thick and elevated, will place new constraints on models of Cenozoic ice sheet formation and stability. The crustal thickness map for East Antarctica will make it possible to produce a multi-dataset-based geothermal heatflux map for the continent. Estimating the heat flux in the Gamburtsev Subglacial Mountains (GSM) region is particularly critical because: 1) The GSM likely acted as key nucleation point for the East Antarctic Ice Sheet (EAIS); 2) the region may contain the oldest ice of the EAIS - a prime target for future ice core drilling; 3) geothermal heat flux is important to understand proposed ice accretion at the base of the EAIS in the GSM and its links to sub-ice hydrology; 4) an integrated multi-dataset-based geothermal heatflux model for East Antarctica will resolve the wide range of estimates previously published using single datasets.

  7. The safety band of Antarctic ice shelves

    Science.gov (United States)

    Fürst, Johannes Jakob; Durand, Gaël; Gillet-Chaulet, Fabien; Tavard, Laure; Rankl, Melanie; Braun, Matthias; Gagliardini, Olivier

    2016-05-01

    The floating ice shelves along the seaboard of the Antarctic ice sheet restrain the outflow of upstream grounded ice. Removal of these ice shelves, as shown by past ice-shelf recession and break-up, accelerates the outflow, which adds to sea-level rise. A key question in predicting future outflow is to quantify the extent of calving that might precondition other dynamic consequences and lead to loss of ice-shelf restraint. Here we delineate frontal areas that we label as `passive shelf ice’ and that can be removed without major dynamic implications, with contrasting results across the continent. The ice shelves in the Amundsen and Bellingshausen seas have limited or almost no `passive’ portion, which implies that further retreat of current ice-shelf fronts will yield important dynamic consequences. This region is particularly vulnerable as ice shelves have been thinning at high rates for two decades and as upstream grounded ice rests on a backward sloping bed, a precondition to marine ice-sheet instability. In contrast to these ice shelves, Larsen C Ice Shelf, in the Weddell Sea, exhibits a large `passive’ frontal area, suggesting that the imminent calving of a vast tabular iceberg will be unlikely to instantly produce much dynamic change.

  8. Mercury accumulation in sediments and seabird feathers from the Antarctic Peninsula

    International Nuclear Information System (INIS)

    Highlights: • We assessed mercury bioaccumulation in seabirds in the Antarctic Peninsula. • Levels of Hg were higher in gentoo penguins & brown skuas than chinstrap penguins. • Mercury BMF in the brown skua/penguins relationship was higher than 1. • Long-range environmental transport is the likely mercury route in Antarctic. - Abstract: In an effort to assess the impact of mercury in the Antarctic Peninsula, we conducted ecotoxicological research in this region during the summer of 2012 and 2013. The objectives were to assess: (a) mercury levels in sediment samples; (b) mercury accumulation in Antarctic seabird feathers: Catharacta lonnbergi (brown skua), Pygoscelis papua (gentoo penguin) and Pygoscelis antarctica (chinstrap penguin); and (c) biomagnification (BMF predator/prey) and biota sediment accumulation (BSAF skuas/sediment) factors. Mercury concentrations in sediment were relatively low. Mercury concentrations were significantly higher in brown skuas and gentoo penguins than in chinstrap penguins (2012), and significantly higher in brown skuas than in both penguins (2013). BMF indicated 2–7.5 times greater mercury levels in brown skuas than in penguins. BSAF values suggested an apparent temporal decrease of 18.2% of this ratio from 2012 to 2013. Long-range environmental transport is the likely route of entry of mercury into the Antarctic Peninsula

  9. Impacts of the north and tropical Atlantic Ocean on the Antarctic Peninsula and sea ice.

    Science.gov (United States)

    Li, Xichen; Holland, David M; Gerber, Edwin P; Yoo, Changhyun

    2014-01-23

    In recent decades, Antarctica has experienced pronounced climate changes. The Antarctic Peninsula exhibited the strongest warming of any region on the planet, causing rapid changes in land ice. Additionally, in contrast to the sea-ice decline over the Arctic, Antarctic sea ice has not declined, but has instead undergone a perplexing redistribution. Antarctic climate is influenced by, among other factors, changes in radiative forcing and remote Pacific climate variability, but none explains the observed Antarctic Peninsula warming or the sea-ice redistribution in austral winter. However, in the north and tropical Atlantic Ocean, the Atlantic Multidecadal Oscillation (a leading mode of sea surface temperature variability) has been overlooked in this context. Here we show that sea surface warming related to the Atlantic Multidecadal Oscillation reduces the surface pressure in the Amundsen Sea and contributes to the observed dipole-like sea-ice redistribution between the Ross and Amundsen-Bellingshausen-Weddell seas and to the Antarctic Peninsula warming. Support for these findings comes from analysis of observational and reanalysis data, and independently from both comprehensive and idealized atmospheric model simulations. We suggest that the north and tropical Atlantic is important for projections of future climate change in Antarctica, and has the potential to affect the global thermohaline circulation and sea-level change. PMID:24451542

  10. Development of a new generation gravity map of Antarctica: ADGRAV Antarctic Digital Gravity Synthesis

    Directory of Open Access Journals (Sweden)

    R. A. Arko

    1999-06-01

    Full Text Available The U.S. National Science Foundation (NSF has agreed to support the development of a new generation gravity map of Antarctica (ADGRAV - Antarctic Digital Gravity Synthesis, funding the development of a web based access tool. The goal of this project is the creation of an on-line Antarctic gravity database which will facilitate access to improved high resolution satellite gravity models, in conjunction with shipboard, airborne, and land based gravity measurements for the continental regions. This database will complement parallel projects underway to develop new continental bedrock (BEDMAP and magnetic (ADMAP maps of Antarctica.

  11. Subsurface imaging reveals a confined aquifer beneath an ice-sealed Antarctic lake

    DEFF Research Database (Denmark)

    Dugan, H. A.; Doran, P. T.; Tulaczyk, S.;

    2015-01-01

    Liquid water oases are rare under extreme cold desert conditions found in the Antarctic McMurdo Dry Valleys. Here we report geophysical results that indicate that Lake Vida, one of the largest lakes in the region, is nearly frozen and underlain by widespread cryoconcentrated brine. A ground penet...

  12. Field research on the effects of UV-B filters on terrestrial Antarctic vegetation

    NARCIS (Netherlands)

    Huiskes, A.H.L.; Lud, D.; Moerdijk-Poortvliet, T.C.W.

    2001-01-01

    Patches of vegetation of six common species growing on Leonie Island (67 degrees 35' S, 68 degrees 20' W), Antarctic Peninsula region were covered with either UV-B transparent perspex screens or UV-B absorbing screens. Uncovered plots served as a control. Temperature and relative humidity were monit

  13. Spatially Extensive Standardized Surveys Reveal Widespread, Multi-Decadal Increase in East Antarctic Adélie Penguin Populations

    Science.gov (United States)

    Southwell, Colin; Emmerson, Louise; McKinlay, John; Newbery, Kym; Takahashi, Akinori; Kato, Akiko; Barbraud, Christophe; DeLord, Karine; Weimerskirch, Henri

    2015-01-01

    Seabirds are considered to be useful and practical indicators of the state of marine ecosystems because they integrate across changes in the lower trophic levels and the physical environment. Signals from this key group of species can indicate broad scale impacts or response to environmental change. Recent studies of penguin populations, the most commonly abundant Antarctic seabirds in the west Antarctic Peninsula and western Ross Sea, have demonstrated that physical changes in Antarctic marine environments have profound effects on biota at high trophic levels. Large populations of the circumpolar-breeding Adélie penguin occur in East Antarctica, but direct, standardized population data across much of this vast coastline have been more limited than in other Antarctic regions. We combine extensive new population survey data, new population estimation methods, and re-interpreted historical survey data to assess decadal-scale change in East Antarctic Adélie penguin breeding populations. We show that, in contrast to the west Antarctic Peninsula and western Ross Sea where breeding populations have decreased or shown variable trends over the last 30 years, East Antarctic regional populations have almost doubled in abundance since the 1980’s and have been increasing since the earliest counts in the 1960’s. The population changes are associated with five-year lagged changes in the physical environment, suggesting that the changing environment impacts primarily on the pre-breeding age classes. East Antarctic marine ecosystems have been subject to a number of changes over the last 50 years which may have influenced Adélie penguin population growth, including decadal-scale climate variation, an inferred mid-20th century sea-ice contraction, and early-to-mid 20th century exploitation of fish and whale populations. PMID:26488299

  14. Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea-ice

    Directory of Open Access Journals (Sweden)

    R. S. Humphries

    2015-10-01

    Full Text Available The effect of aerosols on clouds and their radiative properties is one of the largest uncertainties in our understanding of radiative forcing. A recent study has concluded that better characterisation of pristine, natural aerosol processes leads to the largest reduction in these uncertainties. Antarctica, being far from anthropogenic activities, is an ideal location for the study of natural aerosol processes. Aerosol measurements in Antarctica are often limited to boundary layer air-masses at spatially sparse coastal and continental research stations, with only a handful of studies in the sea ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the ice-breaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3 concentrations exhibited a five-fold increase moving across the Polar Front, with mean Polar Cell concentrations of 1130 cm−3 – higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air-masses quickly from the free-troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea ice boundary layer air-masses travelled equator-ward into the low albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei where, after growth, may potentially impact on the region's radiative balance. The high aerosol

  15. Comparative roles of upwelling and glacial iron sources in Ryder Bay, coastal western Antarctic Peninsula

    OpenAIRE

    Annett, Amber; Skiba, Marta; Henley, Sian; Venables, Hugh J.; Meredith, Michael P.; Statham, Peter; Ganeshram, Raja

    2015-01-01

    Iron (Fe) is an essential micronutrient for phytoplankton, and is scarce in many regions including the open Southern Ocean. The western Antarctic Peninsula (WAP), an important source region of Fe to the wider Southern Ocean, is also the fastest warming region of the Southern Hemisphere. The relative importance of glacial versus marine Fe sources is currently poorly constrained, hindering projections of how changing oceanic circulation, productivity, and glacial dynamics may affect the balance...

  16. Health aspects of Antarctic tourism.

    Science.gov (United States)

    Prociv, P

    1998-12-01

    Increasing numbers of seaborne tourists are visiting Antarctica, with most coming from the United States (3503 in 1996-97), Germany (777), and Australia (680; cf. 356 in 1994-95 and 410 in 1995-96). The impression among travel medicine clinicians is that, each year, more prospective travelers seek advice about the health demands of this type of adventure, mostly relating to fitness for travel, exposure to extreme cold, hazards in ice and snow, and other potential health risks. This is a recent phenomenon. While a regular shipping service had been established between the Falklands and the subantarctic islands of South Georgia and the South Shetlands by 1924, the first documented tourists accompanied an Argentine expedition to the South Orkneys in 1933.1 Commercial airline flights over these islands and the Antarctic Peninsula began in 1956, from Chile, and recreational cruises to the Peninsula began in 1958. Tourist numbers subsequently grew slowly, for what was clearly an exclusive and very expensive undertaking, with few ships available for these hazardous voyages. From 1957 to 1993, 37,000 tourists visited by sea, most seeing only the Peninsula.2 The dramatic recent growth in numbers is a consequence of the collapse of the Soviet Union. The small fleet of ice-strengthened research vessels and working icebreakers, which was made redundant by withdrawal of central government support from isolated communities and military activities along the northern coast of Siberia (and from Antarctic research bases), now accounts for the bulk of charter-cruise tourism to Antarctica, at competitive prices. According to the International Association of Antarctica Tour Operators,3 7322 people traveled to Antarctica on commercially organized voyages in the 1996-97 season, and a record 10,000 shipborne visitors were expected for the 1997-98 season (November-March), traveling mainly from South America to the Peninsula on 15 ice-reinforced vessels, each carrying between 36 and 180

  17. 76 FR 9849 - Comprehensive Environmental Evaluations for Antarctic Activities

    Science.gov (United States)

    2011-02-22

    .... SUPPLEMENTARY INFORMATION: Article 3 of Annex I to the Protocol on Environmental Protection to the Antarctic... Comprehensive Environmental Evaluations for Antarctic Activities SUMMARY: The Department of State gives notice of the availability of two draft Comprehensive Environmental Evaluations (CEEs) for...

  18. ARM West Antarctic Radiation Experiment (AWARE) Science Plan

    Energy Technology Data Exchange (ETDEWEB)

    Lubin, D [National Science Foundation; Bromwich, DH [Ohio State University; Russell, LM [Scripps Institution of Oceanography; Verlinde, J [The Pennsylvania State University; Vogelmann, AM [Brookhaven National Laboratory

    2015-10-01

    West Antarctica is one of the most rapidly warming regions on Earth, and this warming is closely connected with global sea level rise. The discovery of rapid climate change on the West Antarctic Ice Sheet (WAIS) has challenged previous explanations of Antarctic climate change that focused on strengthening of circumpolar westerlies in response to the positive polarity trend in the Southern Annular Mode. West Antarctic warming does not yet have a comprehensive explanation: dynamical mechanisms may vary from one season to the next, and these mechanisms very likely involve complex teleconnections with subtropical and tropical latitudes. The prime motivation for this proposal is that there has been no substantial atmospheric science or climatological field work on West Antarctica since the 1957 International Geophysical Year and that research continued for only a few years. Direct meteorological information on the WAIS has been limited to a few automatic weather stations for several decades, yet satellite imagery and meteorological reanalyses indicate that West Antarctica is highly susceptible to advection of warm and moist maritime air with related cloud cover, depending on the location and strength of low pressure cells in the Amundsen, Ross, and Bellingshausen Seas. There is a need to quantify the role of these changing air masses on the surface energy balance, including all surface energy components and cloud-radiative forcing. More generally, global climate model simulations are known to perform poorly over the Antarctic and Southern Oceans, and the marked scarcity of cloud information at southern high latitudes has so far inhibited significant progress. Fortunately, McMurdo Station, where the Atmospheric Radiation Measurement Facility’s (ARM’s) most advanced cloud and aerosol instrumentation is situated, has a meteorological relationship with the WAIS via circulation patterns in the Ross and Amundsen Seas. We can therefore gather sophisticated data with cloud

  19. Study on ecological structures of coastal lakes in Antarctic continent

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Coastal region on the Antarctic continent, where it is under the influences both of ocean and ice sheet, as well as frequent human activities, could be considered as a fragile zone in Antarctic ecological environment. There are many lakes in coastal region, showing much differences from each other in physical-chemical features because of individual evolutionary history in their geographical environments, and suffering from different outside factors, such as climate changes and precipitation. Thus, it results in respective biological distribution and ecological structure in lakes. The present paper reports the results from the studies of chemical components, species distributions and community structures, which mainly consisted of planktons in lakes in the Vestfold Hills (68°38'S, 78°06'E), and the Larsemann Hills (69°30'S, 76°20'E), East Antarctica. It also treats the biological diversities and nutrient relationships of these different types of lakes. So as to provide more scientific basis for monitoring of climate changes and environmental protection in Antarctica.

  20. Antarctic winter mercury and ozone depletion events over sea ice

    Science.gov (United States)

    Nerentorp Mastromonaco, M.; Gårdfeldt, K.; Jourdain, B.; Abrahamsson, K.; Granfors, A.; Ahnoff, M.; Dommergue, A.; Méjean, G.; Jacobi, H.-W.

    2016-03-01

    During atmospheric mercury and ozone depletion events in the springtime in polar regions gaseous elemental mercury and ozone undergo rapid declines. Mercury is quickly transformed into oxidation products, which are subsequently removed by deposition. Here we show that such events also occur during Antarctic winter over sea ice areas, leading to additional deposition of mercury. Over four months in the Weddell Sea we measured gaseous elemental, oxidized, and particulate-bound mercury, as well as ozone in the troposphere and total and elemental mercury concentrations in snow, demonstrating a series of depletion and deposition events between July and September. The winter depletions in July were characterized by stronger correlations between mercury and ozone and larger formation of particulate-bound mercury in air compared to later spring events. It appears that light at large solar zenith angles is sufficient to initiate the photolytic formation of halogen radicals. We also propose a dark mechanism that could explain observed events in air masses coming from dark regions. Br2 that could be the main actor in dark conditions was possibly formed in high concentrations in the marine boundary layer in the dark. These high concentrations may also have caused the formation of high concentrations of CHBr3 and CH2I2 in the top layers of the Antarctic sea ice observed during winter. These new findings show that the extent of depletion events is larger than previously believed and that winter depletions result in additional deposition of mercury that could be transferred to marine and terrestrial ecosystems.

  1. Stratospheric column NO2 measurements from three Antarctic sites

    Science.gov (United States)

    Keys, J. G.; Johnston, P. V.

    1988-01-01

    The significance of stratospheric odd-nitrogen compounds in Antarctic ozone depletion studies has prompted an increase in Antarctic activities. Although several species are being studied, work has concentrated on the acquisition of NO2 data. Ground-based measurements of stratospheric column NO2 have been made at Arrival Heights, Antarctica, since spring 1982, with some gaps in the data base. Additional data has been acquired since February 1986 at Pole Station and Halley Bay, thus providing a chain of stations across the continent. The technique used is that of absorption spectroscopy in several wavelength regions, although here only those measurements are reported in the 430 to 450 nm region where strongly structured absorption been determined experimentally. However, theory features due to NO2 are identified in scattered sunlight in the zenith sky. Operation of a moon-tracking system at Arrival Heights has provided some additional data during the polar night. Previous analyses have shown that the NO2 column observed from the ground is strongly influenced by the season, and by the location of the site with respect to that of the polar vortex. The column amount correlates strongly with stratospheric temperature at about 70 mbar. The present data set further illustrates these features, and demonstrates both the strengths and qualifications apparent in the technique.

  2. Genetic differentiation in the circum—Antarctic sea spider Nymphon australe (Pycnogonida; Nymphonidae)

    Science.gov (United States)

    Arango, Claudia P.; Soler-Membrives, Anna; Miller, Karen J.

    2011-03-01

    Nymphon australe Hodgson 1902 is the most abundant species of sea spiders in the Southern Ocean. The species is recognised as highly morphologically variable, circumpolar and eurybathic—which is surprising given that sea spiders lack a planktonic stage; the fertilised eggs and larvae remain attached to the ovigers of the father, and consequently have limited dispersal capacity. In this study, we investigate the genetic structure of N. australe populations around Antarctica, confronting the apparent limited dispersal ability with its recognised circumpolarity. Here we analyse mitochondrial DNA of specimens from Antarctic Peninsula, Weddell Sea and East Antarctica to determine if they represent populations of the widespread N. australe — or instead we can recognise cryptic species - and how genetically different they are. Both CO1 and 16S sequence data produced single haplotype networks for N. australe from all three Antarctic locations without indication of cryptic speciation. However, we found strong phylogeographic structure among the three Antarctic locations based on CO1 data. There was only a single shared haplotype between the Antarctic Peninsula and the East Antarctica locations, and all three regions were significantly subdivided from each other ( FST=0.28, ppopulations of N. australe separated by 10-100 s of km ( FST=0.07-0.22, pspiders life history traits indicating a limited dispersal capability. We conclude N. australe represents a single circum-Antarctic species that, despite its limited dispersal abilities, has successfully colonised large parts of the Antarctic marine ecosystem through geological history. However, clear genetic differences among and within locations indicate contemporary gene flow is limited, and that populations of N. australe around Antarctica are effectively isolated.

  3. Variability of Antarctic Sea Ice 1979-1998

    Science.gov (United States)

    Zwally, H. Jay; Comiso, Josefino C.; Parkinson, Claire L.; Cavalieri, Donald J.; Gloersen, Per; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    The principal characteristics of the variability of Antarctic sea ice cover as previously described from satellite passive-microwave observations are also evident in a systematically-calibrated and analyzed data set for 20.2 years (1979-1998). The total Antarctic sea ice extent (concentration > 15 %) increased by 13,440 +/- 4180 sq km/year (+1.18 +/- 0.37%/decade). The area of sea ice within the extent boundary increased by 16,960 +/- 3,840 sq km/year (+1.96 +/- 0.44%/decade). Regionally, the trends in extent are positive in the Weddell Sea (1.5 +/- 0.9%/decade), Pacific Ocean (2.4 +/- 1.4%/decade), and Ross (6.9 +/- 1.1 %/decade) sectors, slightly negative in the Indian Ocean (-1.5 +/- 1.8%/decade, and strongly negative in the Bellingshausen-Amundsen Seas sector (-9.5 +/- 1.5%/decade). For the entire ice pack, small ice increases occur in all seasons with the largest increase during autumn. On a regional basis, the trends differ season to season. During summer and fall, the trends are positive or near zero in all sectors except the Bellingshausen-Amundsen Seas sector. During winter and spring, the trends are negative or near zero in all sectors except the Ross Sea, which has positive trends in all seasons. Components of interannual variability with periods of about 3 to 5 years are regionally large, but tend to counterbalance each other in the total ice pack. The interannual variability of the annual mean sea-ice extent is only 1.6% overall, compared to 5% to 9% in each of five regional sectors. Analysis of the relation between regional sea ice extents and spatially-averaged surface temperatures over the ice pack gives an overall sensitivity between winter ice cover and temperature of -0.7% change in sea ice extent per K. For summer, some regional ice extents vary positively with temperature and others negatively. The observed increase in Antarctic sea ice cover is counter to the observed decreases in the Arctic. It is also qualitatively consistent with the

  4. The Antarctic cryptoendolithic ecosystem - Relevance to exobiology

    Science.gov (United States)

    Friedmann, E. I.; Ocampo-Friedmann, R.

    1984-01-01

    Cryptoendolithic microorganisms in the Antarctic desert live inside porous sandstone rocks, protected by a thin rock crust. While the rock surface is abiotic, the microclimate inside the rock is comparatively mild. These organisms may have descended from early, pre-glaciation Antarctic life forms and thus may represent the last outpost of life in a gradually deteriorating environment. Assuming that life once arose on Mars, it is conceivable that, following the loss of water, the last of surviving organisms withdrew to similar insulated microenvironments. Because such microscopic pockets have little connection with the outside environment, their detection may be difficult. The chances that the Viking lander could sample cryptoendolithic microorganisms in the Antarctic desert would be infinitesimal.

  5. Model studies of the effects of global warming and Antarctic sea ice changes on Antarctic and global climates

    International Nuclear Information System (INIS)

    The authors discuss the results obtained in three experiments by changing the global ocean temperatures and the concentration and distribution of Antarctic sea ice in a General Circulation Model of July climate, with a view to determining the local and global impacts of Antarctic sea ice variations alone, as distinct with those coupled with global scale temperature changes which may be associated with global warming. In all cases there were significant changes in the upward flux of sensible heat over the sea ice zone associated with the reductions of sea ice. The response of weaker westerlies between 40 and 65 degree S was common to all three experiments. Their analyses suggest that a significant proportion of this is a response to the change in sea ice concentration alone. (Not surprisingly, further north of this region most of the changes induced in the wind structure in the global forcing experiment can be seen as due unambiguously to the differential changes in ocean temperatures.). This weakening of the westerlies means there is less mechanical forcing of the ocean in this region. From this they suggest that when consideration is given to the possible impact of feedbacks not considered in these experiments, sea ice changes alone, and particularly those in the Southern Hemisphere, have the potential to induce changes on a hemispheric scale

  6. Spatial and temporal characteristics of the little ice age: The Antarctic ice core record

    International Nuclear Information System (INIS)

    Recently, ice core records from both hemispheres, in conjunction with other proxy records (e.g., tree rings, speleothems and corals), have shown that the Little Ice Age (LIA) was spatially extensive, extending to the Antarctic. This paper examines the temporal and spatial characteristics of the dust and δ18O information from Antarctic ice cores. Substantial differences exist in the records. For example, a 550- year record of δ18O and dust concentrations from Siple Station, Antarctica suggests that warmer, less dusty conditions prevailed from A.D. 1600 to 1830. Alternately, dust and δ118O data from South Pole Station indicate that opposite conditions (e.g., cooler and more dusty) were prevalent during the LIA. Three additional Antarctic δ18O records are integrated with the Siple and South Pole histories for a more comprehensive picture of LIA conditions. The records provide additional support for the LIA temperature opposition between the Antarctic Peninsula region and East Antarctica. In addition, periods of strongest LIA cooling are not temporally synchronous over East Antarctica. These strong regional differences demonstrate that a suite of spatially distributed, high resolution ice core records will be necessary to characterize the LIA in Antarctica

  7. Mapping and Assessing Variability in the Antarctic Marginal Ice Zone, the Pack Ice and Coastal Polynyas

    Science.gov (United States)

    Stroeve, Julienne; Jenouvrier, Stephanie

    2016-04-01

    Sea ice variability within the marginal ice zone (MIZ) and polynyas plays an important role for phytoplankton productivity and krill abundance. Therefore mapping their spatial extent, seasonal and interannual variability is essential for understanding how current and future changes in these biological active regions may impact the Antarctic marine ecosystem. Knowledge of the distribution of different ice types to the total Antarctic sea ice cover may also help to shed light on the factors contributing towards recent expansion of the Antarctic ice cover in some regions and contraction in others. The long-term passive microwave satellite data record provides the longest and most consistent data record for assessing different ice types. However, estimates of the amount of MIZ, consolidated pack ice and polynyas depends strongly on what sea ice algorithm is used. This study uses two popular passive microwave sea ice algorithms, the NASA Team and Bootstrap to evaluate the distribution and variability in the MIZ, the consolidated pack ice and coastal polynyas. Results reveal the NASA Team algorithm has on average twice the MIZ and half the consolidated pack ice area as the Bootstrap algorithm. Polynya area is also larger in the NASA Team algorithm, and the timing of maximum polynya area may differ by as much as 5 months between algorithms. These differences lead to different relationships between sea ice characteristics and biological processes, as illustrated here with the breeding success of an Antarctic seabird.

  8. Comparative mesocosm study of biostimulation efficiency in two different oil-amended sub-antarctic soils

    OpenAIRE

    Delille, Daniel; Coulon, Frederic

    2008-01-01

    Biological treatment has become increasingly popular as a remediation method for soils and groundwater contaminated with petroleum hydrocarbon, chlorinated solvents, and pesticides. Bioremediation has been considered for application in cold regions such as Arctic and sub-Arctic climates and Antarctica. Studies to date suggest that indigenous microbes suitable for bioremediation exist in soils in these regions. This paper reports on two case studies at the sub-Antarctic Kerguelen Island, in wh...

  9. Potential genesis and implications of calcium nitrate in Antarctic snow

    Science.gov (United States)

    Mahalinganathan, Kanthanathan; Thamban, Meloth

    2016-04-01

    Among the large variety of particulates in the atmosphere, calcic mineral dust particles have highly reactive surfaces that undergo heterogeneous reactions with atmospheric acids contiguously. The association between nssCa2+, an important proxy indicator of mineral dust, and NO3-, a dominant anion in the Antarctic snowpack, was analysed. A total of 41 snow cores ( ˜ 1 m each) that represent snow deposited during 2008-2009 were studied along coastal-inland transects from two different regions in East Antarctica - the Princess Elizabeth Land (PEL) and central Dronning Maud Land (cDML). Correlation statistics showed a strong association (at 99 % significance level) between NO3- and nssCa2+ at the near-coastal sections of both PEL (r = 0.74) and cDML (r = 0.82) transects. Similarly, a strong association between these ions was also observed in snow deposits at the inland sections of PEL (r = 0.73) and cDML (r = 0.84). Such systematic associations between nssCa2+ and NO3- are attributed to the interaction between calcic mineral dust and nitric acid in the atmosphere, leading to the formation of calcium nitrate (Ca(NO3)2) aerosol. Principal component analysis revealed common transport and depositional processes for nssCa2+ and NO3- both in PEL and cDML. Forward- and back-trajectory analyses using HYSPLIT model v. 4 revealed that southern South America (SSA) was an important dust-emitting source to the study region, aided by the westerlies. Particle size distribution showed that over 90 % of the dust was in the range < 4 µm, indicating that these dust particles reached the Antarctic region via long-range transport from the SSA region. We propose that the association between nssCa2+ and NO3- occurs during the long-range transport due to the formation of Ca(NO3)2 rather than to local neutralisation processes. However, the influence of local dust sources from the nunataks in cDML and the contribution of high sea salt in coastal PEL evidently mask such association in the

  10. Antarctic marine bacteria versus UV-B irradiation

    International Nuclear Information System (INIS)

    strains only six were not able to survive 10 hours UV-B irradiation. The most sensitive strains were isolated from habitats protected from UV radiation (krill stomach, sea ice). The additional experiment, showing the lethal effect of UV-B for bacteria, throws light on the importance of shadowed environmental niches for bacterial survival in regions of the highest UV irradiance. Total cell number did not change significantly when exposed to UV-B radiation for 10h while without UV bacterial number increased by 27% during this period. The biovolume of strains used in this study which ranged from 0.14 to 13.7 (micro)m3 cell-1 also did not change significantly after 10 hours irradiation. Preliminary results show that the API 20NE test can be used to show changes in enzymatic abilities. Even 10 hours irradiation were not able to inhibit all enzymatic processes demonstrated by API 20NE system. The high variability in UV-B sensitivity of Antarctic bacteria may led to shifts from normal bacterial strains to more resistant. and thus to establish bacterial community adapted to life at risen UV-B level in the upper layer of Antarctic marine ecosystems. (author)

  11. Ocean forcing of glacier retreat in the western Antarctic Peninsula.

    Science.gov (United States)

    Cook, A J; Holland, P R; Meredith, M P; Murray, T; Luckman, A; Vaughan, D G

    2016-07-15

    In recent decades, hundreds of glaciers draining the Antarctic Peninsula (63° to 70°S) have undergone systematic and progressive change. These changes are widely attributed to rapid increases in regional surface air temperature, but it is now clear that this cannot be the sole driver. Here, we identify a strong correspondence between mid-depth ocean temperatures and glacier-front changes along the ~1000-kilometer western coastline. In the south, glaciers that terminate in warm Circumpolar Deep Water have undergone considerable retreat, whereas those in the far northwest, which terminate in cooler waters, have not. Furthermore, a mid-ocean warming since the 1990s in the south is coincident with widespread acceleration of glacier retreat. We conclude that changes in ocean-induced melting are the primary cause of retreat for glaciers in this region. PMID:27418507

  12. Why does the Antarctic Peninsula Warm in climate simulations?

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Xin; Hall, Alex [University of California, Department of Atmospheric and Oceanic Sciences, PO BOX 951565, Los Angeles, CA (United States); Boe, Julien [University of California, Department of Atmospheric and Oceanic Sciences, PO BOX 951565, Los Angeles, CA (United States); CNRS/CERFACS, URA 1875, Toulouse (France)

    2012-03-15

    The Antarctic Peninsula has warmed significantly since the 1950s. This pronounced and isolated warming trend is collectively captured by 29 twentieth-century climate hindcasts participating in the version 3 Coupled Model Intercomparison Project. To understand the factors driving warming trends in the hindcasts, we examine trends in Peninsula region's atmospheric heat budget in every simulation. We find that atmospheric latent heat release increases in nearly all hindcasts. These increases are generally anthropogenic in origin, and account for about 60% of the ensemble-mean warming trend in the Peninsula. They are driven primarily by well-understood features of the anthropogenic intensification of global hydrological cycle. As sea surface temperature increases, moisture contained in atmospheric flows increases. When such flows are forced to ascend the Peninsula's topography, enhanced local latent heat release results. The mechanism driving the warming of the Antarctic Peninsula is therefore clear in the models. Evidence for a similar mechanism operating in the real world is seen in the increasing snow accumulation rates inferred from ice cores drilled in the Peninsula. However, the relative importance of this mechanism and other processes previously identified as potentially causing the observed warming, such as the recent sea ice retreat in the Bellingshausen Sea, is difficult to assess. Thus the relevance of the simulated warming mechanism to the observed warming is unclear, in spite of its robustness in the models. (orig.)

  13. Contrasting Arctic and Antarctic sea ice temperatures

    Science.gov (United States)

    Vancoppenolle, Martin; Raphael, Marilyn; Rousset, Clément; Vivier, Frédéric; Moreau, Sébastien; Delille, Bruno; Tison, Jean-Louis

    2016-04-01

    Sea ice temperature affects the sea ice growth rate, heat content, permeability and habitability for ice algae. Large-scale simulations with NEMO-LIM suggest large ice temperature contrasts between the Arctic and the Antarctic sea ice. First, Antarctic sea ice proves generally warmer than in the Arctic, in particular during winter, where differences reach up to ~10°C. Second, the seasonality of temperature is different among the two hemispheres: Antarctic ice temperatures are 2-3°C higher in spring than they are in fall, whereas the opposite is true in the Arctic. These two key differences are supported by the available ice core and mass balance buoys temperature observations, and can be attributed to differences in air temperature and snow depth. As a result, the ice is found to be habitable and permeable over much larger areas and much earlier in late spring in the Antarctic as compared with the Arctic, which consequences on biogeochemical exchanges in the sea ice zone remain to be evaluated.

  14. Relevance of antarctic microbial ecosystems to exobiology

    Science.gov (United States)

    Mckay, Christopher P.

    1993-01-01

    Antarctic microbial ecosystems which provide biological and physical analogs that can be used in exobiology are studied. Since the access to extraterrestrial habitats is extremely difficult, terrestrial analogs represent the best opportunity for both formulation and preliminary testing of hypothesis about life. Antarctica, as one of few suitable environments on earth is considered to be a major locus of progress in exobiology.

  15. On-site and in situ remediation technologies applicable to petroleum hydrocarbon contaminated sites in the Antarctic and Arctic

    Directory of Open Access Journals (Sweden)

    Danielle Camenzuli

    2015-09-01

    Full Text Available Petroleum hydrocarbon contaminated sites, associated with the contemporary and legacy effects of human activities, remain a serious environmental problem in the Antarctic and Arctic. The management of contaminated sites in these regions is often confounded by the logistical, environmental, legislative and financial challenges associated with operating in polar environments. In response to the need for efficient and safe methods for managing contaminated sites, several technologies have been adapted for on-site or in situ application in these regions. This article reviews six technologies which are currently being adapted or developed for the remediation of petroleum hydrocarbon contaminated sites in the Antarctic and Arctic. Bioremediation, landfarming, biopiles, phytoremediation, electrokinetic remediation and permeable reactive barriers are reviewed and discussed with respect to their advantages, limitations and potential for the long-term management of soil and groundwater contaminated with petroleum hydrocarbons in the Antarctic and Arctic. Although these technologies demonstrate potential for application in the Antarctic and Arctic, their effectiveness is dependent on site-specific factors including terrain, soil moisture and temperature, freeze–thaw processes and the indigenous microbial population. The importance of detailed site assessment prior to on-site or in situ implementation is emphasized, and it is argued that coupling of technologies represents one strategy for effective, long-term management of petroleum hydrocarbon contaminated sites in the Antarctic and Arctic.

  16. Holocene Southern Ocean surface temperature variability west of the Antarctic Peninsula.

    Science.gov (United States)

    Shevenell, A E; Ingalls, A E; Domack, E W; Kelly, C

    2011-02-10

    The disintegration of ice shelves, reduced sea-ice and glacier extent, and shifting ecological zones observed around Antarctica highlight the impact of recent atmospheric and oceanic warming on the cryosphere. Observations and models suggest that oceanic and atmospheric temperature variations at Antarctica's margins affect global cryosphere stability, ocean circulation, sea levels and carbon cycling. In particular, recent climate changes on the Antarctic Peninsula have been dramatic, yet the Holocene climate variability of this region is largely unknown, limiting our ability to evaluate ongoing changes within the context of historical variability and underlying forcing mechanisms. Here we show that surface ocean temperatures at the continental margin of the western Antarctic Peninsula cooled by 3-4 °C over the past 12,000 years, tracking the Holocene decline of local (65° S) spring insolation. Our results, based on TEX(86) sea surface temperature (SST) proxy evidence from a marine sediment core, indicate the importance of regional summer duration as a driver of Antarctic seasonal sea-ice fluctuations. On millennial timescales, abrupt SST fluctuations of 2-4 °C coincide with globally recognized climate variability. Similarities between our SSTs, Southern Hemisphere westerly wind reconstructions and El Niño/Southern Oscillation variability indicate that present climate teleconnections between the tropical Pacific Ocean and the western Antarctic Peninsula strengthened late in the Holocene epoch. We conclude that during the Holocene, Southern Ocean temperatures at the western Antarctic Peninsula margin were tied to changes in the position of the westerlies, which have a critical role in global carbon cycling. PMID:21307939

  17. Late Miocene-Pliocene Asian monsoon intensification linked to Antarctic ice-sheet growth

    Science.gov (United States)

    Ao, Hong; Roberts, Andrew P.; Dekkers, Mark J.; Liu, Xiaodong; Rohling, Eelco J.; Shi, Zhengguo; An, Zhisheng; Zhao, Xiang

    2016-06-01

    Environmental conditions in one of Earth's most densely populated regions, East Asia, are dominated by the monsoon. While Quaternary monsoon variability is reasonably well understood, pre-Quaternary monsoon variability and dynamics remain enigmatic. In particular, little is known about potential relationships between northern hemispheric monsoon response and major Cenozoic changes in Antarctic ice cover. Here we document long-term East Asian summer monsoon (EASM) intensification through the Late Miocene-Pliocene (∼8.2 to 2.6 Ma), and attribute this to progressive Antarctic glaciation. Our new high-resolution magnetic records of long-term EASM intensification come from the Late Miocene-Pliocene Red Clay sequence on the Chinese Loess Plateau; we identify underlying mechanisms using a numerical climate-model simulation of EASM response to an idealized stepwise increase in Antarctic ice volume. We infer that progressive Antarctic glaciation caused intensification of the cross-equatorial pressure gradient between an atmospheric high-pressure cell over Australia and a low-pressure cell over mid-latitude East Asia, as well as intensification of the cross-equatorial sea-surface temperature (SST) gradient. These combined atmospheric and oceanic adjustments led to EASM intensification. Our findings offer a new and more global perspective on the controls behind long-term Asian monsoon evolution.

  18. Antarctic icebergs melt over the Southern Ocean : Climatology and impact on sea ice

    Science.gov (United States)

    Merino, Nacho; Le Sommer, Julien; Durand, Gael; Jourdain, Nicolas C.; Madec, Gurvan; Mathiot, Pierre; Tournadre, Jean

    2016-08-01

    Recent increase in Antarctic freshwater release to the Southern Ocean is suggested to contribute to change in water masses and sea ice. However, climate models differ in their representation of the freshwater sources. Recent improvements in altimetry-based detection of small icebergs and in estimates of the mass loss of Antarctica may help better constrain the values of Antarctic freshwater releases. We propose a model-based seasonal climatology of iceberg melt over the Southern Ocean using state-of-the-art observed glaciological estimates of the Antarctic mass loss. An improved version of a Lagrangian iceberg model is coupled with a global, eddy-permitting ocean/sea ice model and compared to small icebergs observations. Iceberg melt increases sea ice cover, about 10% in annual mean sea ice volume, and decreases sea surface temperature over most of the Southern Ocean, but with distinctive regional patterns. Our results underline the importance of improving the representation of Antarctic freshwater sources. This can be achieved by forcing ocean/sea ice models with a climatological iceberg fresh-water flux.

  19. Variability of Black Carbon Deposition to the East Antarctic Plateau, 1800-2000 AD

    Science.gov (United States)

    Bisiaux, M. M.; Edwards, R.; McConnell, J. R.; Albert, M. R.; Anschutz, H.; Neumann, T. A.; Isaksson, E.; Penner, J. E.

    2012-01-01

    Refractory black carbon aerosols (rBC) from biomass burning and fossil fuel combustion are deposited to the Antarctic ice sheet and preserve a history of emissions and long-range transport from low- and mid-latitudes. Antarctic ice core rBC records may thus provide information with respect to past combustion aerosol emissions and atmospheric circulation. Here, we present six East Antarctic ice core records of rBC concentrations and fluxes covering the last two centuries with approximately annual resolution (cal. yr. 1800 to 2000). The ice cores were drilled in disparate regions of the high East Antarctic ice sheet, at different elevations and net snow accumulation rates. Annual rBC concentrations were log-normally distributed and geometric means of annual concentrations ranged from 0.10 to 0.18 m cro-g/kg. Average rBC fluxes were determined over the time periods 1800 to 2000 and 1963 to 2000 and ranged from 3.4 to 15.5 m /a and 3.6 to 21.8 micro-g/sq m/a, respectively. Geometric mean concentrations spanning 1800 to 2000 increased linearly with elevation at a rate of 0.025 micro-g/kg/500 m. Spectral analysis of the records revealed significant decadal-scale variability, which at several sites was comparable to decadal ENSO variability.

  20. Phylogenetic Reassessment of Antarctic Tetillidae (Demospongiae, Tetractinellida) Reveals New Genera and Genetic Similarity among Morphologically Distinct Species.

    Science.gov (United States)

    Carella, Mirco; Agell, Gemma; Cárdenas, Paco; Uriz, Maria J

    2016-01-01

    Species of Tetillidae are distributed worldwide. However, some genera are unresolved and only a few genera and species of this family have been described from the Antarctic. The incorporation of 25 new COI and 18S sequences of Antarctic Tetillidae to those used recently for assessing the genera phylogeny, has allowed us to improve the resolution of some poorly resolved nodes and to confirm the monophyly of previously identified clades. Classical genera such as Craniella recovered their traditional diagnosis by moving the Antarctic Tetilla from Craniella, where they were placed in the previous family phylogeny, to Antarctotetilla gen. nov. The morphological re-examination of specimens used in the previous phylogeny and their comparison to the type material revealed misidentifications. The proposed monotypic new genus Levantinella had uncertain phylogenetic relationships depending on the gene partition used. Two more clades would require the inclusion of additional species to be formally established as new genera. The parsimony tree based on morphological characters and the secondary structure of the 18S (V4 region) almost completely matched the COI M1-M6 and the COI+18S concatenated phylogenies. Morphological synapomorphies have been identified for the genera proposed. New 15 28S (D3-D5) and 11 COI I3-M11 partitions were exclusively sequenced for the Antarctic species subset. Remarkably, species within the Antarctic genera Cinachyra (C. barbata and C. antarctica) and Antarctotetilla (A. leptoderma, A. grandis, and A. sagitta), which are clearly distinguishable morphologically, were not genetically differentiated with any of the markers assayed. Thus, as it has been reported for other Antarctic sponges, both the mitochondrial and nuclear partitions used did not differentiate species that were well characterized morphologically. Antarctic Tetillidae offers a rare example of genetically cryptic (with the traditional markers used for sponges), morphologically distinct

  1. Development and Applications of Dome A-DEM in Antarctic Ice Sheet

    Institute of Scientific and Technical Information of China (English)

    LIU Jiying; WEN Jiahong; WANG Yafeng; WANG Weili; Beata M CATHSO; Kenneth C JEZEK

    2007-01-01

    Dome A, the highest dome of East Antarctic Ice Sheet, is being an area focused by international Antarctic community after Chinese Antarctic Expedition finally reached there in 2005, and with the ongoing International Polar Year (IPY) during August 2007. In this paper two data processing methods are used together to generate two 100-m cell size digital elevation models (DEMs) of the Dome A region (Dome A-DEM) by using Cokriging method to interpolate the ICESat GLAS data, with Ihde-DEM as a constraint. It provides fundamental data to glaciological and geophysical investigation in this area. The Dome A-DEM was applied to determining the ice-sheet surface elevations and coordinates of the south and north summits, defining boundaries of basins and ice flowlines, deducing subglacial topography, and mapping surface slope and aspect in Dome A region. The DEM shows there are two (north and south) summits in Dome A region. The coordinate and the surface elevation of the highest point (the north summit) are 80°21'29.86"S, 77°21'50.29"E and 4092.71±1.43m, respectively. The ice thickness and sub-ice bedrock elevation at north summit are 2420m and 1672m, respectively. Dome A region contains four drainage basins that meet together near the south summit. Ice flowlines, slope and aspect in detail are also derived using the DEM.

  2. Global sediment thickness data set updated for the Australian-Antarctic Southern Ocean

    Science.gov (United States)

    Whittaker, Joanne M.; Goncharov, Alexey; Williams, Simon E.; Müller, R. Dietmar; Leitchenkov, German

    2013-08-01

    We present a new, 5 min sediment thickness grid for the Australian-Antarctic region (60°E-155°E, 30°S-70°S). New seismic reflection and refraction data have been used to add detail to the conjugate Australian and Antarctic margins and intervening ocean floor where regional sediment thickness patterns were poorly known previously. On the margins, sediment thickness estimates were computed from velocity-depth functions from sonobuoy/refraction velocity solutions ground-truthed against seismic reflection data. For the Southeast Indian Ridge abyssal plains, sediment thickness contours from Geli et al. (2007) were used. The new regional minimum sediment thickness grid was combined with the global National Geophysical Data Center (NGDC) sediment grid to create an updated global grid. Even using the minimum estimates, sediment accumulations on the extended Australian and Antarctic continental margins are 2 km thicker across large regions and up to 9 km thicker in the Ceduna Basin compared to the global NGDC compilation of sediment thickness data.

  3. Does Antarctic glaciation cool the world?

    Directory of Open Access Journals (Sweden)

    A. Goldner

    2012-07-01

    Full Text Available In this study we compare the simulated climatic impact of adding the Antarctic Ice Sheet to the "Greenhouse World" of the Eocene and removing the Antarctic Ice Sheet from the Modern world. The Modern surface temperature anomaly (ΔT induced by Antarctic Glaciation ranges from −1.22 to −0.18 K when CO2 is dropped from 2240 to 560 ppm, whereas the Eocene ΔT is nearly constant at −0.3 K. We calculate the climate sensitivity parameter S[Antarctica] which is defined as the change in surface temperature (ΔT divided by the change in radiative forcing (ΔQAntarctica imposed by prescribing the glacial properties of Antarctica. While the ΔT associated with the imposed Antarctic properties is relatively consistent across the Eocene cases, the radiative forcing is not. This leads to a wide range of S[Antarctica], with Eocene values systematically smaller than Modern.

    This differing temperature response in Eocene and Modern is partially due to the smaller surface area of the imposed forcing over Antarctica in the Eocene and partially due to the presence of strong positive sea-ice feedbacks in the Modern. The system's response is further mediated by differing shortwave cloud feedbacks which are large and of opposite sign operating in Modern and Eocene configurations. A negative cloud feedback warms much of the Earth's surface as a large ice sheet is introduced in Antarctica in the Eocene, whereas in the Modern this cloud feedback is positive and acts to enhance cooling introduced by adding an ice sheet. Because of the importance of cloud feedbacks in determining the final temperature sensitivity of the Antarctic Ice Sheet our results are likely to be model dependent. Nevertheless, these model results show that the radiative forcing and feedbacks induced by the Antarctic Ice Sheet did not significantly decrease global mean surface temperature across

  4. Tectonics of the Nazca-Antarctic plate boundary

    Science.gov (United States)

    Anderson-Fontana, Sandra; Larson, Roger L.; Engeln, Joseph F.; Lundgren, Paul; Stein, Seth

    1987-01-01

    A new bathymetric chart of part of the Chile transform system is constructed, based mainly on an R/V Endeavor survey from 100 deg W to its intersection with the East Ridge of the Juan Fernandez microplate. A generally continuous lineated trend can be followed through the entire region, with the transform valley being relatively narrow and well-defined from 109 deg W to approximately 104 deg 30 min W. The fracture zone then widens to the east, with at least two probable en echelon offsets to the south at 104 deg and 102 deg W. Six new strike-slip mechanisms along the Chile Transform and one normal fault mechanism near the northern end of the Chile Rise, inverted together with other plate-motion data from the eastern portion of the boundary, produce a new best-fit Euler pole for the Nazca-Antarctic plate pair, providing tighter constraints on the relative plate motions.

  5. Antarctic Wave Dynamics Mystery Discovered by Lidar, Radar and Imager

    Science.gov (United States)

    Chen, Cao; Chu, Xinzhao; Fong, Weichun; Lu, Xian; McDonald, Adrian J.; Pautet, Dominique; Taylor, Mike

    2016-06-01

    Since the start of the McMurdo Fe lidar campaign, largeamplitude (~±30 K), long-period (4 to 9 h) waves with upward energy propagating signatures are frequently observed in the MLT temperatures. Despite its frequent appearance, such type of wave was neither widely observed nor well understood in the past. At McMurdo (77.8°S, 166.7°E), the simultaneous observations of such waves using lidar, radar and airglow imager can provide 3-D intrinsic wave-propagation properties, which are greatly needed for understanding their sources and potential impacts. This study presents the first coincident observation of these 4-9 h waves by lidar, radar and airglow imager in the Antarctic mesopause region.

  6. Late Holocene tephrochronology of the northern Antarctic Peninsula

    Science.gov (United States)

    Björck, Svante; Sandgren, Per; Zale, Rolf

    1991-11-01

    Andesitic and basaltic andesitic tephra layers are abundant in Holocene deposits from the Antarctic Peninsula. Visually discernible tephra horizons occur in three lakes on Livingston Island. Tephra in two other lakes and in a moss bank on Elephant Island, with very low ash concentrations, were detected magnetically. Deception Island is the most likely volcanic source for the tephra. With direct 14C dating, age/depth curves, and cross-correlations at least 14 tephra horizons dating to between ca. 4700 and 250 yr B.P. were identified and now form the basis for a preliminary regional tephrochronology that will be a valuable dating tool for investigating the Holocene climatic history of Antarctica.

  7. Persistent organochlorines in high-Antarctic fish; Persistente chlororganische Verbindungen in hochantarktischen Fischen

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, S.

    1997-11-01

    24 chlorinated hydrocarbons from different classes (PCB, HCH, DDT, Chlordane, Hexachlorobenzene and Octachlorostyrene) were analyzed in four species of high-Antarctic fish (Aethotaxis mitopteryx, Pleuragramma antarcticum, Trematomus lepidorhinus, and Chinodraco myersi). The concentrations were in the order of 1 {mu}g/kg wet weight or 10 {mu}g/kg lipid weight, respectively. Highest concentrations were measured for HCB in all species. The species showed different distribution patterns for the organochlorines studied. Compared with concentrations in fish from other regions the organochlorine levels measured in Antarctic fish are rather low. It is unlikely that the burden of organochlorines will cause any toxic effects in high-Antarctic fish yet. Nevertheless, with regard to the sensitive Antarctic ecosystem, even small concentrations carry a high risk of harm for Antarctic life. Environmental pollution in Antarctica should be observed with a monitoring program using standardized methods. For this purpose, the fish species studied are very useful as bioindicators for organochlorine contamination. (orig.) [Deutsch] 24 persistente Chlorkohlenwasserstoffe verschiedener Schadstoffgruppen (PCB, HCH, DDT, Chlordan, Hexachlorbenzol und Octachlorstyrol) wurden in vier hochantarktischen Fischarten (Aethotaxis mitopteryx, Pleuragramma antarcticum, Trematomus lepidorhinus und Chionodraco myersi). Die Konzentrationen der nachgewiesenen Schadstoffe im Ganzfisch liegen jeweils in der Groessenordnung von 1 {mu}g/kg Feuchtgewicht bzw. 10 {mu}g/kg Lipidgewicht mit erheblichen Schwankungen je nach Schadstoff und Art. Die Spezies zeigen artspezifische Schadstoffverteilungsmuster. Die Konzentrationen sind gegenueber denen in Fischen aus Gebieten mit staerkerem zivilisatorischem Einfluss eher niedrig. Die Fremstoffbelastungen der hochantarktischen Fische fuehren wahrscheinlich noch nicht zu messbaren toxischen Effekten bei den Fischen. Dennoch geht von den Schadstoffen in Hinblick auf das

  8. Present-day and future Antarctic ice sheet climate and surface mass balance in the Community Earth System Model

    Science.gov (United States)

    Lenaerts, Jan T. M.; Vizcaino, Miren; Fyke, Jeremy; van Kampenhout, Leo; van den Broeke, Michiel R.

    2016-02-01

    We present climate and surface mass balance (SMB) of the Antarctic ice sheet (AIS) as simulated by the global, coupled ocean-atmosphere-land Community Earth System Model (CESM) with a horizontal resolution of ˜1° in the past, present and future (1850-2100). CESM correctly simulates present-day Antarctic sea ice extent, large-scale atmospheric circulation and near-surface climate, but fails to simulate the recent expansion of Antarctic sea ice. The present-day Antarctic ice sheet SMB equals 2280 ± 131 {Gt year^{-1}} , which concurs with existing independent estimates of AIS SMB. When forced by two CMIP5 climate change scenarios (high mitigation scenario RCP2.6 and high-emission scenario RCP8.5), CESM projects an increase of Antarctic ice sheet SMB of about 70 {Gt year^{-1}} per degree warming. This increase is driven by enhanced snowfall, which is partially counteracted by more surface melt and runoff along the ice sheet's edges. This intensifying hydrological cycle is predominantly driven by atmospheric warming, which increases (1) the moisture-carrying capacity of the atmosphere, (2) oceanic source region evaporation, and (3) summer AIS cloud liquid water content.

  9. Onset and role of the Antarctic Circumpolar Current

    OpenAIRE

    Barker, P. F.; Threshers Barn, Whitcott Keysett, Clun, Shropshire SY7 8QE, UK; Filippelli, G. M.; Department of Earth Sciences, Indiana University-Purdue University Indianapolis (IUPUI), Indianapolis, IN 46202-5132, USA; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Martin, E. E.; Department of Geological Sciences, University of Florida, Gainesville, FL 32611-2120, USA; Howard, D. S.; Department of Earth & Environmental Sciences, University of Rochester, Rochester, NY 14611, USA

    2007-01-01

    For some time, onset of the Antarctic Circumpolar Current (ACC) was considered to have caused or stabilised full Antarctic glaciation. Recently, however, the importance of the ACC in this role has been questioned. In order to understand the relationship between the ACC and Antarctic glaciation, and thence the importance of ocean circulation to palaeoclimate, we need to determine the development history of both processes. To this end, we summarise all published estimates of ACC ons...

  10. Relative Changes in Krill Abundance Inferred from Antarctic Fur Seal

    OpenAIRE

    Tao Huang; Liguang Sun; John Stark; Yuhong Wang; Zhongqi Cheng; Qichao Yang; Song Sun

    2011-01-01

    Antarctic krill Euphausia superba is a predominant species in the Southern Ocean, it is very sensitive to climate change, and it supports large stocks of fishes, seabirds, seals and whales in Antarctic marine ecosystems. Modern krill stocks have been estimated directly by net hauls and acoustic surveys; the historical krill density especially the long-term one in the Southern Ocean, however, is unknown. Here we inferred the relative krill population changes along the West Antarctic Peninsula ...

  11. Encouraging Advances Made by Chinese Scientists in Antarctic Research

    Institute of Scientific and Technical Information of China (English)

    Zhang Qingsong

    2003-01-01

    @@ Chinese scientists began involving in the Antarctic research in 1980. As the first step, some 40 Chinese scientists were sent to Antarctic stations of Australia and other countries during the period from 1980 to 1984. Then,China established two Antarctic stations of its own, and purchased an icebreaker, enabling China to carry on its own independent research program both on land and at sea.

  12. Geophysical Characteristics of the Australian-Antarctic Ridge

    Science.gov (United States)

    Kim, S. S.; Lin, J.; Park, S. H.; Choi, H.; Lee, S. M.

    2014-12-01

    Between 2011 and 2013, the Korea Polar Research Institute (KOPRI) conducted three consecutive geologic surveys at the little explored eastern ends of the Australian-Antarctic Ridge (AAR) to characterize the tectonics, geochemistry, and hydrothermal activity of this intermediate spreading system. Using the Korean icebreaker R/V Araon, the multi-disciplinary research team collected bathymetry, gravity, magnetics, and rock and water column samples. In addition, Miniature Autonomous Plume Recorders (MAPRs) were deployed at wax-core rock sampling sites to detect the presence of active hydrothermal vents. Here we present a detailed analysis of a 300-km-long supersegment of the AAR to quantify the spatial variations in ridge morphology and robust axial and off-axis volcanisms. The ridge axis morphology alternates between rift valleys and axial highs within relatively short ridge segments. To obtain a geological proxy for regional variations in magma supply, we calculated residual mantle Bouguer gravity anomalies (RMBA), gravity-derived crustal thickness, and residual topography for seven sub-segments. The results of the analyses revealed that the southern flank of the AAR is associated with shallower seafloor, more negative RMBA, thicker crust, and/or less dense mantle than the conjugate northern flank. Furthermore, this north-south asymmetry becomes more prominent toward the KR1 supersegment of the AAR. The axial topography of the KR1 supersegment exhibits a sharp transition from axial highs at the western end to rift valleys at the eastern end, with regions of axial highs being associated with more magma supply as indicated by more negative RMBA. We also compare and contrast the characteristics of the AAR supersegment with that of other ridges of intermediate spreading rates, including the Juan de Fuca Ridge, Galápagos Spreading Center, and Southeast Indian Ridge west of the Australian-Antarctic Discordance, to investigate the influence of ridge-hotspot interaction on

  13. Observationally constrained projections of Antarctic ice sheet instability

    Science.gov (United States)

    Edwards, Tamsin; Ritz, Catherine; Durand, Gael; Payne, Anthony; Peyaud, Vincent; Hindmarsh, Richard

    2015-04-01

    Large parts of the Antarctic ice sheet lie on bedrock below sea level and may be vulnerable to a positive feedback known as Marine Ice Sheet Instability (MISI), a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence MISI may be underway throughout the Amundsen Sea Embayment (ASE) of West Antarctica, induced by circulation of warm Circumpolar Deep Water. If this retreat is sustained the region could contribute up to 1-2 m to global mean sea level, and if triggered in other areas the potential contribution to sea level on centennial to millennial timescales could be two to three times greater. However, physically plausible projections of Antarctic MISI are challenging: numerical ice sheet models are too low in spatial resolution to resolve grounding line processes or else too computationally expensive to assess modelling uncertainties, and no dynamical models exist of the ocean-atmosphere-ice sheet system. Furthermore, previous numerical ice sheet model projections for Antarctica have not been calibrated with observations, which can reduce uncertainties. Here we estimate the probability of dynamic mass loss in the event of MISI under a medium climate scenario, assessing 16 modelling uncertainties and calibrating the projections with observed mass losses in the ASE from 1992-2011. We project losses of up to 30 cm sea level equivalent (SLE) by 2100 and 72 cm SLE by 2200 (95% credibility interval: CI). Our results are substantially lower than previous estimates. The ASE sustains substantial losses, 83% of the continental total by 2100 and 67% by 2200 (95% CI), but in other regions losses are limited by ice dynamical theory, observations, or a lack of projected triggers.

  14. The seasonal cycle of ocean-atmosphere CO2 Flux in Ryder Bay, West Antarctic Peninsula.

    OpenAIRE

    Legge, Oliver J.; Bakker, Dorothee C. E.; Johnson, Martin T.; Meredith, Michael P.; Venables, Hugh J.; Brown, Peter J.; Lee, Gareth A.

    2015-01-01

    Approximately 15 million km2 of the Southern Ocean is seasonally ice covered, yet the processes affecting carbon cycling and gas exchange in this climatically important region remain inadequately understood. Here, 3 years of dissolved inorganic carbon (DIC) measurements and carbon dioxide (CO2) fluxes from Ryder Bay on the west Antarctic Peninsula (WAP) are presented. During spring and summer, primary production in the surface ocean promotes atmospheric CO2 uptake. In winter, higher DIC, caus...

  15. Measurements beneath an Antarctic ice shelf using an autonomous underwater vehicle

    OpenAIRE

    Nicholls, K.W.; Abrahamsen, E.P.; Buck, J.J.H.; P. A. Dodd; Goldblatt, C.; Griffiths, G; K. J. Heywood; Hughes, N.E.; Kaletzky, A.; Lane-Serff, G.F.; McPhail, S.D.; Millard, N. W.; Oliver, K. I. C.; Perrett, J; Price, M. R.

    2006-01-01

    The cavities beneath Antarctic ice shelves are among the least studied regions of the World Ocean, yet they are sites of globally important water mass transformations. Here we report results from a mission beneath Fimbul Ice Shelf of an autonomous underwater vehicle. The data reveal a spatially complex oceanographic environment, an ice base with widely varying roughness, and a cavity periodically exposed to water with a temperature significantly above the surface freezing point. The result...

  16. Impacts of unusually high sea ice cover on Antarctic coastal benthic food web structure

    OpenAIRE

    Michel, Loïc; Dubois, Philippe; Eleaume,Marc; Fournier, Jérôme; Gallut, Cyril; Jane, Philip; Lepoint, Gilles

    2016-01-01

    Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice cover decrease, the sea ice cover of East Antarctica unexpectedly tends to increase, possibly in relation with changes in atmospheric circulation. Changes in sea ice cover are likely to influence benthic food web structure through modifications of benthic-pelagic coupling, disruption of benthic...

  17. Antarctic network of lamp-calibrated multichannel radiometers for continuous ozone and uv radiation data

    OpenAIRE

    Redondas, A.; Torres, C.; O. Meinander; K. Lakkala; R. García; E. Cuevas; Ochoa, H.; Deferrari, G.; Díaz, S.

    2008-01-01

    Three NILU-UV multichannel radiometers have been installed in 1999 at the Argentinian sites of Ushuaia (54S), Marambio (64S) and Belgrano-II (77S) in order to continuously monitor UV radiation, photosynthetically active radiation and total ozone. The measurements were established by INM, Spain in collaboration with FMI, Finland, DNA-IAA, Argentina and CADIC, Argentina to observe and characterize the spatial and temporal evolution of ozone and ultraviolet radiation in the Antarctic region. Spe...

  18. Sources and Levels of Ambient Ocean Sound near the Antarctic Peninsula

    OpenAIRE

    Dziak, Robert P.; Bohnenstiehl, DelWayne R.; Stafford, Kathleen M.; Haruyoshi Matsumoto; Minkyu Park; Won Sang Lee; Fowler, Matt J.; Tai-Kwan Lau; Haxel, Joseph H.; Mellinger, David K.

    2015-01-01

    Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (Antarctic Peninsula region) from 2005 to 2009 to record ambient ocean sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent feature of the ocean soundscape. Icequake activity peaks during austral summer and is minimum during winter, likely following freeze-thaw cycles. Iceberg grounding and rapi...

  19. Towards quantifying the contribution of the Antarctic ice sheet to global sea level change

    OpenAIRE

    van den Broeke, M. R.

    2006-01-01

    At present, the mass balance of the Antarctic Ice Sheet (AIS) and its contribution to global sea level change are poorly known. Current methods to determine AIS mass balance as well as the inherent uncertainties are discussed. Special emphasis is placed on the increasingly important role of regional atmospheric climate models, which can reduce the uncertainties in surface accumulation, the correction for the firn layer depth and density in ice thickness calculations and moreover help in inter...

  20. Terrestrial age dating of antarctic meteorites

    International Nuclear Information System (INIS)

    During the last three antarctic field seasons, US and Japanese teams have collected several thousand meteorites. The terrestrial age of these objects is of interest because such knowledge enables the setting of lower bounds on the lower age of the ice sheet, provides information about ice movement, and aids understanding of the accumulation mechanism of the meteorites. Terrestrial ages can be established by measuring the decay of radioactive species produced by bombardment of cosmic rays while the objects are in space. After entering the Earth's atmosphere the meteorites essentially are completely shielded from cosmic rays. The radioactive products that exist at saturation values in space then decay exponentially toward zero activity. By the end of 1980, data will be established on 150 to 200 selected samples. With that large a data base we should have a fairly clear picture of the terrestrial age distribution of antarctic meteorites

  1. Climate Change Impacts in the sub-Antarctic Islands Technical Report N.2 of ONERC; Impacts du changement climatique dans les iles subantarctiques. Rapport Technique N.2 de l'ONERC

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    Difficult to apprehend as a whole, the polar regions constitute the Arctic to the North, an ocean surrounded by emerged lands, and the Antarctic to the South, a continent bordered by the Austral Ocean where a belt of sub Antarctic islands lies. Climate change impacts on sub Antarctic islands are varied, direct and indirect: glacier retreat, more favourable conditions for introduced species, marine biodiversity modification, etc. This report discusses the French, British, Australian, South African and New Zealand sub Antarctic islands, the climatic evolutions and the resulting impacts, focused especially on biodiversity. The Observatoire National sur les Effets du Rechauffement Climatique and the International Polar Foundation have been joined in this endeavour by the French polar institute Paul-Emile Victor, the administration of the French Southern and Antarctic Lands (TAAF in French) and the International Union for the Conservation of Nature. (authors)

  2. The effect of environmental change on vascular plant and cryptogam communities from the Falkland Islands and the Maritime Antarctic

    NARCIS (Netherlands)

    Bokhorst, S.F.; Huiskes, A.H.L.; Convey, P.; Aerts, R.A.M.

    2007-01-01

    Antarctic terrestrial vegetation is subject to one of the most extreme climates on Earth. Currently, parts of Antarctica are one of the fastest warming regions on the planet. During 3 growing seasons, we investigated the effect of experimental warming on the diversity and abundance of coastal plant

  3. The experience of the Antarctic Seismic Data Library System (SDLS) as a hub for researchers in antarctic crustal studies.

    Science.gov (United States)

    Diviacco, Paolo; Wardell, Nigel

    2010-05-01

    The SDLS was created in April 1991 under the auspices of the Scientific Committee on Antarctic Research to provide open access to Antarctic multichannel seismic-reflection data (MCS) for use in cooperative research projects. The SDLS operates under the mandates of the Antarctic Treaty System, by which all institutions that collect MCS data in Antarctica must submit their MCS data to the SDLS. The SDLS has library branches worldwide at which researchers may view and study the MCS data. MCS data are submitted to the SDLS within 4 years of collection and remain in the library under SDLS guidelines until 8 years after collection. Thereafter, the data go to World Data Centers or equivalents for unrestricted use. The SDLS offers a clearing house, based at Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS) where data are processed when needed and georeferenced, so that the end user can be provided with usable, although basic, post-stack seismic sections. Re-processing of data is beyond the scope of the SDLS, so that if a researcher is interested in reviewing pre-stack data he/she must resort to the data owner. So far 228,000 km of seismic data have been made public in all sectors of the Antarctic region. To augment the concept of physical repositories where data can be accessed by researchers travelling to one of the branches or from where data could be copied to digital media and sent to users, in 2003 it was decided to develop a web interface where data could be searched for and accessed directly. At that moment no previous non-commercial experience was available in this data field, so that the system was designed from scratch. Several technologies were introduced, tested, and after a period of use, reviewed and tuned. Particular attention was devoted to the seismic data viewing facility, which was tailored to the needs of a community with specific practices and legacies. Seismic data are sensitive data that are very important for the E&P industry, so

  4. Meteorological observatory for Antarctic data collection; L`Osservatorio per l`acquisizione dei dati meteorologici in Antartide

    Energy Technology Data Exchange (ETDEWEB)

    Grigioni, P.; De silvestri, L. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dip. Ambiente; Della Vedova, A.M. [Istituto Nazionale di Geofisica, P.N.R.A., Rome (Italy)

    1996-12-31

    In the last years, a great number of automatic weather stations was installed in Antarctica, with the aim to examine closely the weather and climate of this region and to improve the coverage of measuring points on the Antarctic surface. In 1987 the Italian Antarctic Project started to set up a meteorological network, in an area not completely covered by other countries. Some of the activities performed by the meteorological observatory, concerning technical functions such as maintenance of the AWS`s and the execution of radio soundings, or relating to scientific purposes such as validation and elaboration of collected data, are exposed. Finally, some climatological considerations on the thermal behaviour of the Antarctic troposphere such as `coreless winter`, and on the wind field, including katabatic flows in North Victoria Land are described.

  5. Antarctic terrestrial ecosystems: responses to environmental change

    OpenAIRE

    Convey, Peter

    2006-01-01

    The consequences of climate change are exciting considerable concern worldwide. Parts of Antarctica are facing the most rapid rates of anthropogenic climate change currently seen on the planet. This paper sets out to introduce contemporary ecosystems of the Antarctic, and the factors that have influenced them and their biodiversity over evolutionary timescales. Contemporary climate change processes significant to terrestrial biota, and the biological consequences of these changes seen t...

  6. Isotopic heterogeneity of East Antarctic mantle

    International Nuclear Information System (INIS)

    Isotopic heterogeneity of deep garnet-bearing mantle xenolytes of East Antarctics is studied to analyze the mechanisms of geochemical heterogeneity occurrence in the Earth mantle. Analysis of isotope data for the system 143Nd/144Nd - Sm/Nd permitted ascertaining the time of the last thermal impact on the mantle material (108-35 bill. years) for certain nodules, which is close to the age of ultra base alkali magmatism intrusion

  7. Photosynthesis in Antarctic sea ice diatoms

    OpenAIRE

    Mock, Thomas

    2003-01-01

    This thesis was conducted to apply new techniques for measuring photosynthesis in Antarctic sea ice diatoms. A systematic approach of investigations was applied to obtain precise measurements of photosynthesis under natural conditions in the field from which questions were derived for further analysis in the laboratory. In situ measurements with the tracer 14C through the entire thickness of a young sea ice floe revealed that algae are able to actively assimilate dissolved inorganic carbon un...

  8. Oil Pollution in the Antarctic Terrestrial Environment

    OpenAIRE

    Hughes, Kevin; Stallwood, Bethan

    2006-01-01

    Fuel oil has been extensively relied upon as an energy source since the earliest discovery and exploration of Antarctica. During this time oil spills have occurred, particularly around established research stations, which have had a negative impact on the terrestrial environment. Recently developed bioremediative technology, using indigenous Antarctic hydrocarbon-degrading bacteria, may be used to assist in cleaning up existing oil-contaminated land

  9. PSEUDO MAGNETIC ANOMALIES IN THE ANTARCTIC SEA

    OpenAIRE

    マツモト, タケシ; カミヌマ, カツタダ; Takeshi, MATSUMOTO; Katsutada, Kaminuma

    1988-01-01

    Pseudo magnetic anomaly in the Antarctic Sea has been calculated using the gravity data derived from altimetric geoid. Comparison of the pseudo magnetic anomaly thus calculated with the theoretical magnetic anomaly predicted from topography has been made with respect to the large fracture zones composed of short-wavelength ridges and troughs in the Southeastern Pacific, which shows that these two anomalies coincide well with each other. Gravity anomaly calculated from topography only also coi...

  10. Tephrochronology : Methodology and correlations, Antarctic Peninsula Area

    OpenAIRE

    Molén, Mats

    2012-01-01

    Abstract Methods for tephrochronology are evaluated, in the following way: Lake sediments <500 years old from three small Antarctic lakes were analysed for identification of tephras. Subsamples were analysed for a) grain size, and identification and concentration of volcanogenic grains, b) identification of tephra horizons, c) element abundance by EPMA WDS/EDS and LA-ICP-MS, and d) possible correlations between lakes and volcanoes. Volcanogenic minerals and shards were found all through th...

  11. New and rare cephalopods from the Antarctic waters

    OpenAIRE

    Kubodera,Tsunemi/Okutani,Takeshi

    1986-01-01

    Three species of Antarctic cephalopods, Grimpoteuthis antarctica n. sp., male specimens of Megaleledone senoi TAKI and Gonatus antarcticus LONNBERG are described with some considerations to their systematic status.

  12. Measurements of 36Cl in Antarctic meteorites and Antarctic ice using a Van de Graaff accelerator

    International Nuclear Information System (INIS)

    Cosmic-ray produced 36Cl(tsub(1/2) = 3.0 X 105 years) has been measured in four Antarctic meteorites and one sample of Antarctic ice using a tandem Van de Graaff accelerator as an ultrasensitive mass spectrometer with the extremely low background level of 36Cl/Cl -16. Results from this ion counting technique (applied here to extraterrestrial materials for the first time) are used to support a two-stage irradiation model for the Yamato-7301and Allan Hills-76008 meteorites and to show a long terrestrial age (0.7 +- 0.1 m.y.) for Allan Hills-77002. Yamato-7304 has a terrestrial age of less than 0.1 m.y. The 36Cl content of the Antarctic ice sample from the Yamato Mountain area implies that the age of the ice cap at this site is less than one 36Cl half-life. (Auth.)

  13. Jun Jaegyu Volcano: A Recently Discovered Alkali Basalt Volcano in Antarctic Sound, Antarctica

    Science.gov (United States)

    Hatfield, A.; Bailey, D.; Domack, E.; Brachfeld, S.; Gilbert, R.; Ishman, S.; Krahmann, G.; Leventer, A.

    2004-12-01

    Jun Jaegyu is a young volcanic construct discovered in May 2004 by researchers aboard the National Science Foundation (NSF) vessel Laurence M. Gould (LMG04-04). The volcano is located on the Antarctic continental shelf in Antarctic Sound, approximately 9 km due north of the easternmost point of Andersson Island. Swath bathymetry (NBP01-07) indicates that the volcano stands 700 meters above the seafloor, yet remains 275 meters short of the ocean surface. The seamount lies along a northwest-southeast oriented fault scarp and contains at least 1.5 km3 of volcanic rock. Video recording of the volcano's surface revealed regions nearly devoid of submarine life. These areas are associated with a thermal anomaly of up to 0.052° C higher than the surrounding ocean water. A rock dredge collected ~13 kg of material, over 80% of which was fresh volcanic rock; the remainder was glacial IRD. These observations, along with reports by mariners of discolored water in this region of Antarctic Sound, suggest that the volcano has been recently active. The basalt samples are generally angular, glassy and vesicular. Preliminary petrographic observations indicate that plagioclase, olivine, and clinopyroxene are all present as phenocryst phases, and that small (tectonic setting of the region is complex, volcanism appears to be associated with active faults related to within-plate extension.

  14. Skip spawning as a reproductive strategy in Antarctic fish species: the Antarctic silverfish (Pleuragramma antarctica) case study

    OpenAIRE

    Eva Pisano; Stuart Hanchet; Marino Vacchi

    2015-01-01

    The Antarctic silverfish Pleuragramma antarctica (Notothenioidei, Nototheniidae) is the most abundant pelagic fish inhabiting the frigid Antarctic coastal waters. It plays relevant roles in the local ecosystems, where it is often considered a keystone species connecting lower and upper trophic levels within the coastal marine food web. Despite its ecological relevance, and although many aspects of the Antarctic silverfish biology have already been elucidated, knowledge on important components...

  15. Overview of mercury measurements in the Antarctic troposphere

    Directory of Open Access Journals (Sweden)

    A. Dommergue

    2010-04-01

    may be recycled. Therefore, the contribution of this unique reactivity occurring in polar atmospheres to the global budget of atmospheric mercury, and the role played by snow and ice surfaces of these regions, are important issues. This paper presents a review of atmospheric mercury studies conducted in the Antarctic troposphere, both at coastal locations and on the Antarctic Plateau since 1985. Our current understanding of atmospheric reactivity in this region is also presented.

  16. Overview of mercury measurements in the Antarctic troposphere

    Directory of Open Access Journals (Sweden)

    A. Dommergue

    2009-12-01

    contribution of this unique reactivity occurring in polar atmospheres to the global budget of atmospheric Hg and the role played by snow and ice surfaces of these regions are important issues. This paper presents a review of atmospheric mercury studies conducted in the Antarctic troposphere, both at coastal locations and on the Antarctic Plateau since 1985. Our current understanding of atmospheric reactivity in this region is also presented.

  17. Quality assurance of the solar UV network in the Antarctic

    Science.gov (United States)

    Lakkala, K.; Redondas, A.; Meinander, O.; Torres, C.; Koskela, T.; Cuevas, E.; Taalas, P.; Dahlback, A.; Deferrari, G.; Edvardsen, K.; Ochoa, H.

    2005-08-01

    Measuring ultraviolet radiation in the Antarctic region, where weather conditions are extremely challenging, is a demanding task. Proper quality control of the measurements and quality assurance of the data, which are the basis of all scientific use of data, has to be especially well planned and executed. In this paper we show the importance of proper quality assurance and describe the methods used to successfully operate the NILU-UV multichannel radiometers of the Antarctic network stations at Ushuaia, 54°S, and Marambio, 64°S. According to our experience, even though multichannel instruments are supposed to be rather stable as a function of time, severe drifts can occur in the sensitivity of the channels under these harsh conditions. During 2000-2003 the biggest drifts were 35%, both at Ushuaia and Marambio, with the sensitivity of the channels dropping at different rates. Without proper corrections in the data, this would have seriously affected the calculated UV dose rates. As part of the quality assurance of the network a traveling reference NILU-UV, which was found to be stable, was used to transfer the desired irradiance scale to the site NILU-UV data. Relative lamp tests were used to monitor the stability of the instruments. Each site NILU-UV was scaled channel by channel to the traveling reference by performing solar comparisons. The method of scaling each channel separately was found to be successful, even though the differences between the raw data of the site NILU-UV and the reference instruments were, before the data correction, as much as 40%. After the correction, the mean ratios of erythemally weighted UV dose rates measured during the solar comparisons in 2000-2003 between the reference NILU-UV and the site NILU-UV were 1.007 +/- 0.011 and 1.012 +/- 0.012 for Ushuaia and Marambio, respectively, when the solar zenith angle varied up to 80°. These results make possible the scientific use of NILU-UV data measured simultaneously at quite different

  18. A Maturing Tephra Record in the West Antarctic Ice Sheet

    Science.gov (United States)

    Dunbar, N. W.; Kurbatov, A.; McIntosh, W. C.

    2011-12-01

    Tephra layers found in many Antarctic ice cores range from sub-centimeter thick, visible layers to cryptotephra consisting of sparse, fine-grained (Takahe, tephra from which have also been recognized in the marine record (Hillenbrand et al., 1988). A well-defined ash layer is found at a depth of between 190.37-190.39 m depth in the WAIS Divide core, containing 20 um ash shards that are chemically correlated to the the Pleaides volcanoes, in northern Victoria Land. This tephra layer correlates to one found in a Siple Dome (B) ice core (97.2 to 97.7 m depth) and in the Taylor Dome ice core (79.2 m depth). Deeper parts of the WAIS Divide ice core correspond to a time interval of abundant regional volcanism, represented by the large number of visible dust bands and cloudy layers in the core (A. Orsi, pers. comm., 2010). A distinct "visible brown layer" at a depth of 1586.363 m. (8.279 Ky BP preliminary age) is very likely to be from a major eruption of the West Antarctic volcano Mt. Takahe (8.2±5.4 , Wilch et al., 1999). This layer is found at a depth of 503.58-503.87 m in the Siple Dome A core (SMDA) corresponding to 8.167-8.181 Ky before 1950, and almost certainly to a visible layer identified and analyzed in the Byrd ice core at 788 m (Palais et al., 1988). A visible double layer at 1741.246 m (9.57 KyBP preliminary age) may correspond to a very distinct tephra layer in the SDMA core at a depth of around 550 m (corresponding to an age of around 9.7 Ky before 1950). This layer is derived from the West Antarctic stratovolcano, Mt. Berlin. In the segment of WAIS Divide ice core between 2251 and 2557 m depth (15.2 to 20.6 preliminary age), numerous dust bands and cloudy layers are reported in the ice. This corresponds to the age of ice in the Byrd Core that contained many volcanic layers (Gow and Williamson, 1971), and also an interval in the SDMA where numerous distinct tephra layers associated with highly explosive eruptions of Mt. Berlin were found. Detailed

  19. Geoethical Approach to Antarctic Subglacial Lakes Exploration

    Science.gov (United States)

    Talalay, Pavel; Markov, Alexey; Sysoev, Mikhail

    2014-05-01

    Antarctic subglacial aquatic environment have become of great interest to the science community because they may provide unique information about microbial evolution, the past climate of the Earth, and the formation of the Antarctic ice sheet. Nowadays it is generally recognized that a vast network of lakes, rivers, and streams exists thousands of meters beneath Antarctic Ice Sheets. Up to date only four boreholes accessed subglacial aquatic system but three of them were filled with high-toxic drilling fluid, and the subglacial water was contaminated. Two recent exploration programs proposed by UK and USA science communities anticipated direct access down to the lakes Ellsworth and Whillans, respectively, in the 2012/2013 Antarctic season. A team of British scientists and engineers engaged in the first attempt to drill into Lake Ellsworth but failed. US research team has successfully drilled through 800 m of Antarctic ice to reach a subglacial lake Whillans and retrieve water and sediment samples. Both activities used hot-water drilling technology to access lakes. Hot water is considered by the world science community as the most clean drilling fluid medium from the present point of view but it cannot solve environmental problems in total because hot-water even when heated to 90 °C, filtered to 0.2 μm, and UV treated at the surface could pick up microorganisms from near-surface snow and circulate them in great volume through the borehole. Another negative impact of hot-water circulation medium is thermal pollution of subglacial water. The new approach to Antarctic subglacial lakes exploration is presented by sampling technology with recoverable autonomous sonde which is equipped by two hot-points with heating elements located on the bottom and top sides of the sonde. All down-hole sonde components will be sterilized by combination of chemical wash, HPV and UV sterilization prior using. At the beginning of the summer season sonde is installed on the surface of the

  20. The transition from diffuse to focused extension: Modeled evolution of the West Antarctic Rift system

    Science.gov (United States)

    Huerta, Audrey D.; Harry, Dennis L.

    2007-03-01

    Two distinct stages of extension are recognized in the West Antarctic Rift system (WARS). During the first stage, beginning in the Late Cretaceous, extension was broadly distributed throughout much of West Antarctica. A second stage of extension in the late Paleogene was focused primarily in the Victoria Land Basin, near the boundary with the East Antarctic craton. The transition to focused extension was roughly coeval with volcanic activity and strike-slip faulting in the adjacent Transantarctic Mountains. This spatial and temporal correspondence suggests that the transition in extensional style could be the result of a change in plate motions or impingement of a plume. Here we use finite element models to study the processes and conditions responsible for the two-stage evolution of rifting in the WARS. Model results indicate that the transition from a prolonged period of broadly distributed extension to a later period of focused rifting did not require a change in the regional stress regime (changes in plate motion), or deep mantle thermal state (impingement of a plume). Instead, we attribute the transition from diffuse to focused extension to an early stage dominated by the initially weak accreted lithosphere of West Antarctica, and a later stage that concentrated around a secondary weakness located at the boundary between the juvenile West Antarctica lithosphere and Precambrian East Antarctic craton. The modeled transition in extension from the initially weak West Antarctica region to the secondary weakness at the West Antarctic-East Antarctic boundary is precipitated by strengthening of the West Antarctica lithosphere during syn-extensional thinning and cooling. The modeled syn-extensional strengthening of the WARS lithosphere promotes a wide-rift mode of extension between 105 and ˜ 65 Ma. By ˜ 65 Ma most of the extending WARS region becomes stronger than the area immediately adjacent to the East Antarctic craton and extension becomes concentrated near the

  1. Antarctic Tephrochronology: A Maturing Record of Visible Layers and Cryptotephra

    Science.gov (United States)

    Dunbar, N. W.; Kurbatov, A.; McIntosh, W. C.

    2012-12-01

    Visible tephra layers, which represent important time-stratigraphic markers in ice-bound climate records, have been found in majority of the deep Antarctic ice cores. Ice core tephra layers range from sub-centimeter thick, visible layers to cryptotephra consisting of sparse, fine-grained (Takahe, tephra from which have also been recognized in the marine record (Hillenbrand et al., 1988). However, a well-defined ash layer recognized at a depth of between 190.37-190.39 m depth in the WDC06A core and several other ice cores, which contains 20 μm ash shards, was chemically characterized as being derived from the East Antarctic Pleiades volcanic center. Several tephra layers, including one that correlates between the SDMA and WDC06A cores, are thought to be related to South American volcanism. In terms of the West Antarctic regional tephra framework, a very distinct "visible brown layer", with glass shards up to 20 μm in diameter, found at a depth of 1586.363 m in WDC06A (8.279 ka B.P. preliminary age), chemically correlates to a major 40Ar/39Ar-dated (8.2±5.4) eruption of the West Antarctic volcano Mt. Takahe. This layer is also observed at a depth of between 503.58 and 503.87 m in the SMDA core, corresponding to ages between 8.167 and 8.181 ka B.P. (Dunbar and Kurbatov, 2011). A layer almost certainly corresponding to this one was also identified and analyzed in the Byrd ice core at a depth of 788 m (Palais et al., 1988). A tephra layer at a depth of 2441.95 m in WDC06A chemically correlates to a layer in SDMA at a depth of 707.00 m. This layer correlates to an eruption of Mt. Berlin which has been dated using 40Ar/39Ar at 18.2±5.8 ka B.P. Several other tephra layers from Mt. Berlin have been identified in the WDC06A and SDMA ice cores. Finally, a tephra layer with a grain size of between 100 and 200 microns, very coarse by ice core standards, has been identified at a depth of 2569.205 m depth in the WDC06A core. The grain size, morphology and composition of this

  2. Spring–summer albedo variations of Antarctic sea ice from 1982 to 2009

    International Nuclear Information System (INIS)

    This study examined the spring–summer (November, December, January and February) albedo averages and trends using a dataset consisting of 28 years of homogenized satellite data for the entire Antarctic sea ice region and for five longitudinal sectors around Antarctica: the Weddell Sea (WS), the Indian Ocean sector (IO), the Pacific Ocean sector (PO), the Ross Sea (RS) and the Bellingshausen–Amundsen Sea (BS). Time series data of the sea ice concentrations and sea surface temperatures were used to analyse their relations to the albedo. The results indicated that the sea ice albedo increased slightly during the study period, at a rate of 0.314% per decade, over the Antarctic sea ice region. The sea ice albedos in the PO, the IO and the WS increased at rates of 2.599% per decade (confidence level 99.86%), 0.824% per decade and 0.413% per decade, respectively, and the steepest increase occurred in the PO. However, the sea ice albedo in the BS decreased at a rate of −1.617% per decade (confidence level 95.05%) and was near zero in the RS. The spring–summer average albedo over the Antarctic sea ice region was 50.24%. The highest albedo values were mainly found on the continental coast and in the WS; in contrast, the lowest albedo values were found on the outer edge of the sea ice, the RS and the Amery Ice Shelf. The average albedo in the western Antarctic sea ice region was distinctly higher than that in the east. The albedo was significantly positively correlated with sea ice concentration (SIC) and was significantly negatively correlated with sea surface temperature (SST); these scenarios held true for all five longitudinal sectors. Spatially, the higher surface albedos follow the higher SICs and lower SST patterns. The increasing albedo means that Antarctic sea ice region reflects more solar radiation and absorbs less, leading to a decrease in temperature and much snowfall on sea ice, and further resulted in an increase in albedo. Conversely, the decreasing

  3. Response of the Antarctic Stratosphere to Two Types of El Nino Events

    Science.gov (United States)

    Hurwitz, M. M.; Newman, P. A.; Oman, L. D.; Molod, A. M.

    2010-01-01

    This study is the first to identify a robust El Nino/Southern Oscillation (ENSO) signal in the Antarctic stratosphere. El Nino events are classified as either conventional "cold tongue" events (positive SST anomalies in the Nino 3 region) or "warm pool" events (positive SST anomalies in the Nino 4 region). The ERA-40, NCEP and MERRA meteorological reanalyses are used to show that the Southern Hemisphere stratosphere responds differently to these two types of El Nino events. Consistent with previous studies, "cold tongue" events do not impact temperatures in the Antarctic stratosphere. During "warm pool" El Nino events, the poleward extension and increased strength of the South Pacific Convergence Zone (SPCZ) favor an enhancement of planetary wave activity during the SON season. On average, these conditions lead to higher polar stratospheric temperatures and a weakening of the Antarctic polar jet in November and December, as compared with neutral ENSO years. The phase of the quasi-biennial oscillation (QBO) modulates the stratospheric response to "warm pool" El Nino events: the strongest planetary wave driving events are coincident with the easterly phase of the QBO.

  4. Temperature, lithosphere-asthenosphere boundary, and heat flux beneath the Antarctic Plate inferred from seismic velocities

    Science.gov (United States)

    An, Meijian; Wiens, Douglas A.; Zhao, Yue; Feng, Mei; Nyblade, Andrew; Kanao, Masaki; Li, Yuansheng; Maggi, Alessia; Lévêque, Jean-Jacques

    2015-12-01

    We estimate the upper mantle temperature of the Antarctic Plate based on the thermoelastic properties of mantle minerals and S velocities using a new 3-D shear velocity model, AN1-S. Crustal temperatures and surface heat fluxes are then calculated from the upper mantle temperature assuming steady state thermal conduction. The temperature at the top of the asthenosphere beneath the oceanic region and West Antarctica is higher than the dry mantle solidus, indicating the presence of melt. From the temperature values, we generate depth maps of the lithosphere-asthenosphere boundary and the Curie temperature isotherm. The maps show that East Antarctica has a thick lithosphere similar to that of other stable cratons, with the thickest lithosphere (~250 km) between Domes A and C. The thin crust and lithosphere beneath West Antarctica are similar to those of modern subduction-related rift systems in East Asia. A cold region beneath the Antarctic Peninsula is similar in spatial extent to that of a flat-subducted slab beneath the southern Andes, indicating a possible remnant of the Phoenix Plate, which was subducted prior to 10 Ma. The oceanic lithosphere generally thickens with increasing age, and the age-thickness correlation depends on the spreading rate of the ridge that formed the lithosphere. Significant flattening of the age-thickness curves is not observed for the mature oceanic lithosphere of the Antarctic Plate.

  5. Results of SPM sun photometer measurements at Mirny Antarctic station (58-60th RAE)

    Science.gov (United States)

    Kabanov, Dmitry M.; Prakhov, Aleksander N.; Radionov, Vladimir F.; Sakerin, Sergey M.

    2015-11-01

    The SPM portable sun photometer observations in the wavelength range of 0.34-2.14 μm are performed at Mirny Antarctic station since fall 2013. The data obtained are used to calculate the aerosol optical depth (AOD) and water vapor content of the atmosphere. The sun photometer intercalibration results and statistical characteristics of interdiurnal and seasonal variations in spectral AOD of the atmosphere are discussed. Estimates of interannual variations in the atmospheric AOD in the region of Mirny station and in the coastal zone of Antarctica are presented. The global background level of AOD of the Antarctic atmosphere is noted to be still about 0.02 at the wavelength of 0.5 μm.

  6. Spatial variation of ozone depletion rates in the springtime Antarctic polar vortex

    Science.gov (United States)

    Yung, Yuk L.; Allen, Mark; Crisp, David; Zurek, Richard W.; Sander, Stanley P.

    1990-01-01

    An area-mapping technique, designed to filter out synoptic perturbations of the Antarctic polar vortex such as distortion or displacement away from the pole, was applied to the Nimbus-7 TOMS (Total Ozone Mapping Spectrometer) data. This procedure reveals the detailed morphology of the temporal evolution of column O3. The results for the austral spring of 1987 suggest the existence of a relatively stable collar region enclosing an interior that is undergoing large variations. A simplified photochemical model of O3 loss and the temporal evolution of the area-mapped polar O3 are used to constrain the chlorine monoxide (ClO) concentrations in the springtime Antarctic vortex. The O3 loss rates could be larger than deduced here because of underestimates of total O3 by TOMS near the terminator.

  7. Reflectance of Antarctic surfaces from multispectral radiometers: The correction of atmospheric effects

    International Nuclear Information System (INIS)

    Monitoring reflectance of polar icecaps has relevance in climate studies. In fact, climate changes produce variations in the morphology of ice and snow covers, which are detectable as surface reflectance change. Surface reflectance can be retrieved from remotely sensed data. However, absolute values independent of atmospheric turbidity and surface altitude can only be obtained after removing masking effects of the atmosphere. An atmospheric correction model, accounting for surface and sensor altitudes above sea level, is described and validated through data detected over Antarctic surfaces with a Barnes Modular Multispectral Radiometer having bands overlapping those of the Landsat Thematic Mapper. The model is also applied in a sensitivity analysis to investigate error induced in reflectance obtained from satellite data by indeterminacy in optical parameters of atmospheric constituents. Results show that indeterminacy in the atmospheric water vapor optical thickness is the main source of nonaccuracy in the retrieval of surface reflectance from data remotely sensed over Antarctic regions

  8. 77 FR 5403 - Conservation of Antarctic Animals and Plants

    Science.gov (United States)

    2012-02-03

    ... From the Federal Register Online via the Government Publishing Office NATIONAL SCIENCE FOUNDATION 45 CFR Part 670 Conservation of Antarctic Animals and Plants AGENCY: National Science Foundation. ACTION: Final rule. SUMMARY: Pursuant to the Antarctic Conservation Act of 1978, The National...

  9. Biological studies in the Antarctic waters: A review

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.

    stream_size 12 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_407.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_407.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO...

  10. Laboratory study of nitrate photolysis in Antarctic snow

    DEFF Research Database (Denmark)

    Berhanu, Tesfaye A.; Meusinger, Carl; Erbland, Joseph;

    2014-01-01

    Atmospheric nitrate is preserved in Antarctic snow firn and ice. However, at low snow accumulation sites, post-depositional processes induced by sunlight obscure its interpretation. The goal of these studies (see also Paper I by Meusinger et al. [" Laboratory study of nitrate photolysis in Antarc...... reproduce the stable isotopic composition of nitrate found in Antarctic snow profiles. © 2014 Author(s)....

  11. An evaluation of selected Neidium species from the Antarctic Region

    Czech Academy of Sciences Publication Activity Database

    Hamilton, P. B.; De Haan, M.; Kopalová, Kateřina; Zidarova, R.; Van de Vijver, B.

    2014-01-01

    Roč. 29, č. 1 (2014), s. 27-40. ISSN 0269-249X R&D Projects: GA MŠk ME 934; GA MŠk ME 945 Institutional support: RVO:67985939 Keywords : Bacillariophyta * biogeography * Neidium Subject RIV: EF - Botanics Impact factor: 1.746, year: 2014

  12. Fast recession of a West Antarctic glacier

    OpenAIRE

    Rignot, EJ

    1998-01-01

    Satellite radar interferometry observations of Pine Island Glacier, West Antarctica, reveal that the glacier hinge-line position retreated 1.2 ± 0.3 kilometers per year between 1992 and 1996, which in turn implies that the ice thinned by 3.5 ± 0.9 meters per year. The fast recession of Pine Island Glacier, predicted to be a possible trigger for the disintegration of the West Antarctic Ice Sheet, is attributed to enhanced basal melting of the glacier floating tongue by warm ocean waters.

  13. Automatic focusing system of BSST in Antarctic

    Science.gov (United States)

    Tang, Peng-Yi; Liu, Jia-Jing; Zhang, Guang-yu; Wang, Jian

    2015-10-01

    Automatic focusing (AF) technology plays an important role in modern astronomical telescopes. Based on the focusing requirement of BSST (Bright Star Survey Telescope) in Antarctic, an AF system is set up. In this design, functions in OpenCV is used to find stars, the algorithm of area, HFD or FWHM are used to degree the focus metric by choosing. Curve fitting method is used to find focus position as the method of camera moving. All these design are suitable for unattended small telescope.

  14. Longitudinal surface structures (flowstripes on Antarctic glaciers

    Directory of Open Access Journals (Sweden)

    N. F. Glasser

    2011-11-01

    Full Text Available Longitudinal surface structures (''flowstripes'' are common on many glaciers but their origin and significance are poorly understood. In this paper we present observations of the development of these longitudinal structures from four different Antarctic glacier systems (the Lambert Glacier/Amery Ice Shelf area, outlet glaciers in the Ross Sea sector, ice-shelf tributary glaciers on the Antarctic Peninsula, and the onset zone of a tributary to the Recovery Glacier Ice Stream in the Filchner Ice Shelf area. Mapping from optical satellite images demonstrates that longitudinal surface structures develop in two main situations: (1 as relatively wide flow stripes within glacier flow units and (2 as relatively narrow flow stripes where there is convergent flow around nunataks or at glacier confluence zones. Our observations indicate that the confluence features are narrower, sharper, and more clearly defined features. They are characterised by linear troughs or depressions on the ice surface and are much more common than the former type. Longitudinal surface structures within glacier flow units have previously been explained as the surface expression of localised bed perturbations but a universal explanation for those forming at glacier confluences is lacking. Here we propose that these features are formed at zones of ice acceleration and extensional flow at glacier confluences. We provide a schematic model for the development of longitudinal surface structures based on extensional flow that can explain their ridge and trough morphology as well as their down-ice persistence.

  15. Interhemispheric coupling and warm Antarctic interglacials

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    P. B. Holden

    2009-12-01

    Full Text Available Ice core evidence indicates that even though atmospheric CO2 concentrations did not exceed ~300 ppm at any point during the last 800 000 years, East Antarctica was at least ~3–4 °C warmer than pre-industrial (CO2 ~280 ppm in each of the last four interglacials. During the previous three interglacials, this anomalous warming was short lived (~3 000 years and apparently occurred before the completion of Northern Hemisphere deglaciation. Hereafter, we refer to these periods as "Warmer than Present Transients" (WPTs. We here present transient 800 kyr simulations using the intermediate complexity model GENIE-1 which suggest that WPTs could be explained as a consequence of the meltwater-forced slowdown of the Atlantic Meridional Overturning Circulation (AMOC during glacial terminations. It is well known that a slowed AMOC would increase southern Sea Surface Temperature (SST through the bipolar seesaw. Observational data supports this hypothesis, suggesting that the AMOC remained weak throughout the terminations preceding WPTs, strengthening rapidly at a time which coincides closely with peak Antarctic temperature. In order to investigate model and boundary condition uncertainty, we additionally present three ensembles of transient GENIE-1 simulations across Termination II (135 000 to 124 000 BP and three snapshot HadCM3 simulations at 130 000 Before Present (BP. These simulations together reproduce both the timing and magnitude of WPTs, and point to the potential importance of an albedo feedback associated with West Antarctic Ice Sheet (WAIS retreat.

  16. Solar power for an Antarctic rover

    Science.gov (United States)

    Lever, J. H.; Ray, L. R.; Streeter, A.; Price, A.

    2006-03-01

    Sensors mounted on mobile robots could serve a variety of science missions in Antarctica. Although weather conditions can be harsh, Antarctic snowfields offer unique conditions to facilitate long-distance robot deployment: the absence of obstacles, firm snow with high albedo, and 24 h sunlight during the summer. We have developed a four-wheel-drive, solar-powered rover that capitalizes on these advantages. Analyses and field measurements confirm that solar power reflected from Antarctic snow contributes 30-40% of the power available to a robot consisting of a five-side box of solar panels. Mobility analyses indicate that the 80 kg rover can move at 0.8 m s-1 during clear sky conditions on firm snow into a 5 m s-1 headwind, twice the speed needed to achieve the design target of 500 km in 2 weeks. Local winter tests of the chassis demonstrated good grade-climbing ability and lower than predicted rolling resistance. Tests of the completed robot occurred in Greenland in 2005.

  17. Mitochondrial sequence divergence among Antarctic killer whale ecotypes is consistent with multiple species.

    Science.gov (United States)

    LeDuc, Richard G; Robertson, Kelly M; Pitman, Robert L

    2008-08-23

    Recently, three visually distinct forms of killer whales (Orcinus orca) were described from Antarctic waters and designated as types A, B and C. Based on consistent differences in prey selection and habitat preferences, morphological divergence and apparent lack of interbreeding among these broadly sympatric forms, it was suggested that they may represent separate species. To evaluate this hypothesis, we compared complete sequences of the mitochondrial control region from 81 Antarctic killer whale samples, including 9 type A, 18 type B, 47 type C and 7 type-undetermined individuals. We found three fixed differences that separated type A from B and C, and a single fixed difference that separated type C from A and B. These results are consistent with reproductive isolation among the different forms, although caution is needed in drawing further conclusions. Despite dramatic differences in morphology and ecology, the relatively low levels of sequence divergence in Antarctic killer whales indicate that these evolutionary changes occurred relatively rapidly and recently. PMID:18524738

  18. Antarctic lakes (above and beneath the ice sheet): Analogues for Mars

    Science.gov (United States)

    Rice, J. W., Jr.

    The perennial ice covered lakes of the Antarctic are considered to be excellent analogues to lakes that once existed on Mars. Field studies of ice covered lakes, paleolakes, and polar beaches were conducted in the Bunger Hills Oasis, Eastern Antarctica. These studies are extended to the Dry Valleys, Western Antarctica, and the Arctic. Important distinctions were made between ice covered and non-ice covered bodies of water in terms of the geomorphic signatures produced. The most notable landforms produced by ice covered lakes are ice shoved ridges. These features form discrete segmented ramparts of boulders and sediments pushed up along the shores of lakes and/or seas. Sub-ice lakes have been discovered under the Antarctic ice sheet using radio echo sounding. These lakes occur in regions of low surface slope, low surface accumulations, and low ice velocity, and occupy bedrock hollows. The presence of sub-ice lakes below the Martian polar caps is possible. The discovery of the Antarctic sub-ice lakes raises possibilities concerning Martian lakes and exobiology.

  19. Site-Specific Variability in the Chemical Diversity of the Antarctic Red Alga Plocamium cartilagineum

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    Ryan M. Young

    2013-06-01

    Full Text Available Plocamium cartilagineum is a common red alga on the benthos of Antarctica and can be a dominant understory species along the western Antarctic Peninsula. Algae from this region have been studied chemically, and like “P. cartilagineum” from other worldwide locations where it is common, it is rich in halogenated monoterpenes, some of which have been implicated as feeding deterrents toward sympatric algal predators. Secondary metabolites are highly variable in this alga, both qualitatively and quantitatively, leading us to probe individual plants to track the possible link of variability to genetic or other factors. Using cox1 and rbcL gene sequencing, we find that the Antarctic alga divides into two closely related phylogroups, but not species, each of which is further divided into one of five chemogroups. The chemogroups themselves, defined on the basis of Bray-Curtis similarity profiling of GC/QqQ chromatographic analyses, are largely site specific within a 10 km2 area. Thus, on the limited geographical range of this analysis, P. cartilagineum displays only modest genetic radiation, but its secondary metabolome was found to have experienced more extensive radiation. Such metabogenomic divergence demonstrated on the larger geographical scale of the Antarctic Peninsula, or perhaps even continent-wide, may contribute to the discovery of cryptic speciation.

  20. Isolation and cellular fatty acid composition of psychrotrophic Halomonas strains from Antarctic sea water

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    Vipra Vijay Jadhav

    2013-06-01

    Full Text Available Microorganisms from extreme environments such as Arctic, Antarctic and Polar regions modulate their membrane fatty acids to survive in such habitats. Characterization of such microorganisms helps in understanding their physiological behavior. In view of this, the present article describes isolation, characterization and cellular fatty acid composition of three bacterial isolates from Antarctic sea water samples. All the three isolates (BRI 6, 29 and 31 were psychrotrophic Gram negative rods. Their 16S rRNA sequencing (around 1200 bp revealed that all three of them belong to genus Halomonas. Each of them showed 99% sequence similarity to Halomonas neptunia Eplume1 (NR 027218, H. boliviensis LC1 (NR 029080 and H. variabilis DSM 3051 (NR 042068. The fatty acid analysis of our isolates indicated i predominance of C 18:1, C 16:0 and C16:1 fatty acids and absence of trans fatty acids in all of them and ii higher percentage of anteiso fatty acids than of iso fatty acids in BRI 6. These characteristic features may contribute to their adaptation to the Antarctic habitat.

  1. Projected asymmetric response of Adélie penguins to Antarctic climate change

    Science.gov (United States)

    Cimino, Megan A.; Lynch, Heather J.; Saba, Vincent S.; Oliver, Matthew J.

    2016-01-01

    The contribution of climate change to shifts in a species’ geographic distribution is a critical and often unresolved ecological question. Climate change in Antarctica is asymmetric, with cooling in parts of the continent and warming along the West Antarctic Peninsula (WAP). The Adélie penguin (Pygoscelis adeliae) is a circumpolar meso-predator exposed to the full range of Antarctic climate and is undergoing dramatic population shifts coincident with climate change. We used true presence-absence data on Adélie penguin breeding colonies to estimate past and future changes in habitat suitability during the chick-rearing period based on historic satellite observations and future climate model projections. During the contemporary period, declining Adélie penguin populations experienced more years with warm sea surface temperature compared to populations that are increasing. Based on this relationship, we project that one-third of current Adélie penguin colonies, representing ~20% of their current population, may be in decline by 2060. However, climate model projections suggest refugia may exist in continental Antarctica beyond 2099, buffering species-wide declines. Climate change impacts on penguins in the Antarctic will likely be highly site specific based on regional climate trends, and a southward contraction in the range of Adélie penguins is likely over the next century. PMID:27352849

  2. Where is the West Antarctic Rift System in the Amundsen Sea and Bellingshausen Sea sectors?

    Science.gov (United States)

    Gohl, Karsten; Kalberg, Thomas; Eagles, Graeme; Dziadek, Ricarda; Kaul, Norbert; Spiegel, Cornelia; Lindow, Julia

    2015-04-01

    The West Antarctic Rift System (WARS) is one of the largest continental rifts globally, but its lateral extent, distribution of local rifts, timing of rifting phases, and mantle processes are still largely enigmatic. It has been presumed that the rift and its crustal extensional processes have widely controlled the history and development of West Antarctic glaciation with an ice sheet of which most is presently based at sub-marine level and which is, therefore, likely to be highly sensitive to ocean warming. While the western domain of the WARS in the Ross Sea has been studied in some detail, only recently have various geophysical and geochemical/thermochronological analyses revealed indications for its eastern extent in the Amundsen Sea and Bellingshausen Sea sectors of the South Pacific realm. The current model, based on these studies and additional data, suggests that the WARS activity included tectonic translateral, transtensional and extensional processes from the Amundsen Sea Embayment to the Bellingshausen Sea region of the southern Antarctic Peninsula. We present the range of existing hypotheses regarding the extent of the eastern WARS as well as published and yet unpublished data that support a conceptual WARS model for the eastern West Antarctica with implications for glacial onset and developments.

  3. Ancient climate change, antifreeze, and the evolutionary diversification of Antarctic fishes.

    Science.gov (United States)

    Near, Thomas J; Dornburg, Alex; Kuhn, Kristen L; Eastman, Joseph T; Pennington, Jillian N; Patarnello, Tomaso; Zane, Lorenzo; Fernández, Daniel A; Jones, Christopher D

    2012-02-28

    The Southern Ocean around Antarctica is among the most rapidly warming regions on Earth, but has experienced episodic climate change during the past 40 million years. It remains unclear how ancient periods of climate change have shaped Antarctic biodiversity. The origin of antifreeze glycoproteins (AFGPs) in Antarctic notothenioid fishes has become a classic example of how the evolution of a key innovation in response to climate change can drive adaptive radiation. By using a time-calibrated molecular phylogeny of notothenioids and reconstructed paleoclimate, we demonstrate that the origin of AFGP occurred between 42 and 22 Ma, which includes a period of global cooling approximately 35 Ma. However, the most species-rich lineages diversified and evolved significant ecological differences at least 10 million years after the origin of AFGPs, during a second cooling event in the Late Miocene (11.6-5.3 Ma). This pattern indicates that AFGP was not the sole trigger of the notothenioid adaptive radiation. Instead, the bulk of the species richness and ecological diversity originated during the Late Miocene and into the Early Pliocene, a time coincident with the origin of polar conditions and increased ice activity in the Southern Ocean. Our results challenge the current understanding of the evolution of Antarctic notothenioids suggesting that the ecological opportunity that underlies this adaptive radiation is not linked to a single trait, but rather to a combination of freeze avoidance offered by AFGPs and subsequent exploitation of new habitats and open niches created by increased glacial and ice sheet activity. PMID:22331888

  4. Deterrent activities in the crude lipophilic fractions of Antarctic benthic organisms: chemical defences against keystone predators

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    Laura Núñez-Pons

    2014-04-01

    Full Text Available Generalist predation constitutes a driving force for the evolution of chemical defences. In the Antarctic benthos, asteroids and omnivore amphipods are keystone opportunistic predators. Sessile organisms are therefore expected to develop defensive mechanisms mainly against such consumers. However, the different habits characterizing each predator may promote variable responses in prey. Feeding-deterrence experiments were performed with the circumpolar asteroid macropredator Odontaster validus to evaluate the presence of defences within the apolar lipophilic fraction of Antarctic invertebrates and macroalgae. A total of 51% of the extracts were repellent, yielding a proportion of 17 defended species out of the 31 assessed. These results are compared with a previous study in which the same fractions were offered to the abundant circum-Antarctic amphipod Cheirimedon femoratus. Overall, less deterrence was reported towards asteroids (51% than against amphipods (80.8%, principally in sponge and algal extracts. Generalist amphipods, which establish casual host–prey sedentary associations with biosubstrata (preferentially sponges and macroalgae, may exert more localized predation pressure than sea stars on certain sessile prey, which would partly explain these results. The nutritional quality of prey may interact with feeding deterrents, whose production is presumed to be metabolically expensive. Although optimal defence theory posits that chemical defences are managed and distributed as to guarantee protection at the lowest cost, we found that only a few organisms localized feeding deterrents towards most exposed and/or valuable body regions. Lipophilic defensive metabolites are broadly produced in Antarctic communities to deter opportunistic predators, although several species combine different defensive traits.

  5. Antarctic Forcing of Abrupt Global Climate Change During Isotope Stage 3

    Science.gov (United States)

    Turney, Christian; Jones, Richard; Phipps, Steven; Thomas, Zoë; Hogg, Alan; Kershaw, Peter; Fogwill, Christopher; Palmer, Jonathan; Bronk Ramsey, Christopher; Adolphi, Florian; Muscheler, Raimund; Hughen, Konrad; Staff, Richard; Grosvenor, Mark; Golledge, Nicholas; Haberle, Simon

    2016-04-01

    Contrasting Greenland and Antarctic temperature trends during the late Pleistocene (60,000 to 11,650 years ago) are thought to be driven by imbalances in the rate of formation of North Atlantic and Antarctic Deep Water (the 'bipolar seesaw'), with millennial-scale cooling Dansgaard-Oeschger (D-O) events in the north leading warming in the south. An alternative origin for these abrupt climate shifts, however, is the Southern Hemisphere whereby changes are transmitted globally via atmospheric and/or oceanic teleconnections. Testing these competing hypotheses is challenging given the relatively large uncertainties associated with dating terrestrial, marine and ice core chronologies. Here we use a fully coupled climate system model to investigate whether freshening of the Southern Ocean has extra-regional climate impacts. Focusing on an Isotope Stage 3 cooling event preserved in Antarctic ice cores immediately prior to Antarctic Isotope Maximum 4 (AIM 4; around 29,000 years ago) we undertook an ensemble of transient meltwater simulations. We observe no impact on the Atlantic Meridional Overturning Circulation (AMOC) from freshwater hosing in the Southern Ocean but a dramatic warming over the North Atlantic and contrasting precipitation patterns across the low latitudes. Exploiting a new bidecadally-resolved 14C calibration dataset obtained from New Zealand kauri (Agathis australis) we undertook intensive radiocarbon dating and high-resolution multiproxy analysis of the tropical Australia Lynch's Crater terrestrial peat sequence spanning this same period and find a synchronous change in hydroclimate to the purported meltwater event in the Southern Ocean. Our results imply Southern Ocean dynamics played a significant role in driving global climate change across this period via atmospheric teleconnections, with implications for other abrupt events through the late Pleistocene.

  6. Future Antarctic bed topography and its implications for ice sheet dynamics

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    S. Adhikari

    2014-01-01

    Full Text Available The Antarctic bedrock is evolving as the solid Earth responds to the past and ongoing evolution of the ice sheet. A~recently improved ice loading history suggests that the Antarctic Ice Sheet (AIS is generally losing its mass since the last glacial maximum (LGM. In a sustained warming climate, the AIS is predicted to retreat at a greater pace primarily via melting beneath the ice shelves. We employ the glacial isostatic adjustment (GIA capability of the Ice Sheet System Model (ISSM to combine these past and future ice loadings and provide the new solid Earth computations for the AIS. We find that the past loading is relatively less important than future loading on the evolution of the future bed topography. Our computations predict that the West Antarctic Ice Sheet (WAIS may uplift by a few meters and a few tens of meters at years 2100 and 2500 AD, respectively, and that the East Antarctic Ice Sheet (EAIS is likely to remain unchanged or subside minimally except around the Amery Ice Shelf. The Amundsen Sea Sector in particular is predicted to rise at the greatest rate; one hundred years of ice evolution in this region, for example, predicts that the coastline of Pine Island Bay approaches roughly 45 mm yr−1 in viscoelastic vertical motion. Of particular importance, we systematically demonstrate that the effect of a pervasive and large GIA uplift in the WAIS is associated with the flattening of reverse bed, reduction of local sea depth, and thus the extension of grounding line (GL towards the continental shelf. Using the 3-D higher-order ice flow capability of ISSM, such a migration of GL is shown to inhibit the ice flow. This negative feedback between the ice sheet and the solid Earth may promote the stability to marine portions of the ice sheet in future.

  7. Leaf and floral heating in cold climates: do sub-Antarctic megaherbs resemble tropical alpine giants?

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    Lorna Little

    2016-08-01

    Full Text Available High latitude and altitude floras are characterized by low-statured, small, wind-pollinated plants, which mainly reproduce by self-pollination or asexual reproduction. However, at odds with this are some sub-Antarctic islands that have plant species with giant growth forms and large, brightly coloured flowers which require insect visitation for pollination. The size, colour and shape of the inflorescences and leaves of these megaherbs suggest thermal benefits similar to giant tropical alpine plants of equatorial Africa, South America and Hawaii. We evaluated whether heating occurs in sub-Antarctic megaherbs, and to what extent it is related to environmental variables. We measured leaf and inflorescence temperature in six sub-Antarctic megaherb species on Campbell Island, latitude 52.3°S, New Zealand Biological Region. Using thermal imaging techniques, in combination with measurement of solar radiation, ambient air temperature, wind speed, wind chill and humidity, we assessed environmental influences on leaf and floral heating. We found that leaf and inflorescence temperatures of all megaherbs were higher than simultaneously measured ambient temperatures. Greatest heating was seen in Pleurophyllum speciosum, with observed leaves 9°C higher, and inflorescences nearly 11°C higher, than ambient temperature. Heating was highly correlated with brief, unpredictable periods of solar radiation, and occurred most rapidly in species with hairy, corrugated leaves and darkly pigmented, densely packed inflorescences. This is the first evidence that floral and leaf heating occurs in sub-Antarctic megaherbs, and suggests that leaf hairiness, flower colour and shape could provide thermal benefits like those seen in tropical alpine megaherbs.

  8. Evaluation of soil bioremediation techniques in an aged diesel spill at the Antarctic Peninsula.

    Science.gov (United States)

    de Jesus, Hugo E; Peixoto, Raquel S; Cury, Juliano C; van Elsas, Jan D; Rosado, Alexandre S

    2015-12-01

    Many areas on the Antarctic continent already suffer from the direct and indirect influences of human activities. The main cause of contamination is petroleum hydrocarbons because this compound is used as a source of energy at the many research stations around the continent. Thus, the current study aims to evaluate treatments for bioremediation (biostimulation, bioaugmentation, and bioaugmentation + biostimulation) using soils from around the Brazilian Antarctic Station "Comandante Ferraz" (EACF), King George Island, Antarctic Peninsula. The experiment lasted for 45 days, and at the end of this period, chemical and molecular analyses were performed. Those analyses included the quantification of carbon and nitrogen, denaturing gradient gel electrophoresis (DGGE) analysis (with gradient denaturation), real-time PCR, and quantification of total hydrocarbons and polyaromatics. Molecular tests evaluated changes in the profile and quantity of the rrs genes of archaea and bacteria and also the alkB gene. The influence of the treatments tested was directly related to the type of soil used. The work confirmed that despite the extreme conditions found in Antarctic soils, the bacterial strains degraded hydrocarbons and bioremediation treatments directly influenced the microbial communities present in these soils even in short periods. Although the majority of the previous studies demonstrate that the addition of fertilizer seems to be most effective at promoting bioremediation, our results show that for some conditions, autochthonous bioaugmentation (ABA) treatment is indicated. This work highlights the importance of understanding the processes of recovery of contaminated environments in polar regions because time is crucial to the soil recovery and to choosing the appropriate treatment. PMID:26286513

  9. The Australasian Antarctic Expedition 2013-2014: Practicing 'Citizen-Science' in a Changing World

    Science.gov (United States)

    Fogwill, C. J.; Turney, C. S.

    2014-12-01

    Government funding is the cornerstone of modern science. But with declining investment in science across most of the Western World, a major challenge for society is where best to place what little resource we have. Which research questions should have the greatest priority? Nowhere are these issues more pressing than in the Antarctic, where bases have and continue to play host to 'big-science', multi-year programmes of research, locking up logistical support and costs. But in a warming world, the areas with the greatest effects of climate change aren't always near government research stations. With this in mind, in 2012 a plan was formed to visit Commonwealth Bay, a remote area off the East Antarctic Ice Sheet, where in 2010, an iceberg the size of Rhode Island, known as B09B, dramatically knocked a 60-mile long tongue of ice off the Mertz Glacier into the Southern Ocean, setting off a cascade of change. Inspired by the expeditions of the past, we advertised berths for sale to take citizen scientists south with us, harnessing their interest, experience and investment. People responded far and wide. We were oversubscribed, and the Australasian Antarctic Expedition 2013-2014 was born. With the Russian-owned MV Akademik Shokalskiy as the expedition vessel, we set out south from the New Zealand port of Bluff in late November 2013. During our journey south and on the ice we undertook a number of scientific firsts for the region actively engaging the volunteer scientists on board in projects ranging from oceanography, biology, ecology, geology and glaciaology. The expedition demostrated how private funding could support targeted programmes of research and communicate it to the wider world. Small-science research can capture the public's imagination and also reap real scientific outputs. Although it is a funding model developed in the Antarctic a hundred years ago, the beauty is it can applied anywhere in the world.

  10. Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

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    T. O. Holt

    2013-05-01

    Full Text Available George VI Ice Shelf (GVIIS is located on the Antarctic Peninsula, a region where several ice shelves have undergone rapid breakup in response to atmospheric and oceanic warming. We use a combination of optical (Landsat, radar (ERS 1/2 SAR and laser altimetry (GLAS datasets to examine the response of GVIIS to environmental change and to offer an assessment on its future stability. The spatial and structural changes of GVIIS (ca. 1973 to ca. 2010 are mapped and surface velocities are calculated at different time periods (InSAR and optical feature tracking from 1989 to 2009 to document changes in the ice shelf's flow regime. Surface elevation changes are recorded between 2003 and 2008 using repeat track ICESat acquisitions. We note an increase in fracture extent and distribution at the south ice front, ice-shelf acceleration towards both the north and south ice fronts and spatially varied negative surface elevation change throughout, with greater variations observed towards the central and southern regions of the ice shelf. We propose that whilst GVIIS is in no imminent danger of collapse, it is vulnerable to ongoing atmospheric and oceanic warming and is more susceptible to breakup along its southern margin in ice preconditioned for further retreat.

  11. Antarctic sea ice variability and trends, 1979–2010

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    D. J. Cavalieri

    2012-03-01

    Full Text Available In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978–December 2010 reveal an overall positive trend in ice extents of 17 100 ± 2300 km2 yr−1. Much of the increase, at 13 700 ± 1500 km2 yr−1, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has, like the Arctic, instead experienced significant sea ice decreases, with an overall ice extent trend of −8200 ± 1200 km2 yr−1. When examined through the annual cycle over the 32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and Western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but differences in the magnitudes of the two trends identify regions with overall increasing ice concentrations and others with overall decreasing ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

  12. Presence of parasites in pinnipeds from the Antarctic Peninsula Presencia de parásitos en pinnípedos de la Península Antártica

    OpenAIRE

    Rengifo Herrera, María del Carmen

    2013-01-01

    NOTA 520 8 The Antarctic region is the most isolated on earth. Recently, it has been recognised as a place worthy of very high standards of environmental protection. However, the constant human intromission and the worldwide environmental degradation have been identified as serious risks in the introduction and spread of diseases, exerting an influence on health of Antarctic wildlife. With regard to this topic, marine mammals have been described as prime sentinels of aquatic ecosystems. Pin...

  13. Different adaptations of Chinese winter-over expeditioners during prolonged Antarctic and sub-Antarctic residence

    Science.gov (United States)

    Chen, Nan; Wu, Quan; Li, Hao; Zhang, Tao; Xu, Chengli

    2016-05-01

    Prolonged residence in Antarctica is characterized by exposure to isolated, confined, and extreme (ICE) environment. Winter-over expeditioners at research stations often exhibit a complex of psychophysiological symptoms, which varied by stations and sociocultural backgrounds. To understand the different patterns of psychophysiological responses provoked by environmental stress, we conducted a longitudinal assessment of mood and endocrine function in two groups of Chinese expeditioners who were deployed to sub-Antarctic (Great Wall Station, 62°S, N = 12) and Antarctic (Zhongshan Station, 66°S, N = 16) from December 2003 to 2005. Measures of mood, thyroid function, the levels of plasma catecholamine, and circulating interleukins were obtained at departure from China, mid-winter (Antarctica), end of winter (Antarctica), and return to China, respectively. The Zhongshan Station crew experienced significant increases in fatigue, anger, tension, confusion, and decrease in free thyroxine (FT4), norepinephrine (NE), and epinephrine (E) during the winter, increase in thyrotropin (TSH) and total triiodothyronine (TT3) when returning, whereas their counterparts at Great Wall Station only experienced increased TT3 after deployment. Moreover, compared with the Great Wall Station crew, the Zhongshan Station crew exhibited greater increase in anger, greater decrease in FT4, total thyroxine (TT4), NE and E over the winter, and greater increase in TSH when returning. Chinese expeditioners who lived and worked at the Antarctic station and the sub-Antarctic station for over a year showed different change patterns in mood and endocrine hormones. Negative mood and endocrine dysfunction were positively associated with the severity of environment. The study is a supplement to scientific knowledge on psychophysiological variation under ICE environment, which has certain applied value for the development of preventive countermeasures or interventions.

  14. Near UV atmospheric absorption measurements from the DC-8 aircraft during the 1987 airborne Antarctic ozone experiment

    Science.gov (United States)

    Wahner, A.; Jakoubek, R. O.; Ravishankara, A. R.; Mount, G. H.; Schmeltekopf, A. L.

    1988-01-01

    During the Airborne Antarctic Ozone Experiment from 28 August to 30 September 1987 near UV zenith scattered sky measurements were made over Antarctic from the NASA DC-8 aircraft using a one third m spectrograph equipped with a diode-array detector. Scattered sky light data in the wavelength range 348 nm to 388 nm was spectrally analyzed for O3, NO2, OClO, and BrO column abundances. Slant column abudances of O3, NO2, OClO and BrO were determined, using a computer algorithm of non-linear and linear least square correlation of Antarctic scattered sky spectra to laboratory absorption cross section data. Using measured vertical electrochemical sonde ozone profiles from Palmer, Halley Bay, and the South Pole Stations the slant columns of O3 were converted into vertical column abundances. The vertical column amounts of NO2, OClO, and BrO were derived using vertical profiles calculated by a chemical model appropriate for Antarctica. NO2 vertical column abundances show steep latitudinal decrease with increasing latitude for all 13 flights carried out during the mission. In the regions where NO2 abudances are low, OClO and BrO were observed. The spatial and temporal vertical column abundances of these species are discussed in the context of the chemistry and dynamics in the antarctic polar vortex during the austral spring.

  15. Contribution of liquid, NAT and ice particles to chlorine activation and ozone depletion during Antarctic winter and spring

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    O. Kirner

    2014-06-01

    Full Text Available Heterogeneous reactions in the Antarctic stratosphere are the cause of chlorine activation and ozone depletion, but the relative roles of different types of PSCs in chlorine activation is an open question. We use multi-year simulations of the chemistry-climate model EMAC to investigate the impact that the various types of PSCs have on Antarctic chlorine activation and ozone loss. One standard and three sensitivity EMAC simulations have been performed. The results of these simulations show that the significance of heterogeneous reactions on NAT and ice particles, in comparison to liquid particles, is subordinate regarding chlorine activation and ozone depletion in Antarctic winter and spring. The heterogeneous chemistry on liquid particles is sufficient to activate at least 90% of the chlorine reservoir species. With the exception of the upper PSC regions between 10 and 30 hPa where temporarily the ice particles have a relevant contribution to the chlorine activation and during the initial PSC occurrence with short NAT contributions the liquid particles alone are sufficient to activate almost all of the available chlorine. In the model simulations heterogeneous chemistry on liquid particles is responsible for more than 90% of the ozone depletion in Antarctic spring. Only up to 5 DU of column ozone in high southern latitudes is depleted by chlorine activation due to additional heterogeneous chemistry on ice particles and less than 0.5 DU due to additional heterogeneous chemistry on NAT particles.

  16. Biomarkers and Microbial Fossils In Antarctic Rocks

    Science.gov (United States)

    Wierzchos, J.; Ascaso, C.

    Lithobiontic microbial communities living within Antarctic rocks are an example of survival in an extremely cold and dry environment. Any unfavourable change in ex- ternal conditions can result in the death and disappearance of microscopic organisms, and this may be followed by the appearance of trace biomarkers and microbial fossils. The extinction of these microorganisms in some zones of the Ross Desert, probably provoked by the hostile environment, might be considered a good terrestrial analogue of the first stage of the disappearance of possible life on early Mars. Granite samples from maritime Antarctica (Granite Harbour) and sandstone rocks from the continental Ross Desert were collected with the aim of searching for biomarkers and microbial fossils at the microscopic level of observation. To this end, a novel in situ applica- tion of scanning electron microscopy with backscattered electron imaging was com- bined with the simultaneous use of X-ray energy dispersive spectroscopy techniques. Our findings confirm the existence of inorganic biomarkers in the form of physico- chemically bioweathered minerals within the granitic rocks. The presence of Fe-rich diagenetic minerals, such as iron hydroxide nanocrystals and biogenic clays around chasmoendolithic hyphae and bacterial cells was also observed. Others biomarkers, including inorganic deposits such as calcium oxalates and silica accumulations, are clear signs of endolithic microorganism activity. The interior of the sandstone rocks (Ross Desert, Mt. Fleming) reveal the presence of microbial fossils of algae and other endolithic microorganisms. These microbial fossils, detected for the first time within Antarctic rocks, contain well preserved and morphologically distinguishable relics of ultrastructural cytoplasm elements, such as cell walls, chloroplast membranes, and oc- casionally, pyrenoids and traces of organic matter. These structures are similar to those observed in live cells also found in Antarctic

  17. Antarctic sea ice variability and trends, 1979–2010

    Directory of Open Access Journals (Sweden)

    D. J. Cavalieri

    2012-08-01

    Full Text Available In sharp contrast to the decreasing sea ice coverage of the Arctic, in the Antarctic the sea ice cover has, on average, expanded since the late 1970s. More specifically, satellite passive-microwave data for the period November 1978–December 2010 reveal an overall positive trend in ice extents of 17 100 ± 2300 km2 yr−1. Much of the increase, at 13 700 ± 1500 km2 yr−1, has occurred in the region of the Ross Sea, with lesser contributions from the Weddell Sea and Indian Ocean. One region, that of the Bellingshausen/Amundsen Seas, has (like the Arctic instead experienced significant sea ice decreases, with an overall ice extent trend of −8200 ± 1200 km2 yr−1. When examined through the annual cycle over the 32-yr period 1979–2010, the Southern Hemisphere sea ice cover as a whole experienced positive ice extent trends in every month, ranging in magnitude from a low of 9100 ± 6300 km2 yr−1 in February to a high of 24 700 ± 10 000 km2 yr−1 in May. The Ross Sea and Indian Ocean also had positive trends in each month, while the Bellingshausen/Amundsen Seas had negative trends in each month, and the Weddell Sea and western Pacific Ocean had a mixture of positive and negative trends. Comparing ice-area results to ice-extent results, in each case the ice-area trend has the same sign as the ice-extent trend, but the magnitudes of the two trends differ, and in some cases these differences allow inferences about the corresponding changes in sea ice concentrations. The strong pattern of decreasing ice coverage in the Bellingshausen/Amundsen Seas region and increasing ice coverage in the Ross Sea region is suggestive of changes in atmospheric circulation. This is a key topic for future research.

  18. Aqueous uptake and sublethal toxicity of p,p′-DDE in non-feeding larval stages of Antarctic krill (Euphausia superba)

    International Nuclear Information System (INIS)

    This study evaluated the toxicological sensitivity of non-feeding larval stages of a key Antarctic species (Antarctic krill, Euphausia superba) to p,p′-dichlorodiphenyl dichloroethylene (p,p′-DDE) exposure. The aqueous uptake clearance rate of 84 mL g−1 preserved weight (p.w.) h−1 determined for p,p′-DDE in Antarctic krill larvae is comparable to previous findings for small cold water crustaceans and five times slower than the rates reported for an amphipod inhabiting warmer waters. Natural variations in larval physiology appear to influence contaminant uptake and larval krill behavioural responses, strongly highlighting the importance of time of measurement for ecotoxicological testing. Sublethal narcosis (immobility) was observed in larval Antarctic krill from p,p′-DDE body residues of 0.2 mmol/kg p.w., which is in agreement with findings for adult krill and temperate aquatic species. The finding of comparable body residue-based toxicity of p,p′-DDE between polar and temperate species supports the tissue residue approach for environmental risk assessment of polar ecosystems. - Highlights: ► p,p′-DDE uptake in Antarctic krill larvae compares with similar cold water species. ► However, uptake is slow compared to ‘warm water’ species. ► Larval physiology appears to affect behavioural responses to toxicant exposure. ► Larval Antarctic krill internal sensitivity to p,p′-DDE is similar to temperate species. ► Supporting the tissue residue approach for environmental risk assessment in polar regions. - For baseline toxicity, the body residue-based toxicological sensitivity of Antarctic krill larvae to p,p′-DDE exposure is comparable to that of temperate aquatic species.

  19. Changes in the West Antarctic ice sheet

    International Nuclear Information System (INIS)

    The portion of the West Antarctic ice sheet that flows into the Ross Sea is thinning in some places and thickening in others. These changes are not caused by any current climatic change, but by the combination of a delayed response to the end of the last global glacial cycle and an internal instability. The near-future impact of the ice sheet on global sea level is largely due to processes internal to the movement of the ice sheet, and not so much to the threat of a possible greenhouse warming. Thus the near-term future of the ice sheet is already determined. However, too little of the ice sheet has been surveyed to predict its overall future behavior

  20. Joint Antarctic School Expedition - An International Collaboration for High School Students and Teachers on Antarctic Science

    Science.gov (United States)

    Botella, J.; Warburton, J.; Bartholow, S.; Reed, L. F.

    2014-12-01

    The Joint Antarctic School Expedition (JASE) is an international collaboration program between high school students and teachers from the United States and Chile aimed at providing the skills required for establishing the scientific international collaborations that our globalized world demands, and to develop a new approach for science education. The National Antarctic Programs of Chile and the United States worked together on a pilot program that brought high school students and teachers from both countries to Punta Arenas, Chile, in February 2014. The goals of this project included strengthening the partnership between the two countries, and building relationships between future generations of scientists, while developing the students' awareness of global scientific issues and expanding their knowledge and interest in Antarctica and polar science. A big component of the project involved the sharing by students of the acquired knowledge and experiences with the general public. JASE is based on the successful Chilean Antarctic Science Fair developed by Chile´s Antarctic Research Institute. For 10 years, small groups of Chilean students, each mentored by a teacher, perform experimental or bibliographical Antarctic research. Winning teams are awarded an expedition to the Chilean research station on King George Island. In 2014, the Chileans invited US participation in this program in order to strengthen science ties for upcoming generations. On King George Island, students have hands-on experiences conducting experiments and learning about field research. While the total number of students directly involved in the program is relatively small, the sharing of the experience by students with the general public is a novel approach to science education. Research experiences for students, like JASE, are important as they influence new direction for students in science learning, science interest, and help increase science knowledge. We will share experiences with the

  1. Organic carbon in Antarctic snow: spatial trends and possible sources

    Digital Repository Service at National Institute of Oceanography (India)

    Antony, R.; Mahalinganathan, K.; Thamban, M.; Nair, S.

    Organic carbon records in Antarctic snow are sparse despite the fact that it is of great significance to global carbon dynamics, snow photochemistry, and air–snow exchange processes. Here, surface snow total organic carbon (TOC) along with sea...

  2. Climate Prediction Center (CPC) Daily Antarctic Oscillation Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Antarctic Oscillation (AAO) is a leading teleconnection pattern in the Southern Hemisphere circulation. It is calculated as the first Empirical Orthogonal...

  3. Morphogenesis of Antarctic Paleosols: Martian Analogue

    Science.gov (United States)

    Mahaney, W. C.; Dohm, J. M.; Baker, V. R.; Newsom, Horton E.; Malloch, D.; Hancock, R. G. V.; Campbell, Iain; Sheppard, D.; Milner, M. W.

    2001-11-01

    Samples of horizons in paleosols from the Quartermain Mountains of the Antarctic Dry Valleys (Aztec and New Mountain areas) were analyzed for their physical characteristics, mineralogy, chemical composition, and microbiology to determine the accumulation and movement of salts and other soluble constituents and the presence/absence of microbial populations. Salt concentrations are of special interest because they are considered to be a function of age, derived over time, in part from nearby oceanic and high-altitude atmospheric sources. The chemical composition of ancient Miocene-age paleosols in these areas is the direct result of the deposition and weathering of airborne-influxed salts and other materials, as well as the weathering of till derived principally from local dolerite and sandstone outcrops. Paleosols nearer the coast have greater contents of Cl, whereas near the inland ice sheet, nitrogen tends to increase on a relative basis. The accumulation and vertical distribution of salts and other soluble chemical elements indicate relative amounts of movement in the profile over long periods of time, in the order of several million years. Four of the six selected subsamples from paleosol horizons in two ancient soil profiles contained nil concentrations of bacteria and fungi. However, two horizons at depths of between 3 and 8 cm, in two profiles, yielded several colonies of the fungi Beauveria bassiana and Penicillium brevicompactum, indicating very minor input of organic carbon. Beauveria bassiana is often reported in association with insects and is used commercially for the biological control of some insect pests. Penicillium species are commonly isolated from Arctic, temperate, and tropical soils and are known to utilize a wide variety of organic carbon and nitrogen compounds. The cold, dry soils of the Antarctic bear a close resemblance to various present and past martian environments where similar weathering could occur and possible microbial populations

  4. Holocene subsurface temperature variability in the eastern Antarctic continental margin

    OpenAIRE

    Kim, J. H.; X. Crosta; Willmott, V.; Renssen, H.; J. Bonnin; Helmke, P.; Schouten, S.; Sinninghe Damsté, J.S.

    2012-01-01

    We reconstructed subsurface (similar to 45-200 m water depth) temperature variability in the eastern Antarctic continental margin during the late Holocene, using an archaeal lipid-based temperature proxy (TEX86 L). Our results reveal that subsurface temperature changes were probably positively coupled to the variability of warmer, nutrient-rich Modified Circumpolar Deep Water (MCDW, deep water of the Antarctic circumpolar current) intrusion onto the continental shelf. The TEX86 L record, in c...

  5. Wind profile radar for study of Antarctic air circulation

    International Nuclear Information System (INIS)

    After a brief discussion of meteorological methods used in the Antarctic, the paper gives an outline of a coordinated international research project whose objective is to set up a wind profiler radar station that would give meteorologists information regarding Antarctic atmospheric dynamics useful in their investigation of the causes and effects of the hole in the ozone layer. The radar instrumentation is to provide continuous readings of wind velocity at varying altitudes above the polar continent

  6. Obliquity-paced Pliocene West Antarctic ice sheet oscillations

    OpenAIRE

    Naish, T.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; Powell, R.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA.; Levy, R.; ANDRILL Science Management Office, University of Nebraska-Lincoln, Lincoln, USA; Wilson, G.; University of Otago, Department of Geology, PO Box 56, Leith Street, Dunedin, Otago 9001, New Zealand; Scherer, R.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA.; Talarico, F.; Universita` di Siena, Dipartimento di Scienze delle Terra, Via Laterina 8, I-53100 Siena, Italy; Krissek, L.; Ohio State University, Department of Geological Sciences, 275 Mendenhall Lab, 125 South Oval Mall, Columbus, Ohio 43210, USA; Niessen, F.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany; Pompilio, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Wilson, T.; Ohio State University, Department of Geological Sciences, 275 Mendenhall Lab, 125 South Oval Mall, Columbus, Ohio 43210, USA; Carter, L.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; DeConto, R.; Department of Geosciences, 233 Morrell Science Centre, University of Massachusetts, Amherst, Massachusetts 01003-9297, USA; Huybers, P.; Department of Earth and Planetary Sciences, Harvard University, Massachusetts 02138, USA; McKay, R.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington - New Zealand; Pollard, D.; Earth and Environmental Systems Institute, 2217 Earth-Engineering Science Bldg, University Park, PA 16802, USA

    2009-01-01

    Thirty years after oxygen isotope records frommicrofossils deposited in ocean sediments confirmed the hypothesis that variations in the Earth’s orbital geometry control the ice ages1, fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles2. Furthermore, an understanding of the behaviour of the marine-based West Antarctic ice sheet (WAIS) during the ‘warmer-than- present’ early-Pliocene epoch (̃5–3Myr ago) is needed to better constrain the possibl...

  7. Remotely-Sensed Glacier Change Estimation: a Case Study at Lindblad Cove, Antarctic Peninsula

    Science.gov (United States)

    Fieber, K. D.; Mills, J. P.; Miller, P. E.; Fox, A. J.

    2016-06-01

    This study builds on existing literature of glacier change estimation in polar regions and is a continuation of efforts aimed at unlocking the information encapsulated in archival aerial photography of Antarctic Peninsula glaciers. Historical aerial imagery acquired in 1957 over three marine-terminating glaciers at Lindblad Cove on the West Coast of Trinity Peninsula is processed to extract digital elevation models (DEMs) which are subsequently compared to DEMs generated from present day (2014) WorldView-2 satellite stereo-imagery. The new WorldView-2 images offer unprecedented sub-metre resolution of the Antarctic Peninsula and are explored here to facilitate improved registration and higher accuracy analysis of glacier changes. Unlike many studies, which focus on glacier fronts or only restricted regions of glaciers, this paper presents a complete coverage of elevation changes across the glacier surfaces for two of the studied glaciers. The study utilises a robust least squares matching technique to ensure precise registration of the archival and modern DEMs, which is applied due to lack of existing ground control in this remote region. This case study reveals that, while many glaciers in polar regions are reported as experiencing significant mass loss, some glaciers are stable or even demonstrate mass gain. All three glaciers reported here demonstrated overall mean increases in surface elevation, indicative of positive mass balance ranging from 0.6 to 5.8 metre water equivalent between 1957 and 2014.

  8. Absence of 21st century warming on Antarctic Peninsula consistent with natural variability.

    Science.gov (United States)

    Turner, John; Lu, Hua; White, Ian; King, John C; Phillips, Tony; Hosking, J Scott; Bracegirdle, Thomas J; Marshall, Gareth J; Mulvaney, Robert; Deb, Pranab

    2016-07-21

    Since the 1950s, research stations on the Antarctic Peninsula have recorded some of the largest increases in near-surface air temperature in the Southern Hemisphere. This warming has contributed to the regional retreat of glaciers, disintegration of floating ice shelves and a 'greening' through the expansion in range of various flora. Several interlinked processes have been suggested as contributing to the warming, including stratospheric ozone depletion, local sea-ice loss, an increase in westerly winds, and changes in the strength and location of low-high-latitude atmospheric teleconnections. Here we use a stacked temperature record to show an absence of regional warming since the late 1990s. The annual mean temperature has decreased at a statistically significant rate, with the most rapid cooling during the Austral summer. Temperatures have decreased as a consequence of a greater frequency of cold, east-to-southeasterly winds, resulting from more cyclonic conditions in the northern Weddell Sea associated with a strengthening mid-latitude jet. These circulation changes have also increased the advection of sea ice towards the east coast of the peninsula, amplifying their effects. Our findings cover only 1% of the Antarctic continent and emphasize that decadal temperature changes in this region are not primarily associated with the drivers of global temperature change but, rather, reflect the extreme natural internal variability of the regional atmospheric circulation. PMID:27443743

  9. Transcriptomics and comparative analysis of three antarctic notothenioid fishes.

    Directory of Open Access Journals (Sweden)

    Seung Chul Shin

    Full Text Available For the past 10 to 13 million years, Antarctic notothenioid fish have undergone extraordinary periods of evolution and have adapted to a cold and highly oxygenated Antarctic marine environment. While these species are considered an attractive model with which to study physiology and evolutionary adaptation, they are poorly characterized at the molecular level, and sequence information is lacking. The transcriptomes of the Antarctic fishes Notothenia coriiceps, Chaenocephalus aceratus, and Pleuragramma antarcticum were obtained by 454 FLX Titanium sequencing of a normalized cDNA library. More than 1,900,000 reads were assembled in a total of 71,539 contigs. Overall, 40% of the contigs were annotated based on similarity to known protein or nucleotide sequences, and more than 50% of the predicted transcripts were validated as full-length or putative full-length cDNAs. These three Antarctic fishes shared 663 genes expressed in the brain and 1,557 genes expressed in the liver. In addition, these cold-adapted fish expressed more Ub-conjugated proteins compared to temperate fish; Ub-conjugated proteins are involved in maintaining proteins in their native state in the cold and thermally stable Antarctic environments. Our transcriptome analysis of Antarctic notothenioid fish provides an archive for future studies in molecular mechanisms of fundamental genetic questions, and can be used in evolution studies comparing other fish.

  10. Effect of Antarctic solar radiation on sewage bacteria viability

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, K.A. [National Environment Research Council, Cambridge (United Kingdom). British Antarctic Survey

    2005-06-01

    The majority of coastal Antarctic research stations discard untreated sewage waste into the near-shore marine environment. However, Antarctic solar conditions are unique, with ozone depletion increasing the proportion of potentially damaging ultraviolet-B (UV-B) radiation reaching the marine environment. This study assessed the influence of Antarctic solar radiation on the viability of Escherichia coli and sewage microorganisms at Rothera Research Station, Adelaide Island, Antarctic Peninsula. Cell viability decreased with increased exposure time and with exposure to shorter wavelengths of solar radiation. Cell survival also declined with decreasing cloud cover, solar zenith angle and ozone column depth. However, particulates in sewage increased the persistence of viable bacteria. Ultraviolet radiation doses over Rothera Point were highest during the austral summer. During this time, solar radiation may act to partially reduce the number of viable sewage-derived microorganisms in the surface seawater around Antarctic outfalls. Nevertheless, this effect is not reliable and every effort should be made to fully treat sewage before release into the Antarctic marine environment. (author)

  11. Modeling Antarctic Subglacial Lake Filling and Drainage Cycles

    Science.gov (United States)

    Dow, Christine F.; Werder, Mauro A.; Nowicki, Sophie; Walker, Ryan T.

    2016-01-01

    The growth and drainage of active subglacial lakes in Antarctica has previously been inferred from analysis of ice surface altimetry data. We use a subglacial hydrology model applied to a synthetic Antarctic ice stream to examine internal controls on the filling and drainage of subglacial lakes. Our model outputs suggest that the highly constricted subglacial environment of our idealized ice stream, combined with relatively high rates of water flow funneled from a large catchment, can combine to create a system exhibiting slow-moving pressure waves. Over a period of years, the accumulation of water in the ice stream onset region results in a buildup of pressure creating temporary channels, which then evacuate the excess water. This increased flux of water beneath the ice stream drives lake growth. As the water body builds up, it steepens the hydraulic gradient out of the overdeepened lake basin and allows greater flux. Eventually this flux is large enough to melt channels that cause the lake to drain. Lake drainage also depends on the internal hydrological development in the wider system and therefore does not directly correspond to a particular water volume or depth. This creates a highly temporally and spatially variable system, which is of interest for assessing the importance of subglacial lakes in ice stream hydrology and dynamics.

  12. Risk maps for Antarctic krill under projected Southern Ocean acidification

    Science.gov (United States)

    Kawaguchi, S.; Ishida, A.; King, R.; Raymond, B.; Waller, N.; Constable, A.; Nicol, S.; Wakita, M.; Ishimatsu, A.

    2013-09-01

    Marine ecosystems of the Southern Ocean are particularly vulnerable to ocean acidification. Antarctic krill (Euphausia superba; hereafter krill) is the key pelagic species of the region and its largest fishery resource. There is therefore concern about the combined effects of climate change, ocean acidification and an expanding fishery on krill and ultimately, their dependent predators--whales, seals and penguins. However, little is known about the sensitivity of krill to ocean acidification. Juvenile and adult krill are already exposed to variable seawater carbonate chemistry because they occupy a range of habitats and migrate both vertically and horizontally on a daily and seasonal basis. Moreover, krill eggs sink from the surface to hatch at 700-1,000m (ref. ), where the carbon dioxide partial pressure (pCO2) in sea water is already greater than it is in the atmosphere. Krill eggs sink passively and so cannot avoid these conditions. Here we describe the sensitivity of krill egg hatch rates to increased CO2, and present a circumpolar risk map of krill hatching success under projected pCO2 levels. We find that important krill habitats of the Weddell Sea and the Haakon VII Sea to the east are likely to become high-risk areas for krill recruitment within a century. Furthermore, unless CO2 emissions are mitigated, the Southern Ocean krill population could collapse by 2300 with dire consequences for the entire ecosystem.

  13. Parasites of the Antarctic toothfish (Dissostichus mawsoni Norman, 1937 (Perciformes, Nototheniidae in the Pacific sector of the Antarctic

    Directory of Open Access Journals (Sweden)

    Ilya I. Gordeev

    2016-06-01

    Full Text Available The Antarctic toothfish (Dissostichus mawsoni Norman, 1937 is one of the main target species of commercial fisheries in the Antarctic. It is an endemic and is found along the shelf of Antarctica, as well as on the slopes of seamounts, underwater elevations and islands in the sub-Antarctic. It feeds on a variety of fish and cephalopods and can be an intermediate/paratenic host of some helminthes, whose final hosts are whales, seals, large rays and sharks. This article presents new data on toothfish infection in the Pacific sector of the Antarctic. Specimens were examined during commercial longline fishing in the Ross Sea and the Amundsen Sea in January–February 2013. Fourteen species of parasites were found using standard parasitological methods and genetic analysis.

  14. Mutation and evolutionary rates in adelie penguins from the antarctic.

    Directory of Open Access Journals (Sweden)

    Craig D Millar

    Full Text Available Precise estimations of molecular rates are fundamental to our understanding of the processes of evolution. In principle, mutation and evolutionary rates for neutral regions of the same species are expected to be equal. However, a number of recent studies have shown that mutation rates estimated from pedigree material are much faster than evolutionary rates measured over longer time periods. To resolve this apparent contradiction, we have examined the hypervariable region (HVR I of the mitochondrial genome using families of Adélie penguins (Pygoscelis adeliae from the Antarctic. We sequenced 344 bps of the HVR I from penguins comprising 508 families with 915 chicks, together with both their parents. All of the 62 germline heteroplasmies that we detected in mothers were also detected in their offspring, consistent with maternal inheritance. These data give an estimated mutation rate (micro of 0.55 mutations/site/Myrs (HPD 95% confidence interval of 0.29-0.88 mutations/site/Myrs after accounting for the persistence of these heteroplasmies and the sensitivity of current detection methods. In comparison, the rate of evolution (k of the same HVR I region, determined using DNA sequences from 162 known age sub-fossil bones spanning a 37,000-year period, was 0.86 substitutions/site/Myrs (HPD 95% confidence interval of 0.53 and 1.17. Importantly, the latter rate is not statistically different from our estimate of the mutation rate. These results are in contrast to the view that molecular rates are time dependent.

  15. A meta-analysis of human disturbance impacts on Antarctic wildlife.

    Science.gov (United States)

    Coetzee, Bernard W T; Chown, Steven L

    2016-08-01

    Evidence-based assessments are increasingly recognized as the best-practice approach to determine appropriate conservation interventions, but such assessments of the impact of human disturbance on wildlife are rare. Human disturbance comprises anthropogenic activities that are typically non-lethal, but may cause short- and/or longer-term stress and fitness responses in wildlife. Expanding human activity in the Antarctic region is of particular concern because it increases the scope and potential for increased human disturbance to wildlife in a region that is often thought of as relatively untouched by anthropogenic influences. Here, we use a meta-analytical approach to synthesise research on human disturbance to wildlife over the last three decades in the Antarctic and sub-Antarctic region. We combine data from 62 studies across 21 species on the behavioural, physiological and population responses of wildlife to pedestrian, vehicle and research disturbances. The overall effect size indicated a small, albeit statistically significant negative effect of disturbance (-0.39; 95% CI: -0.60 to -0.18). Negative effects were found for both physiological and population responses, but no evidence was found for a significant impact on wildlife behavioural responses. Negative effects were found across pedestrian, vehicle and research disturbances. Significant and high among-study heterogeneity was found in both disturbance and response sub-groups. Among species, it remains unclear to what extent different forms of disturbance translate into negative population responses. Most current guidelines to limit wildlife disturbance impacts in Antarctica recommend that approaches be tailored to animal behavioural cues, but our work demonstrates that behavioural changes do not necessarily reflect more cryptic, and more deleterious impacts, such as changes in physiology. In consequence, we recommend that pedestrian approach guidelines in the Antarctic region be revisited. Due to the high

  16. Effect of nutrient enrichments on the bacterial assemblage of Antarctic soils contaminated by diesel or crude oil

    OpenAIRE

    Delille, Daniel; Pelletier, Emilien; Delille, Bruno; Coulon, Fréderic

    2003-01-01

    There is an urgent need to develop new technologies to address the problem of soil remediation in high-latitude regions. A field study was initiated in January 1997 in two contaminated soils in Terre Adélie (Antarctica) with the objective of determining the long-term effectiveness of two bioremediation agents on total and hydrocarbon-degrading microbial assemblages under severe Antarctic conditions. This study was conducted in two steps, from January to July 1997 and from February to November...

  17. Chemical limnology in coastal East Antarctic lakes: monitoring future climate change in centres of endemism and biodiversity

    OpenAIRE

    Verleyen, Elie; Hodgson, Dominic; Gibson, John; Imura, Satoshi; Kaup, Enn; Kudoh, Sakake; De Wever, Aaike; Hoshino, Tamotsu; McMinn, Andrew; Obbels, Dagmar; Roberts, Donna; Roberts, Stephen; Sabbe, Kobe; Souffreau, Caroline; Tavernier, Ines

    2012-01-01

    Polar lakes respond quickly to climate-induced environmental changes. We studied the chemical limnological variability in 127 lakes and ponds from eight ice-free regions along the East Antarctic coastline, and compared repeat specific conductance measurements from lakes in the Larsemann Hills and Skarvsnes covering the periods 1987–2009 and 1997–2008, respectively. Specific conductance, the concentration of the major ions, pH and the concentration of the major nutrients underlie t...

  18. Changes in biological parameters of balaenopterid whales in the Antarctic, with special referece to southern minke whale

    OpenAIRE

    Hidehiro, Kato

    1986-01-01

    Historical changes in biological parameters of the southern balaenopterid whales were comparatively examined by reviewing the reports and information as well as on the new analyses for the minke whale (Balaenoptera acutorostrata) in the Antarctic region during the 1920's and the 1982/83 season. Two types of density-dependent changes were identified; changes by catch intensity itself for the blue (B. musculus) and the fin (B. physalus) whales and changes by interspecific competition for the se...

  19. On-site and in situ remediation technologies applicable to petroleum hydrocarbon contaminated sites in the Antarctic and Arctic

    OpenAIRE

    Camenzuli, Danielle; Freidman, Benjamin L.

    2015-01-01

    Petroleum hydrocarbon contaminated sites, associated with the contemporary and legacy effects of human activities, remain a serious environmental problem in the Antarctic and Arctic. The management of contaminated sites in these regions is often confounded by the logistical, environmental, legislative and financial challenges associated with operating in polar environments. In response to the need for efficient and safe methods for managing contaminated sites, several technologies have been a...

  20. β-Diversity and Species Accumulation in Antarctic Coastal Benthos: Influence of Habitat, Distance and Productivity on Ecological Connectivity

    OpenAIRE

    Thrush, Simon F.; Hewitt, Judi E.; Cummings, Vonda J.; Norkko, Alf; Chiantore, Mariachiara

    2010-01-01

    High Antarctic coastal marine environments are comparatively pristine with strong environmental gradients, which make them important places to investigate biodiversity relationships. Defining how different environmental features contribute to shifts in β-diversity is especially important as these shifts reflect both spatio-temporal variations in species richness and the degree of ecological separation between local and regional species pools. We used complementary techniques (species accumula...

  1. Assessing fuel spill risks in polar waters: Temporal dynamics and behaviour of hydrocarbons from Antarctic diesel, marine gas oil and residual fuel oil.

    Science.gov (United States)

    Brown, Kathryn E; King, Catherine K; Kotzakoulakis, Konstantinos; George, Simon C; Harrison, Peter L

    2016-09-15

    As part of risk assessment of fuel oil spills in Antarctic and subantarctic waters, this study describes partitioning of hydrocarbons from three fuels (Special Antarctic Blend diesel, SAB; marine gas oil, MGO; and intermediate grade fuel oil, IFO 180) into seawater at 0 and 5°C and subsequent depletion over 7days. Initial total hydrocarbon content (THC) of water accommodated fraction (WAF) in seawater was highest for SAB. Rates of THC loss and proportions in equivalent carbon number fractions differed between fuels and over time. THC was most persistent in IFO 180 WAFs and most rapidly depleted in MGO WAF, with depletion for SAB WAF strongly affected by temperature. Concentration and composition remained proportionate in dilution series over time. This study significantly enhances our understanding of fuel behaviour in Antarctic and subantarctic waters, enabling improved predictions for estimates of sensitivities of marine organisms to toxic contaminants from fuels in the region. PMID:27389459

  2. The influence of cosmic rays on the size of the Antarctic Ozone Hole

    CERN Document Server

    Madrigal, M Alvarez; Velasco, V M

    2010-01-01

    The Antarctic region in which severe ozone depletion has taken place is known as the ozone hole. This region has two basic indicators: the area, where the ozone abundance is low (size), and the quantity of ozone mass deficit (depth). The energetic particles that penetrate deeply into the atmosphere and galactic cosmic rays (GCR) modify the ozone abundance in the stratosphere. With this research project, we are looking for evidence of a connection between variations in the cosmic ray flux and variations in the size of the ozone hole. In addition, we are looking for signs of the kind of processes that physically connect GCR fluxes with variations in the stratospheric ozone hole size (OHS) in the Antarctic region. With this goal in mind, we also analyze here the atmospheric temperature (AT) anomalies, which have often been linked with such variations. Using Morlet's wavelet spectral analysis to compute the coherence between two time series, we found that during the analyzed period (1982-2005), there existed a co...

  3. The signatures of large-scale patterns of atmospheric variability in Antarctic surface temperatures

    Science.gov (United States)

    Marshall, Gareth J.; Thompson, David W. J.

    2016-04-01

    We investigate the impact that the four principal large-scale patterns of Southern Hemisphere (SH) atmospheric circulation variability have on Antarctic surface air temperature (SAT): (1) the southern baroclinic annular mode (BAM), which is associated with variations in extratropical storm amplitude; (2) the Southern Annular Mode (SAM), associated with latitudinal shifts in the midlatitude jet; and (3) the two Pacific-South American patterns (PSA1 and PSA2), which are characterized by wave trains originating in the tropical Pacific that extend across the SH extratropics. A key aspect is the use of 35 years of daily observations and reanalysis data, which affords a sufficiently large sample size to assess the signatures of the circulation patterns in both the mean and variability of daily mean SAT anomalies. The BAM exerts the weakest influence on Antarctic SAT, albeit it is still important over select regions. Consistent with previous studies, the SAM is shown to influence SAT across most of the continent throughout the year. The PSA1 also affects SAT across almost all of Antarctica. Regionally, both PSA patterns can exert a greater impact on SAT than the SAM but also have a significantly weaker influence during summer, reflecting the seasonality of the SH response to El Niño-Southern Oscillation. The SAM and PSA patterns have distinct signatures in daily SAT variance that are physically consistent with their signatures in extratropical dynamic variability. The broad-scale climate linkages identified here provide benchmarks for interpreting the Antarctic climate response to future changes in tropical sea surface temperatures, ozone recovery, and greenhouse gas increases.

  4. Holocene accumulation and ice flow near the West Antarctic Ice Sheet Divide ice core site

    Science.gov (United States)

    Koutnik, Michelle R.; Fudge, T. J.; Conway, Howard; Waddington, Edwin D.; Neumann, Thomas A.; Cuffey, Kurt M.; Buizert, Christo; Taylor, Kendrick C.

    2016-05-01

    The West Antarctic Ice Sheet Divide Core (WDC) provided a high-resolution climate record from near the Ross-Amundsen Divide in Central West Antarctica. In addition, radar-detected internal layers in the vicinity of the WDC site have been dated directly from the ice core to provide spatial variations in the age structure of the region. Using these two data sets together, we first infer a high-resolution Holocene accumulation-rate history from 9.2 kyr of the ice-core timescale and then confirm that this climate history is consistent with internal layers upstream of the core site. Even though the WDC was drilled only 24 km from the modern ice divide, advection of ice from upstream must be taken into account. We evaluate histories of accumulation rate by using a flowband model to generate internal layers that we compare to observed layers. Results show that the centennially averaged accumulation rate was over 20% lower than modern at 9.2 kyr before present (B.P.), increased by 40% from 9.2 to 2.3 kyr B.P., and decreased by at least 10% over the past 2 kyr B.P. to the modern values; these Holocene accumulation-rate changes in Central West Antarctica are larger than changes inferred from East Antarctic ice-core records. Despite significant changes in accumulation rate, throughout the Holocene the regional accumulation pattern has likely remained similar to today, and the ice-divide position has likely remained on average within 5 km of its modern position. Continent-scale ice-sheet models used for reconstructions of West Antarctic ice volume should incorporate this accumulation history.

  5. Antarctic Single Frames = Frame Level Records of Antarctica Photos: 1946 - 2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Aerial photographs of Antarctica from the United States Antarctic Resource Center (USARC) and the British Antarctic Survey (BAS) are maintained in this collection....

  6. Spatial distribution of atmospheric aerosol optical depth over Atlantic Ocean along the route of Russian Antarctic expeditions

    Science.gov (United States)

    Kabanov, Dmitry M.; Radionov, Vladimir F.; Sakerin, Sergey M.; Smirnov, Alexander

    2015-11-01

    During recent decade, Microtops and SPM portable sun photometers are used to perform annual measurements of aerosol optical depth (AOD) and water vapor content of the atmosphere over Atlantic Ocean along the route of the Russian Antarctic expeditions (RAE). The data accumulation has made it possible to analyze the specific features of the spatial distribution of spectral AOD of the atmosphere along eastern RAE route and identify six basic regions (latitudinal zones). The statistical characteristics of AOD in the identified oceanic regions in winter and spring periods are discussed. The estimates of finely and coarsely dispersed AOD components in different regions, as well as the interannual atmospheric AOD variations, are presented.

  7. Holocene records of geomagnetic field behavior from a north-south transect along the western Antarctic Peninsula

    Science.gov (United States)

    Brachfeld, S. A.; Shah, D. P.; St-Onge, M.; St-Onge, G.

    2013-12-01

    (-77°) values for each site, with a temporal wavelength of approximately 1000 years. The Holocene intensity of the geomagnetic field in this region was highest during the last 3000 years, broadly similar to patterns observed in the Northern Hemisphere. The records will be stacked in order to generate a regional reference curve for the Antarctic Peninsula. Moreover, these sites have the potential to fill a spatial gap in the distribution of paleomagnetic records that are used in geomagnetic field models.

  8. Iodine monoxide in the Antarctic snowpack

    Directory of Open Access Journals (Sweden)

    U. Platt

    2009-11-01

    Full Text Available Recent ground-based and space borne observations suggest the presence of significant amounts of iodine monoxide in the boundary layer of Antarctica, which are expected to have an impact on the ozone budget and might contribute to the formation of new airborne particles. So far, the source of these iodine radicals has been unknown. This paper presents long-term measurements of iodine monoxide at the German Antarctic research station Neumayer, which indicate that the snowpack is the main source for iodine radicals. The measurements have been performed using multi-axis differential optical absorption spectroscopy (MAX-DOAS. Using a coupled atmosphere-snowpack radiative transfer model, the comparison of the signals observed from scattered skylight and from light reflected by the snowpack yields several ppb of iodine monoxide in the upper layers of the sunlit snowpack throughout the year. Snow pit samples from Neumayer Station contain up to 700 ng/l of total iodine, representing a sufficient reservoir for these extraordinarily high IO concentrations.

  9. Iodine monoxide in the Antarctic snowpack

    Directory of Open Access Journals (Sweden)

    U. Frieß

    2010-03-01

    Full Text Available Recent ground-based and space borne observations suggest the presence of significant amounts of iodine monoxide in the boundary layer of Antarctica, which are expected to have an impact on the ozone budget and might contribute to the formation of new airborne particles. So far, the source of these iodine radicals has been unknown. This paper presents long-term measurements of iodine monoxide at the German Antarctic research station Neumayer, which indicate that high IO concentrations in the order of 50 ppb are present in the snow interstitial air. The measurements have been performed using multi-axis differential optical absorption spectroscopy (MAX-DOAS. Using a coupled atmosphere – snowpack radiative transfer model, the comparison of the signals observed from scattered skylight and from light reflected by the snowpack yields several ppb of iodine monoxide in the upper layers of the sunlit snowpack throughout the year. Snow pit samples from Neumayer Station contain up to 700 ng/l of total iodine, representing a sufficient reservoir for these extraordinarily high IO concentrations.

  10. Responses of Antarctic Oscillation to global warming

    Science.gov (United States)

    Feng, S.

    2015-12-01

    The Antarctic Oscillation (AAO) is the major annular mode dominates the spatiotemporal variability of the atmospheric circulation in the Southern Hemisphere. This study examined the sensitivity of AAO to future warming by analyzing the outputs of 34 state-of-the-art climate models participating in phase 5 of the Coupled Model Intercomparion Project (CMIP5). The model simulations include the stabilized (RCP4.5) and business as usual (RCP8.5) scenarios as well as the idealized 1% per year increase in atmospheric CO2 to quadrupling (1pctCO2) and an instantaneous quadrupling of CO2 (abrupt4xCO2). We show that the CMIP5 models on average simulate increases in the AAO in every season by 2100 under the RCP4.5 and RCP8.5 scenarios. However, due to the impacts of ozone, aerosol and land use changes, the amplitudes of the projected changes in AAO to future climate scenarios are quit different on different seasons. After the impact of ozone, aerosol and land use changes were removed; it was found that the impact of greenhouse gases (GHGs) on AAO is similar on all seasons. The increases of AAO are accelerating following the increase of GHGs. Our results are also consistent with the simulations of 1pctCO2 and abrupt4xCO2.

  11. Ionospheric irregularities at Antarctic using GPS measurements

    Indian Academy of Sciences (India)

    Sunita Tiwari; Amit Jain; Shivalika Sarkar; Sudhir Jain; A K Gwal

    2012-04-01

    The purpose of this work is to study the behaviour of the ionospheric scintillation at high latitude during geomagnetically quiet and disturbed conditions which is one of the most relevant themes in the space weather studies. Scintillation is a major problem in navigation application using GPS and in satellite communication at high latitudes. Severe amplitude fading and strong scintillation affect the reliability of GPS navigational system and satellite communication. To study the effects of the ionospheric scintillations, GPS receiver installed at Antarctic station Maitri (Geog. 70.76°S; 11.74°E) was used. The data is collected by using GISTM 4004A, NOVATEL’S GPS receiver during March 2008. Studies show that percentage occurrence of phase scintillation is well correlated with geomagnetic activity during the observation period. The result also shows that very intense scintillations can degrade GPS based location determination due to loss of lock of satellites. These findings indicate that the dependence of scintillations and irregularity occurrence on geomagnetic activity is associated with the magnetic local time (MLT). Large number of patches are reported and their activity depends on the magnetic activity index.

  12. Automated detection of Antarctic blue whale calls.

    Science.gov (United States)

    Socheleau, Francois-Xavier; Leroy, Emmanuelle; Pecci, Andres Carvallo; Samaran, Flore; Bonnel, Julien; Royer, Jean-Yves

    2015-11-01

    This paper addresses the problem of automated detection of Z-calls emitted by Antarctic blue whales (B. m. intermedia). The proposed solution is based on a subspace detector of sigmoidal-frequency signals with unknown time-varying amplitude. This detection strategy takes into account frequency variations of blue whale calls as well as the presence of other transient sounds that can interfere with Z-calls (such as airguns or other whale calls). The proposed method has been tested on more than 105 h of acoustic data containing about 2200 Z-calls (as found by an experienced human operator). This method is shown to have a correct-detection rate of up to more than 15% better than the extensible bioacoustic tool package, a spectrogram-based correlation detector commonly used to study blue whales. Because the proposed method relies on subspace detection, it does not suffer from some drawbacks of correlation-based detectors. In particular, it does not require the choice of an a priori fixed and subjective template. The analytic expression of the detection performance is also derived, which provides crucial information for higher level analyses such as animal density estimation from acoustic data. Finally, the detection threshold automatically adapts to the soundscape in order not to violate a user-specified false alarm rate. PMID:26627784

  13. Prospects for surviving climate change in Antarctic aquatic species

    Directory of Open Access Journals (Sweden)

    Peck Lloyd S

    2005-06-01

    Full Text Available Abstract Maritime Antarctic freshwater habitats are amongst the fastest changing environments on Earth. Temperatures have risen around 1°C and ice cover has dramatically decreased in 15 years. Few animal species inhabit these sites, but the fairy shrimp Branchinecta gaini typifies those that do. This species survives up to 25°C daily temperature fluctuations in summer and passes winter as eggs at temperatures down to -25°C. Its annual temperature envelope is, therefore around 50°C. This is typical of Antarctic terrestrial species, which exhibit great physiological flexibility in coping with temperature fluctuations. The rapidly changing conditions in the Maritime Antarctic are enhancing fitness in these species by increasing the time available for feeding, growth and reproduction, as well as increasing productivity in lakes. The future problem these animals face is via displacement by alien species from lower latitudes. Such invasions are now well documented from sub-Antarctic sites. In contrast the marine Antarctic environment has very stable temperatures. However, seasonality is intense with very short summers and long winter periods of low to no algal productivity. Marine animals grow slowly, have long generation times, low metabolic rates and low levels of activity. They also die at temperatures between +5°C and +10°C. Failure of oxygen supply mechanisms and loss of aerobic scope defines upper temperature limits. As temperature rises, their ability to perform work declines rapidly before lethal limits are reached, such that 50% of populations of clams and limpets cannot perform essential activities at 2–3°C, and all scallops are incapable of swimming at 2°C. Currently there is little evidence of temperature change in Antarctic marine sites. Models predict average global sea temperatures will rise by around 2°C by 2100. Such a rise would take many Antarctic marine animals beyond their survival limits. Animals have 3 mechanisms for

  14. Complex Geodetic Research in Ukrainian Antarctic Station "Academician Vernadsky" (Years 2002 - 2005, 2013-2014)

    Science.gov (United States)

    Tretyak, Kornyliy; Hlotov, Volodymyr; Holubinka, Yuriy; Marusazh, Khrystyna

    2016-06-01

    In this paper is given an information about complex geodetic research in Ukrainian Antarctic station "Academician Vernadsky". Research were carried by Lviv polytechnic scientists, during Antarctic expeditions in years 2002 - 2005, 2013, 2014. Main objectives of the studies were: (a) study of the islands glaciers surface volumes changes in Antarctic archipelago and Antarctic Peninsula using terestrial laser scaning and digital terrestrial stereophotogrammetry survey; (b) investigation of Penola strain tectonic fault, using the results of precise GNSS observations.

  15. On the Linkage between Antarctic Surface Water Stratification and Global Deep-Water Temperature

    OpenAIRE

    Keeling, R.F.; Visbeck, Martin

    2011-01-01

    The suggestion is advanced that the remarkably low static stability of Antarctic surface waters may arise from a feedback loop involving global deep-water temperatures. If deep-water temperatures are too warm, this promotes Antarctic convection, thereby strengthening the inflow of Antarctic Bottom Water into the ocean interior and cooling the deep ocean. If deep waters are too cold, this promotes Antarctic stratification allowing the deep ocean to warm because of the input of North Atlantic D...

  16. Relative changes in krill abundance inferred from Antarctic fur seal.

    Directory of Open Access Journals (Sweden)

    Tao Huang

    Full Text Available Antarctic krill Euphausia superba is a predominant species in the Southern Ocean, it is very sensitive to climate change, and it supports large stocks of fishes, seabirds, seals and whales in Antarctic marine ecosystems. Modern krill stocks have been estimated directly by net hauls and acoustic surveys; the historical krill density especially the long-term one in the Southern Ocean, however, is unknown. Here we inferred the relative krill population changes along the West Antarctic Peninsula (WAP over the 20th century from the trophic level change of Antarctic fur seal Arctocephalus gazella using stable carbon (δ(13C and nitrogen (δ(15N isotopes of archival seal hairs. Since Antarctic fur seals feed preferentially on krill, the variation of δ(15N in seal hair indicates a change in the proportion of krill in the seal's diets and thus the krill availability in local seawater. For the past century, enriching fur seal δ(15N values indicated decreasing krill availability. This is agreement with direct observation for the past ∼30 years and suggests that the recently documented decline in krill populations began in the early parts of the 20th century. This novel method makes it possible to infer past krill population changes from ancient tissues of krill predators.

  17. The Antarctic ozone depletion caused by Erebus volcano gas emissions

    Science.gov (United States)

    Zuev, V. V.; Zueva, N. E.; Savelieva, E. S.; Gerasimov, V. V.

    2015-12-01

    Heterogeneous chemical reactions releasing photochemically active molecular chlorine play a key role in Antarctic stratospheric ozone destruction, resulting in the Antarctic ozone hole. Hydrogen chloride (HCl) is one of the principal components in these reactions on the surfaces of polar stratospheric clouds (PSCs). PSCs form during polar nights at extremely low temperatures (lower than -78 °C) mainly on sulfuric acid (H2SO4) aerosols, acting as condensation nuclei and formed from sulfur dioxide (SO2). However, the cause of HCl and H2SO4 high concentrations in the Antarctic stratosphere, leading to considerable springtime ozone depletion, is still not clear. Based on the NCEP/NCAR reanalysis data over the last 35 years and by using the NOAA HYSPLIT trajectory model, we show that Erebus volcano gas emissions (including HCl and SO2) can reach the Antarctic stratosphere via high-latitude cyclones with the annual average probability Pbarann. of at least ∼0.235 (23.5%). Depending on Erebus activity, this corresponds to additional annual stratospheric HCl mass of 1.0-14.3 kilotons (kt) and SO2 mass of 1.4-19.7 kt. Thus, Erebus volcano is the natural and powerful source of additional stratospheric HCl and SO2, and hence, the cause of the Antarctic ozone depletion, together with man-made chlorofluorocarbons.

  18. Antarctic ecosystems as models for extraterrestrial surface habitats

    Science.gov (United States)

    Wynn-Williams, D. D.; Edwards, H. G. M.

    2000-09-01

    Surface habitats in Antarctic deserts are near the limits of life on Earth and resemble those hypothesized for early Mars. Cyanobacteria dominate the transient riverbeds, stromatolitic sediments in ice-covered lakes, and endolithic communities in translucent rock. There is still no direct evidence of photosynthetic life on early Mars, but cyanobacteria are amongst the earliest microbes detectable in the fossil record for analogous habitats on Earth. Key biomolecules persist in Antarctic microbial habitats, even after extinction by excessive low temperatures, desiccation and UV-B stress within the Ozone Hole. Pigments (or their fossil residues), such as chlorophyll and the UV-protectants scytonemin, carotene and quinones, are good biomarkers. To show not only their presence but also their micro-spatial distribution in situ, we describe the use of FT-Raman spectroscopy with 1064 nm excitation to avoid autofluorescence from the pigments. We report not only the diversity of biomolecules that we have diagnosed from their unique Raman spectra of Antarctic cyanobacterial communities, but also their functional stratification in endolithic communities. Our analyses of Antarctic habitats show the potential of this remote, non-intrusive technique to probe for buried biomolecules on future Mars missions and in Antarctic Lake Vostok, >4 km beneath the Central Ice Sheet, with implications for the putative analogous sub-ice ocean on Europa.

  19. Ground based observations of Pc3-Pc5 geomagnetic pulsation power at Antarctic McMurdo station

    Directory of Open Access Journals (Sweden)

    C. G. Maclennan

    1998-06-01

    Full Text Available The two horizontal geomagnetic components and, measured by a fluxgate magnetometer at Antarctic McMurdo station (corrected geomagnetic coordinates 80.0° S, 327.5° E, are analyzed for the period May-June 1994; the spectral powers are calculated and integrated over three frequency intervals corresponding to the nominal ranges. The time dependence of those integrated powers and their correlations with northern auroral indices and solar wind speed are considered. The observations are compared with previous results reported from Terra Nova Bay station (located near McMurdo at the same corrected geomagnetic latitude during Antarctic summer intervals. The differences found between the two stations are discussed in terms of the seasonal dependence of geomagnetic field line configurations in the near cusp region.

  20. A consistent data set of Antarctic ice sheet topography, cavity geometry, and global bathymetry

    Directory of Open Access Journals (Sweden)

    R. Timmermann

    2010-12-01

    Full Text Available Sub-ice shelf circulation and freezing/melting rates in ocean general circulation models depend critically on an accurate and consistent representation of cavity geometry. Existing global or pan-Antarctic topography data sets have turned out to contain various inconsistencies and inaccuracies. The goal of this work is to compile independent regional surveys and maps into a global data set. We use the S-2004 global 1-min bathymetry as the backbone and add an improved version of the BEDMAP topography (ALBMAP bedrock topography for an area that roughly coincides with the Antarctic continental shelf. The position of the merging line is individually chosen in different sectors in order to capture the best of both data sets. High-resolution gridded data for ice shelf topography and cavity geometry of the Amery, Fimbul, Filchner-Ronne, Larsen C and George VI Ice Shelves, and for Pine Island Glacier are carefully merged into the ambient ice and ocean topographies. Multibeam survey data for bathymetry in the former Larsen B cavity and the southeastern Bellingshausen Sea have been obtained from the data centers of Alfred Wegener Institute (AWI, British Antarctic Survey (BAS and Lamont-Doherty Earth Observatory (LDEO, gridded, and blended into the existing bathymetry map. The resulting global 1-min Refined Topography data set (RTopo-1 contains self-consistent maps for upper and lower ice surface heights, bedrock topography, and surface type (open ocean, grounded ice, floating ice, bare land surface. The data set is available in NetCDF format from the PANGAEA database at doi:10.1594/pangaea.741917.

  1. RTOPO-1: A consistent dataset for Antarctic ice shelf topography and global ocean bathymetry

    Science.gov (United States)

    Timmermann, Ralph

    2010-05-01

    Sub-ice shelf circulation and freezing/melting rates depend critically on an accurate and consistent representation of cavity geometry (i.e. ice-shelf draft and ocean bathymetry). Existing global or pan-Antarctic data sets have turned out to contain various inconsistencies and inaccuracies. The goal of this work is to compile independent regional fields into a global data set. We use the S-2004 global 1-minute bathymetry as the backbone and add an improved version of the BEDMAP topography for an area that roughly coincides with the Antarctic continental shelf. Locations of the merging line have been carefully adjusted in order to get the best out of each data set. High-resolution gridded data for the Amery, Fimbul, Filchner-Ronne, Larsen C and George VI Ice Shelves and for Pine Island Glacier have been carefully merged into the ambient ice and ocean topographies. Multibeam ship survey data for bathymetry in the former Larsen B cavity and the southeastern Bellingshausen Sea have been obtained from the data centers of Alfred Wegener Institute (AWI), British Antarctic Survey (BAS) and Lamont-Doherty Earth Observatory (LDEO), gridded, and again carefully merged into the existing bathymetry map. The resulting global 1-minute data set contains consistent masks for open ocean, grounded ice, floating ice, and bare land surface. The Ice Shelf Cavern Geometry Team: Anne Le Brocq, Tara Deen, Eugene Domack, Pierre Dutrieux, Ben Galton-Fenzi, Dorothea Graffe, Hartmut Hellmer, Angelika Humbert, Daniela Jansen, Adrian Jenkins, Astrid Lambrecht, Keith Makinson, Fred Niederjasper, Frank Nitsche, Ole Anders Nøst, Lars Henrik Smedsrud, and Walter Smith

  2. Antarctic DNA moving forward: genomic plasticity and biotechnological potential.

    Science.gov (United States)

    Martínez-Rosales, Cecilia; Fullana, Natalia; Musto, Héctor; Castro-Sowinski, Susana

    2012-06-01

    Antarctica is the coldest, driest, and windiest continent, where only cold-adapted organisms survive. It has been frequently cited as a pristine place, but it has a highly diverse microbial community that is continually seeded by nonindigenous microorganisms. In addition to the intromission of 'alien' microorganisms, global warming strongly affects microbial Antarctic communities, changing the genes (qualitatively and quantitatively) potentially available for horizontal gene transfer. Several mobile genetic elements have been described in Antarctic bacteria (including plasmids, transposons, integrons, and genomic islands), and the data support that they are actively involved in bacterial evolution in the Antarctic environment. In addition, this environment is a genomic source for the identification of novel molecules, and many investigators have used culture-dependent and culture-independent approaches to identify cold-adapted proteins. Some of them are described in this review. We also describe studies for the design of new recombinant technologies for the production of 'difficult' proteins. PMID:22360528

  3. Terrestrial 81Kr-Kr ages of Antarctic meteorites

    International Nuclear Information System (INIS)

    The production rate of 38Ar in meteorites-P(38)-has been determined, as a function of the sample's chemical composition, from 81Kr-Kr exposure ages of four eucrite falls. The cosmogenic 78Kr/83Kr ratio is used to estimate the shielding dependence of P(38). From the ''true'' 38Ar exposure ages and the apparent 81Kr-Kr exposure ages of nine Antarctic eucrite finds, terrestrial ages are calculated. The distribution of terrestrial ages of Allan Hills meteorites is discussed. Meteorites from this blue ice field have two sources: Directly deposited falls and meteorites transported to the Allan Hills inside the moving Antarctic ice sheet. During the surface residence time meteorites decompose due to weathering processes. The weathering ''half-life'' is about 1.6 x 105 a. From the different age distributions of Allan Hills and Yamato meteorites, it is concluded that meteorite concentrations of different Antarctic ice fields need different explanations. (author)

  4. Variability in solar irradiance observed at two contrasting Antarctic sites

    Science.gov (United States)

    Petkov, Boyan H.; Láska, Kamil; Vitale, Vito; Lanconelli, Christian; Lupi, Angelo; Mazzola, Mauro; Budíková, Marie

    2016-05-01

    The features of erythemally weighted (EW) and short-wave downwelling (SWD) solar irradiances, observed during the spring-summer months of 2007-2011 at Johann Gregor Mendel (63°48‧S, 57°53‧W, 7 m a.s.l.) and Dome Concordia (75°06‧S, 123°21‧E, 3233 m a.s.l.) stations, placed at the Antarctic coastal region and on the interior plateau respectively, have been analysed and compared to each other. The EW and SWD spectral components have been presented by the corresponding daily integrated values and were examined taking into account the different geographic positions and different environmental conditions at both sites. The results indicate that at Mendel station the surface solar irradiance is strongly affected by the changes in the cloud cover, aerosols and albedo that cause a decrease in EW between 20% and 35%, and from 0% to 50% in SWD component, which contributions are slightly lower than the seasonal SWD variations evaluated to be about 71%. On the contrary, the changes in the cloud cover features at Concordia station produce only a 5% reduction of the solar irradiance, whilst the seasonal oscillations of 94% turn out to be the predominant mode. The present analysis leads to the conclusion that the variations in the ozone column cause an average decrease of about 46% in EW irradiance with respect to the value found in the case of minimum ozone content at each of the stations. In addition, the ratio between EW and SWD spectral components can be used to achieve a realistic assessment of the radiation amplification factor that quantifies the relationship between the atmospheric ozone and the surface UV irradiance.

  5. Model decay in the Australia-Antarctic basin

    Energy Technology Data Exchange (ETDEWEB)

    Weijer, Wilbert [Los Alamos National Laboratory; Gille, Sarah T [UCSD; Vivier, Frederic [LOCEAN-IPSL

    2008-01-01

    The barotropic intraseasonal variability in the Australia-Antarctic Basin (AAB) is studied in terms of the excitation and decay of topographically-trapped barotropic modes. The main objective is to reconcile two widely differing estimates of the decay rate of SSH anomalies in the AAB that are assumed to be related to barotropic modes. First, an Empirical Orthogonal Function (EOF) analysis is applied to almost 15 years of altimeter data. The analysis suggests that several modes are involved in the variability of the AAB, each related to distinct areas with (almost) closed contours of potential vorticity. Second, the dominant normal modes of the AAB are determined in a barotropic shallow-water (SW) model. These stationary modes are confined by the closed contours of potential vorticity that surround the eastern AAB, and the crest of the Southeast Indian Ridge. For reasonable values of horizontal eddy viscosity and bottom friction, their decay time scale is of the order of several weeks. Third, the SW model is forced with realistic winds and integrated for several years. Projection of the modal velocity patterns onto the output fields shows that the barotropic modes are indeed excited in the model, and that they decay slowly on the frictional O(3 weeks) time scale. However, the SSH anomalies in the modal areas display rapid O(4 days) decay. Additional analysis shows that this rapid decay reflects the adjustment of unbalanced flow components through the emission of Rossby waves. Resonant excitation of the dominant free modes accounts for about 20% of the SSH variability in the forced model run. Other mechanisms are suggested to explain the region of high SSH variability in the AAB.

  6. Modeling Antarctic subglacial lake filling and drainage cycles

    Directory of Open Access Journals (Sweden)

    C. F. Dow

    2015-11-01

    Full Text Available The growth and drainage of active subglacial lakes in Antarctica has previously been inferred from analysis of ice surface altimetry data. We use a subglacial hydrology model applied to a synthetic Antarctic ice stream to determine internal controls on the filling and drainage of subglacial lakes and their impact on ice stream dynamics. Our model outputs suggest that the highly constricted subglacial environment of the ice stream, combined with relatively high rates of water flow funneled from large catchments, can combine to create a system exhibiting slow-moving pressure waves. Over a period of years, the accumulation of water in the ice stream onset region results in a buildup of pressure creating temporary channels, which then evacuate the excess water. This increased flux of water through the ice stream drives lake growth. As the water body builds up, it too steepens the hydraulic gradient and allows greater flux out of the overdeepened lake basin. Eventually this flux is large enough to create channels that cause the lake to drain. Due to the presence of the channels, the drainage of the lake causes high water pressures around 50 km downstream of the lake rather than immediately in the vicinity of the overdeepening. Following lake drainage, channels again shut down. Lake drainage depends on the internal hydrological development in the wider system and therefore does not directly correspond to a particular water volume or depth. This creates a highly temporally and spatially variable system, which is of interest for assessing the importance of subglacial lakes in ice stream hydrology and dynamics.

  7. Antarctic Ozone Hole on September 17, 2001

    Science.gov (United States)

    2002-01-01

    Satellite data show the area of this year's Antarctic ozone hole peaked at about 26 million square kilometers-roughly the size of North America-making the hole similar in size to those of the past three years, according to scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA). Researchers have observed a leveling-off of the hole size and predict a slow recovery. Over the past several years the annual ozone hole over Antarctica has remained about the same in both its size and in the thickness of the ozone layer. 'This is consistent with human-produced chlorine compounds that destroy ozone reaching their peak concentrations in the atmosphere, leveling off, and now beginning a very slow decline,' said Samuel Oltmans of NOAA's Climate Monitoring and Diagnostics Laboratory, Boulder, Colo. In the near future-barring unusual events such as explosive volcanic eruptions-the severity of the ozone hole will likely remain similar to what has been seen in recent years, with year-to-year differences associated with meteorological variability. Over the longer term (30-50 years) the severity of the ozone hole in Antarctica is expected to decrease as chlorine levels in the atmosphere decline. The image above shows ozone levels on Spetember 17, 2001-the lowest levels observed this year. Dark blue colors correspond to the thinnest ozone, while light blue, green, and yellow pixels indicate progressively thicker ozone. For more information read: 2001 Ozone Hole About the Same Size as Past Three Years. Image courtesy Greg Shirah, GSFC Scientific Visualization Studio, based on data from the TOMS science team

  8. Viral distribution and activity in Antarctic waters

    Science.gov (United States)

    Guixa-Boixereu, Núria; Vaqué, Dolors; Gasol, Josep M.; Sánchez-Cámara, Jaime; Pedrós-Alió, Carlos

    Variability in abundance of virus-like particles (VLP), VLP decay rates and prokaryotic mortality due to viral infection were determined in three Antarctic areas: Bellingshausen Sea, Bransfield Strait and Gerlache Strait, during December 1995 and February 1996. VLP abundance showed very small spatial variability in the three areas (7×10 6-2×10 7 VLP ml -1). VLP abundance, on the other hand, decreased one order of magnitude from the surface to the bottom, in two stations where deep vertical profiles were sampled. Low seasonal variability in VLP abundance was found when comparing each area separately. Diel VLP variability was also very low. VLP abundance showed the lowest values when solar irradiation was maximal, in two of the three stations where diel cycles were examined. Viral decay rates (VDR) were determined using KCN in two kinds of experiments. Type 1 experiments were performed in 6 stations to determine viral decay. Type 2 experiments were carried out in 2 stations to examine the influence of temperature and organic matter concentration on viral decay. VDR was not influenced by these parameters. Prokaryotic mortality due to viral infection was always higher than that due to bacterivores in the stations where both factors of prokaryotic mortality were measured. Viral infection accounted for all the prokaryotic heterotrophic production in Bellingshausen Sea and Gerlache Strait and for half of the prokaryotic heterotrophic production in Bransfield Strait. These high values of prokaryotic mortality due to viral infection are difficult to reconcile in nature, and more work is necessary to determine the mechanisms involved in the disappearance of viruses.

  9. Microbiology and Geochemistry of Antarctic Paleosols

    Science.gov (United States)

    Mahaney, W. C.; Malloch, D.; Hancock, R. G. V.; Campbell, I. B.; Sheppard, D.

    2000-08-01

    Samples of ancient soils from horizons in paleosols from the Quartermain Mountains (Aztec and New Mountain areas of the Antarctic Dry Valleys) were analyzed for their chemical composition and microbiology to determine the accumulation and movement of salts and other soluble constituents. The salt concentrations are of special interest because they are considered to be a function of age, derived in part from nearby oceanic and high altitude atmospheric sources. The geochemistry of ancient Miocene-age paleosols in these areas is the direct result of the deposition and weathering of till, derived principally from dolerite and sandstone source rock, in association with airborne-influxed salts. Paleosols nearer the coast have greater contents of chlorine, and farther inland near the Inland Ice Sheet, nitrogen tends to increase on a relative basis. The accumulation and vertical distribution of salts and other soluble chemical elements indicate relative amounts of movement in the profile over long periods of time, to the order of several million years. Iron, both in total concentration and in the form of various extracts, indicates it can be used as a geochronometer to assess the buildup of goethite plus hematite over time in the paleosols. Trends for ferrihydrite, a partially soluble Fe-hydroxide, shows limited profile translocation that might be related to the movement of salt. Six of the eight selected subsamples from paleosol horizons in three soil profiles contained nil concentrations of bacteria and fungi. However, two horizons at depths of between three to eight centimeters yielded several colonies of the fungi Beauveria bassiana and Penicillium spp., indicating some input of organic carbon. Beauveria bassiana is often reported in association with insects and is used commercially for the biological control of some insect pests. Penicillium species are commonly isolated from Arctic, temperate and tropical soils and are known to utilize a wide variety of organic

  10. Satellite mapping and automated feature extraction: Geographic information system-based change detection of the Antarctic coast

    Science.gov (United States)

    Kim, Kee-Tae

    Declassified Intelligence Satellite Photograph (DISP) data are important resources for measuring the geometry of the coastline of Antarctica. By using the state-of-art digital imaging technology, bundle block triangulation based on tie points and control points derived from a RADARSAT-1 Synthetic Aperture Radar (SAR) image mosaic and Ohio State University (OSU) Antarctic digital elevation model (DEM), the individual DISP images were accurately assembled into a map quality mosaic of Antarctica as it appeared in 1963. The new map is one of important benchmarks for gauging the response of the Antarctic coastline to changing climate. Automated coastline extraction algorithm design is the second theme of this dissertation. At the pre-processing stage, an adaptive neighborhood filtering was used to remove the film-grain noise while preserving edge features. At the segmentation stage, an adaptive Bayesian approach to image segmentation was used to split the DISP imagery into its homogenous regions, in which the fuzzy c-means clustering (FCM) technique and Gibbs random field (GRF) model were introduced to estimate the conditional and prior probability density functions. A Gaussian mixture model was used to estimate the reliable initial values for the FCM technique. At the post-processing stage, image object formation and labeling, removal of noisy image objects, and vectorization algorithms were sequentially applied to segmented images for extracting a vector representation of coastlines. Results were presented that demonstrate the effectiveness of the algorithm in segmenting the DISP data. In the cases of cloud cover and little contrast scenes, manual editing was carried out based on intermediate image processing and visual inspection in comparison of old paper maps. Through a geographic information system (GIS), the derived DISP coastline data were integrated with earlier and later data to assess continental scale changes in the Antarctic coast. Computing the area of

  11. Hydrochemical characteristic of different modifications of Antarctic waters

    Science.gov (United States)

    Batrak, K. V.

    2008-06-01

    The report considers the distribution of several hydrochemical components (dissolved oxygen, mineral phosphorus, dissolved silicon, and nitrate nitrogen) depending on the disposition of different structural water modifications constituting the unified Antarctic structural type. It is shown that the character of the silicon distribution in the waters of the South Polar zone is mainly determined by large-scale circulation features. The distribution of mineral phosphorus and nitrate nitrogen is characterized by a certain patchiness related to the photosynthesis intensity. An attempt was made to follow the supply and transformation of dissolved silicon, nitrates, and phosphates in the Antarctic.

  12. Brain and sense organ anatomy and histology of the Falkland Islands mullet, Eleginops maclovinus (Eleginopidae), the sister group of the Antarctic notothenioid fishes (Perciformes: Notothenioidei).

    Science.gov (United States)

    Eastman, Joseph T; Lannoo, Michael J

    2008-01-01

    The perciform notothenioid fish Eleginops maclovinus, representing the monotypic family Eleginopidae, has a non-Antarctic distribution in the Falkland Islands and southern South America. It is the sister group of the five families and 103 species of Antarctic notothenioids that dominate the cold shelf waters of Antarctica. Eleginops is the ideal subject for documenting the ancestral morphology of nervous and sensory systems that have not had historical exposure to the unusual Antarctic thermal and light regimes, and for comparing these systems with those of the phyletically derived Antarctic species. We present a detailed description of the brain and cranial nerves of Eleginops and ask how does the neural and sensory morphology of this non-Antarctic notothenioid differ from that seen in the phyletically derived Antarctic notothenioids? The brain of Eleginops is similar to those of visually oriented temperate and tropical perciforms. The tectum is smaller but it has well-developed olfactory and mechanoreceptive lateral line areas and a large, caudally projecting corpus cerebellum. Eye diameter is about twofold smaller in Eleginops than in many Antarctic species. Eleginops has a duplex (rod and cone) retina with single and occasional twin cones conspicuous centrally. Ocular vascular structures include a large choroid rete mirabile and a small lentiform body; a falciform process and hyaloid arteries are absent. The olfactory rosette is oval with 50-55 lamellae, a large number for notothenioids. The inconspicuous bony canals of the cephalic lateral line system are simple with membranous secondary branches that lack neuromasts. In Antarctic species, the corpus cerebellum is the most variable brain region, ranging in size from large and caudally projecting to small and round. "Stalked" brains showing reduction in the size of the telencephalon, tectum, and corpus cerebellum are present in the deep-living artedidraconid Dolloidraco longedorsalis and in most of the deep

  13. Laboratory study of nitrate photolysis in Antarctic snow. II. Isotopic effects and wavelength dependence

    Energy Technology Data Exchange (ETDEWEB)

    Berhanu, Tesfaye A.; Erbland, Joseph; Savarino, Joël [Laboratoire de Glaciologie et Géophysique de l’Environnement, CNRS, F-38041 Grenoble (France); Univ. Grenoble Alpes, LGGE, F-38041 Grenoble (France); Meusinger, Carl; Johnson, Matthew S. [Copenhagen Center for Atmospheric Research (CCAR), Department of Chemistry, University of Copenhagen, Copenhagen (Denmark); Jost, Rémy [Laboratoire de Interdisciplinaire de Physique (LIPHY) Univ. de Grenoble, Grenoble (France); Bhattacharya, S. K. [Research Center for Environmental Changes, Academia Sinica, Nangang, Taipei 115, Taiwan (China)

    2014-06-28

    Atmospheric nitrate is preserved in Antarctic snow firn and ice. However, at low snow accumulation sites, post-depositional processes induced by sunlight obscure its interpretation. The goal of these studies (see also Paper I by Meusinger et al. [“Laboratory study of nitrate photolysis in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry,” J. Chem. Phys. 140, 244305 (2014)]) is to characterize nitrate photochemistry and improve the interpretation of the nitrate ice core record. Naturally occurring stable isotopes in nitrate ({sup 15}N, {sup 17}O, and {sup 18}O) provide additional information concerning post-depositional processes. Here, we present results from studies of the wavelength-dependent isotope effects from photolysis of nitrate in a matrix of natural snow. Snow from Dome C, Antarctica was irradiated in selected wavelength regions using a Xe UV lamp and filters. The irradiated snow was sampled and analyzed for nitrate concentration and isotopic composition (δ{sup 15}N, δ{sup 18}O, and Δ{sup 17}O). From these measurements an average photolytic isotopic fractionation of {sup 15}ε = (−15 ± 1.2)‰ was found for broadband Xe lamp photolysis. These results are due in part to excitation of the intense absorption band of nitrate around 200 nm in addition to the weaker band centered at 305 nm followed by photodissociation. An experiment with a filter blocking wavelengths shorter than 320 nm, approximating the actinic flux spectrum at Dome C, yielded a photolytic isotopic fractionation of {sup 15}ε = (−47.9 ± 6.8)‰, in good agreement with fractionations determined by previous studies for the East Antarctic Plateau which range from −40 to −74.3‰. We describe a new semi-empirical zero point energy shift model used to derive the absorption cross sections of {sup 14}NO{sub 3}{sup −} and {sup 15}NO{sub 3}{sup −} in snow at a chosen temperature. The nitrogen isotopic fractionations obtained by applying

  14. Laboratory study of nitrate photolysis in Antarctic snow. II. Isotopic effects and wavelength dependence

    International Nuclear Information System (INIS)

    Atmospheric nitrate is preserved in Antarctic snow firn and ice. However, at low snow accumulation sites, post-depositional processes induced by sunlight obscure its interpretation. The goal of these studies (see also Paper I by Meusinger et al. [“Laboratory study of nitrate photolysis in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry,” J. Chem. Phys. 140, 244305 (2014)]) is to characterize nitrate photochemistry and improve the interpretation of the nitrate ice core record. Naturally occurring stable isotopes in nitrate (15N, 17O, and 18O) provide additional information concerning post-depositional processes. Here, we present results from studies of the wavelength-dependent isotope effects from photolysis of nitrate in a matrix of natural snow. Snow from Dome C, Antarctica was irradiated in selected wavelength regions using a Xe UV lamp and filters. The irradiated snow was sampled and analyzed for nitrate concentration and isotopic composition (δ15N, δ18O, and Δ17O). From these measurements an average photolytic isotopic fractionation of 15ε = (−15 ± 1.2)‰ was found for broadband Xe lamp photolysis. These results are due in part to excitation of the intense absorption band of nitrate around 200 nm in addition to the weaker band centered at 305 nm followed by photodissociation. An experiment with a filter blocking wavelengths shorter than 320 nm, approximating the actinic flux spectrum at Dome C, yielded a photolytic isotopic fractionation of 15ε = (−47.9 ± 6.8)‰, in good agreement with fractionations determined by previous studies for the East Antarctic Plateau which range from −40 to −74.3‰. We describe a new semi-empirical zero point energy shift model used to derive the absorption cross sections of 14NO3− and 15NO3− in snow at a chosen temperature. The nitrogen isotopic fractionations obtained by applying this model under the experimental temperature as well as considering the shift in width

  15. A Biophysical and Economic Profile of South Georgia and the South Sandwich Islands as Potential Large-Scale Antarctic Protected Areas.

    Science.gov (United States)

    Rogers, Alex D; Yesson, Christopher; Gravestock, Pippa

    2015-01-01

    The current hiatus in the establishment of a network of marine protected areas (MPAs) in the Antarctic means that other routes to conservation are required. The protection of overseas territories in the Antarctic and sub-Antarctic represents one way to advance the initiation of such a network. This review of the physical and biological features of the United Kingdom (U.K.) overseas territories of South Georgia and South Sandwich Islands (SGSSI) is undertaken to estimate the importance of the islands in terms of marine conservation in the Southern Ocean and globally. The economy and management of SGSSI are also analysed, and the question of whether the islands already have sufficient protection to constitute part of an Antarctic network of MPAs is assessed. The SGSSI comprise unique geological and physical features, a diverse marine biota, including a significant proportion of endemic species and globally important breeding populations of marine predators. Regardless of past exploitation of biotic resources, such as seals, whales and finfish, SGSSI would make a significant contribution to biological diversity in an Antarctic network of MPAs. At present, conservation measures do not adequately protect all of the biological features that render the islands so important in terms of conservation at a regional and global level. However, a general lack of data on Antarctic marine ecosystems (particularly needed for SGSSSI) makes it difficult to assess this fully. One barrier to achieving more complete protection is the continuing emphasis on fishing effort in these waters by U.K. government. Other non-U.K. Antarctic overseas territories of conservation importance are also compromised as MPAs because of the exploitation of fisheries resources in their waters. The possible non-use values of SGSSI as well as the importance of ecosystem services that are indirectly used by people are outlined in this review. Technology is improving the potential for management of remote MPAs

  16. Persistent organohalogen contaminant burdens in Antarctic krill (Euphausia superba) from the eastern Antarctic sector: A baseline study

    International Nuclear Information System (INIS)

    A baseline for persistent organohalogen compound (POC) accumulation in the Antarctic keystone species, Antarctic krill (Euphausia superba) has been established for a 50 deg. longitudinal range of the eastern Antarctic sector. Samples of adult krill, caught from 12 sites distributed between 30 deg. and 80 deg. E (60-70 deg. S), were analysed for > 100 organohalogen compounds including chlorinated pesticides, polychlorinated biphenyls (PCBs), polybrominated organic compounds and polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs). Organochlorine pesticides dominated measured krill contaminant burdens with hexachlorobenzene (HCB) as the single most abundant compound quantified. Krill HCB concentrations were comparable to those detected at this trophic level in both the Arctic and temperate northwest Atlantic, lending support for the hypothesis that HCB will approach global equilibrium at a faster rate than other POCs. Para, para'-dichlorodiphenylethene (p,p'-DDE) was detected at notable concentrations. Measurements of DDT and its degradation products provide an important baseline for monitoring the temporal and geographical influence of renewed, DDT usage for malaria-control in affected southern hemisphere countries. In contrast to the Arctic, PCBs did not feature prominently in contaminant burdens of Antarctic krill. The major commercial polybrominated diphenyl ether (PBDE) congeners -99 and -47 were quantified at low background levels with clear concentration spikes observed at around 70 deg. E , in the vicinity of modern, active research stations. The likelihood that local anthropogenic activities are supplementing low PBDE levels, delivered otherwise primarily via long range environmental transport, is discussed. The suspected naturally occurring brominated organic compound, 2,4,6-tribromoanisole (TBA), was a ubiquitous contaminant in all samples whereas the only PCDD/Fs quantifiable were trace levels of octachlorodibenzo-p-dioxin (OCDD) and 1,2,3

  17. Southern elephant seals from Kerguelen Islands confronted by Antarctic Sea ice. Changes in movements and in diving behaviour

    Science.gov (United States)

    Bailleul, Frédéric; Charrassin, Jean-Benoıˆt; Ezraty, Robert; Girard-Ardhuin, Fanny; McMahon, Clive R.; Field, Iain C.; Guinet, Christophe

    2007-02-01

    The behaviour of southern elephant seals from Kerguelen Island ( 49∘50'S, 70∘30'E) was investigated in relation to the oceanographic regions of the Southern Ocean. The oceanographic and the seal behaviour data, including location and diving activity, were collected using a new generation of satellite-relayed devices measuring and transmitting pressure, temperature, and salinity along with locations. Dive duration, maximum diving depth, time spent at the bottom of the dives, and shape of dive profiles were compared between male and female seals, and were related to the oceanographic characteristics of areas prospected by the seals. Most animals travelled to the Antarctic shelf. However, during winter, adult females travelled away from the continent, remained and foraged within the marginal sea-ice zone, while juvenile males remained within the pack ice to forage mainly on the Antarctic shelf. Therefore, as the ice expanded females appeared to shift from benthic to pelagic foraging farther north, while males continued to forage almost exclusively benthically on the continental shelf. This difference is likely related to the different energetic requirements between the two sexes, but also may be related to pregnant females having to return to Kerguelen in early spring in order to give birth and successfully raise their pups, while males can remain in the ice. Our results show an important link between elephant seals and Antarctic sea ice and suggest that changes in sea-ice conditions could strongly affect the behaviour of this species.

  18. Effect of Cd on GSH and GSH-related enzymes of Chlamydomonas sp. ICE-L existing in Antarctic ice

    Institute of Scientific and Technical Information of China (English)

    DING Yu; MIAO Jin-lai; LI Guang-you; WANG Quan-fu; KAN Guang-feng; WANG Guo-dong

    2005-01-01

    Glutathione(GSH) and GSH-related enzymes play a great role in protecting organisms from oxidative damage. The GSH level and GSH-related enzymes activities were investigated as well as the growth yield and malonyldialdehyde(MDA) content in the Antarctic ice microalga Chlamydomonas sp. ICE-L exposure to the different cadmium concentration in this paper. The results showed that the higher concentration Cd inhibited the growth of ICE-L significantly and Cd would induce formation of MDA. At the same time, it is clear that GSH level, glutathione peroxidases(GPx) activity and glutathione S-transferases(GST), activity were higher in ICE-L exposed to Cd than the control. But GR activity dropped notably when ICE-L were cultured in the medium containing Cd. Increase of GSH level, GPx and GST activities acclimate to oxidative stress induced by Cd and protect Antarctic ice microalga Chlamydomonas sp. ICE-L from toxicity caused by Cd exposure. These parameters may be used to assess the biological impact of Cd in the Antarctic pole region environment.

  19. Transformations of landscape and peat-forming ecosystems in response to late Holocene climate change in the western Antarctic Peninsula

    Science.gov (United States)

    Yu, Zicheng; Beilman, David W.; Loisel, Julie

    2016-07-01

    We used subfossil mosses and peats to document changes in regional climate, cryosphere, and terrestrial ecosystems in the western Antarctic Peninsula at ~65°S latitude. We find that most peat forming ecosystems have initiated since 2800 cal B.P., in response to warmer summers and increasing summer insolation. The period at 900-600 cal B.P. was coldest as indicated by ice advance, abundance of kill ages from ice-entombed mosses exposed recently from retreating glacial ice, and apparent gap in peatbank initiation. Furthermore, the discovery of a novel Antarctic hairgrass (Deschampsia antarctica) peatland at 2300-1200 cal B.P. from the mainland Antarctic Peninsula suggests a much warmer climate than the present. A warming and wetting climate in the 1980s caused very high carbon accumulation in a Polytrichum strictum moss peatbank. Our results document dramatic transformations of landscape and ecosystems in response to past warmer climate, providing a telltale sign for what may come in the future.

  20. Diurnal Variation of Soil Heat Flux at an Antarctic Local Area during Warmer Months

    Directory of Open Access Journals (Sweden)

    Marco Alves

    2016-01-01

    Full Text Available Soil heat flux (G is one term in the energy balance equation, and it can be particularly important in regions with arid, bare, or thinly vegetated soil surfaces. However, in remote areas such as the Antarctic, this measurement is not routinely performed. The analysis of observational data collected by the ETA Project at the Brazilian Antarctic Station from December 2013 to March 2014 showed that, for the total daily energy flux, the surface soil flux heats the deeper soil layers during December and January and G acts as a heat source to the outer soil layers during February and March. With regard to daytime energy flux, G acts as a source of heat to the deeper layers. During the night-time, the soil is a heat source to the shallower soil layers and represents at least 29% of the net night-time radiation. A relatively simple method—the objective hysteresis method (OHM—was successfully applied to determine the surface soil heat flux using net radiation observations. A priori, the OHM coefficients obtained in this study may only be used for short-time parameterizations and for filling data gaps at this specific site.

  1. Spurious barometric pressure acceleration in Antarctica and propagation into GRACE Antarctic mass change estimates

    Science.gov (United States)

    Kim, Byeong-Hoon; Eom, Jooyoung; Seo, Ki-Weon; Wilson, Clark R.

    2016-06-01

    Apparent acceleration in GRACE Antarctic ice mass time series may reflect both ice discharge and surface mass balance contributions. However, a recent study suggests there is also contamination from errors in atmospheric pressure de-aliasing fields (ECMWF operational products) used during GRACE data processing. To further examine this question, we compare GRACE atmospheric pressure de-aliasing (GAA) fields with in-situ surface pressure data from coastal and inland stations. Differences between the two are likely due to GAA errors, and provide a measure of error in GRACE solutions. Time series of differences at individual weather stations are fit to four presumed error components: annual sinusoids, a linear trend, an acceleration term, and jumps at times of known ECMWF model changes. Using data from inland stations, we estimate that atmospheric pressure error causes an acceleration error of about +7.0 Gt/yr2, which is large relative to prior GRACE estimates of Antarctic ice mass acceleration in the range of -12 to -14 Gt/yr2. We also estimate apparent acceleration rates from other barometric pressure (reanalysis) fields, including ERA-Interim, MERRA and NCEP/DOE. When integrated over East Antarctica, the four mass acceleration estimates (from GAA and the three reanalysis fields) vary considerably (by ˜2-16 Gt/yr2). This shows the need for further effort to improve atmospheric mass estimates in this region of sparse in situ observations, in order to use GRACE observations to measure ice mass acceleration and related sea level change.

  2. Dating Antarctic soils using atmosphere-derived 10Be and nitrate

    International Nuclear Information System (INIS)

    Because they are slow forming, Antarctic soils have the potential to yield considerable climatic information from the past c.20 m.y. However, these soils have proved difficult to date absolutely by conventional means. Here we present a novel approach to the problem, based on atmosphere-derived 10Be and nitrate contents. In situations where medium to long term deposition rates can be reasonably estimated from ice core data, the total nitrate inventory in an Antarctic soil can place constraints on its formation age. 10Be radioactive decay may then be used, assuming steady state equilibrium, to further refine the age profile. We have applied such models to a complex soil from the Taylor Valley region in South Victoria Land, deriving an overall nitrate inventory age of c. 18 Ma, and 10Be decay ages for the upper and middle layers of c.15 and c.17 Ma, respectively. These results are consistent with the >10 Ma age of the soil deduced from stratigraphic and geomorphological information. (author). 28 refs., 4 figs., 2 tabs

  3. MAGIC-DML: Mapping/Measuring/Modeling Antarctic Geomorphology & Ice Change in Dronning Maud Land

    Science.gov (United States)

    Rogozhina, Irina; Bernales, Jorge; Newall, Jennifer; Stroeven, Arjen; Harbor, Jonathan; Glasser, Neil; Fredin, Ola; Fabel, Derek; Hättestrand, Class; Lifton, Nat

    2016-04-01

    Reconstructing and predicting the response of the Antarctic Ice Sheet to climate change is one of the major challenges facing the Earth Science community. There are critical gaps in our knowledge of past changes in ice elevation and extent in many regions of East Antarctica, including a large area of Dronning Maud Land. An international Swedish-UK-US-Norwegian-German project MAGIC-DML aims to reconstruct the timing and pattern of ice surface elevation (thus ice sheet volume) fluctuations since the mid-Pliocene warm period on the Dronning Maud Land margin of the East Antarctic Ice Sheet. A combination of remotely sensed geomorphological mapping, field investigations, surface exposure dating and numerical modelling are being used in an iterative manner to produce a comprehensive reconstruction of the glacial history of Dronning Maud Land. Here we present the results from the first phase of this project, which involves high-resolution numerical simulations of the past glacial geometries and mapping of the field area using historic and recent aerial imagery together with a range of satellite acquired data.

  4. Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene

    Science.gov (United States)

    Levy, Richard; Harwood, David; Florindo, Fabio; Sangiorgi, Francesca; Tripati, Robert; von Eynatten, Hilmar; Gasson, Edward; Kuhn, Gerhard; Tripati, Aradhna; DeConto, Robert; Fielding, Christopher; Field, Brad; Golledge, Nicholas; McKay, Robert; Naish, Timothy; Olney, Matthew; Pollard, David; Schouten, Stefan; Talarico, Franco; Warny, Sophie; Willmott, Veronica; Acton, Gary; Panter, Kurt; Paulsen, Timothy; Taviani, Marco; SMS Science Team; Acton, Gary; Askin, Rosemary; Atkins, Clifford; Bassett, Kari; Beu, Alan; Blackstone, Brian; Browne, Gregory; Ceregato, Alessandro; Cody, Rosemary; Cornamusini, Gianluca; Corrado, Sveva; DeConto, Robert; Del Carlo, Paola; Di Vincenzo, Gianfranco; Dunbar, Gavin; Falk, Candice; Field, Brad; Fielding, Christopher; Florindo, Fabio; Frank, Tracy; Giorgetti, Giovanna; Grelle, Thomas; Gui, Zi; Handwerger, David; Hannah, Michael; Harwood, David M.; Hauptvogel, Dan; Hayden, Travis; Henrys, Stuart; Hoffmann, Stefan; Iacoviello, Francesco; Ishman, Scott; Jarrard, Richard; Johnson, Katherine; Jovane, Luigi; Judge, Shelley; Kominz, Michelle; Konfirst, Matthew; Krissek, Lawrence; Kuhn, Gerhard; Lacy, Laura; Levy, Richard; Maffioli, Paola; Magens, Diana; Marcano, Maria C.; Millan, Cristina; Mohr, Barbara; Montone, Paola; Mukasa, Samuel; Naish, Timothy; Niessen, Frank; Ohneiser, Christian; Olney, Mathew; Panter, Kurt; Passchier, Sandra; Patterson, Molly; Paulsen, Timothy; Pekar, Stephen; Pierdominici, Simona; Pollard, David; Raine, Ian; Reed, Joshua; Reichelt, Lucia; Riesselman, Christina; Rocchi, Sergio; Sagnotti, Leonardo; Sandroni, Sonia; Sangiorgi, Francesca; Schmitt, Douglas; Speece, Marvin; Storey, Bryan; Strada, Eleonora; Talarico, Franco; Taviani, Marco; Tuzzi, Eva; Verosub, Kenneth; von Eynatten, Hilmar; Warny, Sophie; Wilson, Gary; Wilson, Terry; Wonik, Thomas; Zattin, Massimiliano

    2016-03-01

    Geological records from the Antarctic margin offer direct evidence of environmental variability at high southern latitudes and provide insight regarding ice sheet sensitivity to past climate change. The early to mid-Miocene (23-14 Mya) is a compelling interval to study as global temperatures and atmospheric CO2 concentrations were similar to those projected for coming centuries. Importantly, this time interval includes the Miocene Climatic Optimum, a period of global warmth during which average surface temperatures were 3-4 °C higher than today. Miocene sediments in the ANDRILL-2A drill core from the Western Ross Sea, Antarctica, indicate that the Antarctic ice sheet (AIS) was highly variable through this key time interval. A multiproxy dataset derived from the core identifies four distinct environmental motifs based on changes in sedimentary facies, fossil assemblages, geochemistry, and paleotemperature. Four major disconformities in the drill core coincide with regional seismic discontinuities and reflect transient expansion of grounded ice across the Ross Sea. They correlate with major positive shifts in benthic oxygen isotope records and generally coincide with intervals when atmospheric CO2 concentrations were at or below preindustrial levels (˜280 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for substantial ice mass loss during episodes of high (˜500 ppm) atmospheric CO2. These new drill core data and associated ice sheet modeling experiments indicate that polar climate and the AIS were highly sensitive to relatively small changes in atmospheric CO2 during the early to mid-Miocene.

  5. Subduction of Pacific Antarctic Intermediate Water in an eddy-resolving model

    Science.gov (United States)

    Hiraike, Yuri; Tanaka, Yukio; Hasumi, Hiroyasu

    2016-01-01

    The subduction process of Pacific Antarctic Intermediate Water (PAAIW) in the Pacific is investigated using output from an eddy-resolving ocean model. Focus is on contribution of eddies to the subduction process. To separate the subduction rate into contributions by eddies and mean flows, the temporal residual mean (TRM) velocity is used. In the mean subduction rate, lateral induction caused by the strong eastward flow of the Antarctic Circumpolar Current (ACC) is dominant. The largest rate is located in the Drake Passage. The estimated eddy-induced subduction rate is comparable with the mean subduction rate, and it tends to cancel the vertical mean component in many regions. In the west of the Drake Passage, however, the eddy-induced subduction is larger than the vertical mean component, and this eddy-induced subduction was not detected in previous studies using the thickness diffusion parameterization and an eddy-permitting model. Results of idealized sensitivity studies to model resolution suggest that the subduction rate would be larger using a model with higher vertical resolution. Therefore, the vertical resolution should be paid more attention in model studies investigating eddy-induced subduction, and not just the horizontal resolution.

  6. Mass Balance Changes and Ice Dynamics of Greenland and Antarctic Ice Sheets from Laser Altimetry

    Science.gov (United States)

    Babonis, G. S.; Csatho, B.; Schenk, T.

    2016-06-01

    During the past few decades the Greenland and Antarctic ice sheets have lost ice at accelerating rates, caused by increasing surface temperature. The melting of the two big ice sheets has a big impact on global sea level rise. If the ice sheets would melt down entirely, the sea level would rise more than 60 m. Even a much smaller rise would cause dramatic damage along coastal regions. In this paper we report about a major upgrade of surface elevation changes derived from laser altimetry data, acquired by NASA's Ice, Cloud and land Elevation Satellite mission (ICESat) and airborne laser campaigns, such as Airborne Topographic Mapper (ATM) and Land, Vegetation and Ice Sensor (LVIS). For detecting changes in ice sheet elevations we have developed the Surface Elevation Reconstruction And Change detection (SERAC) method. It computes elevation changes of small surface patches by keeping the surface shape constant and considering the absolute values as surface elevations. We report about important upgrades of earlier results, for example the inclusion of local ice caps and the temporal extension from 1993 to 2014 for the Greenland Ice Sheet and for a comprehensive reconstruction of ice thickness and mass changes for the Antarctic Ice Sheets.

  7. Measurements of nitric oxide and total reactive nitrogen in the Antarctic stratosphere: Observations and chemical implications

    International Nuclear Information System (INIS)

    Measurements of NO and the sum of reactive nitrogen species, NOy, were made as part of the Airborne Antarctic Ozone Experiment (AAOE) on flights of the NASA ER-2 aircraft over the Antarctic continent. Reactive nitrogen species include NO,NO2, NO3, N2O5, HNO3, and ClONO2. The technique utilized the conversion of NOy components to NO on a gold catalyst and the subsequent detection of NO by the chemiluminescent reaction of NO with O3. NO was measured on two of the flights by removing the catalyst from the sample line. The boundary of a chemically perturbed region (CPR) above the continent occurred on average near 66 degree S as indicated by a sharp increase in the level of ClO. Outside or equatorward of the CPR, NOy mixing ratios ranged between 6 and 12 parts per billion by volume (ppbv), with values increasing with latitude. At the edge of the CPR, large latitude gradients of NOyand NO were found with values decreasing poleward. Total NOy levels dropped to 4 ppbv or less within 5 degree poleward of the boundary. NO values were 0.1-0.2 ppbv outside and below the detection limit of 0.03 ppbv inside the CPR. The levels of NO and NOy observed preclude a chemical loss of ozone due to reaction with NO

  8. Detection of temperature and sea ice extent changes in the Antarctic and Southern Ocean

    International Nuclear Information System (INIS)

    Some global climate models indicate that future global warming from increased atmospheric concentrations of greenhouse gases may be greatest in the polar regions, over areas where the sea ice cover is reduced. The reduction of sea ice area in the models also gives rise to a strong positive feedback to the warming. From the increase of atmospheric greenhouse gas concentration to date and the results of transient climate models, an estimate of the expected change in the Antarctic temperatures and sea ice extent can be made. The existing data for observed changes in temperatures of the Antarctic and Southern Ocean (extending back to ∼1956 and ∼1945 respectively) are analyzed along with the data of sea ice cover (commencing in 1973) to examine the extent to which the anticipated warming trends and sea ice decrease are being realized. In spite of high temporal and spatial variability, the data does support small significant trends of temperature increase and sea ice cover decrease compatible in magnitude to those expected as a consequence of atmospheric greenhouse gas increase. The seasonal cycle shows a delayed period of autumn-winter sea ice growth with a longer period of open water. This supports a mechanism for positive feedback between decreasing sea ice cover and increasing temperature

  9. Role of Lichens in Weathering and Soil—Forming Processes in Fildes Peninsula,Antarctic

    Institute of Scientific and Technical Information of China (English)

    CHENJIE; GONGZi-TONG

    1995-01-01

    Lichens play an unparalleledly vital role in weathering and soil-forming processes in Antarctic region,In this study some related chemical components and micromorphological analyses have been carried out on the samples of the weathered rocks and the lichens grown on them from Files Peninsula,Antarctic,The results indicatied that the major chemical components in the bioweathering surface layer of the sampled rocks have been obviously altered and the weathering potential in this layer has greatly decreased by and average range around 4.66 percent in 4 samples,In the weathering surface layer ferruginiztion of some minerals in varying degress was seen by means of microscopic examination through the thin section of the weathered rocks,and its products proved to be dominated by hematitie,limonite,goethite and free iron oxides Meanwhile,the study suggested that the dissolution and absorption of lichens by their secretion accelerated the process of calcitization of minerals in the bio-weathering suface layer,Eventually,the results also show that different species of lichens play different roles in weathering and soil-forming proesses.

  10. Large-amplitude gravity waves above the southern Andes, the Drake Passage, and the Antarctic Peninsula

    Science.gov (United States)

    de la Torre, A.; Alexander, P.; Hierro, R.; Llamedo, P.; Rolla, A.; Schmidt, T.; Wickert, J.

    2012-01-01

    Above the southern Andes range and its prolongation in the Antarctic Peninsula, large-amplitude mountain and shear gravity waves observed with Weather Research and Forecasting (WRF) mesoscale model simulations during winter 2009 are analyzed. Two specific reasons motivated this study: (1) a decade of satellite observations of temperature fluctuations in the stratosphere, allowing us to infer that this region may be launching the largest-amplitude gravity waves into the upper atmosphere, and (2) the recent design of a research program to investigate these features in detail, the Southern Andes Antarctic Gravity wave Initiative (SAANGRIA). The simulations are forced with ERA-Interim data from the European Centre for Medium-Range Weather Forecasts. The approach selected for the regional downscaling is based on consecutive integrations with weekly reinitialization with 24 h of spin-up, and the outputs during this period are excluded from the analysis. From 1 June to 31 August 2009, five case studies were selected on the basis of their outstanding characteristics and large wave amplitudes. In general, one or two prevailing modes of oscillation are identified after applying continuous wavelet transforms at constant pressure levels and perpendicularly to the nominal orientation of the dominant wave crests. In all cases, the dominant modes are characterized by horizontal wavelengths around 50 km. Their vertical wavelengths, depending on a usually strong background wind shear, are estimated to be between 2 and 11 km. The corresponding intrinsic periods range between 10 and 140 min. In general, the estimated vertical wavelength (intrinsic period) maximizes (minimizes) around 250-300 hPa. The synoptic circulation for each case is described. Zonal and meridional components of the vertical flux of horizontal momentum are shown in detail for each case, including possible horizontal wavelengths between 12 and 400 km. Large values of this flux are observed at higher pressure

  11. Circumpolar diversity and geographic differentiation of mtDNA in the critically endangered Antarctic blue whale (Balaenoptera musculus intermedia.

    Directory of Open Access Journals (Sweden)

    Angela L Sremba

    Full Text Available The Antarctic blue whale (Balaenoptera musculus intermedia was hunted to near extinction between 1904 and 1972, declining from an estimated initial abundance of more than 250,000 to fewer than 400. Here, we describe mtDNA control region diversity and geographic differentiation in the surviving population of the Antarctic blue whale, using 218 biopsy samples collected under the auspices of the International Whaling Commission (IWC during research cruises from 1990-2009. Microsatellite genotypes and mtDNA sequences identified 166 individuals among the 218 samples and documented movement of a small number of individuals, including a female that traveled at least 6,650 km or 131° longitude over four years. mtDNA sequences from the 166 individuals were aligned with published sequences from 17 additional individuals, resolving 52 unique haplotypes from a consensus length of 410 bp. From this minimum census, a rarefaction analysis predicted that only 72 haplotypes (95% CL, 64, 86 have survived in the contemporary population of Antarctic blue whales. However, haplotype diversity was relatively high (0.968±0.004, perhaps as a result of the longevity of blue whales and the relatively recent timing of the bottleneck. Despite the potential for circumpolar dispersal, we found significant differentiation in mtDNA diversity (F(ST = 0.032, p<0.005 and microsatellite alleles (F(ST = 0.005, p<0.05 among the six Antarctic Areas historically used by the IWC for management of blue whales.

  12. Circumpolar diversity and geographic differentiation of mtDNA in the critically endangered Antarctic blue whale (Balaenoptera musculus intermedia).

    Science.gov (United States)

    Sremba, Angela L; Hancock-Hanser, Brittany; Branch, Trevor A; LeDuc, Rick L; Baker, C Scott

    2012-01-01

    The Antarctic blue whale (Balaenoptera musculus intermedia) was hunted to near extinction between 1904 and 1972, declining from an estimated initial abundance of more than 250,000 to fewer than 400. Here, we describe mtDNA control region diversity and geographic differentiation in the surviving population of the Antarctic blue whale, using 218 biopsy samples collected under the auspices of the International Whaling Commission (IWC) during research cruises from 1990-2009. Microsatellite genotypes and mtDNA sequences identified 166 individuals among the 218 samples and documented movement of a small number of individuals, including a female that traveled at least 6,650 km or 131° longitude over four years. mtDNA sequences from the 166 individuals were aligned with published sequences from 17 additional individuals, resolving 52 unique haplotypes from a consensus length of 410 bp. From this minimum census, a rarefaction analysis predicted that only 72 haplotypes (95% CL, 64, 86) have survived in the contemporary population of Antarctic blue whales. However, haplotype diversity was relatively high (0.968±0.004), perhaps as a result of the longevity of blue whales and the relatively recent timing of the bottleneck. Despite the potential for circumpolar dispersal, we found significant differentiation in mtDNA diversity (F(ST) = 0.032, p<0.005) and microsatellite alleles (F(ST) = 0.005, p<0.05) among the six Antarctic Areas historically used by the IWC for management of blue whales. PMID:22412889

  13. Evaluating Wind Power Potential in the Spanish Antarctic Base (BAE)

    International Nuclear Information System (INIS)

    The objective of the work is to model wind field in the surroundings of the Spanish Antarctic Base (BAE in the following). The need of such a work comes from the necessity of an energy source able to supply the energy demand in the BAE during the Antarctic winter. When the BAE is in operation (in the Antarctic summer) the energy supply comes from a diesel engine. In the Antarctic winter the base is closed, but the demand of energy supply is growing up every year because of the increase in the number of technical and scientific machines that remain in the BAE taking different measurements. For this purpose the top of a closed hill called Pico Radio, not perturbed by close obstacles, has been chosen as the better site for the measurements. The measurement station is made up with a sonic anemometer and a small wind generator to supply the energy needed by the sensors head heating of the anemometer. This way, it will be also used as a proof for the suitability of a wind generator in the new chosen site, under those special climatic conditions.(Author) 3 refs

  14. Pioneering work of CAS researchers in Antarctic expedition

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ The first observatory at Dome A On 12 January, China scientific expedition to Antarctica succeeded for a second time in climbing up to Dome A, the highest Antarctic icecap peak. A similar feat was made by Chinese scientists about three years ago in January 2005, leaving first human footprints there.

  15. Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

    NARCIS (Netherlands)

    Rugenstein, M.; Stocchi, P.; van der Heydt, A.; Brinkhuis, H.

    2014-01-01

    During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale glaciation of Antarctica (~ 34 Myr) by combining solid Earth and ocean dynami

  16. Occurrence of a taurine derivative in an antarctic glass sponge.

    Science.gov (United States)

    Carbone, Marianna; Núñez-Pons, Laura; Ciavatta, M Letizia; Castelluccio, Francesco; Avila, Conxita; Gavagnin, Margherita

    2014-04-01

    The n-butanol extract of an Antarctic hexactinellid sponge, Anoxycalyx (Scolymastra) joubini, was found to contain a taurine-conjugated anthranilic acid, never reported so far either as a natural product or by synthesis. The compound was inactive against human cancer cells in an in vitro growth inhibitory test, and also showed no antibacterial activity. PMID:24868857

  17. Microbial ecology and biogeochemistry of continental Antarctic soils

    Directory of Open Access Journals (Sweden)

    Don A Cowan

    2014-04-01

    Full Text Available The Antarctica Dry Valleys are regarded as the coldest hyperarid desert system on Earth. While a wide variety of environmental stressors including very low minimum temperatures, frequent freeze-thaw cycles and low water availability impose severe limitations to life, suitable niches for abundant microbial colonization exist. Antarctic desert soils contain much higher levels of microbial diversity than previously thought. Edaphic niches, including cryptic and refuge habitats, microbial mats and permafrost soils all harbour microbial communities which drive key biogeochemical cycling processes. For example, lithobionts (hypoliths and endoliths possess a genetic capacity for nitrogen and carbon cycling, polymer degradation and other system processes. Nitrogen fixation rates of hypoliths, as assessed through acetylene reduction assays, suggest that these communities are a significant input source for nitrogen into these oligotrophic soils. Here we review aspects of microbial diversity in Antarctic soils with an emphasis on functionality and capacity. We assess current knowledge regarding adaptations to Antarctic soil environments and highlight the current threats to Antarctic desert soil communities.

  18. An Antarctic Circumpolar Current driven by surface buoyancy forcing

    Science.gov (United States)

    Hogg, Andrew McC.

    2010-12-01

    Simulations of an idealised, but eddy-resolving, channel model of the Antarctic Circumpolar Current (ACC) are used to investigate the sensitivity of ACC transport to wind and surface buoyancy forcing. The results are consistent with theoretical predictions of the eddy-saturated limit, where transport is independent of wind stress. In this parameter regime, buoyancy forcing provides the primary control over ACC transport.

  19. Molecular evolution of hemoglobins of Antarctic fishes (Notothenioidei)

    NARCIS (Netherlands)

    Stam, W.T.; Beintema, J.J; D Avino, R.; Tamburrini, M.; di Prisco, G.

    1997-01-01

    Amino acid sequences of alpha- and beta-chains of human hemoglobin and of hemoglobins of coelacanth and 24 teleost fish species, including 11 antarctic and two temperate Notothenioidei, were analyzed using maximum parsimony. Trees were derived for the alpha- and beta-chains separately and for tandem

  20. Maneuver simulation model of an experimental hovercraft for the Antarctic

    Science.gov (United States)

    Murao, Rinichi

    Results of an investigation of a hovercraft model designed for Antarctic conditions are presented. The buoyancy characteristics, the propellant control system, and simulation model control are examined. An ACV (air cushion vehicle) model of the hovercraft is used to examine the flexibility and friction of the skirt. Simulation results are presented which show the performance of the hovercraft.

  1. Antarctic Cenozoic climate history from sedimentary records: ANDRILL and beyond.

    Science.gov (United States)

    McKay, R M; Barrett, P J; Levy, R S; Naish, T R; Golledge, N R; Pyne, A

    2016-01-28

    Mounting evidence from models and geological data implies that the Antarctic Ice Sheet may behave in an unstable manner and retreat rapidly in response to a warming climate, which is a key factor motivating efforts to improve estimates of Antarctic ice volume contributions to future sea-level rise. Here, we review Antarctic cooling history since peak temperatures of the Middle Eocene Climatic Optimum (approx. 50 Ma) to provide a framework for future initiatives to recover sediment cores from subglacial lakes and sedimentary basins in Antarctica's continental interior. While the existing inventory of cores has yielded important insights into the biotic and climatic evolution of Antarctica, strata have numerous and often lengthy time breaks, providing a framework of 'snapshots' through time. Further cores, and more work on existing cores, are needed to reconcile Antarctic records with the more continuous 'far-field' records documenting the evolution of global ice volume and deep-sea temperature. To achieve this, we argue for an integrated portfolio of drilling and coring missions that encompasses existing methodologies using ship- and sea-ice-/ice-shelf-based drilling platforms as well as recently developed seafloor-based drilling and subglacial access systems. We conclude by reviewing key technological issues that will need to be overcome. PMID:26667911

  2. A novel Antarctic microbial endolithic community within gypsum crusts.

    Science.gov (United States)

    Hughes, Kevin A; Lawley, Blair

    2003-07-01

    A novel endolithic microbial habitat is described from a climatically extreme site at Two Step Cliffs, Alexander Island, Antarctic Peninsula (71 degrees 54'S, 68 degrees 13'W). Small endolithic colonies (endolithic communities are less extensive than those of the Dry Valleys, continental Antarctica, probably owing to only recent deglaciation (<7000 year ago). PMID:12823188

  3. Microbial ecology and biogeochemistry of continental Antarctic soils

    Science.gov (United States)

    Cowan, Don A.; Makhalanyane, Thulani P.; Dennis, Paul G.; Hopkins, David W.

    2014-01-01

    The Antarctica Dry Valleys are regarded as the coldest hyperarid desert system on Earth. While a wide variety of environmental stressors including very low minimum temperatures, frequent freeze-thaw cycles and low water availability impose severe limitations to life, suitable niches for abundant microbial colonization exist. Antarctic desert soils contain much higher levels of microbial diversity than previously thought. Edaphic niches, including cryptic and refuge habitats, microbial mats and permafrost soils all harbor microbial communities which drive key biogeochemical cycling processes. For example, lithobionts (hypoliths and endoliths) possess a genetic capacity for nitrogen and carbon cycling, polymer degradation, and other system processes. Nitrogen fixation rates of hypoliths, as assessed through acetylene reduction assays, suggest that these communities are a significant input source for nitrogen into these oligotrophic soils. Here we review aspects of microbial diversity in Antarctic soils with an emphasis on functionality and capacity. We assess current knowledge regarding adaptations to Antarctic soil environments and highlight the current threats to Antarctic desert soil communities. PMID:24782842

  4. Antarctic and Southern Ocean influences on Late Pliocene global cooling

    NARCIS (Netherlands)

    McKay, R.; Naish, T.; Carter, L.; Riesselman, C.; Dunbar, R.; Sjunneskog, C.; Winter, D.; Sangiorgi, F.; Warren, C.; Pagani, M.; Schouten, S.; Willmott, V.; Levy, R.; DeConto , R.M.; Powell, R.D.

    2012-01-01

    The influence of Antarctica and the Southern Ocean on Late Pliocene global climate reconstructions has remained ambiguous due to a lack of well-dated Antarctic-proximal, paleoenvironmental records. Here we present ice sheet, sea-surface temperature, and sea ice reconstructions from the ANDRILL AND-1

  5. Is there a distinct continental slope fauna in the Antarctic?

    Science.gov (United States)

    Kaiser, Stefanie; Griffiths, Huw J.; Barnes, David K. A.; Brandão, Simone N.; Brandt, Angelika; O'Brien, Philip E.

    2011-02-01

    The Antarctic continental slope spans the depths from the shelf break (usually between 500 and 1000 m) to ˜3000 m, is very steep, overlain by 'warm' (2-2.5 °C) Circumpolar Deep Water (CDW), and life there is poorly studied. This study investigates whether life on Antarctica's continental slope is essentially an extension of the shelf or the abyssal fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell Sea and Scotia Sea, including the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I-III, BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ (Ecology of the Antarctic Sea Ice Zone) II cruises as well as current databases (SOMBASE, SCAR-MarBIN), four different taxa were selected (i.e. cheilostome bryozoans, isopod and ostracod crustaceans and echinoid echinoderms) and two areas, the Weddell Sea and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations. Benthic samples were collected using Agassiz trawl, epibenthic sledge and Rauschert sled. By bathymetric definition, these data suggest that despite eurybathy in some of the groups examined and apparent similarity of physical conditions in the Antarctic, the shelf, slope and abyssal faunas were clearly separated in the Weddell Sea. However, no such separation of faunas was apparent in the Scotia Sea (except in echinoids). Using a geomorphological definition of the slope, shelf-slope-abyss similarity only changed significantly in the bryozoans. Our results did not support the presence of a homogenous and unique Antarctic slope fauna despite a high number of species being restricted to the slope. However, it remains the case that there may be

  6. Evaluation of the biological toxicity of lfuorine in Antarctic krill

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ling; LU Xiaoqi; WANG Zhangmin; QIN Liqiang; LIN Zhiqin; YUAN Linxi; ZHANG Wen; YIN Xuebin

    2014-01-01

    Antarctic krill is a potentially nutritious food source for humans, but lfuorine (F) toxicity is a matter of concern. To evaluate the toxicity of F in Antarctic krill, 30 Wistar rats were divided into three groups with different dietary regimens:a control group, a krill treatment group (150 mg·kg-1 F), and a sodium lfuoride (NaF) treatment group (150 mg·kg-1 F). After three months, F concentrations in feces, plasma, and bone were determined, and the degree of dental and skeletal lfuorosis was assessed. The F concentrations in plasma and bone from the krill treatment group were 0.167 0±0.020 4 mg.L-1 and 2 709.8±301.9 mg·kg-1, respectively, compared with 0.043 8±0.005 5 mg·L-1 and 442.4±60.7 mg·kg-1, respectively, in samples from the control group. Concentrations of F in plasma and bone in the krill treatment group were higher than in the control group, but lower than in the NaF treatment group. The degree of dental lfuorosis in the krill treatment group was moderate, compared with severe in the NaF treatment group and normal in the control group. The degree of skeletal lfuorosis did not change signiifcantly in any group. These results showed that the toxicity of F in Antarctic krill was lower than for an equivalent concentration of F in NaF, but it was toxic for rats consuming krill in large quantities. To conclude, we discuss possible reasons for the reduced toxicity of F in Antarctic krill. The present study provides a direct toxicological reference for the consideration of Antarctic krill for human consumption.

  7. A model study of the effect of climate and sea-level change on the evolution of the Antarctic Ice Sheet from the Last Glacial Maximum to 2100

    Science.gov (United States)

    Maris, M. N. A.; van Wessem, J. M.; van de Berg, W. J.; de Boer, B.; Oerlemans, J.

    2015-08-01

    Due to a scarcity of observations and its long memory of uncertain past climate, the Antarctic Ice Sheet remains a largely unknown factor in the prediction of global sea level change. As the history of the ice sheet plays a key role in its future evolution, in this study we model the Antarctic Ice Sheet from the Last Glacial Maximum (21 kyr ago) until the year 2100 with the ice-dynamical model ANICE. We force the model with different temperature, surface mass balance and sea-level records to investigate the importance of these different aspects for the evolution of the ice sheet. Additionally, we compare the model output from 21 kyr ago until the present with observations to assess model performance in simulating the total grounded ice volume and the evolution of different regions of the Antarctic Ice Sheet. Although there are some clear limitations of the model, we conclude that sea-level change has driven the deglaciation of the ice sheet, whereas future temperature change and the history of the ice sheet are the primary cause of changes in ice volume in the future. We estimate the change in grounded ice volume between its maximum (around 15 kyr ago) and the present-day to be between 8.4 and 12.5 m sea-level equivalent and the contribution of the Antarctic Ice Sheet to the global mean sea level in 2100, with respect to 2000, to be -22 to 63 mm.

  8. Influence of Ross Sea Bottom Water changes on the warming and freshening of the Antarctic Bottom Water in the Australian-Antarctic Basin

    Directory of Open Access Journals (Sweden)

    K. Shimada

    2012-07-01

    Full Text Available Changes to the properties of Antarctic Bottom Water in the Australian-Antarctic Basin (AA-AABW between the 1990s and 2000s are documented using data from the WOCE Hydrographic Program (WHP and repeated hydrographic surveys. Strong cooling and freshening are observed on isopycnal layers denser than γn = 28.30 kg m−3. Changes in the average salinity and potential temperature below this isopycnal correspond to a basin-wide warming of 1300 ± 200 GW and freshening of 24 ± 3 Gt year−1. Recent changes to dense shelf water in the source regions in the Ross Sea and George V Land can explain the freshening of AA-AABW but not its extensive warming. An alternative mechanism for this warming is a decrease in the supply of AABW from the Ross Sea (RSBW. Hydrographic profiles between the western Ross Sea and George V Land (171–158° E were analyzed with a simple advective-diffusive model to assess the causes of the observed changes. The model suggests that the warming of RSBW observed between the 1970s and 2000s can be explained by a 21 ± 23% reduction in RSBW transport and the enhancement of the vertical diffusion of heat resulting from a 30 ± 7% weakening of the abyssal stratification. The documented freshening of Ross Sea dense shelf water leads to a reduction in both salinity and density stratification. Therefore the direct freshening of RSBW at its source also produces an indirect warming of the RSBW. A simple box model suggests that the changes in RSBW properties and volume transport (a decrease of 6.7% is assumed between the year 1995 and 2005 can explain 51 ± 6% of the warming and 84 ± 10% of the freshening observed in AA-AABW.

  9. At-Sea Distribution and Prey Selection of Antarctic Petrels and Commercial Krill Fisheries.

    Science.gov (United States)

    Descamps, Sébastien; Tarroux, Arnaud; Cherel, Yves; Delord, Karine; Godø, Olaf Rune; Kato, Akiko; Krafft, Bjørn A; Lorentsen, Svein-Håkon; Ropert-Coudert, Yan; Skaret, Georg; Varpe, Øystein

    2016-01-01

    Commercial fisheries may impact marine ecosystems and affect populations of predators like seabirds. In the Southern Ocean, there is an extensive fishery for Antarctic krill Euphausia superba that is projected to increase further. Comparing distribution and prey selection of fishing operations versus predators is needed to predict fishery-related impacts on krill-dependent predators. In this context, it is important to consider not only predators breeding near the fishing grounds but also the ones breeding far away and that disperse during the non-breeding season where they may interact with fisheries. In this study, we first quantified the overlap between the distribution of the Antarctic krill fisheries and the distribution of a krill dependent seabird, the Antarctic petrel Thalassoica antarctica, during both the breeding and non-breeding season. We tracked birds from the world biggest Antarctic petrel colony (Svarthamaren, Dronning Maud Land), located >1000 km from the main fishing areas, during three consecutive seasons. The overall spatial overlap between krill fisheries and Antarctic petrels was limited but varied greatly among and within years, and was high in some periods during the non-breeding season. In a second step, we described the length frequency distribution of Antarctic krill consumed by Antarctic petrels, and compared this with results from fisheries, as well as from diet studies in other krill predators. Krill taken by Antarctic petrels did not differ in size from that taken by trawls or from krill taken by most Antarctic krill predators. Selectivity for specific Antarctic krill stages seems generally low in Antarctic predators. Overall, our results show that competition between Antarctic petrels and krill fisheries is currently likely negligible. However, if krill fisheries are to increase in the future, competition with the Antarctic petrel may occur, even with birds breeding thousands of kilometers away. PMID:27533327

  10. At-Sea Distribution and Prey Selection of Antarctic Petrels and Commercial Krill Fisheries

    Science.gov (United States)

    Descamps, Sébastien; Tarroux, Arnaud; Cherel, Yves; Delord, Karine; Godø, Olaf Rune; Kato, Akiko; Krafft, Bjørn A.; Lorentsen, Svein-Håkon; Ropert-Coudert, Yan; Skaret, Georg; Varpe, Øystein

    2016-01-01

    Commercial fisheries may impact marine ecosystems and affect populations of predators like seabirds. In the Southern Ocean, there is an extensive fishery for Antarctic krill Euphausia superba that is projected to increase further. Comparing distribution and prey selection of fishing operations versus predators is needed to predict fishery-related impacts on krill-dependent predators. In this context, it is important to consider not only predators breeding near the fishing grounds but also the ones breeding far away and that disperse during the non-breeding season where they may interact with fisheries. In this study, we first quantified the overlap between the distribution of the Antarctic krill fisheries and the distribution of a krill dependent seabird, the Antarctic petrel Thalassoica antarctica, during both the breeding and non-breeding season. We tracked birds from the world biggest Antarctic petrel colony (Svarthamaren, Dronning Maud Land), located >1000 km from the main fishing areas, during three consecutive seasons. The overall spatial overlap between krill fisheries and Antarctic petrels was limited but varied greatly among and within years, and was high in some periods during the non-breeding season. In a second step, we described the length frequency distribution of Antarctic krill consumed by Antarctic petrels, and compared this with results from fisheries, as well as from diet studies in other krill predators. Krill taken by Antarctic petrels did not differ in size from that taken by trawls or from krill taken by most Antarctic krill predators. Selectivity for specific Antarctic krill stages seems generally low in Antarctic predators. Overall, our results show that competition between Antarctic petrels and krill fisheries is currently likely negligible. However, if krill fisheries are to increase in the future, competition with the Antarctic petrel may occur, even with birds breeding thousands of kilometers away. PMID:27533327

  11. A decade of progress in observing and modelling Antarctic subglacial water systems.

    Science.gov (United States)

    Fricker, Helen A; Siegfried, Matthew R; Carter, Sasha P; Scambos, Ted A

    2016-01-28

    In the decade since the discovery of active Antarctic subglacial water systems by detection of subtle surface displacements, much progress has been made in our understanding of these dynamic systems. Here, we present some of the key results of observations derived from ICESat laser altimetry, CryoSat-2 radar altimetry, Operation IceBridge airborne laser altimetry, satellite image differencing and ground-based continuous Global Positioning System (GPS) experiments deployed in hydrologically active regions. These observations provide us with an increased understanding of various lake systems in Antarctica: Whillans/Mercer Ice Streams, Crane Glacier, Recovery Ice Stream, Byrd Glacier and eastern Wilkes Land. In several cases, subglacial water systems are shown to control ice flux through the glacier system. For some lake systems, we have been able to construct more than a decade of continuous lake activity, revealing internal variability on time scales ranging from days to years. This variability indicates that continuous, accurate time series of altimetry data are critical to understanding these systems. On Whillans Ice Stream, our results from a 5-year continuous GPS record demonstrate that subglacial lake flood events significantly change the regional ice dynamics. We also show how models for subglacial water flow have evolved since the availability of observations of lake volume change, from regional-scale models of water routeing to process models of channels carved into the subglacial sediment instead of the overlying ice. We show that progress in understanding the processes governing lake drainage now allows us to create simulated lake volume time series that reproduce time series from satellite observations. This transformational decade in Antarctic subglacial water research has moved us significantly closer to understanding the processes of water transfer sufficiently for inclusion in continental-scale ice-sheet models. PMID:26667904

  12. In-situ aircraft observations of ice concentrations within clouds over the Antarctic Peninsula and Larsen Ice Shelf

    Directory of Open Access Journals (Sweden)

    D. P. Grosvenor

    2012-12-01

    Full Text Available In-situ aircraft observations of ice crystal concentrations in Antarctic clouds are presented for the first time. Orographic, layer and wave clouds around the Antarctic Peninsula and Larsen Ice shelf regions were penetrated by the British Antarctic Survey's Twin Otter aircraft, which was equipped with modern cloud physics probes. The clouds studied were mostly in the free troposphere and hence ice crystals blown from the surface are unlikely to have been a major source for the ice phase. The temperature range covered by the experiments was 0 to −21 °C. The clouds were found to contain supercooled liquid water in most regions and at heterogeneous ice formation temperatures ice crystal concentrations (60 s averages were often less than 0.07 l−1, although values up to 0.22 l−1 were observed. Estimates of observed aerosol concentrations were used as input into the DeMott et al. (2010 ice nuclei (IN parameterisation. The observed ice crystal number concentrations were generally in broad agreement with the IN predictions, although on the whole the predicted values were higher. Possible reasons for this are discussed and include the lack of IN observations in this region with which to characterise the parameterisation, and/or problems in relating ice concentration measurements to IN concentrations. Other IN parameterisations significantly overestimated the number of ice particles. Generally ice particle concentrations were much lower than found in clouds in middle latitudes for a given temperature.

    Higher ice crystal concentrations were sometimes observed at temperatures warmer than −9 °C, with values of several per litre reached. These were attributable to secondary ice particle production by the Hallett Mossop process. Even in this temperature range it was observed that there were regions with little or no ice that were dominated by supercooled liquid water. It is likely that in some cases this was due to a

  13. Unmanned aerial optical systems for spatial monitoring of Antarctic mosses

    Science.gov (United States)

    Lucieer, Arko; Turner, Darren; Veness, Tony; Malenovsky, Zbynek; Harwin, Stephen; Wallace, Luke; Kelcey, Josh; Robinson, Sharon

    2013-04-01

    The Antarctic continent has experienced major changes in temperature, wind speed and stratospheric ozone levels during the last 50 years. In a manner similar to tree rings, old growth shoots of Antarctic mosses, the only plants on the continent, also preserve a climate record of their surrounding environment. This makes them an ideal bio-indicator of the Antarctic climate change. Spatially extensive ground sampling of mosses is laborious and time limited due to the short Antarctic growing season. Obviously, there is a need for an efficient method to monitor spatially climate change induced stress of the Antarctic moss flora. Cloudy weather and high spatial fragmentation of the moss turfs makes satellite imagery unsuitable for this task. Unmanned aerial systems (UAS), flying at low altitudes and collecting image data even under a full overcast, can, however, overcome the insufficiency of satellite remote sensing. We, therefore, developed scientific UAS, consisting of a remote-controlled micro-copter carrying on-board different remote sensing optical sensors, tailored to perform fast and cost-effective mapping of Antarctic flora at ultra-high spatial resolution (1-10 cm depending on flight altitude). A single lens reflex (SLR) camera carried by UAS acquires multi-view aerial photography, which processed by the Structure from Motion computer vision algorithm provides an accurate three-dimensional digital surface model (DSM) at ultra-high spatial resolution. DSM is the key input parameter for modelling a local seasonal snowmelt run-off, which provides mosses with the vital water supply. A lightweight multispectral camera on-board of UVS is collecting images of six selected spectral wavebands with the full-width-half-maximum (FWHM) of 10 nm. The spectral bands can be used to compute various vegetation optical indices, e.g. Difference Vegetation Index (NDVI) or Photochemical Reflectance Index (PRI), assessing the actual physiological state of polar vegetation. Recently

  14. Circulation of Antarctic intermediate water in the South Indian Ocean

    Science.gov (United States)

    Fine, Rana A.

    1993-10-01

    Chlorofluorocarbon (CFC) and hydrographic data collected on the R.R.S. Charles Darwin Cruise 29 along 32°S during November-December 1987, are used to examine the circulation in the South Indian Ocean. The emphasis is on Antarctic Intermediate Water (AAIW); bottom waters and mode waters are also examined. Bottom waters entering in the western boundary of the Crozet Basin (about 60°E) and in the Mozambique Basin (about 40°E) have low concentrations of anthropogenic CFCs. The rest of the bottom and deep waters up to about 2000 m have concentrations that are below blank levels. Above the intermediate waters there are injections of mode waters, which are progressively denser in the eastward direction. They form a broad subsurface CFC maximum between 200 and 400 m. The injections of recently ventilated (with respect to CFCs and oxygen) Subantarctic Mode Waters (SAMWs) at different densities indicate that there is considerable exchange between the subtropical and subantarctic regions. The tracer data presented show that the circulation of AAIW in the South Indian Ocean is different from that in the South Atlantic and South Pacific oceans in several ways. (1) The most recently ventilated AAIW is observed in a compact anticyclonic gyre west of 72°E. The shallow topography (e.g. that extending northeastward from the Kerguelen Plateau) may deflect and limit the eastward extent of the most recently ventilated AAIW. As a consequence, there is a zonal offset in the South Indian Ocean of the location of the most recently ventilated SAMW and AAIW, which does not occur in the other two oceans. The strongest component of SAMW is in the east, while the AAIW is strongest in the western-central South Indian Ocean. The offset results in a higher vertical gradient in CFCs in the east. (2) The Agulhas Current may impede input of AAIW along the western boundary. (3) Tracers are consistent with an inter-ocean flow from the South Pacific into the Eastern Indian Ocean, similar to the

  15. Interpretation of ground and aeromagnetic surveys of Palmer Land, Antarctic Peninsula

    Directory of Open Access Journals (Sweden)

    V. N. Masolov

    2000-06-01

    Full Text Available Aeromagnetic data for Palmer Land provide new information on crustal structures of the Antarctic Peninsula. Features shown on the compilation of the Lassiter Coast and Orville Coast are characterized by systems of subparallel regional anomaly zones and lineaments. The magnetic data reveal the widespread presence of an orthogonal pattern of crosscutting linear discontinuities that can be interpreted as a Late Cretaceous/Early Tertiary fracture pattern. The main displacements in the anomaly pattern between the two units are recognized in Wetmore-Irvine glaciers area where the structure of the Antarctic Peninsula changes orientation from SW-NE to S-N. The NW-SE trending transitional zone is probably a transfer zone associated with north-westerly movement of the Lassiter Coast crustal segment relative to the Orville Coast segment. Within the Lassiter Coast a fragment of Pacific Margin Anomaly (PMA, Central Plateau Magnetic Anomaly and East Coast Magnetic Anomaly (ECMA are mapped. Two-dimensional modelling suggests that PMA is caused by a limited depth body (8 km consisting of numerous plutons, probably, of different ages, composition and magnetization. The Central Plateau Magnetic Anomaly and the Merrick-Sweeney-Latady zone of the Orville Coast are represented by strong positive anomaly bands that are associated with gabbro-diorite rocks and accompanying plutons intruded near by the border of Mount Poster Formation and Latady Formation. The ECMA are alignments of high-amplitude magnetic anomalies caused by gabbro-diorite bodies, which are located within the framework of the Cretaceous granite-granodiorite plutons. Granite-granodiorite plutons of Lassiter Coast Intrusive Suite are mostly reflected by positive anomalies (100-500 nT. Modelling studies and the character of distribution of the magnetic anomalies suggest that the plutons of Lassiter Coast Intrusive Suite are prominently reflected in magnetic anomalies of regional extent. The plutonic

  16. A Late Miocene-Pliocene Antarctic Deepwater Record of Cyclic Iron Reduction Events (ODP Leg 178 Site 1095)

    Science.gov (United States)

    Hepp, D. A.; Moerz, T.

    2007-12-01

    The Pacific margin off the Antarctic Peninsula is very sensitive to climate and ice-sheet volume changes. Climatic variations on the continental shelf control regional sedimentary processes and foster the build-up of giant deep- sea sediment drifts. These drifts represent the most proximal continuous sedimentary recorders for West Antarctic ice sheet evolution and glacial-interglacial cyclicity pattern. Sediment physical, geochemical records and x-ray images derived from ODP Site 1095 (Drift 7) were used to identify pattern in glacial-interglacial cyclicity and associated sedimentary and diagenetic processes during late Miocene and Pliocene. Two boundary types dividing half-cycles have been recognized: (1) interglacial-to-glacial transitions are characterized by a sharp boundary and abrupt change in lithology; (2) glacial-to-interglacial transitions can described as a gradual change from a full glacial to a full interglacial stage. A prominent feature of the glacial-to-interglacial transition is the loss of the magnetic susceptibility signal, caused by diagenetic alteration and demagnetization of magnetic iron minerals in a suboxic to anoxic sediment environment. Similar redox processes are described for organic carbon rich Madeira abyssal plain turbidites and Mediterranean sapropels, but are uncommon for vented Circum- Antarctic deep-sea sediments. Iron reduction zones were coupled to the ice sheet collapse at the end of deglaciation phases. Ice sheet collapse and meltwater formation weaken the bottom water formation and convection, but foster short living diatom blooms resulting in high fluxes of organic matter to the seafloor. Iron reduction zones were observed in sixty-four zones of ODP Site 1095 cores. Thus, the sedimentary record of Drift 7 affords an unique opportunity to study cyclic iron reduction events at long time-scales. The occurrence and intensity of those 'diagenetic zones' reflect long-term trends of global climate change and the related

  17. Relationship between the Antarctic oscillation in the western North Pacific typhoon frequency

    Institute of Scientific and Technical Information of China (English)

    WANG HuiJun; FAN Ke

    2007-01-01

    Relationship between the Antarctic oscillation (AAO) and the western North Pacific typhoon number (WNPTN) in the interannual variability is examined in this research. The WNPTN is correlated with the AAO in June-July-August-September (JJAS) in 1949-1998 at -0.48 for the detrended time series, statistically significant at 99% level. The tropical atmospheric circulation as well as the sea surface temperature variability over the western Pacific associated with AAO has been analyzed. It follows that a positive phase of JJAS AAO corresponds to the larger magnitude of the vertical zonal wind shear, the anomalous low-lever anti-cyclonic circulation and anomalous high-level cyclonic circulation, and lower sea surface temperature in the major typhoon genesis region in the western North Pacific, thus providing unfavorable environment for the typhoon genesis, and vice versa.

  18. Rapid bedrock uplift in the Antarctic Peninsula explained by viscoelastic response to recent ice unloading

    DEFF Research Database (Denmark)

    Nield, Grace A.; Barletta, Valentina Roberta; Bordoni, Andrea;

    2014-01-01

    ×1017–2×1018 Pas – much lower than previously suggested for this region. Combining the LARISSA time series with the Palmer cGPS time series offers a rare opportunity to study the time-evolution of the low-viscosity solid Earth response to a well-captured ice unloading event.......Since 1995 several ice shelves in the Northern Antarctic Peninsula have collapsed and triggered ice-mass unloading, invoking a solid Earth response that has been recorded at continuous GPS (cGPS) stations. A previous attempt to model the observation of rapid uplift following the 2002 breakup...... of the Palmer cGPS station since 2002 cannot be explained by elastic deformation alone. We apply a viscoelastic model with linear Maxwell rheology to predict uplift since 1995 and test the fit to the Palmer cGPS time series, finding a well constrained upper mantle viscosity but less sensitivity to lithospheric...

  19. Snow chemistry measurements on James Ross Island (Antarctic Peninsula) showing sea-salt aerosol modifications

    Energy Technology Data Exchange (ETDEWEB)

    Aristarain, A.J. [Instituto Antartico Argentino (Argentina). Lab. de Estratigrafia Glaciar y Geoquimica de la Nieve; Consejo Nacional de Investigaciones Cientificas y Tecnicas, Mendoza (Argentina); Delmas, R.J. [Laboratoire de Glaciologie et Geophysique de l' Environnement du CNRS, St Martin d' Heres (France)

    2002-07-01

    The fractionation of atmospheric sea-salt has been investigated by glaciochemical analysis of the sea-salt deposited on the snow covering the small ice cap of James Ross Island, Antarctic Peninsula, at an elevation of 1640m. The data show that, generally, but not always, the sea-salt deposited at this location most likely originates directly from seawater, as is the case at lower latitudes. It is found that the original chemical composition of the sea-salt aerosol is significantly modified, in particular by the reaction of sea-salt particles in the atmosphere with acid species. A ternary diagram (sodium, chloride, sulfate) is used to enlighten the involved modification processes. The study points out the frequent formation of HCl in the regional atmosphere. (Author)

  20. Antarctic ice sheet GLIMMER model test and its simplified model on 2-dimensional ice flow

    Institute of Scientific and Technical Information of China (English)

    Xueyuan Tang; Zhanhai Zhang; Bo Sun; Yuansheng Li; Na Li; Bangbing Wang; Xiangpei Zhang

    2008-01-01

    The 3-dimensional finite difference thermodynamic coupled model on Antarctic ice sheet, GLIMMER model, is described. An ide-alized ice sheet numerical test was conducted under the EISMINT-I benchmark, and the characteristic curves of ice sheets under steady state were obtained. Based on this, this model was simplified from a 3-dimensional one to 2-dimensional one. Improvement of the dif-ference method and coordinate system was proposed. Evolution of the 2-dimensional ice flow was simulated under coupled temperature field conditions. The results showed that the characteristic curves deriving from the conservation of the mass, momentum and energy agree with the results of ice sheet profile simulated with GLIMMER model and with the theoretical results. The application prospect of the simplified 2-dimensional ice flow model to simulate the relation of age-depth-accumulation in Dome A region was discussed.

  1. 'Unlocking the archive': Using digital photogrammetry of modern and historic aerial photography to reconstruct 60 years of volumetric change on the Moider Glacier, Antarctic Peninsula

    Science.gov (United States)

    Clarke, Lucy; Miller, Pauline; Ireland, Louise; Fox, Adrian; Mills, Jon; Fieber, Karolina

    2016-04-01

    The Antarctic Peninsula is a mountain glacier system comprised of over 400 glaciers, and is an important contributor to historical and future sea level rise. Assessment and monitoring of AP glaciers is crucial for understanding sensitivity to climate change. Changes to glacier fronts and ice shelves and glacier acceleration are well documented, but there are almost no data on mass changes on the Antarctic Peninsula. Satellite data have been used to calculate change over the last 3 decades, but methods to quantify this over longer timescales have eluded researchers. However there is an archive of aerial photography dating back to the 1940s, this has been largely ignored due to the range of technical problems associated with deriving quantitative data from historic imagery and the lack of ground control data. This presentation demonstrates how advances in photogrammetric processing and capture of modern aerial photography has allowed this archive to be 'unlocked'. Accurate photogrammetric reconstruction from aerial photographs traditionally requires known ground control points acquired in the field; in remote and inaccessible areas, such as the Antarctic Peninsula, this is often impossible. A method for providing control for historic photos without fieldwork, by linking them to a newly acquired, highly accurate photogrammetric model adjusted through direct kinematic GPS positioning of the camera has been applied to a number of glaciers across the Antarctic Peninsula. This presentation will outline the photogrammetric workflow with focus on the Moider Glacier in the Marguerite Bay region of the western Antarctic Peninsula to investigate the quality of data that can be obtained. Volumetric changes on the glaciers from the 1950s to present day (2015) have been reconstructed and can be used to explore the spatial and temporal changes that have occurred on this glacier. In particular, there is near-annual data over the last 5 years recording a period when there has been

  2. 南极臭氧洞的发现、研究和启示%The Antarctic Ozone Hole and its Discovery, Research and Inspiration

    Institute of Scientific and Technical Information of China (English)

    陆龙骅

    2016-01-01

    回顾了南极臭氧洞的发现过程,评述了南极臭氧洞形成和发展的机制、以及南北极臭氧变化的差异,讨论了南极臭氧洞的发现和研究带来的启示。研究指出,目前只是在南极春季出现了臭氧洞,北极并没有出现过臭氧洞。在当前大气环境被污染的情况下,极地大气臭氧亏损的程度将更多地随大气环流,特别是极地涡旋中的低温状况而发生变化。%This study reviews the detection and the variety of the Antarctic ozone hole; the reason why the ozone hole is formed over the Antarctic is discussed, while the different patterns of the ozone variation over the Arctic and the Antarctic are outlined. It is also discussed the inspiration obtained throughout the detection and research of Antarctic ozone hole. It is pointed out that, currently, the ozone hole appears only in spring over the Antarctic and not appeared yet over the Arctic. Under the current atmospheric environment with the added pollution, the change of atmospheric ozone depletion over the Polar Regions will be more dependent on the atmospheric circulation, especially the low temperature in the polar vortex.

  3. Oligocene environmental changes on the Wilkes Land margin in response to a developing East Antarctic ice sheet

    OpenAIRE

    Houben, A. J. P.; Bijl, P.K; Brinkhuis, H.; Bendle, J.A.; J. Pross; Stickley, C.E.; Olney, M.; Röhl, U.; Tauxe, L.; S. M. Bohaty; Schouten, S.; Ebbing, A.P.J.; Sangiorgi, F.; Stocchi, P.; Vermeersen, B.

    2011-01-01

    IODP Expedition 318 drilled several sites on the Wilkes Land margin of East Antarctica in Jan.–Feb. 2010. The principle objective of the cruise was to obtain a better understanding of the Cenozoic cryospheric evolution of Antarctica, in conjunction with the dating of major regional seismic unconformities WL-U3 thru U8. Unconformity WL-U3 was suggested to be related to the inception of Antarctic glaciation during the Eocene-Oligocene Transition (~34 Ma). Changes in biotic assemblages distinctl...

  4. Diversity in deep-sea benthic macrofauna: the importance of local ecology, the larger scale, history and the Antarctic

    Science.gov (United States)

    Gage, John D.

    2004-07-01

    High diversity in macrobenthos in the deep sea still lacks satisfactory explanation, even if this richness may not be exceptional compared to that in coastal soft sediments. Explanations have assumed a highly ecologically interactive, saturated local community with co-existence controlled by either niche heterogeneity, or spatio-temporal heterogeneity embodying disturbance. All have failed to provide convincing support. Local/regional scale biodiversity relationships support the idea of local richness in macrobenthos being predominantly dependent on the larger, rather local scale. Local-scale ecological interactions seem unlikely to have overriding importance in co-existence of species in the deep sea, even for relatively abundant, 'core' species with wide distributions. Variety in observed larger-scale pattern and the strong inter-regional pattern, particularly in the poorly known southern hemisphere, seem to have a pluralistic causation. These include regional-scale barriers and extinctions (e.g., Arctic), and ongoing adaptive zone re-colonisation (e.g., Mediterranean), along with other historical constraints on speciation and migration of species caused by changes in ocean and ocean-basin geometry. At the global scale lack of knowledge of the Antarctic deep sea, for example, blocks coherent understanding of latitudinal species diversity gradients. We need to reconcile emerging understanding of large-scale historical variability in the deep-sea environment—with massive extinctions among microfossil indicators as recently as the Pliocene—to results from cladistic studies indicating ancient lineages, such as asellote isopods, that have evolved entirely within the deep sea. The degree to which the great age, diversity, and high degree of endemism in Antarctic shelf benthos might have enriched biodiversity in the adjacent deep seas basins remains unclear. Basin confluence with the Atlantic, Indian and Pacific Oceans may have encouraged northwards dispersion of

  5. The transantarctic mountains: A natural laboratory for apatite fission-track analysis. Results from Italian antarctic expeditions

    International Nuclear Information System (INIS)

    Apatite fission-track analysis has been applied to samples collected during the 1991/1992, 1993/1994 and 1996/1997 campaigns of the Italian Antarctic Project in the Transantarctic Mountains. Samples from the first two campaigns, collected in the area between the Mariner and the David Glaciers (northern Victoria Land), reveal that a Late Cretaceous uplift - denudation phase already identified in other sectors of the chain took place also in this region. They also confirm the occurrence of a more recent phase starting in the Late Paleocene. Offsets in apatite age profiles regarding samples collected further north during the third campaign reveal Cenozoic normal faulting with variable sense of offset

  6. Exposure-age record of Holocene ice sheet and ice shelf change in the northeast Antarctic Peninsula

    OpenAIRE

    Balco, G.; Schaefer, J. M.; LARISSA group

    2013-01-01

    This paper describes glacial–geologic observations and cosmogenic-nuclide exposure ages from ice-free areas adjacent to the Sjögren, Boydell, and Drygalski Glaciers of the northeast Antarctic Peninsula. These provide a record of Holocene glacier and ice shelf change in this region. Early Holocene ice surface elevation near the present coastline was locally at least 500 m above present sea level, but our observations do not constrain the maximum thickness of Last Glacial Maximum (LGM) ice or t...

  7. Relative Changes in KrillAbundance Inferred from Antarctic Fur Seal

    OpenAIRE

    Huang, T.; Sun, L; Stark, John M.; Wang, Y.; Cheng, Z.; Yang, Q.; Sun, S.

    2011-01-01

    Antarctic krill Euphausia superba is a predominant species in the Southern Ocean, it is very sensitive to climate change, and it supports large stocks of fishes, seabirds, seals and whales in Antarctic marine ecosystems. Modern krill stocks have been estimated directly by net hauls and acoustic surveys; the historical krill density especially the long-term one in the Southern Ocean, however, is unknown. Here we inferred the relative krill population changes along the West Antarctic Peninsula ...

  8. Mitochondrial plasticity in response to changing abiotic factors in Antarctic fish and cephalopods

    OpenAIRE

    Strobel, Anneli

    2013-01-01

    Antarctic species possess very low metabolic rates and poor capacities to change their physiological state, thus making them extremely vulnerable to changing environmental conditions. Mitochondria are a key element in shaping whole organism energy turnover and functional capacity. In my study, the effects of rising temperature and increased seawater PCO2 on the energy metabolism were compared between various nototheniids from sub-Antarctic and cold-temperate and Antarctic waters, and between ...

  9. Origin of the Adventure Subglacial Trench linked to Cenozoic extension in the East Antarctic Craton

    Science.gov (United States)

    Cianfarra, P.; Salvini, F.

    2016-02-01

    The Antarctic plate occupies a unique geodynamic setting being mostly surrounded by divergent or transform margins. Major intracontinental basins and highlands characterize its bedrock, buried under the 34 Ma East Antarctic Ice Sheet (EAIS). Their formation atop of the cratonic lithosphere in the interior of East Antarctica remains a major open question. Post-Mesozoic intraplate extensional tectonic activity has been proposed for their development and is supported by this work. Here we focus on the Adventure Subglacial Trench (AST) whose origin is poorly constrained and controversial, as currently available geophysical models suggest either extensional or compressional tectonic origin. The AST is an over 250-km-long, 60-km-wide subglacial trough, elongated in the NNW-SSE direction adjacent to the westernmost flank of the Wilkes Subglacial Basin, and is parallel to regional scale alignments of magnetic and gravimetric anomalies. Geophysical campaigns allowed better definition of the AST physiography showing its typical half-graben geometry. The rounded morphology of the western flank of the AST was simulated through tectonic numerical modelling. We consider the subglacial landscape to primarily reflect a preserved relict of the tectonic processes affecting the interior of East Antarctica in the Cenozoic, due to the negligible erosion/deposition capability of the EAIS. The bedrock morphology was replicated through the activity of the listric Adventure Fault, characterized by a basal detachment at the base of the crust (34 km) and a vertical displacement of 2.5 km. This length suggests its regional/crustal importance. The predicted displacement is interpreted either as a newly formed fault or as the partial reactivation of a weaker zone along a major Precambrian crustal-scale tectonic boundary. The extensional regime in the AST is part of a more extensive 800-km long intraplate corridor characterized by nearly along-strike extension in Cenozoic times with a left

  10. Levoglucosan indicates high levels of biomass burning aerosols over oceans from the Arctic to Antarctic

    Science.gov (United States)

    Hu, Q.; Xie, Z.; Wang, X.; Kang, H.; Zhang, P.

    2015-12-01

    Biomass burning discharges numerous kinds of gases and aerosols, such as carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), black carbon (BC), alcohols, organic acids and persistent organic pollutants (POPs), and is known to affect air quality, global carbon cycle, and climate. However, the extent to which biomass burning gases/aerosols are present on a global scale, especially in the marine atmosphere, is poorly understood. Here we measure levoglucosan, a superior molecular tracer of biomass burning aerosols because of its single source, in marine air from the Arctic Ocean through the North and South Pacific Ocean to coastal Antarctica during burning season. Levoglucosan was found to be present in all regions at ng/m3 levels. As a whole, levoglucosan concentrations in the Southern Hemisphere were comparable to those in the Northern Hemisphere. Marine air in the mid-latitudes (30°-60° N and S) has the highest levoglucosan loading due to the emission from adjacent lands. Air over the Arctic Ocean which affected by biomass burning in the east Siberia has intermediate loading. Equatorial latitudes is the main source of biomass burning emissions, however, levoglucosan is in relatively low level. Large amount of precipitation and high hydroxyl radical concentration in this region cause more deposition and degradation of levoglucosan during transport. Previous studies were debatable on the influence of biomass burning on the Antarctic because of uncertain source of BC. Here via levoglucosan, it is proved that although far away from emission sources, the Antarctic is still affected by biomass burning aerosols which may be derived from South America. Biomass burning has a significant impact on mercury (Hg) and water-soluble organic carbon (WSOC) in marine aerosols from pole to pole, with more contribution to WSOC in the Northern Hemisphere than in the Southern Hemisphere.

  11. On the manoeuvering simulation of an Antarctic hovercraft

    Science.gov (United States)

    Murao, R.; Nojiri, T.

    Since 1981 an experimental hovercraft for the Antarctic has been tested in Japan's Antarctic station Syowa. During tests on the ice field near Syowa station, it was experienced that the yaw response of this craft is very sensitive to certain ice conditions. In this report, we deal with course keeping of the craft in relative crosswinds and with the maneuvering simulation while turning. Maneuvering at large yaw angle is required to generate the effective centripetal force in turning. The trajectories based on pulse steering are obtained. The course stability is very dependent upon the friction between skirts and ground, and generally not good on smooth flat ice. It is shown, however, that the rudder automatic control provides good course stability independent of ice conditions. The trajectories obtained from the simulation show that the use of a combination of rudder control and puff ports produces quick turning.

  12. The 1988 Antarctic ozone depletion - Comparison with previous year depletions

    Science.gov (United States)

    Schoeberl, Mark R.; Stolarski, Richard S.; Krueger, Arlin J.

    1989-01-01

    The 1988 spring Antarctic ozone depletion was observed by TOMS to be substantially smaller than in recent years. The minimum polar total ozone values declined only 15 percent during September 1988, compared to nearly 50 percent during September 1987. At southern midlatitudes, exceptionally high total ozone values were recorded beginning in July 1988. The total integrated southern hemispheric ozone increased rapidly during the Austral spring, approaching 1980 levels during October. The high midlatitude total ozone values were associated with a substantial increase in eddy activity as indicated by the standard deviation in total ozone in the zonal band 30-60 deg S. Mechanisms through which the increased midlatitude eddy activity could disrupt the formation of the Antarctic ozone hole are briefly discussed.

  13. Ozone depletion - Ultraviolet radiation and phytoplankton biology in Antarctic waters

    Science.gov (United States)

    Smith, R. C.; Prezelin, B. B.; Baker, K. S.; Bidigare, R. R.; Boucher, N. P.; Coley, T.; Karentz, D.; Macintyre, S.; Matlick, H. A.; Menzies, D.

    1992-01-01

    The near-50-percent thinning of the stratospheric ozone layer over the Antarctic, with increased passage of mid-UV radiation to the surface of the Southern Ocean, has prompted concern over possible radiation damage to the near-surface phytoplankton communities that are the bases of Antarctic marine ecosystems. As the ozone layer thinned, a 6-week study of the marginal ice zone of the Bellingshousen Sea in the austral spring of 1990 noted sea-surface and depth-dependent ratios of mid-UV irradiance to total irradiance increased, and mid-UV inhibition of photosynthesis increased. A 6-12 percent reduction in primary production associated with ozone depletion was estimated to have occurred over the course of the present study.

  14. Antarctic springtime ozone depletion computed from temperature observations

    Science.gov (United States)

    Rosenfield, Joan E.; Schoeberl, Mark R.; Newman, Paul A.

    1988-01-01

    An observationally based, mechanistic dynamical model is used to simulate the decline of total ozone during September and October for the years 1979 through 1986. Vertical velocities derived from observed stratospheric temperature changes and computed radiative heating rates are used to advect an ozone mixing ratio profile during the Antarctic spring period. An early August 1982 Syowa balloonsonde ozone profile is used to initialize the computations. The model reasonably simulates the September and October changes in total ozone, considering the uncertainties in the observed data and the radiative heating. The simulated decline is found to be very sensitive to the choice of initial ozone profile and to small changes in the radiative heating. The results of this study suggest that the dynamical hypothesis of the Antarctic ozone depletion is both quantitatively credible and consistent with the observed temperature changes.

  15. Antarctic sea ice: Its development and basic properties

    International Nuclear Information System (INIS)

    The author reports investigations on sea ice properties carried out during a number of expeditions into the Weddell Sea, Antarctica. The results provide important baseline data, against which possible changes in the Antarctic sea ice cover as induced by climatic changes can be compared. This paper concentrates on results dealing with the textural properties and the ice thickness distributions of Antarctic sea ice. In addition, the author looks at the contribution of meteoric ice (snow ice) to the sea ice cover by means of δ18O measurements. While changes in extent and thickness are to be expected as a result of possible climatic warming, they propose that the amount of snow ice will serve as an additional indicator of such changes

  16. Remote Antarctic feeding ground important for east Australian humpback whales

    OpenAIRE

    Constantine, R.; Steel, D.; Allen, J.; Anderson, M; Andrews, O.; Baker, C.; Beeman, P.; Burns, D.; Charrassin, J. B.; Childerhouse, S.; Double, M; Ensor, P.; Franklin, T; Franklin, W; Gales, N.

    2014-01-01

    Understanding the dynamics of population recovery is particularly complex when an organism has multiple, remote breeding and feeding grounds separated by one of the longest known migration routes. This study reports on the most comprehensive assessment of humpback whale (Megaptera novaeangliae) movements between remote Antarctic waters south of New Zealand and east Australia (EA), and the migratory corridors and breeding grounds of Australia and Oceania. A total of 112 individual whales were ...

  17. Cyclone formation and development in the Antarctic Prydz Bay

    Institute of Scientific and Technical Information of China (English)

    解思梅; 梅山; 刘克威; 魏立新

    2002-01-01

    Using meteorological data of field observation in 1990~ 2000 , especially polar orbit highresolution NOAA satellite cloud maps received from the Antarctic expedition vessel since 1997, the formation and development of the Prydz Bay cyclone are studied in this paper. Some new viewpoints are suggested such as: when surround-polar cyclone enters the Prydz Bay, it can also intensify and develop in summer; cyclone can also develop in the easterlies in this bay. These view points revise old uncomplete view point that the Prydz Bay is a burial ground of cyclone, and also further consummate formation-development theory of surround-cyclone in the Antarctic westerlies and cyclone in the Antarctic easterlies. In this paper, the mechanism of ice-air-sea interaction in the Prydz Bay is studied, and the physical process of cyclone formation-development is explained. By use of wholly dynamic transportation method, an energy exchange case of a cyclone, which explosively developed after entering the Prydz Bay, is calculated. In the open water area, momentum flux is - 2.205 N/m2, sensible heat flux is 486.69 W/m2, and latent heat flux is 261.84 W/m2. It is larger than values of westerlies burst over the Pacific. The heat transferred from ocean to atmosphere in form of sensible and latent heat promotes cyclone development rapidly. In this case wind force was as strong as 12 grade, with 10 minutes average wind speed of 38 m/s, and instantaneous wind speed of 100 m/s which broke the wind speed record of 96 m/s in the Antarctic (Wendler and Kodama).

  18. Obliquity-paced Pliocene West Antarctic ice sheet oscillations

    Science.gov (United States)

    Naish, T.; Powell, R.; Levy, R.; Wilson, G.; Scherer, R.; Talarico, F.; Krissek, L.; Niessen, F.; Pompilio, M.; Wilson, T.; Carter, L.; DeConto, R.; Huybers, P.; McKay, R.; Pollard, D.; Ross, J.; Winter, D.; Barrett, P.; Browne, G.; Cody, R.; Cowan, E.; Crampton, J.; Dunbar, G.; Dunbar, N.; Florindo, F.; Gebhardt, C.; Graham, I.; Hannah, M.; Hansaraj, D.; Harwood, D.; Helling, D.; Henrys, S.; Hinnov, L.; Kuhn, G.; Kyle, P.; Laufer, A.; Maffioli, P.; Magens, D.; Mandernack, K.; McIntosh, W.; Millan, C.; Morin, R.; Ohneiser, C.; Paulsen, T.; Persico, D.; Raine, I.; Reed, J.; Riesselman, C.; Sagnotti, L.; Schmitt, D.; Sjunneskog, C.; Strong, P.; Taviani, M.; Vogel, S.; Wilch, T.; Williams, T.

    2009-01-01

    Thirty years after oxygen isotope records from microfossils deposited in ocean sediments confirmed the hypothesis that variations in the Earth's orbital geometry control the ice ages, fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles. Furthermore, an understanding of the behaviour of the marine-based West Antarctic ice sheet (WAIS) during the 'warmer-than-present' early-Pliocene epoch (???5-3 Myr ago) is needed to better constrain the possible range of ice-sheet behaviour in the context of future global warming. Here we present a marine glacial record from the upper 600 m of the AND-1B sediment core recovered from beneath the northwest part of the Ross ice shelf by the ANDRILL programme and demonstrate well-dated, ???40-kyr cyclic variations in ice-sheet extent linked to cycles in insolation influenced by changes in the Earth's axial tilt (obliquity) during the Pliocene. Our data provide direct evidence for orbitally induced oscillations in the WAIS, which periodically collapsed, resulting in a switch from grounded ice, or ice shelves, to open waters in the Ross embayment when planetary temperatures were up to ???3??C warmer than today and atmospheric CO 2 concentration was as high as ???400 p.p.m.v. (refs 5, 6). The evidence is consistent with a new ice-sheet/ice-shelf model that simulates fluctuations in Antarctic ice volume of up to +7 m in equivalent sea level associated with the loss of the WAIS and up to +3 m in equivalent sea level from the East Antarctic ice sheet, in response to ocean-induced melting paced by obliquity. During interglacial times, diatomaceous sediments indicate high surface-water productivity, minimal summer sea ice and air temperatures above freezing, suggesting an additional influence of surface melt under conditions of elevated CO2. ??2009 Macmillan Publishers Limited. All rights reserved.

  19. Testing olfactory foraging strategies in an Antarctic seabird assemblage

    OpenAIRE

    Nevitt, G A; Reid, K; Trathan, P.

    2004-01-01

    Procellariiform seabirds (petrels, albatrosses and shearwaters) forage over thousands of square kilometres for patchily distributed prey resources. While these birds are known for their large olfactory bulbs and excellent sense of smell, how they use odour cues to locate prey patches in the vast ocean is not well understood. Here, we investigate species-specific responses to 3-methyl pyrazine in a sub-Antarctic species assemblage near South Georgia Island (54degrees00' S, 36degrees00' W). Pyr...

  20. Ecological and Pharmacological Activities of Antarctic Marine Natural Products.

    Science.gov (United States)

    Avila, Conxita

    2016-06-01

    Antarctic benthic communities are regulated by abundant interactions of different types among organisms, such as predation, competition, etc. Predators are usually sea stars, with omnivorous habits, as well as other invertebrates. Against this strong predation pressure, many organisms have developed all sorts of defensive strategies, including chemical defenses. Natural products are thus quite common in Antarctic organisms with an important ecological and pharmacological potential. In this paper, the chemical defenses of the Antarctic organisms studied during the ECOQUIM and ACTIQUIM projects, as well as their pharmacological potential, are reviewed. For the ecological defenses, predation against the sea star Odontaster validus is analyzed and evaluated along depth gradients as well as considering the lifestyle of the organisms. For the pharmacological activity, the anticancer, anti-inflammatory, and antibacterial activities tested are evaluated here. Very often, only crude extracts or fractions have been tested so far, and therefore, the natural products responsible for such activities remain yet to be identified. Even if the sampling efforts are not uniform along depth, most ecologically active organisms are found between 200 and 500 m depth. Also, from the samples studied, about four times more sessile organisms possess chemical defenses against the sea star than the vagile ones; these represent 50 % of sessile organisms and 35 % of the vagile ones, out of the total tested, being active. Pharmacological activity has not been tested uniformly in all groups, but the results show that relevant activity is found in different phyla, especially in Porifera, Cnidaria, Bryozoa, and Tunicata, but also in others. No relationship between depth and pharmacological activity can be established with the samples tested so far. More studies are needed in order to better understand the ecological relationships among Antarctic invertebrates mediated by natural products and

  1. Atmospheric near surface nitrate at coastal Antarctic sites

    OpenAIRE

    D. Wagenbach; Legrand, M; Fischer, H.; Pichlmayer, F.; E. W. Wolff

    1998-01-01

    Records of atmospheric nitrate were obtained by year-round aerosol sampling at Neumayer and Dumont D'Urville stations, located in the Atlantic and Pacific sector of coastal Antarctica, respectively. Where possible, evaluation of the nitrate records is mainly based on concurrently measured radioisotopes (10Be, 7Be, 210Pb) as well as δ15N in nitrate nitrogen. Observations made at these (and two other coastal Antarctic sites [Savoie et al., 1993]) reveal a uniform nitrate background near 10 ng m...

  2. Ultraviolet radiation response of two heterotropy Antarctic marine bacterial

    International Nuclear Information System (INIS)

    Two Antarctic marine bacterial strains, were exposed to different irradiance of ultraviolet (UV) solar radiation using several experimental protocols and interferential filters. Results showed that both, UV-A and UV-B radiation produce deleterious effects on two tested bacterial strains. The mortality values under UVB treatments were higher than those observed under UVA treatments. UVvi strain proved to be more resistant to UV radiation than the UVps strain. (author)

  3. Antarctic sea ice losses drive gains in benthic carbon drawdown.

    Science.gov (United States)

    Barnes, D K A

    2015-09-21

    Climate forcing of sea-ice losses from the Arctic and West Antarctic are blueing the poles. These losses are accelerating, reducing Earth's albedo and increasing heat absorption. Subarctic forest (area expansion and increased growth) and ice-shelf losses (resulting in new phytoplankton blooms which are eaten by benthos) are the only significant described negative feedbacks acting to counteract the effects of increasing CO2 on a warming planet, together accounting for uptake of ∼10(7) tonnes of carbon per year. Most sea-ice loss to date has occurred over polar continental shelves, which are richly, but patchily, colonised by benthic animals. Most polar benthos feeds on microscopic algae (phytoplankton), which has shown increased blooms coincident with sea-ice losses. Here, growth responses of Antarctic shelf benthos to sea-ice losses and phytoplankton increases were investigated. Analysis of two decades of benthic collections showed strong increases in annual production of shelf seabed carbon in West Antarctic bryozoans. These were calculated to have nearly doubled to >2x10(5) tonnes of carbon per year since the 1980s. Annual production of bryozoans is median within wider Antarctic benthos, so upscaling to include other benthos (combined study species typically constitute ∼3% benthic biomass) suggests an increased drawdown of ∼2.9x10(6) tonnes of carbon per year. This drawdown could become sequestration because polar continental shelves are typically deeper than most modern iceberg scouring, bacterial breakdown rates are slow, and benthos is easily buried. To date, most sea-ice losses have been Arctic, so, if hyperboreal benthos shows a similar increase in drawdown, polar continental shelves would represent Earth's largest negative feedback to climate change. PMID:26394097

  4. Mantle domain and segmentation at the Australian-Antarctic Ridge

    Science.gov (United States)

    Park, S. H.; Langmuir, C. H.; Lin, J.; Kim, S.; Hahm, D.; Michael, P. J.; Scott, S. R.; Sims, K. W. W.

    2014-12-01

    The Australian-Antarctic ridge (AAR) is the largest unexplored expanse of the global mid-ocean ridges. Using the Korean Icebreaker Araon, we carried out a multi-disciplinary study of two segments (KR1 and KR2) of intermediate spreading AAR in three expeditions from 2011 to 2013. KR1, a 300-km-long supersegment located in the center of AAR, has large transform faults at its two ends, only small 3rd and 4th order offsets between the transforms, and no overlapping spreading centers. Nonetheless there are large variations in axial morphology from axial high to rift valley, as well as large changes in chemical and Pb isotopic composition. The KR2 segment is located about 200 km northwest of KR1 and connected to it by the Balleny transform. KR2 is a 180 km-long 1st order segment bounded by two transforms and consists of a western segment with axial high and an eastern segment with rift valley. Along-axis geochemical variations indicate that the magma flux and ridge morphology of are influenced by changing mantle composition on a fine scale, and thus magma transport to the crust must occur at multiple locations along this single segment. Both the KR1 and KR2 segments are on the Pacific side of the Australian-Antarctic-Discordance, long considered as the boundary between Pacific and Indian mantle. However, isotopic and trace elements data of these segments differ from samples from the Pacific-Antarctic Ridge, so flow of Pacific mantle into Indian mantle bounded by the Australian-Antarctic-Discordance is no longer supported.

  5. Antarctic Ice Sheet and Radar Altimetry: A Review

    OpenAIRE

    Frédérique Rémy; Soazig Parouty

    2009-01-01

    International audience Altimetry is probably one of the most powerful tools for ice sheet observation. Our vision of the Antarctic ice sheet has been deeply transformed since the launch of the ERS1 satellite in 1991. With the launch of ERS2 and Envisat, the series of altimetric observations now provides 19 years of continuous and homogeneous observations that allow monitoring of the shape and volume of ice sheets. The topography deduced from altimetry is one of the relevant parameters reve...

  6. Blue and fin whale acoustics and ecology off Antarctic Peninsula

    OpenAIRE

    Sirovic, Ana

    2006-01-01

    Blue (Balaenoptera musculus) and fin whales (B. physalus) in the Southern Ocean were subjects of extensive whaling industry during the twentieth century. Their current population numbers remain low, making population monitoring using traditional visual surveys difficult. Both blue and fin whales produce low frequency, regularly repeated calls and are suitable for acoustic monitoring. Eight, continuously recording acoustic recorders were deployed off the Western Antarctic Peninsula (WAP) betwe...

  7. Is the species flock concept operational? The Antarctic Shelf case

    OpenAIRE

    Guillaume Lecointre; Nadia Améziane; Marie-Catherine Boisselier; Céline Bonillo; Frédéric Busson; Romain Causse; Anne Chenuil; Arnaud Couloux; Jean-Pierre Coutanceau; Corinne Cruaud; Cédric d'Udekem d'Acoz; Chantal De Ridder; Gael Denys; Agnès Dettaï; Guy Duhamel

    2013-01-01

    There has been a significant body of literature on species flock definition but not so much about practical means to appraise them. We here apply the five criteria of Eastman and McCune for detecting species flocks in four taxonomic components of the benthic fauna of the Antarctic shelf: teleost fishes, crinoids (feather stars), echinoids (sea urchins) and crustacean arthropods. Practical limitations led us to prioritize the three historical criteria (endemicity, monophyly, species richness) ...

  8. First record of Babesia sp. in Antarctic penguins.

    Science.gov (United States)

    Montero, Estrella; González, Luis Miguel; Chaparro, Alberto; Benzal, Jesús; Bertellotti, Marcelo; Masero, José A; Colominas-Ciuró, Roger; Vidal, Virginia; Barbosa, Andrés

    2016-04-01

    This is the first reported case of Babesia sp. in Antarctic penguins, specifically a population of Chinstrap penguins (Pygoscelis antarctica) in the Vapour Col penguin rookery in Deception Island, South Shetlands, Antarctica. We collected peripheral blood from 50 adult and 30 chick Chinstrap penguins. Examination of the samples by microscopy showed intraerythrocytic forms morphologically similar to other avian Babesia species in 12 Chinstrap penguin adults and seven chicks. The estimated parasitaemias ranged from 0.25×10(-2)% to 0.75×10(-2)%. Despite the low number of parasites found in blood smears, semi-nested PCR assays yielded a 274bp fragment in 12 of the 19 positive blood samples found by microscopy. Sequencing revealed that the fragment was 97% similar to Babesia sp. 18S rRNA from Australian Little Penguins (Eudyptula minor) confirming presence of the parasite. Parasite prevalence estimated by microscopy in adults and chicks was higher (24% vs. 23.3%, respectively) than found by semi-nested PCR (16% vs. 13.3% respectively). Although sampled penguins were apparently healthy, the effect of Babesia infection in these penguins is unknown. The identification of Babesia sp. in Antarctic penguins is an important finding. Ixodes uriae, as the only tick species present in the Antarctic Peninsula, is the key to understanding the natural history of this parasite. Future work should address the transmission dynamics and pathogenicity of Babesia sp. in Chinstrap penguin as well as in other penguin species, such as Gentoo penguin (Pygoscelis papua) and Adélie penguin (Pygoscelis adeliae), present within the tick distribution range in the Antarctic Peninsula. PMID:26874670

  9. Acclimation and thermal tolerance in Antarctic marine ectotherms

    OpenAIRE

    Peck, L.S.; Morley, S.A.; Richard, J.; Clark, M.S.

    2014-01-01

    Antarctic marine species have evolved in one of the coldest and most temperature-stable marine environments on Earth. They have long been classified as being stenothermal, or having a poor capacity to resist warming. Here we show that their ability to acclimate their physiology to elevated temperatures is poor compared with species from temperate latitudes, and similar to those from the tropics. Those species that have been demonstrated to acclimate take a very long time to do so, with Antarc...

  10. Phylogenetic position of Antarctic Scalpelliformes (Crustacea: Cirripedia: Thoracica)

    Science.gov (United States)

    Linse, Katrin; Jackson, Jennifer A.; Fitzcharles, Elaine; Sands, Chester J.; Buckeridge, John S.

    2013-03-01

    The phylogenetic relationships of seven Antarctic barnacle species, one verrucomorph and six scalpelliforms from the Scotia, Weddell and Ross seas were investigated using DNA sequences from two nuclear genes (18 S and 28 S) and one mitochondrial gene (COI), with a combined total length of 3,151 base pairs. Analyses of these new sequences, together with those of previously published ibliform, lepadiform, scalpelliform, balanomorph and verrucomorph species, confirm that the Scalpelliformes are not monophyletic. Bayesian and maximum likelihood analyses consistently recovered a monophyletic group which comprised Ornatoscalpellum stroemii (Sars) and the Southern Ocean scalpellomorphs; Arcoscalpellum sp. from the Weddell Sea, Arcoscalpellum africanum from Elephant Island, A. bouveti from Bouvet Island, the circum-Antarctic Litoscalpellum discoveryi, Litoscalpellum sp. from Shag Rocks and Scalpellum sp. from the Falkland Trough. We also used multiple fossil constraints in a relaxed clock Bayesian framework to estimate divergence times for the 18 S+28 S phylogeny. Our results indicate a mid Cretaceous divergence for the Weddell Sea Arcoscalpellum sp, followed by a late Cretaceous divergence from the North Atlantic O. stroemii. Subsequent to this, the Antarctic scalpellomorphs began to radiate at the Cretaceous-Tertiary boundary. Monophyly within the scalpellid genera Arcoscalpellum, Litoscalpellum and Scalpellum was strongly rejected by all loci. Our results show incongruence between taxonomy and molecular systematics and highlight the need for more species to be sequenced as well as taxonomic revisions to resolve uncertainties in the phylogenetic relationships of the stalked barnacles.

  11. Antarctic birds (Neornithes during the Cretaceous-Eocene times

    Directory of Open Access Journals (Sweden)

    C. Tambussi

    2007-12-01

    Full Text Available Antarctic fossil birds can be confidently assigned to modern orders and families, such as a goose-like anseriform, two loon-like and a seriema-like, all recorded before the K/T boundary at the López de Bertodano Fomation. Also, the discovery of a ratite and a phororhacids from the uppermost levels of the Submeseta Allomember (Late Eocene, suggests that West Antarctica was functional to dispersal routes obligate terrestrial birds. Representatives of Falconiformes Polyborinae, Ciconiiformes, Phoenicoteriformes, Charadriiformes, Pelagornitidae and Diomedeidae constitute the non-penguin avian assemblages of the Eocene of La Meseta Formation. Fifthteen Antarctic species of penguins have been described including the oldest penguin of West Antarctica, Croswallia unienwillia. The Anthropornis nordenskjoeldi Biozone (36.13 and 34.2 Ma, Late Eocene is characterized by bearing one of the highest frequencies of penguin bones and the phospatic brachiopod Lingula., together with remains of Gadiforms, sharks and primitive mysticete whales. Anthropornis nordenskjoeldi, Delphinornis gracilis, D. arctowski, Archaeospheniscus lopdelli, and Palaeeudyptes antarcticus are exclusively of the La Meseta Formation. Anthropornis nordenskjoeldi was evidently the largest penguin recorded at the James Ross Basin, whereas Delphinornis arctowski is the smallest, and include one of the worldwide highest morphological and taxonomic penguin diversity living sympatrically. The progressive climate cooling of the Eocene could have affected the penguin populations, because of climatic changes linked with habitat availability and food web processes. However, there is not available evidence about Antarctic penguins' evolution after the end of the Eocene.

  12. A transcriptome resource for the Antarctic pteropod Limacina helicina antarctica.

    Science.gov (United States)

    Johnson, Kevin M; Hofmann, Gretchen E

    2016-08-01

    The pteropod Limacina helicina antarctica is a dominant member of the zooplankton assemblage in the Antarctic marine ecosystem, and is part of a relatively simple food web in nearshore marine Antarctic waters. As a shelled pteropod, Limacina has been suggested as a candidate sentinel organism for the impacts of ocean acidification, due to the potential for shell dissolution in undersaturated waters. In this study, our goal was to develop a transcriptomic resource for Limacina that would support mechanistic studies to explore the physiological response of Limacina to abiotic stressors such as ocean acidification and ocean warming. To this end, RNA sequencing libraries were prepared from Limacina that had been exposed to a range of pH levels and an elevated temperature to maximize the diversity of expressed genes. RNA sequencing (RNA-seq) was conducted on an Illumina NextSeq500 which produced 339,000,000 150bp paired-end reads. The de novo transcriptome was produced using Trinity and annotation of the assembled transcriptome resulted in the identification of 81,229 transcripts in 137 KEGG pathways. This RNA-seq effort resulted in a transcriptome for the Antarctic pteropod, Limacina helicina antarctica, that is a major resource for an international marine science research community studying these pelagic molluscs in a global change context. PMID:27157132

  13. Metagenomic Analysis of Bacterial Communities of Antarctic Surface Snow

    Directory of Open Access Journals (Sweden)

    Anna Lopatina

    2016-03-01

    Full Text Available The diversity of bacteria present in surface snow around four Russian stations in Eastern Antarctica was studied by high throughput sequencing of amplified 16S rRNA gene fragments and shotgun metagenomic sequencing. Considerable class- and genus-level variation between the samples was revealed indicating a presence of inter-site diversity of bacteria in Antarctic snow. Flavobacterium was a major genus in one sampling site and was also detected in other sites. The diversity of flavobacterial type II-C CRISPR spacers in the samples was investigated by metagenome sequencing. Thousands of unique spacers were revealed with less than 35% overlap between the sampling sites, indicating an enormous natural variety of flavobacterial CRISPR spacers and, by extension, high level of adaptive activity of the corresponding CRISPR-Cas system. None of the spacers matched known spacers of flavobacterial isolates from the Northern hemisphere. Moreover, the percentage of spacers with matches with Antarctic metagenomic sequences obtained in this work was significantly higher than with sequences from much larger publically available environmental metagenomic database. The results indicate that despite the overall very high level of diversity, Antarctic Flavobacteria comprise a separate pool that experiences pressures from mobile genetic elements different from those present in other parts of the world. The results also establish analysis of metagenomic CRISPR spacer content as a powerful tool to study bacterial populations diversity.

  14. Extent of Low-accumulation 'Wind Glaze' Areas on the East Antarctic Plateau: Implications for Continental Ice Mass Balance

    Science.gov (United States)

    Scambos, Theodore A.; Frezzotti, Massimo; Haran, T.; Bohlander, J.; Lenaerts, J. T. M.; Van Den Broeke, M. R.; Jezek, K.; Long, D.; Urbini, S.; Farness, K.; Neumann, T.; Albert, M.; Winther, J.-G.

    2012-01-01

    Persistent katabatic winds form widely distributed localized areas of near-zero net surface accumulation on the East Antarctic ice sheet (EAIS) plateau. These areas have been called 'glaze' surfaces due to their polished appearance. They are typically 2-200 square kilometers in area and are found on leeward slopes of ice-sheet undulations and megadunes. Adjacent, leeward high-accumulation regions (isolated dunes) are generally smaller and do not compensate for the local low in surface mass balance (SMB). We use a combination of satellite remote sensing and field-gathered datasets to map the extent of wind glaze in the EAIS above 1500m elevation. Mapping criteria are derived from distinctive surface and subsurface characteristics of glaze areas resulting from many years of intense annual temperature cycling without significant burial. Our results show that 11.2 plus or minus 1.7%, or 950 plus or minus 143 x 10(exp 3) square kilometers, of the EAIS above 1500m is wind glaze. Studies of SMB interpolate values across glaze regions, leading to overestimates of net mass input. Using our derived wind-glaze extent, we estimate this excess in three recent models of Antarctic SMB at 46-82 Gt. The lowest-input model appears to best match the mean in regions of extensive wind glaze.

  15. Ocean-atmosphere exchange of organic carbon and CO2 in the Antarctic Peninsula – physical and biological controls

    Directory of Open Access Journals (Sweden)

    S. Ruiz-Halpern

    2013-10-01

    Full Text Available Exchangeable organic carbon (OC dynamics and CO2 fluxes in the Antarctic Peninsula region during austral summer are highly variable. By stations, the region is a weak source of CO2 to the atmosphere, however, continuous records of CO2 revealed this area as a weak sink. OC fluxes are also in both directions but generally towards the ocean and much higher than CO2 fluxes, sometimes by a factor of 10. Surface exchangeable dissolved organic carbon (EDOC measurements had a 43 ± 3 μmol C L−1 overall mean, while the gaseous organic carbon equilibrated in water as given by the Henry's Law constant (H' resulted in (GOC H'−1 concentrations of 46 ± 3 μmol C L−1. EDOC represents around 66% of surface dissolved organic carbon (DOC in Antarctic waters. There is a tendency towards low partial pressures of CO2 in waters with high Chlorophyll a (Chl a content and high fCO2 in areas with high krill densities. However, such relationships were not found for EDOC. Depth profiles of EDOC were also quite variable and followed Chl a profiles, but only in some instances, while diel cycles of EDOC revealed two distinct peaks around midday and middle of the short austral dark period concurrent with solar radiation maxima and krill night migration patterns. However, there was no evident diel pattern for GOC H'−1. The pool of exchangeable OC reveals itself as an important compartment of the carbon budget in the Antarctic Peninsula and adds to previous studies highlighting its importance in the redistribution of carbon in marine environments.

  16. The effect of environmental change on vascular plant and cryptogam communities from the Falkland Islands and the Maritime Antarctic

    Directory of Open Access Journals (Sweden)

    Convey Peter

    2007-12-01

    Full Text Available Abstract Background Antarctic terrestrial vegetation is subject to one of the most extreme climates on Earth. Currently, parts of Antarctica are one of the fastest warming regions on the planet. During 3 growing seasons, we investigated the effect of experimental warming on the diversity and abundance of coastal plant communities in the Maritime Antarctic region (cryptogams only and the Falkland Islands (vascular plants only. We compared communities from the Falkland Islands (51°S, mean annual temperature 7.9°C, with those of Signy Island (60°S, -2.1°C and Anchorage Island (67°S, -2.6°C, and experimental temperature manipulations at each of the three islands using Open Top Chambers (OTCs. Results Despite the strong difference in plant growth form dominance between the Falkland Islands and the Maritime Antarctic, communities across the gradient did not differ in total diversity and species number. During the summer months, the experimental temperature increase at 5 cm height in the vegetation was similar between the locations (0.7°C across the study. In general, the response to this experimental warming was low. Total lichen cover showed a non-significant decreasing trend at Signy Island (p Conclusion These results suggest that small temperature increases may rapidly lead to decreased soil moisture, resulting in more stressful conditions for plants. The more open plant communities (grass and lichen appeared more negatively affected by such changes than dense communities (dwarf shrub and moss.

  17. Carbon fluxes to Antarctic top predators

    NARCIS (Netherlands)

    Franeker, van J.A.; Bathmann, U.V.; Mathot, S.

    1997-01-01

    The role of birds, seals and whales in the overall biological carbon fluxes of the Southern Ocean has been estimated based on census counts of top predator individuals in the region. Using standard routines for conversion to food consumption and respiration rates we demonstrate that at most 0.3-0.6%

  18. Environmental monitoring and management proposals for the Fildes Region, King George Island, Antarctica

    OpenAIRE

    Braun, Christina; Mustafa, Osama; Nordt, Anja; Pfeiffer, Simone; Peter, Hans-Ulrich

    2012-01-01

    The Antarctic terrestrial environment is under increasing pressure from human activities. The Fildes Region is characterized by high biodiversity, but is also a major logistic centre for the northern Antarctic Peninsula. Different interests, from scientific research, nature conservation, protection of geological and historical values, station operations, transport logistics and tourism, regularly overlap in space and time. This has led to increasing conflict among the multiple uses of the reg...

  19. THE EVOLUTION OF UPPER WATER STRUCTURE IN THE PRYDZ BAY POLYNYA REGION DURING ANTARCTIC WINTER,2011%2011年初冬南极普里兹湾冰间湖区上层水体结构演化研究

    Institute of Scientific and Technical Information of China (English)

    高郭平; 闫敏斐; 徐智昕; 程灵巧; 张春玲

    2016-01-01

    利用5头活动于南极普里兹湾的象海豹携带的 CTD 观测获得的2011年3—6月埃默里冰架前缘冰间湖区域海水温盐剖面数据,研究了该海域上层水体结构在初冬的演化过程。结果显示,可将该演化过程分为三个阶段:第一阶段海水温度从层化到均匀,3月下旬次表层仍维持暖水特征,随着表层海水冷却作用,次表层暖水逐渐消失,上下水体温度趋于均匀并接近冰点,温度剖面从“逆温型”演变到“均匀型”;第二阶段海水盐度从层化到上下均匀,也就是从“均匀型”演变到“渐变型”,海水结冰析盐过程使上层海水盐度增加,增强垂直对流混合,上下层盐度达到均匀;第三阶段冷却结冰持续,海水盐度继续增大,形成盐度随深度减小、温度随深度增大的“渐变型”结构。根据温盐剖面数据计算三个阶段的海-气之间的热通量分别是-90.93、-82.20和-43.44 W·m -2。考虑海水盐分的增加主要源于海冰形成,由此推算三个阶段内平均的海冰形成速率分别是5.4、4.9和2.5 cm·d -1。在南极初冬时期,随着海水上层低温高盐化演变持续,海水向大气释放的热通量逐渐减少,海冰形成速率也呈减少趋势。%Hydrographic data collected during the early Antarctic winter 201 1 by CTD tags fitted to five elephant seals were analyzed to study the evolution of the upper water layer in the Prydz Bay polynya adjacent to the Amery Ice Shelf.The evolution of upper ocean structure could be divided into three stages.First,temperature shifted from a stratified profile to homogeneity.Warm water was still present in the subsurface in late March.This warm water gradually disappeared with cooling of the surface water,so the temperature profile evolved from temperature inver-sion to homogeneity at temperatures close to freezing.Second,salinity shifted from a stratified profile to

  20. Functional ecology of an Antarctic Dry Valley

    OpenAIRE

    Chan, Yuki; Joy D Van Nostrand; Zhou, Jizhong; Pointing, Stephen B.; Farrell, Roberta L.

    2013-01-01

    The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are critically at risk from climate change. The terrestrial landscape is dominated by oligotrophic mineral soils and extensive exposed rocky surfaces where biota are largely restricted to microbial communities, although their ability to perform the majority of geobiological processes has remained largely uncharacterized. Here, we identified functional traits that drive microbial survival and community assembly, using a ...

  1. High geothermal heat flux measured below the West Antarctic Ice Sheet.

    Science.gov (United States)

    Fisher, Andrew T; Mankoff, Kenneth D; Tulaczyk, Slawek M; Tyler, Scott W; Foley, Neil

    2015-07-01

    The geothermal heat flux is a critical thermal boundary condition that influences the melting, flow, and mass balance of ice sheets, but measurements of this parameter are difficult to make in ice-covered regions. We report the first direct measurement of geothermal heat flux into the base of the West Antarctic Ice Sheet (WAIS), below Subglacial Lake Whillans, determined from the thermal gradient and the thermal conductivity of sediment under the lake. The heat flux at this site is 285 ± 80 mW/m(2), significantly higher than the continental and regional averages estimated for this site using regional geophysical and glaciological models. Independent temperature measurements in the ice indicate an upward heat flux through the WAIS of 105 ± 13 mW/m(2). The difference between these heat flux values could contribute to basal melting and/or be advected from Subglacial Lake Whillans by flowing water. The high geothermal heat flux may help to explain why ice streams and subglacial lakes are so abundant and dynamic in this region. PMID:26601210

  2. An Observation of Antarctic Marginal Subglacial Lake using Cryosat-2 SARin mode

    Science.gov (United States)

    Kim, B.; Lee, C. K.; Seo, K. W.

    2015-12-01

    The surface height above active subglacial lake (SGL) varies in accordance with the water storage of lake beneath ice-sheet. Thus, satellite altimeters accurately measuring the ice surface height have discovered numbers of SGLs. In this study, we detect Antarctic SGLs using Cryosat-2 without any auxiliary data. The SARin mode of Cyrosat-2 is designed to retrieve the elevation over steep slope regions, such as margin of ice-sheet or ice-stream. The high-resolution processing of SARin mode yielding the elevation change rate (=Δh/Δt) enables us to verify the specific 2-D boundary of lake and even the small-scale uncategorized lakes. In the Whillans and Mercer Ice Streams (WIS and MIS), drainage or refilling events of 9 SGLs are apparent in Cyrosat-2 era, and one of those is likely an uncategorized lake. In addition, the ice thickening upstream of WIS and MIS, which might be provoked by the deceleration downstream of WIS, alternates between high and low rate. It might be associated with massive drainage event of lake "Conway". In the Kamb Ice Stream (KIS), most of previously known SGLs are not observed except for only one (Kamb trunk1) due to the limited spatial coverage of SARin mode operation. However, two additional lakes (located in 82.304S/147.980W and 82.477S/150.585W, respectively) are discovered at the downstream of Kamb trunk 1 lake. Similar approach is applied at slightly rugged terrain, which is located on the upstream of David Glacier. The drainage event of David 1 SGL is apparent, but the precise location of the lake is significantly (about twenty kilometers) different from previous ICESat measurement. Since ICESat measurements have limited temporal/spatial resolutions, we expect that Cryosat-2 have more optimal performance for measuring Antarctic Marginal SGLs.

  3. Potential sea-level rise from Antarctic ice-sheet instability constrained by observations

    Science.gov (United States)

    Ritz, Catherine; Edwards, Tamsin L.; Durand, Gaël; Payne, Antony J.; Peyaud, Vincent; Hindmarsh, Richard C. A.

    2015-12-01

    Large parts of the Antarctic ice sheet lying on bedrock below sea level may be vulnerable to marine-ice-sheet instability (MISI), a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-level rise. If triggered in other regions, the centennial to millennial contribution could be several metres. Physically plausible projections are challenging: numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive to generate large ensembles for uncertainty assessment, and lower-resolution model projections rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B (ref. 9), although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers.

  4. Velocity of small-scale auroral ionospheric current systems over Indian Antarctic station Maitri

    Indian Academy of Sciences (India)

    Girija Rajaram; A N Hanchinal; R Kalra; K Unnikrishnan; K Jeeva; M Sridharan; A Dhar

    2002-03-01

    The Indian Antarctic station Maitri (geog. 70° 45/S, 11° 45/E, geom. 66° .03S, 53°.21E) occupies a sub-auroral location during magnetically quiet conditions ( Kp < 10), but attains an auroral position when the auroral oval shifts equatorwards with increasing strength of magnetic disturbance. At the latter times, triangulation with 3 uxgate magnetometers located at the vertices of a suitable triangle provides a means of monitoring mobile auroral ionospheric current systems over Maitri. The spacing between the magnetometers is typically kept at 75-200 km, keeping in mind the scale-sizes of ∼100 km for these mobile current systems. This work reports the results of two triangulation experiments carried out around Maitri in January 1992 and January 1995, both during Antarctic summer. The velocities estimated for pulsations of the Pc4 and Pc5 type were about 0.59 km/sec in the direction 102°.7 east of due north, in the first case, and about 1-3 km/sec in the second case in the east-west direction. While several magnetometer arrays exist in the northern auroral regions (e.g., the Alberta array in Canada, the Alaskan array in the U.S. and the IMS Scandinavian array), there is no report in literature of triangulation through arrays in Antarctica, except for a one-day study by Neudegg et al 1995 for ULF pulsations of the Pc1 and Pc2 type. The velocities obtained for the Pi3 type of irregular pulsations over Antarctica in the present study tally well with those obtained for northern auroral locations.

  5. Genome-based comparative analyses of Antarctic and temperate species of Paenibacillus.

    Directory of Open Access Journals (Sweden)

    Melissa Dsouza

    Full Text Available Antarctic soils represent a unique environment characterised by extremes of temperature, salinity, elevated UV radiation, low nutrient and low water content. Despite the harshness of this environment, members of 15 bacterial phyla have been identified in soils of the Ross Sea Region (RSR. However, the survival mechanisms and ecological roles of these phyla are largely unknown. The aim of this study was to investigate whether strains of Paenibacillus darwinianus owe their resilience to substantial genomic changes. For this, genome-based comparative analyses were performed on three P. darwinianus strains, isolated from gamma-irradiated RSR soils, together with nine temperate, soil-dwelling Paenibacillus spp. The genome of each strain was sequenced to over 1,000-fold coverage, then assembled into contigs totalling approximately 3 Mbp per genome. Based on the occurrence of essential, single-copy genes, genome completeness was estimated at approximately 88%. Genome analysis revealed between 3,043-3,091 protein-coding sequences (CDSs, primarily associated with two-component systems, sigma factors, transporters, sporulation and genes induced by cold-shock, oxidative and osmotic stresses. These comparative analyses provide an insight into the metabolic potential of P. darwinianus, revealing potential adaptive mechanisms for survival in Antarctic soils. However, a large proportion of these mechanisms were also identified in temperate Paenibacillus spp., suggesting that these mechanisms are beneficial for growth and survival in a range of soil environments. These analyses have also revealed that the P. darwinianus genomes contain significantly fewer CDSs and have a lower paralogous content. Notwithstanding the incompleteness of the assemblies, the large differences in genome sizes, determined by the number of genes in paralogous clusters and the CDS content, are indicative of genome content scaling. Finally, these sequences are a resource for further

  6. Snow depth on Arctic and Antarctic sea ice derived from autonomous (Snow Buoy) measurements

    Science.gov (United States)

    Nicolaus, Marcel; Arndt, Stefanie; Hendricks, Stefan; Heygster, Georg; Huntemann, Marcus; Katlein, Christian; Langevin, Danielle; Rossmann, Leonard; Schwegmann, Sandra

    2016-04-01

    The snow cover on sea ice received more and more attention in recent sea ice studies and model simulations, because its physical properties dominate many sea ice and upper ocean processes. In particular; the temporal and spatial distribution of snow depth is of crucial importance for the energy and mass budgets of sea ice, as well as for the interaction with the atmosphere and the oceanic freshwater budget. Snow depth is also a crucial parameter for sea ice thickness retrieval algorithms from satellite altimetry data. Recent time series of Arctic sea ice volume only use monthly snow depth climatology, which cannot take into account annual changes of the snow depth and its properties. For Antarctic sea ice, no such climatology is available. With a few exceptions, snow depth on sea ice is determined from manual in-situ measurements with very limited coverage of space and time. Hence the need for more consistent observational data sets of snow depth on sea ice is frequently highlighted. Here, we present time series measurements of snow depths on Antarctic and Arctic sea ice, recorded by an innovative and affordable platform. This Snow Buoy is optimized to autonomously monitor the evolution of snow depth on sea ice and will allow new insights into its seasonality. In addition, the instruments report air temperature and atmospheric pressure directly into different international networks, e.g. the Global Telecommunication System (GTS) and the International Arctic Buoy Programme (IABP). We introduce the Snow Buoy concept together with technical specifications and results on data quality, reliability, and performance of the units. We highlight the findings from four buoys, which simultaneously drifted through the Weddell Sea for more than 1.5 years, revealing unique information on characteristic regional and seasonal differences. Finally, results from seven snow buoys co-deployed on Arctic sea ice throughout the winter season 2015/16 suggest the great importance of local

  7. When shape matters: strategies of different Antarctic ascidians morphotypes to deal with sedimentation.

    Science.gov (United States)

    Torre, Luciana; Abele, Doris; Lagger, Cristian; Momo, Fernando; Sahade, Ricardo

    2014-08-01

    Climate change leads to increased melting of tidewater glaciers in the Western Antarctic Peninsula region and sediment bearing glacial melt waters negatively affects filter feeding species as solitary ascidians. In previous work the erect-forms Molgula pedunculata and Cnemidocarpa verrucosa (Order Stolidobranchiata) appeared more sensitive than the flat form Ascidia challengeri (Order Phlebobranchiata). Sedimentation exposure is expected to induce up-regulation of anaerobic metabolism by obstructing the organs of gas exchange (environmental hypoxia) or causes enhanced squirting activity (functional hypoxia). In this study we evaluated the possible relationship between ascidian morphotype and their physiological response to sedimentation. Together with some behavioural observations, we analysed the response of anaerobic metabolic parameters (lactate formation and glycogen consumption) in different tissues of three Antarctic ascidians, exposed to high sediment concentrations (200 mgL(-1)). The results were compared to experimental hypoxia (10% pO2) and exercise (induced muscular contraction) effects, in order to discriminate the effect of sediment on each species and morpho-type (erect vs. flat forms). Our results suggest that the styled (erect) C. verrucosa increases muscular squirting activity in order to expulse excessive material, while the flat-form A. challengeri reacts more passively by down-regulating its aerobic metabolism under sediment exposure. Contrary, the erect ascidian M. pedunculata did not show any measurable response to the treatments, indicating that filtration and ingestion activities were not reduced or altered even under high sedimentation (low energetic material) which could be disadvantageous on the long-term and could explain why M. pedunculata densities decline in the study area. PMID:24986145

  8. On the cryogenic removal of NOy from the Antarctic polar stratosphere

    Directory of Open Access Journals (Sweden)

    S. Smyshlyaev

    2003-06-01

    Full Text Available We review current knowledge about the annual cycle of transport of nitrogen oxides to, and removal from, the polar stratosphere, with particular attention to Antarctica where the annual winter denitrifi cation process is both regular in occurrence and severe in effect. Evidence for a large downward fl ux of NOy from the mesosphere to the stratosphere, fi rst seen briefl y in the Limb Infrared Monitor of the Stratosphere (LIMS data from the Arctic winter of 1978-1979, has been found during the 1990s in both satellite and ground-based observations, though this still seems to be omitted from many atmospheric models. When incorporated in the Stony Brook- St. Petersburg two dimensional (2D transport and chemistry model, more realistic treatment of the NOy fl ux, along with sulfate transport from the mesosphere, sulfate aerosol formation where temperature is favorable, and the inclusion of a simple ion-cluster reaction, leads to good agreement with observed HNO3 formation in the mid-winter middle to upper stratosphere. To further emphasize the importance of large fl uxes of thermospheric and mesospheric NOy into the polar stratosphere, we have used observations, supplemented with model calculations, to defi ne new altitude dependent correlation curves between N2O and NOy. These are more suitable than those previously used in the literature to represent conditions within the Antarctic vortex region prior to and during denitrifi cation by Polar Stratospheric Cloud (PSC particles. Our NOy -N2O curves lead to a 40% increase in the average amount of NOy removed during the Antarctic winter with respect to estimates calculated using NOy-N2O curves from the Atmospheric Trace Molecule Spectroscopy (ATMOS/ATLAS-3 data set.

  9. A synthesis of the antarctic surface mass balance during the last eight centuries

    Directory of Open Access Journals (Sweden)

    M. Frezzotti

    2012-02-01

    Full Text Available Global climate models suggest that Antarctic snowfall should increase in a warming climate and mitigate sea level rise, mainly due to the greater moisture-holding capacity of the warmer atmosphere. Several processes act on snow accumulation or surface mass balance (SMB, introducing large uncertainties in the past, present, and future ice sheet mass balance. To provide an extended past perspective of the SMB of Antarctica, we used 66 firn/ice core records to reconstruct the temporal variability over the past eight centuries and in greater detail over the last two centuries. Our SMB reconstructions show that the changes over most of Antarctica are statistically negligible and the current SMB is not exceptionally high compared with the last eight centuries. However, a clear increase in accumulation of more than 10 % has occurred in high SMB coastal regions and over the highest part of the East Antarctic ice divide since 1960s. To explain the different behaviours between the coastal/ice divide sites and rest of Antarctica, we suggest that a higher frequency of blocking-anticyclones increases the precipitation at coastal sites, leading to the advection of moist air at the highest areas, whereas blowing snow and/or erosion have significant negative impacts on the SMB at windy sites. Eight centuries of SMB stacked records mirror the total solar irradiance, suggesting a link between the southern position of the Pacific Intertropical Convergence Zone and atmospheric circulation in Antarctica through the generation and propagation of a large-scale atmospheric wave train. Decadal records of the last eight centuries show that the observed increase in accumulation is not anomalous at the continental scale; indeed, high accumulation periods have also occurred in the past, during the 1370s and 1610s.

  10. Antarctic Bottom Water temperature changes in the western South Atlantic from 1989 to 2014

    Science.gov (United States)

    Johnson, Gregory C.; McTaggart, Kristene E.; Wanninkhof, Rik

    2014-12-01

    Warming of abyssal waters in recent decades contributes to global heat uptake and sea level rise. Repeat oceanographic section data in the western South Atlantic taken mostly in 1989 (1995 across the Scotia Sea), 2005, and 2014 are used to quantify warming in abyssal waters that spread northward through the region from their Antarctic origins in the Weddell Sea. While much of the Scotia Sea warmed between 1995 and 2005, only the southernmost portion, on the north side of the Weddell Gyre, continued to warm between 2005 and 2014. The abyssal Argentine Basin also warmed between 1989 and 2005, but again only the southernmost portion continued to warm between 2005 and 2014, suggesting a slowdown in the inflow of the coldest, densest Antarctic Bottom Waters into the western South Atlantic between 1989 and 2014. In contrast, the abyssal waters of the Brazil Basin warmed both between 1989 and 2005 and between 2005 and 2014, at a rate of about 2 m°C yr-1. This warming is also assessed in terms of the rates of change of heights above the bottom for deep isotherms in each deep basin studied. These results, together with findings from previous studies, suggest the deep warming signal observed in the Weddell Sea after the mid-1970s Weddell Polynya was followed by abyssal warming in the Argentine Basin from the late 1970s through about 2005, then warming in the deep Vema Channel from about 1992 through at least 2010, and warming in the Brazil Basin from 1989 to 2014.

  11. Empirical estimation of present-day Antarctic glacial isostatic adjustment and ice mass change

    Science.gov (United States)

    Gunter, B. C.; Didova, O.; Riva, R. E. M.; Ligtenberg, S. R. M.; Lenaerts, J. T. M.; King, M. A.; van den Broeke, M. R.; Urban, T.

    2014-04-01

    This study explores an approach that simultaneously estimates Antarctic mass balance and glacial isostatic adjustment (GIA) through the combination of satellite gravity and altimetry data sets. The results improve upon previous efforts by incorporating a firn densification model to account for firn compaction and surface processes as well as reprocessed data sets over a slightly longer period of time. A range of different Gravity Recovery and Climate Experiment (GRACE) gravity models were evaluated and a new Ice, Cloud, and Land Elevation Satellite (ICESat) surface height trend map computed using an overlapping footprint approach. When the GIA models created from the combination approach were compared to in situ GPS ground station displacements, the vertical rates estimated showed consistently better agreement than recent conventional GIA models. The new empirically derived GIA rates suggest the presence of strong uplift in the Amundsen Sea sector in West Antarctica (WA) and the Philippi/Denman sectors, as well as subsidence in large parts of East Antarctica (EA). The total GIA-related mass change estimates for the entire Antarctic ice sheet ranged from 53 to 103 Gt yr-1, depending on the GRACE solution used, with an estimated uncertainty of ±40 Gt yr-1. Over the time frame February 2003-October 2009, the corresponding ice mass change showed an average value of -100 ± 44 Gt yr-1 (EA: 5 ± 38, WA: -105 ± 22), consistent with other recent estimates in the literature, with regional mass loss mostly concentrated in WA. The refined approach presented in this study shows the contribution that such data combinations can make towards improving estimates of present-day GIA and ice mass change, particularly with respect to determining more reliable uncertainties.

  12. A synthesis of the Antarctic surface mass balance during the last 800 yr

    Directory of Open Access Journals (Sweden)

    M. Frezzotti

    2013-02-01

    Full Text Available Global climate models suggest that Antarctic snowfall should increase in a warming climate and mitigate rises in the sea level. Several processes affect surface mass balance (SMB, introducing large uncertainties in past, present and future ice sheet mass balance. To provide an extended perspective on the past SMB of Antarctica, we used 67 firn/ice core records to reconstruct the temporal variability in the SMB over the past 800 yr and, in greater detail, over the last 200 yr.

    Our SMB reconstructions indicate that the SMB changes over most of Antarctica are statistically negligible and that the current SMB is not exceptionally high compared to the last 800 yr. High-accumulation periods have occurred in the past, specifically during the 1370s and 1610s. However, a clear increase in accumulation of more than 10% has occurred in high SMB coastal regions and over the highest part of the East Antarctic ice divide since the 1960s. To explain the differences in behaviour between the coastal/ice divide sites and the rest of Antarctica, we suggest that a higher frequency of blocking anticyclones increases the precipitation at coastal sites, leading to the advection of moist air in the highest areas, whereas blowing snow and/or erosion have significant negative impacts on the SMB at windy sites. Eight hundred years of stacked records of the SMB mimic the total solar irradiance during the 13th and 18th centuries. The link between those two variables is probably indirect and linked to a teleconnection in atmospheric circulation that forces complex feedback between the tropical Pacific and Antarctica via the generation and propagation of a large-scale atmospheric wave train.

  13. Spurious barometric pressure acceleration in Antarctica and propagation into GRACE Antarctic mass change estimates

    Science.gov (United States)

    Kim, Byeong-Hoon; Eom, Jooyoung; Seo, Ki-Weon; Wilson, Clark R.

    2016-08-01

    Apparent acceleration in Gravity Recovery and Climate Experiment (GRACE) Antarctic ice mass time-series may reflect both ice discharge and surface mass balance contributions. However, a recent study suggests there is also contamination from errors in atmospheric pressure de-aliasing fields [European Center for Medium-Range Weather Forecast (ECMWF) operational products] used during GRACE data processing. To further examine this question, we compare GRACE atmospheric pressure de-aliasing (GAA) fields with in situ surface pressure data from coastal and inland stations. Differences between the two are likely due to GAA errors, and provide a measure of error in GRACE solutions. Time-series of differences at individual weather stations are fit to four presumed error components: annual sinusoids, a linear trend, an acceleration term and jumps at times of known ECMWF model changes. Using data from inland stations, we estimate that atmospheric pressure error causes an acceleration error of about +7.0 Gt yr-2, which is large relative to prior GRACE estimates of Antarctic ice mass acceleration in the range of -12 to -14 Gt yr-2. We also estimate apparent acceleration rates from other barometric pressure (reanalysis) fields, including ERA-Interim, MERRA and NCEP/DOE. When integrated over East Antarctica, the four mass acceleration estimates (from GAA and the three reanalysis fields) vary considerably (by ˜2-16 Gt yr-2). This shows the need for further effort to improve atmospheric mass estimates in this region of sparse in situ observations, in order to use GRACE observations to measure ice mass acceleration and related sea level change.

  14. Antarctic Pumpdown---a New Geoengineering Concept for Capturing and Storing Atmospheric Carbon Dioxide

    Science.gov (United States)

    Beget, J. E.

    2014-12-01

    Growing concentrations of carbon dioxide in the atmosphere are increasing global temperatures. This is projected to impact human society in negative ways. Multiple geoengineering approaches have been suggested that might counteract problems created by greenhouse warming, but geoengineering itself can be problematic as some proposed methods would pose environmental risks to the oceans, atmosphere, and biosphere. I propose a new approach that would remove CO2 from the atmosphere and store it in the cryosphere. Carbon dioxide would be captured by seeding the atmosphere over a designated small region of central Antarctica with monoethanolamine (MEA), a well known compound commonly used for CO2 capture in submarines and industrial processes. Monoethanolamine captures and retains carbon dioxide until it encounters water. Because MEA crystals are stable when dry, they would fall from the atmosphere just in the local area where the seeding is done, and they would be naturally buried by snowfalls and preserved in the upper parts of the East Antarctic Ice Sheet, where thawing does not occur. The carbon dioxide removed from the atmosphere by this process could reside safely in this geologic reservoir for thousands of years, based on known flow characteristic of the ice sheet. Also, carbon dioxide stored in this way could be recovered in the future by drilling into the ice sheet to the frozen storage zone. The CO2 Antarctic Pumpdown (CAP) concept could potentially be used to stabilize or reduce the amount of carbon dioxide in the atmosphere, and then to store the carbon dioxide safely and inexpensively in a stable geologic reservoir

  15. Mitochondrial Acclimation Capacities to Ocean Warming and Acidification Are Limited in the Antarctic Nototheniid Fish, Notothenia rossii and Lepidonotothen squamifrons

    OpenAIRE

    Strobel, Anneli; Graeve, Martin; Poertner, Hans O.; Mark, Felix C

    2013-01-01

    Antarctic notothenioid fish are characterized by their evolutionary adaptation to the cold, thermostable Southern Ocean, which is associated with unique physiological adaptations to withstand the cold and reduce energetic requirements but also entails limited compensation capacities to environmental change. This study compares the capacities of mitochondrial acclimation to ocean warming and acidification between the Antarctic nototheniid Notothenia rossii and the sub-Antarctic Lepidonotothen ...

  16. 78 FR 66074 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2013-11-04

    ... the Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism..., Technology, Engineering, and Mathematics) STEM educational purposes. The gathered materials would be used to create lesson plans about Antarctic Exploration that focus on science, technology, engineering...

  17. A new look at the structure of the Antarctic continent from P wave travel times and adaptively parameterized tomography

    Science.gov (United States)

    Bishop, J. A.; Hansen, S. E.

    2011-12-01

    The geologic processes shaping the Antarctic continent are widely debated. In order to evaluate candidate models for the region, tomographic images that highlight the upper mantle structure are crucial; however, existing continental-scale tomography models for Antarctica lack sufficient resolution to delineate important, diagnostic features. Most tomographic models are generated using a uniformly-spaced grid over the entire study area, which can result in reduced resolution by over-emphasizing poorly sampled areas of the model and not providing enough emphasis in areas containing pertinent small-scale structure. Alternatively, the adaptively parameterized tomography method constructs a more condensed grid spacing in areas with better seismic ray coverage, thereby allowing such regions to be better resolved, while at the same time limiting the resolution of features in areas with less seismic coverage. By generating such a model for Antarctica, this approach allows candidate geologic models to be more critically assessed, resulting in a better understanding not only of Antarctic geodynamic processes but also of important processes on a global scale. In addition, the resulting tomographic model will impact thermal lithospheric estimates used to characterize ice sheet dynamics and climate-ice models, which are important in understanding the cooling history of the continent. Preliminary results will be shown.

  18. Law 16.518 Antarctic Treaty: approve the protocols about Environment protection and annex s

    International Nuclear Information System (INIS)

    The treaty Antarctic in their appendix C in its articles is about the elimination of residuals by means of its removal of the area of having Treated Antarctic among them radioactive materials, planning of the wastes, communication treatment and exam of the plans of treatment of wastes, treatment proceeding prevention of sea contamination ,discharge of hydrocarbons petroliferous, discharge of liquid noxious substances

  19. Living resources of Antarctic India's contribution to exploration and future plans for exploration

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.

    stream_size 7 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_459.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_459.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  20. 78 FR 51213 - Notice of Permits Issued Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2013-08-20

    ... Antarctic Science, Tourism and Conservation Act of 1996, (16 U.S.C 2401 et seq.), and Article 7 of the... Antarctic Science, Tourism and Conservation Act of 1996, (16 U.S.C 2401 et seq). SUMMARY: On March 31,...

  1. Escherichia coli out in the cold: Dissemination of human-derived bacteria into the Antarctic microbiome.

    Science.gov (United States)

    Power, Michelle L; Samuel, Angelingifta; Smith, James J; Stark, Jonathon S; Gillings, Michael R; Gordon, David M

    2016-08-01

    Discharge of untreated sewage into Antarctic environments presents a risk of introducing non-native microorganisms, but until now, adverse consequences have not been conclusively identified. Here we show that sewage disposal introduces human derived Escherichia coli carrying mobile genetic elements and virulence traits with the potential to affect the diversity and evolution of native Antarctic microbial communities. We compared E. coli recovered from environmental and animal sources in Antarctica to a reference collection of E. coli from humans and non-Antarctic animals. The distribution of phylogenetic groups and frequency of 11 virulence factors amongst the Antarctic isolates were characteristic of E. coli strains more commonly associated with humans. The rapidly emerging E. coli ST131 and ST95 clones were found amongst the Antarctic isolates, and ST95 was the predominant E. coli recovered from Weddell seals. Class 1 integrons were found in 15% of the Antarctic E. coli with 4 of 5 identified gene cassette arrays containing antibiotic resistance genes matching those common in clinical contexts. Disposing untreated sewage into the Antarctic environment does disseminate non-native microorganisms, but the extent of this impact and implications for Antarctic ecosystem health are, as yet, poorly understood. PMID:27179324

  2. Standing crop and growth rates of net phytoplankton and nanoplankton in Antarctic waters

    Digital Repository Service at National Institute of Oceanography (India)

    Goes, J.I.; Fondekar, S.P.; Parulekar, A.H.

    stream_size 16 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_419.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_419.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  3. UPREGULATION OF STRESS ASSOCIATED GENES IN THE OVERWINTERING STAGES OF THE ANTARCTIC MIDGE, BELGICA ANTARCTICA

    Science.gov (United States)

    We have investigated the molecular basis of stress resistance in the midge Belgica antarctica, the largest known free-living animal to adapt to a terrestrial existence on the Antarctic continent. Prevalent in specific locations throughout the Antarctic peninsula, this insect has a two-year life cyc...

  4. Response of the Antarctic stratosphere to warm pool El Niño Events in the GEOS CCM

    Directory of Open Access Journals (Sweden)

    M. M. Hurwitz

    2011-03-01

    Full Text Available A new formulation of the Goddard Earth Observing System Chemistry-Climate Model, Version 2 (GEOS V2 CCM, with an improved general circulation model and an internally generated quasi-biennial oscillation (QBO, is used to investigate the response of the Antarctic stratosphere to (1 warm pool El Niño (WPEN events and (2 the sensitivity of this response to the phase of the QBO. Two 50-yr time-slice simulations are forced by repeating annual cycles of sea surface temperatures and sea ice concentrations composited from observed WPEN and neutral ENSO (ENSON events. In these simulations, greenhouse gas and ozone-depleting substance concentrations represent the present-day climate. The modelled responses to WPEN, and to the phase of the QBO during WPEN, are compared with NASA's Modern Era Retrospective-Analysis for Research and Applications (MERRA reanalysis.

    WPEN events enhance poleward planetary wave activity in the central South Pacific during austral spring, leading to relative warming of the Antarctic lower stratosphere in November/December. During the easterly phase of the QBO (QBO-E, the GEOS V2 CCM reproduces the observed 3–5 K warming of the polar region at 50 hPa, in the WPEN simulation relative to ENSON.

    In the recent past, the response to WPEN events was sensitive to the phase of the QBO: the enhancement in planetary wave driving and the lower stratospheric warming signal were mainly associated with WPEN events coincident with QBO-E. In the GEOS V2 CCM, however, the Antarctic response to WPEN events is insensitive to the phase of the QBO: the modelled response is always easterly QBO-like. OLR, streamfunction and Rossby wave energy diagnostics are used to show that the modelled QBO does not extend far enough into the lower stratosphere and upper troposphere to modulate convection and thus planetary wave activity in the south central Pacific.

  5. Synchronicity between ice retreat and phytoplankton bloom in circum-Antarctic polynyas

    Science.gov (United States)

    Li, Yun; Ji, Rubao; Jenouvrier, Stephanie; Jin, Meibing; Stroeve, Julienne

    2016-03-01

    Phytoplankton in Antarctic coastal polynyas has a temporally short yet spatially variant growth window constrained by ice cover and day length. Using 18-year satellite measurements (1997-2015) of sea ice and chlorophyll concentrations, we assessed the synchronicity between the spring phytoplankton bloom and light availability, taking into account the ice cover and the incident solar irradiance, for 50 circum-Antarctic coastal polynyas. The synchronicity was strong (i.e., earlier ice-adjusted light onset leads to earlier bloom and vice versa) in most of the western Antarctic polynyas but weak in a majority of the eastern Antarctic polynyas. The west-east asymmetry is related to sea ice production rate: the formation of many eastern Antarctic polynyas is associated with strong katabatic wind and high sea ice production rate, leading to stronger water column mixing that could damp phytoplankton blooms and weaken the synchronicity.

  6. Climate-dependent evolution of Antarctic ectotherms: An integrative analysis

    Science.gov (United States)

    Pörtner, Hans O.

    2006-04-01

    The paper explores the climate-dependent evolution of marine Antarctic fauna and tries to identify key mechanisms involved as well as the driving forces that have caused the physiological and life history characteristics observed today. In an integrative approach it uses the recent concept of oxygen and capacity limited thermal tolerance to identify potential links between molecular, cellular, whole-organism, and ecological characteristics of marine animal life in the Antarctic. As a generalized pattern, minimization of baseline energy costs, for the sake of maximized growth in the cold, appears as one over-arching principle shaping the evolution and functioning of Antarctic marine ectotherms. This conclusion is supported by recent comparisons with (sub-) Arctic ectotherms, where elevated levels of energy turnover result at unstable, including cold temperatures, and are related to wide windows of thermal tolerance and associated metabolic features. At biochemical levels, metabolic regulation at low temperatures in general, is supported by the cold compensation of enzyme kinetic parameters like substrate affinities and turnover numbers, through minute structural modifications of the enzyme molecule. These involve a shift in protein folding, sometimes supported by the replacement of individual amino acids. The hypothesis is developed that efficient metabolic regulation at low rates in Antarctic marine stenotherms occurs through high mitochondrial densities at low capacities and possibly enhanced levels of Arrhenius activation energies or activation enthalpies. This contrasts the more costly patterns of metabolic regulation at elevated rates in cold-adapted eurytherms. Energy savings in Antarctic ectotherms, largely exemplified in fish, typically involve low-cost, diffusive oxygen distribution due to high density of lipid membranes, loss of haemoglobin, myoglobin and the heat shock response, reduced anaerobic capacity, large myocytes with low ion exchange activities

  7. Constraining East Antarctic mass trends using a Bayesian inference approach

    Science.gov (United States)

    Martin-Español, Alba; Bamber, Jonathan L.

    2016-04-01

    East Antarctica is an order of magnitude larger than its western neighbour and the Greenland ice sheet. It has the greatest potential to contribute to sea level rise of any source, including non-glacial contributors. It is, however, the most challenging ice mass to constrain because of a range of factors including the relative paucity of in-situ observations and the poor signal to noise ratio of Earth Observation data such as satellite altimetry and gravimetry. A recent study using satellite radar and laser altimetry (Zwally et al. 2015) concluded that the East Antarctic Ice Sheet (EAIS) had been accumulating mass at a rate of 136±28 Gt/yr for the period 2003-08. Here, we use a Bayesian hierarchical model, which has been tested on, and applied to, the whole of Antarctica, to investigate the impact of different assumptions regarding the origin of elevation changes of the EAIS. We combined GRACE, satellite laser and radar altimeter data and GPS measurements to solve simultaneously for surface processes (primarily surface mass balance, SMB), ice dynamics and glacio-isostatic adjustment over the period 2003-13. The hierarchical model partitions mass trends between SMB and ice dynamics based on physical principles and measures of statistical likelihood. Without imposing the division between these processes, the model apportions about a third of the mass trend to ice dynamics, +18 Gt/yr, and two thirds, +39 Gt/yr, to SMB. The total mass trend for that period for the EAIS was 57±20 Gt/yr. Over the period 2003-08, we obtain an ice dynamic trend of 12 Gt/yr and a SMB trend of 15 Gt/yr, with a total mass trend of 27 Gt/yr. We then imposed the condition that the surface mass balance is tightly constrained by the regional climate model RACMO2.3 and allowed height changes due to ice dynamics to occur in areas of low surface velocities (<10 m/yr) , such as those in the interior of East Antarctica (a similar condition as used in Zwally 2015). The model must find a solution that

  8. Multi- year Arctic and Antarctic aerosol chemical characterization

    Science.gov (United States)

    Udisti, Roberto; Becagli, Silvia; Caiazzo, Laura; Calzolai, Giulia; Cappelletti, David; Giardi, Fabio; Grotti, Marco; Malandrino, Mery; Nava, Silvia; Severi, Mirko; Traversi, Rita

    2016-04-01

    Long term measurements of aerosol chemical composition in polar region are particularly relevant to investigate potential climatic effects of atmospheric components arising from both natural and anthropogenic emissions. In order to improve our knowledge on the atmospheric load and chemical composition of polar aerosol, several measurements and sampling campaigns were carried out both in Antarctica and in the Arctic since 2005.The main results are here reported. As regard as Antarctica, a continuous all-year-round sampling of size-segregated aerosol was carried from 2005 to 2013 at Dome C (East Antarctica; 75° 60' S, 123° 200' E, 3220 m a.s.l. and 1100 km away from the nearest coast). Aerosol was collected by PM10 and PM2.5 samplers and by multi-stage impactors (Dekati 4-stage impactor). Chemical analysis was carried out by Ion Chromatography (ions composition) and ICP-MS (trace metals). Sea spray showed a sharp seasonal pattern, with winter (Apr-Nov) concentrations about ten times larger than summer (Dec-Mar). Besides, in winter, sea spray particles are mainly sub micrometric, while the summer size-mode is around 1-2 um. Meteorological analysis and air mass back trajectory reconstructions allowed the identification of two major air mass pathways: micrometric fractions for transport from the closer Indian-Pacific sector, and sub-micrometric particles for longer trajectories over the Antarctic Plateau. The markers of oceanic biogenic emission (methanesulfonic acid - MSA, and non-sea-salt sulphate) exhibit a seasonal cycle with summer maxima (Nov-Mar). Their size distributions show two modes (0.4- 0.7 um and 1.1-2.1 um) in early summer and just one sub-micrometric mode in full summer. The two modes are related to different transport pathways. In early summer, air masses came primarily from the Indian Ocean and spent a long time over the continent. The transport of sulphur compounds is related to sea spray aerosols and the resulting condensation of H2SO4 and MSA over

  9. Sediment fluxes of an Antarctic palaeo-ice stream system

    Science.gov (United States)

    Hogan, Kelly; Larter, Robert; Smith, James; Hillenbrand, Claus-Dieter

    2016-04-01

    New marine-geophysical data (multibeam bathymetry, high-resolution acoustic profiles) acquired in 2014 have been integrated with heritage multichannel seismic-reflection and deep-tow boomer profiles from Anvers-Hugo Trough, western Antarctic Peninsula. From these datasets we have identified seismic facies relating to ice-stream advance and flow, ice-stream retreat, and post-glacial sedimentation processes. We identify multiple subglacial seismic units forming MSGL and other streamlined landforms at a variety of size scales. This may be indicative of multiple generations of ice-flow through the confluent ice-stream system. We also calculate the sediment volumes of a series of grounding-zone wedges (GZWs) located on the outer and mid-shelf that were produced during several stillstands in the trough as the grounded ice margin retreated through the system during deglaciation around c. 15-13 ka (from published core chronologies). Based on these volumes we consider the likely rates of subglacial sediment delivery by the Anvers Trough palaeo-ice stream and compare these to inferred flux rates from other palaeo- and modern Antarctic ice streams. In addition, we map the post-glacial glacimarine sediment package in the trough. Large mapped sediment thicknesses of this unit across the trough are consistent with high post-glacial sediment accumulation rates reported from cores acquired in the Anvers-Hugo Trough system. Previous authors have attributed this to exceptionally high primary productivity in a calving-bay re-entrant settings produced as ice retreated across the shelf on this part of the Antarctic margin.

  10. Environmental impact on the polar regions

    International Nuclear Information System (INIS)

    The remote and frigid polar regions are no longer isolated from the activities, pollutants, and controversies that bedevil their more temperate neighbors, say three researchers at the University of Alaska in Fairbanks. For example, Daniel A. Jaffe, Elizabeth Leighton, and Mark A. Tumeo point to traces of DDT, PCBs, and heavy metals that routinely turn up in arctic marine mammals and to the ozone hole over the Antarctic. While similar in environmental makeup, the arctic and Antarctic are poles apart in their political structure and, thus, in their environmental exposure, the researchers note. The Antarctic is managed under a long-standing international treaty, while the arctic is sovereign territory to eight separate nations. The international treaty sets aside the Antarctic for peaceful scientific research within strict environmental boundaries. It bans both military activity and minerals extraction-the two activities that have caused the most damage in the arctic. The main threats to Antarctica's environment come from the intrusion of major scientific research operations and the growing tourism industry. On the other hand, the arctic suffered from the massive Cold War military buildup by both the United States and the former Soviet Union. The environmental residue from that buildup is only now being revealed, the authors say. Major oil and gas drilling and coal and metal-ore mining also have taken a huge environmental toll, they add

  11. Parameter Estimations of Dynamic Energy Budget (DEB Model over the Life History of a Key Antarctic Species: The Antarctic Sea Star Odontaster validus Koehler, 1906.

    Directory of Open Access Journals (Sweden)

    Antonio Agüera

    Full Text Available Marine organisms in Antarctica are adapted to an extreme ecosystem including extremely stable temperatures and strong seasonality due to changes in day length. It is now largely accepted that Southern Ocean organisms are particularly vulnerable to global warming with some regions already being challenged by a rapid increase of temperature. Climate change affects both the physical and biotic components of marine ecosystems and will have an impact on the distribution and population dynamics of Antarctic marine organisms. To predict and assess the effect of climate change on marine ecosystems a more comprehensive knowledge of the life history and physiology of key species is urgently needed. In this study we estimate the Dynamic Energy Budget (DEB model parameters for key benthic Antarctic species the sea star Odontaster validus using available information from literature and experiments. The DEB theory is unique in capturing the metabolic processes of an organism through its entire life cycle as a function of temperature and food availability. The DEB model allows for the inclusion of the different life history stages, and thus, becomes a tool that can be used to model lifetime feeding, growth, reproduction, and their responses to changes in biotic and abiotic conditions. The DEB model presented here includes the estimation of reproduction handling rules for the development of simultaneous oocyte cohorts within the gonad. Additionally it links the DEB model reserves to the pyloric caeca an organ whose function has long been ascribed to energy storage. Model parameters described a slowed down metabolism of long living animals that mature slowly. O. validus has a large reserve that-matching low maintenance costs- allow withstanding long periods of starvation. Gonad development is continuous and individual cohorts developed within the gonads grow in biomass following a power function of the age of the cohort. The DEB model developed here for O

  12. Parameter Estimations of Dynamic Energy Budget (DEB) Model over the Life History of a Key Antarctic Species: The Antarctic Sea Star Odontaster validus Koehler, 1906.

    Science.gov (United States)

    Agüera, Antonio; Collard, Marie; Jossart, Quentin; Moreau, Camille; Danis, Bruno

    2015-01-01

    Marine organisms in Antarctica are adapted to an extreme ecosystem including extremely stable temperatures and strong seasonality due to changes in day length. It is now largely accepted that Southern Ocean organisms are particularly vulnerable to global warming with some regions already being challenged by a rapid increase of temperature. Climate change affects both the physical and biotic components of marine ecosystems and will have an impact on the distribution and population dynamics of Antarctic marine organisms. To predict and assess the effect of climate change on marine ecosystems a more comprehensive knowledge of the life history and physiology of key species is urgently needed. In this study we estimate the Dynamic Energy Budget (DEB) model parameters for key benthic Antarctic species the sea star Odontaster validus using available information from literature and experiments. The DEB theory is unique in capturing the metabolic processes of an organism through its entire life cycle as a function of temperature and food availability. The DEB model allows for the inclusion of the different life history stages, and thus, becomes a tool that can be used to model lifetime feeding, growth, reproduction, and their responses to changes in biotic and abiotic conditions. The DEB model presented here includes the estimation of reproduction handling rules for the development of simultaneous oocyte cohorts within the gonad. Additionally it links the DEB model reserves to the pyloric caeca an organ whose function has long been ascribed to energy storage. Model parameters described a slowed down metabolism of long living animals that mature slowly. O. validus has a large reserve that-matching low maintenance costs- allow withstanding long periods of starvation. Gonad development is continuous and individual cohorts developed within the gonads grow in biomass following a power function of the age of the cohort. The DEB model developed here for O. validus allowed us to

  13. Prospects for surviving climate change in Antarctic aquatic species

    OpenAIRE

    Peck Lloyd S

    2005-01-01

    Abstract Maritime Antarctic freshwater habitats are amongst the fastest changing environments on Earth. Temperatures have risen around 1°C and ice cover has dramatically decreased in 15 years. Few animal species inhabit these sites, but the fairy shrimp Branchinecta gaini typifies those that do. This species survives up to 25°C daily temperature fluctuations in summer and passes winter as eggs at temperatures down to -25°C. Its annual temperature envelope is, therefore around 50°C. This is ty...

  14. Temperature-dependent enthalpy of oxygenation in Antarctic fish hemoglobins

    DEFF Research Database (Denmark)

    Fago, A.; Wells, R.M.G.; Weber, Roy E.

    1997-01-01

    (logP(50) vs 1/T) of D. mawsoni hemoglobin indicates that the enthalpy of oxygenation (slope of the plot) is temperature dependent and that at high temperatures oxygen-binding becomes less exothermic. Nearly linear relationships were found in the hemoglobins of the other two species. The data were...... literature data for the enthalpy of oxygenation in Antarctic fish hemoglobins derives from the use of the nonintegrated (linearized) form of the van't Hoff equation over different temperature ranges. The general assumption that a low heat of oxygenation in hemoglobins from polar animals represents an...

  15. Cryptococcus friedmannii, a new species of yeast from the Antarctic

    Science.gov (United States)

    Vishniac, H. S.

    1985-01-01

    Cryptococcus friedmannii Vishniac sp. nov. from an Antarctic cryptoendolithic community is a psychrophilic basidioblastomycete characterized by cream-colored colonies of cells with smooth, layered walls, budding monopolarly, producing amylose and extracellular proteinase, utilizing nitrate and D-alanine (inter alia) as nitrogen sources and L-arabinose, arbutin, cellobiose, D-glucuronate, maltose, melezitose, salicin, soluble starch, trehalose, and D-xylose as carbon sources. This species differs from all other basidiomycetous yeasts in possessing the following combination of characters: amylose production (positive), assimilation of cellobiose (positive), D-galactose (negative), myo-inositol (negative), D-mannitol (negative), and sucrose (negative).

  16. Algal and fungal diversity in Antarctic lichens.

    Science.gov (United States)

    Park, Chae Haeng; Kim, Kyung Mo; Elvebakk, Arve; Kim, Ok-Sun; Jeong, Gajin; Hong, Soon Gyu

    2015-01-01

    The composition of lichen ecosystems except mycobiont and photobiont has not been evaluated intensively. In addition, recent studies to identify algal genotypes have raised questions about the specific relationship between mycobiont and photobiont. In the current study, we analyzed algal and fungal community structures in lichen species from King George Island, Antarctica, by pyrosequencing of eukaryotic large subunit (LSU) and algal internal transcribed spacer (ITS) domains of the nuclear rRNA gene. The sequencing results of LSU and ITS regions indicated that each lichen thallus contained diverse algal species. The major algal operational taxonomic unit (OTU) defined at a 99% similarity cutoff of LSU sequences accounted for 78.7-100% of the total algal community in each sample. In several cases, the major OTUs defined by LSU sequences were represented by two closely related OTUs defined by 98% sequence similarity of ITS domain. The results of LSU sequences indicated that lichen-associated fungi belonged to the Arthoniomycetes, Eurotiomycetes, Lecanoromycetes, Leotiomycetes, and Sordariomycetes of the Ascomycota, and Tremellomycetes and Cystobasidiomycetes of the Basidiomycota. The composition of major photobiont species and lichen-associated fungal community were mostly related to the mycobiont species. The contribution of growth forms or substrates on composition of photobiont and lichen-associated fungi was not evident. PMID:25105247

  17. Extensive lake sediment coring survey on Sub-Antarctic Indian Ocean Kerguelen Archipelago (French Austral and Antarctic Lands)

    Science.gov (United States)

    Arnaud, Fabien; Fanget, Bernard; Malet, Emmanuel; Poulenard, Jérôme; Støren, Eivind; Leloup, Anouk; Bakke, Jostein; Sabatier, Pierre

    2016-04-01

    Recent paleo-studies revealed climatic southern high latitude climate evolution patterns that are crucial to understand the global climate evolution(1,2). Among others the strength and north-south shifts of westerlies wind appeared to be a key parameter(3). However, virtually no lands are located south of the 45th South parallel between Southern Georgia (60°W) and New Zealand (170°E) precluding the establishment of paleoclimate records of past westerlies dynamics. Located around 50°S and 70°E, lost in the middle of the sub-Antarctic Indian Ocean, Kerguelen archipelago is a major, geomorphologically complex, land-mass that is covered by hundreds lakes of various sizes. It hence offers a unique opportunity to reconstruct past climate and environment dynamics in a region where virtually nothing is known about it, except the remarkable recent reconstructions based on a Lateglacial peatbog sequence(4). During the 2014-2015 austral summer, a French-Norwegian team led the very first extensive lake sediment coring survey on Kerguelen Archipelago under the umbrella of the PALAS program supported by the French Polar Institute (IPEV). Two main areas were investigated: i) the southwest of the mainland, so-called Golfe du Morbihan, where glaciers are currently absent and ii) the northernmost Kerguelen mainland peninsula so-called Loranchet, where cirque glaciers are still present. This double-target strategy aims at reconstructing various independent indirect records of precipitation (glacier advance, flood dynamics) and wind speed (marine spray chemical species, wind-borne terrigenous input) to tackle the Holocene climate variability. Despite particularly harsh climate conditions and difficult logistics matters, we were able to core 6 lake sediment sites: 5 in Golfe du Morbihan and one in Loranchet peninsula. Among them two sequences taken in the 4km-long Lake Armor using a UWITEC re-entry piston coring system by 20 and 100m water-depth (6 and 7m-long, respectively). One

  18. Directional Analysis of Sub-Antarctic Climate Change on South Georgia 1905-2009

    Science.gov (United States)

    Sakamoto Ferranti, Emma Jayne; Solera Garcia, Maria Angeles; Timmis, Roger James; Gerrard McKenna, Paul; Whyatt, James Duncan

    2010-05-01

    Directional analysis has been used to study changes in the sub-polar climate of the mountainous and glacierised sub-Antarctic island of South Georgia (54-55°S, 36-38°W). Significantly for climate change studies, South Georgia lies in the Scotia Sea between polar and temperate latitudes, and approximately 1000 km northeast and downwind of the Antarctic Peninsula - one of the fastest-warming regions on Earth (Vaughan et al., 2001). South Georgia was chosen for directional analysis because its climate is substantially advected by predominantly westerly circulations, and because it has a long (since 1905) meteorological record from King Edward Point (KEP) on its eastern side. Additional shorter records from Bird Island at the northwest tip of South Georgia allow comparison between windward (Bird Island) and leeward (KEP) climate regimes. The variation of mountain barrier heights with direction from KEP allows climate changes to be studied under different amounts of orographic influence (from ~700 m to ~2200 m). Records of glacier advance and retreat provide further independent evidence of climate change for comparison with the meteorological record. Directional climate analysis is based on a series of monthly-mean pressure fields defining the orientation and strength of synoptic-scale air-mass advection over the Scotia Sea. These fields are used to define directional climatologies for six 30° sectors with bearings from 150-180° to 300-330°; these sectors encompass 99% of recorded months since 1905. The climatologies summarise the frequencies of air masses from each sector, and the accompanying temperatures and precipitation. The 6 sectors can be broadly associated with 4 air-mass types and source regions: (i) sectors 150-210° advect cold polar maritime air that originated over the Antarctic continent before passing over the Weddell Sea, (ii) sectors 210-270° advect warmer, more stable polar maritime air from the Bellingshausen Sea/Antarctic Peninsula region

  19. Anti-inflammatory activity in selected Antarctic benthic organisms

    Directory of Open Access Journals (Sweden)

    Juan eMoles

    2014-07-01

    Full Text Available Antarctic benthos was prospected in search for anti-inflammatory activity in polar benthic invertebrates, in two different geographical areas: deep-bottoms of the Eastern Weddell Sea and shallow-waters of the South Shetland Islands. A total of 36 benthic algae and invertebrate species were selected to perform solubility tests in order to test them for anti-inflammatory activity. From these, ethanol extracts of ten species from five different phyla resulted suitable to be studied in cell macrophage cultures (RAW 264.7. Cytotoxicity (MTT method and production of inflammatory mediators (prostaglandin E2, leukotriene B4, interleukin-1 were determined at three extract concentrations (50, 125, 250 g/mL. Bioassays resulted in four different species showing anti-inflammatory activity corresponding to three sponges: Mycale (Oxymycale acerata, Isodictya erinacea, and I. toxophila; and one hemichordate: Cephalodiscus sp. These results show that Antarctic sessile invertebrates may have great value as a source of lead compounds with potential pharmaceutical applications.

  20. Snow surface microbiome on the High Antarctic Plateau (DOME C.

    Directory of Open Access Journals (Sweden)

    Luigi Michaud

    Full Text Available The cryosphere is an integral part of the global climate system and one of the major habitable ecosystems of Earth's biosphere. These permanently frozen environments harbor diverse, viable and metabolically active microbial populations that represent almost all the major phylogenetic groups. In this study, we investigated the microbial diversity in the surface snow surrounding the Concordia Research Station on the High Antarctic Plateau through a polyphasic approach, including direct prokaryotic quantification by flow cytometry and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH, and phylogenetic identification by 16S RNA gene clone library sequencing and 454 16S amplicon pyrosequencing. Although the microbial abundance was low (<10(3 cells/ml of snowmelt, concordant results were obtained with the different techniques. The microbial community was mainly composed of members of the Alpha-proteobacteria class (e.g. Kiloniellaceae and Rhodobacteraceae, which is one of the most well-represented bacterial groups in marine habitats, Bacteroidetes (e.g. Cryomorphaceae and Flavobacteriaceae and Cyanobacteria. Based on our results, polar microorganisms could not only be considered as deposited airborne particles, but as an active component of the snowpack ecology of the High Antarctic Plateau.

  1. Processing of Antarctic Meteorites at NASA/Johnson Space Center

    Science.gov (United States)

    Satterwhite, C. E.; McBridge, K. M.; Harrington, R. S.; Righter, K.

    2011-01-01

    Since the beginning of the Antarctic Search for Meteorites (ANSMET) program in 1976, over 18,000 meteorites have been processed in the Meteorite Processing Lab at Johnson Space Center in Houston, TX. The first step is to renumber the meteorites from field tag number to generic number and log all the information into the meteorite database. Initial processing involves drying the meteorites in a nitrogen glove box for 24 to 48 hours, photographing, measuring, weighing and writing an exterior description. Next step is to break the meteorite and obtain a good representative sample that will be sent to the Smithsonian institution for classification. Once all the processing is done and the meteorites have been classified, the information is published in the Antarctic meteorite newsletter. The newsletter is published twice yearly and is sent electronically to researchers around the world and is also available on line. Researchers are asked to fill out a request form. The bulk of this paper relates to the researcher's request for meteorite samples.

  2. Antarctic environmental specimen bank. A tool for chemical monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Soggia, F.; Dalla Riva, S.; Abelmoschi, M.L.; Frache, R. [Genoa Univ., Genoa (Italy). Dipt. di Chimica e Chimica Industriale

    2000-02-01

    The work illustrates the project on Antarctic Environmental Specimen Bank (BCAA), which is an integral part of the Italian project on the micropollutants chemistry (sector on chemical contamination of the Italian Antarctic Research program, PNRA), begun in 1994 when the BCAA was installed in the department of chemistry and industrial chemistry (Genoa University, Italy). Its objective underlines an emphasis on environmental chemistry and the establishment of baselines similar to the approaches followed by the other environmental specimen banks, begun at the end of Sixties with the aim of long-term storage of representative environmental specimens in order to study the presence and the evolution of dangerous substances, but focus on the chemical characterization of samples. [Italian] Il lavoro illustra le finalita' del Progetto su una Banca Campioni Ambientali Antartici (BCAA), che e' parte integrante del progetto Chmica dei microinquinannti del Settore Contaminazione chimica del Programma Nazionale di ricerche in Antartide (ONRA), nata nel 1994 presso il dipartimento di chimicia e chimica industriale dell'universita' di Genova. A differenza di altri progetti internazionali che enfatizzano gli aspetti biologici, ecologici e medici, il progetto BCAA enfatizza la chimica ambientale.

  3. Antarctic Radio Frequency Albedo and Implications for Cosmic Ray Reconstruction

    CERN Document Server

    Besson, D Z; Sullivan, M; Allison, P; Barwick, S W; Baughman, B M; Beatty, J J; Belov, K; Bevan, S; Binns, W R; Chen, C; Chen, P; Clem, J M; Connolly, A; De Marco, D; Dowkontt, P F; DuVernois, M; Goldstein, D; Gorham, P W; Grashorn, E W; Hill, B; Hoover, S; Huang, M; Israel, M H; Javaid, A; Kowalski, J; Learned, J; Liewer, K M; Matsuno, S; Mercurio, B C; Miki, C; Mottram, M; Nam, J; Naudet, C J; Nichol, R J; Palladino, K; Romero-Wolf, A; Ruckman, L; Saltzberg, D; Seckel, D; Shang, R Y; Stockham, M; Varner, G S; Vieregg, A G; Wang, Y

    2013-01-01

    From an elevation of ~38 km, the balloon-borne ANtarctic Impulsive Transient Antenna (ANITA) is designed to detect the up-coming radio frequency (RF) signal resulting from a sub-surface neutrino-nucleon collision. Although no neutrinos have been discovered thus far, ANITA is nevertheless the only experiment to self-trigger on radio frequency emissions from cosmic-ray induced atmospheric air showers. In the majority of those cases, down-coming RF signals are observed via their reflection from the Antarctic ice sheet and back up to the ANITA interferometer. Estimating the energy scale of the incident cosmic rays therefore requires an estimate of the fractional power reflected at the air-ice interface. Similarly, inferring the energy of neutrinos interacting in-ice from observations of the upwards-directed signal refracting out to ANITA also requires consideration of signal coherence across the interface. By comparing the direct Solar RF signal intensity measured with ANITA to the surface-reflected Solar signal ...

  4. Testing a Mars science outpost in the Antarctic dry valleys

    Science.gov (United States)

    Andersen, D. T.; Mckay, C. P.; Wharton, R. A.; Rummel, J. D.

    1992-01-01

    Field research conducted in the Antarctic has been providing insights about the nature of Mars in the science disciplines of exobiology and geology. Located in the McMurdo Dry Valleys of southern Victoria Land (160 deg and 164 deg E longitude and 76 deg 30 min and 78 deg 30 min S latitude), research outposts are inhabited by teams of 4-6 scientists. It is proposed that the design of these outposts be expanded to enable meaningful tests of many of the systems that will be needed for the successful conduct of exploration activities on Mars. Although there are some important differences between the environment in the Antarctic dry valleys and on Mars, the many similarities and particularly the field science activities, make the dry valleys a useful terrestrial analog to conditions on Mars. Three areas have been identified for testing at a small science outpost in the dry valleys: (1) studying human factors and physiology in an isolated environment; (2) testing emerging technologies (e.g. innovative power management systems, advanced life support facilities including partial bioregenerative life support systems for water recycling and food growth, telerobotics, etc.); and (3) conducting basic scientific research that will enhance understanding of Mars while contributing to the planning for human exploration. It is suggested that an important early result of a Mars habitat program will be the experience gained by interfacing humans and their supporting technology in a remote and stressful environment.

  5. The Southern Ocean and South Pacific Region

    OpenAIRE

    Kelleher, K.; Warnau, Michel; Failler, Pierre; Pecl, Gretta; Turley, Carol; Boeuf, Gilles; Laffoley, Dan; Parker, Laura; Gurney, Leigh

    2012-01-01

    The Region comprises three sub-regions (FAO Statistical Areas) with very different characteristics. The South Pacific includes the vast and virtually unpopulated Southern Ocean surrounding the Antarctic. It has the world’s largest fisheries off Peru and Chile and some of the world’s best managed fisheries in Australia and New Zealand. The Region has over 27% of the world’s ocean area and over 98% of the Region’s total area of 91 million km2 is ‘open ocean’. The Region contains less than 5% of...

  6. Environmental radioactivity at the Peruvian Scientific Station 'Machu Picchu'. Cs-137, Ra-226, Be-7 and K-40 concentrations in antarctic samples by gamma spectrometry

    International Nuclear Information System (INIS)

    In order to continue with the Research Program in Environmental Radioactivity in the Antarctic Region initiated in 1996, the Peruvian Institute of Nuclear Energy (IPEN) participated in the 11th Scientific Expedition to Antarctica (ANTAR XI) on 2000. The main objective of this study is to evaluate environmental components for achieving a baseline study related to artificial and natural radioactivity level. For this purpose, samples of brown macro-algae (phaeophyta), lichen, moss, gramineous, soil, marine sediment, sea water and air were collected in the surrounding area of the Machu Picchu Scientific Station. The physical, radiochemical treatment and radiometric assays of the samples were done in the Environmental Control Department of the 'RACSO' Nuclear Center. The presence of anthropogenic radionuclide Cs-17, in some antarctic environmental components, confirms that this element was dispersed globally after the nuclear testing carried out in other latitudes. The environmental radiological impact in the antarctic ecosystem has been minimum due to the low levels of found radioactivity. In general, lichens seem to accumulate more Cs-137 than other biological components

  7. Thermoluminescence survey of 12 meteorites collected by the European 1988 Antarctic meteorite expedition to Allan Hills and the importance of acid washing for thermoluminescence sensitivity measurements

    Science.gov (United States)

    Benoit, P. H.; Sears, H.; Sears, D. W. G.

    1991-01-01

    Natural and induced thermoluminescence (TL) data are reported for 12 meteorites recovered from the Allan Hills region of Antarctica by the European field party during the 1988/1989 field season. The samples include one with extremely high natural TL, ALH88035, suggestive of exposure to unusually high radiation doses (i.e., low degrees of shielding), and one, ALH88034, whose low natural TL suggests reheating within the last 100,000 years. The remainder have natural TL values suggestive of terrestrial ages similar to those of other meteorites from Allan Hills. ALH88015 (L6) has induced TL data suggestive of intense shock. TL sensitivities of these meteorites are generally lower than observed falls of their petrologic types, as is also observed for Antarctic meteorites in general. Acid-washing experiments indicate that this is solely the result of terrestrial weathering rather than a nonterrestrial Antarctic-non-Antarctic difference. However, other TL parameters, such as natural TL and induced peak temperature-width, are unchanged by acid washing and are sensitive indicators of a meteorite's metamorphic and recent radiation history.

  8. Depletion of stratospheric ozone over the Antarctic and Arctic: Responses of plants of polar terrestrial ecosystems to enhanced UV-B, an overview

    Energy Technology Data Exchange (ETDEWEB)

    Rozema, Jelte [Department of Systems Ecology, Institute of Ecological Science, Climate Centre, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam (Netherlands)]. E-mail: jelte.rozema@ecology.falw.vu.nl; Boelen, Peter [Department of Systems Ecology, Institute of Ecological Science, Climate Centre, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam (Netherlands); Blokker, Peter [Department of Systems Ecology, Institute of Ecological Science, Climate Centre, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam (Netherlands)

    2005-10-15

    Depletion of stratospheric ozone over the Antarctic has been re-occurring yearly since 1974, leading to enhanced UV-B radiation. Arctic ozone depletion has been observed since 1990. Ozone recovery has been predicted by 2050, but no signs of recovery occur. Here we review responses of polar plants to experimentally varied UV-B through supplementation or exclusion. In supplementation studies comparing ambient and above ambient UV-B, no effect on growth occurred. UV-B-induced DNA damage, as measured in polar bryophytes, is repaired overnight by photoreactivation. With UV exclusion, growth at near ambient may be less than at below ambient UV-B levels, which relates to the UV response curve of polar plants. UV-B screening foils also alter PAR, humidity, and temperature and interactions of UV with environmental factors may occur. Plant phenolics induced by solar UV-B, as in pollen, spores and lignin, may serve as a climate proxy for past UV. Since the Antarctic and Arctic terrestrial ecosystems differ essentially (e.g. higher species diversity and more trophic interactions in the Arctic), generalization of polar plant responses to UV-B needs caution. - Polar plant responses to UV-B may be different in the Arctic than Antarctic regions.

  9. Depletion of stratospheric ozone over the Antarctic and Arctic: Responses of plants of polar terrestrial ecosystems to enhanced UV-B, an overview

    International Nuclear Information System (INIS)

    Depletion of stratospheric ozone over the Antarctic has been re-occurring yearly since 1974, leading to enhanced UV-B radiation. Arctic ozone depletion has been observed since 1990. Ozone recovery has been predicted by 2050, but no signs of recovery occur. Here we review responses of polar plants to experimentally varied UV-B through supplementation or exclusion. In supplementation studies comparing ambient and above ambient UV-B, no effect on growth occurred. UV-B-induced DNA damage, as measured in polar bryophytes, is repaired overnight by photoreactivation. With UV exclusion, growth at near ambient may be less than at below ambient UV-B levels, which relates to the UV response curve of polar plants. UV-B screening foils also alter PAR, humidity, and temperature and interactions of UV with environmental factors may occur. Plant phenolics induced by solar UV-B, as in pollen, spores and lignin, may serve as a climate proxy for past UV. Since the Antarctic and Arctic terrestrial ecosystems differ essentially (e.g. higher species diversity and more trophic interactions in the Arctic), generalization of polar plant responses to UV-B needs caution. - Polar plant responses to UV-B may be different in the Arctic than Antarctic regions

  10. The Marine Record of Holocene Deglaciation and Paleoclimate Change, Antarctic Peninsula

    Science.gov (United States)

    Minzoni, R. L.; Anderson, J. B.; Kirshner, A. E.; Wellner, J. S.; Fernandez-Vasquez, R. A.

    2010-12-01

    The Antarctic Peninsula Ice Cap (APIC) has undergone significant retreat since the Last Glacial Maximum (LGM). Several recent studies, including those of Lallemand Fjord (Shevenell, et al., 1996), Palmer Deep (Domack, et al., 2001), Bransfield Basin (Heroy, et al., 2008), Firth of Tay (Michalchuck, et al., 2009), Maxwell Bay (Milliken, et al., 2009), and Neny Fjord (Allen, et al., 2010), have applied multiple proxies to reconstruct glacial history from sediment cores. The regional trend of post-LGM retreat from marine and onshore records (e.g. Hjort et al., 1997; Ingolfsson et al., 1998) is characterized by deglaciation of the outer and mid-shelf areas mainly before 12 ka, with significant landward steps at ~14 and 11 ka that were most likely caused by rapid sea-level rise (Heroy and Anderson, 2007). This was followed by highly diachronous retreat from the rugged inner-shelf and inland areas after ~10 ka. This marks the demise of the Antarctic Peninsula Ice Sheet. Subsequently, the glacial systems became more isolated, and factors such as latitudinal climate variability, orographic effects, oceanographic effects, the size and altitude of glacial drainage basins, as well as bathymetry of individual bays and fjords, became more influential on glacial dynamics. For example, Firth of Tay, the northern-most fjord on the eastern side of Antarctic Peninsula (AP), became ice-free ~9 ka, but Herbert Sound, just to the south, was not ice-free until ~7.4 ka. On the western side of AP, however, Maxwell Bay, located in the South Shetland Islands just north of the APIC, was free of grounded ice ~14 ka, whereas Marguerite Bay, on the southwestern-most edge of the APIC, experienced rapid grounding line and ice shelf retreat ~9 ka. These records suggest a north to south component in the timing of retreat. The lag in retreat from west to east APIC indicates that a strong orographic effect insulated the eastern AP, but also implies that other influencing factors such as oceanographic

  11. A study on the Antarctic circumpolar wave mode-A coexistence system of standing and traveling wave

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The Antarctic circumpolar wave (ACW) has become a focus of the air-sea coupled Southern Ocean study since 1996, when it was discovered as an air-sea coupled interannual signal propagating eastward in the region of the Antarctic Circumpolar Current (ACC). In order to analyze the mechanism of discontinuity along the latitudinal propagation, a new idea that ACW is a system with a traveling wave in the Southern Pacific and Atlantic Ocean and with a concurrent standing wave in the southern Indian Ocean is proposed in this paper. Based on the ideal wave principle, the average wave parameters of ACW is achieved using a non-linear approximation method, by which we find that the standing part and the traveling part possess similar radius frequency, proving their belonging to an integral system. We also give the latitudinal distribution of wave speed with which we could tell the reason for steady propagation during the same period. The spatial distribution of the propagation reveals complex process with variant spatial and temporal scales-The ENSO scale oscillation greatly impacts on the traveling process, while the result at the south of Australia indicates little connection between the Indian Ocean and the Pacific, which may be blocked by the vibration at the west of the Pacific. The advective effect of ACC on the propagation process should be examined clearly through dynamical method.

  12. Response of the Southern Ocean dynamics to the changes in the Antarctic glacial runoff and icebergs discharge

    Science.gov (United States)

    Aksenov, Yevgeny; Nurser, George; Bacon, Sheldon; Rye, Craig; Megann, Alex; Kjellsson, Joakim; Holland, Paul; Ridley, Jeff; Coward, Andrew; Marshall, Gareth; Marsh, Bob; Mathiot, Pierre

    2016-04-01

    This study examines how changes in the freshwater discharge from the Antarctic (liquid runoff and icebergs) affect stratification and ocean circulation in the Southern Ocean. The changes in the ocean circulation could potentially modify transports of the warm subsurface waters onto the continental shelves and increase ice sheet melting. We investigate impacts of the increased freshwater discharge in the 1990s-2000s on the subsurface waters in the Southern Ocean in the NEMO 1° global sea ice-ocean model. In the simulations the warming signal is largely circum-Antarctic, with "hot spots" in the Bellingshausen-Amundsen and Ross seas. The warming of the subsurface waters in the Bellingshausen-Amundsen Sea exceeds 0.5°C/decade. Differences in spreading of the liquid freshwater and icebergs in the Southern Ocean are investigated. Hindcasts and forward projections with the eddy-admitting global NEMO 1/4° model are diagnosed to examine regional trends in the ocean and sea ice states and to attribute these to the changes in the freshwater forcing and wind. The study contributes to the "Poles Apart" research project and is funded by the Natural Environment Research Council UK.

  13. Antarctic glaciation caused ocean circulation changes at the Eocene-Oligocene transition.

    Science.gov (United States)

    Goldner, A; Herold, N; Huber, M

    2014-07-31

    Two main hypotheses compete to explain global cooling and the abrupt growth of the Antarctic ice sheet across the Eocene-Oligocene transition about 34 million years ago: thermal isolation of Antarctica due to southern ocean gateway opening, and declining atmospheric CO2 (refs 5, 6). Increases in ocean thermal stratification and circulation in proxies across the Eocene-Oligocene transition have been interpreted as a unique signature of gateway opening, but at present both mechanisms remain possible. Here, using a coupled ocean-atmosphere model, we show that the rise of Antarctic glaciation, rather than altered palaeogeography, is best able to explain the observed oceanographic changes. We find that growth of the Antarctic ice sheet caused enhanced northward transport of Antarctic intermediate water and invigorated the formation of Antarctic bottom water, fundamentally reorganizing ocean circulation. Conversely, gateway openings had much less impact on ocean thermal stratification and circulation. Our results support available evidence that CO2 drawdown--not gateway opening--caused Antarctic ice sheet growth, and further show that these feedbacks in turn altered ocean circulation. The precise timing and rate of glaciation, and thus its impacts on ocean circulation, reflect the balance between potentially positive feedbacks (increases in sea ice extent and enhanced primary productivity) and negative feedbacks (stronger southward heat transport and localized high-latitude warming). The Antarctic ice sheet had a complex, dynamic role in ocean circulation and heat fluxes during its initiation, and these processes are likely to operate in the future. PMID:25079555

  14. Total gaseous mercury along a transect from coastal to central Antarctic: Spatial and diurnal variations.

    Science.gov (United States)

    Wang, Jiancheng; Zhang, Lulu; Xie, Zhouqing

    2016-11-01

    Total gaseous mercury (TGM) in the atmospheric boundary layer was investigated along a transect from coastal (Zhongshan Station; 69°22'25″S, 76°22'14″E) to central (Kunlun Station; 80°25'2″S, 77°6'47″E) Antarctic from December 16, 2012 to February 6, 2013. TGM varied considerably from 0.32 to 2.34ngm(-3) with a mean value of 0.91ngm(-3). Spatially, relatively high values occurred near the coastal region and on the central plateau with altitude higher than 3000m above sea level. This distribution pattern cannot be accounted for simply by the influence of mercury emission from the ocean. Changes in TGM were also found to be related to the topography. TGM was higher in the inland flat region (290-800km from the coast) than in the inland transition zones with steep slopes (800-1000km from the coast). Temporally, diurnal cycling of TGM was clearly observed at Kunlun Station, with the lowest value occurring typically at midnight, and the peak value at midday. This diurnal pattern was attributed to the reemission of gaseous elemental mercury (GEM) from the snow pack, the oxidization of GEM and convective mixing. PMID:27318733

  15. First results from imaging riometer installed at Indian Antarctic station Maitri

    Indian Academy of Sciences (India)

    Jayanta K Behera; A K Sinha; Anand K Singh; Rahul Rawat; Geeta Vichare; Ajay Dhar; B M Pathan; K U Nair; C Selvaraj; P Elango

    2014-04-01

    Cosmic noise absorption (CNA) measurred by imaging riometer, is an excellent tool to passively study the high latitude D-region ionospheric conditions and dynamics. An imaging riometer has been installed at Indian Antarctic station Maitri (geographic 70.75°S, 11.75°E; corrected geomagnetic 63.11°S, 53.59°E) in February 2010. This is the first paper using the imaging riometer data from Maitri. The present paper introduces the details of this facility, including its instrumentation, related CNA theory and its applications. Sidereal shift of around 2 hours in the diurnal pattern validates the data obtained from the newly installed instrument. Moreover, the strength of cosmic noise signal on quiet days also varies with months. This is apparently due to solar ionization of D-region ionosphere causing enhanced electron density where collision frequency is already high. The main objective of installing the imaging riometer at Maitri is to study magneotspheric–ionospheric coupling during substorm processes. In the current study, we present two typical examples of disturbed time CNA associated with storm-time and non-storm time substorm. Results reveal that CNA is more pronounced during storm-time substorm as compared to nonstorm-time substorm. The level of CNA strongly depends upon the strengthening of convectional electric field and the duration of southward turning of interplanetary magnetic field before the substorm onset.

  16. Antarctic Super Heroes: Using a Graphic Novel to Teach Students About Polar Science. (Invited)

    Science.gov (United States)

    Lougheed, V.; Palsole, S.; Rojas, C.; Tweedie, C. E.

    2009-12-01

    The University of Texas at El Paso received an IPY grant from the US National Science Foundation to take undergraduate and graduate students, as well as teachers, to Antarctica over winter break 2007. The program, called IPY-ROAM (International Polar Year - Research and Educational Experiences in Antarctica for Minorities) aimed to increase the number of underrepresented minorities in the sciences, and increase public awareness about the polar regions. Education and outreach activities have been designed to teach people of all ages about polar science. For example, an interactive museum exhibit was designed to describe how the polar regions are being affected by climate change, and how individuals can make a difference. Our latest outreach strategy involves taking the large amount of educational materials collected for the museum display and making it available to a broader audience. We have created a graphic novel where the story of the ROAM Antarctic trip and existing educational materials are communicated using a combination of comic strips, fact sheets, and classroom activities. Photographic images from the ROAM trip were digitized and converted to a comic strip format. These images were combined with text from film footage collected by a documentary film, as well as personal anecdotes, to convey the successes of the program and the primary messages participants wanted to share with the public. The graphic novel will be made available to local school groups and online, at our website: www.ipyroam.org.

  17. Deep Radiostratigraphy of the East Antarctic Plateau: Connecting the Dome C and Vostok Ice Core Sites

    Science.gov (United States)

    Cavitte, Marie G. P.; Blankenship, Donald D.; Young, Duncan A.; Schroeder, Dustin M.; Parrenin, Frederic; Lemeur, Emmanuel; Macgregor, Joseph A.; Siegert, Martin J.

    2016-01-01

    Several airborne radar-sounding surveys are used to trace internal reflections around the European Project for Ice Coring in Antarctica Dome C and Vostok ice core sites. Thirteen reflections, spanning the last two glacial cycles, are traced within 200 km of Dome C, a promising region for million-year-old ice, using the University of Texas Institute for Geophysics High-Capacity Radar Sounder. This provides a dated stratigraphy to 2318 m depth at Dome C. Reflection age uncertainties are calculated from the radar range precision and signal-to-noise ratio of the internal reflections. The radar stratigraphy matches well with the Multichannel Coherent Radar Depth Sounder (MCoRDS) radar stratigraphy obtained independently. We show that radar sounding enables the extension of ice core ages through the ice sheet with an additional radar-related age uncertainty of approximately 1/3-1/2 that of the ice cores. Reflections are extended along the Byrd-Totten Glacier divide, using University of Texas/Technical University of Denmark and MCoRDS surveys. However, core-to-core connection is impeded by pervasive aeolian terranes, and Lake Vostok's influence on reflection geometry. Poor radar connection of the two ice cores is attributed to these effects and suboptimal survey design in affected areas. We demonstrate that, while ice sheet internal radar reflections are generally isochronal and can be mapped over large distances, careful survey planning is necessary to extend ice core chronologies to distant regions of the East Antarctic ice sheet.

  18. Methyl iodine over oceans from the Arctic Ocean to the maritime Antarctic

    Science.gov (United States)

    Hu, Qihou; Xie, Zhouqing; Wang, Xinming; Yu, Juan; Zhang, Yanli

    2016-05-01

    Studies about methyl iodide (CH3I), an important atmospheric iodine species over oceans, had been conducted in some maritime regions, but the understanding of the spatial distribution of CH3I on a global scale is still limited. In this study, we reports atmospheric CH3I over oceans during the Chinese Arctic and Antarctic Research Expeditions. CH3I varied considerably with the range of 0.17 to 2.9 pptv with absent of ship emission. The concentration of CH3I generally decreased with increasing latitudes, except for higher levels in the middle latitudes of the Northern Hemisphere than in the low latitudes. For sea areas, the Norwegian Sea had the highest CH3I concentrations with a median of 0.91 pptv, while the Central Arctic Ocean had the lowest concentrations with all values below 0.5 pptv. CH3I concentration over oceans was affected by many parameters, including sea surface temperature, salinity, dissolved organic carbon, biogenic emissions and input from continents, with distinctive dominant factor in different regions, indicating complex biogeochemical processes of CH3I on a global scale.

  19. 36Cl and 53Mn in Antarctic meteorites and 10Be-36Cl dating of Antarctic ice

    International Nuclear Information System (INIS)

    Cosmic-ray-produced 53Mn (tsub(1/2)=3.7x106 years) has been measured in twenty Antarctic meteorites by neutron activation analysis. 36Cl (tsub(1/2)=3.0x105 years) has been measured in fourteen of these objects by tandem accelerator mass spectrometry. Cosmic ray exposure ages and terrestrial ages of the meteorites are calculated from these results and from gases. 14C (tsub(1/2)=5740 years) and 26Al(tsub(1/2)=7.2x105 years) data. The terrestrial ages range from 3x104 to 5x105 years. Many of the L3-Allan Hills chrondrites seem to be a single fall based on these results. In addition, 10Be (tsub(1/2)=1.6x106 years) and 36Cl have been measured in six Antarctic ice samples. The first measurements of 10Be/36Cl ratios in the ice core samples demonstrate a new dating method for ice. (orig.)

  20. Projecting Antarctic ice discharge using response functions from SeaRISE ice-sheet models

    Directory of Open Access Journals (Sweden)

    A. Levermann

    2012-08-01

    Full Text Available The largest uncertainty in projections of future sea-level change still results from the potentially changing dynamical ice discharge from Antarctica. While ice discharge can alter through a number of processes, basal ice-shelf melting induced by a warming ocean has been identified as a major if not the major cause for possible additional ice flow across the grounding line. Here we derive dynamic ice-sheet response functions for basal ice-shelf melting using experiments carried out within the Sea-level Response to Ice Sheet Evolution (SeaRISE intercomparison project with five different Antarctic ice-sheet models. As used here these response functions provide separate contributions for four different Antarctic drainage regions. Under the assumptions of linear-response theory we project future ice-discharge for each model, each region and each of the four Representative Concentration Pathways (RCP using oceanic temperatures from 19 comprehensive climate models of the Coupled Model Intercomparison Project, CMIP-5, and two ocean models from the EU-project Ice2Sea. Uncertainty in the climatic forcing, the oceanic response and the ice-model differences is combined into an uncertainty range of future Antarctic ice-discharge induced from basal ice-shelf melt. The additional ice-loss (Table 6 is clearly scenario-dependent and results in a median of 0.07 m (66%-range: 0.04–0.10 m; 90%-range: −0.01–0.26 m of global sea-level equivalent for the low-emission RCP-2.6 scenario and yields 0.1 m (66%-range: 0.06–0.14 m; 90%-range: −0.01–0.45 m for the strongest RCP-8.5. If only models with an explicit representation of ice-shelves are taken into account the scenario dependence remains and the values change to: 0.05 m (66%-range: 0.03–0.08 m for RCP-2.6 and 0.07 m (66%-range: 0.04–0.11 m for RCP-8.5. These results were obtained using a time delay between the surface warming signal and the subsurface oceanic warming as observed in the CMIP-5 models

  1. Does the Antarctic ozone hole have a future?

    Science.gov (United States)

    Singer, S. Fred

    1988-11-01

    In spite of recent discoveries related to the mechanism of the Antarctic ozone hole (AOH), we do not as yet have a sufficient scientific base to answer important policy questions: is the AOH a completely new phenomenon, or is it are current one? Is it produced by human activities? And what can and should be done about it? I suggest here a hypothesis concerning the cause of the AOH, which may provide at least partial answers.The AOH is more than a scientific curiosity. Its dramatic discovery in 1985 raised fears about the fate of global ozone and provided the impetus for an international effort to limit and roll back the worldwide production of chlorofluorocarbons (CFCs), synthetic chemicals widely used in refrigeration and industrial processes.

  2. Emergence of healing in the Antarctic ozone layer

    Science.gov (United States)

    Solomon, Susan; Ivy, Diane J.; Kinnison, Doug; Mills, Michael J.; Neely, Ryan R.; Schmidt, Anja

    2016-07-01

    Industrial chlorofluorocarbons that cause ozone depletion have been phased out under the Montreal Protocol. A chemically driven increase in polar ozone (or “healing”) is expected in response to this historic agreement. Observations and model calculations together indicate that healing of the Antarctic ozone layer has now begun to occur during the month of September. Fingerprints of September healing since 2000 include (i) increases in ozone column amounts, (ii) changes in the vertical profile of ozone concentration, and (iii) decreases in the areal extent of the ozone hole. Along with chemistry, dynamical and temperature changes have contributed to the healing but could represent feedbacks to chemistry. Volcanic eruptions have episodically interfered with healing, particularly during 2015, when a record October ozone hole occurred after the Calbuco eruption.

  3. Mars weathering analogs - Secondary mineralization in Antarctic basalts

    Science.gov (United States)

    Berkley, J. L.

    1982-01-01

    Alkalic basalt samples from Ross Island, Antarctica, are evaluated as terrestrial analogs to weathered surface materials on Mars. Secondary alteration in the rocks is limited to pneumatolytic oxidation of igneous minerals and glass, rare groundmass clay and zeolite mineralization, and hydrothermal minerals coating fractures and vesicle surfaces. Hydrothermal mineral assemblages consist mainly of K-feldspar, zeolites (phillipsite and chabazite), calcite, and anhydrite. Low alteration rates are attributed to cold and dry environmental factors common to both Antarctica and Mars. It is noted that mechanical weathering (aeolian abrasion) of Martian equivalents to present Antarctic basalts would yield minor hydrothermal minerals and local surface fines composed of primary igneous minerals and glass but would produce few hydrous products, such as palagonite, clay or micas. It is thought that leaching of hydrothermal vein minerals by migrating fluids and redeposition in duricrust deposits may represent an alternate process for incorporating secondary minerals of volcanic origin into Martian surface fines.

  4. Soil water repellency of Antarctic soils (Elephant Point). First results

    Science.gov (United States)

    Pereira, Paulo; Oliva, Marc; Ruiz Fernández, Jesus

    2015-04-01

    Hydrophobicity it is a natural properties of many soils around the world. Despite the large body of research about soil water hydrophobicity (SWR) in many environments, little information it is available about Antarctic soils and their hydro-geomorphological consequences. According to our knowledge, no previous work was carried out on this environment. Soil samples were collected in the top-soil (0-5 cm) and SWR was analysed according to the water drop penetration test. The preliminary results showed that all the soils collected were hydrophilic, however further research should be carried out in order to understand if SWR changes with soil depth and if have implications on soil infiltration during the summer season.

  5. Determination of Antarctic geoid by using global gravity field

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    With Chinese latest global gravity field model WDM94, the authors providethe geoid height and mean free-air gravity anomaly of Antarctica (The range of latitude is from—60° to—90°). In order to conclude and analyze the characters of Antarctic geoid roundly, the authors collect the latest oversea global gravity field model OSU91 (to degree and order 360) and JGMOSU (to degree and order 360), get the corresponding geoid height and mean free-air gravity anomaly. The results arecompared with the results got from WDM94, thus we get the difference. The standard deviation of geoid height between WDM94 and OSU91 is ± 1.90 re;the deviation of geoid between WDM9 and JGMOSU is ± 2.09 m. The standard deviation of mean gravity anomaly are±8.97 mGal and ± 9.32 mGal respectively.

  6. Searching for eukaryotic life preserved in Antarctic permafrost

    Science.gov (United States)

    Onofri, Silvano; Zucconi, Laura; Selbmann, Laura; Ripa, Caterina; Frisvad, Jens Christian; Guglielmin, Mauro; Turchetti, Benedetta; Buzzini, Pietro

    Permafrost is defined as a soil remaining at 0 C or below throughout two or more consecutive years. Mainly present in polar areas, it occurs in all ice-free areas of Continental Antarc-tica. With the evidences of the possible presence of water ice below the surface of Mars and Moon, permafrost is now considered a possible reservoir of prokaryotic and eukaryotic spores outside the Earth. Cultivable fungi and yeasts have been isolated from Antarctic permafrost collected at different depths (233, 316 and 335 cm) in the McMurdo Dry Valleys, the largest ice-free area in Antarctica, and identified with cultural, physiological and molecular methods. Filamentous fungi belonged to the genera Penicillium, Eurotium, Cladosporium, Alternaria, Engyodonthium, Cordiceps, Rhizopus, Aureobasidium, whereas yeasts belonged to the genera Cryptococcus and Sporidiobolus. Penicillia were the most represented, and the most frequently recorded species were Penicillium palitans and P. chrysogenum. Most of the species found have been already recorded in Antarctic ecosystems as well as in other cold habitats (Onofri et al., 2007); for Eurotium amstelodami and Cryptococcus stepposus these are the first isolations in Antarctica. All the filamentous fungal isolates can be defined as mesophilic having optimal growth temperatures at 20-25 C and poor growth at 0 C after prolonged incubation. All the yeast isolates grew within a wide range of temperature (from 4 to 25 C). The molecular anal-yses based on the ITS rDNA sequences, for filamentous fungi, and on D1/D2 domain of LSU rRNA gene and ITS sequences for yeasts, revealed that these genotypes do not deviate from the global gene pool of microorganisms commonly spreading worldwide at present. Annual mean permafrost temperature (MAPT) in the sampling area was -18.8 C in 2008, with daily fluctuations lower than 1 C/day at 1 m of depth, but less 0.5 C/year at the depth of 17 m (Guglielmin pers. com.), and maximum thaw depth not exceeding 1 m

  7. Quasi-biennial modulation of the Antarctic ozone depletion

    Science.gov (United States)

    Lait, Leslie R.; Schoeberl, Mark R.; Newman, Paul A.

    1989-01-01

    The quasi-biennial oscillation (QBO) in total ozone and temperature has been extracted from 9 years of Total Ozone Mapping Spectrometer (TOMS) observations and National Meteorological Center (NMC) analyses. Years in which QBO-related variations in the total ozone and temperature are positive are found to correspond to years with smaller September Antarctic total ozone hole decline rates and vice versa. The QBO appears to be responsible for September decline rate deviations up to 0.4 Dobson units (DU) per day. Also, the QBO at mid-latitudes appears to be better correlated with the 30-mbar tropical QBO winds than with those at 50 mbar. Possible mechanisms that would explain these phenomena are discussed.

  8. Curation and Allocation of the New Antarctic Nakhlite, MIL03346

    Science.gov (United States)

    McBride, K. M.; Righter, K.; Satterwhite, C. E.; Schwarz, C.; Robinson, P.

    2005-01-01

    In January 2004, the ANSMET reconnaissance field team (Fig. 1) working in the Miller Range of the Transantarctic Mountains discovered a 715 g achondrite that was instantly recognized as unique. Named MIL03346, initial processing (NASA Johnson Space Center or JSC) and classification (Smithsonian Institution or SI) revealed this achondrite to be a nakhlite (Fig. 2). MIL03346 is the seventh nakhlite recognized in world collections [2], the third nakhlite returned from Antartica, and the first nakhlite in the US Antarctic collection (Table 1). The following is a summary of the steps taken in the processing and allocating of MIL 03346 and some comparisons to some other lunar and martian meteorites processed and allocated at JSC.

  9. Spatial modelling of wetness for the Antarctic Dry Valleys

    Directory of Open Access Journals (Sweden)

    Glen Stichbury

    2011-03-01

    Full Text Available This paper describes a method used to model relative wetness for part of the Antarctic Dry Valleys using Geographic Information Systems (GIS and remote sensing. The model produces a relative index of liquid water availability using variables that influence the volume and distribution of water. Remote sensing using Moderate Resolution Imaging Spectroradiometer (MODIS images collected over four years is used to calculate an average index of snow cover and this is combined with other water sources such as glaciers and lakes. This water source model is then used to weight a hydrological flow accumulation model that uses slope derived from Light Detection and Ranging (LIDAR elevation data. The resulting wetness index is validated using three-dimensional visualization and a comparison with a high-resolution Advanced Land Observing Satellite image that shows drainage channels. This research demonstrates that it is possible to produce a wetness model of Antarctica using data that are becoming widely available.

  10. Emergence of healing in the Antarctic ozone layer.

    Science.gov (United States)

    Solomon, Susan; Ivy, Diane J; Kinnison, Doug; Mills, Michael J; Neely, Ryan R; Schmidt, Anja

    2016-07-15

    Industrial chlorofluorocarbons that cause ozone depletion have been phased out under the Montreal Protocol. A chemically driven increase in polar ozone (or "healing") is expected in response to this historic agreement. Observations and model calculations together indicate that healing of the Antarctic ozone layer has now begun to occur during the month of September. Fingerprints of September healing since 2000 include (i) increases in ozone column amounts, (ii) changes in the vertical profile of ozone concentration, and (iii) decreases in the areal extent of the ozone hole. Along with chemistry, dynamical and temperature changes have contributed to the healing but could represent feedbacks to chemistry. Volcanic eruptions have episodically interfered with healing, particularly during 2015, when a record October ozone hole occurred after the Calbuco eruption. PMID:27365314

  11. Quality changes of Antarctic krill powder during long term storage

    DEFF Research Database (Denmark)

    Nielsen, Nina Skall; Lu, Henna Fung Sieng; Bruheim, Inge;

    2016-01-01

    Krill is a valuable sustainable resource of omega-3 fatty acids and protein, which may be processed into a krill powder for human consumption. The objective of this study was to investigate the stability of krill powder when stored for up to 12 months at room temperature. In addition, the effect...... and a concomitant decrease in antioxidants, tocopherol, and astaxanthin was observed. In addition, there was a minor decrease in phospholipids and n-3 fatty acids; however, storage at vacuum improved the oxidative stability of krill powder. Practical applications: For the use of krill powder in human nutrition......, it is important, that the quality and stability is sufficiently high to retain the nutritional value during storage. This study contributes with information about the stability during storage up to 12 months at room temperature and the effect of packaging the powder in vacuum. Antarctic krill (Euphausia superba...

  12. Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula - 1985, SDLS CD-ROM vol 16

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1985 field season along the north side of the Antarctic-Peninsula by the British...

  13. Change Analysis of Antarctic Ice Shelves Based on Multiple Remote Sensing Products

    Science.gov (United States)

    Tian, Yixiang; Weng, Hexia; Lv, Da; Tong, Xiaohua; Li, Rongxing

    2016-06-01

    The Antarctic ice sheet is well known as the most sensitive and key issue in the global climate change research and is playing a more and more important role for the global sea level change. Measurement of changes in area and mass of the Antarctic ice sheet is critically important and has been made by using different remote sensing technologies and ground exploration data. Sequential mapping of Antarctic boundaries provides a simple and direct method for measuring the area and volume if ice sheet or ice shelves advances or retreats in the Antarctic coasts. Our results show that the total ice shelf area is retreated between 1963 and 2009. However, the trend for each ice shelf is quite different.

  14. Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula 1987-88, SDLS CD-ROM vol 24

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1987-88 in the Antarctic Peninsula, Antarctica, by the Japan National Oil...

  15. Antarctic Flight Line Maps = Map-Line Indexes of Antarctica Aerial Photos: Pre 1950

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Antarctic Fight Line Maps collection is comprised of 1:250,000 scale topographic maps over Antarctica with original hand-drawn flight lines for aerial...

  16. Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula - 1988-1989, SDLS CD-ROM vol 25

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1988-89 in the Antarctic Peninsula, Antarctica, by the Japan National Oil...

  17. 78 FR 27260 - Comment Request: Antarctic Conservation Act Application Permit Form

    Science.gov (United States)

    2013-05-09

    ... type of object to be taken (plant, native mammal, or native bird. Use of the Information The purpose of... Act of 1978, Public Law 95-541, as amended by the Antarctic Science, Tourism, and Conservation Act...

  18. Age, growth and distribution of the Antarctic fish Chaenocephalus aceratus based on otoliths

    Directory of Open Access Journals (Sweden)

    Ryszard Jacek Traczyk

    2015-10-01

    Żabrowski, M. 2000. The osteology and ossification variability of the skull of antarctic white-blooded fish Chaenodraco wilsoni Regan, 1914 (Channichthyidae, Notothenioidei. W-wa : Acta Icht. Piscat. 30 (2: 111-126.

  19. 78 FR 56744 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2013-09-13

    ... Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and Conservation Act of... drilling would not go as deep as the base of the glacier or the source of the brine. Location: ASPA...

  20. Controlled, distributed data management of an Antarctic time series

    Science.gov (United States)

    Leadbetter, Adam; Connor, David; Cunningham, Nathan; Reynolds, Sarah

    2010-05-01

    The Rothera Time Series (RaTS) presents over ten years of oceanographic data collected off the Antarctic Peninsula comprising conductivity, temperature, depth cast data; current meter data; and bottle sample data. The data set has been extensively analysed and is well represented in the scientific literature. However, it has never been available to browse as a coherent entity. Work has been undertaken by both the data collecting organisation (the British Antarctic Survey, BAS) and the associated national data centre (the British Oceanographic Data Centre, BODC) to describe the parameters comprising the dataset in a consistent manner. To this end, each data point in the RaTS dataset has now been ascribed a parameter usage term, selected from the appropriate controlled vocabulary of the Natural Environment Research Council's Data Grid (NDG). By marking up the dataset in this way the semantic richness of the NDG vocabularies is fully accessible, and the dataset can be then explored using the Global Change Master Directory keyword set, the International Standards Organisation topic categories, SeaDataNet disciplines and agreed parameter groups, and the NDG parameter discovery vocabulary. We present a single data discovery and exploration tool, a web portal which allows the user to drill down through the dataset using their chosen keyword set. The spatial coverage of the chosen data is displayed through a Google Earth web plugin. Finally, as the time series data are held at BODC and the discrete sample data held at BAS (which are separate physical locations), a mechanism has been established to provide metadata from one site to another. This takes the form of an Open Geospatial Consortium Web Map Service server at BODC feeding information into the portal hosted at BAS.

  1. Reducing uncertainties in projections of Antarctic ice mass loss

    Science.gov (United States)

    Durand, G.; Pattyn, F.

    2015-11-01

    Climate model projections are often aggregated into multi-model averages of all models participating in an intercomparison project, such as the Coupled Model Intercomparison Project (CMIP). The "multi-model" approach provides a sensitivity test to the models' structural choices and implicitly assumes that multiple models provide additional and more reliable information than a single model, with higher confidence being placed on results that are common to an ensemble. A first initiative of the ice sheet modeling community, SeaRISE, provided such multi-model average projections of polar ice sheets' contribution to sea-level rise. The SeaRISE Antarctic numerical experiments aggregated results from all models devoid of a priori selection, based on the capacity of such models to represent key ice-dynamical processes. Here, using the experimental setup proposed in SeaRISE, we demonstrate that correctly representing grounding line dynamics is essential to infer future Antarctic mass change. We further illustrate the significant impact on the ensemble mean and deviation of adding one model with a known bias in its ability of modeling grounding line dynamics. We show that this biased model can hardly be identified from the ensemble only based on its estimation of volume change, as ad hoc and untrustworthy parametrizations can force any modeled grounding line to retreat. However, tools are available to test parts of the response of marine ice sheet models to perturbations of climatic and/or oceanic origin (MISMIP, MISMIP3d). Based on recent projections of Pine Island Glacier mass loss, we further show that excluding ice sheet models that do not pass the MISMIP benchmarks decreases the mean contribution and standard deviation of the multi-model ensemble projection by an order of magnitude for that particular drainage basin.

  2. Quality Assurance of A Solar Uv Network In The Antarctic

    Science.gov (United States)

    Lakkala, K.; Redondas, A.; Koskela, T.; Taalas, P.; Torres, C.; Cuevas, E.; Deferrari, G.

    This work will present the quality assurance of the solar UV network of the Mea- surement of Antarctic Radiance for monitoring the ozone layer (MAR) -project. The network consists on three NILU-UV multichannel filter radiometers, which have been installed at the Argentinean Antarctic bases of Vicecomodoro Marambio and Bel- grano II and at the Centro Austral De Investigationes Cientificas (CADIC) in Ushuaia in December 1999­January 2000. The location of the three sites gives a possibility to study the impact of the daily changes of the polar vortex on ozone and UV radiation reaching the ground: Belgrano being located mostly inside the vortex, Marambio at the edge and Ushuaia mostly outside the vortex. The network has been established as co-operation between the Instituto Nacional de Meteorologia (INM), Spain, the Insti- tuto Antártico Argentino (IAA) from Dirrección Nacional del Antártico (DNA), the Finnish Meteorological Institute (FMI) and the CADIC. The quality assurance procedure, which includes a travelling reference and relative lamp tests, will be described. The travelling reference has been provided to trans- fer calibration factors from the absolute reference spectroradiometer to the NILU-UV radiometers of the network. Results of solar comparisons between the travelling ref- erence and the site instruments of Marambio and Ushuaia will be presented. Relative lamp tests are performed every second week in order to monitor the stability of the instruments. Time series of these lamp tests are analysed to perform corrections to each channel during the measurement period.

  3. Assessing environmental conditions of Antarctic footpaths to support management decisions.

    Science.gov (United States)

    Tejedo, Pablo; Benayas, Javier; Cajiao, Daniela; Albertos, Belén; Lara, Francisco; Pertierra, Luis R; Andrés-Abellán, Manuela; Wic, Consuelo; Luciáñez, Maria José; Enríquez, Natalia; Justel, Ana; Reck, Günther K

    2016-07-15

    Thousands of tourists visit certain Antarctic sites each year, generating a wide variety of environmental impacts. Scientific knowledge of human activities and their impacts can help in the effective design of management measures and impact mitigation. We present a case study from Barrientos Island in which a management measure was originally put in place with the goal of minimizing environmental impacts but resulted in new undesired impacts. Two alternative footpaths used by tourist groups were compared. Both affected extensive moss carpets that cover the middle part of the island and that are very vulnerable to trampling. The first path has been used by tourists and scientists since over a decade and is a marked route that is clearly visible. The second one was created more recently. Several physical and biological indicators were measured in order to assess the environmental conditions for both paths. Some physical variables related to human impact were lower for the first path (e.g. soil penetration resistance and secondary treads), while other biochemical and microbiological variables were higher for the second path (e.g. β-glucosidase and phosphatase activities, soil respiration). Moss communities located along the new path were also more diverse and sensitive to trampling. Soil biota (Collembola) was also more abundant and richer. These data indicate that the decision to adopt the second path did not lead to the reduction of environmental impacts as this path runs over a more vulnerable area with more outstanding biological features (e.g. microbiota activity, flora and soil fauna diversity). In addition, the adoption of a new route effectively doubles the human footprint on the island. We propose using only the original path that is less vulnerable to the impacts of trampling. Finally from this process, we identify several key issues that may be taken into account when carrying out impact assessment and environmental management decision-making in the

  4. Microbial mineralization processes in Antarctic soils and on plant material

    International Nuclear Information System (INIS)

    Soil samples and different plant material from the maritime and continental Antarctic were analyzed for their actual and potential respiration by different methods: total CO2-evolution, biological oxygen demand and use of 14C-labeled glucose which may serve as a model for dissolved organic carbohydrates. Since these methods are argued to indicate the mineralization of different fractions of the total organic material by different actual populations, a comparison between the data from these techniques is carried out with regard to their contributions of the total organic matter debris in these environments. The part of respired material calculated from 14C-studies may contribute to nearly 90% of the metabolized material. Results show that the individual fractions differ significantly with respect to the parent material. There are several aspects which have to be taken into account when looking at these data: the original content of water; the contents of dissolved and particulate carbohydrates; and, other edaphic factors. Of special interest is the overall respiration of plant material (mainly lichens) which is strongly influenced by the bacterial respiration of dissolved carbohydrates, probably by ongrowing organisms due to their efficiency in using dissolved organic matter. In terms of respiratory activity, the (bacterial) respiration of glucose may contribute to more than 50% of the total CO2-evolution. This influences considerably the modeling of overall respiration of plant material in those environments where close interactions between different parts of the system are very important for their life strategy. Further, the bacterial part may be an overlooked part of metabolic rates in Antarctic lichens

  5. Antarctic subglacial lake exploration: first results and future plans

    Science.gov (United States)

    Siegert, Martin J.; Priscu, John C.; Wadham, Jemma L.; Lyons, W. Berry

    2016-01-01

    After more than a decade of planning, three attempts were made in 2012–2013 to access, measure in situ properties and directly sample subglacial Antarctic lake environments. First, Russian scientists drilled into the top of Lake Vostok, allowing lake water to infiltrate, and freeze within, the lower part of the ice-core borehole, from which further coring would recover a frozen sample of surface lake water. Second, UK engineers tried unsuccessfully to deploy a clean-access hot-water drill, to sample the water column and sediments of subglacial Lake Ellsworth. Third, a US mission successfully drilled cleanly into subglacial Lake Whillans, a shallow hydraulically active lake at the coastal margin of West Antarctica, obtaining samples that would later be used to prove the existence of microbial life and active biogeochemical cycling beneath the ice sheet. This article summarizes the results of these programmes in terms of the scientific results obtained, the operational knowledge gained and the engineering challenges revealed, to collate what is known about Antarctic subglacial environments and how to explore them in future. While results from Lake Whillans testify to subglacial lakes as being viable biological habitats, the engineering challenges to explore deeper more isolated lakes where unique microorganisms and climate records may be found, as exemplified in the Lake Ellsworth and Vostok missions, are considerable. Through international cooperation, and by using equipment and knowledge of the existing subglacial lake exploration programmes, it is possible that such environments could be explored thoroughly, and at numerous sites, in the near future. PMID:26667917

  6. Development of a multi-parameter system for Antarctic researching

    Science.gov (United States)

    Garcia, Alicia; Peci, Luis Miguel; Berrocoso, Manuel; Fernandez-Ros, Alberto; Marrero, Jose Manuel; Ortiz, Ramon

    2014-05-01

    This work describes the development of a multi-parameter system for antarctic researching. The system permits the remote access and the connection of several modules in a network. An embedded ARM processor has been used, allowing a great flexibility in hardware configuration.The advantage of the system presented in this work is that it allows the rapid development of a monitoring network that uses the latest technologies of embedded systems. These embedded systems offer the possibility of developing the software necessary for managing the sensors and instruments available. Data can be transmitted in near real time or on demand to a Data Reception Center (DRC). The local storage allows retrieving data when the transmission fails and uses only short transmission periods rather than continuous transmission. The price of both hardware and software is very low. The use of a complete Linux solution (Debian) as Operating System permits a quick, easy application development to control sensors and communications. This provides all the capabilities required and great stability with relatively low energy consumption. The cost of the components and applications development is low since they are widely used in different fields. Sensors and commercial modules have been combined with other self-developed modules. The Modular System described has been deployed at Deception Island (Antarctica), within the Spanish Antarctic Program, and has proved successful for monitoring and researching the geodinamical activity, with proven reliability and efficient operation under extreme conditions. Deception Islan is an active volcano with some geothermal areas, this fact has allowed to develop a power system using Peltier cells. In another context, i.e., the recent volcanic activity on El Hierro Island (Canary Islands) in 2011, this technology has been used for the seismic equipment and GPS systems deployed, thus showing its efficiency in the monitoring of a volcanic crisis.

  7. A Nutritional-Toxicological Assessment of Antarctic Krill Oil versus Fish Oil Dietary Supplements

    OpenAIRE

    Bengtson Nash, Susan M.; Martin Schlabach; Nichols, Peter D.

    2014-01-01

    Fish oil dietary supplements and complementary medicines are pitched to play a role of increasing strategic importance in meeting daily requirements of essential nutrients, such as long-chain (≥C20, LC) omega-3 polyunsaturated fatty acids and vitamin D. Recently a new product category, derived from Antarctic krill, has been launched on the omega-3 nutriceutical market. Antarctic krill oil is marketed as demonstrating a greater ease of absorption due to higher phospholipid content, as being so...

  8. Structure and Steroidogenesis of the Placenta in the Antarctic Minke Whale (Balaenoptera bonaerensis)

    OpenAIRE

    SASAKI, Motoki; AMANO, Yoko; HAYAKAWA, Daisuke; Tsubota, Toshio; Ishikawa, Hajime; MOGOE, Toshihiro; OHSUMI, Seiji; TETSUKA, Masafumi; MIYAMOTO, Akio; Fukui, Yutaka; BUDIPITOJO, Teguh; KITAMURA, Nobuo

    2012-01-01

    Abstract There are few reports describing the structure and function of the whale placenta with the advance of pregnancy. In this study, therefore, the placenta and nonpregnant uterus of the Antarctic minke whale were observed morphologically and immunohistochemically. Placentas and nonpregnant uteri were collected from the 15th, 16th and 18th Japanese Whale Research Programme with Special Permit in the Antarctic (JARPA) and 1st JARPA II organized by the Institute of Cetacean Research in Toky...

  9. Review of Antarctic climate change and the environment edited by John Turner et al.

    OpenAIRE

    Orheim, Olav

    2011-01-01

    This impressive report from the Scientific Committee on Antarctic Research (SCAR) covers nearly 400 pages of text with more than 100 additional pages of references. Under the clearly very able leadership of John Turner of the British Antarctic Survey, the nine editors have coordinated more than 100 contributors to produce a comprehensive review of our knowledge of Antarctica’s climate up to 2007. (Published: 21 February 2011) Citation: Polar Research 2011, 30, 5985, DOI: 10.3402/polar.v...

  10. Paleomagnetism and tectonics of the South Shetland Islands and the northern Antarctic Peninsula

    OpenAIRE

    Poblete, F.; Arriagada, C.; Roperch, Pierrich; Astudillo, N.; Herve, F; Kraus, S.; J. P. Le Roux

    2011-01-01

    New paleomagnetic data presented here from 61 sites in Paleozoic, Mesozoic and Cenozoic igneous and sedimentary rocks from the Antarctic Peninsula and the South Shetland Islands constrain the relative motion of the Antarctic Peninsula since the mid-Cretaceous and allow the quantification of tectonic rotation between the different blocks recognized within the area. Paleozoic and Jurassic results failed the fold test and suggest an important remagnetization in the area. The similarity between t...

  11. EOS Microwave Limb Sounder observations of the Antarctic polar vortex breakup in 2004

    OpenAIRE

    Manney, G. L.; M. L. Santee; N. J. Livesey; Froidevaux, L.; W. G. Read; Pumphrey, H. C.; Waters, J.W.; Pawson, S.

    2005-01-01

    New observations from the Microwave Limb Sounder (MLS) on NASA's Aura satellite give a detailed picture of the spring Antarctic polar vortex breakup throughout the stratosphere, with the first daily global HCl profiles providing an unprecedentedly clear view of transport in the lower stratosphere. Poleward transport at progressively lower levels, filamentation, and mixing are detailed in MLS HCl, N2O, H2O, and O3 as the 2004 Antarctic vortex broke up from the top down in early October through...

  12. Resistance of Antarctic black fungi and cryptoendolithic communities to simulated space and Martian conditions

    OpenAIRE

    Onofri, S.; Barreca, D.; Selbmann, L.; D. Isola; E. Rabbow; Horneck, G.; de Vera, J.P.P.; Hatton, J.; Zucconi, L.

    2008-01-01

    Dried colonies of the Antarctic rock-inhabiting meristematic fungi Cryomyces antarcticus CCFEE 515, CCFEE 534 and C. minteri CCFEE 5187, as well as fragments of rocks colonized by the Antarctic cryptoendolithic community, were exposed to a set of ground-based experiment verification tests (EVTs) at the German Aerospace Center (DLR, Köln, Germany). These were carried out to test the tolerance of these organisms in view of their possible exposure to space conditions outside of the International...

  13. Environmental effects of the US Antarctic Program`s use of balloons in Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    McCold, L.N.; Eddlemon, G.K.; Blasing, T.J.

    1995-06-01

    The USAP uses balloons in Antarctica to conduct scientific research, to facilitate safe air transport, and to provide data for global weather predictions. However, there is the possibility that balloons or their payloads may adversely affect Antarctic fauna or flora. The purpose of this study is to provide background information upon which the USAP may draw when complying with its responsibilities under the National Environmental Policy Act of 1969, the Antarctic Treaty, and the Madrid Protocol.

  14. The bivalve Laternula elliptica: physiological and molecular response to changing coastal Antarctic environments

    OpenAIRE

    Husmann, Gunnar

    2013-01-01

    Increasing temperatures and glacier-disintegration at the Western Antarctic Peninsula (WAP) are presently altering environmental conditions in shallow coastal areas. Rising water temperatures, enhanced ice scouring impacts as well as increasing input of inorganic sediments from melt water runoff are anticipated to particularly affect slow growing sessile benthic filter feeders like the Antarctic soft shell clam Laternula elliptica, a long-lived species which is a major component of the nearsh...

  15. Conceptual View Representation of the Brazilian Information System on Antarctic Environmental Research

    OpenAIRE

    Zorrilla, R.; Poltosi, M; Gadelha, L; Porto, F.; Moura, A.; Dalto, A; Lavrado, H.P.; Valentin, Y; Tenório, M; E Xavier

    2014-01-01

    Data generated by environmental research in Antarctica are essential in evaluating how its biodiversity and environment are affected by global-scale changes triggered by ever-increasing human activities. In this work, we describe BrAntIS, the Brazilian Information System on Antarctic Environmental Research, which enables the acquiring, storing, and querying of research data generated by the Brazilian National Institute for Science and Technology on Antarctic Environmental Research. BrAntIS' d...

  16. Variability in the Antarctic Marginal Ice Zone and Pack Ice in Observations and NCAR CESM

    Science.gov (United States)

    Stroeve, J. C.; Campbell, G. G.; Holland, M. M.; Landrum, L.

    2015-12-01

    Sea ice around Antarctica reached another record high extent in September 2014, recording a maximum extent of more than 20 million km2 for the first time since the modern satellite data record began in October 1978. This follows previous record maxima in 2012 and 2013, resulting in an overall increase in Antarctic September sea ice extent of 1.3% per decade since 1979. Several explanations have been put forward to explain the increasing trends, such as anomalous short-term wind patterns that both grow and spread out the ice, and freshening of the surface ocean layer from increased melting of floating ice from the continent. These positive trends in Antarctic sea ice are at odds with climate model forecasts that suggest the sea ice should be declining in response to increasing greenhouse gases and stratospheric ozone depletion. While the reasons for the increases in total extent remain poorly understood, it is likely that these changes are not just impacting the total ice extent, but also the distribution of pack ice, the marginal ice zone (MIZ) and polynyas, with important ramifications for phytoplankton productivity that in turn impact zooplankton, fish, sea birds and marine mammals. This study evaluates changes in the distribution of the pack ice, polynyas and the marginal ice zone around Antarctica from two sea ice algorithms, the NASA Team and the Bootstrap. These results are further compared with climate model simulations from the CESM large ensemble output. Seasonal analysis of the different ice types using NASA Team and Bootstrap shows that during ice advance, the ice advances as pack ice, with a seasonal peak in September (broader peak for Bootstrap), and as the pack ice begins to retreat, it first converts to a wide area of MIZ, that reaches its peak around November (NASA Team) or December (Bootstrap). CESM also shows a similar seasonal cycle, with a peak in the pack ice in August, and a December/January peak in the MIZ. Seasonal variability and trends are

  17. Antarctic climate variability from ice core records over the last two millennia

    Science.gov (United States)

    Braida, Martina; Stenni, Barbara; Masson-Delmotte, Valerie; Dreossi, Giuliano; Oerter, Hans; Selmo, Enricomaria; Severi, Mirko; Goosse, Hugues; Mezgec, Karin

    2013-04-01

    The climate of the past can be successfully investigated through the study of polar ice sheets. Paleotemperature reconstructions from Antarctic ice cores are based on water isotope profiles, thanks to the existing relationship between δ18O (or δD) and the temperature at the site. Here we present the climate record of the past 2000 years resulting from the stable isotope analysis of the ice core drilled at Talos Dome in East Antarctica from 2003 to 2007 in the framework of the European TALDICE (TALos Dome Ice CorE) project. Talos Dome (72°49'S, 159°11'E; 2315 m; -41°C) is an ice dome on the edge of the East Antarctic plateau. The snow accumulation rate of the site (80 kg m-2 yr-1) allows extracting high-resolution data for the past millennia. The main moisture sources of snow precipitation at this near-coastal site are located in the Indian Ocean and the Ross Sea. Isotopic analyses of TALDICE detailed (10 cm) samples have been performed in the framework of the ESF-HOLOCLIP project, whose main objective is to integrate the ice core, the marine core and the modeling data to investigate the climate variability of the high latitude southern hemisphere over the Holocene. The isotopic record obtained from the TALDICE ice core is here compared with a shallow firn core (89 m long) previously drilled at Talos Dome, at a 5 km distance, and covering the past 800 years. The two isotopic records are stacked to reduce the stratigraphic noise and compared with other available isotopic records from Antarctica to highlight common trends and regional variability in the climatic signal over the past two millennia. We compare the data with a simulation performed with a three-dimensional earth system model of intermediate complexity (LOVECLIM) with and without data assimilation. Considering the δ18O profile from the TALDICE ice core and comparing it with the ones from the other available records we can observe common negative isotopic anomalies in the period from about 1450 to

  18. Peatlands, methane cycling and hyperthermals on the East Antarctic continent in the early Eocene.

    Science.gov (United States)

    Bendle, J. A.; Toney, J. L.; Seki, O.; Krishnan, S.; Pagani, M.; Inglis, G.; Pancost, R. D.; Bijl, P.; Bohaty, S. M.; Schouten, S.; Pross, J.; Contreras, L.; Brinkhuis, H.; Roehl, U.; Jamieson, S.

    2012-12-01

    The high temperature, high pCO2 world of the early Eocene (ca.55 to 49 Ma) greenhouse may be an analogue for the future response of the biosphere and global carbon cycle, if anthropogenic, atmospheric CO2 forcing continues unabated. Here we present an early Eocene record inferring that orbital-scale changes in peatland extent and methanogenesis in coastal wetlands on Antarctica played an important role in the carbon cycle of this greenhouse world. Terrestrial biomarkers were analyzed from IODP Expedition 318 - Site U1356A, situated along the Wilkes Land margin of East Antarctica. The bacterial-derived, C31 (17αβ,21ββ) homohopane within a relatively immature hopane assemblage from Site U1356A, suggests that wetland environments were present on the Antarctica continent in the early Eocene. The timing of the fluctuations in the concentrations and the molecular structure - the ββ/(αβ+ββ) ratio - indicate that the extent of these wetlands fluctuated in response to external, orbital forcing. The compound-specific carbon isotope values (δ13C) of hopanes are consistently 5 to 10 permil lower than those of the higher plant n-alkanes, which suggests that the bacterial precursor organisms were likely a mixture of heterotrophs and methanotrophs. The longer term trends and apparently orbitally-paced hyperthermals observed in the biomarker measurements (including compound specific δ13C and δD) are consistent with changes in the TEXH86 sea-surface temperature proxy and suggest an important link between regional temperatures, the hydrological cycle and methanogenesis in wetlands on the early Eocene, Antarctic continent. For confirmation we are comparing the biomarker data with model outputs and additional palynological analyses. As well as exploring new biomarker data from other early Eocene sites to determine if the orbitally-driven expansion of peatlands along the Wilkes Land margin, East Antarctica applies to wider Eocene coastal environments, or if the peatland

  19. Variability of the Antarctic Circumpolar Current transport through the Fawn Trough, Kerguelen Plateau

    Science.gov (United States)

    Vivier, Frédéric; Park, Young-Hyang; Sekma, Hela; Le Sommer, Julien

    2015-04-01

    The Kerguelen Plateau is a major topographic obstacle to the eastward flowing Antarctic Circumpolar Current (ACC). While approximately two-third of the ACC transport is diverted to the North, most of the remaining flow engulfs in the Fawn Trough, the only deep passage across the plateau. As part of the TRACK (TRansport ACross the Kerguelen plateau) project, three mooring lines of current meters were deployed in the Fawn Trough for one year in February 2009, underneath ground-track 94 of the Jason-2 satellite altimeter. Full depth CTD-LADCP casts carried out during the deployment cruise were previously analyzed to provide a comprehensive description of the regional circulation, featuring in particular a volume transport of ~43 Sv across the Fawn Trough (Park et al., 2009). Here we present a time series of the transport in the Fawn Trough estimated from current meter observations, featuring a mean eastward transport of 34 Sv (possibly biased low by at most 5 Sv) and a root mean squared variability of 6 Sv, consistent with LADCP estimates (43 Sv in February 2009 and 38 Sv in January 2010). In addition, we analyze to what extent the transport can be directly monitored from along-track satellite altimeter data, which would enable study of the variability of the Fawn Trough Current from a now 20-year long archive. The ability to reconstruct the flow from a limited set of moored instruments as well as from altimeter-derived surface geostrophic velocity is further assessed from synthetic data extracted from a high-resolution peri-Antarctic simulation. While a canonical method to derive transport from altimetry, previously applied to the Malvinas Current, gives here unsatisfactory comparisons with in situ estimates, an ad hoc approach using only the two northernmost mooring lines yields an estimate well correlated (~0.8) with in situ transport at subseasonal time scales during the one year period of observations. At interannual time scales, however, both methods provide

  20. Combined analysis of the chloroplast genome and transcriptome of the Antarctic vascular plant Deschampsia antarctica Desv.

    Directory of Open Access Journals (Sweden)

    Jungeun Lee

    Full Text Available BACKGROUND: Antarctic hairgrass (Deschampsia antarctica Desv. is the only natural grass species in the maritime Antarctic. It has been researched as an important ecological marker and as an extremophile plant for studies on stress tolerance. Despite its importance, little genomic information is available for D. antarctica. Here, we report the complete chloroplast genome, transcriptome profiles of the coding/noncoding genes, and the posttranscriptional processing by RNA editing in the chloroplast system. RESULTS: The complete chloroplast genome of D. antarctica is 135,362 bp in length with a typical quadripartite structure, including the large (LSC: 79,881 bp and small (SSC: 12,519 bp single-copy regions, separated by a pair of identical inverted repeats (IR: 21,481 bp. It contains 114 unique genes, including 81 unique protein-coding genes, 29 tRNA genes, and 4 rRNA genes. Sequence divergence analysis with other plastomes from the BEP clade of the grass family suggests a sister relationship between D. antarctica, Festuca arundinacea and Lolium perenne of the Poeae tribe, based on the whole plastome. In addition, we conducted high-resolution mapping of the chloroplast-derived transcripts. Thus, we created an expression profile for 81 protein-coding genes and identified ndhC, psbJ, rps19, psaJ, and psbA as the most highly expressed chloroplast genes. Small RNA-seq analysis identified 27 small noncoding RNAs of chloroplast origin that were preferentially located near the 5'- or 3'-ends of genes. We also found >30 RNA-editing sites in the D. antarctica chloroplast genome, with a dominance of C-to-U conversions. CONCLUSIONS: We assembled and characterized the complete chloroplast genome sequence of D. antarctica and investigated the features of the plastid transcriptome. These data may contribute to a better understanding of the evolution of D. antarctica within the Poaceae family for use in molecular phylogenetic studies and may also help researchers

  1. MT soundings in south Shetland Islands and Antarctic Peninsula (Antarctica). Constraints to the crustal structure of the Bransfield strait conjugated continental margins

    International Nuclear Information System (INIS)

    Complete text of publication follows. The South Shetland Block was separated from the Antarctic Peninsula during the opening of the Bransfield Strait since the Pliocene (about 3.3 Ma). The Bransfield basin is developed by the interaction of two tectonic processes that continue active up to Present: the back-arc extension related to the subduction of the former Phoenix plate oceanic crust along the South Shetland trench and the transtensional deformation associated to the western end of the sinistral Scotia-Antarctic plate boundary along the South Scotia Ridge fault zone. In this tectonic framework 12 MT broadband data (BBMT) were recorded along a NW-SE transect orthogonal to the Bransfield Strait, with Metronix ADU-06 equipments, during 2008 and 2009 International Polar Year field surveys. Due to the difficult access of the region and in order to compare the resistivity crustal features, MT soundings were grouped in three sectors representing the different tectonic settings. In the South Shetland Block 4 MT soundings were located in Livingston Island (3 in Byers Peninsula and one in Hurd Peninsula) and suggest the presence of conductive Cretaceous to Cenozoic sedimentary and volcanic rocks above the resistive and heterogeneous metamorphic basement that outcrop in Hurd Peninsula. Southwards, 7 MT sounding were situated around the Quaternary volcanic caldera of Deception Island, formed on the fault system separating the South Shetland Block and the Bransfield basin. Conductive bodies highlight the location of the main magma chambers. Finally, in the Antarctic Peninsula northern margin a MT sounding was obtained in Isla Larga, near the O'Higgins base that constitutes one of the scarce islands of this region not covered by ice during the summer. This MT sounding suggest a 3D complex resistivity structure related to the metamorphic rocks intruded by basic dykes. These MT soundings may contribute to improve the scarce available data on the crustal structure of this

  2. The response of the East Antarctic ice-sheet to the evolving tectonic configuration of the Transantarctic Mountains

    Science.gov (United States)

    Kerr, Andrew; Huybrechts, Philippe

    1999-12-01

    The landscape of the Transantarctic Mountains is the result of the coupled evolution of the West Antarctic rift system and the East Antarctic ice-sheet. Studies of this glacial-tectonic system generally assume that the evolving surface elevation of the Transantarctic Mountains is a key determinant of the changing East Antarctic ice-sheet dynamics between the Miocene and today. Here, we extend previous work [Huybrechts, Ph., 1993. Glaciological modelling of the Late Cenozoic East Antarctic ice-sheet: stability or dynamism? Geografiska Annaler Stockholm, 75A (4) 221-238.] by using numerical models of the ice-sheet and lithosphere to examine the impact of different bedrock surface elevations of the Transantarctic Mountains on ice-sheet dynamics. There are widely different interpretations of the evolution of the Transantarctic Mountains from the available data, so we explore bedrock surface elevations suggested by empirical evidence in recent papers about the sensitivity of the Late Cenozoic ice-sheet. The results show that the surface elevation of individual mountain blocks has only a very local effect on ice-sheet dynamics. The existing mountain blocks of the Transantarctic Mountains, which force inland ice to drain through troughs adjacent to the mountain blocks, were overriden by inland ice when bedrock elevations were 1 km lower. When the troughs through the mountains were less well developed, in the Pliocene or Miocene, inland ice was thicker and ice-surface gradients and ice-velocities across the mountains were higher. This led to more active and erosive outlet glaciers through the mountains and the further development of these troughs. From these results, the key determinant of East Antarctic ice dynamics appears to be the interplay between the development of major troughs through the Transantarctic Mountains and rising mountain elevations. The glacial history of the central Transantarctic Mountain ranges was very different to that of more peripheral mountain

  3. Negative magnetic anomaly over Mt. Resnik, a subaerially erupted volcanic peak beneath the West Antarctic Ice Sheet

    Science.gov (United States)

    Behrendt, John C.; Finn, C.; Morse, D.L.; Blankenship, D.D.

    2006-01-01

    negative anomalies indicate volcanic activity during a period of magnetic reversal and therefore must also be at least 780 ka. The spatial extent and volume of volcanism can now be reassessed for the 1.2 ?? 106 km2 region of the WAIS characterized by magnetic anomalies defining interpreted volcanic centers associated with the West Antarctic rift system. The CWA covers an area of 3.54 ?? 105 km2; forty-four percent of that area exhibits short-wavelength, high-amplitude anomalies indicative of volcanic centers and subvolcanic intrusions. This equates to an area of 0.51 ?? 105 km2 and a volume of 106 km3 beneath the ice-covered West Antarctic rift system, of sufficient extent to be classified as a large igneous province interpreted to be of Oligocene to recent age.

  4. Outline of a small unmanned aerial vehicle (Ant-Plane) designed for Antarctic research

    Science.gov (United States)

    Funaki, Minoru; Hirasawa, Naohiko; the Ant-Plane Group

    As part of the Ant-Plane project for summertime scientific research and logistics in the coastal region of Antarctica, we developed six types of small autonomous UAVs (unmanned aerial vehicles, similar to drones; we term these vehicles ‘Ant-Planes’) based on four types of airframe. In test flights, Ant-Plane 2 cruised within 20 m accuracy along a straight course during calm weather at Sakurajima Volcano, Kyushu, Japan. During a period of strong winds (22 m/s) at Mt. Chokai, Akita Prefecture, Japan, Ant-Plane 2 maintained its course during a straight flight but deviated when turning leeward. An onboard 3-axis magneto-resistant magnetometer (400 g) recorded variations in the magnetic field to an accuracy of 10 nT during periods of calm wind, but strong magnetic noise was observed during high winds, especially head winds. Ant-Plane 4-1 achieved a continuous flight of 500 km, with a maximum flight altitude of 5690 m. The Ant-Plane can be used for various types of Antarctic research as a basic platform for airborne surveys, but further development of the techniques employed in takeoff and landing are required, as well as ready adjustment of the engine and the development of small onboard instruments with greater reliability.

  5. Southern Ocean phytoplankton turnover in response to stepwise Antarctic cooling over the past 15 million years

    Science.gov (United States)

    Crampton, James S.; Cody, Rosie D.; Levy, Richard; Harwood, David; McKay, Robert; Naish, Tim R.

    2016-06-01

    It is not clear how Southern Ocean phytoplankton communities, which form the base of the marine food web and are a crucial element of the carbon cycle, respond to major environmental disturbance. Here, we use a new model ensemble reconstruction of diatom speciation and extinction rates to examine phytoplankton response to climate change in the southern high latitudes over the past 15 My. We identify five major episodes of species turnover (origination rate plus extinction rate) that were coincident with times of cooling in southern high-latitude climate, Antarctic ice sheet growth across the continental shelves, and associated seasonal sea-ice expansion across the Southern Ocean. We infer that past plankton turnover occurred when a warmer-than-present climate was terminated by a major period of glaciation that resulted in loss of open-ocean habitat south of the polar front, driving non-ice adapted diatoms to regional or global extinction. These findings suggest, therefore, that Southern Ocean phytoplankton communities tolerate “baseline” variability on glacial–interglacial timescales but are sensitive to large-scale changes in mean climate state driven by a combination of long-period variations in orbital forcing and atmospheric carbon dioxide perturbations.

  6. Antarctic network of lamp-calibrated multichannel radiometers for continuous ozone and uv radiation data

    Science.gov (United States)

    Redondas, A.; Torres, C.; Meinander, O.; Lakkala, K.; García, R.; Cuevas, E.; Ochoa, H.; Deferrari, G.; Díaz, S.

    2008-02-01

    Three NILU-UV multichannel radiometers have been installed in 1999 at the Argentinian sites of Ushuaia (54S), Marambio (64S) and Belgrano-II (77S) in order to continuously monitor UV radiation, photosynthetically active radiation and total ozone. The measurements were established by INM, Spain in collaboration with FMI, Finland, DNA-IAA, Argentina and CADIC, Argentina to observe and characterize the spatial and temporal evolution of ozone and ultraviolet radiation in the Antarctic region. Special attention has been given to the quality control and quality assurance of the measurements under harsh climatological conditions. The ozone and UV time series of 2000-2006 were calibrated using a polynomial fit for lamp measurements performed every second week all year round. The gaps in these data are minimal, with almost no data missing, and the data products are available from http://www.polarvortex.org in near real time. The data products include the erythemally-weighted UV, UVB and UVA radiation, photosynthetically active radiation (PAR), total ozone (O3) and a cloud parameter (CLT). For UV data, dose rates as well as daily doses are available; from these the maximum measured UV indices (UVI), during 2000-2006, were 12.0, 9.7 and 8.1 at Ushuaia, Marambio and Belgrano-II, respectively.

  7. Understanding diversity patterns in bacterioplankton communities from a sub-Antarctic peatland.

    Science.gov (United States)

    Quiroga, María Victoria; Valverde, Angel; Mataloni, Gabriela; Cowan, Don

    2015-06-01

    Bacterioplankton communities inhabiting peatlands have the potential to influence local ecosystem functions. However, most microbial ecology research in such wetlands has been done in ecosystems (mostly peat soils) of the Northern Hemisphere, and very little is known of the factors that drive bacterial community assembly in other regions of the world. In this study, we used high-throughput sequencing to analyse the structure of the bacterial communities in five pools located in a sub-Antarctic peat bog (Tierra del Fuego, Argentina), and tested for relationships between bacterial communities and environmental conditions. Bacterioplankton communities in peat bog pools were diverse and dominated by members of the Proteobacteria, Actinobacteria, Bacteroidetes and Verrucomicrobia. Community structure was largely explained by differences in hydrological connectivity, pH and nutrient status (ombrotrophic versus minerotrophic pools). Bacterioplankton communities in ombrotrophic pools showed phylogenetic clustering, suggesting a dominant role of deterministic processes in shaping these assemblages. These correlations between habitat characteristics and bacterial diversity patterns provide new insights into the factors regulating microbial populations in peatland ecosystems. PMID:25727763

  8. Flow speed within the Antarctic ice sheet and its controls inferred from satellite observations

    Science.gov (United States)

    Arthern, Robert J.; Hindmarsh, Richard C. A.; Williams, C. Rosie

    2015-07-01

    Accurate dynamical models of the Antarctic ice sheet with carefully specified initial conditions and well-calibrated rheological parameters are needed to forecast global sea level. By adapting an inverse method previously used in electric impedance tomography, we infer present-day flow speeds within the ice sheet. This inversion uses satellite observations of surface velocity, snow accumulation rate, and rate of change of surface elevation to estimate the basal drag coefficient and an ice stiffness parameter that influences viscosity. We represent interior ice motion using a vertically integrated approximation to incompressible Stokes flow. This model represents vertical shearing within the ice and membrane stresses caused by horizontal stretching and shearing. Combining observations and model, we recover marked geographical variations in the basal drag coefficient. Relative changes in basal shear stress are smaller. No simple sliding law adequately represents basal shear stress as a function of sliding speed. Low basal shear stress predominates in central East Antarctica, where thick insulating ice allows liquid water at the base to lubricate sliding. Higher shear stress occurs in coastal East Antarctica, where a frozen bed is more likely. Examining Thwaites glacier in more detail shows that the slowest sliding often coincides with elevated basal topography. Differences between our results and a similar adjoint-based inversion suggest that inversion or regularization methods can influence recovered parameters for slow sliding and finer scales; on broader scales we recover a similar pattern of low basal drag underneath major ice streams and extensive regions in East Antarctica that move by basal sliding.

  9. Antarctic network of lamp-calibrated multichannel radiometers for continuous ozone and uv radiation data

    Directory of Open Access Journals (Sweden)

    A. Redondas

    2008-02-01

    Full Text Available Three NILU-UV multichannel radiometers have been installed in 1999 at the Argentinian sites of Ushuaia (54S, Marambio (64S and Belgrano-II (77S in order to continuously monitor UV radiation, photosynthetically active radiation and total ozone. The measurements were established by INM, Spain in collaboration with FMI, Finland, DNA-IAA, Argentina and CADIC, Argentina to observe and characterize the spatial and temporal evolution of ozone and ultraviolet radiation in the Antarctic region. Special attention has been given to the quality control and quality assurance of the measurements under harsh climatological conditions. The ozone and UV time series of 2000–2006 were calibrated using a polynomial fit for lamp measurements performed every second week all year round. The gaps in these data are minimal, with almost no data missing, and the data products are available from http://www.polarvortex.org in near real time. The data products include the erythemally-weighted UV, UVB and UVA radiation, photosynthetically active radiation (PAR, total ozone (O3 and a cloud parameter (CLT. For UV data, dose rates as well as daily doses are available; from these the maximum measured UV indices (UVI, during 2000–2006, were 12.0, 9.7 and 8.1 at Ushuaia, Marambio and Belgrano-II, respectively.

  10. Assessing the Impact of Antarctic Oscillation on Precipitation Variability over the La Plata River Basin

    Science.gov (United States)

    Rocha, R. M.; Nunes, A.

    2012-12-01

    Although several studies have considered the phase changes of the Antarctic Oscillation (AAO) - the dominant mode of the Southern Hemisphere (SH) extra-tropical circulation - as one of the driven mechanisms in the SH precipitation inter-annual variability, relatively few studies have addressed the AAO phase change impacts on South American precipitation variability. Those studies found that positive (negative) AAO phase reduces (intensifies) precipitation over southeastern South America, and modulates ENSO's influence on that region. During the austral summer, the inter-annual tropical activity intensification (reduction) has been associated with AAO negative (positive) phase, as well as the corresponding variability in the positioning of the subtropical upper-level jet. In this study, the AAO phases were associated with precipitation patterns that affect water supplies for densely cultivated areas in the southeastern South America, more specifically over the La Plata River basin, taking into account the AAO seasonal index and satellite-based precipitation estimates. Changes found in the positioning and intensity of the upper-level jet were also associated with the AAO phases, and ultimately related to precipitation variability.

  11. A gene encoding a new cold-active lipase from an Antarctic isolate of Penicillium expansum.

    Science.gov (United States)

    Mohammed, Suja; Te'o, Junior; Nevalainen, Helena

    2013-08-01

    Cold-active lipases are of significant interest as biocatalysts in industrial processes. We have identified a lipase that displayed activity towards long carbon-chain-p-nitrophenyl substrates (C12-C18) at 25 °C from the culture supernatant of an Antarctic Penicillium expansum strain assigned P. expansum SM3. Zymography revealed a protein band of around 30 kDa with activity towards olive oil. DNA fragments of a lipase gene designated as lipPE were isolated from the genomic DNA of P. expansum SM3 by genomic walking PCR. Subsequently, the complete genomic lipPE gene was amplified using gene-specific primers designed from the 5'- and 3'-regions. Reverse transcription PCR was used to amplify the lipPE cDNA. The deduced amino acid sequence consisted of 285 residues that included a predicted signal peptide. Three peptides identified by LC/MS/MS analysis of the proteins in the culture supernatant of P. expansum were also present in the deduced amino acid sequence of the lipPE gene suggesting that this gene encoded the lipase identified by initial zymogram activity analysis. Full analysis of the nucleotide and the deduced amino acid sequences indicated that the lipPE gene encodes a novel P. expansum lipase. The lipPE gene was expressed in E. coli for further characterization of the enzyme with a view of assessing its suitability for industrial applications. PMID:23779196

  12. Southern Ocean phytoplankton turnover in response to stepwise Antarctic cooling over the past 15 million years.

    Science.gov (United States)

    Crampton, James S; Cody, Rosie D; Levy, Richard; Harwood, David; McKay, Robert; Naish, Tim R

    2016-06-21

    It is not clear how Southern Ocean phytoplankton communities, which form the base of the marine food web and are a crucial element of the carbon cycle, respond to major environmental disturbance. Here, we use a new model ensemble reconstruction of diatom speciation and extinction rates to examine phytoplankton response to climate change in the southern high latitudes over the past 15 My. We identify five major episodes of species turnover (origination rate plus extinction rate) that were coincident with times of cooling in southern high-latitude climate, Antarctic ice sheet growth across the continental shelves, and associated seasonal sea-ice expansion across the Southern Ocean. We infer that past plankton turnover occurred when a warmer-than-present climate was terminated by a major period of glaciation that resulted in loss of open-ocean habitat south of the polar front, driving non-ice adapted diatoms to regional or global extinction. These findings suggest, therefore, that Southern Ocean phytoplankton communities tolerate "baseline" variability on glacial-interglacial timescales but are sensitive to large-scale changes in mean climate state driven by a combination of long-period variations in orbital forcing and atmospheric carbon dioxide perturbations. PMID:27274061

  13. Rock weathering Tendency at Different Stages of Soil—Forming Processes in Fildes Peninsula,Antarctic

    Institute of Scientific and Technical Information of China (English)

    CHENJIE; GONGZITONG

    1996-01-01

    From the view of energy state of material,this paper introduces a concept a concept of weathering potential in carrying out quantitative calculation of the relevant products at different stages of rock-weathering and primary soil-forming processes,elaborates respectively on weathering degree in the bio-weathering layer of rocks and during the formation of soil material and clay,and evaluats the further tendency of weathering in the above-mentioned stages.The authors have discovered that the scales of weathering potential of the materials increase successively in the three stages,which indicates that the products in the above-mentioned three stages must have undergone stronger and stronger weathering in the primitive forming process of soil in Fildes Peninsula,Antarctic.But,Because of relatively weak chemical weathering,it is reasonable that there are much more skeleton grains and little clay in priamry soils in this region.Meanwhile the authors have also verified that the weathering potential of crde rock determines to some extent decrease in the products' weathering potential in the different stages in primary soil-forming,thereby plays an important role in the genesis and development of the primary soil in the studied area.

  14. Antarctic Planetary Testbed (APT): A facility in the Antarctic for research, planning and simulation of manned planetary missions and to provide a testbed for technological development

    Science.gov (United States)

    Ahmadi, Mashid; Bottelli, Alejandro Horacio; Brave, Fernando Luis; Siddiqui, Muhammad Ali

    1988-01-01

    The notion of using Antarctica as a planetary analog is not new. Ever since the manned space program gained serious respect in the 1950's, futurists have envisioned manned exploration and ultimate colonization of the moon and other extraterrestrial bodies. In recent years, much attention has been focused on a permanently manned U.S. space station, a manned Lunar outpost and a manned mission to Mars and its vicinity. When such lofty goals are set, it is only prudent to research, plan and rehearse as many aspects of such a mission as possible. The concept of the Antarctic Planetary Testbed (APT) project is intended to be a facility that will provide a location to train and observe potential mission crews under conditions of isolation and severity, attempting to simulate an extraterrestrial environment. Antarctica has been considered as an analog by NASA for Lunar missions and has also been considered by many experts to be an excellent Mars analog. Antarctica contains areas where the environment and terrain are more similar to regions on the Moon and Mars than any other place on Earth. These features offer opportunities for simulations to determine performance capabilities of people and machines in harsh, isolated environments. The initial APT facility, conceived to be operational by the year 1991, will be constructed during the summer months by a crew of approximately twelve. Between six and eight of these people will remain through the winter. As in space, structures and equipment systems will be modular to facilitate efficient transport to the site, assembly, and evolutionary expansion. State of the art waste recovery/recycling systems are also emphasized due to their importance in space.

  15. Characterising East Antarctic Lithosphere and its Rift Systems using Gravity Inversion

    Science.gov (United States)

    Vaughan, Alan P. M.; Kusznir, Nick J.; Ferraccioli, Fausto; Leat, Phil T.; Jordan, Tom A. R. M.; Purucker, Michael E.; Golynsky, A. V. Sasha; Rogozhina, Irina

    2013-04-01

    Cenozoic ice sheet formation and stability. References Chappell, A.R. & Kusznir, N.J. 2008. Three-dimensional gravity inversion for Moho depth at rifted continental margins incorporating a lithosphere thermal gravity anomaly correction. Geophysical Journal International, 174 (1), 1-13. Ferraccioli, F., Finn, C.A., Jordan, T.A., Bell, R.E., Anderson, L.M. & Damaske, D. 2011. East Antarctic rifting triggers uplift of the Gamburtsev Mountains Nature, 479, 388-392. Golynsky, A.V. & Golynsky, D.A. 2009. Rifts in the tectonic structure of East Antarctica (in Russian). Russian Earth Science Research in Antarctica, 2, 132-162. Vaughan, A.P.M., Kusznir, N.J., Ferraccioli, F. & Jordan, T.A.R.M. 2012. Regional heat-flow prediction for Antarctica using gravity inversion mapping of crustal thickness and lithosphere thinning. Geophysical Research Abstracts, 14, EGU2012-8095.

  16. Did the continent and sea have different temperatures in the northern Antarctic Peninsula during the Middle Eocene?

    Directory of Open Access Journals (Sweden)

    A.L. Cione

    2007-12-01

    Full Text Available The Seymour Island beds include a remarkable representation of the continental flora and fauna and marine fauna of Eocene in southern high latitudes. We suggest that, at least during the deposition of the best sampled unit, the Cucullaea I Allomember of the La Meseta Alloformation in the Seymour Island area, a cold temperate terrestrial environment co-existed with relatively warmer temperatures in the adjacent shallow shelf sea. This is suggested by the fish and invertebrate fauna and could have been due to the presence of warmer waters of a current reaching the region from the north. The temperature drop proposed for the time of deposition of the uppermost part of the La Meseta Formation (Submeseta Allomember appears to correspond to the global drop of the end of the Eocene and beginning of Oligocene and not to the establishment of the Antarctic Circumpolar Current.

  17. The application of PCR for the isolation of a lipase gene from the genomic DNA of an Antarctic microfungus.

    Science.gov (United States)

    Bradner, J Ron; Bell, Philip J L; Te'o, V S Junior; Nevalainen, K M Helena

    2003-12-01

    We successfully isolated a lipase gene (designated lipPA) directly from the genomic DNA of an Antarctic isolate of Penicillium allii using PCR and a suite of degenerate primers specifically designed to target two conserved regions of fungal lipase genes. We applied the biolistic transformation system to successfully integrate the lipPA gene into a heterologous fungal host, Trichoderma reesei, one of the most powerful secretors of extracellular proteins, and induced the transformant to secrete an active lipase into the growth medium. The recombinant lipase had a temperature optimum of 25 degrees C at pH 7.9 and retained greater than 50% of the maximum activity from 10 degrees C to 35 degrees C and over a pH range from 4.0 to 8.5. PMID:13680154

  18. Long-term (1993-2013) changes in macrozooplankton off the Western Antarctic Peninsula

    Science.gov (United States)

    Steinberg, Deborah K.; Ruck, Kate E.; Gleiber, Miram R.; Garzio, Lori M.; Cope, Joseph S.; Bernard, Kim S.; Stammerjohn, Sharon E.; Schofield, Oscar M. E.; Quetin, Langdon B.; Ross, Robin M.

    2015-07-01

    The Western Antarctic Peninsula (WAP) is one of the most rapidly warming regions on Earth, and where a high apex predator biomass is supported in large part by macrozooplankton. We examined trends in summer (January-February) abundance of major taxa of macrozooplankton along the WAP over two decades (1993-2013) and their relationship with environmental parameters (sea ice, atmospheric climate indices, sea surface temperature, and phytoplankton biomass and productivity). Macrozooplankton were collected from the top 120 m of the water column in a mid-Peninsula study region divided into latitudinal (North, South, and Far South) and cross-shelf (coastal, shelf, slope) sub-regions. Trends for krill species included a 5-year cycle in abundance peaks (positive anomalies) for Euphausia superba, but no directional long-term trend, and an increase in Thysanoessa macrura in the North; variability in both species was strongly influenced by primary production 2-years prior. E. crystallorophias abundance was best explained by the Southern Annular Mode (SAM) and Multivariate El Niño Southern Oscillation Index (MEI), and was more abundant in higher ice conditions. The salp Salpa thompsoni and thecosome pteropod Limacina helicina cycled between negative and positive anomalies in the North, but showed increasing positive anomalies in the South over time. Variation in salp and pteropod abundance was best explained by SAM and the MEI, respectively, and both species were more abundant in lower ice conditions. There was a long-term increase in some carnivorous gelatinous zooplankton (polychaete worm Tomopteris spp.) and amphipods. Abundance of Pseudosagitta spp. chaetognaths was closely related to SAM, with higher abundance tied to lower ice conditions. Long-term changes and sub-decadal cycles of WAP macrozooplankton community composition may affect energy transfer to higher trophic levels, and alter biogeochemical cycling in this seasonally productive and sensitive polar ecosystem.

  19. New Cysteine-Rich Ice-Binding Protein Secreted from Antarctic Microalga, Chloromonas sp.

    Science.gov (United States)

    Jung, Woongsic; Campbell, Robert L; Gwak, Yunho; Kim, Jong Im; Davies, Peter L; Jin, EonSeon

    2016-01-01

    Many microorganisms in Antarctica survive in the cold environment there by producing ice-binding proteins (IBPs) to control the growth of ice around them. An IBP from the Antarctic freshwater microalga, Chloromonas sp., was identified and characterized. The length of the Chloromonas sp. IBP (ChloroIBP) gene was 3.2 kb with 12 exons, and the molecular weight of the protein deduced from the ChloroIBP cDNA was 34.0 kDa. Expression of the ChloroIBP gene was up- and down-regulated by freezing and warming conditions, respectively. Western blot analysis revealed that native ChloroIBP was secreted into the culture medium. This protein has fifteen cysteines and is extensively disulfide bonded as shown by in-gel mobility shifts between oxidizing and reducing conditions. The open-reading frame of ChloroIBP was cloned and over-expressed in Escherichia coli to investigate the IBP's biochemical characteristics. Recombinant ChloroIBP produced as a fusion protein with thioredoxin was purified by affinity chromatography and formed single ice crystals of a dendritic shape with a thermal hysteresis activity of 0.4±0.02°C at a concentration of 5 mg/ml. In silico structural modeling indicated that the three-dimensional structure of ChloroIBP was that of a right-handed β-helix. Site-directed mutagenesis of ChloroIBP showed that a conserved region of six parallel T-X-T motifs on the β-2 face was the ice-binding region, as predicted from the model. In addition to disulfide bonding, hydrophobic interactions between inward-pointing residues on the β-1 and β-2 faces, in the region of ice-binding motifs, were crucial to maintaining the structural conformation of ice-binding site and the ice-binding activity of ChloroIBP. PMID:27097164

  20. beta-diversity and species accumulation in antarctic coastal benthos: influence of habitat, distance and productivity on ecological connectivity.

    Directory of Open Access Journals (Sweden)

    Simon F Thrush

    Full Text Available High Antarctic coastal marine environments are comparatively pristine with strong environmental gradients, which make them important places to investigate biodiversity relationships. Defining how different environmental features contribute to shifts in beta-diversity is especially important as these shifts reflect both spatio-temporal variations in species richness and the degree of ecological separation between local and regional species pools. We used complementary techniques (species accumulation models, multivariate variance partitioning and generalized linear models to assess how the roles of productivity, bio-physical habitat heterogeneity and connectivity change with spatial scales from metres to 100's of km. Our results demonstrated that the relative importance of specific processes influencing species accumulation and beta-diversity changed with increasing spatial scale, and that patterns were never driven by only one factor. Bio-physical habitat heterogeneity had a strong influence on beta-diversity at scales 40 km. Our analysis supports the emphasis on the analysis of diversity relationships across multiple spatial scales and highlights the unequal connectivity of individual sites to the regional species pool. This has important implications for resilience to habitat loss and community homogenisation, especially for Antarctic benthic communities where rates of recovery from disturbance are slow, there is a high ratio of poor-dispersing and brooding species, and high biogenic habitat heterogeneity and spatio-temporal variability in primary production make the system vulnerable to disturbance. Consequently, large areas need to be included within marine protected areas for effective management and conservation of these special ecosystems in the face of increasing anthropogenic disturbance.