Antarctic Tardigrada: a first step in understanding molecular operational taxonomic units (MOTUs) and biogeography of cryptic meiofauna

2012 ◽  
Vol 26 (6) ◽  
pp. 526 ◽  
Author(s):  
Paul Czechowski ◽  
Chester J. Sands ◽  
Byron J. Adams ◽  
Cyrille A. D'Haese ◽  
John A. E. Gibson ◽  
...  
Keyword(s):  
Soil Samples ◽  
Term Survival ◽  
Operational Taxonomic Units ◽  
Gene Comparison ◽  
Gene Coi ◽  
Dronning Maud Land ◽  
Antarctic Continent ◽  
The Antarctic ◽  
I Gene

Recent studies have suggested that some resident Antarctic biota are of ancient origin and may have been isolated for millions of years. The phylum Tardigrada, which is part of the Antarctic terrestrial meiofauna, is of particular interest due to an impressive array of biochemical abilities to withstand harsh environmental conditions. Tardigrades are one of the few widespread Antarctic terrestrial animals that have the potential to be used as a model for evolution and biogeography on the Antarctic continent. We isolated 126 individual tardigrades from four geographically isolated soil samples from two remote nunataks in the Sør Rondane Mountains, Dronning Maud Land, Antarctica. We examined genetic variation among individuals utilising three gene regions: cytochrome c oxidase subunit I gene (COI), 18S rDNA (18S), and the wingless (Wg) gene. Comparison of sequences from worldwide and Antarctic tardigrades indicated long-term survival and isolation over glacially dominated periods in ice-free habitats in the Sør Rondane Mountains.

scholarly journals Reproductive performance of the Antarctic tardigrades, Acutuncus antarcticus (Eutardigrada: Hypsibiidae), revived after being frozen for over 30 years and of their offspring

2019 ◽  
Vol 188 (3) ◽  
pp. 839-847
Author(s):  
Megumu Tsujimoto ◽  
Hiroshi Kagoshima ◽  
Hiroshi Kanda ◽  
Kenichi Watanabe ◽  
Satoshi Imura
Keyword(s):  
Reproductive Performance ◽  
First Generation ◽  
Dna Analysis ◽  
Term Survival ◽  
Long Term Survival ◽  
Genetic Types ◽  
Genetic Sequences ◽  
The Antarctic ◽  
Generation Offspring

Abstract Studies on the long-term survival of animals often focus on the specific instance of survival of animals only, and descriptions of subsequent reproduction are generally not reported. In this study, we recorded the reproductive performance of the first-generation offspring of the resuscitated individual (SB-1) and the hatchling of the resuscitated egg (SB-3) of the Antarctic tardigrade, Acutuncus antarcticus, after being frozen for 30.5 years. By providing further detailed description of the reproduction of SB-1 and SB-3 after revival, and then comparing the reproductive performance with that of their first-generation offspring, the possible indications of the damage accrued during the long-term preservation in SB-1 and SB-3 were more specifically detected. Additionally, the DNA analysis revealed two distinctively different mitochondrial genetic sequences of A. antarcticus between the SB strains and the LSW strain. The observed differences in some of the reproductive parameters between the two genetic types suggested a possible relationship between the life-history traits and genetic type in the species A. antarcticus. Further experiments using the SB-1 and SB-3 strains reared for a long period to exclude the instant effect of preservation are expected to improve our understanding of the mechanisms underlying the long-term survival of animals.

Exhumation and performance of an Antarctic composite barrier system after 4 years exposure

2020 ◽  
Vol 57 (8) ◽  
pp. 1130-1152 ◽  
Author(s):  
R.S. McWatters ◽  
R.K. Rowe ◽  
V. Di Battista ◽  
B. Sfiligoj ◽  
D. Wilkins ◽  
...  
Keyword(s):  
High Density Polyethylene ◽  
Soil Samples ◽  
Composite Liner ◽  
Subgrade Soil ◽  
And Performance ◽  
Long Term Performance ◽  
Term Performance ◽  
The Antarctic ◽  
Coarse Gravel

An Antarctic biopile using a composite liner (high-density polyethylene geomembrane (GMB) over a geosynthetic clay liner (GCL)) was constructed on a coarse granular subgrade to contain hydrocarbon-contaminated soil and leachate. The soil was remediated after 4 years and the biopile was decommissioned. The liner was exhumed to assess the properties and performance of the GMB and GCL. There was no significant change in the GMB index properties. Although cobbles and coarse gravel of the subgrade had left indentations in the GMB, implying tensile strains that could impact long-term performance, there were no holes. There was significant variability in the hydration of the GCL (from 10% to 220%) and in the underlying subgrade soil water content (from 5% to 30%). This reflects the complexity of the subgrade and groundwater flow in the Antarctic environment. The exhumed GCL specimens had low hydraulic conductivity (1 × 10−11 to 7 × 10−11 m/s) at 13 kPa. Soil samples from below the composite liner showed no detectable hydrocarbons and confirmed no migration through the barrier. It is concluded that the composite barrier contained the leachate and biopile soil over the 4 years in service in the extreme Antarctic conditions.

scholarly journals Biogeography of terrestrial cyanobacteria from Antarctic ice-free areas

2010 ◽  
Vol 51 (56) ◽  
pp. 171-177 ◽  
Author(s):  
Z. Namsaraev ◽  
M.-J. Mano ◽  
R. Fernandez ◽  
Annick Wilmotte
Keyword(s):  
Rrna Gene ◽  
Distribution Analysis ◽  
Operational Taxonomic Units ◽  
Terrestrial Cyanobacteria ◽  
Victoria Land ◽  
Low Degree ◽  
Range Transport ◽  
Antarctic Continent ◽  
The Antarctic ◽  
Further Development

AbstractCyanobacteria inhabit the Antarctic continent and have even been observed in the most southerly ice-free areas of Antarctica (86–87° S). The highest molecular diversity of cyanobacterial communities was found in the areas located between 70° S and 80° S. Further south and further north from this zone, the diversity abruptly decreased. Seventy-nine per cent (33 of 42 operational taxonomic units) of Antarctic terrestrial cyanobacteria have a cosmopolitan distribution. Analysis of the sampling efforts shows that only three regions (southern Victoria Land, the Sør Rondane Mountains and Alexander Island) have been particularly well studied, while other areas did not receive enough attention. Although cyanobacteria possess a capacity for long-range transport, regional populations in Antarctic ice-free areas seem to exist. The cyanobacterial communities of the three most intensively studied regions, separated from each other by a distance of 3000–3400 km, had a low degree of similarity with each other. Further development of microbial biogeography demands a standardized approach. For this purpose, as a minimal standard, we suggest using the sequence of cyanobacterial 16S rRNA gene between Escherichia coli positions 405 and 780.

scholarly journals Evaluation of CloudSat snowfall rate profiles by a comparison with in situ micro-rain radar observations in East Antarctica

2019 ◽  
Vol 13 (3) ◽  
pp. 943-954 ◽  
Author(s):  
Florentin Lemonnier ◽  
Jean-Baptiste Madeleine ◽  
Chantal Claud ◽  
Christophe Genthon ◽  
Claudio Durán-Alarcón ◽  
...  
Keyword(s):  
Climate Models ◽  
Water Reservoir ◽  
Dronning Maud Land ◽  
Antarctic Continent ◽  
Unknown Area ◽  
The Antarctic ◽  
Vertical Level ◽  
Rain Radar ◽  
Precipitation Events

Abstract. The Antarctic continent is a vast desert and is the coldest and the most unknown area on Earth. It contains the Antarctic ice sheet, the largest continental water reservoir on Earth that could be affected by the current global warming, leading to sea level rise. The only significant supply of ice is through precipitation, which can be observed from the surface and from space. Remote-sensing observations of the coastal regions and the inner continent using CloudSat radar give an estimated rate of snowfall but with uncertainties twice as large as each single measured value, whereas climate models give a range from half to twice the space–time-averaged observations. The aim of this study is the evaluation of the vertical precipitation rate profiles of CloudSat radar by comparison with two surface-based micro-rain radars (MRRs), located at the coastal French Dumont d'Urville station and at the Belgian Princess Elisabeth station located in the Dronning Maud Land escarpment zone. This in turn leads to a better understanding and reassessment of CloudSat uncertainties. We compared a total of four precipitation events, two per station, when CloudSat overpassed within 10 km of the station and we compared these two different datasets at each vertical level. The correlation between both datasets is near-perfect, even though climatic and geographic conditions are different for the two stations. Using different CloudSat and MRR vertical levels, we obtain 10 km space-scale and short-timescale (a few seconds) CloudSat uncertainties from −13 % up to +22 %. This confirms the robustness of the CloudSat retrievals of snowfall over Antarctica above the blind zone and justifies further analyses of this dataset.

scholarly journals On the Long-Term Climate Memory in the Surface Air Temperature Records over Antarctica: A Nonnegligible Factor for Trend Evaluation

2015 ◽  
Vol 28 (15) ◽  
pp. 5922-5934 ◽  
Author(s):  
Naiming Yuan ◽  
Minghu Ding ◽  
Yan Huang ◽  
Zuntao Fu ◽  
Elena Xoplaki ◽  
...  
Keyword(s):  
White Noise ◽  
Surface Air Temperature ◽  
Fluctuation Analysis ◽  
The West ◽  
Weather System ◽  
Air Temperatures ◽  
Antarctic Continent ◽  
Temperature Records ◽  
The Antarctic

Abstract In this study, observed temperature records of 12 stations from Antarctica island, coastline, and continental areas are analyzed by means of detrended fluctuation analysis (DFA). After Monte Carlo significance tests, different long-term climate memory (LTM) behaviors are found: temperatures from coastal and island stations are characterized by significant long-term climate memory whereas temperatures over the Antarctic continent behave more like white noise, except for the Byrd station, which is located in the West Antarctica. It is argued that the emergence of LTM may be dominated by the interactions between local weather system and external slow-varying systems (ocean), and therefore the different LTM behaviors between temperatures over the Byrd station and that over other continental stations can be considered as a reflection of the different climatic environments between West and East Antarctica. By calculating the trend significance with the effect of LTM taken into account, and further comparing the results with those obtained from assumptions of autoregressive (AR) process and white noise, it is found that 1) most of the Antarctic stations do not show any significant trends over the past several decades, and 2) more rigorous trend evaluation can be obtained if the effect of LTM is considered. Therefore, it is emphasized that for air temperatures over Antarctica, especially for the Antarctica coastline, island, and the west continental areas, LTM is nonnegligible for trend evaluation.

Synoptic situations causing high precipitation rates on the Antarctic plateau: observations from Kohnen Station, Dronning Maud Land

2006 ◽  
Vol 18 (2) ◽  
pp. 279-288 ◽  
Author(s):  
Gerit Birnbaum ◽  
Ralf Brauner ◽  
Hinnerk Ries
Keyword(s):  
Large Scale ◽  
Ice Core ◽  
Mean Value ◽  
Cloud Formation ◽  
Heavy Snowfall ◽  
Greenwich Meridian ◽  
Dronning Maud Land ◽  
High Precipitation ◽  
The Antarctic

Kohnen Station (75°S, 0°E, 2892 m) is one of the two drilling sites of the European Project for Ice Coring in Antarctica. Snow falls at Kohnen only a few times a year with comparatively high precipitation rates of 1 mm to over 5 mm water equivalent per event. These events contribute considerably to the total annual accumulation of which the long-term mean value is 62 mm water equivalent per year. For ice core interpretation, it is important to understand synoptic processes leading to such high precipitation rates. Our investigation is based on visually observed periods of heavy snowfall at Kohnen during summer campaigns since 2001/2002. The corresponding synoptic situations can be grouped into three categories. Category I is where occluding fronts of eastward-moving low pressure systems reach the plateau, a fairly frequent occurrence. Category II is where lows or secondary lows formed east of the Greenwich Meridian move to the west (retrograde movement), and frontal clouds influence the plateau. In Category III, large-scale lifting processes (due to an upper air low west of Kohnen Station) lead to cloud formation over the plateau of Dronning Maud Land.

scholarly journals Neumayer III and Kohnen Station in Antarctica operated by the Alfred Wegener Institute

2016 ◽  
Vol 2 ◽  
Author(s):  
Christine Wesche ◽  
Rolf Weller ◽  
Gert König-Langlo ◽  
Tanja Fromm ◽  
Alfons Eckstaller ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Shelf ◽  
Deep Drilling ◽  
Research Activities ◽  
Starting Point ◽  
Air Chemistry ◽  
Dronning Maud Land ◽  
Core Project ◽  
The Antarctic

The Alfred Wegener Institute operates two stations in Dronning Maud Land, Antarctica. The German overwintering station Neumayer III is located on the Ekström Ice Shelf at 70°40’S and 08°16’W and is the logistics base for three long-term observatories (meteorology, air chemistry and geophysics) and nearby research activities. Due to the vicinity to the coast (ca. 20 km from the ice shelf edge), the Neumayer III Station is the junction for many German Antarctic expeditions, especially as the starting point for the supply traverse for the second German station Kohnen.The summer station Kohnen is located about 600 km from the coast and 750 km from Neumayer III Station on the Antarctic plateau at 75°S and 00°04’E. It was erected as the base for the deep-drilling ice core project, which took place between 2001 and 2006. Since then Kohnen Station is used as a logistics base for different research projects.

scholarly journals Antarctic climate variability at regional and continental scales over the last 2,000 years

2017 ◽  
Author(s):  
Barbara Stenni ◽  
Mark A. J. Curran ◽  
Nerilie J. Abram ◽  
Anais Orsi ◽  
Sentia Goursaud ◽  
...  
Keyword(s):  
Working Group ◽  
Ice Core ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Temperature Reconstructions ◽  
Temperature Scaling ◽  
Antarctic Continent ◽  
Cooling Trend ◽  
The Antarctic

Abstract. Climate trends in the Antarctic region remain poorly characterised, owing to the brevity and scarcity of direct climate observations and the large magnitude of interannual to decadal-scale climate variability. Here, within the framework of the PAGES Antarctica 2k working group, we build an enlarged database of ice core water stable isotope records from Antarctica, consisting of 112 records. We produce both unweighted and weighted isotopic (δ18O) composites and temperature reconstructions since 0 CE, binned at 5 and 10-year resolution, for 7 climatically-distinct regions covering the Antarctic continent. Following earlier work of the Antarctica 2k working group, we also produce composites and reconstructions for the broader regions of East Antarctica, West Antarctica, and the whole continent. We use three methods for our temperature reconstructions: i) a temperature scaling based on the δ18O-temperature relationship output from an ECHAM5-wiso model simulation nudged to ERA-interim atmospheric reanalyses from 1979 to 2013, and adjusted for the West Antarctic Ice Sheet region to borehole temperature data; ii) a temperature scaling of the isotopic normalized anomalies to the variance of the regional reanalysis temperature and iii) a composite-plus-scaling approach used in a previous continental scale reconstruction of Antarctic temperature since 1 CE but applied to the new Antarctic ice core database. Our new reconstructions confirm a significant cooling trend from 0 to 1900 CE across all Antarctic regions where records extend back into the 1st millennium, with the exception of the Wilkes Land coast and Weddell Sea coast regions. Within this long-term cooling trend from 0–1900 CE we find that the warmest period occurs between 300 and 1000 CE, and the coldest interval from 1200 to 1900 CE. Since 1900 CE, significant warming trends are identified for the West Antarctic Ice Sheet, the Dronning Maud Land coast and the Antarctic Peninsula regions, and these trends are robust across the distribution of records that contribute to the unweighted isotopic composites and also significant in the weighted temperature reconstructions. Only for the Antarctic Peninsula is this most recent century-scale trend unusual in the context of natural variability over the last 2000-years. However, projected warming of the Antarctic continent during the 21st Century may soon see significant and unusual warming develop across other parts of the Antarctic continent. The extended Antarctica 2k ice core isotope database developed by this working group opens up many avenues for developing a deeper understanding of the response of Antarctic climate to natural and anthropogenic climate forcings. The first long-term quantification of regional climate in Antarctica presented herein is a basis for data-model comparison and assessments of past, present and future driving factors of Antarctic climate.

scholarly journals Antarctic Atmospheric River Climatology and Impacts

2020 ◽  
Author(s):  
Jonathan Wille ◽  
Vincent Favier ◽  
Irina V. Gorodetskaya ◽  
Cécile Agosta ◽  
Jai Chowdhry Beeman ◽  
...  
Keyword(s):  
Mass Balance ◽  
Surface Mass Balance ◽  
Ice Shelf ◽  
Surface Mass ◽  
Atmospheric Rivers ◽  
Atmospheric River ◽  
Dronning Maud Land ◽  
Antarctic Continent ◽  
Surface Melt ◽  
The Antarctic

<p>Atmospheric rivers, broadly defined as narrow yet long bands of strong horizontal vapor transport typically imbedded in a low level jet ahead of a cold front of an extratropical cyclone, provide a sub-tropical connection to the Antarctic continent and are observed to significantly impact the affected region’s surface mass balance over short, extreme events. When an atmospheric river makes landfall on the Antarctic continent, their signature is clearly observed in increased downward longwave radiation, cloud liquid water content, surface temperature, snowfall, surface melt, and moisture transport.</p><p>Using an atmospheric river detection algorithm designed for Antarctica and regional climate simulations from MAR, we created a climatology of atmospheric river occurrence and their associated impacts on surface melt and snowfall. Despite their rarity of occurrence over Antarctica (maximum frequency of ~1.5% over a given point), they have produced significant impacts on melting and snowfall processes. From 1979-2017, atmospheric rivers landfalls and their associated radiative flux anomalies and foehn winds accounted for around 40% of the total summer surface melt on the Ross Ice Shelf (approaching 100% at higher elevations in Marie Byrd Land) and 40-80% of total winter surface melt on the ice shelves along the Antarctic Peninsula. On the other side of the continent in East Antarctica, atmospheric rivers have a greater influence on annual snowfall variability. There atmospheric rivers are responsible for 20-40% of annual snowfall with localized higher percentages across Dronning Maud Land, Amery Ice Shelf, and Wilkes Land.</p><p>Atmospheric river landfalls occur within a highly amplified polar jet pattern and often are found in the entrance region of a blocking ridge. Therefore, atmospheric river variability is connected with atmospheric blocking variability over the Southern Ocean. There has been a significant increase in atmospheric river activity over the Amundsen-Bellingshausen sea and coastline and into Dronning Maud Land region from 1980-2018. Meanwhile, there is a significant decreasing trend in the region surrounding Law Dome. Our results suggest that atmospheric rivers play a significant role in the Antarctic surface mass balance, and that any future changes in atmospheric blocking or tropical-polar teleconnections may have significant impacts on future surface mass balance projections.</p>

scholarly journals A Voyage Towards the South Pole

1973 ◽  
Vol 26 (3) ◽  
pp. 373-377
Keyword(s):  
David Lewis ◽  
South Pole ◽  
The South ◽  
Palmer Station ◽  
Antarctic Continent ◽  
The Antarctic ◽  
Term Objective ◽  
The U.S ◽  
Lewis A

Dr. David Lewis, a Fellow of this Institute and occasional contributor to the Journal, arrived at Palmer Station in the Antarctic, under jury rig, on 29 January having left Sydney on 20 October 1972 and stopped twenty-four hours at Stewart Island, N.Z., on the way. His long-term objective is to circumnavigate the Antarctic Continent, single-handed. He was twice capsized, in the course of which his gloves disappeared which resulted in badly frost-bitten fingers. After two months day and night in insulated boots, the warmth in the U.S. base when he arrived made his feet balloon and crack.

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