scholarly journals Polar endoliths – an anti-correlation of climatic extremes and microbial biodiversity

2002 ◽  
Vol 1 (4) ◽  
pp. 305-310 ◽  
Author(s):  
Charles S. Cockell ◽  
Christopher P. McKay ◽  
Christopher Omelon
Keyword(s):  
Biological Diversity ◽  
High Arctic ◽  
Physical Structure ◽  
Environmental Stresses ◽  
The Arctic ◽  
Dry Valleys ◽  
Freeze Thaw ◽  
Devon Island ◽  
Order Of Magnitude ◽  
The Antarctic

We examined the environmental stresses experienced by cyanobacteria living in endolithic gneissic habitats in the Haughton impact structure, Devon Island, Canadian High Arctic (75° N) and compared them with the endolithic habitat at the opposite latitude in the Dry Valleys of Antarctica (76° S). In the Arctic during the summer, there is a period for growth of approximately 2.5 months when temperatures rise above freezing. During this period, freeze–thaw can occur during the diurnal cycle, but freeze–thaw excursions are rare within higher-frequency temperature changes on the scale of minutes, in contrast with the Antarctic Dry Valleys. In the Arctic location rainfall of approximately 3 mm can occur in a single day and provides moisture for endolithic organisms for several days afterwards. This rainfall is an order of magnitude higher than that received in the Dry Valleys over 1 year. In the Dry Valleys, endolithic communities may potentially receive higher levels of ultraviolet radiation than the Arctic location because ozone depletion is more extreme. The less extreme environmental stresses experienced in the Arctic are confirmed by the presence of substantial epilithic growth, in contrast to the Dry Valleys. Despite the more extreme conditions experienced in the Antarctic location, the diversity of organisms within the endolithic habitat, which includes lichen and eukaryotic algal components, is higher than observed at the Arctic location, where genera of cyanobacteria dominate. The lower biodiversity in the Arctic may reflect the higher water flow through the rocks caused by precipitation and the more heterogeneous physical structure of the substrate. The data illustrate an instance in which extreme climate is anti-correlated with microbial biological diversity.

scholarly journals Metagenomic Analysis of Stress Genes in Microbial Mat Communities from Antarctica and the High Arctic

2011 ◽  
Vol 78 (2) ◽  
pp. 549-559 ◽  
Author(s):  
Thibault Varin ◽  
Connie Lovejoy ◽  
Anne D. Jungblut ◽  
Warwick F. Vincent ◽  
Jacques Corbeil
Keyword(s):  
High Arctic ◽  
Environmental Stresses ◽  
The Arctic ◽  
Functional Responses ◽  
Protein Coding ◽  
Content Type ◽  
Stress Genes ◽  
Cyanobacterial Genes ◽  
Shock Proteins ◽  
The Antarctic

ABSTRACTPolar and alpine microbial communities experience a variety of environmental stresses, including perennial cold and freezing; however, knowledge of genomic responses to such conditions is still rudimentary. We analyzed the metagenomes of cyanobacterial mats from Arctic and Antarctic ice shelves, using high-throughput pyrosequencing to test the hypotheses that consortia from these extreme polar habitats were similar in terms of major phyla and subphyla and consequently in their potential responses to environmental stresses. Statistical comparisons of the protein-coding genes showed similarities between the mats from the two poles, with the majority of genes derived fromProteobacteriaandCyanobacteria; however, the relative proportions differed, with cyanobacterial genes more prevalent in the Antarctic mat metagenome. Other differences included a higher representation ofActinobacteriaandAlphaproteobacteriain the Arctic metagenomes, which may reflect the greater access to diasporas from both adjacent ice-free lands and the open ocean. Genes coding for functional responses to environmental stress (exopolysaccharides, cold shock proteins, and membrane modifications) were found in all of the metagenomes. However, in keeping with the greater exposure of the Arctic to long-range pollutants, sequences assigned to copper homeostasis genes were statistically (30%) more abundant in the Arctic samples. In contrast, more reads matching the sigma B genes were identified in the Antarctic mat, likely reflecting the more severe osmotic stress during freeze-up of the Antarctic ponds. This study underscores the presence of diverse mechanisms of adaptation to cold and other stresses in polar mats, consistent with the proportional representation of major bacterial groups.

scholarly journals Arctic tidal characteristics at Eureka (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006/07: seasonal and longitudinal variations, migrating and non-migrating tides

2009 ◽  
Vol 27 (3) ◽  
pp. 1153-1173 ◽  
Author(s):  
A. H. Manson ◽  
C. E. Meek ◽  
T. Chshyolkova ◽  
X. Xu ◽  
T. Aso ◽  
...  
Keyword(s):  
High Arctic ◽  
Early Summer ◽  
Planetary Waves ◽  
Diurnal Tide ◽  
The Arctic ◽  
Meteor Radar ◽  
Atmospheric Propagation ◽  
Wave Numbers ◽  
The Antarctic ◽  
Abstract Operation

Abstract. Operation of a Meteor Radar at Eureka, Ellesmere Island (80° N, 86° W) began in February 2006. The first 12 months of wind data (82–97 km) are combined with winds from the Adventdalen, Svalbard Island (78° N, 16° E) Meteor Radar to provide the first contemporaneous longitudinally spaced observations of mean winds, tides and planetary waves at such high Arctic latitudes. Unique polar information on diurnal non-migrating tides (NMT) is provided, as well as complementary information to that existing for the Antarctic on the semidiurnal NMT. Zonal and meridional monthly mean winds differed significantly between Canada and Norway, indicating the influence of stationary planetary waves (SPW) in the Arctic mesopause region. Both diurnal (D) and semi-diurnal (SD) winds also demonstrated significantly different magnitudes at Eureka and Svalbard. Typically the D tide was larger at Eureka and the SD tide was larger at Svalbard. Tidal amplitudes in the Arctic were also generally larger than expected from extrapolation of high mid-latitude data. For example time-sequences from ~90 km showed D wind oscillations at Eureka of 30 m/s in February–March, and four day bursts of SD winds at Svalbard reached 40 m/s in June 2006. Fitting of wave numbers for the migrating and non-migrating tides (MT, NMT) successfully determines dominant tides for each month and height. For the diurnal tide, NMT with s=0, +2 (westward) dominate in non-summer months, while for the semi-diurnal tide NMT with s=+1, +3 occur most often during equinoctial or early summer months. These wave numbers are consistent with stationary planetary wave (SPW)-tidal interactions. Assessment of the global topographic forcing and atmospheric propagation of the SPW (S=1, 2) suggests these winter waves of the Northern Hemisphere are associated with the 78–80° N diurnal NMT, but that the SPW of the Southern Hemisphere winter have little influence on the summer Arctic tidal fields. In contrast the large SPW and NMT of the Arctic winter may be associated, consistent with Antarctic observations, with the observed occurrence of the semidiurnal NMT in the Antarctic summer.

Decoupled responses of soil bacteria and their invertebrate consumer to warming, but not freeze-thaw cycles, in the Antarctic Dry Valleys

2017 ◽  
Vol 20 (10) ◽  
pp. 1242-1249 ◽  
Author(s):  
Matthew A. Knox ◽  
Walter S. Andriuzzi ◽  
Heather N. Buelow ◽  
Cristina Takacs-Vesbach ◽  
Byron J. Adams ◽  
...  
Keyword(s):  
Soil Bacteria ◽  
Dry Valleys ◽  
Freeze Thaw ◽  
The Antarctic

A new hexactinellid sponge from the Cretaceous of Devon Island, Canadian High Arctic

2007 ◽  
Vol 44 (9) ◽  
pp. 1235-1242 ◽  
Author(s):  
J Keith Rigby ◽  
Karen Chin ◽  
John D Bloch ◽  
Justin S Tweet
Keyword(s):  
New Genus ◽  
High Arctic ◽  
The Arctic ◽  
Canadian High Arctic ◽  
Light Regimes ◽  
Fine Grained ◽  
Devon Island ◽  
Dermal Layer ◽  
Hexactinellid Sponge ◽  
Fish Teeth

Over 20 specimens of the new genus and species Nunavutospongia irregulara, an irregular stump-like to columnar, or fan- to blade-shaped, hexactinosid hexactinellid sponge, have been recovered from exposures of the Upper Cretaceous upper Kanguk Formation on Devon Island, Nunavut Territory, in the Canadian High Arctic. The species and genus are characterized by dermal surfaces with prominent radial, irregularly vertical, rib-like flanges that have a single linear series of separated oscula perforating their rounded crests. The thin, but persistent dermal layer of fused hexactine-based spicules has rays thicker than those of the similarly fused endosomal, quadrangularly arranged, hexactines of the principal skeleton. Ostia of coarse exhalant canals, and finer inhalant canals, are extensively and uniformly developed, but irregularly placed, in the dermal layer. A thin, less prominent, gastral layer of thickened spicules lines the short, internally tapered spongocoel openings. The skeleton exposed in the commonly upward-arcuate base of each sponge has a radiate structure that does not have significant ostia. The new genus is tentatively included in the Family Cribrospongiidae Roemer, 1864, within the Order Hexactinosa Schrammen, 1903. The specimens were found in unconsolidated fine-grained glauconitic sediments along with other fossils such as fish teeth, bird bones, lingulids, coprolites, and wood. The sedimentology, stratigraphic context, and co-occurrence with fossil wood suggest that these sponges inhabited the neritic zone. As such, they would have been subject to polar light regimes, because paleogeographic reconstructions indicate that Devon Island was above the Arctic Circle during the Late Cretaceous. The distribution of the specimens suggests that they were solitary sponges that used their arcuate bases to colonize sandy substrates or biotic debris.

Ice thickness measurements and their implications with respect to past and present ice volumes in the Canadian High Arctic ice caps

1977 ◽  
Vol 14 (12) ◽  
pp. 2697-2705 ◽  
Author(s):  
R. M. Koerner
Keyword(s):  
High Arctic ◽  
Snow Accumulation ◽  
The Arctic ◽  
Pronounced Difference ◽  
Baffin Bay ◽  
Ice Caps ◽  
Devon Island ◽  
East And West ◽  
Axel Heiberg Island ◽  
Arctic Ice

The main ice caps on Devon Island, central and northeast Ellesmere Island, and Axel Heiberg Island were sounded using a 620 MHz radar. Ice depths were found to be generally between 300 and 800 m. The bedrock topography is everywhere very irregular. There is a pronounced difference between the thickness, and hence volume, of ice on the east and west sides of the Central Ellesmere and Devon ice caps. The greater thickness on the east sides is attributed to much higher snow accumulation rates there and it is calculated that the asymmetry between the east and west sides began to develop some 8000 years ago. The greater thickness of ice on the ice caps facing Baffin Bay must be considered in any derivation of the dimensions of the Wisconsin ice sheet from maps of isostatic rebound in the Queen Elizabeth Islands. Some of the northwest–southeast tilt of strandlines on Devon and Southern Ellesmere islands can be attributed to the suppression of rebound by these thick ice masses. It is inferred, from the greater symmetry of ice caps in Northern Ellesmere and to a lesser extent Axel Heiberg Island, that the Arctic Ocean is a much less effective moisture source than Baffin Bay.

scholarly journals Robert McCormick and the circumstances of his Arctic fossil collection, 1852–1853

2020 ◽  
Vol 47 (2) ◽  
pp. 286-301
Author(s):  
Philip Stone
Keyword(s):  
Natural History ◽  
Canadian Arctic ◽  
The Arctic ◽  
Polar Regions ◽  
Royal Navy ◽  
History Museum ◽  
Northwest Passage ◽  
Devon Island ◽  
The Antarctic ◽  
Personal Collection

The Royal Navy surgeon Robert McCormick (1800–1890) took part in three mid-nineteenth century British Polar expeditions, two to the Arctic and one to the Antarctic. Of the two Arctic voyages, the first was to Spitsbergen (in today's Svalbard) in 1827; the second from 1852 to 1853, was one of the expeditions dispatched to search for the missing ships commanded by Sir John Franklin that had set out in 1845 to navigate a “Northwest Passage” through the islands of the Canadian Arctic. The Svalbard expedition was formative in developing McCormick's interest in the Polar regions, with the likely highlight of his career being his subsequent participation in the Antarctic expedition of 1839–1843 led by James Clark Ross. Throughout these expeditions, McCormick collected natural history specimens, principally in the fields of ornithology and geology. Many of the geological specimens he retained in a personal collection which passed to what is now the Natural History Museum, London, on his death in 1890. This collection includes rock specimens from Svalbard and Baffin Bay, and a substantial number of Silurian fossils (mostly brachiopods) from Beechey Island and Devon Island in the Canadian Arctic. The fossil collection was the largest of several assembled during the successive expeditions sent out in search of Franklin, but is one of those that has received no subsequent attention. That omission was largely due to McCormick's own scientific shortcomings and persisted despite his determined efforts to promote himself as a serious scientific naturalist and Arctic authority.

scholarly journals Measurements of Atmospheric Variability during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition

2021 ◽  
Author(s):  
Julia Schmale ◽  
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
High Arctic ◽  
Physical Structure ◽  
Surface Energy Budget ◽  
Arctic Climate ◽  
Cloud Formation ◽  
The Arctic ◽  
Atmospheric Variability ◽  
Atmospheric Measurements

<p>The MOSAiC expedition was designed to better understand the local and remote processes influencing the Arctic climate system. The Arctic is warming two to three times faster than the global average, a process known as Arctic amplification. One of the most significant consequences is the retreat of sea ice, which has already diminished by roughly 40 % since satellite measurements began. The Arctic atmospheric, marine and terrestrial changes have important effects on local processes, such as moisture sources, cloud formation, radiative and energy transfer, amongst other. They also have the potential to induce changes to large-scale circulation, which can impact the mid-latitudes of Eurasia and North America.    </p><p>Between September 2019 and October 2020 the MOSAiC expedition performed a large number of atmospheric measurements in the high Arctic, drifting most of the time with the sea ice. Instrumentation was operated from the icebreaker Polarstern (Alfred Wegener Institute), on the sea ice and on flying platforms. Observations covered generally: (i) the atmospheric physical structure (e.g., temperature, humidity, wind speed and direction profiles) with radio soundings, ground-based remote sensing, as well as towers; (ii) clouds and precipitation with a host of lidars, radars and radiometers, as well as distrometers and specific hydrometeor observations; (iii) aerosols and trace gases with real-time measurements as well as offline techniques for chemical and microphysical properties; and (iv) the surface energy budget with measurements of radiation, turbulent fluxes and conductive fluxes.  </p><p>The year-round measurements allow for the study of atmospheric variability during the annual cycle with the important processes of sea ice freeze-up and melting. Other event-based features, such as warm air mass intrusions, cyclones, storms, and lead opening, were studied in detail to understand the implications of these processes for the Arctic system. MOSAiC observations are in addition contributing to the evaluation of satellite-based observations such as radiation fluxes or cloud properties, as well as to the evaluation and improvement of numerical simulations, ranging from simpler box to complex Earth System Models.  </p><p>This presentation will provide an overview of the first atmospheric observational results during MOSAiC.</p>

Physical structure of epishelf lakes of the southern Bunger Hills, East Antarctica

2002 ◽  
Vol 14 (3) ◽  
pp. 253-261 ◽  
Author(s):  
JOHN A.E. GIBSON ◽  
DALE T. ANDERSEN
Keyword(s):  
Saline Water ◽  
Physical Structure ◽  
East Antarctica ◽  
The Other ◽  
The Arctic ◽  
Freshwater Input ◽  
Ice Shelves ◽  
S 100 ◽  
The Antarctic ◽  
Freshwater Environments

Epishelf lakes, positioned between ice-free areas and floating ice shelves or glaciers, are unusual tidal, but largely freshwater, environments found in both the Arctic and the Antarctic. The greatest concentration of these lakes is in the Bunger Hills, East Antarctica (66°S, 100°E). We present and discuss temperature and salinity profiles for five epishelf lakes from this region, most of which show unusual properties. White Smoke Lake is fresh and cold (<0.1°C) throughout; Lake Pol’anskogo has two basins, one fresh and cold, the other saline and warm; ‘Southern’ Lake is cold and saline at depth; Transkriptsii Gulf has a deep, warm saline layer; and ‘Northern’ Lake is relatively warm throughout. The structures of these lakes can be explained in terms of a simple model in which the isolated saline water evident in three of the lakes entered the basins through the connection to the marine waters during periods of reduced freshwater input. By dating these marine incursions, periods of reduced melt, presumably due to colder temperatures, can be determined.

Summer phytoplankton of the northern Barents Sea (75–80º N)

2019 ◽  
pp. 8-19
Author(s):  
Larisa A. Pautova ◽  
Vladimir A. Silkin ◽  
Marina D. Kravchishina ◽  
Valeriy G. Yakubenko ◽  
Anna L. Chultsova
Keyword(s):  
Barents Sea ◽  
Weighted Average ◽  
Arctic Basin ◽  
High Arctic ◽  
Alexandrium Tamarense ◽  
Warm Water ◽  
The Arctic ◽  
Absolute Maximum ◽  
Deep Trench ◽  
Maximum Biomass

The structure of the summer planktonic communities of the Northern part of the Barents sea in the first half of August 2017 were studied. In the sea-ice melting area, the average phytoplankton biomass producing upper 50-meter layer of water reached values levels of eutrophic waters (up to 2.1 g/m3). Phytoplankton was presented by diatoms of the genera Thalassiosira and Eucampia. Maximum biomass recorded at depths of 22–52 m, the absolute maximum biomass community (5,0 g/m3) marked on the horizon of 45 m (station 5558), located at the outlet of the deep trench Franz Victoria near the West coast of the archipelago Franz Josef Land. In ice-free waters, phytoplankton abundance was low, and the weighted average biomass (8.0 mg/m3 – 123.1 mg/m3) corresponded to oligotrophic waters and lower mesotrophic waters. In the upper layers of the water population abundance was dominated by small flagellates and picoplankton from, biomass – Arctic dinoflagellates (Gymnodinium spp.) and cold Atlantic complexes (Gyrodinium lachryma, Alexandrium tamarense, Dinophysis norvegica). The proportion of Atlantic species in phytoplankton reached 75%. The representatives of warm-water Atlantic complex (Emiliania huxleyi, Rhizosolenia hebetata f. semispina, Ceratium horridum) were recorded up to 80º N, as indicators of the penetration of warm Atlantic waters into the Arctic basin. The presence of oceanic Atlantic species as warm-water and cold systems in the high Arctic indicates the strengthening of processes of “atlantificacion” in the region.

A survey of mycorrhizal plants on Truelove Lowland, Devon Island, N.W.T., Canada

1990 ◽  
Vol 68 (9) ◽  
pp. 1848-1856 ◽  
Author(s):  
C. Bledsoe ◽  
P. Klein ◽  
L. C. Bliss
Keyword(s):  
Plant Species ◽  
High Arctic ◽  
Cenococcum Geophilum ◽  
Soil Extracts ◽  
Vaccinium Uliginosum ◽  
Devon Island ◽  
Ericoid Mycorrhizae ◽  
Arctic Regions ◽  
Arctic Soils ◽  
Mycorrhizal Associations

Although mycorrhizal associations are commonly found on roots of most plant species, little is known about the presence or absence of mycorrhizae in arctic regions. In the Canadian High Arctic, roots of 55 herbaceous and woody plant species were examined for mycorrhizae during the summers of 1987 and 1988 on Devon Island, N.W.T. Ectomycorrhizal associations were found on roots of Salix arctica, Dryas integrifolia, and Potentilla hyparctica; ericoid mycorrhizae formed on Cassiope tetragona and Vaccinium uliginosum. Ectomycorrhizal roots were often covered with black hyphae resembling the fungus Cenococcum geophilum; sclerotia characteristic of this fungus were found in soil extracts. Plants expected to have endomycorrhizal associations were apparently nonmycorrhizal in the traditional sense, since no arbuscules, vesicles, or pelotons were found on any roots during two field seasons. Although extensive fungal hyphae were often present on and within roots, these hyphae could not be conclusively identified as endomycorrhizal. Some dark, septate hyphae were present; their function, although unknown, may be beneficial to the host. In a series of greenhouse bioassays using arctic soils, no endomycorrhizal associations developed on test plants. Spores of vesicular–arbuscular fungi were not found in soil extracts. Thus in this survey, only ectomycorrhizal associations were observed, suggesting that the cold, dry winter and cold, wet summer climates in this area of the High Arctic severely limit formation of endomycorrhizae. Key words: roots, fungi, ectomycorrhizae, endomycorrhizae, arctic.

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