The ASTIS database contains the following 374 Polar Continental Shelf Program contributions, which are sorted here by contribution number.
Late Wisconsinan glaciation of the central sector of the Canadian High Arctic / Lamoureux, S.F. England, J.H.
(Quaternary research, v. 54, no. 2, Sept. 2000, p. 182-188, ill., maps)
(PCSP/PPCP contribution, no. 002-00)
ASTIS record 48773.
Geomorphic and chronological evidence from Cornwall Island in the Canadian High Arctic Archipelago provides direct evidence for the age and dynamics of the center and northern flank of the Innuitian Ice Sheet that covered the islands during the Late Wisconsonian glacial maximum. Dispersal of erratics and glacial landforms, indicate that ice flowed north across the island and converged with ice flowing northwest from Norwegian Bay. Cornwall Island was initially deglaciated at 9000 C14 yr B.P. in near synchrony with widely separated sites in adjacent parts of the archipelago. This regional chronology suggests rapid breakup of a marine-based Innuitian Ice Sheet that was destabilized by rapid eustatic sea-level rise and ice thinning during the early Holocene. This evidence provides strong support for a recently proposed ice divide spanning the central part of the Canadian High Arctic and indicates that most, if not all, of the region was glaciated during the Late Wisconsinan. (Au)
Deglaciation; Flow; Glacial epoch; Glacial geology; Glacial landforms; Glacial transport; Glaciation; Ice divides; Ice sheets; Recent epoch; Sea level; Sediments (Geology)
Cornwall Island, Nunavut; Devon Island, Nunavut; Ellesmere Island, Nunavut; Norwegian Bay, Nunavut
The last glaciation of east-central Ellesmere Island, Nunavut : ice dynamics, deglacial chronology, and sea level change / England, J. Smith, I.R. Evans, D.J.A.
(Canadian journal of earth sciences, v. 37, no. 10, Oct. 2000, p.1355-1371, ill., maps)
(PCSP/PPCP contribution, no. 007-00)
ASTIS record 48508.
During the last glacial maximum of east-central Ellesmere Island, trunk glaciers inundated the landscape, entering the Smith Sound Ice Stream. Accelerator mass spectrometry (AMS) dates on individual shell fragments in till indicate that the ice advanced after 19 ka BP. The geomorphic and sedimentary signatures left by the trunk glaciers indicate that the glaciers were polythermal. The configuration and chronology of this ice is relevant to the reconstruction of ice core records from northwestern Greenland, the history of iceberg rafting of clastic sediments to northern Baffin Bay, the reopening of the seaway between the Arctic Ocean and Baffin Bay, and the regional variability of arctic paleoenvironments. Deglaciation began with the separation of Ellesmere Island and Greenland ice at fiord mouths ~8-8.5 ka BP. Ice reached fiord heads between 6.5 and 4.4 ka BP. Trunk glacier retreat from the fiords of east-central Ellesmere Island occurred up to 3000 years later than in west coast fiords. This later retreat was favoured by (1) impoundment by the Smith Sound Ice Stream in Kane Basin until ~8.5 ka BP, which moderated the impact of high summer melt recorded in nearby ice cores between ~11.5 and 8.5 ka BP; (2) the shallow bathymetry and narrowness (<2 km) of the east coast fiords, which lowered calving rates following separation of Innuitian and Greenland ice; and (3) the likelihood of higher precipitation along east Ellesmere Island. Glaciers throughout the field area readvanced during the late Holocene. The greater advance of coastal glaciers is attributed to their proximity to the North Water polynya in Baffin Bay. (Au)
A, D, F
Aspect; Bathymetry; Cores; Deglaciation; Geological time; Geomorphology; Glacial deposits; Glacial landforms; Glaciation; Glaciers; Ice; Mass balance; Mass spectrometry; Moraines; Palaeogeography; Polynyas; Precipitation (Meteorology); Recent epoch; Sea level
G081, G0813, G0815, G09
Bache Peninsula, Nunavut; Baffin Bay-Davis Strait; Buchanan Bay region, Nunavut; Canadian Arctic Islands; Ellesmere Island, Nunavut; Flagler Bay region, Nunavut; Greenland; Herschel, Cape, region, Nunavut; Kane Basin, Greenland/Nunavut; Knud Peninsula, Nunavut; Nares Strait, Greenland/Nunavut; North Water Polynya, Baffin Bay; Nunavut; Princess Marie Bay region, Nunavut; Smith Sound, Greenland/Nunavut; Thorvald Peninsula, Nunavut
Mapping thermal and hydrological conditions beneath a polythermal glacier with radio-echo sounding / Copland, L. Sharp, M.
(Journal of glaciology, v. 47, no.157, 2001, p. 232-242, ill., maps)
(PCSP/PPCP contribution, no. 009-00)
ASTIS record 50642.
Spatial patterns in residual bed reflection power (BRPr), derived from ground-based radio-echo sounding, were mapped and interpreted in terms of the thermal and hydrological conditions at the base of a high-Arctic polythermal glacier (John Evans Glacier, Ellesmere Island, Canada). BRPr is the residual from a statistical relationship between measured bed reflection power and ice thickness that describes the rate of dielectric loss with depth in the glacier. We identified three types of thermal structure: (a) Positive BRPr and an internal reflecting horizon occur over the glacier terminus. The reflecting horizon is interpreted as the boundary between warm and cold ice, and suggests the presence of a warm basal layer. (b) Positive BRPr occurs without an internal reflector in the upper part of the ablation zone. This suggests that ice is at the pressure-melting point only at the bed. (c) Negative BRPr without an internal reflector occurs in all other regions, suggesting cold ice at the bed. Where BRPr is positive, its pattern is similar to the pattern of subglacial water flow predicted from the form of the subglacial hydraulic equipotential surface. This suggests that hydrological conditions at the glacier bed are a major control on BRPr, probably because the dielectric contrast between ice and water is higher than that between ice and other subglacial materials. (Au)
Ablation; Drainage; Electrical properties; Flow; Glacial melt waters; Glacier lakes; Glaciers; Mapping; Mathematical models; Measurement; Radar; Temperature; Thermal regimes; Thickness; Topography
John Evans Glacier, Nunavut
Late Early Permian plant fossils from the Canadian High Arctic : a rare paleoenvironmental/climatic window in northwest Pangea / LePage, B.A. Beauchamp, B. Pfefferkorn, H.W. Utting, J.
(Palaeogeography, palaeoclimatology, palaeoecology, v.191, no. 3-4, 20 Feb. 2003, p. 345-372, ill., maps)
(PCSP/PPCP contribution, no. 011-00)
ASTIS record 58086.
Recently discovered megafossil plant remains in late Early Permian (Kungurian) marine sediments on northern Axel Heiberg Island, Canadian Arctic Archipelago, provide a much needed datum point for paleobiogeographic considerations in this part of North America. The fossil plants represent at least ten families belonging to several major groups (sphenopsids, ferns, pteridosperms, ginkgos, cordaitaleans, and conifers). The conifers Rufloria and Walchia are the most commonly represented taxa, while other gymnosperms constitute much of the remaining collection. Lycopsids are absent and sphenopsids as well as ferns are present, but rare. The plant material probably originated from Crockerland and has a complex taphonomic history. There appears to be a strong phytogeographic connection with the Angaran floral realm. In addition, some floral elements occurring here are known mostly from the Early Mesozoic elsewhere. These findings support the idea that plant evolution was most intensive in extrabasinal settings; with migration into the depositional lowlands often occurring at times when climatic conditions became favorable for range expansion out of the uplands. The Axel Heiberg Island flora is another datum point for rare, but significant late Early Permian age floras on the North American continent. (Au)
B, A, H, E, J, I
Invertebrates; Limestone; Palaeobotany; Palaeoclimatology; Palaeoecology; Palaeogeography; Palaeontology; Palaeozoic era; Palynology; Permian period; Plant anatomy; Plant distribution; Plant taxonomy; Seeds; Sponges; Stratigraphy
G0813, G0815, G14, G10, G06, G02
Arctic waters; Axel Heiberg Island, Nunavut; Canadian Arctic Islands waters; North American Arctic; Russian Arctic
Movements and distribution of polar bears in the Beaufort Sea / Amstrup, S.C. Durner, G.M. Stirling, I. Lunn, N.J. Messier, F.
(Canadian journal of zoology, v. 78, no. 6, June 2000, p. 948-966, ill., maps)
(PCSP/PPCP contribution, no. 013-00)
ASTIS record 48676.
We fitted 173 satellite radio collars (platform transmitter terminals) to 121 adult female polar bears in the Beaufort Sea and relocated the bears 44 736 times between 1985 and 1995. We regularly resighted many instrumented bears so that we could ascertain whether changes in movements or distribution were related to reproductive status. Mean short-term movement rates were less than 2 km/h for all classes of bears. Maximum movement rates occurred in winter and early summer. In the southern Beaufort Sea (SBS), net geographic movements from the beginning to the end of each month were smaller for females with cubs of the year than for solitary females, and larger in November than in April, May, or July. In May, June, July, and August, radio-collared bears in the SBS moved north. They moved south in October. In the northern Beaufort Sea (NBS), bears moved north in June and south in March and September. Total annual movements ranged from 1406 to 6203 km. Mean total distances moved each month ranged from 79 to 420 km. Total monthly movements by SBS bears were largest in early winter and smallest in early spring. In the NBS, movements were largest in summer and smallest in winter. In the SBS, females with cubs moved less each month than other females. Annual activity areas ranged from 7264 to 596 800 km². Monthly activity areas ranged from 88 to 9760 km². Seasonal fidelity to activity areas of bears captured in all parts of the Beaufort Sea was strongest in summer and weakest in spring. (Au)
I, J, G
Ablation; Animal behaviour; Animal distribution; Animal ecology; Animal food; Animal live-capture; Animal physiology; Animal tagging; Formation; Movement; Pack ice; Polar bears; Radio tracking of animals; Sea ice; Seals (Animals)
Banks Island waters, N.W.T.; Canadian Beaufort Sea; Chukchi Sea; Prince Patrick Island waters, N.W.T.
Evolutionary origins of Antarctic microbiota : invasion, selection and endemism / Vincent, W.F.
(Antarctic science, v. 12, no. 3, Sept. 2000, p. 374-385, ill.)
(PCSP/PPCP contribution, no. 014-00)
ASTIS record 48582.
Increasing interest in the ecological roles, conservation and biotechnological potential of Antarctic microbiota has focused attention on their biodiversity and evolutionary origins. Antarctic microbial ecosystems provide useful models for general questions in evolutionary ecology given the relative isolation of the South Polar Region, the severe biological constraints imposed by the polar environment, and the absence of higher plants and animals in some Antarctic habitats. Sealed environments such as Lake Vostok and the overlying East Antarctic ice sheet provide unique, natural culture collections for studying microorganisms that have been isolated from the global gene pool over timescales of evolutionary significance. Most Antarctic environments, however, continue to receive microbial propagules from outside the region, as indicated by spore trap data, the microflora found in Antarctic snow and ice, the colonising taxa at geothermal sites, and the high frequency of apparently cosmopolitan species in most habitats. Differences in environmental stability and selection pressure among environments are likely to influence the degree of adaptive radiation and microbial endemism. The latter seems greater in the Southern Ocean by comparison with non-marine ecosystems of Antarctica, although there is some evidence of endemic species in highly specialised niches on the continent such as in the endolithic habitat beginning to provide new insights into the genetic affinities and biodiversity of Antarctic microbiota, and are leading to a more rigorous evaluation of microbial endemism. (Au)
H, G, J, I, D, E
Adaptation (Biology); Algae; Animal diseases; Animal distribution; Atmospheric circulation; Bacteria; Biology; Birds; Climate change; Cores; Evolution (Biology); Fishes; Fungi; Genetics; Marine mammals; Microorganisms; Ocean currents; Plant distribution; Protozoa; Refugia; Sea ice; Wildlife habitat; Winds
Antarctic regions; Bellingshausen Sea, Antarctic regions; Ross Sea, Antarctic regions; Vestfold Hills, Antarctic regions; Vostok, Lake, Antarctic regions; Weddell Sea, Antarctic regions
Life on snowball Earth / Vincent, W.F. Howard-Williams, C.
(Science, v.287, no.5462, 31 Mar. 2000, p.2421, 1 ill.)
(PCSP/PPCP contribution, no. 015-00)
ASTIS record 57772.
In his News Focus article "An appealing snowball Earth that's still hard to swallow" (10 Mar., p. 1734), Richard A. Kerr provides an update on the "snowball Earth" hypothesis, which proposes that around 600 and 2400 million years ago in the Proterozoic era there were several global ice ages interspersed with periods of global warming. One of the primary criticisms of the snowball Earth hypothesis is that thick sea ice over the entire world ocean would cut off the supply of sunlight to organisms in the seawater below and thereby eliminate photosynthesis. Others have similarly concluded that global-scale freezing would extinguish all surface life. Yet vast, biologically diverse cryo-ecosystems occur today throughout the Arctic and Antarctica. The closest analog to Proterozoic snowball Earth may be the thick (20 to 100 meters) landfast sea ice in the modern-day polar regions. On the McMurdo Ice Shelf in Antarctica and on the Ward Hunt Ice Shelf in the Canadian High Arctic, large areas (100 to 1000 square kilometers) of thick sea ice contain surface communities of highly pigmented microbial mats. These perennial mats are frozen into the ice and are inactive through most of the year. They thaw out for a brief (days to weeks) period of photosynthetic activity in late summer when meltwaters form on or in the ice despite air temperatures that are below 0°C. The modern-day ice shelf communities in both polar regions are dominated by oscillatorian cyanobacteria, a group that is widely distributed in the Proterozoic fossil record. These mat-forming organisms produce microhabitats for other biota, including viruses, bacteria, protists, and metazoa. The ice-mat environment offers protection against the effects of ultraviolet radiation and freeze-up and could have similarly provided refuge for the survival, growth, and evolution of less tolerant biota during the proposed Proterozoic glaciations. The alternation of global freeze-up and hothouse conditions during the Proterozoic might also help to explain the eurythermal characteristics of cyanobacteria that dominate in today's polar regions. The extreme cold tolerance of these organisms combined with their high-temperature optima for growth would seem to be an ideal strategy for surviving the "freeze-fry" travails of ancient Earth. (Au)
J, H, G, B, A
Bacteria; Cold adaptation; Cyanophyceae; Evolution (Biology); Glacial epoch; Ice shelves; Marine ecology; Microbial ecology; Microorganisms; Palaeobotany; Palaeoclimatology; Photosynthesis; Plant distribution; Plant growth; Proterozoic era; Protozoa; Puddles; Sea ice; Sea ice ecology; Thickness
Antarctic regions; McMurdo Ice Shelf, Antarctic regions; Ward Hunt Ice Shelf, Nunavut
Small scale plant distribution within a polar desert plateau, central Ellesmere Island, Canada / Lévesque, E.
(Écoscience, v. 8, no 3, 2001, p. 350-358, ill., 1 map)
(PCSP/PPCP contribution, no. 018-00)
ASTIS record 50486.
In order to quantify the availability of vacant favourable or "safe" microsites, the spatial distribution of plants on a sparsely vegetated dolomitic plateau was studied in central Ellesmere Island (Canada). Vegetation (vascular plants and bryophytes), boulders and polygon margins were mapped to the closest centimetre in a 10 m × 5 m plot and the microtopography of 8.5 m × 5 m of that plot was surveyed at a 10 cm × 10 cm scale. Vascular plant density was low (6.9 plants/m²). Individuals of the most frequent species found in the plot totalled 300 for Draba subcapitata Simm., 8 for Saxifraga oppositifolia L. and 27 for Papaver radicatum Rottb. Many plants grew in flat microsites in proximity to boulders and larger plants of the same species indicating successful, though infrequent, reproduction on the site. Still, the total uncolonized area including microsites around boulders and plants was much larger than the area occupied by plants (total plant cover = 0.16%). Clearly, vacant microsites were abundant on this polar desert plateau. However, the rare occurrence of established plants, in spite of the presence of viable seeds, implies that for an available microsite to become a favourable one, additional conditions must be met, such as moisture availability and higher temperatures. Adequate conditions may be met only infrequently, during favourable years. (Au)
H, E, J
Bioclimatology; Bryophytes; Growing season; Mapping; Meteorology; Microclimatology; Plant cover; Plant distribution; Plant ecology; Plant growth; Plant nutrition; Plant reproduction; Plant-soil relationships; Plants (Biology); Polar deserts; Precipitation (Meteorology); Topography; Winds
Ellesmere Island, Nunavut; Sverdrup Pass, Nunavut
Modern pollen assemblages in lake sediments from the Canadian Arctic / Gajewski, K.
(Arctic, antarctic, and alpine research, v. 34, no. 1, Feb. 2002, p. 26-32, ill., maps)
(PCSP/PPCP contribution, no. 021-00)
ASTIS record 51831.
Modern pollen assemblages from lakes in the Canadian high-arctic and middle-arctic vegetation zones are used to document geographic differences in pollen deposition. There are differences in the pollen percentages of the herbaceous taxa that can be used to discriminate the various regions of the Arctic. High-arctic pollen assemblages have higher Poaceae, while middle-arctic sediments have higher Cyperaceae percentages. Pollen spectra from Banks Island contain higher percentages of Saxifragaceae, Brassicaceae, and Tubuliflorae, while lake sediments from the central Arctic contain more Ranunculaceae and Caryophyllaceae pollen. Salix and Oxyria pollen percentages are relatively high in samples from Ellesmere Island. Pollen from the low-arctic and boreal zones can comprise a significant component of the assemblages in arctic sediments, and this is more important in the southern islands of the Canadian Arctic Archipelago. (Au)
B, H, E, F, J
Bottom sediments; Brassicaceae; Caryophyllaceae; Climatology; Geology; Grasses; Lakes; Mountain sorrel; Plant distribution; Plant nutrition; Plants (Biology); Pollen; Saxifraga; Sedges; Sedimentation; Spores; Taiga ecology; Tundra ecology; Willows
Axel Heiberg Island, Nunavut; Bathurst Island, Nunavut; Boothia Peninsula, Nunavut; Canadian Arctic Islands; Cornwallis Island, Nunavut; Devon Island, Nunavut; Ellesmere Island, Nunavut; Prince of Wales Island, Nunavut; Victoria Island, N.W.T./Nunavut
Farthest north lake and fjord populations of calanoid copepods, Limnocalanus macrurus and Drepanopus bengei in the Canadian High Arctic / Van Hove, P. Swadling, K.M. Gibson, J.A.E. Belzile, C. Vincent, W.F.
(Polar biology, v. 24, no. 5, Apr. 2001, p. 303-307, ill., maps)
(PCSP/PPCP contribution, no. 023-00)
ASTIS record 50272.
The zooplankton assemblages of Lake A and Disraeli Fjord, northern Ellesmere Island (83°N, 75°W), were surveyed in early summer 1999. In permanently ice-covered Lake A, two glacial relict calanoid copepod species (Drepanopus bungei and Limnocalanus macrurus) were found in the top 30 m. All developmental stages of the more abundant D. bungei were present, whereas only adults of L. macrurus were found. Analysis of gut contents showed that L. macrurus preyed upon the smaller species. A net tow sample of zooplankton from Disraeli Fjord was mainly composed of D. bungei and L. macrurus, along with two marine cyclopoid copepods (Oncaea borealis and Oithona similis). These two zooplankton communities occur within unusual environments that are strongly influenced by perennial ice and snow. They will be subject to major habitat disruption should the current warming trends continue in the north polar region. (Au)
I, E, H, D, F, J
Animal distribution; Animal food; Biological sampling; Biomass; Climate change; Copepoda; Fresh-water biology; Internal organs; Lakes; Melting; Necropsy; Ocean temperature; Phytoplankton; Salinity; Sea ice ecology; Temperature; Water masses; Wildlife habitat; Zooplankton
Disraeli Fiord region, Nunavut; Disraeli Fiord, Nunavut
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