High Arctic Environment Research Articles

Radionuclides in the Kongsfjorden area, Svalbard

The archipelago of Svalbard is located at the junction of Arctic Ocean, the North Atlantic and the Barents Sea. During a field campaign in May 2000, seawater, sea ice and seaweed, were collected in Kongsfjorden at the western coast of Spitsbergen. Possible sources for artificial radionuclides in the marine Svalbard environment are long-distance transported discharges from nuclear reprocessing plants, dumped radioactive waste, accidents with ships, submarines and power plants containing radioactive material, and global fallout from nuclear test explosions. Samples were taken to measure the radioisotopes technetium (Tc, sea water and seaweed), plutonium (sea water) and caesium ('Cs, sea water and melted sea ice). Certain processes are unique for the high-arctic environment such as formation of sea ice. The fast ice in Kongsfjorden provides an opportunity to investigate to what degree radionuclides accumulate in sea ice compared with the seawater below. Another important question relates to how radionuclides accumulate in the Arctic in different types of seaweed. First results from laboratory analyses of the samples taken in May 2000 show Tc concentrations in seawater similar to levels measured in the western Barents Sea in 1999-2000. Corresponding measurements along the Norwegian coast are one order of magnitude higher. Enhanced values measured at Hilles0y (Northern Norway), in the Barents Sea and off Svalbard and can be explained with increased discharges of Tc-contamina ted wastewater at the Sellafield reprocessing plant since 1994.

Seasonal carbon dioxide balance and respiration of a high-arctic fen ecosystem in NE-Greenland

Turbulent fluxes of CO2 were continuously measured by eddy correlation for three months in 1997 over a gramineous fen in a high-arctic environment at Zackenberg (74°28′12″N, 20°34′23″W) in NE-Greenland. The measurements started on 1 June, when there was still a 1–2 m cover of dry snow, and ended 26 August at a time that corresponds to late autumn at this high-arctic site. During the 20-day period with snow cover, fluxes of CO2 to the atmosphere were small, typically 0.005 mg CO2 m−2 s−1 (0.41 g CO2 m−2 d−1), wheres during the thawed period, the fluxes displayed a clear diurnal variation. During the snow-free period, before the onset of vegetation growth, fluxes of CO2 to the atmosphere were typically 0.1 mg CO2 m−2 s−1 in the afternoon, and daily sums reached values up to almost 9 g CO2 m−2 d−1. After 4 July, downward fluxes of CO2 increased, and on sunny days in the middle of the growing season, the net ecosystem exchange rates attained typical values of about −0.23 mg m−2 s−1 at midday and max values of daily sums of −12 g CO2 m−2 d−1. Throughout the measured period the fen ecosystem acted as a net-sink of 130 g CO2 m−2. Modelling the ecosystem respiration during the season corresponded well with eddy correlation and chamber measurements. On the basis of the eddy correlation data and the predicted respiration effluxes, an estimate of the annual CO2 balance the calender year 1997 was calculated to be a net-sink of 20 g CO2 m−2 yr−1.

Holocene glacimarine sedimentation, inner Scoresby Sund, East Greenland: the influence of fast-flowing ice-sheet outlet glaciers

Holocene glacimarine sedimentation associated with fast-flowing outlet glaciers draining the Greenland Ice Sheet is investigated using sedimentary and acoustic data from inner Scoresby Sund, East Greenland. Sedimentation in inner Scoresby Sund is dominated by three processes which are influenced by differences in proximity to fast-flowing outlet glaciers, extent of glacier-ice cover and fjord bathymetry: (1) sediment-gravity flow, principally in the form of turbidity currents and debris flows; (2) suspension sedimentation from turbid meltwater plumes; and (3) iceberg rafting. These processes result in texturally and sedimentologically heterogeneous lithofacies. Proportionally, fine-grained muds (laminated, stratified and massive facies) dominate cores recovered from inner Scoresby Sund, accounting for 80% of the total, whereas diamict facies account for only 15%. Abundant fine-grained muds demonstrate that meltwater flux and sedimentation is significant in this high Arctic glacimarine environment, in settings proximal to fast-flowing outlet glaciers. With increasing distance from these glacier termini, muds are replaced progressively by iceberg-rafted, coarse-grained sediment. The dominance of this iceberg-rafted sediment in outer Scoresby Sund reflects both its more distal location from fast-flowing glacier termini, and the high calving flux associated with these ice masses. Laminated muds deposited by turbidity currents and suspension settling from overflow plumes in inner Scoresby Sund are similar to lithofacies produced in temperate and subpolar glacimarine systems. This implies a similarity in sedimentation processes and resulting facies across a wide spectrum of climatically-, glaciologically- (fast-flowing and non fast-flowing ice-masses) and oceanographically-variable glacimarine settings. Recognition of laminated, fine-grained facies in the geological record therefore does not necessarily indicate a temperate palaeo-glacial setting. However, the predominance of iceberg-rafted diamict facies in ice-distal sedimentary records suggests the former presence of relatively cold environmental conditions in which iceberg-sedimentation played a dominant role.

Variation and control of growth-form in the moss Hylocomium splendens

The moss Hylocomium splendens has both sympodial and monopodial forms of growth. One aim of this study was to document the growth-form of shoots from different populations. A further aim was to discover the extent to which genetic or environmental factors determine whether monopodial or sympodial growth-form is predominant in a population. Switching between growth-forms within shoots occurs in most populations. Populations in forest habitats in temperate to mid-Arctic environments have predominantly sympodial shoots whereas shoots of populations from tundra habitats, in high-Arctic environments or at high altitudes, are predominantly monopodial. Transplant experiments showed that sympodial and monopodial shoots can respond plastically, by changing growth-form to some extent in different environments, and that high nutrient availability is an important environmental factor in promoting sympodial growth-form. However, even after 14 years, transplants did not show the same variation in growth-form as shoots in natural populations at the transplant sites. This suggests that populations are also genetically differentiated with respect to growth-form.

TRACKING LONG‐TERM CHANGES IN CLIMATE USING ALGAL INDICATORS IN LAKE SEDIMENTS

Interest in climate change research has taken on new relevance with the realization that human activities, such as the accelerated release of the so‐called greenhouse gases, may be altering the thermal properties of our atmosphere. Important social, economic, and scientific questions include the following. Is climate changing? If so, can these changes be related to human activities? Are episodes of extreme weather, such as droughts or hurricanes, increasing in frequency? Long‐term meteorological data, on broad spatial and temporal scales, are needed to answer these questions. Unfortunately, such data were never gathered; therefore, indirect proxy methods must be used to infer past climatic trends. A relatively untapped source of paleoclimate data is based on hindcasting past climatic trends using the environmental optima and tolerances of algae (especially diatoms) preserved in lake sediment profiles. Paleophycologists have used two approaches. Although still controversial, attempts have been made to directly infer climatic variables, such as temperature, from past algal assemblages. The main assumption with these types of analyses is that species composition is either directly related to temperature or that algal assemblages are related to some variable linearly related to temperature. The second more commonly used approach is to infer a limnological variable (e.g. water chemistry, lake ice cover, etc.) that is related to climate. Although paleolimnological approaches are broadly similar across climatic regions, the environmental gradients that paleophycologists track can be very different. For example, climatic inferences in polar regions have focused on past lake ice conditions, whereas in lakes near arctic treeline ecotones, paleophycologists have developed methods to infer past lakewater‐dissolved organic carbon, because this variable has been linked to the density of coniferous trees in a drainage basin. In closed‐basin lakes in arid and semiarid regions, past lakewater salinity, which can be robustly reconstructed from fossil algal assemblages, is closely tied to the balance of evaporation and precipitation (i.e. drought frequency). Some recent examples of paleophycolgical work include the documentation of striking environmental changes in high arctic environments in the 19th century believed to be related to climate warming. Meanwhile, diatom‐based reconstructions of salinity (e.g. the Great Plains of North America and Africa) have revealed prolonged periods of droughts over the last few millennia that have greatly exceeded those recorded during recent times. Marked climatic variability that is outside the range captured by the instrumental record has a strong bearing on sustainability of human societies. Only with a long‐term perspective can we understand natural climatic variability and the potential influences of human activities on climate and thereby increase our ability to understand future climate.

Glacier characteristics and sediment transfer system of Longyearbreen and Larsbreen, western Spitsbergen

Two small high-Arctic glaciers (Longyearbreen and Larsbreen) on Svalbard (78°N 15°E) were studied with respect to glaciological and hydrological characteristics. Fieldwork during the melting season of 1993 and 1994 was coupled with digital map analysis based on high-resolution digital elevation models (DEM) to reveal the dynamics and temperature regime of small glaciers in a high-Arctic environment, and its relationship to the material transport and sedimentation of these glaciers. The study showed Longyearbreen and Larsbreen to be low activity glaciers, cold-based with temperate patches, and thus having a low potential of basal erosion. The transport of ions and suspended solids in the glacial meltwater implies storage of material in and around the glacier which comes into contact with the meltwater. The study suggests that small Arctic glaciers couple the slope system with the fluvial system and therefore build a highly effective denudation system. Small polythermal glaciers are therefore important in understanding Pleistocene and Holocene landform development in cold regions.

Biological transport and mammal to mammal transfer of organochlorines in Arctic fauna

Ringed seal ( Phoca hispida) is assumed to be the most important and common prey of polar bears ( Ursus maritimus). However, during a scientific survey in the ice area of the northern Barents Sea east of Svalbard in June 1995, an unexpectedly high number of polar bears were observed feeding on harp seal ( Phoca groenlandica) carcasses. Samples of both harp and ringed seals were obtained and organochlorine (OC) occurrence and pattern in these two potential polar bear prey species were determined. Significantly higher OC concentrations were found in harp seals, as compared to the ringed seals. All animals in the northern harp seal group were lean specimens in late moult. The industrial chemicals, polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB), and the OC pesticides bis-2,2,(chlorophenyl)-1,1,1-trichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), and chlordanes (CHLORs) were analysed in blubber. The concentrations of ΣPCB (sum of concentrations of 16 PCB congeners) and ΣDDT (sum of concentrations of p,p′-DDT and p,p′-DDE) in the northern harp seal group ranged from 2093 to 20,382 and 1460 to 10,381 ng g −1 lipid weight, with mean concentrations of 11,133 and 6847 ng g −1 lipid weight, respectively. The mean concentrations of the CHLORs, oxychlordane and trans-nonachlor, were 1311 and 3743 ng g −1 lipid weight, respectively, while the mean concentrations of HCB and HCH isomers (α-, β- and γ-HCH) were all <500 ng g −1 lipid weight. No significant difference was found in the mean total blubber mass between the two seal species when collected in June. This indicates that polar bears preying on harp seals instead of ringed seals at this time of the year could accumulate significantly higher PCB concentrations. We suggest that polar bears feeding along the ice-edge east of Svalbard in May and June preferentially prey on harp seals instead of ringed seals, and that this may partly explain the variation in PCB concentrations among polar bears from the Norwegian Arctic. An hypothesis is that the harp seal may function as a transport vector of OCs into the high Arctic environment.

The Pre-Windermere Interstadial (Late Devensian) raised marine strata of eastern Scotland and their macrofauna: a review

Late Devensian raised marine deposits predating the Windermere Interstadial (c. 13–11 ka BP) are found between the Moray Firth and Berwick. The widely distributed, sparsely fossiliferous Errol Clay Formation of the firths of Forth and Tay was laid down in a high-arctic environment immediately following the retreat of the Late Devensian (Dimlington Stadial) ice. In the Tay Estuary, sedimentation took place under distal glaciomarine to marine conditions at a time when there was a fully marine connection between the Scottish east coast and the then high-arctic Norwegian Sea. On the south shore of the Moray Firth, the similar, but undated Spynie Clay Formation seems to have been laid down in a wholly glaciomarine environment. Part of the macrofauna attributed to the St. Fergus Silt Formation of the NE Scottish coast may have been either misidentified, or is not in situ. The preservation of the fauna and of delicate sedimentary structures indicate that the arctic clays as a whole were laid down rapidly. It is suggested that tidal currents were minimal, and that waves were dampened by sea ice for much of the year. Bones of the ringed seal, Phoca hispida, have been recorded from 12 sites in eastern Scotland. About 40 macrofaunal taxa are present in the Errol Clay Formation, a number similar to that recorded in the Danish Younger Yoldia Clay, which is of comparable age. The faunal nomenclature is updated, and three species ( Cylichna occulta, Retusa obtusa and Lyonsia arenosa) are added to the macrofaunal list for the Errol Clay Formation. Reports of in situ boreal molluscs and of one possibly North American species in the otherwise high-arctic assemblage are not supported by specimens in extant collections. Differential decay of the fauna below the zone of weathering in the Errol Clay Formation may have resulted from early diagenesis. Deposition of the Late Devensian, pre-Windermere Interstadial marine sediments as a whole was probably diachronous, beginning after 15–14 ka BP on the outer coast, but was confined to a short interval (c. 13.5–13 ka BP) at the type site in the Tay Estuary. In the Forth Estuary, the high-arctic marine fauna adjacent to the retreating ice-front may have survived the rapid climatic amelioration (c. 13 ka BP) at the beginning of the Windermere Interstadial (marked by the Main Perth Shoreline) for perhaps a few decades.

Vascular plant reproduction, establishment, and growth and the effects of cryptogamic crusts within a polar desert ecosystem, Devon Island, N.W.T., Canada

Most of the ice-free lands within the Canadian High Arctic are classified as polar desert (44%) or semidesert (49%). Much of this desert landscape supports no more than 6-10 vascular species that provide 1-3% cover and cryptogamic organisms that occupy 0-5% cover on the soil surface. The barrenness of these lands results from a short growing season and low summer temperatures that limit plant growth and the production of viable seeds. Limited areas have a 50-80% cover of cryptogamic crust and an 8-12% cover of vascular plants. These are areas in which surfaces remain moist for considerable periods in summer from snowflush waters. Where such cryptogamic soil crusts develop, they play a central role in soil development and nitrogen fixation. The two major components of this study were (i) an examination of fundamental reproductive, establishment, and growth characteristics of polar desert plants in the field and (ii) the relationship of these characteristics to environmental conditions in areas with and without cryptogamic crusts. Summer conditions during the study ranged from unusually warm (1991; 252 degree-days) to unusually cool (1992; 123 degree-days) with two average years (1994 and 1995; 172 and 166 degree-days, respectively). Differences in reproduction and establishment among these summers included (i) higher germination ability of seeds produced in the warm summer (1991) compared with more average summers (1994 and 1995) and (ii) significant seedling occurrence only in the average summers of 1994 and 1995. Seedling densities were much higher at crusted (206 seedlings/m2) than noncrusted sites (26 seedlings/m2). In both sites, root elongation of seedlings and older plants were significantly greater than shoot elongation, yet in established plants, shoot biomass was much greater than root biomass (root/shoot ratios from 0.1 to 0.3). Reproductive attributes varied among the species examined. Saxifraga caespitosa L. produced much smaller seeds then Draba corymbosa R. Br. ex DC. and Papaver radicatum Rottb., but the largest seeds of S. caespitosa (produced in the warm summer of 1991) had much higher germination rates than any seeds of the other species. Based on an analysis of population age structures, seedling survivorship was low for all species but was especially low for S. caespitosa, despite its higher germination rates. All species were slow to germinate, with isolated seeds under ideal controlled conditions requiring a minimum of 20-30 days at a 20°C day and 15°C night. Seed germination in excised soil blocks under comparable conditions averaged 36-48 days. We believe these polar desert plant species lack special attributes to uniquely exploit the environment of these very stressful locations. Rather, they are simply adept at surviving the rigors experienced there. The same species grow much larger, flower and fruit more abundantly, and produce more viable seeds in high arctic environments more favorable than polar deserts, such as lowland polar oases (e.g., Truelove Lowland, Devon Island, Canada). Within the harsh polar desert landscape of the High Arctic, the presence of a cryptogamic crust that retains surface moisture, prevents soil churning, and includes nitrogen-fixing organisms provides a more favorable habitat for plant reproduction, establishment, and growth.Key words: High Arctic, plant reproduction, plant establishment, plant growth, cryptogamic crust, polar desert, Devon Island.

Carbon dioxide exchange in a high-arctic fen estimated by eddy covariance measurements and modelling

Summary The high-arctic environment is an environment where the consequences of global warming may be significant. In this paper we report on findings on carbon dioxide and water vapour fluxes above a sedge-dominated fen at Zackenberg (74°28′N, 20°34′ W) in The National Park of North and East Greenland. Eddy covariance measurements were initiated at the start of the growing season and terminated shortly before its end lasting 45 days. The net CO2 flux during daytime reaches a high of 10 μmol m–2s–1, and around the summer solstice, net CO2 assimilation occurred at midnight, resulting in net carbon gain during the night. The measured carbon dioxide fluxes compare well to estimates based on the photosynthesis model byCollatz et al. (1991). The total growing-season net ecosystem CO2 exchange was estimated to be 96 g C m–2 based on the carbon dioxide model and micrometeorological data. Finally, the combined CO2 assimilation and soil respiration models are used for examining the dependence of the carbon dioxide budget on temperature. The ecosystem is found to function optimally given the present temperature conditions whereas either an increase or a decrease in temperature would reduce the ecosystem CO2 accumulation. An increase in temperature by 5 °C would turn the ecosystem into a carbon dioxide source.

Polyphyletic Origin of the Small-Bodied, High-Arctic Subspecies of Tundra Reindeer (Rangifer tarandus)

In order to investigate the origin of the three small-bodied, high-arctic subspecies of reindeer,Rangifer tarandus pearyi(the Canadian Archipelago),R. t. eogroenlandicus(East Greenland, extinct since 1900 AD), andR. t. platyrhynchus(Svalbard), samples were collected at nine localities from all six of the currently recognized subspecies of the tundra reindeer. A 203-bp-long fragment of the mitochondrial control region was sequenced from 113 reindeer (Rangifer tarandus). The now extinct subspeciesR. t. eogroenlandicuswas for the first time included in a molecular study; DNA was extracted from four museum specimens (skins and bones) and successfully sequenced. A polyphyletic origin for the three subspecies of small-bodied, high-arctic reindeer is suggested, withR. t. pearyiandR. t. eogroenlandicusbeing closely related and probably having evolved in high-arctic North America andR. t. platyrhynchusfrom Svalbard having evolved from Eurasian large-bodied reindeer. The small-bodied, high-arctic reindeer presumably represent ecotypes that have evolved convergently in similar high-arctic environments.

Modelling net radiation in a High Arctic environment using summer field camp data

A model is presented that uses easily obtained twice-daily field data (cloud-type, amount, temperature, wind speed at 2 m) to estimate net radiation for horizontal and slope sites in a High Arctic setting. Incoming shortwave radiation is estimated using a cloud-layer model, sensible and latent heat fluxes are determined using temperature and wind data, and the surface heat flux is obtained as the residual in the energy balance equation. Surface temperature, which is required for longwave radiation, is derived using the force–restore approach. The modelled results compare favourably with field measurements for a cool and wet (1989) and a warm and dry (1990) summer at Hot Weather Creek, Fosheim Peninsula, Ellesmere Island, Northwest Territories, Canada. Significant departures in the results tend to appear during the snowmelt period, suggesting that a better understanding of rapid albedo changes during the snowmelt season is required. A better agreement in 1990 may partly reflect lower errors in incoming shortwave radiation estimates and lower windspeeds, which dampened turbulent transfers. A variable dust coefficient used in the model and the use of cloud data twice daily may partly explain the underestimate of Q* in 1989 and its overestimate in 1990. Overall, the root-mean-square error for 1990 was 14–26 per cent when net radiation was averaged over a 5-day period. The model is useful to geomorphologists, hydrologists and ecologists interested in mapping the spatial pattern of net radiation for slopes, transects or drainage basins in northern environments. © 1997 The Royal Meteorological Society.

Chrysophyte stomatocyst assemblages associated with periphytic, high arctic pond environments

Chrysophycean stomatocysts associated with three different periphytic substrates (wet mosses, submerged mosses and rock scrapes) were investigated from ponds on Cape Herschel (78°37'N, 74°42'W), Ellesmere Island in the Canadian High Arctic. The goal of this study was to determine whether a distinct assemblage of periphytic chrysophyte cysts existed and, if so, whether assemblage composition varied with substrate and between ponds. One hundred and thirty‐seven different cyst morphotypes were observed with light microscopy from 68 periphytic samples taken from 35 ponds. Twenty‐six of these cysts were new morphotypes, of which 16 were identified and described using scanning electron microscopy. Significantly more cyst types with collars and hooked projections in the collar region (i.e. ‘hooked’), and fewer unomamented morphotypes were recorded in the periphytic habitats as compared to the surface sediments. Wet moss stomatocyst assemblages were particularly distinct, with a high number of heavily silicified and hooked morphotypes. The morphotype richness was far greater in periphytic environments, with 86, 100 and 95 morphotypes observed in the wet mosses, submerged mosses and rock scrapes, respectively, as compared to only 35 types in the surface sediments of the ponds. Canonical correspondence analysis indicated that measured water chemistry did not account for the variation in the species data (paxic 1 &lt; 0.01, 999 Monte Carlo permutations). This study suggests that distinct periphytic assemblages exist, and that cyst morphotype composition and richness varies with substrate.

The Growth Response of Graminoid Plants to Goose Grazing in a High Arctic Environment

1 The response of plants to herbivory usually varies with the grazing regime experienced. We investigated (i) if the timing and frequency of grazing affected plant growth, (ii) if faeces deposition by herbivores stimulated plant growth, and (iii) if grazing affected the total nonstructural carbohydrate (TNC) reserves in the below-ground vegetation of two arctic graminoids, Dupontiafisheri and Eriophorum scheuchzeri. 2 This study was conducted in polygon fens exposed to intense summer grazing by greater snow geese (Chen caerulescens atlantica) on Bylot Island (73?N) in the Canadian High Arctic. We manipulated the frequency (once or three times) and the timing (early, mid or late in the season) of grazing and faeces deposition in controlled grazing trials using captive goslings. 3 Although ungrazed plants were taller than grazed ones at the end of the season, data on cumulative tiller elongation (net above-ground height production) showed that plants grazed once or three times produced new foliage after each defoliation in both species. However, neither grazing (presence or absence) nor its frequency affected the net above-ground primary production (NAPP) or the number of tillers at the end of the summer. Nitrogen concentration was highest in plants grazed three times, intermediate in those grazed once, and lowest in ungrazed plants. 4 Timing of grazing and presence of goose faeces with or without grazing had no effect on plant growth. 5 Eriophorum plants grazed three times had less TNC in their below-ground tissues than ungrazed plants, and the trend was similar in Dupontia. 6 Dupontia and Eriophorum were able to compensate for leaves lost to grazing and to maintain production at a level similar to ungrazed plants, but at some cost (reduced below-ground reserves). The absence of an effect of faeces on plant growth may explain the absence of a positive effect of grazing on NAPP (i.e. overcompensation) in this ecosystem.

Comparative Winter Habitat Use and Associations among Herbivores in the High Arctic

We studied winter habitat use and interspecific associations among large- and medium-sized herbivores on southeastern Victoria Island, Arctic Canada, by documenting the deposition of feces in relation to vegetation. Associations between ptarmigan ( Lagopus spp.), arctic hares ( Lepus arcticus ), caribou ( Rangifer tarandus ), and muskoxen ( Ovibos moschatus ) were assessed using the Jaccard Index (JI) and chi² at two scales, i.e., with 1 m² and 1 ha as sampling units. JI values for species pairs were greater at the larger scale, but chi² revealed significant (positive) associations only at the smaller scale and only between arctic hares and caribou and between arctic hares and ptarmigan. Comparative use of habitats was described with respect to vegetation by canonical correspondence analysis (CCA). Ptarmigan and muskoxen were most strongly correlated with lowland vegetation and caribou with upland vegetation; arctic hares were intermediate. CCA also indicated rather wide separation in the multivariate space, further suggesting distinct patterns of habitat use. The results imply that these species were segregated in their use of resources in this High Arctic environment. Key words: arctic hare, caribou, habitat selection, interspecific relationships, multivariate, muskox, niche, ptarmigan, spatial scale

Space and Habitat Use by Greater Snow Goose Broods on Bylot Island, Northwest Territories

The brood-rearing season is a critical time for arctic-breeding geese because plant production is low and the growing season short. Thus, parental geese must efficiently exploit resources if young are to acquire adequate size and condition in preparation for fall migration. Current knowledge of habitat and space use by arctic-breeding geese is limited to some observations of unmarked birds. Thus, we studied habitat and space use of individual radio-marked greater snow geese (Chen caerulescens atlantica) in a high arctic environment. We radiotracked 20 goose families throughout the brood-rearing period in july and August 1989 and 1990, in a 70-km 2 area of wet tundra and upland habitats on Bylot Island, Northwest Territories

On the Habitat Specificity of the Testate Amoebae Assemblages from Devon Island (NWT, Canadian Arctic), with the Description of a New Species: Difflugia ovalisina

Summary A classification analysis of samples from different habitats demonstrates the importance of some ubiquistic and cosmopolitic taxa in high arctic environments. The number of habitat specific assemblages was found to be rather low: only 6 out of 18 recognized assemblages could be linked to a specific habitat. These assemblages are: for the soils, the Plagiopyxis callida assemblage; for the moss habitats, the Assulina muscorum — Corythion dubium , and the Euglypha rotunda assemblages; for the aquatic habitats, the Trinema lineare and the Paraquadrula irregularis — P. penardi assemblages. A new species, Difflugia ovalisina , is described.

Extreme adaptive life‐cycle in a high arctic aphid,Acyrthosiphon svalbardicum

Abstract.The year‐round biology of a high arctic aphid is described for the first time.The life‐cycle is shown to be genetically determined, and thus markedly different to temperate species where the observed polymorphism is governed primarily by external environmental cues.The fundatrix, which emerges from the overwintering egg, gives birth directly to sexual morphs, a phenomenon previously undescribed in the Aphidinae. This process is essentially prevented in temperate aphids by an endogenous mechanism, the interval timer.In addition to the sexual morphs, the fundatrix produces a small number of parthenogenetic individuals (viviparae) that give rise to a third generation. This last generation consists exclusively of oviparae and males that would increase the number of overwintering eggs provided there is sufficient thermal budget for them to mature and oviposit before conditions become adverse.The position of particular morphs in the birth sequences of the second and third generations maximize the chances of survival in harsh conditions, whilst enhancing the likelihood that individuals from the third generation will add to the number of overwintering eggs.Guaranteed egg production combined with an in‐built flexibility to produce an extra generation in particularly favourable seasons, confer adaptations to the high arctic environment, and ideally suit this aphid to exploit elevated temperatures in an era of climate change.

Russian Hunters on Svalbard and the Polar Winter

Ways of surviving in the High Arctic environment are among the most interesting problems addressed by archaeological research concerning hunting groups operating in these areas. The Svalbard archipelago affords a unique opportunity for comparative studies of arctic survival with respect to representatives from two different European cultural centers: the hunters from northern Russia and the western European whalers. The present paper concentrates on the Russian way of dealing with the polar winter. Both the documentary sources and the elements of material culture recovered during archaeological explorations reveal a relatively high level of adaptation to arctic conditions.Key words: polar winter, Svalbard, Pomorye, Russian hunting, Orthodox monasteries

Diatoms from the Shelton Mastodon Site

A fairly diverse and abundant diatom flora is associated with remains of Mammut americanum at the Shelton Mastodon Site in northern Oakland County, Michigan. The most abundant elements of this flora are species commonly recorded from late-glacial deposits in North America and Europe. The nearest modern analogues of this flora are assemblages deposited in small lakes in the high arctic and present day periglacial environments. Based on the diatoms present, the most probable depositional habitat was the margin of a moderately alkaline (pH>7.0) and moderately productive pond which existed under arctic conditions.