Polar Research (E-Journal)
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Relation between planimetric and volumetric measurements of permafrost coast erosion: a case study from Herschel Island, western Canadian Arctic
No full textIce-rich permafrost coasts often undergo rapid erosion, which results in land loss and release of considerable amounts of sediment, organic carbon and nutrients, impacting the near-shore ecosystems. Because of the lack of volumetric erosion data, Arctic coastal erosion studies typically report on planimetric erosion. Our aim is to explore the relationship between planimetric and volumetric coastal erosion measurements and to update the coastal erosion rates on Herschel Island in the Canadian Arctic. We used high-resolution digital elevation models to compute sediment release and compare volumetric data to planimetric estimations of coastline movements digitized from satellite imagery. Our results show that volumetric erosion is locally less variable and likely corresponds better with environmental forcing than planimetric erosion. Average sediment release volumes are in the same range as sediment release volumes calculated from coastline movements combined with cliff height. However, the differences between these estimates are significant for small coastal sections. We attribute the differences between planimetric and volumetric coastal erosion measurements to mass wasting, which is abundant along the coasts of Herschel Island. The average recorded coastline retreat on Herschel Island was 0.68 m a−1 for the period 2000–2011. Erosion rates increased by more than 50% in comparison with the period 1970–2000, which is in accordance with a recently observed increase along the Alaskan Beaufort Sea. The estimated annual sediment release was 28.2 m3 m−1 with resulting fluxes of 590 kg C m−1 and 104 kg N m−1.Keywords: Coastal erosion; LiDAR; carbon fluxes; mass wasting; landslides; digital elevation model.(Published: 23 September 2016)To access the supplementary material for this article, please see Supplementary files under Article Tools online.Citation: Polar Research 2016, 35, 30313, http://dx.doi.org/10.3402/polar.v35.3031
Estimating sea-ice volume flux out of the Laptev Sea using multiple satellite observations
No full textSea-ice outflow from the Laptev Sea is of considerable importance in maintaining the Arctic Ocean sea-ice budget. In this study, a method exclusively using multiple satellite observations is used to calculate sea-ice volume flux across the eastern boundary (EB) and northern boundary (NB) of the Laptev Sea during the October–November and February–March or March–April periods (corresponding to the ICESat autumn and winter campaigns) between 2003 and 2008. Seasonally, the mean total ice volume flux (i.e., NB+EB) over the investigated autumn period (1.96 km3/day) is less than that over the winter period (2.57 km3/day). On the other hand, the large standard deviations of the total volume flux, 3.45 and 0.91 km3/day for the autumn and winter campaigns, indicate significant interannual fluctuations in the calculated quantities. A statistically significant (P>0.99) positive correlation, R=0.88 (or 0.81), is obtained between volume flux across the EB (or NB) and mean ice-drift speed over the boundary for the considered 11 ICESat campaigns. In addition, statistics show that a large fraction of the variability in volume flux across the NB over the 11 investigated campaigns, roughly 40%, is likely explained by ice thickness variability. On average, flux through the Laptev Sea amounts to approximately one-third of that across Fram Strait during the autumn and winter campaigns. These large contributions of sea ice from the Laptev Sea demonstrate its importance as an ice source, affecting the entire sea-ice mass balance in the Arctic Ocean.Keywords: Mass balance; remote sensing; climate change.(Published: 1 September 2016)To access the supplementary material for this article, please see the supplementary file in the column to the right (under Article Tools).Citation: Polar Research 2016, 35, 24875, http://dx.doi.org/10.3402/polar.v35.2487
Air temperature variations and gradients along the coast and fjords of western Spitsbergen
No full textDaily temperature measurements from six meteorological stations along the coast and fjords of western Spitsbergen have been digitized and quality controlled in a Norwegian, Russian and Polish collaboration. Complete daily data series have been reconstructed back to 1948 for all of the stations. One of the station’s monthly temperature series has previously been extended back to 1898 and is included in this study. The long-term series show large temperature variability on western Spitsbergen with colder periods in the 1910s and 1960s and warmer periods in the 1930s, 1950s and in the 21st century. The most recent years are the warmest ones in the instrumental records. There is a positive and statistically significant trend in the annual times series for all of the stations; however, the strongest warming is seen in winter and spring. For the period 1979–2015, the linear trends range from 1.0 to 1.3°C/decade for the annual series and from 2.0 to 2.3°C/decade in winter. Threshold statistics demonstrate a decrease in the number of cold days per year and an increase in the number of warm days. A decreasing inter-annual variability is observed. In winter, spring and autumn, the stations in the northernmost areas of west Spitsbergen and in the innermost parts of Isfjorden are the coldest ones. In summer, however, the southernmost station is the coldest one.Keywords: Svalbard; Arctic; trends; development; warming; temperature changes.(Published: 29 July 2016)To access the supplementary material for this article, please see the supplementary files in the column to the right (under Article Tools).Citation: Polar Research 2016, 35, 29878, http://dx.doi.org/10.3402/polar.v35.2987
First records of aphid-pathogenic Entomophthorales in the sub-Antarctic archipelagos of Crozet and Kerguelen
No full textSince the 20th century, the sub-Antarctic islands have suffered an increasing number of biological invasions. Despite the large number of publications on this topic, there is a lack of knowledge on parasitism rates of invasive species and on the role of parasites and pathogens to regulate their populations. Six aphid species have been introduced in the archipelagos of Crozet (Île de la Possession, 46° 25’ S–51° 51’ E) and Kerguelen (49° 21’ S–70° 13’ E). Five of these species were found infected by entomopathogenic fungi of the order Entomophthorales. All these fungal species are cosmopolitan. Conidiobolus obscurus and Entomophthora planchoniana were the most frequently observed on Île de la Possession and in Archipel des Kerguelen, respectively. This is the first report of pathogenic fungi of aphids on the sub-Antarctic islands. We discuss these results in the light of our current knowledge of these insect pathogens. Their introduction by aphids surviving on plants during transportation is the most likely hypothesis to explain their presence on these remote islands.Keywords: Natural enemies; introduced species; biological invasion; colonization; Zygomycetes; parasitism.(Published: 8 July 2016)Citation: Polar Research 2016, 35, 28765, http://dx.doi.org/10.3402/polar.v35.2876
Gastrointestinal helminths of Adélie penguins (Pygoscelis adeliae) from Antarctica
No full textKnowledge about parasitic organisms in Antarctica is scarce and fragmentary. The study reported here adds to the knowledge of gastrointestinal parasites of the Adélie penguin (Pygoscelis adeliae) (Sphenisciformes), from 25 de Mayo/King George Island (South Shetlands), Bahia Esperanza (Hope Bay) and Avian Island (Antarctica). Thirty-five freshly dead specimens (20 chicks and 15 adults) were collected from December 2007 to December 2014 and examined for internal macroparasites. Three adult parasite species were found: one Cestoda, Parorchites zederi, and two Nematoda, Stegophorus macronectes and Tetrameres sp. Immature Tetrabothrius sp. were found in hosts from Avian Island. Helminth communities are known to be related to host feeding behaviours. Low parasite richness observed in Adélie penguins could be related to the stenophagic and pelagic diet of this host species, which feeds almost exclusively on krill.Keywords: Parorchites zederi; Stegophorus macronectes; Tetrameres sp.; parasites; ecosystem health.(Published: 16 June 2016)Citation: Polar Research 2016, 35, 28516,http://dx.doi.org/10.3402/polar.v35.2851
Spatial distribution and synoptic conditions of snow accumulation in the Russian Arctic
No full textSnow accumulation and associated synoptic conditions in the Russian Arctic are analysed based on snow depth data from 1950 to 2013 from the All-Russian Research Institute of Hydrometeorological Information—World Data Centre data set. The mean duration of snow coverage in the Russian Arctic is approximately eight to nine months. While the period of snowmelt is usually very short (one or two months), snow accumulates during most of the cold season (October–May). Snow accumulation is associated with negative anomalies of sea level pressure and positive anomalies of air temperature, which means increased cyclonic activity over the analysed region. The cyclones differ in intensity and localization, depending on the area of snowfall. In the western part of the Russian Arctic the cyclones and air masses that bring snowfall may originate from the North Atlantic, while in the eastern part they originate from the Bering Sea, Okhotsk Sea or the North Pacific. The cyclones that bring snowfall may also form locally along the zonal border between two different air masses: the very cold, polar, continental air originating from the Siberian High and the Arctic air from the north, which is often warmer and always more humid than the continental air.Keywords: Polar climate; snow cover; air circulation patterns.(Published: 30 March 2016)To access the supplementary material for this article, please see the supplementary files in the column to the right (under Article Tools).Citation: Polar Research 2016, 35, 25916, http://dx.doi.org/10.3402/polar.v35.2591
Human fatigue and the crash of the airship Italia
No full textThe airship Italia, commanded by General Umberto Nobile, crashed during its return flight from the North Pole in 1928. The cause of the accident was never satisfactorily explained. We present evidence that the crash may have been fatigue-related. Nobile’s memoirs indicate that at the time of the crash he had been awake for at least 72 h. Sleep deprivation impairs multiple aspects of cognitive functioning necessary for exploration missions. Just prior to the crash, Nobile made three command errors, all of which are of types associated with inadequate sleep. First, he ordered a release of lift gas when he should have restarted engines (an example of incorrect data synthesis, with deterioration of divergent thinking); second, he inappropriately ordered the ship above the cloud layer (a deficiency in the assessment of relative risks); and third, he remained above the cloud layer for a prolonged period of time (examples of attention to secondary problems, and calculation problems). We argue that as a result of these three errors, which would not be expected from such an experienced commander, there was no longer enough static lift to maintain level flight when the ship went below the cloud layer. Applying Circadian Performance Simulation Software to the sleep–wake patterns described by Nobile in his memoirs, we found that the predicted performance for someone awake as long as he had been is extremely low. This supports the historical evidence that human fatigue contributed to the crash of the Italia.Keywords: Sleep; Nobile; polar exploration; aviation history; human error; mishap.(Published: 29 July 2016)To access the supplementary material for this article, please see the supplementary files in the column to the right (under Article Tools).Citation: Polar Research 2016, 35, 27105, http://dx.doi.org/10.3402/polar.v35.27105Citation: Polar Research 2016, 35, 27105, http://dx.doi.org/10.3402/polar.v35.27105Copyright: © 2016 G.A. Bendrick et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License, permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Published: 29 July 2016*Correspondence to: Gregg A. Bendrick, Armstrong Flight Research Center, National Aeronautics and Space Administration, PO Box 273, Mailstop 4822, Edwards Air Force Base, CA 93523, USA. E-mail: [email protected] access the supplementary material for this article, please see the supplementary files under Article Tools, online.
Depositional environment, ichnological features and oxygenation of Permian to earliest Triassic marine sediments in central Spitsbergen, Svalbard
No full textLate Early Permian–lowermost Triassic carbonate, siliceous (spiculites) and clastic marine sediments in the Marmierfjellet area (Isfjorden, central Spitsbergen) contain a relatively diverse and abundant trace fossil assemblage providing important information about the depositional processes. The Vøringen Member (Late Artinskian–Kungurian) of the Kapp Starostin Formation (Late Artinskian–? Changhsingian) contains trace fossils (Nereites, Phycosiphon, Zoophycos and Arenicolites—common in tempestites) typical of the proximal–archetypal Cruziana ichnofacies, which indicates lower shoreface. Nereites, Phycosiphon and Zoophycos, accompanied by other rare trace fossils, characterize the Svenskegga and Hovtinden members of the Kapp Starostin Formation. They are interpreted as the distal Cruziana ichnofacies, possibly transitional to the Zoophycos ichnofacies typical of the lower offshore zone. However, the sporadic occurrences of Arenicolites and Macaronichnus can point to episodic shallowing to upper offshore–lower shoreface. The lowest part of the Triassic Vikinghøgda Formation (Induan–Olenekian) contains a very low-diverse ichnoassemblage composed of a few simple and branched forms ascribed to the impoverished Cruziana ichnofacies (lower to upper offshore environment), which is attributed to the early recovery stage after the Permian–Triassic extinction. The trace fossils and loss of primary sedimentary structures caused by intense bioturbation throughout most of the section point to generally oxygenated pore waters on the sea floor. However, some horizons, especially laminated black shales, display reduced or no bioturbational activity. These horizons also show high V/(V+Ni) ratios, which indicate oxygen-depleted sediments with periods of anoxic conditions. A remarkable black shale unit deposited under anoxic and sulphidic conditions occurs at the Permian–Triassic transition.Keywords: Trace fossils; Permian–Triassic boundary; palynology; spiculites; trace elements; anoxicity.Published: 25 May 2016To access the supplementary material for this article, please see the supplementary files in the column to the right (under Article Tools).Citation: Polar Research 2016, 35, 24782, http://dx.doi.org/10.3402/polar.v35.2478
Sedimentary environments in the south-western Barents Sea during the last deglaciation and the Holocene: a case study outside the Ingøydjupet trough
No full textA lithological and foraminiferal study of newly acquired sediment cores outside the Ingøydjupet (Ingøy Deep) trough has been carried out to improve constraints on the last deglacial history in the south-western Barents Sea. Three lithofacies and three foraminiferal facies were identified. The lowermost lithological unit is a diamicton interpreted as glacial till. It contains a low-abundance, ecologically mixed foraminiferal assemblage, presumably resulting from glacial reworking. Above the diamicton, a layer of ice-rafted debris (IRD), likely associated with intensive iceberg production, marks the initial destabilization of the marine-based ice sheet. At this time, ca. 15.6–15.0 Ky B.P., opportunistic foraminiferal species Nonionellina labradorica and Stainforthia spp. reached peak abundance. During the south-western Barents Sea ice-margin retreat, presumably corresponding to the Bølling interstadial, a sequence of glaciomarine laminations was deposited conformably on the layer of IRD. Sedimentation rates were apparently high (estimated about 0.4 cm per year) and the foraminiferal fauna was dominated by Elphidium spp. and Cassidulina reniforme, species common for glacier-proximal environments. A hiatus at the top of the deglacial unit is likely linked to the high bottom-current activity associated with a strengthened inflow of Atlantic water masses into the Barents Sea. The uppermost lithological unit is represented by the Holocene marine sandy mud. It contains a high-abundance, high-diversity foraminiferal fauna with common cassidulinids, Cibicides spp., Epistominella pusilla and planktic species.Keywords: Deglaciation; Barents Sea ice sheet; sediment cores; lithofacies; biozonation.(Published: 5 May 2016)To access the supplementary material for this article, please see the supplementary file in the column to the right (under Article Tools).Citation: Polar Research 2016, 35, 23104, http://dx.doi.org/10.3402/polar.v35.2310
Leaf and floral heating in cold climates: do sub-Antarctic megaherbs resemble tropical alpine giants?
No full textHigh latitude and altitude floras are characterized by low-statured, small, wind-pollinated plants, which mainly reproduce by self-pollination or asexual reproduction. However, at odds with this are some sub-Antarctic islands that have plant species with giant growth forms and large, brightly coloured flowers which require insect visitation for pollination. The size, colour and shape of the inflorescences and leaves of these megaherbs suggest thermal benefits similar to giant tropical alpine plants of equatorial Africa, South America and Hawaii. We evaluated whether heating occurs in sub-Antarctic megaherbs, and to what extent it is related to environmental variables. We measured leaf and inflorescence temperature in six sub-Antarctic megaherb species on Campbell Island, latitude 52.3°S, New Zealand Biological Region. Using thermal imaging techniques, in combination with measurement of solar radiation, ambient air temperature, wind speed, wind chill and humidity, we assessed environmental influences on leaf and floral heating. We found that leaf and inflorescence temperatures of all megaherbs were higher than simultaneously measured ambient temperatures. Greatest heating was seen in Pleurophyllum speciosum, with observed leaves 9°C higher, and inflorescences nearly 11°C higher, than ambient temperature. Heating was highly correlated with brief, unpredictable periods of solar radiation, and occurred most rapidly in species with hairy, corrugated leaves and darkly pigmented, densely packed inflorescences. This is the first evidence that floral and leaf heating occurs in sub-Antarctic megaherbs, and suggests that leaf hairiness, flower colour and shape could provide thermal benefits like those seen in tropical alpine megaherbs.Keywords: Campbell Island; flower colour; thermal imaging; Pleurophyllum speciosum.(Published: 29 August 2016)To access the supplementary material for this article, please see the supplementary files in the column to the right (under Article Tools).Citation: Polar Research 2016, 35, 26030, http://dx.doi.org/10.3402/polar.v35.2603