Viser treff 1485-1504 av 1513

    • What we do in the dark: Prevalence of omnivorous feeding activity in Arctic zooplankton during polar night 

      Kunisch, Erin; Graeve, Martin; Gradinger, Rolf Rudolf; Flores, Hauke; Varpe, Øystein; Bluhm, Bodil (Journal article; Tidsskriftartikkel, 2023-07-04)
      During the productive polar day, zooplankton and sea-ice amphipods fulfill a critical role in energy transfer from primary producers to higher trophic-level species in Arctic marine ecosystems. Recent polar night studies on zooplankton and sea-ice amphipods suggest higher levels of biological activity than previously assumed. However, it is unknown if these invertebrates maintain polar night activity ...
    • When a year is not enough: Further study of the seasonality of planktonic protist communities structure in an ice-free high arctic fjord (adventfjorden, west spitsbergen) 

      Dabrowska, Anna Maria; Wiktor, Józef Maria; Wiktor, Józef Mikolaj; Kristiansen, Svein; Vader, Anna; Gabrielsen, Tove (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-20)
      As a contribution to understanding the ecological framework of protistan seasonal succession patterns, we present the weekly-to-monthly (January–October) light microscopy-based study of nano- and microplanktonic protist communities of Adventfjorden waters in 2013. In general, protist dynamics corresponded to the classic paradigm for the Arctic ice-free waters with extremely low abundance and diversity ...
    • When spring ephemerals fail to meet pollinators: Mechanism of phenological mismatch and its impact on plant reproduction 

      Kudo, Gaku; Cooper, Elisabeth J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-12)
      The flowering phenology of early-blooming plants is largely determined by snowmelt timing in high-latitude and high-altitude ecosystems. When the synchrony of flowering and pollinator emergence is disturbed by climate change, seed production may be restricted due to insufficient pollination success. We revealed the mechanism of phenological mismatch between a spring ephemeral (<i>Corydalis ambigua</i>) ...
    • When the brain goes diving: transcriptome analysis reveals a reduced aerobic energy metabolism and increased stress proteins in the seal brain 

      Fabrizius, Andrej; Hoff, Mariana Leivas Müller; Engler, Gerhard; Folkow, Lars; Burmester, Thorsten (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-08-09)
      <b>Background: </b>During long dives, the brain of whales and seals experiences a reduced supply of oxygen (hypoxia). The brain neurons of the hooded seal (Cystophora cristata) are more tolerant towards low-oxygen conditions than those of mice, and also better survive other hypoxia-related stress conditions like a reduction in glucose supply and high concentrations of lactate. Little is known ...
    • Where are they now? – A case study of the impact of international travel support for early career Arctic researchers 

      Majaneva, Sanna Kristiina; Hamon, Gwenaelle; Fugmann, Gerlis Ursula; Lisowska, Maja; Baeseman, Jenny Lynn (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09)
      Supporting and training the next generation of researchers is crucial to continuous knowledge and leadership in Arctic research. An increasing number of Arctic organizations have developed initiatives to provide travel support for Early Career Researchers (ECRs) to participate in workshops, conferences and meetings and to network with internationally renowned scientific leaders. However, there has ...
    • Where do the treeless tundra areas of northern highlands fit in the global biome system: toward an ecologically natural subdivision of the tundra biome 

      Virtanen, Risto; Oksanen, Lauri Kalervo; Oksanen, Tarja Maarit; Cohen, Juval; Forbes, Bruce C.; Johansen, Bernt; Käyhkö, Jukka; Olofsson, Johan; Pulliainen, Jouni; Tømmervik, Hans (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-15)
      According to some treatises, arctic and alpine sub-biomes are ecologically similar, whereas others find them highly dissimilar. Most peculiarly, large areas of northern tundra highlands fall outside of the two recent subdivisions of the tundra biome. We seek an ecologically natural resolution to this long-standing and far-reaching problem. We studied broad-scale patterns in climate and ...
    • Whirly proteins as communicators between plant organelles and the nucleus? 

      Krause, Kirsten; Herrmann, Ullrich; Fuss, Janina; Miao, Ying; Krupinska, Karin (Journal article; Tidsskriftartikkel; Peer reviewed, 2009)
      Whirly proteins belong to a small family of proteins with a characteristic secondary structure and a conserved DNA binding domain that is found mainly in angiosperms. At least one member of the Whirly protein family, Whirly1, is dually targeted to the nucleus and to the chloroplasts and it was shown that apart from its initially described function as a transcriptional regulator of nuclear disease ...
    • Why are Svalbard Arctic foxes Brucella spp. seronegative? 

      Nymo, Ingebjørg Helena; Fuglei, Eva; Mørk, Torill; Breines, Eva Marie; Holmgren, Karin Elisabeth; Davidson, Rebecca K.; Tryland, Morten (Journal article; Tidsskriftartikkel, 2022-07-06)
      Arctic foxes (Vulpes lagopus) are susceptible to smooth Brucella (s-Brucella) infection and may be exposed to such bacteria through the consumption of infected marine mammals, as implied by the finding of s-Brucella antibodies in polar bears (Ursus maritimus). Arctic foxes in Svalbard have not previously been investigated for s-Brucella antibodies, but such antibodies have been detected in Arctic ...
    • Why do the boreal forest ecosystems of Northwestern Europe differ from those of Western North America? 

      Boonstra, Rudy; Andreassen, Harry Peter; Boutin, Stan; Husek, Jan; Ims, Rolf Anker; Krebs, Charles J.; Skarpe, Christina; Wabakken, Petter (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-07-20)
      The boreal forest is one of the largest terrestrial biomes on Earth. Conifers normally dominate the tree layer across the biome, but other aspects of ecosystem structure and dynamics vary geographically. The cause of the conspicuous differences in the understory vegetation and the herbivore–predator cycles between northwestern Europe and western North America presents an enigma. Ericaceous dwarf ...
    • Why don't all species overexploit? 

      Vuorinen, Katariina Elsa Maria; Oksanen, Tarja Maarit; Oksanen, Lauri; Vuorisalo, Timo; Speed, James David Mervyn (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-14)
      Overexploitation of natural resources is often viewed as a problem characteristic of only the human species. However, any species could evolve a capacity to overexploit its essential resources through natural selection and competition, even to the point of resource collapse. Here, we describe the processes that potentially lead to overexploitation and synthesize what is known about overexploitation ...
    • Why Rudolph's nose is red: observational study 

      Ince, Can; van Kuijen, Anne-Marie; Milstein, Dan M J; Yürük, Koray; Folkow, Lars; Fokkens, Wytske J; Blix, Arnoldus S (Journal article; Tidsskriftartikkel, 2012-12-17)
      Objective To characterise the functional morphology of the nasal microcirculation in humans in comparison with reindeer as a means of testing the hypothesis that the luminous red nose of Rudolph, one of the most well known reindeer pulling Santa Claus’s sleigh, is due to the presence of a highly dense and rich nasal microcirculation.<p> <p>Design Observational study.<p> <p>Setting Tromsø, ...
    • A Widely Distributed Thraustochytrid Parasite of Diatoms Isolated from the Arctic Represents a gen. and sp. nov. 

      Hassett, Brandon (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-06)
      A unicellular, heterotrophic, eukaryotic parasite was isolated from nearshore Arctic marine sediment in association with the diatom <i>Pleurosigma</i> sp. The parasite possessed ectoplasmic threads that could penetrate diatom frustules. Healthy and reproducing <i>Pleurosigma</i> cultures would begin to collapse within a week following the introduction of this parasite. The parasite (2–10 μm diameter) ...
    • Widely rhythmic transcriptome in Calanus finmarchicus during the high Arctic summer solstice period 

      Payton, Laura; Hüppe, Lukas; Noirot, Celine; Hoede, Claire; Last, Kim; Wilcockson, David; Ershova, Elizaveta; Valière, Sophie; Meyer, Bettina (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-10)
      Solar light/dark cycles and seasonal photoperiods underpin daily and annual rhythms of life on Earth. Yet, the Arctic is characterized by several months of permanent illumination (“midnight sun”). To determine the persistence of 24h rhythms during the midnight sun, we investigated transcriptomic dynamics in the copepod <i>Calanus finmarchicus</i> during the summer solstice period in the Arctic, with ...
    • Widespread soil bacterium that oxidizes atmospheric methane 

      Tveit, Alexander Tøsdal; Hestnes, Anne Grethe; Robinson, Serina Lee; Schintlmeister, Arno; Dedysh, Svetlana N; Jehmlich, Nico; Bergen, Martin von; Herbold, Craig; Wagner, Michael; Richter, Andreas; Svenning, Mette Marianne (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-08)
      Increasing atmospheric methane concentrations contribute significantly to global warming. The only known biological sink for atmospheric methane is oxidation by methane oxidizing bacteria (MOB). Due to the lack of pure cultures, the physiology and metabolic potential of MOB that oxidize atmospheric methane remains a mystery. Here, we report on isolation and characterization of a MOB that can grow ...
    • Will borealization of Arctic tundra herbivore communities be driven by climate warming or vegetation change? 

      Speed, James David Mervyn; Chimal-Ballesteros, J. Adrian; Martin, Michael D.; Barrio, Isabel C.; Vuorinen, Katariina Elsa Maria; Soininen, Eeva M (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-30)
      Poleward shifts in species distributions are expected and frequently observed with a warming climate. In Arctic ecosystems, the strong warming trends are associated with increasing greenness and shrubification. Vertebrate herbivores have the potential to limit greening and shrub advance and expansion on the tundra, posing the question of whether changes in herbivore communities could partly mediate ...
    • Will borealization of Arctic tundra herbivore communities be driven by climate warming or vegetation change? 

      Speed, James David Mervyn; Chimal Ballesteros, Jesus Adrian; Martin, Michael David; Barrio, Isabel C.; Vuorinen, Katariina Elsa Maria; Soininen, Eeva Marjatta (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-30)
      Poleward shifts in species distributions are expected and frequently observed with a warming climate. In Arctic ecosystems, the strong warming trends are associated with increasing greenness and shrubification. Vertebrate herbivores have the potential to limit greening and shrub advance and expansion on the tundra, posing the question of whether changes in herbivore communities could partly mediate ...
    • Winter quarters of wetland ground beetles (Coleoptera, Carabidae) in South Scandinavia 

      Andersen, Johan (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      Sites at various distances from eutrophic and mesotrophic lakes and fens on the island Öland in southern Sweden were systematically surveyed in summer (May–August) and autumn (late September–October) to elucidate the hibernation sites of wetland carabid beetles. Thirty-five of 47 wetland species were found in their winter quarters. In areas ≤50 m from the lakes and fens, the observed as well as the ...
    • Winters are changing: snow effects on Arctic and alpine tundra ecosystems 

      Rixen, Christian; Høye, Toke Thomas; Macek, Petr; Aerts, Rien; Alatalo, Juha; Andeson, Jill; Arnold, Pieter; Barrio, Isabel C.; Bjerke, Jarle W.; Björkman, Mats P.; Blok, Daan; Blume-werry, Gesche; Boike, Julia; Bokhorst, Stef; Carbognani, Michele; Christiansen, Casper Tai; Convey, Peter; Cooper, Elisabeth J.; Cornelissen, J. Hans C.; Coulson, Stephen; Dorrepaal, Ellen; Elberling, Bo; Elmendorf, Sarah; Elphinstone, Cassandra; Forte, T'ai Gladys Whittingham; Frei, Esther R.; Geange, Sonya Rita; Gehrmann, Friederike; Gibson, Casey; Grogan, Paul; Rechsteiner, Aud Helen Halbritter; Harte, John; Henry, Greg H.R.; Inouye, David W.; Irwin, Rebecca; Jespersen, Gus; Jónsdóttir, Ingibjörg Svala; Jung, Ji Young; Klinges, David H.; Kudo, Gaku; Lämsä, Juho; Lee, Hanna; Lembrechts, Jonas; Lett, Signe; Lynn, Joshua Scott; Mann, Hjalte Mads; Mastepanov, Mikhail; Morse, Jennifer; Myers-Smith, Isla; Olofsson, Johan; Semenchuk, Philipp; Vandvik, Vigdis (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-18)
      Snow is an important driver of ecosystem processes in cold biomes. Snow accumulation determines ground temperature, light conditions and moisture availability during winter. It also affects the growing season’s start and end, and plant access to moisture and nutrients. Here, we review the current knowledge of the snow cover’s role for vegetation, plant-animal interactions, permafrost conditions, ...
    • Within and between breeding-season changes in contaminant occurrence and body condition in the Antarctic breeding south polar skua 

      Midthaug, Hilde Karin; Hitchcock, Daniel James; Bustnes, Jan Ove; Polder, Anuschka; Descamps, Sebastien; Tarroux, Arnaud; Soininen, Eeva M; Borgå, Katrine (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-24)
      The Antarctic ecosystem represents a remote region far from point sources of pollution. Still, Antarctic marine predators, such as seabirds, are exposed to organohalogen contaminants (OHCs) which may induce adverse health effects. With increasing restrictions and regulations on OHCs, the levels and exposure are expected to decrease over time. We studied south polar skua (<i>Catharacta maccormicki</i>), ...
    • The World's Northernmost Harbour Seal Population - How Many Are There? 

      Merkel, Benjamin; Lydersen, Christian; Yoccoz, Nigel; Kovacs, Kit (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      This study presents the first abundance estimate for the world’s northernmost harbour seal (Phoca vitulina) population, which resides in Svalbard, Norway, based on three digital stereoscopic photographic surveys conducted in 2009 and 2010. The counts from these high resolution 3D images were combined with a novel method for estimating correction factors for animals that were in the water at the ...