Blar i NTNU Open på forfatter "Varpe, Øystein"

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    • Arctic complexity: A case study on diel vertical migration of zooplankton 

      Berge, Jørgen; Cottier, Finlo; Varpe, Øystein; Renaud, Paul; Falk-Petersen, Stig; Kwasniewski, Sawomir; Griffiths, Colin; Søreide, Janne; Johnsen, Geir; Aubert, Anais; Bjærke, Oda; Hovinen, Johanna Emilia Heidi; Jung-Madsen, Signe; Tveit, Martha; Markkula, Sanna (Journal article; Peer reviewed, 2014)

    • Body mass growth in nestlings of Svalbard snow buntings (Plectrophenax nivalis) in response to seasonal variation in arthropod biomass 

      Hilmarsen, Kjerstin Bakken (Master thesis, 2020)
      Hekkende fugler står overfor et utall avveininger i løpet av deres livssyklus for å maksimere overlevelse og reproduksjon som fører til høy levedyktighet. For trekkfugler inkluderer en av disse avveiningene når de skal ...

    • Causes and Consequences of Breeding Synchrony in the Snow Bunting (Plectrophenax nivalis ) 

      Skøien, Elida Arstad (Master thesis, 2015)
      Climate warming is happening rapidly in the Arctic and migratory birds are among the species expected to be affected by the predicted shifts in spring phenology. Using time-series data (1998 - 2014) from a population of ...

    • Centennial relationships between ocean temperature and Atlantic puffin production reveal shifting decennial trends 

      Hansen, Erpur S.; Sandvik, Hanno; Erikstad, Kjell E.; Yoccoz, Nigel; Anker-Nilssen, Tycho; Bader, Jürgen; Descamps, Sebastien; Hodges, Kevin; Mesquita, Michel d. S.; Reiertsen, Tone Kristin; Varpe, Øystein (Peer reviewed; Journal article, 2021)
      The current warming of the oceans has been shown to have detrimental effects for a number of species. An understanding of the underlying mechanisms may be hampered by the non-linearity and non-stationarity of the relationships ...

    • Climate trends, weather fluctuations and calving phenology in Svalbard reindeer (Rangifer tarandus platyrhynchus) 

      Danielsen, Preben (Master thesis, 2016)
      Reproduction is known to be one of the most energetically demanding processes in the life of an organism, and in seasonal environments, vertebrate offspring production is therefore timed to coincide with the annual peak ...

    • Cratering behaviour and faecal C:N ratio in relation to seasonal snow-pack characteristics in a High-Arctic ungulate 

      Beumer, Larissa Teresa; Varpe, Øystein; Hansen, Brage Bremset (Journal article; Peer reviewed, 2017)
      Snow and ice determine winter forage availability for Arctic herbivores. Winter precipitation is anticipated to increase, and icing following warm spells and rain-on-snow (ROS) are likely to become more frequent. While ...

    • Developing common protocols to measure tundra herbivory across spatial scales 

      Barrio, Isabel C.; Ehrich, Dorothee; Soininen, Eeva M; Ravolainen, Virve; Bueno, C. G.; Gilg, Olivier; Koltz, Amanda; Speed, James David Mervyn; Hik, David S.; Mörsdorf, M.; Alatalo, Juha M.; Angerbjørn, A.; Bêty, Joël; Bollache, L.; Boulanger-Lapointe, N.; Brown, G. S.; Eischeid, Isabell; Giroux, M. A.; Hajek, T.; Hansen, Brage Bremset; Hofhius, S. P.; Lamarre, J.-F.; Lang, J.; Latty, C.; Lecomte, N.; Macek, P.; McKinnon, L.; Myers-Smith, I. H.; Pedersen, Åshild Ønvik; Prevey, J. S.; Roth, J. D.; Saalfeld, S. T.; Schmidt, N. M.; Smith, P.; Sokolov, A.; Sokolova, N.; Stolz, C.; van Bemmelen, R.; Varpe, Øystein; Woodard, P. F.; Jonsdottir, I. S. (Peer reviewed; Journal article, 2021)
      Understanding and predicting large-scale ecological responses to global environmental change requires comparative studies across geographic scales with coordinated efforts and standardized methodologies. We designed, ...

    • Diel vertical migration of Arctic zooplankton during the polar night 

      Berge, Jørgen; Cottier, Finlo; Last, Kim S.; Varpe, Øystein; Leu, Eva; Søreide, Janne; Eiane, Ketil; Falk-Petersen, S.; Willis, Kate; Nygård, Henrik; Vogedes, Daniel; Griffiths, Collin; Johnsen, Geir; Lorentzen, Dag Arne; Brierley, A.S. (Journal article; Peer reviewed, 2009)
      High-latitude environments show extreme seasonal variation in physical and biological variables. The classic paradigm of Arctic marine ecosystems holds that most biological processes slow down or cease during the polar ...

    • Environmental correlates of variation in a holistic analysis of annual offspring production in the high Arctic songbird snow bunting (Plectrophenax nivalis) on Spitsbergen 

      Egil Lillehaug (Master thesis, 2019)
      Klima og vær er viktige abiotiske faktorer som påvirker organismer, spesielt i områder med store værforskjeller, som Arktis. Hvordan været påvirker reproduksjonssuksessen til en fugl som hekker der er spesielt interessant ...

    • Experimental icing affects growth, mortality, and flowering in a high Arctic dwarf shrub 

      Milner, Jos M; Varpe, Øystein; van der Wal, René; Hansen, Brage Bremset (Peer reviewed; Journal article, 2016)
      Effects of climate change are predicted to be greatest at high latitudes, with more pronounced warming in winter than summer. Extreme mid-winter warm spells and heavy rain-on-snow events are already increasing in frequency ...

    • In the dark: a review of ecosystem processes during the Arctic polar night 

      Berge, Jørgen; Renaud, Paul; Darnis, Gérald; Cottier, Finlo; Last, Kim; Gabrielsen, Tove M.; Johnsen, Geir; Seuthe, Lena; Weslawski, Jan Marcin; Leu, Eva; Moline, Mark A.; Nahrgang, Jasmine; Søreide, Janne; Varpe, Øystein; Lønne, Ole Jørgen; Daase, Malin; Falk-Petersen, Stig (Journal article, 2015)
      Several recent lines of evidence indicate that the polar night is key to understanding Arctic marine ecosystems. First, the polar night is not a period void of biological activity even though primary production is close ...

    • Is ambient light during the high Arctic polar night sufficient to act as a visual cue for zooplankton? 

      Cohen, Jonathan H.; Berge, Jørgen; Moline, Mark A.; Sørensen, Asgeir Johan; Last, Kim; Falk-Petersen, Stig; Renaud, Paul; Leu, Eva; Grenvald, Julie Cornelius; Cottier, Finlo; Cronin, Heather; Menze, Sebastian; Norgren, Petter; Varpe, Øystein; Daase, Malin; Darnis, Gérald; Johnsen, Geir (Journal article, 2015)
      The light regime is an ecologically important factor in pelagic habitats, influencing a range of biological processes. However, the availability and importance of light to these processes in high Arctic zooplankton communities ...

    • Later at higher latitudes: large-scale variability in seabird breeding timing and synchronicity 

      Burr, Zofia M.; Varpe, Øystein; Anker-Nilssen, Tycho; Erikstad, Kjell E; Descamps, Sébastien; Barrett, Robert T; Bech, Claus; Christensen-Dalsgaard, Signe; Lorentsen, Svein-Håkon; Moe, Børge; Reiertsen, Tone Kristin; Strøm, Hallvard (Journal article; Peer reviewed, 2016-05-28)
      In seasonal environments, organisms are expected to optimally schedule reproduction within an annual range of environmental conditions. Latitudinal gradients generate a range of seasonality to which we can expect adaptations ...

    • Marine Biomass Consumption by Wild Svalbard Reindeer: Fecal Stable Isotope Analysis as a Tool to Detect Climate Change Effects 

      Lorentzen, Jon Runar (Master thesis, 2015)
      Climate change in the Arctic is becoming evident with increased winter temperatures and changes in precipitation already perturbing Arctic ecosystems. Warm spells with rainfall in winter, also known as rain on snow (ROS) ...

    • A marine zooplankton community vertically structured by light across diel to interannual timescales 

      Hobbs, Laura; Banas, Neil S.; Cohen, Jonathan H.; Cottier, Finlo Robert; Berge, Jørgen; Varpe, Øystein (Journal article; Peer reviewed, 2021)
      The predation risk of many aquatic taxa is dominated by visually searching predators, commonly a function of ambient light. Several studies propose that changes in visual predation will become a major climate-change impact ...

    • Pelagic organisms avoid white, blue, and red artificial light from scientific instruments 

      Geoffroy, Maxime; Langbehn, Tom; Priou, Pierre; Varpe, Øystein; Johnsen, Geir; Le Bris, Arnault; Fisher, Jonathan A. D.; Daase, Malin; Mckee, David; Cohen, Jonathan H.; Berge, Jørgen (Journal article; Peer reviewed, 2021)
      In situ observations of pelagic fish and zooplankton with optical instruments usually rely on external light sources. However, artificial light may attract or repulse marine organisms, which results in biased measurements. ...

    • Reindeer turning maritime: Ice-locked tundra triggers changes in dietary niche utilization 

      Hansen, Brage Bremset; Lorentzen, Jon Runar; Welker, Jeffrey M.; Varpe, Øystein; Aanes, Ronny; Beumer, Larissa Teresa; Pedersen, Åshild Ø. (Journal article; Peer reviewed, 2019)
      The rapid warming of the Arctic may not only alter species’ abundances and distributions, but likely also the trophic interactions within and between ecosystems. On the high‐arctic tundra, extreme warm spells and associated ...

    • Stochastic rain events increase NDVI through moss water content: a High-Arctic field experiment 

      Valøen, Kristine (Master thesis, 2019)
      Målinger av ”Normalized Difference Vegetation Index” (NDVI) gjennom fjernmålinger blir brukt til å indikere produktiviteten til vegetasjonen i Høyarktis, og hvordan den påvirkes av klimaendringer. Tolkningen av observerte ...

    • Strengthening the evidence base for temperature-mediated phenological asynchrony and its impacts 

      Samplonius, Jelmer; Atkinson, Angus; Hassall, Christopher; Keogan, Katherine; Thackeray, Stephen J.; Assmann, Jakob J.; Burgess, Malcolm D.; Macphie, Kirsty H; Pearce-Higgins, James W.; Simmonds, Emily Grace; Johansson, Jacob; Varpe, Øystein; Weir, James C; Childs, Dylan Z.; Cole, Ella F.; Daunt, Francis; Hart, Tom; Lewis, Owen T.; Pettorelli, Nathalie; Sheldon, Ben C.; Phillimore, Albert B. (Journal article; Peer reviewed, 2020)
      Climate warming has caused the seasonal timing of many components of ecological food chains to advance. In the context of trophic interactions, the match–mismatch hypothesis postulates that differential shifts can lead to ...

    • Towards rainy Arctic winters: effects of experimental icing on tundra plants and their soil conditions 

      Le Moullec, Mathilde; Isaksen, Ketil; Petit Bon, Matteo; Jónsdóttir, Ingibjörg Svala; Varpe, Øystein; Hendel, Anna-Lena; Beumer, Larissa Teresa; Hansen, Brage Bremset (MET report;, Research report, 2019)
      Global warming comes with more frequent extreme climate events. In the Arctic, extreme warm spells with heavy rain-on-snow events in winter can cause dramatic changes to the snow-pack and encapsulate the vegetation in thick ...