Now showing items 1448-1467 of 1515

    • Upward nitrate flux and downward particulate organic carbon flux under contrasting situations of stratification and turbulent mixing in an Arctic shelf sea 

      Wiedmann, Ingrid; Tremblay, Jean-Éric; Sundfjord, Arild; Reigstad, Marit (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-08-02)
      Increased sea ice melt alters vertical surface-mixing processes in Arctic seas. More melt water strengthens the stratification, but an absent ice cover also exposes the uppermost part of the water column to wind-induced mixing processes. We conducted a field study in the Barents Sea, an Arctic shelf sea, to examine the effects of stratification and vertical mixing processes on 1) the upward nitrate ...
    • The urgency of Arctic change 

      Overland, James; Dunlea, Edward; Box, Jason E.; Corell, Robert; Forsius, Martin; Kattsov, Vladimir; Olsen, Morten Skovgård; Pawlak, Janet; Reiersen, Lars Otto; Wang, Muyin (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-27)
      This article provides a synthesis of the latest observational trends and projections for the future of the Arctic. First, the Arctic is already changing rapidly as a result of climate change. Contemporary warm Arctic temperatures and large sea ice deficits (75% volume loss) demonstrate climate states outside of previous experience. Modeled changes of the Arctic cryosphere demonstrate that even ...
    • Use of an Autonomous Surface Vehicle reveals small-scale diel vertical migrations of zooplankton and susceptibility to light pollution under low solar irradiance 

      Ludvigsen, Martin; Berge, Jørgen; Geoffroy, Maxime; Cohen, Jonathan H.; De La Torre, Pedro R.; Nornes, Stein Melvær; Singh, Hanumant; Sørensen, Asgeir Johan; Daase, Malin; Johnsen, Geir (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-10)
      Light is a major cue for nearly all life on Earth. However, most of our knowledge concerning the importance of light is based on organisms’ response to light during daytime, including the dusk and dawn phase. When it is dark, light is most often considered as pollution, with increasing appreciation of its negative ecological effects. Using an Autonomous Surface Vehicle fitted with a hyperspectral ...
    • The use of the nest for parental roosting and thermal consequences of the nest for nestlings and parents 

      Nilsson, Jan-Åke; Nord, Andreas (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-07)
      Abstract<br> At temperate latitudes, altricial birds and their nestlings need to handle night temperatures well below thermoneutrality during the breeding season. Thus, energy costs of thermoregulation might constrain nestling growth, and low nocturnal temperatures might require resources that parents could otherwise have invested into nestlings during the day. To manipulate parental work rate, we ...
    • Use of unmanned aircraft systems (UAS) in a multi-scale vegetation index study of arctic plant communities in Adventdalen on Svalbard 

      Tømmervik, Hans; Karlsen, Stein-Rune; Nilsen, Lennart; Johansen, Bernt; Storvold, Rune; Zmarz, Anna; Beck, Pieter S.; Høgda, Kjell Arild; Goetz, Scott; Park, Taejin; Zagajewski, Bogdan; Myneni, Ranga B.; Bjerke, Jarle W. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
      Use of Unmanned Aircraft Systems (UAS) gives the opportunity to carry out research with a re-duced environmental footprint. Unmanned aircraft, including both fixed wing and multi rotor types (helicopters) allow us to collect very high resolution image data for vegetation mapping without the need for any personnel walking into the site and thereby potentially disturbing the sensitive Arctic ecosystems. ...
    • Using camera traps to monitor cyclic vole populations 

      Kleiven, Eivind Flittie; Antunes Lopes Da Silva Nicolau, Pedro Guilherme; Sørbye, Sigrunn Holbek; Aars, Jon; Yoccoz, Nigel; Ims, Rolf Anker (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-02)
      Camera traps have become popular labor-efficient and non-invasive tools to study animal populations. The use of camera trap methods has largely focused on large animals and/or animals with identifiable features, with less attention being paid to small mammals, including rodents. Here we investigate the suitability of camera-trap-based abundance indices to monitor population dynamics in two species ...
    • Using crowdsourced spatial data from Flickr vs. PPGIS for understanding nature's contribution to people in Southern Norway 

      Munoz, Lorena; Hausner, Vera Helene; Runge, Claire Alice; Brown, Greg; Daigle, Remi (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-20)
      <ol> <li>Crowdsourced data can provide spatially explicit data on the contribution of nature to people. Spatial information is essential for effectively managing the diverse relationships that people have with nature, but the potential and limits of using crowdsourcing data to generate maps for conservation purposes need further research. </li><p> <p><li>Passive crowdsourcing tools include social ...
    • Using Ordinary Digital Cameras in Place of Near-Infrared Sensors to Derive Vegetation Indices for Phenology Studies of High Arctic Vegetation 

      Anderson, Helen; Nilsen, Lennart; Tømmervik, Hans; Karlsen, Stein Rune; Nagai, Shin; Cooper, Elisabeth J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
      To remotely monitor vegetation at temporal and spatial resolutions unobtainable with satellite-based systems, near remote sensing systems must be employed. To this extent we used Normalized Difference Vegetation Index NDVI sensors and normal digital cameras to monitor the greenness of six different but common and widespread High Arctic plant species/groups (graminoid/Salix polaris; Cassiope tetragona; ...
    • Using subnivean camera traps to study arctic small mammal community dynamics during winter 

      Mölle, Jonas; Kleiven, Eivind Flittie; Ims, Rolf Anker; Soininen, Eeva M (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-12)
      Small rodents are a key indicator to understand the effect of rapidly changing winter climate on Arctic tundra ecosystems. However, monitoring rodent populations through the long Arctic winter by means of conventional traps has, until now, been hampered by snow cover and harsh ambient conditions. Here, we conduct the first extensive assessment of the utility of a newly developed camera trap to ...
    • Validation of pop-up satellite archival tags (PSATs) on Atlantic cod (Gadus morhua) in a Greenland fjord 

      Nielsen, Julius; Estévez-Barcia, Daniel; Post, Søren; Christensen, Helle Torp; Retzel, Anja; Meire, Lorenz; Rigét, Frank; Strøm, John Frederik; Rikardsen, Audun H.; Hedeholm, Rasmus (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-28)
      Traditional tagging techniques are simple and cost-effective, but inferences require recaptures and data on movement/migration are limited to a start and end position at unpredictable intervals. Pop-up satellite archival tags (PSATs) offer other opportunities, as they provide positions at pre-programmed times and collect on-route data, which can be used to describe position, behavior, and habitat ...
    • Variability and quasi-decadal changes in the methane budget over the period 2000-2012 

      Saunois, Marielle; Bousquet, Philippe; Poulter, Ben; Peregon, Anna; Ciais, Philippe; Canadell, Josep G; Dlugokencky, Edward J; Etiope, Giuseppe; Bastviken, David; Houweling, Sander; Janssens-Maenhout, Greet; Tubiello, Francesco N; Castaldi, Simona; Jackson, Robert B; Alexe, Mihai; Arora, Vivek K; Beerling, David J; Bergamaschi, Peter; Blake, Donald R; Brailsford, Gordon; Bruhwiler, Lori; Crevoisier, Cyril; Crill, Patrick; Covey, Kristofer; Frankenberg, Christian; Gedney, Nicola; Hoglund-Isaksson, Lena; Ishizawa, Misa; Ito, Akihiko; Joos, Fortunat; Kim, Heon-Sook; Kleinen, Thomas; Krummel, Paul; Lamarque, Jean-Francois; Langenfelds, Ray; Locatelli, Robin; Machida, Toshinobu; Maksyutov, Shamil; Melton, Joe R; Morino, Isamu; Naik, Vaishali; O'Doherty, Simon; Parmentier, Frans-Jan W.; Patra, Prabir K; Peng, Changhui; Peng, Shushi; Peters, Glen P; Pison, Isabelle; Prinn, Ronald; Ramonet, Michel; Riley, William J; Saito, Makoto; Santini, Monia; Schroeder, Ronny; Simpson, Isobel J; Spahni, Renato; Takizawa, Atsushi; Thornton, Brett F; Tian, Hanqin; Tohjima, Yasunori; Viovy, Nicolas; Voulgarakis, Apostolos; Weiss, Ray; Wilton, David J; Wiltshire, Andy; Worthy, Doug; Wunch, Debra; Xu, Xiyan; Yoshida, Yukio; Zhang, Bowen; Zhang, Zhen; Zhu, Qiuan (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-20)
      Following the recent Global Carbon Project (GCP) synthesis of the decadal methane (CH<sub>4</sub> budget over 2000– 2012 (Saunois et al., 2016), we analyse here the same dataset with a focus on quasi-decadal and inter-annual variability in CH<sub>4</sub> emissions. The GCP dataset integrates results from topdown studies (exploiting atmospheric observations within an atmospheric inverse-modelling ...
    • Variability in Calanus spp. abundance on fine- to mesoscales in an Arctic fjord: implications for little auk feeding 

      Vogedes, Daniel Ludwig; Eiane, Ketil; Båtnes, Anna Solvang; Berge, Jørgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Variable individual- and population- level responses to ocean acidification 

      Vihtakari, Mikko; Havenhand, Jon; Renaud, Paul; Hendriks, Iris E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-04-29)
      Population responses to marine climate change are determined by the strength of the selection pressure imposed by changing climate, the genetic variability within the population (i.e., among individuals), and phenotypic plasticity within individuals. Marine climate change research has focused primarily on population-level responses, yet it is at the level of the individual that natural selection ...
    • Variable responses of carbon and nitrogen contents in vegetation and soil to herbivory and warming in high-Arctic tundra 

      Petit Bon, Matteo; Bøhner, Hanna; Bråthen, Kari Anne; Ravolainen, Virve; Jónsdóttir, Ingibjörg Svala (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-21)
      Chemical responses of tundra vegetation and tundra soil to environmental changes are likely to differ, with implications for ecosystem functioning, yet they are rarely compared. Here, we aimed at comparing sensitivity and magnitude of short-term carbon and nitrogen responses of three main tundra ecosystem compartments: vascular plants, mosses, and soil, to two environmental perturbations: herbivore ...
    • Variation in functional trait composition of benthic invertebrates across depths and seasons in a subarctic lake 

      Frainer, André; Johansen, Kristin M. Sommerseth; Siwertsson, Anna; Mousavi, Seyed Ali; Brittain, John Edward; Klemetsen, Anders; Knudsen, Rune; Amundsen, Per-Arne (Journal article; Tidsskriftartikkel, 2016-07-01)
      Benthic invertebrate communities play a fundamental role in lake ecosystems, and the understanding of how those benthic communities are structured, particularly in terms of the identity and spatiotemporal distribution of their functional traits, is key to our understanding of how lake ecosystems work. In Takvatn, a subarctic lake in northern Norway, we identified the taxonomic and functional identity ...
    • Velferdskriterier i reindriften 

      Jørgensen, Grete Helen Meisfjord; Mejdell, Cecilie Marie; Stubsjøen, Solveig Marie; Ozkan, Seyda; Rødbotten, Rune; Bårdsen, Bård-Jørgen; Rødven, Rolf (Research report; Forskningsrapport, 2017-06-07)
      Formålet med prosjektet var å identifisere ulike faktorer som kunne påvirke velferd hos tamrein, og som kunne implementeres i produksjonssystemene, på beite, i gjerdet, på slakteriet, gjennom produktmerking og fremtidige kvalitetssikringssystemer. I den senere tid har det vært et økt fokus på dyrehelse og -velferd i reindrifta. Det har for eksempel vært et fokus på lave slaktevekter, spesielt i ...
    • Vertical export of marine pelagic protists in an ice-free high-Arctic fjord (Adventfjorden, West Spitsbergen) throughout 2011-2012 

      Marquardt, Miriam; Skogseth, Ragnheid; Wiedmann, Ingrid; Vader, Anna; Reigstad, Marit; Cottier, Finlo Robert; Gabrielsen, Tove M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-06)
      The ecosystem role of Arctic microbial communities is still largely unknown. Based on a time-series study at the IsA station (West Spitsbergen), the seasonality and contribution of pelagic protists to the vertical flux was investigated at 7 time points during 2011-2012. The hydrography of this high-Arctic fjord was evaluated to identify impacts on the community composition during the different ...
    • Vertical fluxes of nitrate in the seasonal nitracline of the Atlantic sector of the Arctic Ocean 

      Randelhoff, Achim; Fer, Ilker; Sundfjord, Arild; Tremblay, Jean-Éric; Reigstad, Marit (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-07-31)
      <p>This study compiles colocated oceanic observations of high-resolution vertical profiles of nitrate concentration and turbulent microstructure around the Svalbard shelf slope, covering both the permanently ice-free Fram Strait and the pack ice north of Svalbard. The authors present an overview over the seasonal evolution of the distribution of nitrate and its relation to upper ocean stratification. ...
    • Vertical movements of Atlantic salmon postsmolts relative to measures of salinity and water temperature during the first phase of the marine migration 

      Davidsen, Jan Grimsrud; Plantalech Manel-la, Nuria; Thorstad, E.B; Økland, F.; Sivertsgård, Rolf; McKinley, R.S; Finstad, B. (Journal article; Tidsskriftartikkel; Peer reviewed, 2009)
      The migratory behaviour of hatchery-reared Atlantic salmon, Salmo salar L., post-smolts during the first phase of the marine migration was examined to assess their susceptibility to salmon lice, Lepeophtheirus salmonis (Krøyer), infestations. Swimming depths of eight post-smolts relative to the measured salinity and temperature were monitored for an average of 11.4 h following release outside the ...
    • Vertical redistribution of principle water masses on the Northeast Greenland Shelf 

      Gjelstrup, Caroline V.B.; Sejr, Mikael K.; de Steur, Laura; Schou Christiansen, Jørgen; Granskog, Mats A.; Koch, Boris P.; Møller, Eva Friis; Winding, Mie H.S.; Stedmon, Colin A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-10)
      The Northeast Greenland shelf (NEGS) is a recipient of Polar Water (PW) from the Arctic Ocean, Greenland Ice Sheet melt, and Atlantic Water (AW). Here, we compile hydrographical measurements to quantify long-term changes in fjords and coastal waters. We find a profound change in the vertical distribution of water masses, with AW shoaling >60 m and PW thinning >50 m since early 2000’s. The properties ...