Now showing items 1161-1180 of 2040

    • Towards a global arctic-alpine model for Near-infrared reflectance spectroscopy (NIRS) predictions of foliar nitrogen, phosphorus and carbon content 

      Murguzur, Francisco Javier Ancin; Bison, Marjorie; Smis, Adriaan; Bohner, Hanna; Struyf, Eric; Meire, Patrick; Bråthen, Kari Anne (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-04)
      Near-infrared spectroscopy (NIRS) is a high-throughput technology with potential to infer nitrogen (N), phosphorus (P) and carbon (C) content of all vascular plants based on empirical calibrations with chemical analysis, but is currently limited to the sample populations upon which it is based. Here we provide a first step towards a global arctic-alpine NIRS model of foliar N, P and C content. We ...
    • Effect of Antiviral Drugs against Cervid Herpesvirus 2 (CvHV2) in vitro 

      Magnuson, Emily Elizabeth (Master thesis; Mastergradsoppgave, 2018-11-15)
      Cervid herpesvirus 2 (CvHV2) is an alphaherpesvirus found in Rangifer subspecies throughout most of the circumpolar Arctic and the causative agent of infectious keratoconjunctivitis (IKC) in semi-domesticated Eurasian tundra reindeer (Rangifer tarandus tarandus). IKC occurs as regular outbreaks, affecting dozens of reindeer in a herd, and is most common and severe among calves and young animals. IKC ...
    • Yearly variation in allelopathic compound production along a climatic gradient. A case of study of Empetrum nigrum 

      Moriana Armendariz, Mikel (Master thesis; Mastergradsoppgave, 2017-11-15)
      Empetrum nigrum is a plant common in northern ecosystems with capacity to produce allelopathic compounds, which among other effects inhibit seed establishment and germination of other plants. Some of the most studied compounds regarding this effect are batatasin-III and phenolic acids, among them caffeic acid, which account for a large proportion of the leaf’s biomass. 5 random sites were established ...
    • Long-term ecological studies in northern lakes – challenges, experiences, and accomplishments 

      Amundsen, Per-Arne; Primicerio, Raul; Smalås, Aslak; Henriksen, Eirik Haugstvedt; Knudsen, Rune; Kristoffersen, Roar; Klemetsen, Anders (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-08-15)
      We review three long‐term research programs performed over the last four decades on the ecology and management of oligotrophic lake systems with different fish communities at 69&deg; N in Norway. Through whole‐lake perturbation experiments, intensive culling of stunted fish removed 35 tons (1984–1991) of Arctic charr <i>Salvelinus alpinus</i> in Takvatn (15 km<sup>2</sup>) and 153 tons (1981–1983, ...
    • Populasjonssykluser hos bjørkemålere – små dyr med enorme svingninger 

      Vindstad, Ole Petter Laksforsmo; Jepsen, Jane Uhd (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-27)
      Fjellbjørkemåler og liten frostmåler er to nattsommerfugler som har sykliske populasjonssvingninger i fjellbjørkeskogen i Skandinavia. Populasjonstopper kommer med omtrent ti års mellomrom, og tettheten av målere i toppår kan være flere tusen ganger høyere enn i bunnår. Selv om syklusene er godt beskrevet ved hjelp av lange tidsserier er årsaken til svingningene dårlig forstått. Antibeitestoffer hos ...
    • Earlier colony arrival but no trend in hatching timing in two congeneric seabirds (Uria spp.) across the North Atlantic 

      Merkel, Benjamin; Descamps, Sebastien; Yoccoz, Nigel Gilles; Danielsen, Jóhannis; Daunt, Francis; Erikstad, Kjell E; Ezhov, Aleksey V.; Grémillet, David; Gavrilo, Maria; Lorentsen, Svein Håkon; Reiertsen, Tone Kristin; Steen, Harald; Systad, Geir Helge Rødli; Þórarinsson, Þorkell Lindberg; Wanless, Sarah; Strøm, Hallvard (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-23)
      A global analysis recently showed that seabird breeding phenology (as the timing of egg-laying and hatching) does not, on average, respond to temperature changes or advance with time (Keogan <i>et al.</i> 2018 <i>Nat. Clim. Change</i> <b>8</b>, 313–318). This group, the most threatened of all birds, is therefore prone to spatio-temporal mismatches with their food resources. Yet, other aspects of ...
    • An effective method for the recapture of escaped farmed salmon 

      Chittenden, Cedar; Rikardsen, Audun H.; Skilbrei, Ove Tommy; Davidsen, Jan Grimsrud; Halttunen, Elina; Skardhamar, Jofrid; McKinley, R. Scott (Journal article; Tidsskriftartikkel; Peer reviewed, 2011-04-04)
      The search for effective strategies to prevent and mitigate accidental releases of aquaculture fishes is on-going. To test a new recapture strategy and evaluate the individual dispersal behaviour of escaped farmed Atlantic salmon <i>Salmo salar</i> L. at the northern limit of its range, 39 adult salmon (mean ± SD fork length and weight: 85.5 ± 5.0 cm and 7.4 ± 1.4 kg, respectively) were implanted ...
    • Resource polymorphism in European whitefish: Analysis of fatty acid profiles provides more detailed evidence than traditional methods alone 

      Thomas, Stephen M; Kainz, Martin J.; Amundsen, Per-Arne; Hayden, Brian; Taipale, Sami Johan; Kahilainen, Kimmo Kalevi (Journal article; Peer reviewed, 2019-08-20)
      Resource polymorphism—whereby ancestral generalist populations give rise to several specialised morphs along a resource gradient—is common where species colonise newly formed ecosystems. This phenomenon is particularly well documented in freshwater fish populations inhabiting postglacial lakes formed at the end of the last ice age.<br> However, knowledge on how such differential exploitation of ...
    • Ocean predation and mortality of adult Atlantic salmon 

      Strøm, John Fredrik; Rikardsen, Audun H.; Campana, Steven E.; Righton, David; Carr, Jonathan; Aarestrup, Kim; Stokesbury, Michael J.W.; Gargan, Patrick G.; Caballero Javierre, Pablo; Thorstad, Eva Bonsak (Journal article; Peer reviewed, 2019-05-27)
      Predation and mortality are often difficult to estimate in the ocean, which hampers the management and conservation of marine fishes. <br>We used data from pop-up satellite archival tags to investigate the ocean predation and mortality of adult Atlantic salmon (Salmo salar) released from 12 rivers flowing into the North Atlantic Ocean. Data from 156 tagged fish revealed 22 definite predation ...
    • Diversity and Distribution of Meroplanktonic Larvae in the Pacific Arctic and Connectivity With Adult Benthic Invertebrate Communities 

      Ershova, Elizaveta; Descôteaux, Raphaëlle; Wangensteen, Owen; Iken, Katrin; Hopcroft, Russ; Smoot, Caitlin; Grebmeier, Jacqueline M.; Bluhm, Bodil (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-13)
      Pelagic larval stages (meroplankton) of benthic invertebrates seasonally make up a significant proportion of planktonic communities, as well as determine the distribution of their benthic adult stages, yet are frequently overlooked by both plankton and benthic studies. Within the Arctic, the role of meroplanktonic larvae may be particularly important in regions of inflow from sub-Arctic regions, ...
    • Recolonization and succession of a subtidal hard-bottom epibenthic community in Smeerenburgfjorden, NW Svalbard. 

      Keck, Amalia (Master thesis; Mastergradsoppgave, 2018-05-15)
      Rapid changes to the physical environment of Arctic marine systems in recent years impact the structure and function of benthic ecosystems. Exploring the resilience of these systems to perturbations requires a solid understanding of key ecological processes and must be conducted over appropriate time scales due to the slow growth and recruitment of many Arctic benthic organisms. This study addresses ...
    • The role of gill raker number variability in adaptive radiation of coregonid fish 

      Kahilainen, Kimmo; Siwertsson, Anna; Gjelland, Karl Øystein; Knudsen, Rune; Bøhn, Thomas; Amundsen, Per-Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2010-07-27)
      Gill raker divergence is a general pattern in adaptive radiations of postglacial fish, but few studies have addressed the adaptive significance of this morphological trait in foraging and eco-evolutionary interactions among predator and prey. Here, a set of subarctic lakes along a diversifying gradient of coregonids was used as the natural setting to explore correlations between gill raker numbers ...
    • Prevalence of antibodies against Brucella spp. in West Greenland polar bears (Ursus maritimus) and East Greenland muskoxen (Ovibos moschatus) 

      Sonne, Christian; Andersen-Ranberg, Emilie; Rajala, Elisabeth; Agerholm, Jørgen S.; Bonefeld-Jørgensen, Eva; Desforges, Jean-Pierre; Eulaers, Igor; Gustavson, Kim; Jenssen, Bjørn Munro; Koch, Anders; Rosing-Asvid, Aqqalu; Schmidt, Nils Martin; Grøndahl, Carsten; Mosbacher, Jesper Bruun; Siebert, Ursula; Tryland, Morten; Mulvad, Gert; Born, Erik W; Laidre, Kristin; Wiig, Øystein; Dietz, Rune; Magnusson, Ulf (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-19)
      Zoonotic infections transmitted from terrestrial and marine mammals to humans in European Arctic are of unknown significance, despite considerable potential for transmission due to local hunt and a rapidly changing environment. As an example, infection with <i>Brucella</i> bacteria may have significant impact on human health due to consumption of raw meat or otherwise contact with tissues and fluids ...
    • Arctic marine fungi: biomass, functional genes, and putative ecological roles 

      Hassett, Brandon Thomas; Borrego, Eli; Vonnahme, Tobias R.; Rämä, Teppo; Kolomiets, M.V.; Gradinger, Rolf (Journal article; Peer reviewed, 2019-02-11)
      Recent molecular evidence suggests a global distribution of marine fungi; however, the ecological relevance and corresponding biological contributions of fungi to marine ecosystems remains largely unknown. We assessed fungal biomass from the open Arctic Ocean by applying novel biomass conversion factors from cultured isolates to environmental sterol and CARD-FISH data. <br>We found an average of ...
    • Food web functions and interactions during spring and summer in the arctic water inflow region: Investigated through inverse modeling 

      Olli, Kalle; Halvorsen, Elisabeth; Vernet, Maria; Lavrentyev, Peter J.; Franzè, Gayantonia; Sanz-Martín, Marina; Paulsen, Maria Lund; Reigstad, Marit (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-28)
      We used inverse modeling to reconstruct major planktonic food web carbon flows in the Atlantic Water inflow, east and north of Svalbard during spring (18–25 May) and summer (9–13 August), 2014. The model was based on three intensively sampled stations during both periods, corresponding to early, peak, and decline phases of a <i>Phaeocystis</i> and diatom dominated bloom (May), and flagellates dominated ...
    • Sero-prevalence of brucellosis among slaughterhouse workers in Bahr el Ghazal region, South Sudan 

      Madut, Nuol Aywel; Ocan, Moses; Muwonge, Adrian; Muma, John Bwalya; Nasinyama, George William; Godfroid, Jacques; Jubara, Ambrose Samuel; Kankya, Clovice (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-22)
      <i>Background</i> - Brucellosis is an infectious zoonotic disease and is common especially among pastoral communities in most low and middle-income countries. The aim of this study was to determine sero-prevalence, and risk factors of Brucella infection among Slaughterhouse workers, in Bahr el Ghazal region, South Sudan.<p> <p><i>Methods</i> - A cross sectional study was conducted among Slaughterhouse ...
    • A first fecundity study of the female snow crab Chionoecetes opilio Fabricius, 1788 (Decapoda: Brachyura: Oregoniidae) of the newly established population in the Barents Sea 

      Danielsen, Hanna Ellerine Helle; Hjelset, Ann Merete; Bluhm, Bodil; Hvingel, Carsten; Agnalt, Ann-Lisbeth (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-11)
      The snow crab <i>Chionoecetes opilio</i> Fabricius, 1788 is a newly established species in the Barents Sea. Since the first individuals were recorded in 1996, the population has increased and a fishery was initiated in 2012. Mature female snow crab caught in the central Barents Sea were investigated with regards to fecundity. Ovigerous females (<i>N</i> = 185) ranged from 48 to 100 mm carapace width ...
    • Improved Environmental Status: 50 Years of Declining Fish Mercury Levels in Boreal and Subarctic Fennoscandia 

      Braaten, Hans Fredrik Veiteberg; Åkerblom, Staffan; Kahilainen, Kimmo Kalevi; Rask, Martti; Vuorenmaa, Jussi; Mannio, Jaakko; Malinen, Tommi; Lydersen, Espen; Poste, Amanda; Amundsen, Per-Arne; Kashulin, Nikolai; Kashulina, Tatiana; Terentjev, Petr; Christensen, Guttorm; de Wit, Heleen (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-14)
      Temporally (1965–2015) and spatially (55°–70°N) extensive records of total mercury (Hg) in freshwater fish showed consistent declines in boreal and subarctic Fennoscandia. The database contains 54 560 fish entries (n: pike > perch ≫ brown trout > roach ≈ Arctic charr) from 3132 lakes across Sweden, Finland, Norway, and Russian Murmansk area. 74% of the lakes did not meet the 0.5 ppm limit to protect ...
    • Transcriptomic analysis reveals dose-dependent modes of action of benzo(a)pyrene in polar cod (Boreogadus saida) 

      Song, You; Nahrgang, Jasmine; Tollefsen, Knut Erik (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-21)
      Polar cod (<i>Boreogadus saida</i>) has been used as a model Arctic species for hazard assessment of environmental stressors such as polycyclic aromatic hydrocarbons (PAHs). However, most of the PAH studies using polar cod rely on targeted biomarker-based analysis thus may not adequately address the complexity of the toxic mechanisms of the stressors. The present study was performed to develop a ...
    • Infectious Disease Outbreak Associated with Supplementary Feeding of Semi-Domesticated Reindeer 

      Tryland, Morten; Nymo, Ingebjørg Helena; Sanchez Romano, Javier; Mørk, Torill; Klein, Joern; Rockström, Ulrika (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-18)
      Supplementary winter feeding of semi-domesticated reindeer (<i>Rangifer tarandus tarandus</i>) has become more common in Sweden and Norway due to reindeer pasture fragmentation and climatic conditions. With increased corralling and feeding, often associated with animal stress, increased animal-to-animal contact, and poor hygienic conditions, an altered range of health challenges and diseases may ...