Viser treff 1021-1040 av 2050

    • Can aquaculture impact the surrounding biodiversity? A metabarcoding assessment 

      Guri, Gledis (Master thesis; Mastergradsoppgave, 2020-06-01)
      World’s population growth and rise in food consumption per capita have led to increased food demand and overexploitation of natural resources in recent decades. Such increase has threatened the global feeding schemes to maintain a balance between food supply and demand. Although “The Blue Revolution” promised to fill such gap and simultaneously alleviate the overexploitation of the oceans, deterioration ...
    • Do the predators of Yamal have a learning effect of artificial nests? 

      Olsen, Dag Alexander Hultgren (Master thesis; Mastergradsoppgave, 2020-06-01)
      Many artificial nest studies that goes over several years place the nests in the same location each placement. Over the years there is a chance that the predators learn where the nests are placed and that can give skewed results. The goal of my study is to see if the predators learn where the nests are located. This was done over three study sites on the Yamal peninsula. In two of the study sites ...
    • eDNA metabarcoding of amoebic gill disease (AGD) pathogens exposes potential vectors and reservoirs 

      Mertz, Nathan (Master thesis; Mastergradsoppgave, 2020-05-31)
      Aquaculture worldwide is under constant scrutiny and financial pressure to maintain fish health, while providing an essential food source to a growing populace. To assist in monitoring mariculture sites and preventing harmful diseases, we tested a recently proposed method of trace pathogen detection using eDNA metabarcoding. The target pathogen, Paramoeba perurans, is the etiological agent of AGD, ...
    • The Demersal Fish Community on the West Spitsbergen Shelf. Biodiversity, species composition, distribution and temporal changes in relation to climate. 

      Born, Mathea (Master thesis; Mastergradsoppgave, 2020-05-29)
      This thesis explores a historical time series of trawl stations on the West Spitsbergen Shelf (WSS), aiming to understand the spatial and temporal variability of the demersal fish communities in the region. Abundance data of 42 fish species are used to investigate the species composition, richness, and diversity across six different areas under different environmetal influence. The results indicate ...
    • Interannual variability (2014-2019) of hydrography, fluorescence and nutrient distribution in Vestfjorden, Lofoten 

      Fernández Román, Daniel (Master thesis; Mastergradsoppgave, 2020-06-01)
      Vestfjorden is an area of great ecological relevance since it is one of the main spawning areas of North East Atlantic cod. The survival rate of the cod larvae depends greatly on the abundance of zooplankton, which in turn depends on phytoplankton. Due to the extreme seasonality of high latitude fjords with a short productive season, understanding the phytoplankton distribution in spring is crucial. ...
    • Dietary vs. light stimulated smoltification: effects on smolt development and appetite regulation in pre- and post- smolts 

      Jansen, Melissa (Master thesis; Mastergradsoppgave, 2020-05-22)
      The transfer of smolt from freshwater (FW) to seawater (SW) is a critical stage in the farming of Atlantic salmon (Salmo salar) with mortalities of up to 15 % after transfer. One of the reasons for this loss is suboptimal smolt quality. It is therefore important to ensure that the fish are fully SW adapted before transfer to SW. Traditionally, smoltification is stimulated by exposing the fish to a ...
    • Analysis of xyloglucan-modifying genes and enzymes at graft-junctions of tomato plants 

      Lundblad, Herman (Master thesis; Mastergradsoppgave, 2020-05-16)
      Grafting is a widely used technique for propagation of plants in both agriculture and horticulture worldwide and involves combining two or more plants into one chimeric plant, ultimately with a shared vascular system. Benefits of grafting such as pathogen resistance, increase in fruit yield and abiotic stress tolerance have long been known, but the biological mechanisms of how plants graft are still ...
    • Addressing the aquatic vertebrate community of Vågsfjorden 2019 with the use of Environmental DNA 

      Mikalsen, Simeon Jonatan (Master thesis; Mastergradsoppgave, 2020-05-15)
      In order to estimate biodiversity or do species counts, detramental techniques such as trawling or longlining have been used. Lately techniques used to monitor, such as baited remote underwater video systems and environmental DNA have been tested as possible methods to investigate species richness and abundance, the latter which will be used in this thesis. Using eDNA methodology, a northern ...
    • Genetic population structure of the northern shrimp (Pandalus borealis) along the Norwegian coast 

      Hansen, Agneta (Master thesis; Mastergradsoppgave, 2020-05-15)
      The coastal shrimp (Pandalus borealis) represent an important income for a small-scale fishery. The more economical important fishery of shrimp is located offshore. There is sparse information and literature regarding the coastal shrimp, and it is a lot we do not know about the species that inhabits our coast and fjords. Genetic research will provide more information on the species in these areas. ...
    • High Arctic ecosystem states: Conceptual models of vegetation change to guide long-term monitoring and research 

      Ravolainen, Virve; Soininen, Eeva Marjatta; Jónsdóttir, Ingibjörg Svala; Eischeid, Isabell; Forchhammer, Mads C.; van der Wal, René; Pedersen, Åshild Ønvik (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-18)
      Vegetation change has consequences for terrestrial ecosystem structure and functioning and may involve climate feedbacks. Hence, when monitoring ecosystem states and changes thereof, the vegetation is often a primary monitoring target. Here, we summarize current understanding of vegetation change in the High Arctic—the World’s most rapidly warming region—in the context of ecosystem monitoring. To ...
    • Arctic Observations Identify Phytoplankton Community Composition as Driver of Carbon Flux Attenuation 

      Wiedmann, Ingrid; Ceballos-Romero, E.; Villa-Alfageme, M.; Renner, Angelika; Dybwad, Christine; van der Jagt, Helga; Svensen, Camilla; Assmy, Philipp; Wiktor, Josef; Tatarek, Agnieszka; Różańska‐Pluta, M.; Iversen, Morten H. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-24)
      The attenuation coefficient <i>b</i> is one of the most common ways to describe how strong the carbon flux is attenuated throughout the water column. Therefore, <i>b</i> is an essential input variable in many carbon flux and climate models. Marsay et al. (2015, <a href=https://doi.org/10.1073/pnas.1415311112>https://doi.org/10.1073/pnas.1415311112</a>) proposed that the median surface water temperature ...
    • Interactions between winter and summer herbivory affect spatial and temporal plant nutrient dynamics in tundra grassland communities 

      Petit Bon, Matteo; Inga, Katarina Gunnarsdotter; Jónsdóttir, Ingibjörg Svala; Utsi, Tove Aagnes; Soininen, Eeva Marjatta; Bråthen, Kari Anne (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-27)
      In the long‐term, herbivores can alter nutrient dynamics in terrestrial ecosystems by changing the functional composition of plant communities. Here, we ask to what extent herbivores can affect plant‐community nutrient dynamics in the short‐term. We provide theoretical expectations for immediate effects of herbivores on tundra‐grassland plant‐community nutrient levels throughout a single growing ...
    • 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) ...
    • Gammaherpesvirus in Cervid Species from Norway: Characterization of a New Virus in Wild and Semi-Domesticated Eurasian Tundra Reindeer (Rangifer tarandus tarandus) 

      Das Neves, Carlos G; Sacristan, Carlos; Madslien, Knut Ivar Engesæter; Tryland, Morten (Journal article; Tidsskriftartikkel; Peer reviewed, 2020)
      Gammaherpesvirus infections have been described in cervids worldwide, mainly the genera <i>Macavirus</i> or <i>Rhadinovirus</i>. However, little is known about the gammaherpesviruses species infecting cervids in Norway and Fennoscandia. Blood samples from semi-domesticated (<i>n</i> = 39) and wild (<i>n</i> = 35) Eurasian tundra reindeer (<i>Rangifer tarandus tarandus</i>), moose (<i>Alces alces</i>, ...
    • One leaf for all: Chemical traits of single leaves measured at the leaf surface using near-infrared reflectance spectroscopy 

      Petit Bon, Matteo; Böhner, Hanna; Kaino, Sissel; Moe, Torunn; Bråthen, Kari Anne (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-10)
      1. The leaf is an essential unit for measures of plant ecological traits. Yet, measures of plant chemical traits are often achieved by merging several leaves, masking potential foliar variation within and among plant individuals. This is also the case with cost‐effective measures derived using near‐infrared reflectance spectroscopy (NIRS). The calibration models developed for converting NIRS spectral ...
    • Bearded seal vocalisations across seasons and habitat types in Svalbard (Norway) 

      Martínez Llobet, Samuel (Master thesis; Mastergradsoppgave, 2019-08-15)
      Male bearded seals use vocal displays to attract females and compete with other males during the mating period, making it possible to monitor breeding populations using passive acoustic monitoring (PAM). This study analysed year-round acoustic data from underwater recorders at three sites with different environmental conditions in Svalbard (Norway). Male bearded seals vocalised for an extended ...
    • An interannual study of foraging behaviour in sympatrically breeding macaroni Eudyptes chrysolophus and chinstrap penguins Pygoscelis antarcticus at Bouvetøya 

      Narvestad, Audun (Master thesis; Mastergradsoppgave, 2019-08-15)
      Species are likely to segregate their ecological niches to minimize competition for resources, but for centrally foraging predators that breed on sub-Antarctic islands in the Southern Ocean the possibility of niche segregation may be minimal. This study is the first to examine the spatial and trophic aspects of the foraging niche of sympatrically breeding macaroni and chinstrap penguins at the ...
    • Size‐and stage‐dependence in cause‐specific mortality of migratory brown trout 

      Nater, Chloe Rebecca; Vindenes, Yngvild; Aas, Per; Cole, Diana; Langangen, Øystein; Moe, S. Jannicke; Rustadbakken, Atle; Turek, Daniel; Vøllestad, Leif Asbjørn; Ergon, Torbjørn (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-29)
      <ol> <li>Evidence‐based management of natural populations under strong human influence frequently requires not only estimates of survival but also knowledge about how much mortality is due to anthropogenic vs. natural causes. This is the case particularly when individuals vary in their vulnerability to different causes of mortality due to traits, life history stages, or locations.</li> <li>Here, ...
    • Gyrodactylus triglopsi n. sp. (Monogenea: Gyrodactylidae) from the Gills of Triglops nybelini Jensen, 1944 (Teleostei: Cottidae) in the Barents Sea 

      Hansen, Haakon; Alvestad, Anja Helene; MacKenzie, Ken; Darrud, Mari; Karlsbakk, Egil; Hemmingsen, Willy; Arneberg, Per (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-28)
      <i>Introduction</i> - Monogeneans of the genus <i>Gyrodactylus</i> were found on the gills of specimens of the bigeye sculpin <i>Triglops nybelini</i> Jensen, 1944 caught by trawl in the Barents Sea in January–February 2016.<p> <p><i>Methods</i> - Morphological preparations of the parasites were examined and photographed under a microscope at magnifcations of×100–1000 and morphometric analyses ...
    • Denning phenology of polar bears (Ursus maritimus) in the Barents Sea population 

      Sulich, Joanna Maria (Master thesis; Mastergradsoppgave, 2019-07-31)
      Timing reproductive effort to match food availability is important due to high energetic costs of reproduction. Female polar bears need sufficient time in the den to nurse cubs until they are big enough to withstand the Arctic environment, however females’ emergence from the den needs to be synchronized with ringed seal pupping peak, which is a crucial energy source for polar bears. The phenology ...