Viser treff 1861-1880 av 2049

    • Settling-depth vs. genotype and size vs. genotype correlations at the Pan I locus in 0-group Atlantic cod Gadus morhua 

      Fevolden, Svein-Erik; Westgaard, Jon-Ivar; Pedersen, Torstein; Præbel, Kim (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      We sampled 0-group juvenile Atlantic cod Gadus morhua L. within fjords and offshore in northern Norway from 1994 to 2008 using different gears for the 3 sampling depths: shore seine (0−3 m), pelagic trawl (various depths), and bottom trawl (>80 m). Frequencies of alleles at the Pan I locus (4218 fish analysed) showed highly significant differences among samples collected in the different habitats. ...
    • Organic carbon transformations in high-Arctic peat soils: key functions and microorganisms 

      Tveit, Alexander Tøsdal; Schwacke, Rainer; Svenning, Mette Marianne; Urich, Tim (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      A substantial part of the Earths’ soil organic carbon (SOC) is stored in Arctic permafrost peatlands, which represent large potential sources for increased emissions of the greenhouse gases CH4 and CO2 in a warming climate. The microbial communities and their genetic repertoire involved in the breakdown and mineralisation of SOC in these soils are, however, poorly understood. In this study, we applied ...
    • Export stoichiometry and contribution of copepod faecal pellets to vertical flux of particulate organic carbon, nitrogen and phosphorus 

      Tamelander, Tobias; Aubert, Anais; Wexels Riser, Christian (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      Sinking of particles is a key mechanism in the transport of organic matter from the ocean’s productive surface layer to the deep sea and sediments, but also constitutes a loss of carbon and growth-limiting nutrients to the pelagic food web. Knowledge on export of particulate phosphorus is limited, particularly in high-latitude regions, in spite of its role as a co-limiting factor in many marine ...
    • Invasive red king crab affects lumpsucker recruitment by egg consumption 

      Mikkelsen, Nina; Pedersen, Torstein (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      The invasive red king crab Paralithodes camtschaticus preys on lumpsucker Cyclopterus lumpus eggs. We tested the hypothesis this egg consumption may hamper the recruitment of lumpsucker. Methods applied included field work, laboratory experiments and modelling of egg consumption. Crabs were sampled and feeding behaviour was studied by means of a remotely operated vehicle and SCUBA divers in a field ...
    • Plastid located WHIRLY1 enhances the responsiveness of Arabidopsis seedlings toward abscisic acid 

      Isemer, Rena; Krause, Kirsten; Grabe, Nils; Kitahata, Nobutaka; Asami, Tadao; Krupinska, Karin (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      WHIRLY1 is a protein that can be translocated from the plastids to the nucleus, making it an ideal candidate for communicating information between these two compartments. Mutants of Arabidopsis thaliana lacking WHIRLY1 (why1) were shown to have a reduced sensitivity toward salicylic acid (SA) and abscisic acid (ABA) during germination. Germination assays in the presence of abamine, an inhibitor of ...
    • Dual Targeting and Retrograde Translocation: Regulators of Plant Nuclear Gene Expression Can Be Sequestered by Plastids 

      Krause, Kirsten; Oetke, Svenja; Krupinska, Karin (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      Changes in the developmental or metabolic state of plastids can trigger profound changes in the transcript profiles of nuclear genes. Many nuclear transcription factors were shown to be controlled by signals generated in the organelles. In addition to the many different compounds for which an involvement in retrograde signaling is discussed, accumulating evidence suggests a role for proteins in ...
    • Protein genes in repetitive sequence—antifreeze glycoproteins in Atlantic cod genome 

      Zhuang, Xuan; Yang, Chun; Fevolden, Svein-Erik; Cheng, Chi-Hing Christina (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      Highly repetitive sequences are the bane of genome sequence assembly, and the short read lengths produced by current next generation sequencing technologies further exacerbates this obstacle. An adopted practice is to exclude repetitive sequences in genome data assembly, as the majority of repeats lack protein-coding genes. However, this could result in the exclusion of important genotypes in newly ...
    • Spring bloom dynamics in Kongsfjorden, Svalbard: nutrients, phytoplankton, protozoans and primary production 

      Hodal, helene; Kristiansen, Svein; Hop, Haakon; Falk-Petersen, Stig; Reigstad, Marit (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      The marine ecosystem in Kongsfjorden (79 N), a glacial fjord in Svalbard, is to a large extent well known with regard to hydrography, mesozooplankton and higher trophic levels. Research on primary production and lower trophic levels is still scare and especially investigations from winter and spring periods. The spring bloom dynamics in Kongsfjordenwere investigated in 2002. The development in ...
    • Potential misidentifications of two climate indicator species of the marine arctic ecosystem: Calanus glacialis and C. finmarchicus 

      Gabrielsen, Tove M; Merkel, Benjamin; Søreide, Janne; Johansson-Karlsson, Emma; Bailey, Allison; Vogedes, Daniel Ludwig; Nygård, Henrik Andreas; Varpe, Øystein; Berge, Jørgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      Calanoid copepods of the genus Calanus represent an important, nutrient-rich food source for a multitude of Arctic marine organisms. Although morphologically very similar, their life histories and ecological roles differ. Because the distribution of Calanus glacialis and C. finmarchicus corresponds to Arctic and Atlantic water masses, respectively, they are regularly used as climate indicators. A ...
    • Age-dependent genetic structure of arctic foxes in Svalbard 

      Ehrich, Dorothee; Carmichael, Lindsey; Fuglei, Eva (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
    • Evolution of the Arctic Calanus complex: an Arctic marine avocado? 

      Berge, Jørgen; Gabrielsen, Tove M; Moline, Mark A.; Renaud, Paul (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      Before man hunted the large baleen whales to near extinction by the end of the nineteenth century, Arctic ecosystems were strongly influenced by these large predators. Their main prey were zooplankton, among which the calanoid copepod species of the genus Calanus, long considered key elements of polar marine ecosystems, are particularly abundant. These herbivorous zooplankters display a range of ...
    • Bioluminescence in the high Arctic during the polar night 

      Berge, Jørgen; Båtnes, Anna Solvang; Johnsen, Geir; Blackwell, Susan; Moline, Mark A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      This study examines the composition and activity of the planktonic community during the polar night in the high Arctic Kongsfjord, Svalbard. Our results are the first published evidence of bioluminescence among zooplankton during the Arctic polar night. The observations were collected by a bathyphotometer detecting bioluminescence, integrated into an autonomous underwater vehicle, to determine the ...
    • New parasites and predators follow the introduction of two fish species to a subarctic lake: implications for food-web structure and functioning 

      Amundsen, Per-Arne; Lafferty, Kevin D.; Knudsen, Rune; Primicerio, Raul; Kristoffersen, Roar; Klemetsen, Anders; Kuris, Armand M (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      Introduced species can alter the topology of food webs. For instance, an introduction can aid the arrival of free-living consumers using the new species as a resource, while new parasites may also arrive with the introduced species. Food-web responses to species additions can thus be far more complex than anticipated. In a subarctic pelagic food web with free-living and parasitic species, two fish ...
    • Bird communities of the Arctic shrub tundra of Yamal: habitat specialists and generalists 

      Sokolov, Vasily; Ehrich, Dorothee; Yoccoz, Nigel; Sokolov, Alexander; Lecomte, Nicolas (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      The ratio of habitat generalists to specialists in birds has been suggested as a good indicator of ecosystem changes due to e.g. climate change and other anthropogenic perturbations. Most studies focusing on this functional component of biodiversity originate, however, from temperate regions. The Eurasian Arctic tundra is currently experiencing an unprecedented combination of climate change, change ...
    • What Do the IUCN Categories Really Protect? A Case from the Alpine Regions in Spain? 

      Muñoz, Lorena; Hausner, Vera Helene (Conference object; Konferansebidrag, 2012)
      The protected area (PA) coverage is used as an indicator of biodiversity protection worldwide. The effectiveness of using PAs as indicators has been questioned due to the diversity of designations included in such measures, especially those PAs established for other purposes than biodiversity protection. Although international standards have been developed by the International Union for Conservation ...
    • Community-Based Management: Under What Conditions Do Sámi Pastoralists Manage Pastures Sustainably? 

      Hausner, Vera Helene; Fauchald, Per; Jernsletten, Johnny-Leo L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      Abstract Community-based management (CBM) has been implemented in socio-ecological systems (SES) worldwide. CBM has also been the prevailing policy in Sa´mi pastoral SES in Norway, but the outcomes tend to vary extensively among resource groups (‘‘siidas’’). We asked why do some siidas self-organize to manage common pool resources sustainably and others do not? To answer this question we used a ...
    • Seasonal variations in the profundal Chironomidae (Diptera) assemblage of a subarctic lake. 

      Mousavi, Seyed Karim; Amundsen, Per-Arne (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      Zoobenthos samples were collected over a 12-month period in the profundal zone of the subarctic Fjellfrøsvatn, a lake in northern Norway. Chironomid larvae numerically dominated the profundal zoobenthos and their mean density decreased with increasing depth. Procladius (Holotanypus) sp. A, Mesocricotopus thienemanni, Psectrocladius (Mesopsectrocladius) sp. and Heterotrissocladius subpilosus exhibited ...
    • Frequency of local, regional, and long-distance dispersal of diploid and tetraploid Saxifraga oppositifolia (Saxifragaceae) to Arctic glacier forelands 

      Müller, Eike; Eidesen, Pernille Bronken; Ehrich, Dorothee; Alsos, Inger Greve (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      Climate change forces many species to migrate. Empirical small-scale data on migration and colonization in the Arctic are scarce. Retreating glaciers provide new territory for cold-adapted plant species, but the genetic consequences depend on dispersal distances and frequencies. We estimated local, regional, and long-distance dispersal frequencies, as well as their effect on levels of genetic ...
    • Collapse of an arctic bird community resulting from ungulate-induced loss of erect shrubs 

      Ims, Rolf Anker; Henden, John-André (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      Rapid, but contrasting, changes in the extent of erect thicket-forming shrubs is presently seen in the Arctic, either resulting from a warmer climate (increasing extent) or intensified herbivory (decreasing extent). We investigated the impact of loss of willow shrubs on a bird community in arctic riparian sediment plains in northern Norway subject to varying intensities of reindeer browsing. In ...
    • Spawning coloration and sperm quality in a large lake population of Arctic charr (Salmonidae: Salvelinus alpinus L.) 

      Janhunen, Matti; Rudolfsen, Geir; Kekäläinen, Jukka; Figenschou, Lars; Peuhkuri, Nina; Kortet, Raine (Journal article; Tidsskriftartikkel; Peer reviewed, 2009)
      The modern theories of sexual selection predict that male sexual ornaments may have evolved as reliable signals of male fertilization efficiency. However, among the studies of fishes with external fertilization, the results have yielded ambiguous evidence. In the present study, we present data on the phenotypic relationships between red spawning coloration and ejaculate quality (spermatocrit, sperm ...