Viser treff 201-220 av 2040

    • Nutritious and delicious? A non-invasive study of food plant choices by Svalbard reindeer in Summer and late Autumn 

      Eikeland, Oline (Master thesis; Mastergradsoppgave, 2023-12-05)
      Seasonality affects growing patterns of vegetation and habitat use by herbivores. Short growing seasons make plants grow quickly through phenological stages which alters their nutrient levels and thus habitat use of herbivores that depend on energy assimilation in summer. Selective foraging that increases intake of high-quality forage can be highly advantageous and is usually a trade-off between ...
    • Drivers of mercury accumulation over the ontogeny of perch (Perca fluviatilis) in the subarctic Pasvik watercourse 

      Fredriksen, Julie (Master thesis; Mastergradsoppgave, 2023-11-15)
      Understanding drivers of mercury (Hg) accumulation in freshwater food webs is vital due to its ability to accumulate in organisms and magnify in food webs to potent levels, potentially impacting wildlife and human health. This is of particular concern in regions where fish serve as an important food source. This study explores drivers of Hg accumulation in European perch (Perca fluviatilis) across ...
    • Long-Term Effects on Somatic Growth, Life History Traits and Population Biology of Arctic Charr (Salvelinus alpinus) Following the Fish Culling Experiment in Takvatn 

      Indrebø, Synne Nan (Master thesis; Mastergradsoppgave, 2023-11-14)
      Stunting in fish populations is a special case of density-dependent growth characterized by old slow-growing individuals with low recreational and resource use value. The phenomenon is commonly observed in lacustrine populations of Arctic charr (Salvelinus alpinus) in temperate regions. In Takvatn, a subarctic lake in northern Norway, stunted growth of Arctic charr was attributed to food shortage ...
    • Drivers of an unexpected unimodal vertical pattern in size distribution of intertidal blue mussels (Mytilus spp.) 

      Sellæg, Victoria Eggen (Master thesis; Mastergradsoppgave, 2023-11-14)
      Blue mussels (Mytilus spp.) are important ecosystem bioengineers and provide numerous of ecosystem services. They are found worldwide, but face a global population decline for unclear reasons in many regions. A pilot study in the subarctic rocky intertidal shore in Northern Norway revealed an unexpected unimodal pattern in the body size of blue mussels along a vertical transect from low to high ...
    • Development and calibration of a high dynamic range and autonomous ocean-light instrument to measure sub-surface profiles in ice-covered waters 

      Schartmuller, Bernhard; Anderson, Philip; Mckee, David; Connan-McGinty, Stacey; Kopec, Tomasz Piotr; Daase, Malin Hildegard Elisabeth; Johnsen, Geir; Berge, Jørgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-23)
      The optical chain and logger (OptiCAL) is an autonomous ice-tethered observatory equipped with multiple light sensors for mapping the variation of light with depth. We describe the instrument and present an ensemble calibration for downwelling irradiance E<sub>PAR</sub> in [µmolm<sup>−2</sup>s<sup>−1</sup>]. Results from a long-term deployment in the Arctic Ocean demonstrate that the OptiCAL can ...
    • Biogeography of microbial communities in high-latitude ecosystems: Contrasting drivers for methanogens, methanotrophs and global prokaryotes 

      Seppey, Victor William Christophe; Cabrol, Léa; Thalasso, Frederic; Gandois, Laure; Lavergne, Céline; Martinez-Cruz, Karla; Sepulveda-Jauregui, Armando; Aguilar-Muñoz, Polette; Astorga-España, María Soledad; Chamy, Rolando; Dellagnezze, Bruna Martins; Etchebehere, Claudia; Fochesatto, Gilberto J.; Gerardo-Nieto, Oscar; Mansilla, Andrés; Murray, Alison; Sweetlove, Maxime; Tananaev, Nikita; Teisserenc, Roman; Tveit, Alexander Tøsdal; Van de Putte, Anton; Svenning, Mette Marianne; Barret, Maialen (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-27)
      Methane-cycling is becoming more important in high-latitude ecosystems as global warming makes permafrost organic carbon increasingly available. We explored 387 samples from three high-latitudes regions (Siberia, Alaska and Patagonia) focusing on mineral/organic soils (wetlands, peatlands forest), lake/pond sediment and water. Physicochemical, climatic and geographic variables were integrated ...
    • Cuscuta campestris fine-tunes gene expression during haustoriogenesis as an adaptation to different hosts 

      Bawin, Thomas Georges A; Didriksen, Alena; Faehn, Corine Alexis; Olsen, Stian; Sørensen, Iben; Rose, Jocelyn KC; Krause, Kirsten (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-14)
      The Cuscuta genus comprises obligate parasitic plants that have an unusually wide host range. Whether Cuscuta uses different infection strategies for different hosts or whether the infection strategy is mechanistically and enzymatically conserved remains unknown. To address this, we investigated molecular events during the interaction between field dodder (Cuscuta campestris) and two host species ...
    • Model-informed classification of broadband acoustic backscatter from zooplankton in an in situ mesocosm 

      Dunn, Muriel Barbara; McGowan-Yallop, Chelsey; Pedersen, Geir; Falk-Petersen, Stig; Daase, Malin Hildegard Elisabeth; Last, Kim; Langbehn, Tom; Fielding, Sophie; Brierley, Andrew S.; Cottier, Finlo Robert; Basedow, Sünnje Linnéa; Camus, Lionel; Geoffroy, Maxime (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-07)
      Classification of zooplankton to species with broadband echosounder data could increase the taxonomic resolution of acoustic surveys and reduce the dependence on net and trawl samples for ‘ground truthing’. Supervised classification with broadband echosounder data is limited by the acquisition of validated data required to train machine learning algorithms (‘classifiers’). We tested the hypothesis ...
    • Impacts of a warming climate on concentrations of organochlorines in a fasting high arctic marine bird: Direct vs. indirect effects? 

      Bustnes, Jan Ove; Bårdsen, Bård-Jørgen; Moe, Børge; Herzke, Dorte; Ballesteros, Manuel; Fenstad, Anette; Borgå, Katrine; Krogseth, Ingjerd Sunde; Eulaers, Igor; Skogeng, Lovise Pedersen; Gabrielsen, Geir Wing; Hanssen, Sveinn Are (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-30)
      The present study examined how climate changes may impact the concentrations of lipophilic organochlorines (OCs) in the blood of fasting High Arctic common eiders (Somateria mollissima) during incubation. Polychlorinated biphenyls (PCBs), 1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p′-DDE), hexachlorobenzene (HCB) and four chlordane compounds (oxychlordane, trans-chlordane and trans- and ...
    • The positive effect of plant diversity on soil carbon depends on climate 

      Spohn, Marie; Bagchi, Sumanta; Biederman, Lori A.; Borer, Elizabeth T.; Braathen, Kari Anne; Bugalho, Miguel N.; Caldeira, Maria C.; Catford, Jane A.; Collins, Scott L.; Eisenhauer, Nico; Hagenah, Nicole; Haider, Sylvia; Hautier, Yann; Knops, Johannes M. H.; Koerner, Sally E.; Laanisto, Lauri; Lekberg, Ylva; Martina, Jason P.; Martinson, Holly; McCulley, Rebecca L.; Peri, Pablo L.; Macek, Petr; Power, Sally A.; Risch, Anita C.; Roscher, Christiane; Seabloom, Eric W.; Stevens, Carly; Veen, G. F. (Ciska); Virtanen, Risto; Yahdjian, Laura (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-19)
      Little is currently known about how climate modulates the relationship between plant diversity and soil organic carbon and the mechanisms involved. Yet, this knowledge is of crucial importance in times of climate change and biodiversity loss. Here, we show that plant diversity is positively correlated with soil carbon content and soil carbon-to-nitrogen ratio across 84 grasslands on six continents ...
    • Still Arctic? — The changing Barents Sea 

      Gerland, Sebastian; Ingvaldsen, Randi Brunvær; Reigstad, Marit; Sundfjord, Arild; Bogstad, Bjarte; Chierici, Melissa; Hop, Haakon; Renaud, Paul Eric; Smedsrud, Lars Henrik; Stige, Leif Christian; Årthun, Marius; Berge, Jørgen; Bluhm, Bodil Annikki Ulla Barbro; Borgå, Katrine; Bratbak, Gunnar; Divine, Dmitry V; Eldevik, Tor; Eriksen, Elena; Fer, Ilker; Fransson, Agneta; Gradinger, Rolf Rudolf; Granskog, Mats A.; Haug, Tore; Husum, Katrine; Johnsen, Geir; Jonassen, Marius Opsanger; Jørgensen, Lis Lindal; Kristiansen, Svein; Larsen, Aud; Lien, Vidar Surén; Lind, Sigrid; Lindstrøm, Ulf Ove; Mauritzen, Cecilie; Melsom, Arne; Mernild, Sebastian H.; Müller, Malte; Nilsen, Frank; Primicerio, Raul; Søreide, Janne; van der Meeren, Gro Ingleid; Wassmann, Paul (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-13)
      The Barents Sea is one of the Polar regions where current climate and ecosystem change is most pronounced. Here we review the current state of knowledge of the physical, chemical and biological systems in the Barents Sea. Physical conditions in this area are characterized by large seasonal contrasts between partial sea-ice cover in winter and spring versus predominantly open water in summer and ...
    • Diffusive and advective cross-frontal fluxes of inorganic nutrients and dissolved inorganic carbon in the Barents Sea in autumn 

      Koenig, Zoe Charlotte; Fer, Ilker; Chierici, Melissa; Fransson, Agneta; Jones, Elizabeth Marie; Kolås, Eivind Hugaas (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-21)
      The Atlantic Water, entering the Arctic through the Barents Sea and Fram Strait, is the main source of nutrients in the Arctic Ocean. The Barents Sea is divided by the Polar Front into an Atlantic-dominated domain in the south, and an Arctic-dominated domain in the north. The Polar Front is a thermohaline structure, which is topographically-steered at sub-surface, and influenced by the seasonal ...
    • Hydrography, inorganic nutrients and chlorophyll a linked to sea ice cover in the Atlantic Water inflow region north of Svalbard 

      Renner, Angelika; Bailey, Allison Michelle; Reigstad, Marit; Sundfjord, Arild; Chierici, Melissa; Jones, Elizabeth Marie (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-04)
      Changes in the inflow of Atlantic Water (AW) and its properties to the Arctic Ocean bring more warm water, contribute to sea ice decline, promote borealisation of marine ecosystems, and affect biological and particularly primary productivity in the Eurasian Arctic Ocean. One of the two branches of AW inflow follows the shelf break north of Svalbard, where it dominates oceanographic conditions, ...
    • Abrupt permafrost thaw triggers activity of copiotrophs and microbiome predators 

      Scheel, Maria; Zervas, Athanasios; Rijkers, Ruud; Tveit, Alexander Tøsdal; Ekelund, Flemming; Campuzano Jiménez, Francisco; Christensen, Torben R.; Jacobsen, Carsten S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-05)
      Permafrost soils store a substantial part of the global soil carbon and nitrogen. However, global warming causes abrupt erosion and gradual thaw, which make these stocks vulnerable to microbial decomposition into greenhouse gases. Here, we investigated the microbial response to abrupt in situ permafrost thaw. We sequenced the total RNA of a 1 m deep soil core consisting of up to 26 500-year-old permafrost ...
    • Atlantification influences zooplankton communities seasonally in the northern Barents Sea and Arctic Ocean 

      Wold, Anette; Hop, Haakon; Svensen, Camilla; Søreide, Janne; Assmann, Karen M.; Ormanzcyk, Mateusz; Kwaśniewski, Sławomir (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-29)
      The Barents Sea is undergoing rapid ocean warming with less sea ice and increased Atlantic inflow, shifting the pelagic ecosystem towards a more boreal one, a process referred to as Atlantification. While such changes have already been documented in the southern and central Barents Sea, less is known about the degree of Atlantification in the northern Barents Sea and Arctic Ocean. In this seasonal ...
    • Horizon scanning of potential threats to high-Arctic biodiversity, human health and the economy from marine invasive alien species: A Svalbard case study 

      Cottier-Cook, Elizabeth Joanne; Bentley-Abbot, Jude; Cottier, Finlo Robert; Minchin, Dan; Olenin, Sergej; Renaud, Paul Eric (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-09)
      The high Arctic is considered a pristine environment compared with many other regions in the northern hemisphere. It is becoming increasingly vulnerable to invasion by invasive alien species (IAS), however, as climate change leads to rapid loss of sea ice, changes in ocean temperature and salinity, and enhanced human activities. These changes are likely to increase the incidence of arrival and ...
    • New insights into the Barents Sea Calanus glacialis population dynamics and distribution 

      Aarflot, Johanna Myrseth; Eriksen, Elena; Prokopchuk, Irina P.; Svensen, Camilla; Søreide, Janne; Wold, Anette; Skogen, Morten D. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-18)
      Arctic copepods are major grazers and vital food for planktivores in polar ecosystems but challenging to observe due to remoteness and seasonal sea ice coverage. Models offer higher spatio-temporal resolution, and individual-based models (IBMs) are useful since they incorporate individual variability which characterizes most copepod populations. Here, we present an IBM of the Arctic copepod Calanus ...
    • Skogens helsetilstand i Norge. Resultater fra skogskadeovervåkingen i 2022 

      Timmermann, Volkmar; Børja, Isabella; Clarke, Nicholas; Gohli, Jostein; Hietala, Ari Mikko; Jepsen, Jane Uhd; Krokene, Paal; Lislegård, Harald Haga; Nagy, Nina Elisabeth; Nyeggen, Hans; Solberg, Sverre; Solheim, Halvor; Solvin, Thomas Mørtvedt; Svensson, Arvid; Tollefsrud, Mari Mette; Vindstad, Ole Petter Laksforsmo; Økland, Bjørn; Aas, Wenche (Research report; Forskningsrapport, 2023-11-17)
      Skogens helsetilstand påvirkes i stor grad av klima og værforhold, enten direkte ved tørke, frost og vind, eller indirekte ved at klimaet påvirker omfanget av soppsykdommer og insektangrep. Klimaendringene og den forventede økningen i klimarelaterte skogskader gir store utfordringer for forvaltningen av framtidas skogressurser. Det samme gjør invaderende skadegjørere, både allerede etablerte arter ...
    • Modulation of intestinal growth and differentiation by photoperiod and dietary treatment during smoltification in Atlantic salmon (Salmo salar, L.) 

      Duarte, Vilma; Gaetano, Pasqualina; Striberny, Anja; Hazlerigg, David; Jørgensen, Even Hjalmar; Fuentes, Juan; Campinho, Marco A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-15)
      Atlantic salmon undergo smoltification, a process that prepares the fish to enter and thrive in seawater (SW). Several physiological changes occur during smolting, especially in osmoregulatory tissues, the gill, the kidney, and the intestine. Here we characterized the effects on intestinal morphogenesis of two different, commonly used smoltification regimes during the end of the freshwater phase, ...
    • Lack of strong seasonality in macrobenthic communities from the northern Barents Sea shelf and Nansen Basin 

      Jorda Molina, Eric; Sen, Arunima; Bluhm, Bodil Annikki Ulla Barbro; Renaud, Paul Eric; Włodarska-Kowalczuk, Maria; Legeżyńska, Joanna; Oleszczuk, Barbara; Reiss, Henning (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-12)
      The Barents Sea has been coined ‘the Arctic hotspot’ of climate change due to the rapidity with which environmental changes are taking place. This transitional domain from Atlantic to Arctic waters is home to highly productive benthic communities. This system strongly fluctuates on a seasonal basis in its sympagic-pelagicbenthic coupling interactions, with potential effects on benthic standing ...