• Arctic Ocean outflow shelves in the changing Arctic: A review and perspectives 

      Michel, Christine; Hamilton, J.; Hansen, Edmond; Barber, Dave; Reigstad, Marit; Iocozza, J; Seuthe, Lena; Niemi, Andrea (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-28)
      Over the past decade or so, international research efforts, many of which were part of the International Polar Year, have accrued our understanding of the Arctic outflow shelves. The Arctic outflow shelves, namely the East Greenland Shelf (EGS) and the Canadian Arctic Archipelago (CAA), serve as conduits through which Arctic sea ice and waters and their properties are exported to the North Atlantic. ...
    • Arctic sea ice algae differ markedly from phytoplankton in their ecophysiological characteristics 

      Kvernvik, Ane Cecilie; Hoppe, Clara Jule Marie; Greenacre, Michael; Verbiest, Sander; Wiktor, Józef Maria; Gabrielsen, Tove M.; Reigstad, Marit; Leu, Eva (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-20)
      Photophysiological and biochemical characteristics were investigated in natural communities of Arctic sea ice algae and phytoplankton to understand their respective responses towards variable irradiance and nutrient regimes. This study revealed large differences in photosynthetic efficiency and capacity between the 2 types of algal assemblages. Sea ice algal assemblages clearly displayed increased ...
    • An assessment of MOSJ - The state of the marine environment around Svalbard and Jan Mayen 

      Fauchald, Per; Arneberg, Per; Berge, Jørgen; Gerland, Sebastian; Kovacs, Kit M.; Reigstad, Marit; Sundet, Jan Henry (Research report; Forskningsrapport, 2014-05)
    • Asynchronous Accumulation of Organic Carbon and Nitrogen in the Atlantic Gateway to the Arctic Ocean 

      Paulsen, Maria Lund; Seuthe, Lena; Reigstad, Marit; Larsen, Aud; Cape, Matthias; Vernet, Maria (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-15)
      Nitrogen (N) is the main limiting nutrient for biological production in the Arctic Ocean. While dissolved inorganic N (DIN) is well studied, the substantial pool of N bound in organic matter (OM) and its bioavailability in the system is rarely considered. Covering a full annual cycle, we here follow N and carbon (C) content in particulate (P) and dissolved (D) OM within the Atlantic water inflow to ...
    • Carbon export in the seasonal sea ice zone north of Svalbard from winter to late summer 

      Dybwad, Christine; Assmy, Philipp; Olsen, Lasse Mork; Peeken, Ilka; Nikolopoulos, Anna; Krumpen, Thomas; Randelhoff, Achim; Tatarek, Agnieszka; Wiktor, Józef M.; Reigstad, Marit (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-21)
      Phytoplankton blooms in the Arctic Ocean's seasonal sea ice zone are expected to start earlier and occur further north with retreating and thinning sea ice cover. The current study is the first compilation of phytoplankton bloom development and fate in the seasonally variable sea ice zone north of Svalbard from winter to late summer, using short-term sediment trap deployments. Clear seasonal patterns ...
    • Continuous daylight in the high-Arctic summer supports high plankton respiration rates compared to those supported in the dark 

      Mesa, Elena; Delgado-Huertas, Antonio; Carillo-de-Albornoz, Paloma; Garcia-Corral, Lara S; Sanz-Martín, Marina; Wassmann, Paul; Reigstad, Marit; Sejr, Mikael; Dalsgaard, Tage; Duarte, Carlos M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-28)
      Plankton respiration rate is a major component of global CO2 production and is forecasted to increase rapidly in the Arctic with warming. Yet, existing assessments in the Arctic evaluated plankton respiration in the dark. Evidence that plankton respiration may be stimulated in the light is particularly relevant for the high Arctic where plankton communities experience continuous daylight in spring ...
    • Earlier sea-ice melt extends the oligotrophic summer period in the Barents Sea with low algal biomass and associated low vertical flux 

      Kohlbach, Doreen; Goraguer, Lucie; Bodur, Yasemin V.; Müller, Oliver; Amargant Arumí, Martí; Blix, Katalin; Bratbak, Gunnar; Chierici, Melissa; Dabrowska, Anna Maria; Dietrich, Ulrike; Edvardsen, Bente; Garcia, Laura; Gradinger, Rolf Rudolf; Hop, Haakon; Jones, Elizabeth Marie; Øyvind, Lundesgaard; Olsen, Lasse Mork; Reigstad, Marit; Saubrekka, Karoline; Tatarek, Agnieszka; Wiktor, Josef Maria; Wold, Anette; Assmy, Philipp (Journal article; Tidsskriftartikkel, 2023-03-27)
      The decrease in Arctic sea-ice extent and thickness as a result of global warming will impact the timing, duration, magnitude and composition of phytoplankton production with cascading effects on Arctic marine food-webs and biogeochemical cycles. Here, we elucidate the environmental drivers shaping the composition, abundance, biomass, trophic state and vertical flux of protists (unicellular eukaryotes), ...
    • Effects of mortality changes on biomass and production in Calanus spp. populations 

      Skardhamar, Jofrid; Reigstad, Marit; Carroll, Jolynn; Eiane, Ketil; Wexels Riser, Christian; Slagstad, Dag (Journal article; Tidsskriftartikkel; Peer reviewed, 2011-04-28)
      Calanus species are the main link between primary producers and higher trophic-level organisms in the Barents Sea. The natural mortality rate is an essential parameter for determining the standing stock of Calanus, but it is also one of the most uncertain parameters in present knowledge. The level of human activity, and the associated risk of pollution, is increasing in the Barents Sea, and knowledge ...
    • Episodic Arctic CO2 Limitation in the West Svalbard Shelf 

      Sanz-Martín, Marina; Chierici, Melissa; Mesa, Elena; Carrillo-de-Albornoz, Paloma; Delgado-Huertas, Antonio; Agusti, Susana; Reigstad, Marit; Kristiansen, Svein; Wassmann, Paul; Duarte, Carlos M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-06)
      The European Sector of the Arctic Ocean is characterized by low CO<sub>2</sub> concentrations in seawater during spring and summer, largely due to strong biological uptake driven by extensive plankton blooms in spring. The spring plankton bloom is eventually terminated by nutrient depletion and grazing. However, low CO<sub>2</sub> concentrations in seawater and low atmospheric resupply of CO<sub>2</sub> ...
    • 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 ...
    • Future Arctic Ocean Seasonal Ice Zones and Implications for Pelagic-Benthic Coupling 

      Wassmann, Paul; Reigstad, Marit (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      Despite concerns about rapid changes in Arctic Ocean physical forcing and ecosystem function, quantitative knowledge and time series are scarce. The number of reliable physical-biological coupled models and models based on remote sensing is small. To improve our comprehension of carbon flux in the most prominent Arctic Ocean feature, the seasonal ice zone, a possible first step is to evaluate how ...
    • 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, ...
    • Improving Chlorophyll-a Estimation from Sentinel-2 (MSI) in the Barents Sea using Machine Learning 

      Asim, Muhammad; Brekke, Camilla; Mahmood, Arif; Eltoft, Torbjørn; Reigstad, Marit (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-22)
      This article addresses methodologies for remote sensing of ocean Chlorophyll-a (Chl-a), with emphasis on the Barents Sea. We aim at improving the monitoring capacity by integrating in situ Chl-a observations and optical remote sensing to locally train machine learning (ML) models. For this purpose, in situ measurements of Chl-a ranging from 0.014–10.81 mg/m <sup>3</sup> , collected for the years ...
    • The Influence of Sea Ice Cover and Atlantic Water Advection on Annual Particle Export North of Svalbard 

      Dybwad, Christine Schumann; Lalande, Catherine; Bodur, Yasemin V.; Henley, Sean; Cottier, Finlo Robert; Ershova, Elizaveta; Hobbs, Laura; Last, Kim S.; Dabrowska, Anna Maria; Reigstad, Marit (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-04)
      The Arctic Ocean north of Svalbard has recently experienced large sea ice losses and the increasing prominence of Atlantic water (AW) advection. To investigate the impact of these ongoing changes on annual particle export, two moorings with sequential sediment traps were deployed in ice-free and seasonally ice-covered waters on the shelf north (NSv) and east (ESv) of Svalbard, collecting sinking ...
    • Interannual differences in sea ice regime in the north-western Barents Sea cause major changes in summer pelagic production and export mechanisms 

      Amargant I Arumi, Marti; Müller, Oliver; Bodur, Yasemin Vicdan; Ntinou, Iliana Vasiliki; Vonnahme, Tobias; Assmy, Philipp Kurt Wolf; Kohlbach, Doreen; Chierici, Melissa; Jones, Elizabeth Marie; Olsen, Lasse Mork; Tsagaraki, Tatiana; Reigstad, Marit; Bratbak, Gunnar; Gradinger, Rolf Rudolf (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-22)
      The Barents Sea is a highly dynamic and productive marine ecosystem and a hotspot of global warming. Variability in sea ice extent is a common feature in the Barents Sea with substantial movements of the sea ice edge on short-term, seasonal to interannual time scales. Historically the northern Barents Sea (north of 75◦N) has been ice-covered in winter, but recently it has become the area with most ...
    • New production regulates export stoichiometry in the ocean 

      Tamelander, Tobias; Reigstad, Marit; Olli, Kalle; Slagstad, Dag; Wassmann, Paul (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      The proportion in which carbon and growth-limiting nutrients are exported from the oceans’ productive surface layer to the deep sea is a crucial parameter in models of the biological carbon pump. Based on .400 vertical flux observations of particulate organic carbon (POC) and nitrogen (PON) from the European Arctic Ocean we show the common assumption of constant C:N stoichiometry not to be met. ...
    • Nutrients vs. turbulence, and the future of Arctic Ocean primary production 

      Randelhoff, Achim; Sundfjord, Arild; Fer, Ilker; Reigstad, Marit; Tremblay, Jean-Eric; Guthrie, John D. (Conference object; Konferansebidrag, 2016-11)
      This poster presents estimates of nitrate fluxes in the Arctic Ocean and speculates on the associated primary production in a future climate.
    • Potential drivers of sinking particle´s size spectra and vertical POC flux: Turbulence, phytoplankton and zooplankton 

      Wiedmann, Ingrid; Reigstad, Marit; Sundfjord, Arild; Basedow, Sünnje (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Relationship between carbon- and oxygen-based primary productivity in the Arctic Ocean, svalbard archipelago 

      Sanz-Martín, Marina; Vernet, Maria; Cape, Mattias R.; Cano, Elena M; Delgado-Huertas, Antonio; Reigstad, Marit; Wassmann, Paul; Duarte, Carlos M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-02)
      Phytoplankton contribute half of the primary production (PP) in the biosphere and are the major source of energy for the Arctic Ocean ecosystem. While PP measurements are therefore fundamental to our understanding of marine biogeochemical cycling, the extent to which current methods provide a definitive estimate of this process remains uncertain given differences in their underlying approaches, and ...
    • Responses in Arctic marine carbon cycle processes: Conceptual scenarios and implications for ecosystem function 

      Findlay, Helen S.; Gibson, Georgina; Kędra, Monika; Morata, Nathalie; Orchowska, Monika; Pavlov, Alexey K.; Reigstad, Marit; Silyakova, Anna; Tremblay, Jean-Éric; Walczowski, Waldemar; Weydmann, Agata; Logvinova, Christie (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-04-15)
      The Arctic Ocean is one of the fastest changing oceans, plays an important role in global carbon cycling and yet is a particularly challenging ocean to study. Hence, observations tend to be relatively sparse in both space and time. How the Arctic functions, geophysically, but also ecologically, can have significant consequences for the internal cycling of carbon, and subsequently influence carbon ...