• 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 (Peer reviewed; Journal article, 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 ...
    • Bacterial community composition responds to changes in copepod abundance and alters ecosystem function in an Arctic mesocosm study 

      Tsagaraki, Tatiana Margo; Pree, Bernadette; Leiknes, Øystein; Larsen, Aud; Bratbak, Gunnar; Øvreås, Lise; Egge, Jorun Karin; Spanek, Roman; Paulsen, Maria Lund; Olsen, Yngvar; Vadstein, Olav; Thingstad, T. Frede (Peer reviewed; Journal article, 2018)
      Combining a minimum food web model with Arctic microbial community dynamics, we have suggested that top-down control by copepods can affect the food web down to bacterial consumption of organic carbon. Pursuing this ...
    • Bacterial Response to Permafrost Derived Organic Matter Input in an Arctic Fjord 

      Müller, Oliver; Seuthe, Lena; Bratbak, Gunnar; Paulsen, Maria Lund (Peer reviewed; Journal article, 2018-08-06)
      The warming of the Arctic causes increased riverine discharge, coastal erosion, and the thawing of permafrost. Together, this is leading to an increased wash out of terrestrial dissolved organic matter (tDOM) into the ...
    • Biological transformation of Arctic dissolved organic matter in a NE Greenland fjord 

      Paulsen, Maria Lund; Müller, Oliver; Larsen, Aud; Møller, Eva Friis; Middelboe, Mathias; Sejr, Mikael Kristian; Stedmon, Colin A. (Peer reviewed; Journal article, 2018-12-07)
      Arctic waters are often enriched with terrestrial dissolved organic matter (DOM) characterized by having elevated visible wavelength fluorescence (commonly termed humic-like). Here, we have identified the sources of ...
    • Carbon Bioavailability in a High Arctic Fjord Influenced by Glacial Meltwater, NE Greenland 

      Paulsen, Maria Lund; Nielsen, Sophia Elisabeth Bardram; Müller, Oliver; Møller, Eva Friis; Stedmon, Colin A.; Juul-Pedersen, Thomas; Markager, Stiig; Sejr, Mikael Kristian; Delgado Huertas, Antonio; Larsen, Aud; Middelboe, Mathias (Peer reviewed; Journal article, 2017-06-08)
      The land-to-ocean flux of organic carbon is increasing in glacierized regions in response to increasing temperatures in the Arctic (Hood et al., 2015). In order to understand the response of the coastal ecosystem metabolism ...
    • 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 (Peer reviewed; Journal article, 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 ...
    • Heterogeneous distribution of plankton within the mixed layer and its implications for bloom formation in tropical seas 

      Calbet, Albert; Agersted, Mette Dalgaard; Kaartvedt, Stein; Møhl, Malene; Møller, Eva Friis; Enghoff-Poulsen, Søren; Paulsen, Maria Lund; Solberg, Ingrid; Tang, Kam W.; Tönnesson, Kajsa; Raitsos, Dionysios E.; Nielsen, Torkel Gissel (Peer reviewed; Journal article, 2015-06-11)
      Intensive sampling at the coastal waters of the central Red Sea during a period of thermal stratification, prior to the main seasonal bloom during winter, showed that vertical patches of prokaryotes and microplankton ...
    • Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic spring bloom development 

      Paulsen, Maria Lund; Riisgård, Karen; St. John, Mike; Thingstad, T. Frede; Nielsen, Torkel Gissel (Peer reviewed; Journal article, 2017)
      The subarctic Atlantic phytoplankton spring bloom is one of the largest biological features of the ocean; however, processes initiating the bloom are still not well understood. We hypothesize that the microbial grazing ...
    • Microbial dynamics in high latitude ecosystems. Responses to mixing, runoff and seasonal variation a rapidly changing environment 

      Paulsen, Maria Lund (Doctoral thesis, 2017-11-08)
      The pronounced warming at high latitude alters a range of physical conditions i.e. the magnitude of runoff, sea-ice extent and strength of stratification and thus affect the biological systems. As microorganisms form the ...
    • Phytoplankton dynamics in contrasting early stage North Atlantic spring blooms: composition, succession, and potential drivers 

      Daniels, Chris; Poulton, Alex J.; Mario, Esposito; Paulsen, Maria Lund; Bellerby, Richard; St. John, Mike; Martin, Adrian P. (Peer reviewed; Journal article, 2015-04-24)
      The spring bloom is a key annual event in the phenology of pelagic ecosystems, making a major contribution to the oceanic biological carbon pump through the production and export of organic carbon. However, there is little ...
    • Pre-bloom dynamics of the Subpolar North Atlantic microbial food web 

      Paulsen, Maria Lund (Master thesis, 2013-02-18)
      The aim of this study was to investigate the microbial planktonic food web in the pre- bloom period of the Subpolar North Atlantic Ocean. Through repeated visits to the Icelandic Basin, Norwegian Basin, and on the Shetland ...
    • A simple adjustment to test reliability of bacterivory rates derived from the dilution method 

      Pree, Bernadette; Kuhlisch, Constanze; Pohnert, Georg; Sazhin, Andrey; Jakobsen, Hans Henrik; Paulsen, Maria Lund; Frischer, Marc E.; Stoecker, Diane K.; Nejstgaard, Jens C.; Larsen, Aud (Peer reviewed; Journal article, 2016-02)
      Quantification of grazing losses of marine heterotrophic bacteria is critical for understanding nutrient and carbon pathways in aquatic systems. The dilution method is a commonly used experimental approach for quantifying ...
    • Simple models combining competition, defence and resource availability have broad implications in pelagic microbial food webs 

      Våge, Selina; Bratbak, Gunnar; Egge, Jorun Karin; Heldal, Mikal; Larsen, Aud; Norland, Svein; Paulsen, Maria Lund; Pree, Bernadette; Sandaa, Ruth-Anne; Skjoldal, Evy Foss; Tsagaraki, Tatiana Margo; Øvreås, Lise; Thingstad, T. Frede (Peer reviewed; Journal article, 2018-09)
      In food webs, interactions between competition and defence control the partitioning of limiting resources. As a result, simple models of these interactions contain links between biogeochemistry, diversity, food web structure ...
    • Spatiotemporal Dynamics of Ammonia-Oxidizing Thaumarchaeota in Distinct Arctic Water Masses 

      Müller, Oliver; Wilson, Bryan; Paulsen, Maria Lund; Rumińska, Agnieszka; Armo, Hilde R.; Bratbak, Gunnar; Øverås, Lise (Peer reviewed; Journal article, 2018-01-23)
      One of the most abundant archaeal groups on Earth is the Thaumarchaeota. They are recognized as major contributors to marine ammonia oxidation, a crucial step in the biogeochemical cycling of nitrogen. Their universal ...
    • Synechococcus in the Atlantic Gateway to the Arctic Ocean 

      Paulsen, Maria Lund; Doré, Hugo; Garczarek, Laurence; Seuthe, Lena; Müller, Oliver; Sandaa, Ruth-Anne; Bratbak, Gunnar; Larsen, Aud (Peer reviewed; Journal article, 2016-10-05)
      Increasing temperatures, with pronounced effects at high latitudes, have raised questions about potential changes in species composition, as well as possible increased importance of small-celled phytoplankton in marine ...
    • Winter−spring transition in the subarcticAtlantic: microbial response to deep mixingand pre-bloom production 

      Paulsen, Maria Lund; Riisgaard, Karen; Frede, Thingstad; St. John, Mike; Nielsen, Torkel Gissel (Peer reviewed; Journal article, 2015-09-23)
      In temperate, subpolar and polar marine systems, the classical perception is that diatoms initiate the spring bloom and thereby mark the beginning of the productive season. Contrary to this view, we document an active ...