• Flexible behaviour in a mesopelagic fish (Maurolicus muelleri) 

      Klevjer, Thor Aleksander; Røstad, Anders; Aksnes, Dag Lorents; Kaartvedt, Stein; Christiansen, Svenja (Journal article; Peer reviewed, 2021)
      Variability of mesopelagic scattering layers is often attributed to environmental conditions or multi-species layer composition. Yet, little is known about variation in behaviour among the individuals forming scattering ...
    • Herding mesopelagic fish by light 

      Kaartvedt, Stein; Røstad, Anders; Opdal, Anders Frugård; Aksnes, Dag Lorents (Peer reviewed; Journal article, 2019)
      To assess organisms forming mesopelagic scattering layers in the Red Sea, we took advantage of their reactions to light. We used a remotely operated vehicle (ROV) equipped with LED lamps for herding the acoustic targets ...
    • 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 ...
    • Impact of hatch-date on early life growth and survival of Mueller's pearlside (Maurolicus Muelleri) larvae, and life-history consequences 

      Folkvord, Arild; Gundersen, Geir; Albretsen, Jon; Asplin, Lars; Kaartvedt, Stein; Giske, Jarl (Peer reviewed; Journal article, 2016-02)
      Growth and survival of Maurolicus muelleri larvae in Herdlefjorden, Norway, were investigated by daily otolith increment analysis. While high egg densities were generally observed throughout the spawning season, three ...
    • Jellyfish distribute vertically according to irradiance 

      Bozman, Andrea; Titelman, Josefin; Kaartvedt, Stein; Eiane, Ketil; Aksnes, Dag Lorents (Peer reviewed; Journal article, 2017-03)
      We tested the hypothesis that the coronate jellyfish Periphylla periphylla distributes vertically according to a preferential range of absolute light intensities. The study was carried out in Lurefjorden, Norway, a fjord ...
    • Large mesopelagic fishes biomass and trophic efficiency in the open ocean 

      Irigoien, Xabier; Klevjer, Thor A.; Røstad, Anders; Martinez, U.; Boyra, G.; Acuna, J. L.; Bode, A.; Echevarria, F.; Gonzalez-Gordillo, J. I.; Hernández-León, Santiago; Augsti, S.; Aksnes, Dag Lorents; Duarte, C. M.; Kaartvedt, Stein (Peer reviewed; Journal article, 2014-02-07)
      With a current estimate of ~1,000 million tons, mesopelagic fishes likely dominate the world total fishes biomass. However, recent acoustic observations show that mesopelagic fishes biomass could be significantly larger ...
    • Light comfort zone in a mesopelagic fish emerges from adaptive behaviour along a latitudinal gradient 

      Langbehn, Tom; Aksnes, Dag Lorents; Kaartvedt, Stein; Fiksen, Øyvind; Jørgensen, Christian (Peer reviewed; Journal article, 2019)
      Throughout the oceans, small fish and other micronekton migrate between daytime depths of several hundred meters and near-surface waters at night. These diel vertical migrations of mesopelagic organisms structure pelagic ...
    • Light comfort zones of mesopelagic acoustic scattering layers in two contrasting optical environments 

      Røstad, Anders; Kaartvedt, Stein; Aksnes, Dag Lorents (Peer reviewed; Journal article, 2016-07)
      We make a comparison of the mesopelagic sound scattering layers (SLs) in two contrasting optical environments; the clear Red Sea and in murkier coastal waters of Norway (Masfjorden). The depth distributions of the SL in ...
    • Light penetration structures the deep acoustic scattering layers in the global ocean 

      Aksnes, Dag Lorents; Røstad, Anders; Kaartvedt, Stein; Martinez, Udane; Duarte, Carlos M.; Irigoien, Xabier (Peer reviewed; Journal article, 2017)
      The deep scattering layer (DSL) is a ubiquitous acoustic signature found across all oceans and arguably the dominant feature structuring the pelagic open ocean ecosystem. It is formed by mesopelagic fishes and pelagic ...
    • Mesoscale Eddies Are Oases for Higher Trophic Marine Life 

      Godø, Olav Rune; Samuelsen, Annette; Macaulay, Gavin J.; Patel, Ruben; Hjøllo, Solfrid Sætre; Horne, John; Kaartvedt, Stein; Johannessen, Johnny A. (Peer reviewed; Journal article, 2012-01-17)
      Mesoscale eddies stimulate biological production in the ocean, but knowledge of energy transfers to higher trophic levels within eddies remains fragmented and not quantified. Increasing the knowledge base is constrained ...
    • Pushing the limits of photoreception in twilight conditions: The rod-like cone retina of the deep-sea pearlsides 

      Busserolles de, Fanny; Cortesi, Fabio; Helvik, Jon Vidar; Davies, Wayne I. L.; Templin, Rachel M.; Sullivan, Robert K. P.; Michell, Craig T.; Mountford, Jessica K.; Collin, Shaun P.; Irigoien, Xabier; Kaartvedt, Stein; Marshall, Justin (Peer reviewed; Journal article, 2017)
      Most vertebrates have a duplex retina comprising two photoreceptor types, rods for dim-light (scotopic) vision and cones for bright-light (photopic) and color vision. However, deep-sea fishes are only active in dim-light ...
    • Vertical distribution and trophic interactions of zooplankton and fish in Masfjorden, Norway 

      Giske, Jarl; Aksnes, Dag Lorents; Balino, Beatriz M.; Kaartvedt, Stein; Lie, Ulf; Nordeide, Jarle Tryti; Salvanes, Anne Gro Vea; Wakili, Sami M.; Aadnesen, Agnes (Peer reviewed; Journal article, 1990)
      The distribution, biomass, and predator-prey relationships of the pelagic assemblage in Masfjorden, western Norway, was studied in January 1989. The pelagic biomass was dominated by particulate organic matter. Biomasses ...