• Eat or sleep: Availability of winter prey explains mid-winter and spring activity in an Arctic Calanus population 

      Hobbs, Laura; Banas, Neil S.; Cottier, Finlo Robert; Berge, Jørgen; Daase, Malin (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-25)
      Copepods of the genus <i>Calanus</i> have adapted to high levels of seasonality in prey availability by entering a period of hibernation during winter known as diapause, but repeated observations of active <i>Calanus</i> spp. have been made in January in high latitude fjords which suggests plasticity in over-wintering strategies. During the last decade, the period of Polar Night has been studied ...
    • From polar night to midnight sun: Diel vertical migration, metabolism and biogeochemical role of zooplankton in a high Arctic fjord (Kongsfjorden, Svalbard) 

      Darnis, Gérald; Hobbs, Laura; Geoffroy, Maxime; Grenvald, Julie Cornelius; Renaud, Paul; Berge, Jørgen; Cottier, Finlo Robert; Kristiansen, Svein; Daase, Malin; Søreide, Janne; Wold, Anette; Morata, Nathalie; Gabrielsen, Tove M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-24)
      Zooplankton vertical migration enhances the efficiency of the ocean biological pump by translocating carbon (C) and nitrogen (N) below the mixed layer through respiration and excretion at depth. We measured C and N active transport due to diel vertical migration (DVM) in a Svalbard fjord at 79°N. Multifrequency analysis of backscatter data from an Acoustic Zooplankton Fish Profiler moored from January ...
    • 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 ...
    • A marine zooplankton community vertically structured by light across diel to interannual timescales 

      Hobbs, Laura; Banas, Neil S.; Cohen, Jonathan H.; Cottier, Finlo Robert; Berge, Jørgen; Varpe, Øystein (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-24)
      The predation risk of many aquatic taxa is dominated by visually searching predators, commonly a function of ambient light. Several studies propose that changes in visual predation will become a major climate-change impact on polar marine ecosystems. The High Arctic experiences extreme seasonality in the light environment, from 24 h light to 24 h darkness, and therefore provides a natural laboratory ...
    • Moonlight Drives Ocean-Scale Mass Vertical Migration of Zooplankton during the Arctic Winter 

      Last, Kim; Hobbs, Laura; Berge, Jørgen; Brierley, Andrew S; Cottier, Finlo Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-07)
      In extreme high-latitude marine environments that are without solar illumination in winter, light-mediated patterns of biological migration have historically been considered non-existent [1]. However, diel vertical migration (DVM) of zooplankton has been shown to occur even during the darkest part of the polar night, when illumination levels are exceptionally low [2, 3]. This paradox is, as ...
    • Nitrate supply and uptake in the Atlantic Arctic sea ice zone: seasonal cycle, mechanisms and drivers 

      Henley, Sian F.; Porter, Marie; Hobbs, Laura; Braun, Judith; Guillaume-Castel, Robin; Venables, Emily J.; Dumont, Estelle; Cottier, Finlo Robert (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-31)
      Nutrient supply to the surface ocean is a key factor regulating primary production in the Arctic Ocean under current conditions and with ongoing warming and sea ice losses. Here we present seasonal nitrate concentration and hydrographic data from two oceanographic moorings on the northern Barents shelf between autumn 2017 and summer 2018. The eastern mooring was sea ice-covered to varying degrees ...
    • Photoperiodism and overwintering in boreal and sub-Arctic Calanus finmarchicus populations 

      Coguiec, Estelle; Last, Kim S.; Cohen, Jonathan H.; Hobbs, Laura; Choquet, Marvin; Ershova, Elizaveta; Berge, Jørgen; Daase, Malin (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-08)
      The copepod Calanus finmarchicus, a key species in the North Atlantic, generally spends the non-productive season by descending into deep waters and entering diapause, a physiological state characterized by reduced metabolism and arrested development. In the open ocean, overwintering depths are below 600 m, where temperature and light conditions are favourable to initiate diapause. However, C. ...
    • Photophysiological cycles in Arctic krill are entrained by weak midday twilight during the Polar Night 

      Cohen, Jonathan H.; Last, Kim; Charpentier, Corie L.; Cottier, Finlo; Daase, Malin; Hobbs, Laura; Johnsen, Geir; Berge, Jørgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-19)
      Light plays a fundamental role in the ecology of organisms in nearly all habitats on Earth and is central for processes such as vision and the entrainment of the circadian clock. The poles represent extreme light regimes with an annual light cycle including periods of Midnight Sun and Polar Night. The Arctic Ocean extends to the North Pole, and marine light extremes reach their maximum extent in ...