• Borealization of the Arctic Ocean in response to anomalous advection from sub-Arctic seas. 

      Polyakov, Igor V.; Alkire, Mattew; Bluhm, Bodil; Brown, Kristina; Carmack, Eddy C.; Chierici, Melissa; Danielson, Seth L.; Ellingsen, Ingrid H.; Ershova, Elizaveta; Gardfeldt, Katrin; Ingvaldsen, Randi Brunvær; Pnyushkov, Andrey V.; Slagstad, Dag; Wassmann, Paul (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-03)
      An important yet still not well documented aspect of recent changes in the Arctic Ocean is associated with the advection of anomalous sub-Arctic Atlantic- and Pacific-origin waters and biota into the polar basins, a process which we refer to as borealization. Using a 37-year archive of observations (1981–2017) we demonstrate dramatically contrasting regional responses to atlantification (that part ...
    • Cross-shelf structure and distribution of mesozooplankton communities in the East-Siberian Sea and the adjacent Arctic Ocean 

      Ershova, Elizaveta; Kosobokova, Ksenia N. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-29)
      The East-Siberian Sea (ESS) plays a significant role in circulation of surface water and biological production in the Arctic, yet due to its remote location and historically difficult sampling conditions remains the most understudied of all Arctic shelf seas, with even baseline information on biological communities absent in literature. We aim to fill this gap by describing the distribution and ...
    • Diversity and Distribution of Meroplanktonic Larvae in the Pacific Arctic and Connectivity With Adult Benthic Invertebrate Communities 

      Ershova, Elizaveta; Descôteaux, Raphaëlle; Wangensteen, Owen; Iken, Katrin; Hopcroft, Russ; Smoot, Caitlin; Grebmeier, Jacqueline M.; Bluhm, Bodil (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-13)
      Pelagic larval stages (meroplankton) of benthic invertebrates seasonally make up a significant proportion of planktonic communities, as well as determine the distribution of their benthic adult stages, yet are frequently overlooked by both plankton and benthic studies. Within the Arctic, the role of meroplanktonic larvae may be particularly important in regions of inflow from sub-Arctic regions, ...
    • Evidence for oscillating circadian clock genes in the copepod Calanus finmarchicus during the summer solstice in the high Arctic 

      Hüppe, Lukas; Payton, Laura; Last, Kim; Wilcockson, David; Ershova, Elizaveta; Meyer, Bettina (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-15)
      The circadian clock provides a mechanism for anticipating environmental cycles and is synchronized by temporal cues such as daily light/dark cycle or photoperiod. However, the Arctic environment is characterized by several months of Midnight Sun when the sun is continuously above the horizon and where sea ice further attenuates photoperiod. To test if the oscillations of circadian clock genes remain ...
    • 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 ...
    • Meroplankton Diversity, Seasonality and Life-History Traits Across the Barents Sea Polar Front Revealed by High-Throughput DNA Barcoding 

      Descôteaux, Raphaëlle; Ershova, Elizaveta; Wangensteen, Owen S.; Præbel, Kim; Renaud, Paul Eric; Cottier, Finlo Robert; Bluhm, Bodil (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-28)
      In many species of marine benthic invertebrates, a planktonic larval phase plays a critical role in dispersal. Very little is known about the larval biology of most species, however, in part because species identification has historically been hindered by the microscopic size and morphological similarity among related taxa. This study aimed to determine the taxonomic composition and seasonal ...
    • Metabarcoding as a quantitative tool for estimating biodiversity and relative biomass of marine zooplankton 

      Ershova, Elizaveta; Wangensteen, Owen S.; Descoteaux, Raphaelle; Barth-Jensen, Coralie Marie Christine; Præbel, Kim (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-31)
      Although metabarcoding is a well-established tool for describing diversity of pelagic communities, its quantitative value is still controversial, with poor correlations previously reported between organism abundance/biomass and sequence reads. In this study, we explored an enhanced quantitative approach by metabarcoding whole zooplankton communities using a highly degenerate primer set for the ...
    • Origin of marine invertebrate larvae on an Arctic inflow shelf 

      Descoteaux, Raphaelle; Huserbråten, Mats Brockstedt Olsen; Jørgensen, Lis Lindal; Renaud, Paul Eric; Ingvaldsen, Randi Brunvær; Ershova, Elizaveta; Bluhm, Bodil (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-20)
      Many benthic invertebrate taxa possess planktonic early life stages which drift with water currents and contribute to dispersal of the species, sometimes reaching areas beyond the current ranges of the adults. Until recently, it had been difficult to identify planktonic larvae to species level due to lack of distinguishing features, preventing detection of expatriate species. Here, we used DNA ...
    • 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. ...
    • The relationship between patterns of benthic fauna and zooplankton in the Chukchi Sea and physical forcing 

      Pisareva, Maria; Pickart, Robert S.; Iken, Katrin; Ershova, Elizaveta; Grebmeier, Jacqueline M.; Cooper, Lee W.; Bluhm, Bodil; Nobre, Carolina; Hopcroft, Russell R.; Hu, Haoguo; Wang, Jia; Ashjian, Carin; Kosobokova, Ksenia N.; Whitledge, Terry (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-09)
      Using data from a number of summer surveys of the Chukchi Sea over the past decade, we investigate aspects in which the benthic fauna, sediment structure, and zooplankton there are related to circulation patterns and shelf hydrographic conditions. A flow speed map is constructed that reveals the major pathways on the shelf. Regions of enhanced flow speed are dictated by lateral constrictions—i ...
    • Seasonal Variability in the Zooplankton Community Structure in a Sub-Arctic Fjord as Revealed by Morphological and Molecular Approaches 

      Coguiec, Estelle; Ershova, Elizaveta; Daase, Malin; Vonnahme, Tobias R.; Wangensteen, Owen S.; Gradinger, Rolf; Præbel, Kim; Berge, Jørgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-04)
      Phyto- and zooplankton in Arctic and sub-Arctic seas show very strong seasonal changes in diversity and biomass. Here we document the seasonal variability in the mesozooplankton community structure in a sub-Arctic fjord in Northern Norway based on monthly sampling between November 2018 and February 2020. We combined traditional morphological zooplankton identification with DNA metabarcoding of a 313 ...
    • What feeds the benthos in the Arctic basins? Assembling a carbon budget for the deep Arctic ocean 

      Wiedmann, Ingrid; Ershova, Elizaveta; Bluhm, Bodil; Nöthig, Eva-Maria; Kosobokova, Ksenia; Boetius, Antje; Gradinger, Rolf R. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-16)
      Half of the Arctic Ocean is deep sea (>1000 m), and this area is currently transitioning from being permanently ice-covered to being seasonally ice-free. Despite these drastic changes, it remains unclear how organisms are distributed in the deep Arctic basins, and particularly what feeds them. Here, we summarize data on auto- and heterotrophic organisms in the benthic, pelagic, and sympagic realm ...
    • Widely rhythmic transcriptome in Calanus finmarchicus during the high Arctic summer solstice period 

      Payton, Laura; Hüppe, Lukas; Noirot, Celine; Hoede, Claire; Last, Kim; Wilcockson, David; Ershova, Elizaveta; Valière, Sophie; Meyer, Bettina (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-10)
      Solar light/dark cycles and seasonal photoperiods underpin daily and annual rhythms of life on Earth. Yet, the Arctic is characterized by several months of permanent illumination (“midnight sun”). To determine the persistence of 24h rhythms during the midnight sun, we investigated transcriptomic dynamics in the copepod <i>Calanus finmarchicus</i> during the summer solstice period in the Arctic, with ...