Contrasting Life Traits of Sympatric Calanus glacialis and C. finmarchicus in a Warming Arctic Revealed by a Year-Round Study in Isfjorden, Svalbard

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Sea ice decline drives biogeographical shifts of key Calanus species in the central Arctic Ocean

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Sea ice decline drives biogeographical shifts of key Calanus species in the central Arctic Ocean

In recent decades, the central Arctic Ocean has been experiencing dramatic decline in sea ice coverage, thickness and extent, which is expected to have a tremendous impact on all levels of Arctic marine life. Here, we analyze the regional and temporal changes in pan-Arctic distribution and population structure of the key zooplankton species Calanus glacialis and C. hyperboreus in relation to recent changes in ice conditions, based on historical (1993–1998) and recent (2007–2016) zooplankton collections and satellite-based sea ice observations. We found strong correlations between Calanus abundance/population structure and a number of sea ice parameters. These relationships were particularly strong for C. glacialis, with higher numbers being observed at locations with a lower ice concentration, a shorter distance to the ice edge, and more days of open water. Interestingly, early stages of C. hyperboreus followed the same trends, suggesting that these two species substantially overlap in their core distribution area in the Arctic Ocean. Calanus glacialis and C. hyperboreus have been historically classified as shelf versus basin species, yet we conclude that both species can inhabit a wide range of bottom depths and their distribution in the Arctic Ocean is largely shaped by sea ice dynamics. Our data suggest that the core distribution patterns of these key zooplankton are shifting northwards with retreating sea ice and changing climate conditions.publishedVersio

Genetics redraws pelagic biogeography of Calanus

Planktonic copepods of the genus Calanus play a central role in North Atlantic/Arctic marine food webs. Here, using molecular markers, we redrew the distributional ranges of Calanus species inhabiting the North Atlantic and Arctic Oceans and revealed much wider and more broadly overlapping distributions than previously described. The Arctic shelf species, C. glacialis, dominated the zooplankton assemblage of many Norwegian fjords, where only C. finmarchicus has been reported previously. In these fjords, high occurrences of the Arctic species C. hyperboreus were also found. Molecular markers revealed that the most common method of species identification, prosome length, cannot reliably discriminate the species in Norwegian fjords. Differences in degree of genetic differentiation among fjord populations of the two species suggested that C. glacialis is a more permanent resident of the fjords than C. finmarchicus. We found no evidence of hybridization between the species. Our results indicate a critical need for the wider use of molecular markers to reliably identify and discriminate these morphologically similar copepod species, which serve as important indicators of climate responses.publishedVersionPaid Open Acces

Toward a global reference database of COI barcodes for marine zooplankton

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bucklin, A., Peijnenburg, K. T. C. A., Kosobokova, K. N., O'Brien, T. D., Blanco-Bercial, L., Cornils, A., Falkenhaug, T., Hopcroft, R. R., Hosia, A., Laakmann, S., Li, C., Martell, L., Questel, J. M., Wall-Palmer, D., Wang, M., Wiebe, P. H., & Weydmann-Zwolicka, A. Toward a global reference database of COI barcodes for marine zooplankton. Marine Biology, 168(6), (2021): 78, https://doi.org/10.1007/s00227-021-03887-y.Characterization of species diversity of zooplankton is key to understanding, assessing, and predicting the function and future of pelagic ecosystems throughout the global ocean. The marine zooplankton assemblage, including only metazoans, is highly diverse and taxonomically complex, with an estimated ~28,000 species of 41 major taxonomic groups. This review provides a comprehensive summary of DNA sequences for the barcode region of mitochondrial cytochrome oxidase I (COI) for identified specimens. The foundation of this summary is the MetaZooGene Barcode Atlas and Database (MZGdb), a new open-access data and metadata portal that is linked to NCBI GenBank and BOLD data repositories. The MZGdb provides enhanced quality control and tools for assembling COI reference sequence databases that are specific to selected taxonomic groups and/or ocean regions, with associated metadata (e.g., collection georeferencing, verification of species identification, molecular protocols), and tools for statistical analysis, mapping, and visualization. To date, over 150,000 COI sequences for ~ 5600 described species of marine metazoan plankton (including holo- and meroplankton) are available via the MZGdb portal. This review uses the MZGdb as a resource for summaries of COI barcode data and metadata for important taxonomic groups of marine zooplankton and selected regions, including the North Atlantic, Arctic, North Pacific, and Southern Oceans. The MZGdb is designed to provide a foundation for analysis of species diversity of marine zooplankton based on DNA barcoding and metabarcoding for assessment of marine ecosystems and rapid detection of the impacts of climate change.Funding sources for authors of the review paper are described here: Scientific Committee on Oceanic Research (SCOR), and a grant to SCOR from the U.S. National Science Foundation (OCE-1840868). Netherlands Organization for Scientific Research (NWO) Vidi Grant/Award Number: 016.161.351 to K.T.C.A.P. European Union Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 746186 (POSEIDoN) to D.W.P. The work of K.N.K. was performed in the framework of the state assignment of IO RAS (Theme No. 0128-2021-0007) and partially supported by Russian Foundation for Basic Research grants No. 18-05-60158 and No. 19-04-00955. The work of A.W.Z. was supported by a grant from HIDEA—Hidden diversity of the Arctic Ocean (No. 2017/27/B/NZ8/01056) from the National Science Centre, Poland, and a Fulbright Senior Award. The Norwegian Taxonomy Initiative of the Norwegian Biodiversity Information Centre provided funding for A.H. and L.M. (Project Nos. 70184233/HYPNO and 70184240/NORHYDRO), and for T.F. (Project Nos. 70184233/COPCLAD and 70184241/HYPCOP). The work of R.R.H. and J.M.Q. was supported by Census of Marine Life and NOAA Ocean Exploration and Research (NA05OAR4601079 and NA15OAR0110209). The work of S.L. was conducted at the Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB). HIFMB is a collaboration between the Alfred-Wegener-Institute, Helmholtz-Center for Polar and Marine Research, and the Carl-von-Ossietzky University Oldenburg, initially funded by the Ministry for Science and Culture of Lower Saxony and the Volkswagen Foundation through the Niedersächsisches Vorab’ grant program (Grant No. ZN3285)

Abundance of zooplankton during POLARSTERN cruise ARK-XIV/1a (PS51)

Zooplankton was collected by Birgit Stroscher (AWI) at three deep stations in the region of the Alpha Ridge in the Makarov Basin of the Arctic Ocean. Sampling was carried out between 15 and 18 July, 1998 during the cruise of RV "Polarstern" (ARK-XIV/1a). Nine depth strata from the bottom to the surface were sampled in a vertical manner with a multiple opening-closing net (Multinet Maxi, Hydrobios, Kiel, 0.49 m² mouth opening, 150 µm mesh). It was the first cruise when Multinet Maxi net model was used for zooplankton sampling in the ice-covered waters of the Arctic Ocean. Regular depth intervals were 0m-50-100-200-500-750-1000-1500-2000m-bottom. The zooplankton samples were preserved in 4% borax-buffered formalin. The samples were processed at Shirshov Institute of Oceanology, Russian Academy of Sciences (IORAS) by Dr. Ksenia Kosobokova. All zooplankton organisms from a sample were sorted to main taxonomical groups and for copepods further to species and stage level. Numerous small zooplankton organisms 3.1 mm, CV > 2.9 mm). Prosome length was measured from the tip of the cephalosome to the distal lateral end of the last thoracic segment. Earlier copepodite stages CI–CIV of Calanus belonged almost exclusively to C. glacialis and Calanus hyperboreus. They were separated by morphology and body size according to Hirche et al. (1994)

Cross-shelf structure and distribution of mesozooplankton communities in the East-Siberian Sea and the adjacent Arctic Ocean

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 community structure of mesozooplankton in the ESS and the adjacent Arctic Ocean based on recent (September 2009, 2015) as well as historical (August–September 1946, 1948) observations. We found that the overall biomass and abundance during our studies were significantly lower than in the adjacent Chukchi Sea, but higher than historical estimates from the ESS, around 25–35 mg DW m−3. The diversity was low and characteristic for other Arctic shelf seas, with increasing number of species in deeper waters. Biomass was highest at the shelf break, where it approached 70 mg DW m−3, and was mainly composed of the large copepod Calanus glacialis. On the shelf, abundance and biomass were low (10–20 mg DW m−3) and was dominated by small copepods and chaetognaths. Several distinct assemblages of zooplankton were identified and related to the physical properties of the water masses present. A striking result was the presence of both Atlantic and Pacific expatriates in offshore waters close to the shelf break, but generally not on the shelf itself. Tracking these advected organisms could be a useful tool in determining the pathways, extent, and transit time of Atlantic and Pacific water entering the Arctic

Zooplankton abundance and physical oceanography during POLARSTERN cruise ARK-IX/4 to the Laptev Sea and Arctic Ocean in 1993

This data collection contains surface temperature, salinity and ice coverage as well as zooplankton abundance measured on multinet samples during POLARSTERN cruise ARK-IX/4 to the Laptev Sea and Arctic Ocean in 1993

Abundance of zooplankton during POLARSTERN cruise ARK-XII/1 (PS41)

Abundances of zooplankton taxa were calculated in the Arctic Ocean during Polarstern cruise ARK-XII/1. Samples were taken with the Multinet midi (Hydrobios, Kiel), which is equipped with nine nets (mesh size: 150 µm)