The pan-Arctic biodiversity of marine pelagic and sea-ice unicellular eukaryotes: a first-attempt assessment

Abstract

Arctic marine unicellular eukaryotes are composed of microalgae and non-autotrophic protists. These eukaryotes comprise a well-diversified group of organisms that are either adapted to live in the upper water column of coastal and oceanic regions, here defined as phytoplankton/ pelagic communities, or in bottom horizons of sea ice and known as sympagic/sea-ice-associated communities. There are approximately 5,000 recognized legitimate marine phytoplankton species and an unknown number of sympagic eukaryotes. Although pelagic and sea-ice eukaryotes have been described since the exploration phase of the Arctic regions up to the early twentieth century, no synthesis regarding information from all Arctic seas have been undertaken, and no exhaustive current information provides the exact number and composition of species on a pan-Arctic scale. In a first attempt to assess the pan-Arctic diversity of pelagic and sea-ice eukaryotes, a wealth of data from various sources (e.g., scientific publications, unpublished reports, databases) were reviewed, while taxonomic data were confirmed with current nomenclature and classification. We report a total of 2,106 marine singlecelled eukaryote taxa with 1,874 phytoplankton and 1,027 sympagic taxa from four grouped pan-Arctic regions, namely Alaska, Canada, Scandinavia including Greenland and the Russian Federation. Both phytoplankton and sympagic taxa were present in four of the six supergroups of eukaryotes described by Adl et al. (J Eukaryot Microbiol 52:399-451, 2005), which are Archaeplastida (chlorophytes and prasinophytes), Chromalveolata (e.g., chrysophytes, cryptophytes, diatoms, dictyochophytes, dinoflagellates and prymnesiophytes), Excavata (euglenids) and Opisthokonta (choanoflagellates). The bulk of this marine biodiversity of Arctic microorganisms consists of large cells (>20 μm) mainly due to examination at low magnification under light microscopy. Future efforts should focus enhancing our knowledge of the biological diversity of small cells (<20 μm), which represent less than 20% of our actual biodiversity assessment of pan-Arctic regions.

Growth and bioactive secondary metabolites of arctic Protoceratium reticulatum (Dinophyceae)

“…Several studies have reported the presence of either Protoceratium reticulatum or YTX in mussels in the Arctic Ocean (Okolodkov, 2005;Vershinin et al, 2006;Poulin et al, 2011). The Greenland isolates of P. reticulatum, as verified by detailed morphologic and phylogenetic analysis, are the first isolates grown in culture of this species from arctic waters.…”

“…Thus, range extension of phytoplankton taxa responsible for HABs and toxin production into and within the Arctic are to be expected. In the past, a number of harmful eukaryotes have been recorded in marine plankton and sympagic communities across the entire Arctic region, with the domoic acid producing planktonic diatoms Pseudo-nitzschia delicatissima, Pseudo-nitzschia pungens and Pseudo-nitzschia seriata, the prymnesiophyte Phaeocystis pouchetii, and the dinoflagellates Azadinium sp., Amphidoma languida, Alexandrium tamarense, Alexandrium ostenfeldii, Dinophysis acuminata, Dinophysis acuta, Dinophysis norvegica, Gonyaulax spinifera, and Protoceratium reticulatum as the most abundant species (Okolodkov, 2005;Poulin et al, 2011;Tillmann et al, 2014).…”

Role of sea ice in global biogeochemical cycles: emerging views and challenges

“…Sea ice provides a vast habitat for productive microbial communities consisting of algae, bacteria, archea, heterotrophic protists, funghi as well as viruses [Horner et al 1992;Deming et al, 2010;Thomas and Dieckmann, 2010;Poulin et al, 2011]. Distinct communities are found at the base, in the interior and at the surface of ice floes [see, Horner, 1985;Arrigo et al, 2010].…”

Primary producers and production in Hornsund and Kongsfjorden – comparison of two fjord systems

“…-Arctic planktonic protists account for over 2106 species (Poulin et al 2011). Hop et al (2006) reported a total of 148 taxa, of which Bacillariophyta (45%) and Dinophyta (11%) were the dominant groups in Kongsfjorden (Table 3).…”

“…This community develops through three distinct phases in the transition from winter to spring, which is described by Leu et al (2015). A total of 1027 sympagic protist taxa have been reported from four PanArctic regions (Syvertsen 1991;Poulin et al 2011). The biomass of ice algae communities is almost exclusively dominated by the genera Nitzschia, Navicula, Pauliella and Fragilariopsis (Gosselin et al 1997;Riedel et al 2008;Leu et al 2015), which often account for >90% of the total algal cell abundance (Smith and Sakshaug 1990; von Quillfeldt 2000; Różańska et al 2009;Wiktor 2015).…”