title: Strong Seasonality of Marine Microbial Eukaryotes in a High-Arctic Fjord (Isfjorden, in West Spitsbergen, Norway).
abstract: The Adventfjorden time series station (IsA) in Isfjorden, West Spitsbergen, Norway, was sampled frequently from December 2011 to December 2012. The community composition of microbial eukaryotes (size, 0.45 to 10 μm) from a depth of 25 m was determined using 454 sequencing of the 18S V4 region amplified from both DNA and RNA. The compositional changes throughout the year were assessed in relation to in situ fjord environmental conditions. Size fractionation analyses of chlorophyll a showed that the photosynthetic biomass was dominated by small cells (<10 μm) most of the year but that larger cells dominated during the spring and summer. The winter and early-spring communities were more diverse than the spring and summer/autumn communities. Dinophyceae were predominant throughout the year. The Arctic Micromonas ecotype was abundant mostly in the early-bloom and fall periods, whereas heterotrophs, such as marine stramenopiles (MASTs), Picozoa, and the parasitoid marine alveolates (MALVs), displayed higher relative abundance in the winter than in other seasons. Our results emphasize the extreme seasonality of Arctic microbial eukaryotic communities driven by the light regime and nutrient availability but point to the necessity of a thorough knowledge of hydrography for full understanding of their succession and variability.
authors.affiliation: Department of Arctic Biology, The University Centre in Svalbard (UNIS), Longyearbyen, Norway tove.gabrielsen@unis.no miriam.marquardt@unis.no.|Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, Tromsø, Norway.
authors.forename: Miriam
authors.initials: M
authors.lastname: Marquardt
authors.affiliation: Department of Arctic Biology, The University Centre in Svalbard (UNIS), Longyearbyen, Norway.
authors.forename: Anna
authors.initials: A
authors.lastname: Vader
authors.affiliation: Department of Arctic Biology, The University Centre in Svalbard (UNIS), Longyearbyen, Norway.|Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, Tromsø, Norway.
authors.forename: Eike I
authors.initials: EI
authors.lastname: Stübner
authors.affiliation: Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, Tromsø, Norway.
authors.forename: Marit
authors.initials: M
authors.lastname: Reigstad
authors.affiliation: Department of Arctic Biology, The University Centre in Svalbard (UNIS), Longyearbyen, Norway tove.gabrielsen@unis.no miriam.marquardt@unis.no.
authors.forename: Tove M
authors.initials: TM
authors.lastname: Gabrielsen
mesh_terms: D059001:Aquatic Organisms / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D001110:Arctic Regions; D058448:Biota; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D063366:Estuaries; D056890:Eukaryota / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D056186:Metagenomics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012621:Seasons; D017422:Sequence Analysis, DNA; D013538:Svalbard
chemical_list: D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S