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  • Norwegian Polar Institute  (2)
  • TAYLOR & FRANCIS AS  (1)
  • 1
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    Summertime plankton ecology in Fram Strait - a compilation of long- and short-term observations (2015)
    Norwegian Polar Institute
    In:  Polar Research, 34 (23349).
    Details
    Publication Date: 2019-07-10
    Description: Between Greenland and Spitsbergen, Fram Strait is a region where cold ice-covered Polar Water exits the Arctic Ocean with the East Greenland Current (EGC) and warm Atlantic Water enters the Arctic Ocean with the West Spitsbergen Current (WSC). In this compilation, we present two different data sets from plankton ecological observations in Fram Strait: (1) long-term measurements of satellite-derived (1998–2012) and in situ chlorophyll a (chl a) measurements (mainly summer cruises, 1991–2012) plus protist compositions (a station in WSC, eight summer cruises, 1998–2011); and (2) short-term measurements of a multidisciplinary approach that includes traditional plankton investigations, remote sensing, zooplankton, microbiological and molecular studies, and biogeochemical analyses carried out during two expeditions in June/July in the years 2010 and 2011. Both summer satellite-derived and in situ chl a concentrations showed slight trends towards higher values in the WSC since 1998 and 1991, respectively. In contrast, no trends were visible in the EGC. The protist composition in the WSC showed differences for the summer months: a dominance of diatoms was replaced by a dominance of Phaeocystis pouchetii and other small pico- and nanoplankton species. The observed differences in eastern Fram Strait were partially due to a warm anomaly in the WSC. Although changes associated with warmer water temperatures were observed, further long-term investigations are needed to distinguish between natural variability and climate change in Fram Strait. Results of two summer studies in 2010 and 2011 revealed the variability in plankton ecology in Fram Strait.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.3402/polar.v34.23349
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Insight into protist diversity in Arctic sea ice and melt-pond aggregate obtained by pyrosequencing (2014)
    Norwegian Polar Institute
    In:  Polar Research, 33 (23466).
    Details
    Publication Date: 2016-01-07
    Description: Protists in the central Arctic Ocean are adapted to the harsh environmental conditions of its various habitats. During the Polarstern cruise ARK-XXVI/3 in 2011, at one sea-ice station, large aggregates accumulated at the bottom of the melt ponds. In this study, the protist assemblages of the bottom layer of the sea-ice and melt-pond aggregate were investigated using flow cytometry and 454-pyrosequencing. The objective is to provide a first molecular overview of protist biodiversity in these habitats and to consider the overlaps and/or differences in the community compositions. Results of flow cytometry pointed to a cell size distribution that was dominated by 3–10 µm nanoflagellates. The phylogenetic classification of all sequences was conducted at a high taxonomic level, while a selection of abundant (≥1% of total reads) sequences was further classified at a lower level. At a high taxonomic level, both habitats showed very similar community structures, dominated by chrysophytes and chlorophytes. At a lower taxonomic level, dissimilarities in the diversity of both groups were encountered in the abundant biosphere. While sea-ice chlorophytes and chrysophytes were dominated by Chlamydomonas/Chloromonas spp. and Ochromonas spp., the melt-pond aggregate was dominated by Carteria sp., Ochromonas spp. and Dinobryon faculiferum. We suppose that the similarities in richness and community structure are a consequence of melt-pond freshwater seeping through porous sea ice in late summer. Differences in the abundant biosphere nevertheless indicate that environmental conditions in both habitats vary enough to select for different dominant species.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.3402/polar.v33.23466
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Evaluating the potential of 18S rDNA clone libraries to complement pyrosequencing data of marine protists with near full-length sequence information (2014)
    TAYLOR & FRANCIS AS
    In:  EPIC3Marine Biology Research, TAYLOR & FRANCIS AS, 10(8), pp. 771-780, ISSN: 1745-1000
    Details
    Publication Date: 2019-07-17
    Description: Sequencing of 18S rDNA clone libraries and 454-pyrosequencing are valuable methods used to describe microbial diversity. The massively parallel 454-pyrosequencing generates vast amounts of ribosomal sequence data and has the potential to uncover more organisms, even rare species. However, the relatively short sequence lengths of ~500 bp are suboptimal for taxonomic annotation and phylogenetic analyses. In this study, we assessed the potential of 18S ribosomal clone libraries to complement corresponding 454-pyrosequencing data with near full-length sequence information. This involved a comparison of protist community compositions in five polar samples suggested by 18S rDNA clone libraries with the corresponding community compositions suggested by 454-pyrosequencing. The study was conducted with four Arctic water samples, focusing on the eukaryotic picoplankton (0.4-3 µm), and with one sample collected in the Southern Ocean, examining the whole size spectrum (〉0.4 µm). For all individual samples, the protist community compositions suggested by the two different approaches showed significant similarities. Around 70% of the sequences detected by sequencing of clone libraries were also present in the 454-pyrosequencing data set. However, the clone library sequences reflected only ~20% of the abundant biosphere identified by 454-pyrosequencing and identified ribosomal sequences, that were not detected in the 454-pyrosequencing data sets.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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