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  • Norwegian Polar Institute  (1)
  • OXFORD UNIV PRESS  (1)
  • SPRINGER  (1)
  • Wiley-Blackwell ; BioOne  (1)
  • Nature Research
  • 2010-2014  (4)
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Year
  • 1
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    Wiley-Blackwell ; BioOne
    In:  Journal of Eukaryotic Microbiology, 61 (6). pp. 569-579.
    Publication Date: 2015-03-13
    Description: Investigation of marine eukaryotic picoplankton composition is limited by missing morphological features for appropriate identification. Consequently, molecular methods are required. In this study, we used 454-pyrosequencing to study picoplankton communities at four stations in the West Spitsbergen Current (WSC; Fram Strait). High abundances of Micromonas pusilla were detected in the station situated closest to Spitsbergen, as seen in surveys of picoplankton assemblages in the Beaufort Sea. At the other three stations, other phylotypes, affiliating with Phaeocystis pouchetii and Syndiniales in the phylogenetic tree, were present in high numbers, dominating most of them. The picoplankton community structures at three of the stations, all with similar salinity and temperature, were alike. At the fourth station, the influence of the East Spitsbergen Current, transporting cold water from the Barents Sea around Spitsbergen, causes different abiotic parameters that result in a significantly different picoeukaryote community composition, which is dominated by M. pusilla. This observation is particularly interesting with regard to ongoing environmental changes in the Arctic. Ongoing warming of the WSC could convey a new picoplankton assemblage into the Arctic Ocean, which may come to affect the dominance of M. pusilla.
    Type: Article , PeerReviewed
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  • 2
    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
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  • 3
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    OXFORD UNIV PRESS
    In:  EPIC3Journal of Plankton Research, OXFORD UNIV PRESS, ISSN: 0142-7873
    Publication Date: 2018-02-16
    Description: Phytoplankton community analysis is important with respect to natural or humaninduced changes in the marine environment. Because of the efforts involved and the limitations of traditional methods, molecular sensing approaches are becoming more popular. Among others, microarray techniques targeting ribosomal 18S sequences have been successfully applied for phytoplankton investigation. In this contribution, we compared the results of two microarray methods targeting 18S rDNA and 18S rRNA with the results obtained from microscopy, HPLC and flow cytometry. On a qualitative basis, the microarrays showed similar or potentially better performance than the non-molecular methods. Quantitatively, our data suggest that microarray signals obtained from 18S rDNA provide relatively rough estimates of phytoplankton abundance. In contrast, when targeting 18S rRNA instead, a robust linear relationship (r2 ¼ 0.68) between molecular sensing signal and microscopic cell counts could be demonstrated using a probe specific to the genus Pseudo-nitzschia as an example. Thus, for both qualitative and quantitative purposes, microarray techniques can be valuable additions to traditional methods for phytoplankton analysis. Routine monitoring approaches in particular could benefit from advantages like reduced effort, higher taxonomic resolution and a potential for automation.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
    Publication Date: 2014-04-23
    Description: Knowledge about the protist diversity of the Pacific sector of the Southern Ocean is scarce. We tested the hypothesis that distinct protist community assemblages characterize large-scale water masses. Therefore, we determined the composition and biogeography of late summer protist assemblages along a transect from the coast of New Zealand to the eastern Ross Sea. We used state of the art molecular approaches, such as automated ribosomal intergenic spacer analysis and 454-pyrosequencing, combined with high-performance liquid chromatography pigment analysis to study the protist assemblage. We found distinct biogeographic patterns defined by the environmental conditions in the particular region. Different water masses harbored different microbial communities. In contrast to the Arctic Ocean, picoeukaryotes had minor importance throughout the investigated transect and showed very low contribution south of the Polar Front. Dinoflagellates, Syndiniales, and small stramenopiles were dominating the sequence assemblage in the Subantarctic Zone, whereas the relative abundance of diatoms increased southwards, in the Polar Frontal Zone and Antarctic Zone. South of the Polar Front, most sequences belonged to haptophytes. This study delivers a comprehensive and taxon detailed overview of the protist composition in the investigated area during the austral summer 2010.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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