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  • 1
    Publication Date: 2015-12-14
    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.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
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    WILEY-BLACKWELL PUBLISHING
    In:  EPIC3Journal of Phycology, WILEY-BLACKWELL PUBLISHING, 49(5), pp. 996-1010, ISSN: 0022-3646
    Publication Date: 2019-07-16
    Description: In this study we present the first comprehensive analyses of the diversity and distribution of marine protist (micro- nano- and picoeukaryotes) in the Western Fram Strait, using 454-pyrosequencing and high-pressure liquid chromatography (HPLC) at five stations in summer 2010. Three stations (T1; T5; T7) were influenced by Polar Water, characterized by cold water with lower salinity (〈33) and different extents of ice-concentrations. Atlantic Water influenced the other two stations (T6; T9). While T6 was located in the mixed water zone characterized by cold water with intermediate salinity (~33) and high ice-concentrations, T9 was located in warm water with high salinity (~35) and no ice-coverage at all. General trends in community structure according to prevailing environmental settings, observed with both methods, coincided well. At two stations, T1 and T7, characterized by lower ice concentrations, diatoms (Fragilariopsis sp., Porosira sp., Thalassiosira spp.) dominated the protist community. The third station (T5) was ice-covered, but has been ice-free for ~4 weeks prior to sampling. At this station, dinoflagellates (Dinophyceae 1, Woloszynskia sp. and Gyrodinium sp.) were dominant, reflecting a post-bloom situation. At station T6 and T9, the protist communities consisted mainly of picoeukaryotes, e.g. Micromonas spp. Based on our results, 454-pyrosequencing has proven to be an adequate tool to provide comprehensive information on the composition of protist communities. Furthermore, this study suggests that a snap-shot of a few, but well-chosen samples can already provide an overview of community structure patterns and successions in a dynamic marine environment.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 3
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    WILEY-BLACKWELL PUBLISHING
    In:  EPIC3Polar Research, WILEY-BLACKWELL PUBLISHING, 33, ISSN: 0800-0395
    Publication Date: 2015-03-05
    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 diversity 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. On the high taxonomic level, both habitats showed very similar community structures, dominated by chrysophytes and chlorophytes. On the 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 relatively high similarity in diversity is a consequence of melt pond freshwater seeping through porous sea ice in late summer. Differences in the abundant biosphere nevertheless indicate that differences in both habitats are also strong enough to select for different dominant species.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
    Location Call Number Limitation Availability
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