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Distribution of unicellular plankton organisms in the 'AWI Hausgarten' (79°N/4°E) during summer in relation to a changing Arctic environment
Mebrahtom, Y. (2011). Distribution of unicellular plankton organisms in the 'AWI Hausgarten' (79°N/4°E) during summer in relation to a changing Arctic environment. MSc Thesis. Alfred Wegener Institute for Polar and Marine Research: Bremen. 58 pp.

Thesis info:
    Alfred Wegener Institute for Polar- and Marine Research (AWI), more

Available in Author 
    VLIZ: Non-open access 227013
Document type: Dissertation

Keywords
    Climatic changes; Diatoms; Neritic zone; Phytoplankton; Emiliania huxleyi (Lohmann) W.W.Hay & H.P.Mohler, 1967 [WoRMS]; Emiliania huxleyi (Lohmann) W.W.Hay & H.P.Mohler, 1967 [WoRMS]; Phaeocystis pouchetii (Hariot) Lagerheim, 1896 [WoRMS]; PN, Arctic [Marine Regions]; Marine
Author keywords
    Arctic Ocean; Climate warming; Central station HAUSGARTEN; Fram Strait; Phytoplankton community; Neritic diatom species; Oceanic diatom species; Emiliania huxleyi; Phaeocystis pouchetii.

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  • Mebrahtom, Y.

Abstract
    The Arctic Ocean in the northern high latitudes is most vulnerable and sensitive to climatic changes and has received increasing attention recently because of the drastic decrease of sea ice cover and extent. Loss of Arctic sea ice has accelerated recently, culminating in a 2007 summer minimum ice extent that was 23% below the previous minimum recorded in 2005. These changes in the physical environment will eventually have enormous consequences for the pelagic system, as well as for the export of organic matter from the productive layer to the deep sea. Sedimentation and composition of particulate matter are studied at the AWI- HAUSGARTEN – long term deep sea observatory, found in the eastern Fram Strait at 79°N/4°E since 2000 by means of year round moored sediment traps in order to monitor seasonal and annual changes in connection to environmental settings. For this task knowledge on phytoplankton, the main primary producers, its composition and amount in the water column, are of great significance. Water samples collected from several depth ranges from the central station at the Hausgarten during six summer expeditions in 1998, 2003, 2004, 2006, 2007, and 2010 with the RV Polarstern were investigated to quantitatively as well as qualitatively determine the distribution, and composition of the dominant major groups of species of phytoplankton and/or protozooplankton and their possible change throughout the time period study in relation to environmental factors such as temperature, salinity and sea ice cover. Diatoms were the dominant major groups in the years 1998 and 2003 characterized by longer periods of sea ice cover and a relatively colder temperature. Coccolithophorids mainly composed of Emiliania huxleyi dominated the water samples from 2004. The water samples from station 788, 2006; station 213, 2007; and station 173, 2010 characterized by warmer temperatures and very low or by the complete absence of sea ice and highly influenced by the inflow of a relatively warmer and saline nutrient rich Atlantic water carried by the West Spitsbergen Current were completely dominated by the prymnesiophyte Phaeocystis pouchetii. Quantitative phytoplankton analysis showed a shift from larger diatoms to smaller sized cells mainly Phaeocystis.

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