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Nitrate concentration of porewater in sediment profile PS31/009-5

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DOI: 10.1594/pangaea.206332
  • Ark-X/1
  • Giant Box Corer
  • Global Environmental Change: The Northern North Atlantic
  • Nitrate
  • Polarstern
  • Ps31
  • Ps31/009-5
  • Sfb313
  • Ecology


PowerPoint-Präsentation Mass sinking of individual species populations during an iron fertilization experiment in the Southern Ocean (EIFEX) Philipp Assmy*, Joachim Henjes*, Christine Klaas*, Oliver Sachs*, Eberhard Sauter*, Victor Smetacek* & Marina Montresor# *Alfred-Wegener-Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany #Stazione Zoologica 'A. Dohrn', Villa Comunale, 80121 Napoli, Italy I. The European Iron Fertilization Experiment (EIFEX), conducted in the Polar Frontal Zone of the Southern Ocean, induced a large phytoplankton bloom in the deeply mixed surface layer (Fig. 1). In the final week of the experiment the bloom crashed as indicated by decreasing chlorophyll concentrations. Fig. 5: Evidence of freshly deposited material underneath the EIFEX area (a-f): a) Sediment core with a 5 mm thick fluff layer. b) Chl-a fluorescence (arrow) of an intact dinoflagellate cell in ~3600 m; scale bar: 50 µm. c) High bacterial activity on a colonised cell of Corethron sp. in the fluff layer; scale bar: 50 µm. d) SEM micrograph of an intact chain of Chaetoceros atlanticus; scale bar: 20 µm. e) Lorica of the tintinnid ciliate Cymatocylis sp.; scale bar: 50 µm. f) fecal pellet containing diatom debris; scale bar: 100 µm. Fig. 1: Temporal and vertical evolution of the iron-induced bloom over the course of EIFEX. Conclusions. During EIFEX the fate of an iron-induced bloom was followed in detail. For the first time the massive sinking event down the water column to the sea floor, in the aftermath of the iron-induced bloom, was examined from an ecological viewpoint at the species population level. The findings confirm similarity between oceanic and coastal blooms but raise intriguing questions concerning the evolutionary ecology of phytoplankton populations. Fig. 2: a) Average mixed layer (upper 100 m) abundance of full cells over the course of EIFEX: 1) Chaetoceros dichaeta

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