Sebastian Rokitta

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The effects of ocean acidification on the life-cycle stages of the coccolithophore Emiliania huxleyi and their modulation by light were examined. Calcifying diploid and noncalcifying haploid cells (Roscoff culture collection strains 1216 and 1217) were acclimated to present-day and elevated CO2 partial pressures (PCO2; 38.5 vs. 101.3 Pa, i.e., 380 vs. 1000(More)
Coccolithophores, especially the abundant, cosmopolitan species Emiliania huxleyi (Lohmann) W. W. Hay et H. P. Mohler, are one of the main driving forces of the oceanic carbonate pump and contribute significantly to global carbon cycling, due to their ability to calcify. A recent study indicates that termination of diploid blooms by viral infection induces(More)
Effects of ocean acidification on Emiliania huxleyi strain RCC 1216 (calcifying, diploid life-cycle stage) and RCC 1217 (non-calcifying, haploid life-cycle stage) were investigated by measuring growth, elemental composition, and production rates under different pCO2 levels (380 and 950 μatm). In these differently acclimated cells, the photosynthetic carbon(More)
Ocean Acidification (OA) has been shown to affect photosynthesis and calcification in the coccolithophore Emiliania huxleyi, a cosmopolitan calcifier that significantly contributes to the regulation of the biological carbon pumps. Its non-calcifying, haploid life-cycle stage was found to be relatively unaffected by OA with respect to biomass production.(More)
Seawater carbonate chemistry is typically calculated from two measured parameters. Depending on the choice of these input parameters, discrepancies in calculated pCO2 have been recognized by marine chemists, but the significance of this phenomenon for CO2 perturbation experiments has so far not been determined. To mimic different 5 pCO2 scenarios, two(More)
A combined increase in seawater [CO2 ] and [H(+) ] was recently shown to induce a shift from photosynthetic HCO3 (-) to CO2 uptake in Emiliania huxleyi. This shift occurred within minutes, whereas acclimation to ocean acidification (OA) did not affect the carbon source. To identify the driver of this shift, we exposed low- and high-light acclimated E.(More)
1 Marine Biogeosciences, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany, 2 Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, 3 Instituto Milenio de Oceanografía de Chile, Concepción, Chile, 4 Centre National de la Recherche Scientifique, Station Biologique de Roscoff,(More)
Global change will affect patterns of nutrient upwelling in marine environments, potentially becoming even stricter regulators of phytoplankton primary productivity. To better understand phytoplankton nutrient utilization on the subcellular basis, we assessed the transcriptomic responses of the life-cycle stages of the biogeochemically important microalgae(More)
the PhytoChange project, leading me through the experiments and continuously supervising me throughout the work! Thanks you Björn for your providence in night and daytime! Thank you Uwe for your assistance, reviewing and guidance! I really owe you, guys! Further I like to thank Dr. Scarlett Trimborn, for the introduction into the laboratory work, for kind(More)