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The effects of pH-induced changes in seawater carbonate chemistry on inorganic carbon (C(i)) acquisition and domoic acid (DA) production were studied in two potentially toxic diatom species, Pseudo-nitzschia multiseries and Nitzschia navis-varingica, and the non-toxic Stellarima stellaris. In vivo activities of carbonic anhydrase (CA), photosynthetic O(2)(More)
a r t i c l e i n f o Keywords: CCM 13 C fractionation CA C 4 photosynthesis PEPC RubisCO The effect of pCO 2 on carbon acquisition and intracellular assimilation was investigated in the three bloom-forming diatom species, Eucampia zodiacus (Ehrenberg), Skeletonema costatum (Greville) Cleve, Thalassio-nema nitzschioides (Grunow) Mereschkowsky and the(More)
The potential interactive effects of iron (Fe) limitation and Ocean Acidification in the Southern Ocean (SO) are largely unknown. Here we present results of a long-term incubation experiment investigating the combined effects of CO2 and Fe availability on natural phytoplankton assemblages from the Weddell Sea, Antarctica. Active Chl a fluorescence(More)
Various protective and metabolic functions for coccolithophore calcification have been proposed such as providing a means to supply CO 2 for photosynthesis. It has also been speculated that calcification helps to dissipate excess energy under high irradiance, thereby circumventing photoinhibition. To address these questions, cells of a calcifying strain of(More)
a r t i c l e i n f o Information on interaction of C and N at the cellular level is lacking for ecologically relevant phytoplankton species. We examined the effects of NO 3-availability on C and N fluxes in the widely distributed marine coccolithophore Emiliania huxleyi. Cells were cultured at replete (∼280 μM) and ambient (∼10 μM) NO 3-, the latter(More)
In recent studies the Sr/Ca ratio of coccolithophore calcite was used as a proxy for past coccolithophore growth and calcification rates. Since Sr and Ca concentrations in seawater have not remained constant through time, interpretation of Sr/Ca data from the coccolith-dominated sedimentary record requires knowledge about the incorporation of seawater Sr(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)
Despite the fact that ocean acidification is considered to be especially pronounced in the Southern Ocean, little is known about CO 2-dependent physiological processes and the interactions of Antarctic phytoplankton key species. We therefore studied the effects of CO 2 partial pressure (P CO 2) (16.2, 39.5, and 101.3 Pa) on growth and photosynthetic carbon(More)
We present results from a field study of inorganic carbon (C) acquisition by Ross Sea phytoplankton during Phaeocystis-dominated early season blooms. Isotope disequilibrium experiments revealed that HCO 3) was the primary inorganic C source for pho-tosynthesis in all phytoplankton assemblages. From these experiments, we also derived relative enhancement(More)
a r t i c l e i n f o The present study examines how different pCO 2 acclimations affect the CO 2-and light-dependence of photophysiological processes and O 2 fluxes in four Southern Ocean (SO) key phytoplankton species. We grew Chaetoceros debilis (Cleve), Pseudo-nitzschia subcurvata (Hasle), Fragilariopsis kerguelensis (O'Meara) and Phaeocystis antarctica(More)