ORCID Profile
0000-0003-4765-3933
Current Organisation
Macau University of Science and Technology
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Publisher: Frontiers Media SA
Date: 26-02-2019
Publisher: Copernicus GmbH
Date: 13-11-2202
Abstract: Abstract. Marine phytoplankton have developed the remarkable ability to tightly regulate the concentration of free calcium ions in the intracellular cytosol at a level of ~ 0.1 μmol L−1 in the presence of seawater Ca2+ concentrations of 10 mmol L−1. The low cytosolic calcium ion concentration is of utmost importance for proper cell signalling function. While the regulatory mechanisms responsible for the tight control of intracellular Ca2+ concentration are not completely understood, phytoplankton taxonomic groups appear to have evolved different strategies, which may affect their ability to cope with changes in seawater Ca2+ concentrations in their environment on geological timescales. For ex le, the Cretaceous (145 to 66 Ma), an era known for the high abundance of coccolithophores and the production of enormous calcium carbonate deposits, exhibited seawater calcium concentrations up to 4 times present-day levels. We show that calcifying coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica and Coccolithus braarudii) are able to maintain their relative fitness (in terms of growth rate and photosynthesis) at simulated Cretaceous seawater calcium concentrations, whereas these rates are severely reduced under these conditions in some non-calcareous phytoplankton species (Chaetoceros sp., Ceratoneis closterium and Heterosigma akashiwo). Most notably, this also applies to a non-calcifying strain of E. huxleyi which displays a calcium sensitivity similar to the non-calcareous species. We hypothesize that the process of calcification in coccolithophores provides an efficient mechanism to alleviate cellular calcium poisoning and thereby offered a potential key evolutionary advantage, responsible for the proliferation of coccolithophores during times of high seawater calcium concentrations. The exact function of calcification and the reason behind the highly ornate physical structures of coccoliths remain elusive.
Publisher: Oxford University Press (OUP)
Date: 04-10-2016
Abstract: Exposure of the toxigenic dinoflagellate Alexandrium catenella to variations in pCO2 H, comparable to current and near-future levels observed in Southern Chilean fjords, revealed potential functional adaptation mechanisms. Under calculated conditions for pH(total scale) and pCO2 ranging from 7.73–8.66 to 69.7–721.3 μatm, respectively, the Chilean strain Q09 presented an optimum growth rate and dissolved inorganic carbon (DIC) uptake at near-equilibrium pCO2 H conditions (∼8.1). DistaLM analysis between physiological relevant carbonate system parameters (CO2, HCO3−, and H+) and cellular rates (growth rate and DIC uptake) identified HCO3− as the unique variable explaining a significant portion of the physiological response. Estimations of equivalent spherical diameter (ESD) and chain-formation index (CI) revealed reduced cell size and enhanced chain formation at high pH/low pCO2 conditions. Light intensity as co-factor during experiments (50 vs. 100 μmol photons m−2 s−1) produced no effect on ESD and CI. Cells exposed to low light however, had reduced cell growth and DIC uptake especially at high pH/low pCO2. We suggest that A. catenella Chilean strains are highly adapted to spatio-temporal pCO2 H fluctuations in Chilean fjords, becoming a resilient winner from expected climate change effects.
Publisher: Elsevier BV
Date: 10-2016
Publisher: MDPI AG
Date: 15-04-2015
DOI: 10.3390/JMSE3020154
Publisher: Springer Science and Business Media LLC
Date: 21-04-2017
Publisher: Springer Science and Business Media LLC
Date: 21-03-2017
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4AY02126F
Abstract: A new high performance chelation ion chromatography method for the simultaneous determination of trace magnesium and strontium in various calcium carbonate s les was developed.
Publisher: Inter-Research Science Center
Date: 02-07-2015
DOI: 10.3354/MEPS11309
Location: Brazil
Location: No location found
No related grants have been discovered for Marius N. Muller.