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Dynamics of bacteria, phytoplankton and extracellular carbohydrates during blooms of the coccolithophore Emiliania huxleyi

Nicolas Van Oostende UGent (2011)
abstract
The composition of bacterial and phytoplankton communities during phytoplankton blooms, and their interactions, are important properties of the microbial food web, which can potentially have a strong impact on the fate of organic matter and hence carbon cycling in the world’s oceans. During late spring (May-June 2006-2008) we investigated the relationship between the community structures of phytoplankton (pigment-based) and free-living and particle-associated bacterioplankton (denaturant gradient gel electrophoresis), and environmental constraints during natural coccolithophore blooms along the North East Atlantic continental margin (Bay of Biscay). The alternation between diatom and coccolithophore blooms (mainly Emiliania huxleyi) of similar biomass was partly driven by changes in nutrient stoichiometry (N:P and dSi:N). High concentrations of transparent exopolymer particles (TEP) were associated with stratified, coccolithophore-rich water masses. Free-living and particle-associated bacterial communities had different typical representatives but showed a considerable overlap in composition. Furthermore, the structure of the bacterial communities was significantly correlated to the abundance of phytoplankton groups and water column stratification. At selected stations, we assessed the relationship of dimethyl sulphide (DMS) and dimethylsulphonioproprionate (DMSP) concentrations and the fate of phytoplankton in terms of cell lysis rates and microzooplankton grazing. Coccolithophores constituted an important source of particulate DMSP, and cell lysis enhanced the release of dissolved DMSP. Finally, we assessed the role of bacterial activity and life cycle stage of the coccolithophore E. huxleyi on the dynamics of dissolved carbohydrates and TEP by measuring their production and composition during the stationary growth phase of batch cultures, and by tracing the fate of photosynthetically fixed carbon by stable isotope probing in non-axenic calcifying E. huxleyi cultures using liquid chromatographic separation of high molecular weight neutral aldoses (HMW NAld) combined with isotope ratio mass spectrometry. Bacteria favoured the accumulation of polysaccharides and the formation of TEP, and enhanced their aggregation in calcifying E. huxleyi cultures. The production of coccoliths was probably the main source of HMW NAld in our non-axenic calcifying E. huxleyi cultures. Extracellular release of carbon in the dissolved and the particulate pools reached up to 76% of total primary production during the stationary growth phase of E. huxleyi.
Please use this url to cite or link to this publication:
author
promoter
UGent, Eric Boschker and UGent
organization
year
type
dissertation (monograph)
subject
keyword
Emiliania huxleyi, coccolithophore, phytoplankton, free-living bacteria, Bay of Biscay, particle-associated bacteria, transparent exopolymer particles, dissolved carbohydrate, DMSP, neutral aldose, LC/IRMS, DGGE
pages
269 pages
publisher
Ghent University. Faculty of Sciences
place of publication
Ghent, Belgium
defense location
Gent : Het Pand (zaal Refter)
defense date
2011-09-15 16:00
language
English
UGent publication?
yes
classification
D1
additional info
dissertation consists of copyrighted material
copyright statement
I have transferred the copyright for this publication to the publisher
id
1919906
handle
http://hdl.handle.net/1854/LU-1919906
date created
2011-10-03 16:17:23
date last changed
2011-10-04 10:03:46
@phdthesis{1919906,
  abstract     = {The composition of bacterial and phytoplankton communities during phytoplankton blooms, and their interactions, are important properties of the microbial food web, which can potentially have a strong impact on the fate of organic matter and hence carbon cycling in the world{\textquoteright}s oceans.
During late spring (May-June 2006-2008) we investigated the relationship between the community structures of phytoplankton (pigment-based) and free-living and particle-associated bacterioplankton (denaturant gradient gel electrophoresis), and environmental constraints during natural coccolithophore blooms along the North East Atlantic continental margin (Bay of Biscay). The alternation between diatom and coccolithophore blooms (mainly Emiliania huxleyi) of similar biomass was partly driven by changes in nutrient stoichiometry (N:P and dSi:N). High concentrations of transparent exopolymer particles (TEP) were associated with stratified, coccolithophore-rich water masses. Free-living and particle-associated bacterial communities had different typical representatives but showed a considerable overlap in composition. Furthermore, the structure of the bacterial communities was significantly correlated to the abundance of phytoplankton groups and water column stratification. At selected stations, we assessed the relationship of dimethyl sulphide (DMS) and dimethylsulphonioproprionate (DMSP) concentrations and the fate of phytoplankton in terms of cell lysis rates and microzooplankton grazing. Coccolithophores constituted an important source of particulate DMSP, and cell lysis enhanced the release of dissolved DMSP. Finally, we assessed the role of bacterial activity and life cycle stage of the coccolithophore E. huxleyi on the dynamics of dissolved carbohydrates and TEP by measuring their production and composition during the stationary growth phase of batch cultures, and by tracing the fate of photosynthetically fixed carbon by stable isotope probing in non-axenic calcifying E. huxleyi cultures using liquid chromatographic separation of high molecular weight neutral aldoses (HMW NAld) combined with isotope ratio mass spectrometry. Bacteria favoured the accumulation of polysaccharides and the formation of TEP, and enhanced their aggregation in calcifying E. huxleyi cultures. The production of coccoliths was probably the main source of HMW NAld in our non-axenic calcifying E. huxleyi cultures. Extracellular release of carbon in the dissolved and the particulate pools reached up to 76\% of total primary production during the stationary growth phase of E. huxleyi.},
  author       = {Van Oostende, Nicolas},
  keyword      = {Emiliania huxleyi,coccolithophore,phytoplankton,free-living bacteria,Bay of Biscay,particle-associated bacteria,transparent exopolymer particles,dissolved carbohydrate,DMSP,neutral aldose,LC/IRMS,DGGE},
  language     = {eng},
  pages        = {269},
  publisher    = {Ghent University. Faculty of Sciences},
  school       = {Ghent University},
  title        = {Dynamics of bacteria, phytoplankton and extracellular carbohydrates during blooms of the coccolithophore Emiliania huxleyi},
  year         = {2011},
}

Chicago
Van Oostende, Nicolas. 2011. “Dynamics of Bacteria, Phytoplankton and Extracellular Carbohydrates During Blooms of the Coccolithophore Emiliania Huxleyi”. Ghent, Belgium: Ghent University. Faculty of Sciences.
APA
Van Oostende, N. (2011). Dynamics of bacteria, phytoplankton and extracellular carbohydrates during blooms of the coccolithophore Emiliania huxleyi. Ghent University. Faculty of Sciences, Ghent, Belgium.
Vancouver
1.
Van Oostende N. Dynamics of bacteria, phytoplankton and extracellular carbohydrates during blooms of the coccolithophore Emiliania huxleyi. [Ghent, Belgium]: Ghent University. Faculty of Sciences; 2011.
MLA
Van Oostende, Nicolas. “Dynamics of Bacteria, Phytoplankton and Extracellular Carbohydrates During Blooms of the Coccolithophore Emiliania Huxleyi.” 2011 : n. pag. Print.