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Dynamique bactérienne en Manche orientale - Relations avec les poussées de Phaeocystis globosa.

Abstract : Bacterial dynamics (total, viable and active abundances, biomass and cell production, exo-enzymatic activities) was estimated in the eastern English Channel, from an ecosystemic approach to the use of specific microbial tools. It allows better understanding the role of heterotrophic bacteria, little studied in the eastern English Channel to date, in matter and energy fluxes, specially during phytoplankton bloom.
The first aim was to determine the bacterial response to the space and time variability of the environmental conditions, at (i) the ecosystem scale during two consecutive years (2003/2004), (ii) the seasonal scale in Wimereux location and (iii) at the diurnal scale during Lagrangian drifts. This study highlights two different years in terms of microbial food web functioning. In addition, the diversity of factors controlling the bacterial dynamics (temperature, organic matter availability, grazing pressure) governs its seasonality. During a diurnal cycle, the use of two bacterial production methods allowed a more accurate and finer analyse of bacterial processes.
In order to estimate the trophic role of bacterioplankton, particularly during the massive Phaeocystis globosa blooms, estimations of the bacterial viable and active cellular fractions, responsible for the bulk of bacterial activities, were made. Bacterial abundance significantly increased in response to organic matter accumulation during and after the bloom. Exo-enzymatic activities highlighted a significant bacterial degradation of the phytoplankton-derived organic matter, and emphasized the strong “trophic” relation linking bacteria and P. globosa.
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Contributor : Dominique Lamy <>
Submitted on : Thursday, October 12, 2006 - 5:49:25 PM
Last modification on : Tuesday, January 12, 2021 - 3:25:11 AM
Long-term archiving on: : Friday, November 25, 2016 - 12:02:23 PM


  • HAL Id : tel-00105902, version 1



Dominique Lamy. Dynamique bactérienne en Manche orientale - Relations avec les poussées de Phaeocystis globosa.. Ecologie, Environnement. Université du Littoral Côte d'Opale, 2006. Français. ⟨tel-00105902⟩



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