Facteurs de contrôle de l'activité et de la diversité du bactérioplancton dans des réservoirs de différents niveaux trophiques

Abstract : The aim of this PhD study was to determine the factors controlling bacterioplankton along a trophic gradient The first step consisted to monitor bacterial (density, biovolume, activities and diversity) and biological (heterotrophic protozooplanctonic abundance, phytoplancton, mesoplancton et viruses) and physico-chemical (temperature, oxygen, nutrients,...) seasonal dynamics. In a second step, the impacts of bottom-up factors (ressources) and top-down factors (predation) were tested by in situ experiments. The seasonal pattern allowed to determine some key-periods in the year and to realise experiments during these periods. It allowed to show an identical bacterial dynamics of the activities whatever the reservoir and the preponderance of ascending factors. The in situ experiments showed that bacteria seemed strongly controlled by the resources, including eutrophic middle. On the other hand the predators have few impact on the bacterial activity. Furthermore, the activity itself depends on the present nutriments and not on the bacterial diversity. While intensity of activity seems connected to the capacities of bacterial communities. Heterotrophic nanoflagellates seem significantly involved in bacterial community composition but during a restricted time. The predation appears as a control for maintaining the diversity by limiting the abundance of the most competitive bacteria which take advantage of resources.
Document type :
Theses
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-00717766
Contributor : Camille Meyer <>
Submitted on : Friday, July 13, 2012 - 3:44:25 PM
Last modification on : Thursday, January 11, 2018 - 6:23:13 AM
Long-term archiving on : Sunday, October 14, 2012 - 3:15:37 AM

Identifiers

  • HAL Id : tel-00717766, version 1

Collections

Citation

Sébastien Delgoulet. Facteurs de contrôle de l'activité et de la diversité du bactérioplancton dans des réservoirs de différents niveaux trophiques. Biochimie, Biologie Moléculaire. Université Blaise Pascal - Clermont-Ferrand II; Université d'Auvergne - Clermont-Ferrand I, 2007. Français. ⟨NNT : 2007CLF21733⟩. ⟨tel-00717766⟩

Share

Metrics

Record views

241

Files downloads

1325