Spatial and temporal patterns in diatom-prokaryote associations in the Southern Ocean

• Main Author: Liu, Yan
• Other Authors: Sorbonne université, Obernosterer, Ingrid
• Format: Thesis
• Language: English
• Published: 2019
• Subjects: Diatomées; Procaryotes; Interaction; Océan Austral; Kerguelen; Séquençage; Diatoms; Prokaryotes; Interactions; Southern Ocean; Kerguelen plateau; Diversity; envir; geo; Austral
• Online Access: http://www.theses.fr/2019SORUS213/document

The interplay among microorganisms profoundly impacts biogeochemical cycles in the ocean. However, the questions of how microbes associated with each other on the spatial and temporal scale, and whether the associations of diatom-prokaryote and of DOM-prokaryote affect the distributions of these three components are open. In chapter 1, we observed distinct compositions of diatom and prokaryotic communities among the major ocean zones. Significant relationships between compositional changes of diatoms and of prokaryotes were found. In chapter 2, we observed two consecutive phytoplankton blooms, each composed of distinct diatom assemblages. Using network analysis, we identified two groups of diatoms representative of the spring and summer bloom, respectively, that had opposite correlation patterns with prokaryotic taxa. In chapter 3, we found the distinct composition of DOM and that of total and active prokaryotes on and off the plateau. The DOM-prokaryote correlations were overall stronger on the plateau than that off the plateau. The key active prokaryotic groups that strongly correlated with DOM were qualitatively similar in both ecosystems and quantitatively higher on the plateau. Taken together, our results demonstrate the significant associations between diatoms and prokaryotes, and between prokaryotes and DOM. The compositions of prokaryotic communities are influenced by both diatoms and DOM. L’interaction entre les micro-organismes a de profondes répercussions sur les cycles biogéochimiques de l’océan. Cependant, la question de savoir comment les microbes s’associent les uns aux autres aux échelles spatiale et temporelle et si les associations de diatom-procaryote et de DOM-procaryote affectent la distribution de ces trois composants est ouverte. Au chapitre 1, nous observons des compositions distinctes de diatomées et de communautés procaryotes parmi les principales zones océaniques. Des relations significatives entre les changements de composition des diatomées et des procaryotes ont été trouvées. Au ...