Understanding annual plankton succession and its modifications in the context of past, present and future climate change

• Main Author: Kléparski, Loïck
• Other Authors: Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Nord ), Université du Littoral Côte d'Opale, Grégory Beaugrand, Clare Ostle
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2022
• Subjects: Global Alliance of the CPR survey; Annual plankton succession; METAL Theory; Climate change; Succession annuelle planctonique; Théorie METAL; Changement climatique; [SDV.EE.BIO]Life Sciences [q-bio]/Ecology; environment/Bioclimatology; North Atlantic
• Online Access: https://theses.hal.science/tel-03940277; https://theses.hal.science/tel-03940277/document; https://theses.hal.science/tel-03940277/file/113838_KLEPARSKI_2022_archivage.pdf

The spatial arrangement of biodiversity and annual plankton succession are key phenomena influencing ocean biogeochemistry (e.g. the biological pump) and the life cycle of many species. Biodiversity and phenological shifts induced by climate change might alter species succession and lead to trophic desynchronization and community reorganisation in space and time. The aim of this PhD is to improve our understanding of plankton biodiversity and phenology by identifying factors and processes that control them and by modelling the annual plankton succession in the context of global climate change. To do so, we used an approach based on the MacroEcological Theory on the Arrangement of Life (METAL) and observations collected by the Continuous Plankton Recorder (CPR) survey. To understand how annual plankton succession and species phenology will be altered in the context of global warming, it is important to identify what parameters and processes control these phenomena. Therefore, in the first part of this PhD, we describe the seasonal variations of major phytoplanktonic taxa in the North Sea and demonstrate that species' phenology results from the interaction between species' niche and the environment. We also show that diatoms with similar cell shape have also similar phenology and niches, i.e. that oblates (flattened cells) dominate the spring and autumn periods whereas prolates (elongated cells) dominate the summer period. We therefore establish a salient link between functional traits, the niche and the phenology. In the second part, we examine the spatio-temporal organisation of plankton biodiversity in the North Atlantic Ocean and show that this region is characterised by large spatial coenoclines (i.e. gradient of biocoenosis or community) induced by the niche-environment interaction. We also develop a new method, called a "species chromatogram", that gives a graphical summary of the niche by representing together abundance gradients along various environmental dimensions. This method can be used to ...