Study of diatom/copepod interactions on carbon export in a context of climate change
The biological carbon pump transfers CO2 from the atmosphere to the deep ocean as particulate organic matter. By forming aggregates, diatoms contribute strongly to the particle flux. Copepods, in terms of abundance and diversity, dominate zooplankton assemblages, are the main consumers of diatoms an...
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Other Authors: | , , , , , , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
Published: |
HAL CCSD
2020
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Subjects: | |
Online Access: | https://hal.science/tel-03114056 https://hal.science/tel-03114056/document https://hal.science/tel-03114056/file/2020_10_15_Toullec_Th%C3%A8se.pdf |
Summary: | The biological carbon pump transfers CO2 from the atmosphere to the deep ocean as particulate organic matter. By forming aggregates, diatoms contribute strongly to the particle flux. Copepods, in terms of abundance and diversity, dominate zooplankton assemblages, are the main consumers of diatoms and play and key role in the carbon export via faecal pellets egestion. Nutrient limitations mainly occur at the end of phytoplankton blooms, but are also an expected consequence of global warming. The aim of the thesis is to evaluate the role of copepod/diatom interactions on carbon export in a context of climate change. The results obtained show that nutrient limitations affecting diatoms biochemical composition, that influences copepods feeding activity and the export efficiency of faecal pellets. I have also shown that the functional traits of copepods can influence both the aggregates formation and their dynamics. Finally, using data from an oceanographic campaign carried out during the Arctic phytoplankton spring bloom, I observed that silicon limitation after sea ice retreat contributes to the aggregates formation. Copepods, at the end of the bloom migrate under the mixing layer where the aggregates are most abundant, which may suggest that the aggregates could be used as a food. La pompe biologique de carbone transfère le CO2 de l’atmosphère vers l’océan profond sous forme de matière organique particulaire. En formant des agrégats, les diatomées contribuent fortement au flux de particules. Les copépodes, en terme d’abondance et de diversité, dominentle zooplancton, sont les principaux consommateurs des diatomées et jouent un rôle important dans l’export de carbone via l’émission de pelotes fécales. Les limitations en sels nutritifs surviennent majoritairement en fin d’efflorescence phytoplanctonique, mais sont également une conséquence attendue du réchauffement global. L’objectif de la thèse vise à évaluer le rôle des interactions copépodes/diatomées sur l’export de carbone, dans un contexte de changement ... |
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