Biodiversity of the marine ecosystem and carbon flux around Kerguelen (Southern Ocean) : role of small phytoplankton at the single cell level
This thesis focuses on small phytoplankton diversity (<20 µm) and its contribution to CO₂-fixation in contrasted marine ecosytems : the productive Kerguelen Plateau (KP) on the one hand and low productive surrounding waters on the other han. Iron-limited phytoplankton communities off-plateau are...
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Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
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2020
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Online Access: | https://theses.hal.science/tel-03178263 https://theses.hal.science/tel-03178263/document https://theses.hal.science/tel-03178263/file/These_Irion_Solene_version_definitive.pdf |
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ftunivlcoteopale:oai:HAL:tel-03178263v1 2024-06-23T07:48:04+00:00 Biodiversity of the marine ecosystem and carbon flux around Kerguelen (Southern Ocean) : role of small phytoplankton at the single cell level Biodiversité de l'écosystème marin et flux de carbone autour de Kerguelen (Océan Austral) : le rôle du petit phytoplancton à l'échelle de la cellule Irion, Solène 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 Urania Christaki Ludwig Jardillier 2020-11-19 https://theses.hal.science/tel-03178263 https://theses.hal.science/tel-03178263/document https://theses.hal.science/tel-03178263/file/These_Irion_Solene_version_definitive.pdf en eng HAL CCSD NNT: 2020DUNK0570 tel-03178263 https://theses.hal.science/tel-03178263 https://theses.hal.science/tel-03178263/document https://theses.hal.science/tel-03178263/file/These_Irion_Solene_version_definitive.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-03178263 Biodiversity. Université du Littoral Côte d'Opale, 2020. English. ⟨NNT : 2020DUNK0570⟩ Small phytoplankton Diatoms Carbon fixation Carbon export Sequencing NanoSIMS Chemotaxonomy Southern ocean Petit phytoplancton Diatomées Fixation de carbone Export de carbone Séquençage Chémotaxonomie Océan Austral [SDV.BID]Life Sciences [q-bio]/Biodiversity [SDV.EE.ECO]Life Sciences [q-bio]/Ecology environment/Ecosystems info:eu-repo/semantics/doctoralThesis Theses 2020 ftunivlcoteopale 2024-06-06T23:35:15Z This thesis focuses on small phytoplankton diversity (<20 µm) and its contribution to CO₂-fixation in contrasted marine ecosytems : the productive Kerguelen Plateau (KP) on the one hand and low productive surrounding waters on the other han. Iron-limited phytoplankton communities off-plateau are dominated by small cells all year long, whereas natural iron-fertilization over the KP promotes the seasonal development of chain-forming or large diatom blooms in spring and summer. Since the demonstration of natural iron fertilization on-plateau, the scientific community focused on large diatoms, assumed to promote carbon sequestration in the area. However, satellite data suggest that small phytoplankton dominate the phytoplankton communities outside of the bloom period on- and off-plateau. Consequently, this thesis had two main objectives. The first objective of this work was to obtain a precise image of the diversity of small and large phytoplankton after the diatom bloom (March 2018). A fragment of the 18S rRNA gene from small (0.2-20 µm) and large (20-100 µm) planktonic communities collected at discrete depths (down to 300 m), was sequenced (Illumina MiSeq) and used as an identity marker gene to determine the taxonomic diversity of small and large phytoplankton. At the surface, diatoms were dominant in the large-size fraction, while Phaeocystis antartica was particularly abundant in the small-size fraction, over the entire study area. As a whole, small phytoplankton communities were significantly different on- and off-plateau. High concentrations of silicic acid off-plateau favored the presence of a diverse assemblage of small diatoms, while high concentrations of ammonium on-plateau likely promoted the development of pico-sized Micromonas. Using chemotaxonomic pigments markers allowed the description of the temporal succession of phytoplankton communities on-plateau, dominated by diatoms from the onset to the decline of the bloom, while the contribution of small phytoplankton increased sharply after the bloom ... Doctoral or Postdoctoral Thesis antartic* Southern Ocean Université du Littoral Côte d'Opale portail Southern Ocean Austral Kerguelen |
institution |
Open Polar |
collection |
Université du Littoral Côte d'Opale portail |
op_collection_id |
ftunivlcoteopale |
language |
English |
topic |
Small phytoplankton Diatoms Carbon fixation Carbon export Sequencing NanoSIMS Chemotaxonomy Southern ocean Petit phytoplancton Diatomées Fixation de carbone Export de carbone Séquençage Chémotaxonomie Océan Austral [SDV.BID]Life Sciences [q-bio]/Biodiversity [SDV.EE.ECO]Life Sciences [q-bio]/Ecology environment/Ecosystems |
spellingShingle |
Small phytoplankton Diatoms Carbon fixation Carbon export Sequencing NanoSIMS Chemotaxonomy Southern ocean Petit phytoplancton Diatomées Fixation de carbone Export de carbone Séquençage Chémotaxonomie Océan Austral [SDV.BID]Life Sciences [q-bio]/Biodiversity [SDV.EE.ECO]Life Sciences [q-bio]/Ecology environment/Ecosystems Irion, Solène Biodiversity of the marine ecosystem and carbon flux around Kerguelen (Southern Ocean) : role of small phytoplankton at the single cell level |
topic_facet |
Small phytoplankton Diatoms Carbon fixation Carbon export Sequencing NanoSIMS Chemotaxonomy Southern ocean Petit phytoplancton Diatomées Fixation de carbone Export de carbone Séquençage Chémotaxonomie Océan Austral [SDV.BID]Life Sciences [q-bio]/Biodiversity [SDV.EE.ECO]Life Sciences [q-bio]/Ecology environment/Ecosystems |
description |
This thesis focuses on small phytoplankton diversity (<20 µm) and its contribution to CO₂-fixation in contrasted marine ecosytems : the productive Kerguelen Plateau (KP) on the one hand and low productive surrounding waters on the other han. Iron-limited phytoplankton communities off-plateau are dominated by small cells all year long, whereas natural iron-fertilization over the KP promotes the seasonal development of chain-forming or large diatom blooms in spring and summer. Since the demonstration of natural iron fertilization on-plateau, the scientific community focused on large diatoms, assumed to promote carbon sequestration in the area. However, satellite data suggest that small phytoplankton dominate the phytoplankton communities outside of the bloom period on- and off-plateau. Consequently, this thesis had two main objectives. The first objective of this work was to obtain a precise image of the diversity of small and large phytoplankton after the diatom bloom (March 2018). A fragment of the 18S rRNA gene from small (0.2-20 µm) and large (20-100 µm) planktonic communities collected at discrete depths (down to 300 m), was sequenced (Illumina MiSeq) and used as an identity marker gene to determine the taxonomic diversity of small and large phytoplankton. At the surface, diatoms were dominant in the large-size fraction, while Phaeocystis antartica was particularly abundant in the small-size fraction, over the entire study area. As a whole, small phytoplankton communities were significantly different on- and off-plateau. High concentrations of silicic acid off-plateau favored the presence of a diverse assemblage of small diatoms, while high concentrations of ammonium on-plateau likely promoted the development of pico-sized Micromonas. Using chemotaxonomic pigments markers allowed the description of the temporal succession of phytoplankton communities on-plateau, dominated by diatoms from the onset to the decline of the bloom, while the contribution of small phytoplankton increased sharply after the bloom ... |
author2 |
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 Urania Christaki Ludwig Jardillier |
format |
Doctoral or Postdoctoral Thesis |
author |
Irion, Solène |
author_facet |
Irion, Solène |
author_sort |
Irion, Solène |
title |
Biodiversity of the marine ecosystem and carbon flux around Kerguelen (Southern Ocean) : role of small phytoplankton at the single cell level |
title_short |
Biodiversity of the marine ecosystem and carbon flux around Kerguelen (Southern Ocean) : role of small phytoplankton at the single cell level |
title_full |
Biodiversity of the marine ecosystem and carbon flux around Kerguelen (Southern Ocean) : role of small phytoplankton at the single cell level |
title_fullStr |
Biodiversity of the marine ecosystem and carbon flux around Kerguelen (Southern Ocean) : role of small phytoplankton at the single cell level |
title_full_unstemmed |
Biodiversity of the marine ecosystem and carbon flux around Kerguelen (Southern Ocean) : role of small phytoplankton at the single cell level |
title_sort |
biodiversity of the marine ecosystem and carbon flux around kerguelen (southern ocean) : role of small phytoplankton at the single cell level |
publisher |
HAL CCSD |
publishDate |
2020 |
url |
https://theses.hal.science/tel-03178263 https://theses.hal.science/tel-03178263/document https://theses.hal.science/tel-03178263/file/These_Irion_Solene_version_definitive.pdf |
geographic |
Southern Ocean Austral Kerguelen |
geographic_facet |
Southern Ocean Austral Kerguelen |
genre |
antartic* Southern Ocean |
genre_facet |
antartic* Southern Ocean |
op_source |
https://theses.hal.science/tel-03178263 Biodiversity. Université du Littoral Côte d'Opale, 2020. English. ⟨NNT : 2020DUNK0570⟩ |
op_relation |
NNT: 2020DUNK0570 tel-03178263 https://theses.hal.science/tel-03178263 https://theses.hal.science/tel-03178263/document https://theses.hal.science/tel-03178263/file/These_Irion_Solene_version_definitive.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1802638484385562624 |