Diatom biodiversity and the modulation of biogeochemical fluxes of carbon and silicon in pelagic polar ecosystems
Polar regions are particularly affected by the ongoing climate changes which have profound consequences on the development of phytoplankton and on the functioning of the biological pump (vertical transfer of particulate organic carbon from the surface to the deep ocean). Plankton community structure...
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2021
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Online Access: | https://theses.hal.science/tel-03137420 https://theses.hal.science/tel-03137420/document https://theses.hal.science/tel-03137420/file/These_LAFOND.pdf |
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ftunivaixmarseil:oai:HAL:tel-03137420v1 2023-12-31T10:03:57+01:00 Diatom biodiversity and the modulation of biogeochemical fluxes of carbon and silicon in pelagic polar ecosystems Rôle de la biodiversité des diatomées dans la modulation des flux biogéochimiques du carbone et du silicium dans les milieux polaires Lafond, Augustin Institut méditerranéen d'océanologie (MIO) Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS) Aix Marseille Université Bernard Quéguiner Karine Leblanc 2021-01-08 https://theses.hal.science/tel-03137420 https://theses.hal.science/tel-03137420/document https://theses.hal.science/tel-03137420/file/These_LAFOND.pdf fr fre HAL CCSD tel-03137420 https://theses.hal.science/tel-03137420 https://theses.hal.science/tel-03137420/document https://theses.hal.science/tel-03137420/file/These_LAFOND.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-03137420 Océanographie. Aix Marseille Université, 2021. Français. ⟨NNT : ⟩ Diatoms Biological pump Community structure Baffin Bay Kerguelen Plateau Arctic Southern Ocean Biogeochemistry Diatomées Pompe biologique Structure des communautés Baie de Baffin Plateau des Kerguelen Arctique Océan Austral Biogéochimie [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry [SDE.BE]Environmental Sciences/Biodiversity and Ecology info:eu-repo/semantics/doctoralThesis Theses 2021 ftunivaixmarseil 2023-12-05T23:39:36Z Polar regions are particularly affected by the ongoing climate changes which have profound consequences on the development of phytoplankton and on the functioning of the biological pump (vertical transfer of particulate organic carbon from the surface to the deep ocean). Plankton community structure and species-specific properties (size, shape, cellular content in Si and C, physiological state, life stage, etc.) can strongly influence biogeochemical cycles and the export of organic matter (e.g. C, N) and biomineral (e.g. Si). In high latitudes, diatoms are a major contributor to primary production and exhibit a great diversity of species. The objectives of this PhD are (1) to identify the factors controlling the development and the structure of diatom communities, (2) to assess the influence of species diversity on the composition and stoichiometry of particulate matter, and (3) to understand mortality and export modes in the deep ocean. This work is based on the study of two subpolar regions located in both the northern and southern hemispheres: (1) the Baffin Bay, a seasonal ice zone in the Arctic, and (2) the Kerguelen region, a permanently open ocean zone in the Southern Ocean. In the latter region, we studied two contrasted environments: a low production HNLC (High Nutrient Low Chlorophyll) area versus a high production iron-fertilized area located above the Kerguelen plateau. In Baffin Bay, we highlight a diatom community succession in relation with sea ice melting and the strong west-to-east water masses gradient prevailing in the bay. A low productive community dominated by pennate diatoms was found beneath the consolidated ice pack (pre-bloom conditions), in ice-free Pacific influenced waters, and on the easternside of the bay (post-bloom conditions). In contrast, an actively growing diatom bloom composed of a mixed assemblage of centric (e.g. Chaetoceros, Thalassiosira) and pennate diatoms was found in the marginal ice zone. These results highlight the importance of the melting sea ice for the ... Doctoral or Postdoctoral Thesis Arctic Arctique* Baffin Bay Baffin Bay Baffin Baie de Baffin ice pack Phytoplankton Sea ice Southern Ocean Aix-Marseille Université: HAL |
institution |
Open Polar |
collection |
Aix-Marseille Université: HAL |
op_collection_id |
ftunivaixmarseil |
language |
French |
topic |
Diatoms Biological pump Community structure Baffin Bay Kerguelen Plateau Arctic Southern Ocean Biogeochemistry Diatomées Pompe biologique Structure des communautés Baie de Baffin Plateau des Kerguelen Arctique Océan Austral Biogéochimie [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry [SDE.BE]Environmental Sciences/Biodiversity and Ecology |
spellingShingle |
Diatoms Biological pump Community structure Baffin Bay Kerguelen Plateau Arctic Southern Ocean Biogeochemistry Diatomées Pompe biologique Structure des communautés Baie de Baffin Plateau des Kerguelen Arctique Océan Austral Biogéochimie [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry [SDE.BE]Environmental Sciences/Biodiversity and Ecology Lafond, Augustin Diatom biodiversity and the modulation of biogeochemical fluxes of carbon and silicon in pelagic polar ecosystems |
topic_facet |
Diatoms Biological pump Community structure Baffin Bay Kerguelen Plateau Arctic Southern Ocean Biogeochemistry Diatomées Pompe biologique Structure des communautés Baie de Baffin Plateau des Kerguelen Arctique Océan Austral Biogéochimie [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry [SDE.BE]Environmental Sciences/Biodiversity and Ecology |
description |
Polar regions are particularly affected by the ongoing climate changes which have profound consequences on the development of phytoplankton and on the functioning of the biological pump (vertical transfer of particulate organic carbon from the surface to the deep ocean). Plankton community structure and species-specific properties (size, shape, cellular content in Si and C, physiological state, life stage, etc.) can strongly influence biogeochemical cycles and the export of organic matter (e.g. C, N) and biomineral (e.g. Si). In high latitudes, diatoms are a major contributor to primary production and exhibit a great diversity of species. The objectives of this PhD are (1) to identify the factors controlling the development and the structure of diatom communities, (2) to assess the influence of species diversity on the composition and stoichiometry of particulate matter, and (3) to understand mortality and export modes in the deep ocean. This work is based on the study of two subpolar regions located in both the northern and southern hemispheres: (1) the Baffin Bay, a seasonal ice zone in the Arctic, and (2) the Kerguelen region, a permanently open ocean zone in the Southern Ocean. In the latter region, we studied two contrasted environments: a low production HNLC (High Nutrient Low Chlorophyll) area versus a high production iron-fertilized area located above the Kerguelen plateau. In Baffin Bay, we highlight a diatom community succession in relation with sea ice melting and the strong west-to-east water masses gradient prevailing in the bay. A low productive community dominated by pennate diatoms was found beneath the consolidated ice pack (pre-bloom conditions), in ice-free Pacific influenced waters, and on the easternside of the bay (post-bloom conditions). In contrast, an actively growing diatom bloom composed of a mixed assemblage of centric (e.g. Chaetoceros, Thalassiosira) and pennate diatoms was found in the marginal ice zone. These results highlight the importance of the melting sea ice for the ... |
author2 |
Institut méditerranéen d'océanologie (MIO) Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS) Aix Marseille Université Bernard Quéguiner Karine Leblanc |
format |
Doctoral or Postdoctoral Thesis |
author |
Lafond, Augustin |
author_facet |
Lafond, Augustin |
author_sort |
Lafond, Augustin |
title |
Diatom biodiversity and the modulation of biogeochemical fluxes of carbon and silicon in pelagic polar ecosystems |
title_short |
Diatom biodiversity and the modulation of biogeochemical fluxes of carbon and silicon in pelagic polar ecosystems |
title_full |
Diatom biodiversity and the modulation of biogeochemical fluxes of carbon and silicon in pelagic polar ecosystems |
title_fullStr |
Diatom biodiversity and the modulation of biogeochemical fluxes of carbon and silicon in pelagic polar ecosystems |
title_full_unstemmed |
Diatom biodiversity and the modulation of biogeochemical fluxes of carbon and silicon in pelagic polar ecosystems |
title_sort |
diatom biodiversity and the modulation of biogeochemical fluxes of carbon and silicon in pelagic polar ecosystems |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://theses.hal.science/tel-03137420 https://theses.hal.science/tel-03137420/document https://theses.hal.science/tel-03137420/file/These_LAFOND.pdf |
genre |
Arctic Arctique* Baffin Bay Baffin Bay Baffin Baie de Baffin ice pack Phytoplankton Sea ice Southern Ocean |
genre_facet |
Arctic Arctique* Baffin Bay Baffin Bay Baffin Baie de Baffin ice pack Phytoplankton Sea ice Southern Ocean |
op_source |
https://theses.hal.science/tel-03137420 Océanographie. Aix Marseille Université, 2021. Français. ⟨NNT : ⟩ |
op_relation |
tel-03137420 https://theses.hal.science/tel-03137420 https://theses.hal.science/tel-03137420/document https://theses.hal.science/tel-03137420/file/These_LAFOND.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1786827886177550336 |