Search

Your search keyword '"Vivien Hulot"' showing total 6 results
Start Over Author "Vivien Hulot"
6 results on '"Vivien Hulot"'

1. Impact of an exceptional winter flood on benthic oxygen and nutrient fluxes in a temperate macrotidal estuary: Potential consequences on summer deoxygenation

Author

Vivien Hulot, Edouard Metzger, Aubin Thibault de Chanvalon, Aurelia Mouret, Sabine Schmidt, Bruno Deflandre, Sylvain Rigaud, Eric Beneteau, Nicolas Savoye, Philippe Souchu, Yoann Le Merrer, and Grégoire M. Maillet

Subjects
estuary, water sediment exchanges, hypoxia, oxides-phosphorus interactions, flood, Science, General. Including nature conservation, geographical distribution, QH1-199.5
Abstract

Despite 20 years of control on eutrophication, episodes of summer hypoxia still occur in the Loire estuary, impacting water quality and posing a key scientific and management challenge. This work aimed to quantify the contribution of the benthic compartment to hypoxia in the Loire estuary by direct measurement of water–sediment fluxes and an in-depth understanding of the seasonal variations of oxides and phosphorus stocks. During the summer’s low-discharge period, results show that the iron oxide-rich deposit is stable under hypoxic conditions, limiting the release of dissolved phosphorus into the overlying water column. The high nitrate content of the water column appears to be an important oxidizer of iron during hypoxic periods, limiting dissolved phosphorus leakage and aggravation of hypoxia. During the exceptional winter flood, significant sediment erosion associated with bubbling phenomena (attributed to methane efflux) created severe fractures in the sediment and stimulated water–sediment exchange. During the following months, these fractures were progressively filled, which decreased the intensity of benthic fluxes. However, due to the high residence time in the water during the summer period, a simple model demonstrated that benthic contributions were sufficient to directly (by direct oxygen consumption) or indirectly (by promoting ammonia oxidation) affect the oxygen stock in the water column during the low-discharge period. Our study demonstrates the importance of the benthic compartment in the occurrence of hypoxia and the obvious lack of knowledge to illustrate and model the biogeochemical functioning of the estuary.

Published
2023
Full Text
View/download PDF

2. Early diagenetic processes in an eutrophic estuarine system: indices of sediment contribution to summer hypoxia of the Loire?

Author

Grégoire Maillet, Sabine Schmidt, Bruno Deflandre, Aurélia Mouret, Eric Bénéteau, Sophie Sanchez, Edouard Metzger, Sylvain Rigaud, Hervé Derriennic, Vivien Hulot, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
geography, geography.geographical_feature_category, Oceanography, 13. Climate action, [SDE]Environmental Sciences, Sediment, Hypoxia (environmental), Environmental science, Estuary, Eutrophication, ComputingMilieux_MISCELLANEOUS, 6. Clean water, Diagenesis
Abstract

International audience

Published
2021

3. Population dynamics of modern planktonic foraminifera in the western Barents Sea

Author

Julie Meilland, Hélène Howa, Vivien Hulot, Isaline Demangel, Joëlle Salaün, and Thierry Garlan

Subjects
0303 health sciences, 03 medical and health sciences, 0302 clinical medicine, 14. Life underwater, 030217 neurology & neurosurgery, 030304 developmental biology
Abstract

This study reports on diversity and distribution of planktonic foraminifera (PF) in the Barents Sea Opening (BSO). Populations of PF living in late summer (collected by means of stratified plankton tows) and recently deposited individuals (sampled by interface corer) were compared. High abundances reaching up to 400 ind.m-3 in tow samples and 8000 ind.m-3 in surface sediments were recorded in the centre of the studied area while low abundances were observed in coastal areas, likely due to continental influences. The living and core-top assemblages are mainly composed of the same four species Neogloboquadrina pachyderma, Neogloboquadrina incompta, Turborotalita quinqueloba and Globigerinita uvula. The two species G. uvula and T. quinqueloba dominate the upper water column, whereas surface sediment assemblages display particularly high concentrations of N. pachyderma. The unusual dominance of G. uvula in the water sample assemblages compared to its low proportion in surface sediments might be the signature of (1) a seasonal signal due to summer phytoplankton composition changes at the BSO, linked to the increase in summer temperature at the study site, and/or (2) a signal of a larger timescale and wider geographical reach phenomenon reflecting poleward temperate/subpolar species migration and consecutive foraminiferal assemblage diversification at high latitudes due to global change. Protein concentrations were measured on single specimens and used as a proxy of individual carbon biomass. Specimens of all species show the same trend, a northward decrease in their size-normalized-protein concentration. This suggests that foraminiferal biomass is potentially controlled by different constituents of their organelles (e.g. lipids). The coupling of data from plankton tows, protein measurements and surface sediments allows us to hypothesize that PF dynamics (seasonality and distribution) are decoupled from their metabolism.

Published
2020

4. Shellfish culture: a complex driver of planktonic communities

Author

Denis Saulnier, Céline Lafabrie, Nabila Gaertner-Mazouni, and Vivien Hulot

Subjects
0106 biological sciences, Disturbance (geology), Ecology, business.industry, 010604 marine biology & hydrobiology, Ecology (disciplines), 04 agricultural and veterinary sciences, Management, Monitoring, Policy and Law, Aquatic Science, Plankton, 01 natural sciences, Aquaculture, 040102 fisheries, 0401 agriculture, forestry, and fisheries, Environmental science, business, Shellfish
Published
2018

5. A survey of the summer coccolithophore community in the western Barents Sea

Author

Ludovic Devaux, Thierry Garlan, Hélène Howa, Vivien Hulot, Vincent Hanquiez, Jacques Giraudeau, Bio-Indicateurs Actuels et Fossiles (BIAF), Université d'Angers (UA), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Energy Efficient Computing ArchItectures with Embedded Reconfigurable Resources (CAIRN), Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-ARCHITECTURE (IRISA-D3), Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Télécom Bretagne-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Établissement principal du Service hydrographique et océanographique de la Marine (EPSHOM), EPSHOM, UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), CentraleSupélec-Télécom Bretagne-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National de Recherche en Informatique et en Automatique (Inria)-École normale supérieure - Rennes (ENS Rennes)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-CentraleSupélec-Télécom Bretagne-Université de Rennes 1 (UR1), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-École normale supérieure - Rennes (ENS Rennes)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)

Subjects
0106 biological sciences, Water mass, 010504 meteorology & atmospheric sciences, Coccolithophore, [SDV]Life Sciences [q-bio], Population, Aquatic Science, Oceanography, 01 natural sciences, Coccolith, Water column, Summer phytoplankton community, Coccolith calcite, Coccolithophores, Summer phytoplankton community, Western Barents Sea, Coccolithophores, Photic zone, 14. Life underwater, education, Ecology, Evolution, Behavior and Systematics, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Emiliania huxleyi, Polar front, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, education.field_of_study, biology, Western Barents Sea, 010604 marine biology & hydrobiology, Coccolith calcite, biology.organism_classification, 13. Climate action, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Geology
Abstract

International audience; The Barents Sea is particularly vulnerable to large-scale hydro-climatic changes associated with the polar amplification of climate change. Key oceanographical variables in this region are the seasonal development of sea-ice and the location and strength of physico-chemical gradients in the surface and subsurface water layers induced by the convergence of Arctic- and Atlantic-derived water masses. Remote sensing imagery have highlighted the increasing success of calcifying haptophytes (coccolithophores) in the summer phytoplankton production of the Barents Sea over the last 20years, as a response to an overall larger contribution of Atlantic waters to surface and sub-surface waters, as well as to enhanced sea-ice melt-induced summer stratification of the photic layer.The present study provides a first thorough description of coccolithophore standing stocks and diversity over the shelf and slope of the western Barents Sea from two sets of surface and water column samples collected during August–September 2014 from northern Norway to southern Svalbard. The abundance and composition of coccolithophore cells and skeletal remains (coccoliths) are discussed in view of the physical–chemical–biological status of the surface waters and water column based on in-situ (temperature, salinity, fluorescence) and shore-based (microscope enumerations, chemotaxonomy) measurements, as well as satellite-derived data (Chl a and particulate inorganic carbon contents).The coccolithophore population is characterized by a low species diversity and the overwhelming dominance of Emiliania huxleyi. Coccolithophores are abundant both within the well stratified, Norwegian coastal water — influenced shallow mixed layer off northern Norway, as well as within well-mixed cool Atlantic water in close vicinity of the Polar Front. Bloom concentrations with standing stocks larger than 4million cells/l are recorded in the latter area north of 75°N. Our limited set of chemotaxonomic data suggests that coccolithophores contribute substantially (ca. 20% of the total Chl a) to the summer phytoplankton community which is made essentially of small-sized algal groups. Excluding the bloom area, coccolith calcite accounts for an average of 20% to the bulk particulate inorganic carbon content in the surface waters, and explains to some extent the satellite-derived spatial distribution of this parameter. Deep water living coccolithophore species thriving below the pycnocline as well as populations present in well-mixed cool Atlantic water are rapidly transferred to depth in the form of intact coccospheres down to at least 200m. High amplitude internal waves which, according to our observations, affect a wide range of water depth up to the lower photic zone, might strengthen the vertical transfer of this sinking population.

Published
2016

6. Is the meiofauna a good indicator for climate change and anthropogenic impacts?

Author

Quentin Morel, Viatcheslav N. Ivanenko, Ludovic Hermabessiere, Jozée Sarrazin, Morgan Danielo, Roxanne Langonne-Augen, Diego Fontaneto, Ann Vanreusel, Daniela Zeppilli, Gwendoline Traisnel, Christophe Fontanier, Andrew J. Gooday, Vivien Hulot, David Fernandes, Dendy Mahabror, Alexandre Arvigo, Pedro Martínez Arbizu, Noemie Allio, Daniel Leduc, Tristan James, Marianna Mea, Mariam Weyand, Sarah Séité, Martin V. Sørensen, Laura Raimondeau, Reinhardt Møbjerg Kristensen, Tangi Le Bot, Raphaelle Fumeron, Kevin Urvoy, Valentin Foulon, Thomas Van Der Stegen, Thomas Andro, Jean-Xavier Castrec, Julien Thébault, Antoine Rio-Cabello, Etienne Pouplard, Marc Long, Michael Pantalos, IFREMER- Département Etude des Ecosystèmes Profonds (DEEP/LEP), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), National Institute of Water and Atmospheric Research [Wellington] (NIWA), CNR Institute of Ecosystem Study (ISE), Consiglio Nazionale delle Ricerche (CNR), Bio-Indicateurs Actuels et Fossiles (BIAF), Université d'Angers (UA), Unité de recherche Géosciences Marines (Ifremer) (GM), National Oceanography Centre [Southampton] (NOC), University of Southampton, Natural History Museum of Denmark, Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Lomonosov Moscow State University (MSU), Universiteit Gent = Ghent University [Belgium] (UGENT), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), and ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010)

Subjects
0106 biological sciences, [SDV]Life Sciences [q-bio], Meiobenthos, Meiofauna, GULF-OF-MEXICO, CLIPPERTON FRACTURE-ZONE, Biodiversity, Climate change, OXYGEN MINIMUM ZONE, Aquatic Science, Oceanography, 010603 evolutionary biology, 01 natural sciences, MANGROVE RHIZOPHORA-MANGLE, Anthropogenic impacts, SEAGRASS POSIDONIA-OCEANICA, SEWAGE-TREATMENT PLANTS, Ecosystem, 14. Life underwater, Taxonomic rank, Ecology, Evolution, Behavior and Systematics, SEA BENTHIC FORAMINIFERA, Ecology, ACL, 010604 marine biology & hydrobiology, Biology and Life Sciences, Global change, Natural observations and experimental studies, EASTERN TROPIC PACIFIC, CENTRAL INDIAN-OCEAN, Taxon, Geography, 13. Climate action, Benthic zone, Biomonitoring, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, NEMATODE-COPEPOD RATIO
Abstract

International audience; Our planet is changing, and one of the most pressing challenges facing the scientific community revolves around understanding how ecological communities respond to global changes. From coastal to deep-sea ecosystems, ecologists are exploring new areas of research to find model organisms that help predict the future of life on our planet. Among the different categories of organisms, meiofauna offer several advantages for the study of marine benthic ecosystems. This paper reviews the advances in the study of meiofauna with regard to climate change and anthropogenic impacts. Four taxonomic groups are valuable for predicting global changes: foraminifers (especially calcareous forms), nematodes, copepods and ostracods. Environmental variables are fundamental in the interpretation of meiofaunal patterns and multistressor experiments are more informative than single stressor ones, revealing complex ecological and biological interactions. Global change has a general negative effect on meiofauna, with important consequences on benthic food webs. However, some meiofaunal species can be favoured by the extreme conditions induced by global change, as they can exhibit remarkable physiological adaptations. This review highlights the need to incorporate studies on taxonomy, genetics and function of meiofaunal taxa into global change impact research.

Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results