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89 results on '"Ridame, Céline"'

1. Impact of Atmospheric Deposition on Marine Chemistry and Biogeochemistry

Author: Guieu, Cécile, Ridame, Céline, Dulac, François, editor, Sauvage, Stéphane, editor, and Hamonou, Eric, editor
Published: 2022
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2. A synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2022: the SNAPO-CO2-v1 dataset

Author: Metzl, Nicolas, primary, Fin, Jonathan, additional, Lo Monaco, Claire, additional, Mignon, Claude, additional, Alliouane, Samir, additional, Antoine, David, additional, Bourdin, Guillaume, additional, Boutin, Jacqueline, additional, Bozec, Yann, additional, Conan, Pascal, additional, Coppola, Laurent, additional, Diaz, Frédéric, additional, Douville, Eric, additional, Durrieu de Madron, Xavier, additional, Gattuso, Jean-Pierre, additional, Gazeau, Frédéric, additional, Golbol, Melek, additional, Lansard, Bruno, additional, Lefèvre, Dominique, additional, Lefèvre, Nathalie, additional, Lombard, Fabien, additional, Louanchi, Férial, additional, Merlivat, Liliane, additional, Olivier, Léa, additional, Petrenko, Anne, additional, Petton, Sébastien, additional, Pujo-Pay, Mireille, additional, Rabouille, Christophe, additional, Reverdin, Gilles, additional, Ridame, Céline, additional, Tribollet, Aline, additional, Vellucci, Vincenzo, additional, Wagener, Thibaut, additional, and Wimart-Rousseau, Cathy, additional
Published: 2024
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3. Anthropogenic CO2, air–sea CO2 fluxes, and acidification in the Southern Ocean: results from a time-series analysis at station OISO-KERFIX (51° S–68° E).

Author: Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Reverdin, Gilles, Chau, Thi Tuyet Trang, Chevallier, Frédéric, and Gehlen, Marion
Subjects: OCEAN acidification, ATMOSPHERIC carbon dioxide, ARTIFICIAL neural networks, CARBON dioxide, ATMOSPHERIC boundary layer, SUMMER
Abstract: The temporal variation of the carbonate system, air–sea CO 2 fluxes, and pH is analyzed in the southern Indian Ocean, south of the polar front, based on in situ data obtained from 1985 to 2021 at a fixed station (50°40 ′ S–68°25 ′ E) and results from a neural network model that reconstructs the fugacity of CO 2 (fCO2) and fluxes at monthly scale. Anthropogenic CO 2 (C ant) is estimated in the water column and is detected down to the bottom (1600 m) in 1985, resulting in an aragonite saturation horizon at 600 m that migrated up to 400 m in 2021 due to the accumulation of C ant. At the subsurface, the trend of C ant is estimated at +0.53±0.01 µ mol kg -1 yr -1 with a detectable increase in the trend in recent years. At the surface during austral winter the oceanic fCO2 increased at a rate close to or slightly lower than in the atmosphere. To the contrary, in summer, we observed contrasting fCO2 and dissolved inorganic carbon (C T) trends depending on the decade and emphasizing the role of biological drivers on air–sea CO 2 fluxes and pH inter-annual variability. The regional air–sea CO 2 fluxes evolved from an annual source to the atmosphere of 0.8 molC m -2 yr -1 in 1985 to a sink of -0.5 molC m -2 yr -1 in 2020. Over 1985–2020, the annual pH trend in surface waters of -0.0165±0.0040 per decade was mainly controlled by the accumulation of anthropogenic CO 2 , but the summer pH trends were modulated by natural processes that reduced the acidification rate in the last decade. Using historical data from November 1962, we estimated the long-term trend for fCO2 , C T , and pH, confirming that the progressive acidification was driven by the atmospheric CO 2 increase. In 59 years this led to a diminution of 11 % for both aragonite and calcite saturation state. As atmospheric CO 2 is expected to increase in the future, the pH and carbonate saturation state will decrease at a faster rate than observed in recent years. A projection of future C T concentrations for a high emission scenario (SSP5-8.5) indicates that the surface pH in 2100 would decrease to 7.32 in winter. This is up to -0.86 lower than pre-industrial pH and -0.71 lower than pH observed in 2020. The aragonite undersaturation in surface waters would be reached as soon as 2050 (scenario SSP5-8.5) and 20 years later for a stabilization scenario (SSP2-4.5) with potential impacts on phytoplankton species and higher trophic levels in the rich ecosystems of the Kerguelen Islands area. [ABSTRACT FROM AUTHOR]
Published: 2024
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4. Supplementary material to "Anthropogenic CO2, air-sea CO2 fluxes and acidification in the Southern Ocean: results from a time-series analysis at station OISO-KERFIX (51°S-68°E)"

Author: Metzl, Nicolas, primary, Lo Monaco, Claire, additional, Leseurre, Coraline, additional, Ridame, Céline, additional, Reverdin, Gilles, additional, Chau, Thi Tuyet Trang, additional, Chevallier, Frédéric, additional, and Gehlen, Marion, additional
Published: 2023
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5. Anthropogenic CO2, air-sea CO2 fluxes and acidification in the Southern Ocean: results from a time-series analysis at station OISO-KERFIX (51°S-68°E)

Author: Metzl, Nicolas, primary, Lo Monaco, Claire, additional, Leseurre, Coraline, additional, Ridame, Céline, additional, Reverdin, Gilles, additional, Chau, Thi Tuyet Trang, additional, Chevallier, Frédéric, additional, and Gehlen, Marion, additional
Published: 2023
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6. Diazotrophy in the Indian Ocean: Current understanding and future perspectives

Author: Chowdhury, Subhadeep, primary, Raes, Eric, additional, Hörstmann, Cora, additional, Ahmed, Ayaz, additional, Ridame, Céline, additional, Metzl, Nicolas, additional, Bhavya, P S, additional, Sato, Takuya, additional, Shiozaki, Takuhei, additional, Bonnet, Sophie, additional, Löscher, Carolin R., additional, Singh, Arvind, additional, and Benavides, Mar, additional
Published: 2023
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7. A synthesis of SNAPO-CO2 ocean total alkalinity and total dissolved inorganic carbon measurements from 1993 to 2022

Author: Metzl, Nicolas, primary, Fin, Jonathan, additional, Lo Monaco, Claire, additional, Mignon, Claude, additional, Alliouane, Samir, additional, Antoine, David, additional, Bourdin, Guillaume, additional, Boutin, Jacqueline, additional, Bozec, Yann, additional, Conan, Pascal, additional, Coppola, Laurent, additional, Diaz, Frédéric, additional, Douville, Eric, additional, Durrieu de Madron, Xavier, additional, Gattuso, Jean-Pierre, additional, Gazeau, Frédéric, additional, Golbol, Melek, additional, Lansard, Bruno, additional, Lefèvre, Dominique, additional, Lefèvre, Nathalie, additional, Lombard, Fabien, additional, Louanchi, Férial, additional, Merlivat, Liliane, additional, Olivier, Léa, additional, Petrenko, Anne, additional, Petton, Sébastien, additional, Pujo-Pay, Mireille, additional, Rabouille, Christophe, additional, Reverdin, Gilles, additional, Ridame, Céline, additional, Tribollet, Aline, additional, Vellucci, Vincenzo, additional, Wagener, Thibaut, additional, and Wimart-Rousseau, Cathy, additional
Published: 2023
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8. Supplementary material to "A synthesis of SNAPO-CO2 ocean total alkalinity and total dissolved inorganic carbon measurements from 1993 to 2022"

Author: Metzl, Nicolas, primary, Fin, Jonathan, additional, Lo Monaco, Claire, additional, Mignon, Claude, additional, Alliouane, Samir, additional, Antoine, David, additional, Bourdin, Guillaume, additional, Boutin, Jacqueline, additional, Bozec, Yann, additional, Conan, Pascal, additional, Coppola, Laurent, additional, Diaz, Frédéric, additional, Douville, Eric, additional, Durrieu de Madron, Xavier, additional, Gattuso, Jean-Pierre, additional, Gazeau, Frédéric, additional, Golbol, Melek, additional, Lansard, Bruno, additional, Lefèvre, Dominique, additional, Lefèvre, Nathalie, additional, Lombard, Fabien, additional, Louanchi, Férial, additional, Merlivat, Liliane, additional, Olivier, Léa, additional, Petrenko, Anne, additional, Petton, Sébastien, additional, Pujo-Pay, Mireille, additional, Rabouille, Christophe, additional, Reverdin, Gilles, additional, Ridame, Céline, additional, Tribollet, Aline, additional, Vellucci, Vincenzo, additional, Wagener, Thibaut, additional, and Wimart-Rousseau, Cathy, additional
Published: 2023
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9. Saharan Input of Phosphate to the Oligotrophic Water of the Open Western Mediterranean Sea

Author: Ridame, Céline and Guieu, Cécile
Published: 2002

10. Anthropogenic CO2, air-sea CO2 fluxes and acidification in the Southern Ocean: results from a time-series analysis at station OISO-KERFIX (51°S-68°E).

Author: Metzl, Nicolas, Monaco, Claire Lo, Leseurre, Coraline, Ridame, Céline, Reverdin, Gilles, Thi Tuyet Trang Chau, Chevallier, Frédéric, and Gehlen, Marion
Subjects: OCEAN acidification, ATMOSPHERIC boundary layer, ARAGONITE, FOOD chains, OCEAN-atmosphere interaction
Abstract: The temporal variation of the carbonate system, air-sea CO2 fluxes and pH is analyzed in the Southern Indian Ocean, south of the Polar Front, based on in-situ data obtained from 1985 to 2021 at a fixed station (50°40'S-68°25'E) and results from a neural network model that reconstructs the fugacity of CO2 (fCO2) and fluxes at monthly scale. Anthropogenic CO2 (Cant) was estimated in the water column and detected down to the bottom (1600m) in 1985 resulting in an aragonite saturation horizon at 600m that migrated up to 400m in 2021 due to the accumulation of Cant. In subsurface, the trend of Cant is estimated at +0.53 (±0.01) µmol.kg-1.yr-1 with a detectable increase in recent years. At the surface during austral winter the oceanic fCO2 increased at a rate close or slightly lower than in the atmosphere. To the contrary, in summer, we observed contrasting fCO2 and dissolved inorganic carbon (CT) trends depending on the decade and emphasizing the role of biological drivers on air-sea CO2 fluxes and pH inter-annual variability. The region moved from an annual source of 0.8 molC.m- 2.yr-1 in 1985 to a sink of -0.5 molC.m-2.yr-1 in 2020. In 1985-2020, the annual pH trend in surface of -0.0165 (± 0.0040).decade-1 was mainly controlled by anthropogenic CO2 but the trend was modulated by natural processes. Using historical data from November 1962 we estimated the long-term trend for fCO2, CT and pH confirming that the progressive acidification was driven by atmospheric CO2 increase. In 59 years this leads to a diminution of 11% for both aragonite and calcite saturation state. As atmospheric CO2 will desperately continue rising in the future, the pH and carbonate saturation state will decrease at a faster rate than observed in recent years. A projection of future CT concentrations for a high emission scenario (SSP5-8.5) indicates that the surface pH in 2100 would decrease to 7.32 in winter. This is up to -0.86 lower than pre-industrial pH and -0.71 lower than pH observed in 2020. The aragonite under-saturation in surface waters would be reached as soon as 2050 (scenario SSP5-8.5) and 20 years later for a stabilization scenario (SSP2-4.5) with potential impacts on phytoplankton species and higher trophic levels in the rich ecosystems of the Kerguelen Island area. [ABSTRACT FROM AUTHOR]
Published: 2023
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11. Spatial variability of the primary production and structure of the phytoplankton community in the South Indian Ocean.

Author: Deteix, Valentin, primary, Ridame, Céline, additional, Tribollet, Aline, additional, Dimier, Céline, additional, Thyssen, Melilotus, additional, and Gest, Léa, additional
Published: 2023
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12. Phytoplanktonic response to simulated volcanic and desert dust deposition events in the South Indian and Southern Oceans

Author: Geisen, Carla, primary, Ridame, Céline, additional, Journet, Emilie, additional, Delmelle, Pierre, additional, Marie, Dominique, additional, Lo Monaco, Claire, additional, Metzl, Nicolas, additional, Ammar, Rawaa, additional, Kombo, Joelle, additional, and Cardinal, Damien, additional
Published: 2022
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13. Increased intracellular concentrations of DMSP and DMSO in iron-limited oceanic phytoplankton Thalassiosira oceanica and Trichodesmium erythraeum

Author: Bucciarelli, Eva, Ridame, Céline, Sunda, William G., Dimier-Hugueney, Céline, Cheize, Marie, and Belviso, Sauveur
Published: 2013

14. The impact of the South-East Madagascar Bloom on the oceanic CO2 sink

Author: Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Fin, Jonathan, Mignon, Claude, Gehlen, Marion, Chau, Thi Tuyet Trang, Cycles biogéochimiques marins : processus et perturbations (CYBIOM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (SNO OISO, SOERE/Great-Gases, LEFE ITALIANO, Sorbonne Université (SNO OISO), and European Project: 633211,H2020,H2020-BG-2014-2,AtlantOS(2015)
Subjects: TheoryofComputation_MATHEMATICALLOGICANDFORMALLANGUAGES, [SDE.MCG]Environmental Sciences/Global Changes
Abstract: We described new sea surface CO2 observations in the south-western Indian Ocean obtained in January 2020 when a strong bloom event occurred south-east of Madagascar and extended eastward in the oligotrophic Indian Ocean subtropical domain. Compared to previous years (1991–2019) we observed very low fCO2 and dissolved inorganic carbon concentrations (CT) in austral summer 2020, indicative of a biologically driven process. In the bloom, the anomaly of fCO2 and CT reached respectively −33 µatm and −42 µmol kg−1, whereas no change is observed for alkalinity (AT). In January 2020 we estimated a local maximum of air–sea CO2 flux at 27∘ S of −6.9 mmol m−2 d−1 (ocean sink) and −4.3 mmol m−2 d−1 when averaging the flux in the band 26–30∘ S. In the domain 25–30∘ S, 50–60∘ E we estimated that the bloom led to a regional carbon uptake of about −1 TgC per month in January 2020, whereas this region was previously recognized as an ocean CO2 source or near equilibrium during this season. Using a neural network approach that reconstructs the monthly fCO2 fields, we estimated that when the bloom was at peak in December 2019 the CO2 sink reached −3.1 (±1.0) mmol m−2 d−1 in the band 25–30∘ S; i.e. the model captured the impact of the bloom. Integrated in the domain restricted to 25–30∘ S, 50–60∘ E, the region was a CO2 sink in December 2019 of −0.8 TgC per month compared to a CO2 source of +0.12 (±0.10) TgC per month in December when averaged over the period 1996–2018. Consequently in 2019 this region was a stronger CO2 annual sink of −8.8 TgC yr−1 compared to −7.0 (±0.5) TgC yr−1 averaged over 1996–2018. In austral summer 2019–2020, the bloom was likely controlled by a relatively deep mixed-layer depth during the preceding winter (July–September 2019) that would supply macro- and/or micro-nutrients such as iron to the surface layer to promote the bloom that started in November 2019 in two large rings in the Madagascar Basin. Based on measurements in January 2020, we observed relatively high N2 fixation rates (up to 18 nmol N L−1 d−1), suggesting that diazotrophs could play a role in the bloom in the nutrient-depleted waters. The bloom event in austral summer 2020, along with the new carbonate system observations, represents a benchmark case for complex biogeochemical model sensitivity studies (including the N2 fixation process and iron supplies) for a better understanding of the origin and termination of this still “mysterious” sporadic bloom and its impact on ocean carbon uptake in the future.
Published: 2022

15. Diazotrophic bacteria respond to Saharan dust additions

Author: Langlois, Rebecca J., Mills, Matthew M., Ridame, Celine, Croot, Peter, and LaRoche, Julie
Published: 2012

16. Impact of dust addition on the microbial food web under present and future conditions of pH and temperature

Author: Dinasquet, Julie, primary, Bigeard, Estelle, additional, Gazeau, Frédéric, additional, Azam, Farooq, additional, Guieu, Cécile, additional, Marañón, Emilio, additional, Ridame, Céline, additional, Van Wambeke, France, additional, Obernosterer, Ingrid, additional, and Baudoux, Anne-Claire, additional
Published: 2022
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17. N<sub>2</sub> fixation in the Mediterranean Sea related to the composition of the diazotrophic community and impact of dust under present and future environmental conditions

Author: Ridame, Céline, primary, Dinasquet, Julie, additional, Hallstrøm, Søren, additional, Bigeard, Estelle, additional, Riemann, Lasse, additional, Van Wambeke, France, additional, Bressac, Matthieu, additional, Pulido-Villena, Elvira, additional, Taillandier, Vincent, additional, Gazeau, Fréderic, additional, Tovar-Sanchez, Antonio, additional, Baudoux, Anne-Claire, additional, and Guieu, Cécile, additional
Published: 2022
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18. Nutrient Limitation of Picophytoplankton Photosynthesis and Growth in the Tropical North Atlantic

Author: Davey, Margaret, Tarran, Glen A., Mills, Matthew M., Ridame, Celine, Geider, Richard J., and LaRoche, Julie
Published: 2008

19. Subsurface iron accumulation and rapid aluminum removal in the Mediterranean following African dust deposition

Author: Bressac, Matthieu, primary, Wagener, Thibaut, additional, Leblond, Nathalie, additional, Tovar-Sánchez, Antonio, additional, Ridame, Céline, additional, Taillandier, Vincent, additional, Albani, Samuel, additional, Guasco, Sophie, additional, Dufour, Aurélie, additional, Jacquet, Stéphanie H. M., additional, Dulac, François, additional, Desboeufs, Karine, additional, and Guieu, Cécile, additional
Published: 2021
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20. Supplementary material to "The impact of the South-East Madagascar bloom on the oceanic CO<sub>2</sub> sink"

Author: Metzl, Nicolas, primary, Lo Monaco, Claire, additional, Leseurre, Coraline, additional, Ridame, Céline, additional, Fin, Jonathan, additional, Mignon, Claude, additional, Gehlen, Marion, additional, and Chau, Thi Tuyet Trang, additional
Published: 2021
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21. The impact of the South-East Madagascar bloom on the oceanic CO2 sink

Author: Metzl, Nicolas, primary, Lo Monaco, Claire, additional, Leseurre, Coraline, additional, Ridame, Céline, additional, Fin, Jonathan, additional, Mignon, Claude, additional, Gehlen, Marion, additional, and Chau, Thi Tuyet Trang, additional
Published: 2021
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22. Influence of atmospheric deposition on biogeochemical cycles in an oligotrophic ocean system

Author: Van Wambeke, France, primary, Taillandier, Vincent, additional, Desboeufs, Karine, additional, Pulido-Villena, Elvira, additional, Dinasquet, Julie, additional, Engel, Anja, additional, Marañón, Emilio, additional, Ridame, Céline, additional, and Guieu, Cécile, additional
Published: 2021
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23. Impact of dust addition on Mediterranean plankton communities under present and future conditions of pH and temperature: an experimental overview

Author: Gazeau, Frédéric, Ridame, Céline, Van Wambeke, France, Alliouane, Samir, Stolpe, Christian, Irisson, Jean-Olivier, Marro, Sophie, Grisoni, Jean-Michel, De Liège, Guillaume, Nunige, Sandra, Djaoudi, Kahina, Pulido-Villena, Elvira, Dinasquet, Julie, Obernosterer, Ingrid, Catala, Philippe, Guieu, Cécile, Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Cycles biogéochimiques marins : processus et perturbations (CYBIOM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), 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), Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Scripps Institution of Oceanography (SIO - UC San Diego), University of California [San Diego] (UC San Diego), University of California (UC)-University of California (UC), Laboratoire d'Océanographie Microbienne (LOMIC), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Observatoire océanologique de Banyuls (OOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Scripps Institution of Oceanography (SIO), University of California-University of California, and Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire océanologique de Banyuls (OOB)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDE]Environmental Sciences
Abstract: In low-nutrient low-chlorophyll areas, such as the Mediterranean Sea, atmospheric fluxes represent a considerable external source of nutrients likely supporting primary production, especially during periods of stratification. These areas are expected to expand in the future due to lower nutrient supply from sub-surface waters caused by climate-driven enhanced stratification, likely further increasing the role of atmospheric deposition as a source of new nutrients to surface waters. Whether plankton communities will react differently to dust deposition in a warmer and acidified environment remains; however, an open question. The potential impact of dust deposition both in present and future climate conditions was investigated in three perturbation experiments in the open Mediterranean Sea. Climate reactors (300 L) were filled with surface water collected in the Tyrrhenian Sea, Ionian Sea and in the Algerian basin during a cruise conducted in the frame of the PEACETIME project in May–June 2017. The experiments comprised two unmodified control tanks, two tanks enriched with a Saharan dust analogue and two tanks enriched with the dust analogue and maintained under warmer (+3 ∘C) and acidified (−0.3 pH unit) conditions. Samples for the analysis of an extensive number of biogeochemical parameters and processes were taken over the duration (3–4 d) of the experiments. Dust addition led to a rapid release of nitrate and phosphate, however, nitrate inputs were much higher than phosphate. Our results showed that the impacts of Saharan dust deposition in three different basins of the open northwestern Mediterranean Sea are at least as strong as those observed previously, all performed in coastal waters. The effects of dust deposition on biological stocks were different for the three investigated stations and could not be attributed to differences in their degree of oligotrophy but rather to the initial metabolic state of the community. Ocean acidification and warming did not drastically modify the composition of the autotrophic assemblage, with all groups positively impacted by warming and acidification. Although autotrophic biomass was more positively impacted than heterotrophic biomass under future environmental conditions, a stronger impact of warming and acidification on mineralization processes suggests a decreased capacity of Mediterranean surface plankton communities to sequester atmospheric CO2 following the deposition of atmospheric particles.
Published: 2021

24. N2 fixation in the Mediterranean Sea related to the composition of the diazotrophic community, and impact of dust under present and future environmental conditions

Author: Ridame, Céline, Dinasquet, Julie, Hallstrøm, Søren, Bigeard, Estelle, Riemann, Lasse, van Wambeke, France, Bressac, Matthieu, Pulido-Villena, Elvira, Taillandier, Vincent, Gazeau, Frédéric, Tovar-Sánchez, Antonio, Baudoux, Anne-Claire, Guieu, Cécile, Cycles biogéochimiques marins : processus et perturbations (CYBIOM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Scripps Institution of Oceanography (SIO - UC San Diego), University of California [San Diego] (UC San Diego), University of California (UC)-University of California (UC), Laboratoire d'Océanographie Microbienne (LOMIC), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Observatoire océanologique de Banyuls (OOB), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Copenhagen = Københavns Universitet (UCPH), Adaptation et diversité en milieu marin (ADMM), Institut national des sciences de l'Univers (INSU - CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), 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), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Institute of Marine Sciences of Andalusia (ICMAN), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Sorbonne Université (SU), Centre National de la Recherche Scientifique (CNRS), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Scripps Institution of Oceanography (SIO), University of California-University of California, Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire océanologique de Banyuls (OOB), University of Copenhagen = Københavns Universitet (KU), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), PEACETIME project (http://peacetime-project.org), GEOTRACES, Centre National de la Recherche Scientifique (France), European Commission, Danish Council for Independent Research, and Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract: N2 fixation rates were measured in the 0-1000ĝ€¯m layer at 13 stations located in the open western and central Mediterranean Sea (MS) during the PEACETIME cruise (late spring 2017). While the spatial variability in N2 fixation was not related to Fe, P nor N stocks, the surface composition of the diazotrophic community indicated a strong longitudinal gradient increasing eastward for the relative abundance of non-cyanobacterial diazotrophs (NCDs) (mainly 3-Proteobacteria) and conversely decreasing eastward for photo-heterotrophic group A (UCYN-A) (mainly UCYN-A1 and UCYN-A3), as did N2 fixation rates. UCYN-A4 and UCYN-A3 were identified for the first time in the MS. The westernmost station influenced by Atlantic waters and characterized by highest stocks of N and P displayed a patchy distribution of diazotrophic activity with an exceptionally high rate in the euphotic layer of 72.1ĝ€¯nmolNL-1d-1, which could support up to 19ĝ€¯% of primary production. At this station at 1ĝ€¯%PAR (photosynthetically available radiation) depth, UCYN-A4 represented up to 94ĝ€¯% of the diazotrophic community. These in situ observations of greater relative abundance of UCYN-A at stations with higher nutrient concentrations and dominance of NCDs at more oligotrophic stations suggest that nutrient conditions-even in the nanomolar range-may determine the composition of diazotrophic communities and in turn N2 fixation rates. The impact of Saharan dust deposition on N2 fixation and diazotrophic communities was also investigated, under present and future projected conditions of temperature and pH during short-Term (3-4ĝ€¯d) experiments at three stations. New nutrients from simulated dust deposition triggered a significant stimulation of N2 fixation (from 41ĝ€¯% to 565ĝ€¯%). The strongest increase in N2 fixation was observed at the stations dominated by NCDs and did not lead on this short timescale to changes in the diazotrophic community composition. Under projected future conditions, N2 fixation was either increased or unchanged; in that later case this was probably due to a too-low nutrient bioavailability or an increased grazing pressure. The future warming and acidification likely benefited NCDs (Pseudomonas) and UCYN-A2, while disadvantaged UCYN-A3 without knowing which effect (alone or in combination) is the driver, especially since we do not know the temperature optima of these species not yet cultivated as well as the effect of acidification., This study is a contribution to the PEACETIME project (http://peacetime-project.org, last access: 17 January 2022), a joint initiative of the MERMEX and ChArMEx components supported by the CNRS-INSU, IFREMER, CEA and Météo-France as part of the program MISTRALS coordinated by the INSU. PEACETIME was endorsed as a process study by GEOTRACES. Julie Dinasquet was funded by a Marie Curie Actions International Outgoing Fellowship (PIOF-GA-2013-629378). Søren Hallstrøm and Lasse Riemann were funded by grant 6108-00013 from the Danish Council for Independent Research.
Published: 2021

25. Contrasted release of insoluble elements (Fe, Al, rare earth elements, Th, Pa) after dust deposition in seawater: a tank experiment approach

Author: Roy-Barman, Matthieu, Foliot, Lorna, Douville, Eric, Leblond, Nathalie, Gazeau, Frédéric, Bressac, Matthieu, Wagener, Thibaut, Ridame, Céline, Desboeufs, Karine, Guieu, Cécile, Géochimie Des Impacts (GEDI), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Géochrononologie Traceurs Archéométrie (GEOTRAC), Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of Tasmania [Hobart, Australia] (UTAS), 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), Cycles biogéochimiques marins : processus et perturbations (CYBIOM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Toulon (UTLN), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: [SDE]Environmental Sciences
Abstract: Lithogenic elements such as aluminum (Al), iron (Fe), rare earth elements (REEs), thorium (232Th and 230Th, given as Th) and protactinium (Pa) are often assumed to be insoluble. In this study, their dissolution from Saharan dust reaching Mediterranean seawater was studied through tank experiments over 3 to 4 d under controlled conditions including controls without dust addition as well as dust seeding under present and future climate conditions (+3 ∘C and −0.3 pH). Unfiltered surface seawater from three oligotrophic regions (Tyrrhenian Sea, Ionian Sea and Algerian Basin) were used. The maximum dissolution was low for all seeding experiments: less than 0.3 % for Fe, 1 % for 232Th and Al, about 2 %–5 % for REEs and less than 6 % for Pa. Different behaviors were observed: dissolved Al increased until the end of the experiments, Fe did not dissolve significantly, and Th and light REEs were scavenged back on particles after a fast initial release. The constant 230Th/232Th ratio during the scavenging phase suggests that there is little or no further dissolution after the initial Th release. Quite unexpectedly, comparison of present and future conditions indicates that changes in temperature and/or pH influence the release of Th and REEs in seawater, leading to lower Th release and a higher light REE release under increased greenhouse conditions.
Published: 2021

26. Supplementary material to "N2 fixation in the Mediterranean Sea related to the composition of the diazotrophic community, and impact of dust under present and future environmental conditions"

Author: Ridame, Céline, primary, Dinasquet, Julie, additional, Hallstrøm, Søren, additional, Bigeard, Estelle, additional, Riemann, Lasse, additional, Van Wambeke, France, additional, Bressac, Matthieu, additional, Pulido-Villena, Elvira, additional, Taillandier, Vincent, additional, Gazeau, Frederic, additional, Tover-Sanchez, Antonio, additional, Baudoux, Anne-Claire, additional, and Guieu, Cécile, additional
Published: 2021
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27. N2 fixation in the Mediterranean Sea related to the composition of the diazotrophic community, and impact of dust under present and future environmental conditions

Author: Ridame, Céline, primary, Dinasquet, Julie, additional, Hallstrøm, Søren, additional, Bigeard, Estelle, additional, Riemann, Lasse, additional, Van Wambeke, France, additional, Bressac, Matthieu, additional, Pulido-Villena, Elvira, additional, Taillandier, Vincent, additional, Gazeau, Frederic, additional, Tover-Sanchez, Antonio, additional, Baudoux, Anne-Claire, additional, and Guieu, Cécile, additional
Published: 2021
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28. Supplementary material to "Impact of dust addition on the microbial food web under present and future conditions of pH and temperature"

Author: Dinasquet, Julie, primary, Bigeard, Estelle, additional, Gazeau, Frédéric, additional, Azam, Farooq, additional, Guieu, Cécile, additional, Marañón, Emilio, additional, Ridame, Céline, additional, Van Wambeke, France, additional, Obernosterer, Ingrid, additional, and Baudoux, Anne-Claire, additional
Published: 2021
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29. Impact of dust addition on the microbial food web under present and future conditions of pH and temperature

Author: Dinasquet, Julie, primary, Bigeard, Estelle, additional, Gazeau, Frédéric, additional, Azam, Farooq, additional, Guieu, Cécile, additional, Marañón, Emilio, additional, Ridame, Céline, additional, Van Wambeke, France, additional, Obernosterer, Ingrid, additional, and Baudoux, Anne-Claire, additional
Published: 2021
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30. Supplementary material to "Subsurface iron accumulation and rapid aluminium removal in the Mediterranean following African dust deposition"

Author: Bressac, Matthieu, primary, Wagener, Thibaut, additional, Leblond, Nathalie, additional, Tovar-Sánchez, Antonio, additional, Ridame, Céline, additional, Albani, Samuel, additional, Guasco, Sophie, additional, Dufour, Aurélie, additional, Jacquet, Stéphanie, additional, Dulac, François, additional, Desboeufs, Karine, additional, and Guieu, Cécile, additional
Published: 2021
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31. Supplementary material to "Influence of atmospheric deposition on biogeochemical cycles in an oligotrophic ocean system"

Author: Van Wambeke, France, primary, Taillandier, Vincent, additional, Deboeufs, Karine, additional, Pulido-Villena, Elvira, additional, Dinasquet, Julie, additional, Engel, Anja, additional, Marañón, Emilio, additional, Ridame, Céline, additional, and Guieu, Cécile, additional
Published: 2020
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32. Influence of atmospheric deposition on biogeochemical cycles in an oligotrophic ocean system

Author: Van Wambeke, France, primary, Taillandier, Vincent, additional, Deboeufs, Karine, additional, Pulido-Villena, Elvira, additional, Dinasquet, Julie, additional, Engel, Anja, additional, Marañón, Emilio, additional, Ridame, Céline, additional, and Guieu, Cécile, additional
Published: 2020
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33. Impact of dust enrichment on Mediterranean plankton communities under present and future conditions of pH and temperature: an experimental overview

Author: Gazeau, Frédéric, primary, Ridame, Céline, additional, Van Wambeke, France, additional, Alliouane, Samir, additional, Stolpe, Christian, additional, Irisson, Jean-Olivier, additional, Marro, Sophie, additional, Grisoni, Jean-Michel, additional, De Liège, Guillaume, additional, Nunige, Sandra, additional, Djaoudi, Kahina, additional, Pulido-Villena, Elvira, additional, Dinasquet, Julie, additional, Obernosterer, Ingrid, additional, Catala, Philippe, additional, and Guieu, Cécile, additional
Published: 2020
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34. Contrasted release of insoluble elements (Fe, Al, REE, Th, Pa) after dust deposition in seawater: a tank experiment approach

Author: Roy-Barman, Matthieu, primary, Folio, Lorna, additional, Douville, Eric, additional, Leblond, Nathalie, additional, Gazeau, Fréderic, additional, Bressac, Matthieu, additional, Wagener, Thibaut, additional, Ridame, Céline, additional, Desboeufs, Karine, additional, and Guieu, Cécile, additional
Published: 2020
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35. Supplementary material to "Contrasted release of insoluble elements (Fe, Al, REE, Th, Pa) after dust deposition in seawater: a tank experiment approach"

Author: Roy-Barman, Matthieu, primary, Folio, Lorna, additional, Douville, Eric, additional, Leblond, Nathalie, additional, Gazeau, Fréderic, additional, Bressac, Matthieu, additional, Wagener, Thibaut, additional, Ridame, Céline, additional, Desboeufs, Karine, additional, and Guieu, Cécile, additional
Published: 2020
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36. The impact of the South-East Madagascar bloom on the oceanic CO2 sink.

Author: Metzl, Nicolas, Lo Monaco, Claire, Leseurre, Coraline, Ridame, Céline, Fin, Jonathan, Mignon, Claude, Gehlen, Marion, and Thi Tuyet Trang Chau
Subjects: ATMOSPHERIC carbon dioxide, ANTS, CARBON dioxide in water, SEAWATER salinity, CARBON dioxide in seawater, ALGAL blooms, CALIBRATION gases
Abstract: We described new sea surface CO2 observations in the southwestern Indian Ocean obtained in January 2020 when a strong bloom event occurred south-east of Madagascar and extended eastward in the oligotrophic Indian Ocean subtropical domain. Compared to previous years (1991-2019) we observed very low fCO2 and dissolved inorganic carbon concentrations (CT) in austral summer 2020, indicative of a biologically driven process. In the bloom the anomaly of fCO2 and C[sub T] reached respectively -33 µatm and -42 µmol.kg-1 whereas no change is observed for alkalinity (AT). In January 2020 we estimated a local maximum of air-sea CO2 flux at 27°S of -6.9 mmol.m-2.d-1 (ocean sink) and -4.3 mmol.m[sup -2].d[sup -1] when averaging the flux in the band 26-30°S. In the domain 25-30°S/50-60°E we estimated that the bloom led to a regional carbon uptake of about -1 TgC.month-1 in January 2020 whereas this region was previously recognized as an ocean CO2 source or near equilibrium during this season. Using a neural network approach that reconstructs the monthly fCO2 fields we estimated that when the bloom was at peak in December 2019 the CO2 sink reached -3.1 (±1.0) mmol.m[sup -2].d[sup -1] in the band 25-30°S, i.e. the model captured the impact of the bloom. Integrated in the domain restricted to 25-30°S/50-60°E the region was a CO2 sink in December 2019 of -0.8 TgC.month[sup -1] compared to a CO2 source of +0.12 (± 0.10) TgC.month-1 in December when averaged over the period 1996-2018. Consequently in 2019 this region was a stronger CO2 annual sink of -8.8 TgC.yr-1 compared to -7.0 (±0.5) TgC.yr-1 averaged over 1996-2018. In austral summer 2019/2020, the bloom was likely controlled by relatively deep mixed-layer depth during preceding winter (July-September 2019) that would supply macro and/or micro-nutrients as iron to the surface layer to promote the bloom that started in November 2019 in two large rings in the Madagascar Basin. Based on measurements in January 2020, we observed relatively high N2 fixation rates (up to 18 nmol N.L-1.d-1) suggesting that diazotrophs could play a role on the bloom in the nutrient depleted waters. The bloom event in austral summer 2020, along with the new carbonate system observations, represents a benchmark case for complex biogeochemical model sensitivity studies (including N[sub 2]-fixation process and iron supplies) for a better understanding on the origin and termination of this still "mysterious" sporadic bloom and its impact on ocean carbon uptake in the future. [ABSTRACT FROM AUTHOR]
Published: 2021
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37. N2 fixation in the Mediterranean Sea related to the composition of the diazotrophic community, and impact of dust under present and future environmental conditions.

Author: Ridame, Céline, Dinasquet, Julie, Hallstrøm, Søren, Bigeard, Estelle, Riemann, Lasse, Van Wambeke, France, Bressac, Matthieu, Pulido-Villena, Elvira, Taillandier, Vincent, Gazeau, Frederic, Tovar-Sanchez, Antonio, Baudoux, Anne-Claire, and Guieu, Cécile
Subjects: NITROGEN fixation, DUST, CARBON fixation, HIGH density polyethylene, MINERAL dusts, DETECTION limit, NUCLEOTIDE sequencing
Abstract: N2 fixation rates were measured in the 0-1000 m layer at 13 stations located in the open western and central Mediterranean Sea (MS) during the PEACETIME cruise (late spring 2017). While the spatial variability of N2 fixation was not related to Fe, P nor N stocks, the surface composition of the diazotrophic community indicated a strong eastward increasing longitudinal gradient for the relative abundance of non-cyanobacterial diazotrophs (NCD) (mainly γ-Proteobacteria) and conversely eastward decreasing for UCYN-A (mainly -A1 and -A3) as did N2 fixation rates. UCYN-A4 and -A3 were identified for the first time in the MS. The westernmost station influenced by Atlantic waters, and characterized by highest stocks of N and P, displayed a patchy distribution of diazotrophic activity with an exceptionally high rate in the euphotic layer of 72.1 nmol N L-1 d-1, which could support up to 19 % of primary production. At this station at 1%PAR depth, UCYN-A4 represented up to 94 % of the diazotrophic community. These in situ observations of higher UCYN-A relative abundance in nutrient rich stations while NCD increased in the more oligotrophic stations, suggest that the nutrient conditions could determine the composition of the diazotrophic communities and in turn the N2 fixation rates. The impact of Saharan dust deposition on N2 fixation and diazotrophic communities was also investigated, under present and future projected conditions of temperature and pH during short term (3-4 days) experiments at three stations. New nutrients from simulated dust deposition triggered a significant stimulation of N2 fixation (from 41 % to 565 %). The strongest increase in N2 fixation was observed at the stations dominated by NCD and did not lead on this short time scale to change in the diazotrophic community composition. Under projected future conditions, N2 fixation was either exacerbated or unchanged; in that later case this was probably due to a too low nutrient bioavailability or an increased grazing pressure. The future warming and acidification likely benefited NCD (Pseudomonas) and UCYN-A2 while disadvantaged UCYN-A3 without knowing which effect (alone or in combination) is the driver, especially since we do not know the temperature optima of these species not yet cultivated as well as the effect of acidification. [ABSTRACT FROM AUTHOR]
Published: 2021
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38. Does phosphate adsorption onto Saharan dust explain the unusual N/P ratio in the Mediterranean Sea?

Author: Ridame, Céline, Moutin, Thierry, and Guieu, Cécile
Published: 2003
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39. Nutrients and carbon budgets for the Gulf of Lion during the Moogli cruises

Author: de Madron, Xavier Durrieu, Denis, Lionel, Diaz, Frédérique, Garcia, N, Guieu, Cécile, Grenz, Christian, Loÿe-Pilot, Marie-Dominique, Ludwig, Wolfgang, Moutin, Thierry, Raimbault, Patrick, and Ridame, Céline
Published: 2003
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40. Impact of dust addition on the microbial food web under present and future conditions of pH and temperature.

Author: Dinasquet, Julie, Bigeard, Estelle, Gazeau, Frédéric, Azam, Farooq, Guieu, Cécile, Marañón, Emilio, Ridame, Céline, Van Wambeke, France, Obernosterer, Ingrid, and Baudoux, Anne-Claire
Subjects: ATMOSPHERIC aerosols, ATMOSPHERIC deposition, DUST, BIOGEOCHEMICAL cycles, TRACE metals, MINERAL dusts, BACTERIAL communities, MICROBIOLOGICAL aerosols
Abstract: In the oligotrophic waters of the Mediterranean Sea, during the stratification period, the microbial loop relies on pulsed inputs of nutrients through atmospheric deposition of aerosols from both natural (Saharan dust) and anthropogenic origins. While the influence of dust deposition on microbial processes and community composition is still not fully constrained, the extent to which future environmental conditions will affect dust inputs and the microbial response is not known. The impact of atmospheric wet dust deposition was studied both under present and future (warming and acidification) environmental conditions through experiments in 300 L climate reactors. Three dust addition experiments were performed with surface seawater collected from the Tyrrhenian Sea, Ionian Sea and Algerian basin in the Western Mediterranean Sea during the PEACETIME cruise in May-June 2017. Top-down controls on bacteria, viral processes and community, as well as microbial community structure (16S and 18S rDNA amplicon sequencing) were followed over the 3-4 days experiments. Different microbial and viral responses to dust were observed rapidly after addition and were most of the time higher when combined to future environmental conditions. The input of nutrients and trace metals changed the microbial ecosystem from bottom-up limited to a top-down controlled bacterial community, likely from grazing and induced lysogeny. The composition of mixotrophic microeukaryotes and phototrophic prokaryotes was also altered. Overall, these results suggest that the effect of dust deposition on the microbial loop is dependent on the initial microbial assemblage and metabolic state of the tested water, and that predicted warming, and acidification will intensify these responses, affecting food web processes and biogeochemical cycles. [ABSTRACT FROM AUTHOR]
Published: 2021
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41. Influence of atmospheric deposition on biogeochemical cycles in an oligotrophic ocean system.

Author: Van Wambeke, France, Taillandier, Vincent, Deboeufs, Karine, Pulido-Villena, Elvira, Dinasquet, Julie, Engel, Anja, Marañón, Emilio, Ridame, Céline, and Guieu, Cécile
Subjects: ATMOSPHERIC deposition, MIXING height (Atmospheric chemistry), OCEAN, MINERAL dusts, CHLOROPHYLL, PROKARYOTES, NITROGEN fixation
Abstract: The surface mixed layer (ML) in the Mediterranean Sea is a well stratified domain characterized by low macro-nutrient and low chlorophyll content, during almost 6 months of the year. Nutrient dynamics in the ML depend on allochthonous inputs, through atmospheric deposition and on biological recycling. Here we characterize the biogeochemical cycling of N in the ML by combining simultaneous in situ measurements of atmospheric deposition, nutrients, hydrological conditions, primary production, heterotrophic prokaryotic production, N2 fixation and leucine aminopeptidase activity. The measurements were conducted along a 4300 km transect across the central and western open Mediterranean Sea in spring 2017. Dry deposition was measured on a continuous basis while two wet deposition events were sampled, one in the Ionian Sea and one in the Algerian basin. Along the transect, N budgets were computed to compare sources and sinks of N in the mixed layer. On average, phytoplankton N demand was 2.9 fold higher (range 1.5-8.1) than heterotrophic prokaryotic N demand. In situ leucine aminopeptidase activity contributed from 14 to 66 % of heterotrophic prokaryotic N demand, and N2 fixation rate represented 1 to 4.5 % of the phytoplankton N demand. Dry atmospheric deposition of inorganic nitrogen, estimated from dry deposition of (nitrate + ammonium) in aerosols, was higher than N2 fixation rates in the ML (on average 4.8 fold). The dry atmospheric input of inorganic N represented a highly variable proportion of biological N demand in the ML, 10-82 % for heterotrophic prokaryotes and 1-30 % for phytoplankton. Stations visited for several days allowed following the evolution of biogeochemical properties in the ML and within the nutrient depleted layers. At the site in the Algerian Basin and on a basis of high frequency sampling of CTD casts before and after a wet dust deposition event, different scenarios were considered to explain a delayed appearance of peaks in dissolved inorganic phosphate in comparison to nitrate within the ML. After the rain, nitrate was higher in the ML than in the nutrient depleted layer below. Estimates of nutrient transfer from the ML to the nutrient depleted layer could explain 1/3 of the nitrate fate out of the ML. Luxury consumption of P by heterotrophic prokaryotes, further transferred in the microbial food web, and remineralized by grazers, is one explanation for the delayed phosphate peak of DIP. The second explanation is a transfer from ML to the nutrient depleted layer below through adsorption/desorption processes on particles. Phytoplankton did not benefit directly from atmospheric inputs in the ML, probably due to a high competition with heterotrophic prokaryotes, also limited by N and P availability at the time of this study. Primary producers, in competition for nutrients with heterotrophic prokaryotes, decreased their production after the rain, recovering their initial state of activity after 2 days lag in the vicinity of the deep chlorophyll maximum layer. [ABSTRACT FROM AUTHOR]
Published: 2020
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42. Impact of dust enrichment on Mediterranean plankton communities under present and future conditions of pH and temperature: an experimental overview.

Author: Gazeau, Frédéric, Ridame, Céline, Van Wambeke, France, Alliouane, Samir, Stolpe, Christian, Irisson, Jean-Olivier, Marro, Sophie, Grisoni, Jean-Michel, De Liège, Guillaume, Nunige, Sandra, Djaoudi, Kahina, Pulido-Villena, Elvira, Dinasquet, Julie, Obernosterer, Ingrid, Catala, Philippe, and Guieu, Cécile
Subjects: MINERAL dusts, ATMOSPHERIC deposition, DUST, OCEAN acidification, TERRITORIAL waters, WATER, COMMUNITIES
Abstract: In Low Nutrient Low Chlorophyll areas, such as the Mediterranean Sea, atmospheric fluxes represent a considerable external source of nutrients likely supporting primary production especially during stratification periods. These areas are expected to expand in the future due to lower nutrient supply from sub-surface waters caused by enhanced stratification, likely further increasing the role of atmospheric deposition as a source of new nutrients to surface waters. Yet, whether plankton communities will react differently to dust deposition in a warmer and acidified environment remains an open question. The impact of dust deposition both in present and future climate conditions was assessed through three perturbation experiments in the open Mediterranean Sea. Climate reactors (300 L) were filled with surface water collected in the Tyrrhenian Sea, Ionian Sea and in the Algerian basin during a cruise conducted in May/June 2017 in the frame of the PEACETIME project. The experimental protocol comprised two unmodified control tanks, two tanks enriched with a Saharan dust analog and two tanks enriched with the dust analog and maintained under warmer (+3 °C) and acidified (-0.3 pH unit) conditions. Samples for the analysis of an extensive number of biogeochemical parameters and processes were taken over the duration of the experiments (3-4 d). Here, we present the general setup of the experiments and the impacts of dust seeding and/or future climate change scenario on nutrients and biological stocks. Dust addition led to a rapid and maximum input of nitrate whereas phosphate release from the dust analog was much smaller. Our results showed that the impacts of Saharan dust deposition in three different basins of the open Northwestern Mediterranean Sea are at least as strong as those observed previously in coastal waters. However, interestingly, the effects of dust deposition on biological stocks were highly different between the three investigated stations and could not be attributed to differences in their degree of oligotrophy but rather to the initial metabolic state of the community. Finally, ocean acidification and warming did not drastically modify the composition of the autotrophic assemblage with all groups positively impacted by warming and acidification, suggesting an exacerbation of effects from atmospheric dust deposition in the future. [ABSTRACT FROM AUTHOR]
Published: 2020
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43. Contrasted release of insoluble elements (Fe, Al, REE, Th, Pa) after dust deposition in seawater: a tank experiment approach.

Author: Roy-Barman, Matthieu, Folio, Lorna, Douville, Eric, Leblond, Nathalie, Gazeau, Frédéric, Bressac, Matthieu, Wagener, Thibaut, Ridame, Céline, Desboeufs, Karine, and Guieu, Cécile
Subjects: DUST, RARE earth metals, DUST control, TANKS, SEAWATER
Abstract: The release of lithogenic elements (which are often assumed to be insoluble) such as Aluminum (Al), Iron (Fe), Rare Earth Elements (REE), Thorium (Th) and Protactinium (Pa) by Saharan dust reaching Mediterranean seawater was studied through tank experiments over 3 to 4 days under controlled conditions including control without dust addition and dust seeding under present and future climate conditions (+3 °C and -0.3 pH unit). Unfiltered surface seawater from 3 oligotrophic regions (Tyrrhenian Sea, Ionian Sea and Algerian Basin) were used. The maximum dissolution fractions were low for all seeding experiments: less than 0.3% for Fe, 1% for [sup 232]Th and Al, about 2-5% for REE and less than 6% for Pa. Different behaviors were observed: dissolved Al increased until the end of the experiments, Fe did not dissolve significantly and Th and light REE were scavenged back on the particles after a fast initial release. The constant [sup 230]Th/[sup 232]Th ratio during the scavenging phase suggests that there is little or no further dissolution after the initial Th release. Quite unexpectedly, comparison of present and future conditions indicates that changes in temperature and/or pH influence the release of thorium and REE in seawater, leading to a lower Th release and a higher light REE release under increased greenhouse conditions. [ABSTRACT FROM AUTHOR]
Published: 2020
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44. Rapid establishment of the CO2 sink associated with Kerguelen's bloom observed during the KEOPS2/OISO20 cruise

Author: Lo Monaco, Claire, Metzl, Nicolas, D'Ovidio, Francesco, Llort, Joan, Ridame, Céline, Équipe CO2 (E-CO2), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Processus de couplage à Petite Echelle, Ecosystèmes et Prédateurs Supérieurs (PEPS), Biogéochimie-Traceurs-Paléoclimat (BTP), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636))
Subjects: [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]
Abstract: International audience; Iron and light are the main factors limiting the biological pump of CO2 in the Southern Ocean. Iron fertilization experiments have demonstrated the potential for increased uptake of atmospheric CO2, but little is known about the evolution of fertilized environnements. This paper presents observations collected in one of the largest phytoplankton bloom of the Southern Ocean sustained by iron originating from the Kerguelen Plateau. We first complement previous studies by investigating the mechanisms that control air–sea CO2 fluxes over and downstream of the Kerguelen Plateau at the onset of the bloom based on measurements obtained in October–November 2011. These new observations show the rapid establishment of a strong CO2 sink in waters fertilized with iron as soon as vertical mixing is reduced. The magnitude of the CO2 sink was closely related to chlorophyll a and iron concentrations. Because iron concentration strongly depends on the distance from the iron source and the mode of delivery, we identified lateral advection as the main mechanism controlling air–sea CO2 fluxes downtream the Kerguelen Plateau during the growing season. In the southern part of the bloom, situated over the Plateau (iron source), the CO2 sink was stronger and spatially more homogeneous than in the plume offshore. However, we also witnessed a substantial reduction in the uptake of atmospheric CO2 over the Plateau following a strong winds event. Next, we used all the data available in this region in order to draw the seasonal evolution of air–sea CO2 fluxes. The CO2 sink is rapidly reduced during the course of the growing season, which we attribute to iron and silicic acid depletion. South of the Polar Front, where nutrients depletion is delayed, we suggest that the amplitude and duration of the CO2 sink is mainly controlled by vertical mixing. The impact of iron fertilization on air–sea CO2 fluxes is revealed by comparing the uptake of CO2 integrated over the productive season in the bloom, between 1 and 1.5 mol C m−2 yr−1, and in the iron-poor HNLC waters, where we found a typical value of 0.4 mol C m−2 yr−1. Extrapolating our results to the ice-free Southern Ocean (~50–60° S) suggests that iron fertilization of the whole area would increase the contemporay oceanic uptake of CO2 by less than 0.1 Pg C yr−1, i.e., less than 1% of the current anthropogenic CO2 emissions.
Published: 2014

45. Iron limitation and DMSP in diatoms and cyanobacteria

Author: Bucciarelli, Eva, Sarthou, Géraldine, Cheize, Marie, Ridame, Céline, Dimier-Hugueney, Céline, Biogéochimie-Traceurs-Paléoclimat (BTP), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636))
Subjects: [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2014

46. Correction: Response of the Unicellular Diazotrophic Cyanobacterium Crocosphaera watsonii to Iron Limitation (vol 9, e86749, 2014)

Author: Jacq, Violaine, Ridame, Céline, L'Helguen, Stéphane, Kaczmar, Fanny, Saliot, Alain, Biogéochimie-Traceurs-Paléoclimat (BTP), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), 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), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and 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 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)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDE.BE]Environmental Sciences/Biodiversity and Ecology, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract: International audience
Published: 2014

47. NUTRIENTS AND SAHARAN DUST EVENTS CONTROL UNICELLULAR DIAZOTROPHIC CYANOBACTERIA DEVLOPMENT IN OLIGOTROPHIC MEDITERRANEAN SEA

Author: Hamza, Ismail, Le Moal, Morgane, Périot, Marine, Ridame, Céline, Tanaka, Tsuneo, Biegala, Isabelle, Institut de Recherche pour le Développement (IRD), 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), and BIEGALA, ISABELLE
Subjects: [SDE] Environmental Sciences, [SDV] Life Sciences [q-bio], [SDV]Life Sciences [q-bio], [SDE]Environmental Sciences
Abstract: International audience
Published: 2013

48. Nutrient control of N2 fixation in the oligotrophic Mediterranean Sea and the impact of Saharan dust events

Author: Ridame, Céline, Le Moal, M., Guieu, Cécile, Ternon, E., Biegala, Isabelle C., L'Helguen, Stéphane, Pujo-Pay, Mireille, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie et de biogéochimie (LOB), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), 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 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)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie Microbienne (LOMIC), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), and Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: lcsh:Geology, lcsh:QH501-531, [SDU]Sciences of the Universe [physics], lcsh:QH540-549.5, lcsh:QE1-996.5, [SDE]Environmental Sciences, lcsh:Life, Earth Science, lcsh:Ecology
Abstract: International audience; A better understanding of the factors controlling N2 fixation is a pre-requisite for improving our knowledge on the contribution of N2 fixation process in the nitrogen cycling. Trace-metal clean nutrient/dust addition bioassays (+P, +PFe, +dust) were performed at three stations located in the western, central and eastern Mediterranean Sea, in summer 2008 as part of the BOUM cruise. The main goals were (1) to investigate the nutrient factor(s) limiting N2 fixation (uptake of 15N2) and (2) to evaluate the potential impact of a Saharan dust event on this biological process during the stratification period. Initially, surface waters at the three stations were DIP-depleted (2 fixation (from 130 % to 430 %). The highest dust stimulation of N2 fixation was recorded at the station located in the eastern basin. The response of diazotrophic activity to nutrient additions was variable between the sampled stations suggesting a spatial variability of the factor controlling N2 fixation over the whole basin. At all stations, N2 fixation was not limited by Fe nor co-limited by P and Fe. At the western station, N2 fixation was DIP limited while at the eastern one, N2 fixation was first DIP limited, then was limited by one or several chemical element(s) released by dust. Our results demonstrated that a Saharan dust input was able to relieve these successive on going limitations. Very interestingly, at the station located in the central basin, N2 fixation was not limited by the availability of P yet it was strongly stimulated by dust addition (x3.1). A chemical element or a combination of several, released by the added dust may have been responsible for the observed stimulations of N2 fixation. These results indicated that Saharan dust pulses to the surface Mediterranean waters, in addition to P and Fe, could be a source of chemical(s) element(s) that are necessary for metabolic processes and therefore influence rates of N2 fixation.
Published: 2011

49. Response of the Unicellular Diazotrophic Cyanobacterium Crocosphaera watsonii to Iron Limitation

Author: Jacq, Violaine, primary, Ridame, Céline, additional, L'Helguen, Stéphane, additional, Kaczmar, Fanny, additional, and Saliot, Alain, additional
Published: 2014
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50. Impact of high Saharan dust inputs on dissolved iron distributions in the Mediterranean Sea

Author: Guieu, Cécile, Bozec, Yann, Blain, Stéphane, Ridame, Céline, Sarthou, Géraldine, Leblond, Nathalie, Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie et de biogéochimie (LOB), Université de la Méditerranée - Aix-Marseille 2-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 4850), 1050 Geochemistry: Marine geochemistry (4835, 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 1065 Geochemistry: Trace elements (3670)
Abstract: International audience; During the PROSOPE cruise (Sept. 1999) in the Mediterranean Sea, dissolved iron concentrations in seawater and iron and aluminium concentrations in aerosols collected on board were investigated. Concentrations in aerosols were about two times higher in the Tyrrhenian Sea than in the west (Alboran Sea). This was in good agreement with the observed increase in dissolved iron concentrations in the surface waters from West to East. Depth profiles were characterised by a maximum in the surface mixed layer. Using an in vitro experiment, iron released from Saharan dust during the season characterized by a stratified water column and a low primary productivity was estimated: it resulted in an accumulation of 0.5-0.8 nM dissolved iron, in good agreement with the observed iron enrichment in the surface water (0.8 nM). This study confirms the significance of atmospheric input of Saharan origin on the iron cycle in the Mediterranean Sea.
Published: 2002

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