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1. L'acidification des océans

Author

Pernet, Fabrice and Gazeau, Frédéric

Subjects
seaweed, aquaculture, biodiversity, climate, shellfish, crustacean, sustainable development, seawater, ecology, ecosystem, seabed, fisheries, oyster, sea, mollusc, oceanography, fish, pollution, seafood, forecast, fisheries resources, sediment, toxicity, thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RB Earth sciences::RBK Hydrology and the hydrosphere::RBKC Oceanography (seas and oceans), thema EDItEUR::W Lifestyle, Hobbies and Leisure::WN Nature and the natural world: general interest::WNC Wildlife: general interest::WNCS Wildlife: aquatic creatures: general interest::WNCS1 Sea life and the seashore: general interest, thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RN The environment::RNP Pollution and threats to the environment::RNPG Climate change
Abstract

Carbon dioxide (CO2) emissions, resulting from the combustion of fossil fuels by human activity, reinforce the greenhouse effect and cause climate disruption. While public awareness of this global problem is growing, ocean acidification, described as "the other CO2 problem", is still largely unknown. This book answers ten key questions on the biogeochemical foundations of acidification, past, current and future trends, the impact on marine organisms and on humans, and finally, ways to remedy the situation. It draws its answers from fields as diverse as biogeochemistry, ecology, physiology, evolution, aquaculture and fisheries, economics and sociology.

Published
2024
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2. An updated synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2023: the SNAPO-CO2-v2 dataset.

Author

Metzl, Nicolas, Fin, Jonathan, Monaco, Claire Lo, Mignon, Claude, Alliouane, Samir, Bombled, Bruno, Boutin, Jacqueline, Bozec, Yann, Comeau, Steeve, Conan, Pascal, Coppola, Laurent, Cuet, Pascale, Ferreira, Eva, Gattuso, Jean-Pierre, Gazeau, Frédéric, Goyet, Catherine, Grossteffan, Emilie, Lansard, Bruno, Lefèvre, Dominique, and Lefèvre, Nathalie

Subjects
OCEAN acidification, POTENTIOMETRY, COASTS, DATABASES, REFERENCE sources, CARBON cycle
Abstract

Total alkalinity (A T) and dissolved inorganic carbon (C T) in the oceans are important properties to understand the ocean carbon cycle and its link with global change (ocean carbon sinks and sources, ocean acidification) and ultimately find carbon based solutions or mitigation procedures (marine carbon removal). We present an extended database (SNAPO-CO2, Metzl et al, 2024d) with 24700 new additional data for the period 2002 to 2023. The full database now includes more than 67000 A T and C T observations along with basic ancillary data (time and space location, depth, temperature and salinity) in various oceanic regions obtained since 1993 mainly in the frame of French research projects. This includes both surface and water columns data acquired in open oceans, coastal zones, rivers and in the Mediterranean Sea and either from time-series or punctual cruises. Most A T and C T data in this synthesis were measured from discrete samples using the same closed-cell potentiometric titration calibrated with Certified Reference Material, with an overall accuracy of ± 4 µmol kg-1 for both A T and C T. The same technique was used onboard for underway measurements during cruises conducted in the Southern Indian and Southern Oceans. The A T and C T data from these cruises are also added in this synthesis. The data are provided in one dataset for the global ocean (https://doi.org/10.17882/102337) that offers a direct use for regional or global purposes, e.g. A T/Salinity relationships, long-term C T estimates, constraint and validation of diagnostics C T and A T reconstructed fields or ocean carbon and coupled climate/carbon models simulations, as well as data derived from Biogeochemical-Argo (BGC-Argo) floats. These data can also be used to calculate pH, fugacity of CO2 (f CO2) and other carbon system properties to derive ocean acidification rates or air-sea CO2 fluxes. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Multifactorial effects of warming, low irradiance, and low salinity on Arctic kelps.

Author

Lebrun, Anaïs, Miller, Cale A., Meynadier, Marc, Comeau, Steeve, Urrutti, Pierre, Alliouane, Samir, Schlegel, Robert, Gattuso, Jean-Pierre, and Gazeau, Frédéric

Subjects
BEACH erosion, GLACIAL melting, SEA ice, CONDITIONED response, INVESTIGATIONAL therapies, LAMINARIA
Abstract

The Arctic is projected to warm by 2 to 5 °C by the end of the century. Warming causes melting of glaciers, shrinking of the areas covered by sea ice, and increased terrestrial runoff from snowfields and permafrost thawing. Warming, decreasing coastal underwater irradiance, and lower salinity are potentially threatening polar marine organisms, including kelps, that are key species of hard-bottom shallow communities. The present study investigates the physiological responses of four kelp species (Alaria esculenta, Laminaria digitata, Saccharina latissima, and Hedophyllum nigripes) to these environmental changes through a perturbation experiment in ex situ mesocosms. Kelps were exposed for 6 weeks to four experimental treatments: an unmanipulated control; a warming condition under the CO2 emission scenario SSP5-8.5; and two multifactorial conditions combining warming, low salinity, and low irradiance reproducing the future coastal Arctic exposed to terrestrial runoff under two CO2 emission scenarios (SSP2-4.5 and SSP5-8.5). The physiological effects on A. esculenta, L. digitata, and S. latissima were investigated, and gene expression patterns of S. latissima and H. nigripes were analyzed. Across all species and experimental treatments, growth rates were similar, underlying the acclimation potential of these species to future Arctic conditions. Specimens of A. esculenta increased their chlorophyll a content when exposed to low irradiance conditions, suggesting that they may be resilient to an increase in glacier and river runoff with the potential to become more dominant at greater depths. S. latissima showed a lower carbon : nitrogen (C : N) ratio under the SSP5-8.5 multifactorial conditions' treatment, suggesting tolerance to coastal erosion and permafrost thawing. In contrast, L. digitata showed no response to the conditions tested on any of the investigated physiological parameters. The down-regulation of genes coding for heat-shock proteins in H. nigripes and S. latissima underscores their ability to acclimate to heat stress, which portrays temperature as a key influencing factor. Based on these results, it is expected that kelp communities will undergo changes in species composition that will vary at local scale as a function of the changes in environmental drivers. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Summer primary production of Arctic kelp communities is more affected by duration than magnitude of simulated marine heatwaves.

Author

Miller, Cale A., Gazeau, Frédéric, Lebrun, Anaïs, Alliouane, Samir, Urrutti, Pierre, Schlegel, Robert W., Gattuso, Jean‐Pierre, and Comeau, Steeve

Subjects
*MARINE heatwaves, *HEAT waves (Meteorology), *NUTRIENT uptake, *BIOGEOCHEMICAL cycles, *KELPS
Abstract

Fjord systems in the Norwegian Arctic are experiencing an increasing frequency and magnitude of marine heatwaves. These episodic heat stress events can have varying degrees of acute impacts on primary production and nutrient uptake of mixed kelp communities, as well as modifying the biogeochemical cycling in nearshore systems where vast areas of kelp create structural habitat. To assess the impact of future marine heatwaves on kelp communities, we conducted a 23 day mesocosm experiment exposing mixed kelp communities to warming and heatwave scenarios projected for the year 2100. Three treatments were considered: a constant warming (+1.8°C from the control), a medium magnitude and long duration heatwave event (+2.8°C from the control for 13 days), and two short‐term, more intense, heatwaves(5 day long scenarios with temperature peaks at +3.9°C from the control). The results show that both marine heatwave treatments reduced net community production, whereas the constant warm temperature treatment displayed no difference from the control. The long marine heatwave scenario resulted in reduced accumulated net community production, indicating that prolonged exposure had a greater severity than two high magnitude, short‐term heatwave events. We estimated an 11°C temperature threshold at which negative effects to primary production appeared present. We highlight that marine heatwaves can induce sublethal effects on kelp communities by depressing net community production. These results are placed in the context of potential physiological resilience of kelp communities and implications of reduced net community production to future Arctic fjord environmental conditions. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Toward an ecologically realistic experimental system to investigate the multigenerational effects of ocean warming and acidification on benthic invertebrates.

Author

Gazeau, Frédéric, Urrutti, Pierre, Dousset, Alexandre, Brodu, Nicolas, Richard, Marion, Villeneuve, Rémi, Pruvost, Éric, Comeau, Steeve, Koechlin, Hugo, and Pernet, Fabrice

Subjects
OCEAN acidification, OCEAN temperature, GLOBAL warming, CARBON dioxide, AGRICULTURE
Abstract

Human activities over the past 150 yr have led to significant carbon dioxide (CO2) emissions, causing global warming and ocean acidification. Surface ocean temperature has risen by 0.93°C since 1850, with projections of an additional +1.42°C to 3.47°C by 2080–2099. Ocean acidification, driven by CO2 absorption, has already lowered seawater pH by 0.1 units, affecting calcifying organisms, including shelled mollusks. Long‐term multigenerational studies on mollusk responses to both ocean acidification and warming, under realistic environmental conditions, are scarce. To address this knowledge gap, two mobile experimental units that can be deployed at the vicinity of shellfish farming areas were developed within the framework of the CocoriCO2 project. The experimental systems were designed to manipulate temperature and pH as offsets from ambient conditions. The experimental units have shown their effectiveness in terms of controlling and maintaining pH and temperature to assess the multigenerational effects of ocean warming and acidification on benthic invertebrates. Finally, the developed experimental systems can be modified easily to provide an educated assessment of the impact of other relevant environmental changes such as deoxygenation and changes in salinity. [ABSTRACT FROM AUTHOR]

Published
2024
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6. An update of data compilation on the biological response to ocean acidification and overview of the OA-ICC data portal.

Author

Yang, Yan, Brockmann, Patrick, Galdino, Carolina, Schindler, Uwe, and Gazeau, Frédéric

Subjects
OCEAN acidification, DATA libraries, MARINE organisms, MOLLUSKS, CNIDARIA
Abstract

The number of studies investigating the effects of ocean acidification on marine organisms and communities increases every year. Results are not easily comparable since the carbonate chemistry and ancillary data are not always reported in similar units and scales and are not calculated using similar sets of constants. To facilitate data comparison, a data compilation hosted by the PANGAEA Data Publisher was initiated in 2008 and is updated on a regular basis (10.1594/PANGAEA.962556; Ocean Acidification International Coordination Centre (OA-ICC), 2023). By November 2023, a total of 1501 datasets (over 25 million data points) from 1554 papers had been archived. To easily filter and access relevant biological response data from this compilation, a user-friendly portal (https://oa-icc.ipsl.fr , last access: 9 November 2023) was launched in 2018. Here, we present an update of this data compilation since its second description by Yang et al. (2016) and provide an overview of the OA-ICC portal for ocean acidification biological response data, launched in 2018. Most of the study sites from which data have been archived are in the North Atlantic Ocean, North Pacific Ocean, South Pacific Ocean, and Mediterranean Sea, while polar oceans are still relatively poorly represented. Mollusca and Cnidaria are still the best-represented taxonomic groups. The biological processes most reported in the datasets are growth and morphology. Other variables that can potentially be affected by ocean acidification and are often reported include calcification/dissolution, primary production/photosynthesis, and biomass/abundance. The majority of the compiled datasets have considered ocean acidification as a single stressor, but their relative contribution has decreased from 68 % before 2015 to 57 % today, showing a clear tendency towards more data archived from multifactorial studies. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Productivity of mixed kelp communities in an Arctic fjord exhibit tolerance to a future climate

Author

Miller, Cale A., Gazeau, Frédéric, Lebrun, Anaïs, Gattuso, Jean Pierre, Alliouane, Samir, Urrutti, Pierre, Schlegel, Robert W., Comeau, Steeve, Miller, Cale A., Gazeau, Frédéric, Lebrun, Anaïs, Gattuso, Jean Pierre, Alliouane, Samir, Urrutti, Pierre, Schlegel, Robert W., and Comeau, Steeve

Abstract

Arctic fjords are considered to be one of the ecosystems changing most rapidly in response to climate change. In the Svalbard archipelago, fjords are experiencing a shift in environmental conditions due to the Atlantification of Arctic waters and the retreat of sea-terminating glaciers. These environmental changes are predicted to facilitate expansion of large, brown macroalgae, into new ice-free regions. The potential resilience of macroalgal benthic communities in these fjord systems will depend on their response to combined pressures from freshening due to glacial melt, exposure to warmer waters, and increased turbidity from meltwater runoff which reduces light penetration. Current predictions, however, have a limited ability to elucidate the future impacts of multiple-drivers on macroalgal communities with respect to ecosystem function and biogeochemical cycling in Arctic fjords. To assess the impact of these combined future environmental changes on benthic productivity and resilience, we conducted a two-month mesocosm experiment exposing mixed kelp communities to three future conditions comprising increased temperature (+ 3.3 and + 5.3°C), seawater freshening by ∼ 3.0 and ∼ 5.0 units (i.e., salinity of 30 and 28, respectively), and decreased photosynthetically active radiation (PAR, - 25 and - 40 %). Exposure to these combined treatments resulted in non-significant differences in short-term productivity, and a tolerance of the photosynthetic capacity across the treatment conditions. We present the first robust estimates of mixed kelp community production in Kongsfjorden and place a median compensation irradiance of ∼12.5 mmol photons m−2 h−1 as the threshold for positive net community productivity. These results are discussed in the context of ecosystem productivity and biological tolerance of kelp communities in future Arctic fjord systems.

Published
2024

8. A synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2022: the SNAPO-CO2-v1 dataset

Author

Metzl, Nicolas, Fin, Jonathan, Lo Monaco, Claire, Mignon, Claude, Alliouane, Samir, Antoine, David, Bourdin, Guillaume, Boutin, Jacqueline, Bozec, Yann, Conan, Pascal, Coppola, Laurent, Diaz, Frédéric, Douville, Eric, Durrieu de Madron, Xavier, Gattuso, Jean-Pierre, Gazeau, Frédéric, Golbol, Melek, Lansard, Bruno, Lefèvre, Dominique, Lefèvre, Nathalie, Lombard, Fabien, Louanchi, Férial, Merlivat, Liliane, Olivier, Léa, Petrenko, Anne, Petton, Sébastien, Pujo-Pay, Mireille, Rabouille, Christophe, Reverdin, Gilles, Ridame, Céline, Tribollet, Aline, Vellucci, Vincenzo, Wagener, Thibaut, Wimart-Rousseau, Cathy, Metzl, Nicolas, Fin, Jonathan, Lo Monaco, Claire, Mignon, Claude, Alliouane, Samir, Antoine, David, Bourdin, Guillaume, Boutin, Jacqueline, Bozec, Yann, Conan, Pascal, Coppola, Laurent, Diaz, Frédéric, Douville, Eric, Durrieu de Madron, Xavier, Gattuso, Jean-Pierre, Gazeau, Frédéric, Golbol, Melek, Lansard, Bruno, Lefèvre, Dominique, Lefèvre, Nathalie, Lombard, Fabien, Louanchi, Férial, Merlivat, Liliane, Olivier, Léa, Petrenko, Anne, Petton, Sébastien, Pujo-Pay, Mireille, Rabouille, Christophe, Reverdin, Gilles, Ridame, Céline, Tribollet, Aline, Vellucci, Vincenzo, Wagener, Thibaut, and Wimart-Rousseau, Cathy

Abstract

Total alkalinity (AT) and dissolved inorganic carbon (CT) in the oceans are important properties with respect to understanding the ocean carbon cycle and its link to global change (ocean carbon sinks and sources, ocean acidification) and ultimately finding carbon-based solutions or mitigation procedures (marine carbon removal). We present a database of more than 44 400 AT and CT observations along with basic ancillary data (spatiotemporal location, depth, temperature and salinity) from various ocean regions obtained, mainly in the framework of French projects, since 1993. This includes both surface and water column data acquired in the open ocean, coastal zones and in the Mediterranean Sea and either from time series or dedicated one-off cruises. Most AT and CT data in this synthesis were measured from discrete samples using the same closed-cell potentiometric titration calibrated with Certified Reference Material, with an overall accuracy of ±4 µmol kg−1 for both AT and CT. The data are provided in two separate datasets – for the Global Ocean and the Mediterranean Sea (https://doi.org/10.17882/95414, Metzl et al., 2023), respectively – that offer a direct use for regional or global purposes, e.g., AT–salinity relationships, long-term CT estimates, and constraint and validation of diagnostic CT and AT reconstructed fields or ocean carbon and coupled climate–carbon models simulations as well as data derived from Biogeochemical-Argo (BGC-Argo) floats. When associated with other properties, these data can also be used to calculate pH, the fugacity of CO2 (fCO2) and other carbon system properties to derive ocean acidification rates or air–sea CO2 fluxes.

Published
2024
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9. Productivity of mixed kelp communities in an Arctic fjord exhibit tolerance to a future climate

Author

Geochemistry, IVAU: Instituut voor Aardwetenschappen Utrecht, Miller, Cale A., Gazeau, Frédéric, Lebrun, Anaïs, Gattuso, Jean Pierre, Alliouane, Samir, Urrutti, Pierre, Schlegel, Robert W., Comeau, Steeve, Geochemistry, IVAU: Instituut voor Aardwetenschappen Utrecht, Miller, Cale A., Gazeau, Frédéric, Lebrun, Anaïs, Gattuso, Jean Pierre, Alliouane, Samir, Urrutti, Pierre, Schlegel, Robert W., and Comeau, Steeve

Published
2024

10. 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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14. Influence of shallow hydrothermal fluid release on the functioning of phytoplankton communities

Author

Tilliette, Chloé, primary, Gazeau, Frédéric, additional, Portlock, Gemma, additional, Benavides, Mar, additional, Bonnet, Sophie, additional, Guigue, Catherine, additional, Leblond, Nathalie, additional, Lory, Caroline, additional, Marie, Dominique, additional, Montanes, Maryline, additional, Pulido-Villena, Elvira, additional, Sarthou, Géraldine, additional, Tedetti, Marc, additional, Vorrath, Maria-Elena, additional, Whitby, Hannah, additional, and Guieu, Cécile, additional

Published
2023
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15. Temporal and spatial variability in the hydrothermal signature of sinking particles and sediments in the Western Tropical South Pacific Ocean

Author

Tilliette, Chloé, Gazeau, Frédéric, Chavagnac, Valerie, Leblond, Nathalie, Montanes, Maryline, Leblanc, Karine, Schmidt, Sabine, Charrière, Bruno, Bhairy, Nagib, Guieu, Cécile, Tilliette, Chloé, Gazeau, Frédéric, Chavagnac, Valerie, Leblond, Nathalie, Montanes, Maryline, Leblanc, Karine, Schmidt, Sabine, Charrière, Bruno, Bhairy, Nagib, and Guieu, Cécile

Abstract

Iron (Fe) is an essential micronutrient for phytoplankton, particularly diazotrophs, which are abundant in the Western Tropical South Pacific Ocean (WTSP). Their success depends on the numerous trace metals, particularly iron, released from shallow hydrothermal vents along the Tonga Arc. This study aimed to explore the impact of hydrothermal fluids on particulate trace metal concentrations and biological activity. To identify the composition of sinking particles across a wide area of the WTSP, we deployed sediment traps at various depths, both close and further west of the Tonga Arc. Seafloor sediments were cored at these deployment sites, including at a remote location in the South Pacific Gyre. The sinking particles were composed of a large amount of biological material, indicative of the high productivity of the Lau Basin. A significant portion of this material was lithogenic of hydrothermal origin, as revealed through Al-Fe-Mn tracing. The sinking material showed similar patterns between lithogenic and biogenic fractions, indicating that hydrothermal input within the photic layer triggered surface production. A hydrothermal fingerprint was suggested in the sediments due to the high sedimentation rates and the presence of large, heterogeneous, trace metal-rich particles. The presence of nearby active deep hydrothermal sources was suspected near the Lau Ridge due to the large particle size and the significant enrichment of Fe and Mn. Overall, this study revealed that deep and shallow hydrothermal sources along with submarine volcanism have a significant influence on the biogeochemical signature of particles in the Lau Basin at large spatial and temporal scales.

Published
2023
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16. Influence of shallow hydrothermal fluid release on the functioning of phytoplankton communities

Author

Tilliette, Chloé, Gazeau, Frédéric, Portlock, Gemma, Benavides, Mar, Bonnet, Sophie, Guigue, Catherine, Leblond, Nathalie, Lory, Caroline, Marie, Dominique, Montanes, Maryline, Pulido-villena, Elvira, Sarthou, Geraldine, Tedetti, Marc, Vorrath, Maria-elena, Whitby, Hannah, Guieu, Cécile, Tilliette, Chloé, Gazeau, Frédéric, Portlock, Gemma, Benavides, Mar, Bonnet, Sophie, Guigue, Catherine, Leblond, Nathalie, Lory, Caroline, Marie, Dominique, Montanes, Maryline, Pulido-villena, Elvira, Sarthou, Geraldine, Tedetti, Marc, Vorrath, Maria-elena, Whitby, Hannah, and Guieu, Cécile

Abstract

In the Western Tropical South Pacific (WTSP) Ocean, a hotspot of dinitrogen fixation has been identified. The survival of diazotrophs depends, among others, on the availability of dissolved iron (DFe) largely originating, as recently revealed, from shallow hydrothermal sources located along the Tonga-Kermadec arc that fertilize the Lau Basin with this element. On the opposite, these fluids, released directly close to the photic layer, can introduce numerous trace metals at concentrations that can be toxic to surface communities. Here, we performed an innovative 9-day experiment in 300 L reactors onboard the TONGA expedition, to examine the effects of hydrothermal fluids on natural plankton communities in the WTSP Ocean. Different volumes of fluids were mixed with non-hydrothermally influenced surface waters (mixing ratio from 0 to 14.5%) and the response of the communities was studied by monitoring numerous stocks and fluxes (phytoplankton biomass, community composition, net community production, N2 fixation, thiol production, organic carbon and metal concentrations in exported material). Despite an initial toxic effect of hydrothermal fluids on phytoplankton communities, these inputs led to higher net community production and N2 fixation rates, as well as elevated export of organic matter relative to control. This fertilizing effect was achieved through detoxification of the environment, rich in potentially toxic elements (e.g., Cu, Cd, Hg), likely by resistant Synechococcus ecotypes able to produce strong binding ligands, especially thiols (thioacetamide-like and glutathione-like compounds). The striking increase of thiols quickly after fluid addition likely detoxified the environment, rendering it more favorable for phytoplankton growth. Indeed, phytoplankton groups stressed by the addition of fluids were then able to recover important growth rates, probably favored by the supply of numerous fertilizing trace metals (notably Fe) from hydrothermal fluids and new n

Published
2023
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17. Natural iron fertilization by shallow hydrothermal sources fuels diazotroph blooms in the Ocean

Author

2., B, Guieu, C, Taillandier, V, Boulart, C, Bouruet-Aubertot, P, Gazeau, F, Scalabrin, C, Bressac Matthieu, K, Angela, N, Cuypers, Y, González-Santana, D, Forrer Heather, J, Grisoni, J, Grosso, O, Habasque, J, Jardin-Camps, M, Leblond, N, Le Moigne Frédéric, A, Lebourges-Dhaussy, A, Lory, C, Nunige, S, Pulido-Villena, E, Rizzo, A, Sarthou, G, Tilliette, C, 2. Bonnet Sophie, Guieu Cécile, Taillandier Vincent, Boulart Cédric, Bouruet-Aubertot Pascale, Gazeau Frédéric, Scalabrin Carla, Bressac Matthieu Knapp, Angela N., Cuypers Yannis, González-Santana David, Forrer Heather J., Grisoni Jean-Michel, Grosso Olivier, Habasque Jérémie, Jardin-Camps Mercedes, Leblond Nathalie, Le Moigne Frédéric A. C., Lebourges-Dhaussy Anne, Lory Caroline, Nunige Sandra, Pulido-Villena Elvira, Rizzo A, Sarthou Géraldine, Tilliette Chloé, 2., B, Guieu, C, Taillandier, V, Boulart, C, Bouruet-Aubertot, P, Gazeau, F, Scalabrin, C, Bressac Matthieu, K, Angela, N, Cuypers, Y, González-Santana, D, Forrer Heather, J, Grisoni, J, Grosso, O, Habasque, J, Jardin-Camps, M, Leblond, N, Le Moigne Frédéric, A, Lebourges-Dhaussy, A, Lory, C, Nunige, S, Pulido-Villena, E, Rizzo, A, Sarthou, G, Tilliette, C, 2. Bonnet Sophie, Guieu Cécile, Taillandier Vincent, Boulart Cédric, Bouruet-Aubertot Pascale, Gazeau Frédéric, Scalabrin Carla, Bressac Matthieu Knapp, Angela N., Cuypers Yannis, González-Santana David, Forrer Heather J., Grisoni Jean-Michel, Grosso Olivier, Habasque Jérémie, Jardin-Camps Mercedes, Leblond Nathalie, Le Moigne Frédéric A. C., Lebourges-Dhaussy Anne, Lory Caroline, Nunige Sandra, Pulido-Villena Elvira, Rizzo A, Sarthou Géraldine, and Tilliette Chloé

Abstract

Iron is an essential nutrient that regulates productivity in ~30% of the ocean. Compared with deep (>2000 meter) hydrothermal activity at mid-ocean ridges that provide iron to the ocean’s interior, shallow (<500 meter) hydrothermal fluids are likely to influence the surface’s ecosystem. However, their effect is unknown. In this work, we show that fluids emitted along the Tonga volcanic arc (South Pacific) have a substantial impact on iron concentrations in the photic layer through vertical diffusion. This enrichment stimulates biological activity, resulting in an extensive patch of chlorophyll (360,000 square kilometers). Diazotroph activity is two to eight times higher and carbon export fluxes are two to three times higher in iron-enriched waters than in adjacent unfertilized waters. Such findings reveal a previously undescribed mechanism of natural iron fertilization in the ocean that fuels regional hotspot sinks for atmospheric CO2.

Published
2023

18. Technical note: An autonomous flow-through salinity and temperature perturbation mesocosm system for multi-stressor experiments.

Author

Miller, Cale A., Urrutti, Pierre, Gattuso, Jean-Pierre, Comeau, Steeve, Lebrun, Anaïs, Alliouane, Samir, Schlegel, Robert W., and Gazeau, Frédéric

Subjects
MARINE heatwaves, TEMPERATURE control, SALINITY, ECOLOGICAL disturbances, TUNDRAS, TEMPERATURE
Abstract

The rapid environmental changes in aquatic systems as a result of anthropogenic forcings are creating a multitude of challenging conditions for organisms and communities. The need to better understand the interaction of environmental stressors now, and in the future, is fundamental to determining the response of ecosystems to these perturbations. This work describes an automated ex situ mesocosm perturbation system that can manipulate several variables of aquatic media in a controlled setting. This perturbation system was deployed in Kongsfjorden (Svalbard); within this system, ambient water from the fjord was heated and mixed with freshwater in a multifactorial design to investigate the response of mixed-kelp communities in mesocosms to projected future Arctic conditions. The system employed an automated dynamic offset scenario in which a nominal temperature increase was programmed as a set value above real-time ambient conditions in order to simulate future warming. A freshening component was applied in a similar manner: a decrease in salinity was coupled to track the temperature offset based on a temperature–salinity relationship in the fjord. The system functioned as an automated mixing manifold that adjusted flow rates of warmed and chilled ambient seawater, with unmanipulated ambient seawater and freshwater delivered as a single source of mixed media to individual mesocosms. These conditions were maintained via continuously measured temperature and salinity in 12 mesocosms (1 control and 3 treatments, all in triplicate) for 54 d. System regulation was robust, as median deviations from nominal conditions were < 0.15 for both temperature (∘ C) and salinity across the three replicates per treatment. Regulation further improved during a second deployment that mimicked three marine heat wave scenarios in which a dynamic temperature regulation held median deviations to < 0.036 ∘ C from the nominal value for all treatment conditions and replicates. This perturbation system has the potential to be implemented across a wide range of conditions to test single or multi-stressor drivers (e.g., increased temperature, freshening, and high CO 2) while maintaining natural variability. The automated and independent control for each experimental unit (if desired) provides a large breadth of versatility with respect to experimental design. [ABSTRACT FROM AUTHOR]

Published
2024
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20. Impact of climate change on Arctic macroalgal communities

Author

Lebrun Anaïs, Comeau Steeve, Gazeau Frédéric, and Gattuso Jean-Pierre

Subjects
Fucoids, Arctic, Kelps, Macroalgae, Climate change, Coralline algae
Abstract

The Arctic region faces a warming rate that is more than twice the global average. Sea-ice loss, increase in precipitation and freshwater discharge, changes in underwater light, and amplification of ocean acidification modify benthic habitats and the communities they host. Here, we synthesize existing information on the impacts of climate change on the macroalgal communities of Arctic coasts. We review the short- and long-term changes in environmental characteristics of shallow hard-bottomed Arctic coasts, the floristics of Arctic macroalgae (description, distribution, life-cycle, adaptations), the responses of their biological and ecological processes to climate change, the resulting winning and losing species, and the effects on ecosystem functioning. The focus of this review is on fucoid species, kelps, and coralline algae which are key ecosystem engineers in hard-bottom shallow areas of the Arctic, providing food, substrate, shelter, and nursery ground for many species. Changes in seasonality, benthic functional diversity, food-web structure, and carbon cycle are already occurring and are reshaping Arctic benthic ecosystems. Shallow communities are projected to shift from invertebrate- to algal-dominated communities. Fucoid and several kelp species are expected to largely spread and dominate the area with possible extinctions of native species. A considerable amount of functional diversity could be lost impacting the processing of land-derived nutrients and organic matter and significantly altering trophic structure and energy flow up to the apex consumers. However, many factors are not well understood yet, making it difficult to appreciate the current situation and predict the future coastal Arctic ecosystem. Efforts must be made to improve knowledge in key regions with proper seasonal coverage, taking into account interactions between stressors and across species.

Published
2022

22. A synthesis of SNAPO-CO2 ocean total alkalinity and total dissolved inorganic carbon measurements from 1993 to 2022.

Author

Metzl, Nicolas, Fin, Jonathan, Lo Monaco, Claire, Mignon, Claude, Alliouane, Samir, Antoine, David, Bourdin, Guillaume, Boutin, Jacqueline, Bozec, Yann, Conan, Pascal, Coppola, Laurent, Diaz, Frédéric, Douville, Eric, de Madron, Xavier Durrieu, Gattuso, Jean-Pierre, Gazeau, Frédéric, Golbol, Melek, Lansard, Bruno, Lefèvre, Dominique, and Lefèvre, Nathalie

Subjects
CARBON cycle, OCEAN, ALKALINITY, OCEAN acidification, POTENTIOMETRY, COASTS
Abstract

Total alkalinity (AT) and total dissolved inorganic carbon (CT) in the oceans are important properties to understand the ocean carbon cycle and its link with climate change (ocean carbon sinks and sources) or global change (ocean acidification). We present a data-base of more than 44 400 AT and CT observations in various ocean regions obtained since 1993 mainly in the frame of French projects. This includes both surface and water columns data acquired in open oceans, coastal zones and in the Mediterranean Sea and either from time-series or punctual cruises. Most AT and CT data in this synthesis were measured from discrete samples using the same closed-cell potentiometric titration calibrated with Certified Reference Material, with an overall accuracy of ± 4 µmol kg-1 for both AT and CT. Given the lack of observations in the Indian and Southern Oceans, we added sea surface underway AT and CT data obtained in 1998-2018 in the frame of OISO cruises and in 2019 during the CLIM-EPARSES cruise measured onboard using the same technique. Separate datasets for the global ocean, and for the Mediterranean Sea are provided in a single format (https://doi.org/10.17882/95414, Metzl et al., 2023) that offers a direct use for regional or global purposes, e.g. AT/Salinity relationships, long-term CT estimates, constraint and validation of diagnostics CT-AT reconstructed fields or ocean carbon and coupled climate/carbon models simulations, as well as data derived from BG-ARGO floats. When associated with other properties, these data can also be used to calculate pH, fugacity of CO2 (fCO2) and other carbon systems properties to derive ocean acidification rates or air-sea CO2 fluxes. [ABSTRACT FROM AUTHOR]

Published
2023
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23. Technical Note: An Autonomous Flow through Salinity and Temperature Perturbation Mesocosm System for Multi-stressor Experiments.

Author

Miller, Cale A., Urrutti, Pierre, Gattuso, Jean-Pierre, Comeau, Steeve, Lebrun, Anaïs, Alliouane, Samir, Schlegel, Robert W., and Gazeau, Frédéric

Subjects
ECOLOGICAL disturbances, SALINITY, COMMUNITIES, OCEAN temperature, TEMPERATURE
Abstract

The rapid environmental changes in aquatic systems as a result of anthropogenic forcings are creating a multitude of challenging conditions for organisms and communities. The need to better understand the interaction of environmental stressors now, and in the future, is fundamental to determining the response of ecosystems to these perturbations. This work describes an in situ mesocosm perturbation system that can manipulate aquatic media in a controlled setting on land. The employed system manipulated ambient water from Kongsfjorden, (Svalbard) by increasing temperature and freshening the seawater to investigate the response of mixed kelp communities to projected future Arctic conditions. This system manipulated temperature and salinity in real-time as an offset from incoming ambient seawater to conditions simulating future Arctic fjords. The system adjusted flow rates and mixing regimes of chilled, heated, ambient seawater, and freshwater, based on continuously measured conditions in a total of 12 mesocosms (1 ambient-control and 3 treatments, all in triplicates) for 54 days. System regulation was robust as median deviations from setpoint conditions were < 0.15 for both temperature (°C) and salinity across the 3 replicates per treatment. The implementation of this system has a wide range of versatility and can be deployed in a range of conditions to test single or multi-stressor conditions while maintaining natural variability. [ABSTRACT FROM AUTHOR]

Published
2023
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24. DFe patterns impacted by shallow hydrothermal sources along a transect through the Tonga-Kermadec arc

Author

Tilliette, Chloé, Taillandier, Vincent, Bouruet-aubertot, Pascale, Grima, Nicolas, Maes, Christophe, Montanes, Maryline, Sarthou, Geraldine, Vorrath, Maria-elena, Arnone, Veronica, Bressac, Matthieu, González-santana, David, Gazeau, Frédéric, Guieu, Cécile, Tilliette, Chloé, Taillandier, Vincent, Bouruet-aubertot, Pascale, Grima, Nicolas, Maes, Christophe, Montanes, Maryline, Sarthou, Geraldine, Vorrath, Maria-elena, Arnone, Veronica, Bressac, Matthieu, González-santana, David, Gazeau, Frédéric, and Guieu, Cécile

Abstract

In the Western Tropical South Pacific, a hotspot of N2-fixing organisms has recently been identified. The survival of these species depends on the availability of dissolved iron (dFe). dFe was measured along a transect from 175 °E to 166 °W near 19-21 °S. The distribution of dFe showed high spatial variability: low concentrations (~0.2 nmol kg-1) in the South Pacific gyre and high concentrations (up to 50 nmol kg-1) west of the Tonga arc, indicating that this arc is a clear boundary between iron-poor and iron-rich waters. An optimal multiparameter analysis was used to distinguish the relative importance of physical transport relative to non-conservative processes on the observed dFe distribution. This analysis demonstrated that distant sources of iron play a minor role in its distribution along the transect. The high concentrations observed were therefore attributed to shallow hydrothermal sources massively present along the Tonga-Kermadec arc. Nevertheless, in contrast to what has been observed for deep hydrothermal plumes, our results highlighted the rapid decrease in dFe concentrations near shallow hydrothermal sources. This is likely due to a shorter residence time of surface water masses combined with several biogeochemical processes at play (e.g., precipitation, photoreduction, scavenging, biological uptake). This study clearly highlights the role of shallow hydrothermal sources on the dFe cycle within the Tonga-Kermadec arc where a strong link to biological activity in surface waters can be assessed. It also emphasizes the need to consider the impact of these shallow hydrothermal sources for a better understanding of the global iron cycle.

Published
2022
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25. Revisiting tolerance to ocean acidification: insights from a new framework combining physiological and molecular tipping points of Pacific oyster

Author

Lutier, Mathieu, Di Poi Broussard, Carole, Gazeau, Frédéric, Appolis, Alexis, Le Luyer, Jeremy, Pernet, Fabrice, Lutier, Mathieu, Di Poi Broussard, Carole, Gazeau, Frédéric, Appolis, Alexis, Le Luyer, Jeremy, and Pernet, Fabrice

Abstract

Studies on the impact of ocean acidification on marine organisms involve exposing organisms to future acidification scenarios which has limited relevance for coastal calcifiers living in a mosaic of habitats. Identification of tipping points beyond which detrimental effects are observed is a widely generalizable proxy of acidification susceptibility at the populational level. This approach is limited to a handful of studies that focus on only a few macro-physiological traits, thus overlooking the whole organism response. Here we develop a framework to analyze the broad macro-physiological and molecular responses over a wide pH range in juvenile oyster. We identify low tipping points for physiological traits at pH 7.3-6.9 that coincide with a major reshuffling in membrane lipids and transcriptome. In contrast, a drop in pH affects shell parameters above tipping points, likely impacting animal fitness. These findings were made possible by the development of an innovative methodology to synthesize and identify the main patterns of variations in large -omic datasets, fitting them to pH and identifying molecular tipping-points. We propose the broad application of our framework to the assessment of effects of global change on other organisms.

Published
2022
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26. 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, Baudoux, Anne-claire, Dinasquet, Julie, Bigeard, Estelle, Gazeau, Frédéric, Azam, Farooq, Guieu, Cécile, Marañón, Emilio, Ridame, Céline, Van Wambeke, France, Obernosterer, Ingrid, and Baudoux, Anne-claire

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.

Published
2022
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27. Life-history traits in the Pacific oyster Crassostrea gigas are robust to ocean acidification under two thermal regimes

Author

Di poi, Carole, Brodu, Nicolas, Gazeau, Frédéric, Pernet, Fabrice, Di poi, Carole, Brodu, Nicolas, Gazeau, Frédéric, and Pernet, Fabrice

Abstract

Ocean acidification and warming (OAW) are pressing contemporary issues affecting marine life and specifically calcifying organisms. Here, we investigated the direct effects of OAW on life-history traits of the Pacific oyster Crassostrea gigas, the most cultivated bivalve species worldwide. We also tested whether parental conditioning history shaped the phenotypic characters of their progenies (intergenerational carryover effects). Adult oysters and their offspring were exposed to two temperatures (18°C, +3°C) under ambient pH conditions or under an end-of-century acidification scenario (−0.33 pH unit). In adults, we monitored standard biometric and reproductive parameters, stress response by quantifying neuroendocrine metabolites and gamete quality. In larvae, we measured hatching rate, size, biochemical quality, and behavior. We found that reducing pH reduced growth rate and activated the serotonin system, but increasing temperature attenuated these effects. There was no effect of pH on reproduction at either temperature, and no intergenerational carryover effects. Larval characteristics were similar between treatments, regardless of parental conditioning history. Thus, the Pacific oyster seems robust to changes in pH, and increasing temperature is not an aggravating factor. We emphasize that the use of neuroendocrine indicators holds promise for revealing sublethal impacts of environmental changes.

Published
2022
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28. 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

Centre National de la Recherche Scientifique (France), European Commission, Danish Council for Independent Research, Ridame, Céline, Dinasquet, Julie, Hallstrøm, Søren, Bigeard, Estelle, Riemann, Lasse, Wambeke, France van, Bressac, Matthieu, Pulido-Villena, Elvira, Taillandier, Vincent, Gazeau, Frédéric, Tovar-Sánchez, Antonio, Baudoux, Anne Claire, Guieu, Cécile, Centre National de la Recherche Scientifique (France), European Commission, Danish Council for Independent Research, Ridame, Céline, Dinasquet, Julie, Hallstrøm, Søren, Bigeard, Estelle, Riemann, Lasse, Wambeke, France van, Bressac, Matthieu, Pulido-Villena, Elvira, Taillandier, Vincent, Gazeau, Frédéric, Tovar-Sánchez, Antonio, Baudoux, Anne Claire, and Guieu, Cécile

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 fixatio

Published
2022

31. 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
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32. 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
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33. Chapitre 7

Author

Raimbault, Patrick, Boudouresque, Charles-François, Bănaru, Daniela, Jacquet, Stéphanie, Thibault, Delphine, Vincente, Nardo, Gazeau, Frédéric, Lemée, Rodolphe, Andral, Bruno, Galgani, François, Boissery, Pierre, and Lardic, Jean-Charles

Subjects
Méditerranée, changement climatique, climatologie, littoral, économie, mer, développement durable, Environmental Studies, espace urbain, sols, Marseille, environnement, biodiversité
Abstract

Introduction : le milieu marin face au changement global L’océan mondial occupe environ 71 % de la surface de la planète, dont à peine 1 % pour la mer Méditerranée. Encore largement incomplètement explorés, les océans sont considérés comme de véritables réservoirs de biodiversité dont 70 à 80 % resteraient à découvrir (Costello et al., 2010). Mais la biodiversité marine est déjà fortement dégradée par la surexploitation des ressources, la perte d’habitat, l’introduction d’espèces, le réchauff...

Published
2021

34. Marseille et l'environnement. Bilan, qualité et enjeux

Author

Affre, Laurence, Andral, Bruno, Arnaud, Patrick, Bănaru, Daniela, Bellier, Olivier, Boissery, Pierre, Boudouresque, Charles-François, Cann, Francis, Curt, Thomas, David, Bruno, Deschamps-Cottin, Magali, Galgani, François, Gazeau, Frédéric, Giraud, Xavier, Guiot, Joël, Jacquet, Stéphanie, Laffont-Schwob, Isabelle, Lardic, Jean-Charles, Lemée, Rodolphe, Mazurek, Hubert, Montes, Valérie, Peyras, Laurent, Raimbault, Patrick, Robert, Samuel, Robles, Christine, Thibault, Delphine, Tourment, Rémy, Vincente, Nardo, Guiot, Joël, Mazurek, Hubert, Curt, Thomas, and Raimbault, Patrick

Subjects
Méditerranée, changement climatique, climatologie, littoral, économie, mer, développement durable, Environmental Studies, espace urbain, sols, Marseille, environnement, biodiversité
Abstract

Aix-Marseille Provence, grande métropole située sur les bords de la Méditerranée, révèle de multiples questions sociales et environnementales. Cet ouvrage vise à questionner les enjeux du développement durable d’une telle métropole littorale méditerranéenne face au défi du changement climatique. Sur la base des connaissances scientifiques rassemblées au sein du collectif de recherche du Laboratoire d’Excellence OT-Med, cet ouvrage présente, dans une perspective interdisciplinaire, un état des lieux sur la problématique environnementale de cette métropole afin de répondre au mieux aux interrogations des gestionnaires et décideurs publics. On offre au lecteur une synthèse interdisciplinaire de « science locale » mise à la portée de tous : sont examinés l’espace urbain, les sols, la biodiversité, la mer et le littoral, l’atmosphère et la climatologie, les risques, les espaces protégés, etc. Référence académique mais aussi passerelle vers la société, l’économie et la gestion des milieux, ce livre a été conçu pour communiquer les données environnementales actuelles qui concernent Marseille au plus grand nombre et dans un langage accessible. Il permet de mieux connaître les défis actuels posés par le changement climatique, les actions déjà réalisées ou en cours, et les solutions encore à inventer.

Published
2021

35. Life-history traits in the Pacific oyster Crassostrea gigas are robust to ocean acidification under two thermal regimes.

Author

Di Poi, Carole, Brodu, Nicolas, Gazeau, Frédéric, and Pernet, Fabrice

Subjects
OCEAN acidification, LIFE history theory, CRASSOSTREA, PACIFIC oysters, MARINE biology, TEMPERATURE effect, PH effect, BROOD stock assessment
Abstract

Ocean acidification and warming (OAW) are pressing contemporary issues affecting marine life and specifically calcifying organisms. Here, we investigated the direct effects of OAW on life-history traits of the Pacific oyster Crassostrea gigas , the most cultivated bivalve species worldwide. We also tested whether parental conditioning history shaped the phenotypic characters of their progenies (intergenerational carryover effects). Adult oysters and their offspring were exposed to two temperatures (18°C, +3°C) under ambient pH conditions or under an end-of-century acidification scenario (−0.33 pH unit). In adults, we monitored standard biometric and reproductive parameters, stress response by quantifying neuroendocrine metabolites and gamete quality. In larvae, we measured hatching rate, size, biochemical quality, and behavior. We found that reducing pH reduced growth rate and activated the serotonin system, but increasing temperature attenuated these effects. There was no effect of pH on reproduction at either temperature, and no intergenerational carryover effects. Larval characteristics were similar between treatments, regardless of parental conditioning history. Thus, the Pacific oyster seems robust to changes in pH, and increasing temperature is not an aggravating factor. We emphasize that the use of neuroendocrine indicators holds promise for revealing sublethal impacts of environmental changes. [ABSTRACT FROM AUTHOR]

Published
2022
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36. Impact of dust addition on the metabolism of Mediterranean plankton communities and carbon export under present and future conditions of pH and temperature

Author

Gazeau, Frédéric, primary, Van Wambeke, France, additional, Marañón, Emilio, additional, Pérez-Lorenzo, Maria, additional, Alliouane, Samir, additional, Stolpe, Christian, additional, Blasco, Thierry, additional, Leblond, Nathalie, additional, Zäncker, Birthe, additional, Engel, Anja, additional, Marie, Barbara, additional, Dinasquet, Julie, additional, and Guieu, Cécile, additional

Published
2021
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37. 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
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38. 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, Baudoux, Anne-claire, Dinasquet, Julie, Bigeard, Estelle, Gazeau, Frédéric, Azam, Farooq, Guieu, Cécile, Marañón, Emilio, Ridame, Céline, Van Wambeke, France, Obernosterer, Ingrid, and Baudoux, Anne-claire

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.

Published
2021
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39. Impact of dust addition on the metabolism of Mediterranean plankton communities and carbon export under present and future conditions of pH and temperature

Author

Gazeau, Frédéric, Van Wambeke, France, Marañón, Emilio, Pérez-Lorenzo, Maria, Alliouane, Samir, Stolpe, Christian, Blasco, Thierry, Leblond, Nathalie, Zäncker, Birthe, Engel, Anja, Marie, Barbara, Dinasquet, Julie, Guieu, Cécile, Gazeau, Frédéric, Van Wambeke, France, Marañón, Emilio, Pérez-Lorenzo, Maria, Alliouane, Samir, Stolpe, Christian, Blasco, Thierry, Leblond, Nathalie, Zäncker, Birthe, Engel, Anja, Marie, Barbara, Dinasquet, Julie, and Guieu, Cécile

Abstract

Although atmospheric dust fluxes from arid as well as human-impacted areas represent a significant source of nutrients to surface waters of the Mediterranean Sea, studies focusing on the evolution of the metabolic balance of the plankton community following a dust deposition event are scarce, and none were conducted in the context of projected future levels of temperature and pH. Moreover, most of the experiments took place in coastal areas. In the framework of the PEACETIME project, three dust-addition perturbation experiments were conducted in 300 L tanks filled with surface seawater collected in the Tyrrhenian Sea (TYR), Ionian Sea (ION) and Algerian basin (FAST) on board the R/V Pourquoi Pas? in late spring 2017. For each experiment, six tanks were used to follow the evolution of chemical and biological stocks, biological activity and particle export. The impacts of a dust deposition event simulated at their surface were followed under present environmental conditions and under a realistic climate change scenario for 2100 (ca. +3 ∘C and −0.3 pH units). The tested waters were all typical of stratified oligotrophic conditions encountered in the open Mediterranean Sea at this period of the year, with low rates of primary production and a metabolic balance towards net heterotrophy. The release of nutrients after dust seeding had very contrasting impacts on the metabolism of the communities, depending on the station investigated. At TYR, the release of new nutrients was followed by a negative impact on both particulate and dissolved 14C-based production rates, while heterotrophic bacterial production strongly increased, driving the community to an even more heterotrophic state. At ION and FAST, the efficiency of organic matter export due to mineral/organic aggregation processes was lower than at TYR and likely related to a lower quantity/age of dissolved organic matter present at the time of the seeding and a smaller production of DOM following dust addition. This wa

Published
2021
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40. More than local adaptation: high diversity of response to seawater acidification in seven coral species from the same assemblage in French Polynesia

Author

Godefroid, Mathilde, Arçuby, Robin, Lacube, Yann, Espiau, Benoit, Dupont, Sam, Gazeau, Frédéric, Metian, Marc, Hédouin, Laetitia, Godefroid, Mathilde, Arçuby, Robin, Lacube, Yann, Espiau, Benoit, Dupont, Sam, Gazeau, Frédéric, Metian, Marc, and Hédouin, Laetitia

Abstract

Responses of corals to seawater acidification have been extensively studied. Sensitivity varies widely between species, highlighting the need to avoid extrapolation from one to another to get an accurate understanding of coral community responses. We tested the responses of seven coral species ( Acropora cytherea ,Acropora hyacinthus ,Acropora pulchra ,Leptastrea pruinosa ,Montipora grisea ,Pavona cactus ,Pocillopora verrucosa ) from the Mo'orea lagoon to a 48-day exposure to three pH scenarios (pH 7.95, 7.7 and 7.3). Tissue necrosis, mortality, growth rates, photophysiological performances and colour index were recorded. Few significant differences were noted between pH 7.95 and 7.7, but species-specific responses were observed at pH 7.3. While our data do not allow identification of the mechanisms behind this diversity in response between species inhabiting the same environment, it can exclude several hypotheses such as local adaptation, skeletal type, corallum morphology or calcification rate as sole factors determining coral sensitivity to pH., info:eu-repo/semantics/published

Published
2021

43. 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, Roy-barman, Matthieu, Foliot, Lorna, Douville, Eric, Leblond, Nathalie, Gazeau, Frédéric, Bressac, Matthieu, Wagener, Thibaut, Ridame, Céline, Desboeufs, Karine, and Guieu, Cécile

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 232Th 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 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 thorium and REE in seawater, leading to a lower Th release and a higher light REE release under increased greenhouse conditions.

Published
2020
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44. Biochemical dataset collected during the Peacetime cruise

Author

Schmechtig, Catherine [schmechtig@obs-vlfr.fr], Guieu, Cécile, Desboeufs, Karine, Albani, Samuel, Alliouane, Samir, Aumont, Olivier, Barbieux, Marie, Barrillon, Stéphanie, Baudoux, Anne Claire, Berline, Léo, Bhairy, Nahib, Bigeard, Estelle, Bloss, Matthew, Bressac, Matthieu, Brito, J., Carlotti, François, Liege, Guillaume de, Dinasquet, Julie, Djaoudi, Kahina, Doglioli, Andrea M., D'Ortenzio, Fabrizio, Doussin, Jean François, Duforet, Lucile, Dulac, François, Dutay, Jean Claude, Engel, Anja, Feliú-Brito, Guillermo, Ferre, Hélène, Formenti, Paula, Fu, Franck, García, David, Garel, Marc, Gazeau, Frédéric, Giorio, Chiara, Gregori, Gérald, Grisoni, Jean Michel, Guasco, Sophie, Guittonneau, Joris, Haëntjens, Nils, Heimburger, Lars Eric, Helias, Sandra, Jacquet, Stéphanie H. M., Laurent, Brice, Leblond, Nathalie, Lefevre, Dominique, Mallet, Marc, Marañón, Emilio, Nabat, Pierre, Nicosia, Alessia, Obernosterer, Ingrid, Pérez-Lorenzo, María, Petrenko, Anne, Pulido-Villena, Elvira, Raimbault, Patrick, Ridame, Céline, Riffault, Véronique, Rougier, Gilles, Rousselet, Louise, Roy-Barman, Matthieu, Saiz-Lopez, A., Schmechtig, Catherine, Sellegri, Karine, Siour, Guillaume, Taillandier, Vincent, Tamburini, Christian, Thyssen, Melilotus, Tovar-Sánchez, Antonio, Triquet, Sylvain, Uitz, Julia, Wambeke, France van, Wagener, Thibaut, Zaencker, Birthe, Schmechtig, Catherine [schmechtig@obs-vlfr.fr], Guieu, Cécile, Desboeufs, Karine, Albani, Samuel, Alliouane, Samir, Aumont, Olivier, Barbieux, Marie, Barrillon, Stéphanie, Baudoux, Anne Claire, Berline, Léo, Bhairy, Nahib, Bigeard, Estelle, Bloss, Matthew, Bressac, Matthieu, Brito, J., Carlotti, François, Liege, Guillaume de, Dinasquet, Julie, Djaoudi, Kahina, Doglioli, Andrea M., D'Ortenzio, Fabrizio, Doussin, Jean François, Duforet, Lucile, Dulac, François, Dutay, Jean Claude, Engel, Anja, Feliú-Brito, Guillermo, Ferre, Hélène, Formenti, Paula, Fu, Franck, García, David, Garel, Marc, Gazeau, Frédéric, Giorio, Chiara, Gregori, Gérald, Grisoni, Jean Michel, Guasco, Sophie, Guittonneau, Joris, Haëntjens, Nils, Heimburger, Lars Eric, Helias, Sandra, Jacquet, Stéphanie H. M., Laurent, Brice, Leblond, Nathalie, Lefevre, Dominique, Mallet, Marc, Marañón, Emilio, Nabat, Pierre, Nicosia, Alessia, Obernosterer, Ingrid, Pérez-Lorenzo, María, Petrenko, Anne, Pulido-Villena, Elvira, Raimbault, Patrick, Ridame, Céline, Riffault, Véronique, Rougier, Gilles, Rousselet, Louise, Roy-Barman, Matthieu, Saiz-Lopez, A., Schmechtig, Catherine, Sellegri, Karine, Siour, Guillaume, Taillandier, Vincent, Tamburini, Christian, Thyssen, Melilotus, Tovar-Sánchez, Antonio, Triquet, Sylvain, Uitz, Julia, Wambeke, France van, Wagener, Thibaut, and Zaencker, Birthe

Abstract

The general objective of the PEACETIME cruise is to study the fundamental processes and their interactions at the ocean-atmosphere interface, occurring after atmospheric deposition (especially Saharan dust) in the Mediterranean Sea, and how these processes impact the functioning of the pelagic ecosystem. During the proposed 33 days cruise in the western and central Mediterranean Sea in May 2017, we will study the impact of atmospheric deposition on the cycles of chemical elements, on marine biogeochemical processes and fluxes, on marine aerosols emission and how ongoing changes will impact the functioning of Mediterranean Sea communities in the future. The cruise is designed to explore a variety of oligotrophic regimes. Combining in situ observations both in the atmosphere and the ocean, and in situ and minicosm-based on-board process studies, the 40 embarking scientists from atmosphere and ocean sciences will characterize the chemical, biological and physical/optical properties of both the atmosphere and the sea-surface microlayer, mixed layer and deeper waters. The PEACETIME strategy (season and cruise track) associated to a combination of dust transport forecasting tools and near real-time satellite remote sensing is designed to maximize the probability to catch a Saharan dust deposition event in a stratified water column in order to follow the associated processes in-situ. This coordinated multidisciplinary effort will allow us to fill the current weaknesses/lacks in our knowledge of atmospheric deposition impact in the ocean and feedbacks to the atmosphere in such oligotrophic systems. As a key joint-project between MERMEX and CHARMEX : The PEACETIME project comes in the scope of the regional multidisciplinaryprogramme MISTRALS (Mediterranean Integrated STudies at Regional And Local Scales ), which aims at predicting the evolution of this region following strong expected changes in climate and human pressures. In this framework, the PEACETIME project constitute

Published
2020

45. 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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46. 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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47. Coastal ocean acidification and increasing total alkalinity in the northwestern Mediterranean Sea

Author

Kapsenberg, Lydia, Alliouane, Samir, Gazeau, Frédéric, Mousseau, Laure, Gattuso, Jean-Pierre, 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), Institute for Sustainable Development and International Relations, and Sciences Po (Sciences Po)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract

International audience; Coastal time series of ocean carbonate chemistry are critical for understanding how global anthropogenic change manifests in near-shore ecosystems. Yet, they are few and have low temporal resolution. At the time series station Point B in the northwestern Mediterranean Sea, seawater was sampled weekly from 2007 through 2015, at 1 and 50 m, and analyzed for total dissolved inorganic carbon (C T) and total alkalinity (A T). Parameters of the carbonate system such as pH (pH T , total hydrogen ion scale) were calculated and a deconvolution analysis was performed to identify drivers of change. The rate of surface ocean acidification was −0.0028 ± 0.0003 units pH T yr −1. This rate is larger than previously identified open-ocean trends due to rapid warming that occurred over the study period (0.072 ± 0.022 • C yr −1). The total pH T change over the study period was of similar magnitude as the diel pH T variability at this site. The acidification trend can be attributed to atmospheric carbon dioxide (CO 2) forcing (59 %, 2.08 ± 0.01 ppm CO 2 yr −1) and warming (41 %). Similar trends were observed at 50 m but rates were generally slower. At 1 m depth, the increase in atmospheric CO 2 accounted for approximately 40 % of the observed increase in C T (2.97 ± 0.20 µmol kg −1 yr −1). The remaining increase in C T may have been driven by the same unidentified process that caused an increase in A T (2.08 ± 0.19 µmol kg −1 yr −1). Based on the analysis of monthly trends, synchronous increases in C T and A T were fastest in the spring–summer transition. The driving process of the interannual increase in A T has a seasonal and shallow component, which may indicate riverine or groundwater influence. This study exemplifies the importance of understanding changes in coastal carbonate chemistry through the lens of biogeochemical cycling at the land–sea interface. This is the first coastal acidification time series providing multi-year data at high temporal resolution. The data confirm rapid warming in the Mediterranean Sea and demonstrate coastal acidification with a synchronous increase in total alkalinity.

Published
2017
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48. Experimental evidence of formation of transparent exopolymer particles (TEP) and POC export provoked by dust addition under current and high pCO2 conditions

Author

Louis, Justine, Pedrotti, Maria Luiza, Gazeau, Frédéric, Guieu, Cécile, Département Génie Biologique / IUT de Saint-Brieuc, Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), 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), IUT de Saint-Brieuc, Université de Rennes (UR), and 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)

Subjects
Atmospheric Science, Carbon Sequestration, Environmental Engineering, Materials by Structure, Polymers, Materials Science, lcsh:Medicine, Oceanography, Sea Water, Bodies of water, Oceans, Mediterranean Sea, Pressure, Environmental Chemistry, Seawater, Organic Chemicals, Particle Size, lcsh:Science, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Petrology, Sedimentary Geology, Ocean Acidification, Ecology and Environmental Sciences, lcsh:R, Dust, Geology, Carbon Dioxide, Hydrogen-Ion Concentration, Marine and aquatic sciences, Chemistry, Particulates, Atmospheric Chemistry, Mixtures, Physical Sciences, Earth Sciences, Engineering and Technology, Sediment, lcsh:Q, Antacids, Hydrology, Acid Deposition, Research Article
Abstract

International audience; The evolution of organic carbon export to the deep ocean, under anthropogenic forcing such as ocean warming and acidification, needs to be investigated in order to evaluate potential positive or negative feedbacks on atmospheric CO 2 concentrations, and therefore on climate. As such, modifications of aggregation processes driven by transparent exopolymer particles (TEP) formation have the potential to affect carbon export. The objectives of this study were to experimentally assess the dynamics of organic matter, after the simulation of a Saharan dust deposition event, through the measurement over one week of TEP abundance and size, and to evaluate the effects of ocean acidification on TEP formation and carbon export following a dust deposition event. Three experiments were performed in the laboratory using 300 L tanks filled with filtered seawater collected in the Mediterranean Sea, during two 'no bloom' periods (spring at the start of the stratification period and autumn at the end of this stratification period) and during the winter bloom period. For each experiment, one of the two tanks was acidified to reach pH conditions slightly below values projected for 2100 (~ 7.6–7.8). In both tanks, a dust deposition event of 10 g m-2 was simulated at the surface. Our results suggest that Saharan dust deposition triggered the abiotic formation of TEP, leading to the formation of organic-mineral aggregates. The amount of particulate organic carbon (POC) exported was proportional to the flux of lithogenic particles to the sediment traps. Depending on the season, the POC flux following artificial dust deposition ranged between 38 and 90 mg m-2 over six experimental days. Such variability is likely linked to the seasonal differences in the quality and quantity of TEP-precursors initially present in seawater. Finally, these export fluxes were not significantly different at the completion of the three experiments between the two pH conditions.

Published
2017
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49. Intercomparison of four methods to estimate coral calcification under various environmental conditions.

Author

Batista, Miguel Gómez, Metian, Marc, Oberhänsli, François, Pouil, Simon, Swarzenski, Peter W., Tambutté, Eric, Gattuso, Jean-Pierre, Hernández, Carlos M. Alonso, and Gazeau, Frédéric

Subjects
CALCIFICATION, CORAL reef ecology, CORALS, ECOSYSTEM health, OCEAN acidification, CALCIUM carbonate, ALKALINITY
Abstract

Coral reefs are constructed by calcifiers that precipitate calcium carbonate to build their shells or skeletons through the process of calcification. Accurately assessing coral calcification rates is crucial to determine the health of these ecosystems and their response to major environmental changes such as ocean warming and acidification. Several approaches have been used to assess rates of coral calcification but there is a real need to compare these approaches in order to ascertain that high quality and intercomparable results can be produced. Here, we assessed four methods (total alkalinity anomaly, calcium anomaly, 45Ca incorporation and 13C incorporation) to determine coral calcification of the reef-building coral Stylophora pistillata. Given the importance of environmental conditions on this process, the study was performed under two pH (ambient and low level) and two light (light and dark) conditions. Under all conditions, calcification rates estimated using the alkalinity and calcium anomaly techniques as well as 45Ca incorporation were highly correlated. Such a strong correlation between the alkalinity anomaly and 45Ca incorporation techniques has not been observed in previous studies and most probably results from improvements described in the present paper. The only method which provided calcification rates significantly different from the other three techniques was 13C incorporation. Calcification rates based on this method were consistently higher than those measured using the other techniques. Although reasons for these discrepancies remain unclear, the use of this technique for assessing calcification rates in corals is not recommended without further investigations. [ABSTRACT FROM AUTHOR]

Published
2019
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50. Free-ocean CO 2 enrichment (FOCE) systems: present status and future developments

Author

Gattuso, Jean-Pierre, Kirkwood, W, Barry, J.P, Cox, E, Gazeau, Frédéric, Hansson, L, Hendriks, I, Kline, D.I., Mahacek, P, Martin, Sophie, Mcelhany, P., Peltzer, E.T., Reeve, J, Roberts, D, Saderne, V, Tait, K, Widdicombe, S, Brewer, P.G., Observatoire océanologique de Villefranche-sur-mer (OOVM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Monterey Bay Aquarium Research Institute (MBARI), Monterey Bay Aquarium Research Institute, 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), Ocean Acidification International Coordination Centre, Global Change Department (IMEDEA (CSIC-UIB)), Institut Mediterrani d'Estudis Avancats (IMEDEA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Universidad de las Islas Baleares (UIB)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Universidad de las Islas Baleares (UIB), Scripps Institute of Oceanography, University of California [San Diego] (UC San Diego), University of California-University of California, Ecogéochimie et Fonctionnement des Ecosystèmes Benthiques (EFEB), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff [Roscoff] (SBR), 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)-Station biologique de Roscoff [Roscoff] (SBR), 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), Conservation Biology Division [Seattle], Northwest Fisheries Science Center (NWFSC), NOAA National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA)-NOAA National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA), Department of the environment, Channel Highway, Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), Benthic Ecology group (GEOMAR), Plymouth Marine Laboratory (PML), Plymouth Marine Laboratory, 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)-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), Scripps Institution of Oceanography (SIO - UC San Diego), and University of California (UC)-University of California (UC)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry
Abstract

International audience; Free-ocean CO2 enrichment (FOCE) systems are designed to assess the impact of ocean acidification on biological communities in situ for extended periods of time (weeks to months). They overcome some of the drawbacks of laboratory experiments and field observations by enabling (1) precise control of CO2 enrichment by monitoring pH as an offset of ambient pH, (2) consideration of indirect effects such as those mediated through interspecific relationships and food webs, and (3) relatively long experiments with intact communities. Bringing perturbation experiments from the laboratory to the field is, however, extremely challenging. The main goal of this paper is to provide guidelines on the general design, engineering, and sensor options required to conduct FOCE experiments. Another goal is to introduce xFOCE, a community-led initiative to promote awareness, provide resources for in situ perturbation experiments, and build a user community. Present and existing FOCE systems are briefly described and examples of data collected presented. Future developments are also addressed as it is anticipated that the next generation of FOCE systems will include, in addition to pH, options for oxygen and/or temperature control. FOCE systems should become an important experimental approach for projecting the future response of marine ecosystems to environmental change.

Published
2014
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