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31 results on '"ISBlue - Interdisciplinary Graduate School for the Blue planet (2017)"'

1. Marine and subaerial controls of coastal chalk cliff erosion in Normandy (France) based on a 7-year laser scanner monitoring

Author

Pauline Letortu, Robert Davidson, Olivier Maquaire, Stéphane Costa, Littoral, Environnement, Télédétection, Géomatique (LETG - Brest), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), Littoral, Environnement, Télédétection, Géomatique (LETG - Caen), 17-EURE-0015 - ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), and ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)

Subjects
Terrestrial laser scanning, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SHS.GEO]Humanities and Social Sciences/Geography, Cliff erosion, 010502 geochemistry & geophysics, 01 natural sciences, Current (stream), 13. Climate action, Subaerial, Cliff, Erosion, Subaerial processes, 14. Life underwater, Physical geography, Geology, Marine processes, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

International audience; Between October 2010 and November 2017, surveys using terrestrial laser scanning (TLS) were carried out every 4-5 months to monitor erosion on three chalk cliff faces with close structural characteristics in Normandy (the two Dieppe sites are abandoned cliffs while the Varengeville-sur-Mer site is an active one). The uniqueness of this paper is the comparison between these cliff sections and the significance of marine and/or subaerial controls in erosion. Beyond the quantification of annual retreat rates, which on the active cliff are currently 36 times greater than on the abandoned cliffs, this paper highlights the fundamental efficacy of marine controls in the current cliff erosion and the removal of falls (analyses of modalities of retreat and profile evolution according to a naturalistic approach). Subaerial processes appear to have a less erosive action than marine ones, because the studied abandoned cliffs show low erosion dynamics and have maintained a subvertical profile despite continentalization for between 30 to more than 120 years.

Published
2019
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2. Linking Spatial and Temporal Dynamic of Bacterioplankton Communities With Ecological Strategies Across a Coastal Frontal Area

Author

Lemonnier, Clarisse, Perennou, Morgan, Eveillard, Damien, Fernandez-Guerra, Antonio, Leynaert, Aude, Marié, Louis, Morrison, Hilary, Mémery, Laurent, Paillard, Christine, Maignien, Lois, Laboratoire de microbiologie des environnements extrêmophiles (LM2E), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Numériques de Nantes (LS2N), Microbial genomics and bioinformatics research group, Max Planck Institute for Marine Microbiology, Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Lundbeck Foundation GeoGenetics Center, Center for Marine Environmental Sciences [Bremen] (MARUM), Universität Bremen, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Marine Biological Laboratory (MBL), University of Chicago, This work was supported by the 'Laboratoire d’Excellence' LabexMER (ANR-10-LABX-19) and co-funded by a grant from the French government under the program 'Investissements d’Avenir,' and the Regional Council of Brittany. It was also supported by the University of Western Brittany (UBO)., ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Numérique de Nantes (LS2N), IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Combinatoire et Bioinformatique (COMBI), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), and ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)

Subjects
dynamic, USHANT TIDAL FRONT, SUCCESSION, [SDV]Life Sciences [q-bio], [INFO.INFO-OH]Computer Science [cs]/Other [cs.OH], fungi, GENOME SEQUENCE, BRITTANY, bacterial communities, [SDV.BIBS]Life Sciences [q-bio]/Quantitative Methods [q-bio.QM], ecological strategies, VARIABILITY, PHYTOPLANKTON, network, PATTERNS, ECOSYSTEM, MICROBES, [INFO.INFO-BI]Computer Science [cs]/Bioinformatics [q-bio.QM], marine front, ComputingMilieux_MISCELLANEOUS, [SDV.EE.IEO]Life Sciences [q-bio]/Ecology, environment/Symbiosis
Abstract

Ocean frontal systems are widespread hydrological features defining the transition zone between distinct water masses. They are generally of high biological importance as they are often associated with locally enhanced primary production by phytoplankton. However, the composition of bacterial communities in the frontal zone remains poorly understood. In this study, we investigate how a coastal tidal front in Brittany (France) structures the free-living bacterioplankton communities in a spatio-temporal survey across four cruises, five stations and three depths. We used 16S rRNA gene surveys to compare bacterial community structures across 134 seawater samples and defined groups of co-varying taxa (modules) exhibiting coherent ecological patterns across space and time. We found that bacterial communities composition was strongly associated with the biogeochemical characteristics of the different water masses and that the front act as an ecological boundary for free-living bacteria. Seasonal variations in primary producers and their distribution in the water column appeared as the most salient parameters controlling heterotrophic bacteria which dominated the free-living community. Different dynamics of modules observed in this environment were strongly consistent with a partitioning of heterotrophic bacterioplankton in oligotroph and copiotroph ecological strategies. Oligotroph taxa, dominated by SAR11 Clade members, were relatively more abundant in low phytoplankton, high inorganic nutrients water masses, while copiotrophs and particularly opportunist taxa such as Tenacibaculum sp. or Pseudoalteromonas sp. reached their highest abundances during the more productive period. Overall, this study shows a remarkable coupling between bacterioplankton communities dynamics, trophic strategies, and seasonal cycles in a complex coastal environment.

Published
2020
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3. Social Networks of Alaska Fishing Communities

Author

Anna Lavoie, Amber Himes-Cornell, Alaska Fisheries Science Center (AFSC), NOAA National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA), Aménagement des Usages des Ressources et des Espaces marins et littoraux - Centre de droit et d'économie de la mer (AMURE), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, Adaptive capacity, Business transactions, 010504 meteorology & atmospheric sciences, Fishing communities, 010604 marine biology & hydrobiology, media_common.quotation_subject, Fishing, 01 natural sciences, Social networks, [SDE]Environmental Sciences, Environmental Chemistry, 14. Life underwater, Business, Function (engineering), Alaska, Industrial organization, 0105 earth and related environmental sciences, General Environmental Science, media_common
Abstract

International audience; Fishing community social networks function as channels for transfer of fishery knowledge, resources, and business transactions that help mitigate risks and shocks associated with altered access to fishery resources. Research on such networks in Alaska is limited despite their cultural importance and community reliance on fisheries. We contribute to scholarship of fishery social networks by assessing Alaska fishing community perspectives of challenges related to fisheries policy and management, and the existing social networks that aid in overcoming these challenges. Our findings show that the greatest challenges fishing communities face pertaining to fishery management are high costs of participating in catch share programs, restricted subsistence fishing activity due to decline in salmon, and complex regulations. Social networks exist for coping with these challenges; fishery information, and resources such as food, fuel and medicines are shared between communities. However, networks for accessing fishery support services are centralized in fewer larger communities and hubs such as Anchorage. Smaller and remote communities are the most compromised in this regard given the distance they must travel to access fishery support services. Leveraging social networks for sharing resources and improving fishery support services in smaller communities will increase their adaptive capacity and ability to maintain participation in Alaska fisheries.

Published
2019
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4. Simulating sediment supply from the Congo watershed over the last 155 ka

Author

Laurence Droz, Dimitri Laurent, Marina Rabineau, Guy Dieudonne Moukandi N’Kaya, Albert J. Kettner, Stéphane Molliex, Alain Laraque, Tania Marsset, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire des Mécanismes et Transfert en Géologie (LMTG), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Colorado [Boulder], Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Géosciences Marines (GM), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Marien Ngouabi, ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Sediment supply modeling, HydroTrend, 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, Floodplain, Weathering, Equatorial Africa, Drainage basin, Fluvial, Land cover, 01 natural sciences, Vegetation dynamics, Hydrology (agriculture), Glacial/interglacial, Glacialinterglacial, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 14. Life underwater, Glacial period, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Hydrology, Global and Planetary Change, geography, geography.geographical_feature_category, Congo watershed, Sediment, Geology, 15. Life on land, 13. Climate action, Interglacial, Environmental science, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology
Abstract

The Congo River is the world's second largest river in terms of drainage area and water discharge. Monitored for decades, a large dataset is available, onshore for both the hydrology and sediment load, and offshore by many paleo-environmental proxies compiled at the Late-Quaternary time-scale. These numerous data allow for accurate calibration of numerical modeling. In this study, we aim to numerically quantify the evolution of sediment supply leaving the tropical Congo watershed during the last 155 ka and to decipher the forcing parameters that control this sediment supply over glacial/interglacial stages. For this, a modified version of the model HydroTrend, that besides morphologic, climatic, hydrologic, lithologic, land cover and anthropogenic factors now also considers sediment deposition on the floodplain, is used. In addition, a method to quantify the impact of natural vegetation changes is developed. Simulations match well the present-day observed data. They indicate that a significant portion of suspended sediments is trapped on the floodplain. Long-term simulations indicate that environmental changes between glacial and interglacial stages account for a 30% maximum variation of sediment supply. Climatic changes - precipitation and temperature, account for a maximum decrease in sediment supply of 20% during cold periods while conversely, induced land cover changes (loss of forest during colder and dryer stages) lead to enhanced sediment supply up to 30%. Over a longer period, the average sediment supply remained almost constant during glacial and interglacial periods, while peaks may have occurred during a warming period, just before forests had time to recover the catchment, i.e. during post-glacial periods. These moderate changes in sediment export, despite major changes in climate and vegetation cover, can be explained by the efficiency of sediment trapping of large tropical catchments that buffer fluvial fluxes towards the ocean.

Published
2019
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5. Conceptual advances on global scale assessments of vulnerability: Informing investments for coastal populations at risk of climate change

Author

Adrien Comte, Denis Bailly, Emmanuelle Quillérou, Linwood Pendleton, Aménagement des Usages des Ressources et des Espaces marins et littoraux - Centre de droit et d'économie de la mer (AMURE), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Duke University [Durham], ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), and ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)

Subjects
0106 biological sciences, Prioritizing investments, Economics and Econometrics, Vulnerability index, Environmental change, Vulnerability, Climate change, Management, Monitoring, Policy and Law, Aquatic Science, 01 natural sciences, Marine and coastal areas, Effects of global warming, Vulnerability assessment, Environmental planning, General Environmental Science, Adaptive capacity, Operationalization, Conceptual frameworks, 010604 marine biology & hydrobiology, 04 agricultural and veterinary sciences, Global assessments, Geography, 13. Climate action, [SDE]Environmental Sciences, 040102 fisheries, 0401 agriculture, forestry, and fisheries, Law
Abstract

International audience; Since the 1990s, the Intergovernmental Panel on Climate Change (IPCC) has used global assessments of vulnerability to inform investment and action against the effects of climate change. Beyond the IPCC, others have undertaken global assessments to understand the vulnerability of coastal areas to climate change. Eight global vulnerability assessments are compared to understand similarities and differences in their results and the metrics used to construct a vulnerability index. Variations in objectives, conceptualizations of vulnerability, operationalization of the concepts, scope and depth of data drawn upon lead to contradictory rankings of priority areas for climate action between assessments. The increased complexity and scope of indicators make it difficult to untangle the root causes of such differences in rankings. It is also difficult to identify the degree to which climate change influences vulnerability rankings compared to other factors such as local environmental conditions and the capacity of populations to deal with environmental change. The way to undertake global assessments needs to be reshaped to better inform planning of international development along different objectives. Global level assessments need to be simplified and harmonized to better isolate the impact of climate change specific drivers. Decision-makers would make better use of such global assessments as scoping studies rather than expect comprehensive and robust priorities for investment. Such scoping studies can help target locations where supplementary, in-depth local analyses need to be conducted. At the local level, the possibility to collect context-specific information, particularly on adaptive capacity, allows the robust assessment of vulnerability.

Published
2019
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6. Discovery of buried historical structures in the Kaveri-Kollidam interfluve, southern India

Author

K. Balasubramani, E. Manikandan, S. Abdul Rahaman, Mu. Ramkumar, A. Balasundareshwaran, David Menier, G. Prithiviraj, C. Ramachandran, Ramasamy Nagarajan, U. Kumara Ganesh, Numair Ahmed Siddiqui, R. Ayyanthurai, Manoj Joseph Mathew, M. Santosh, K. Kumaraswamy, R. Jegankumar, M. Sathyaseelan, P. Sivakumar, Periyar University, Bharathidasan University [Tiruchirappalli, India], Department of Geography, Central University of Tamil Nadu, Faculty of Science - Japan, Curtin University, Sarawak Malaysia, Universiti Teknologi PETRONAS (UTP), Faculty of Geosciences and petroleum Engineering, Universiti Tecknologi Petronas, Laboratoire Géosciences Océan (LGO), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Department of Mechanical Engineering, Vickram College of Engineering, ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), and Université de Brest (UBO)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)

Subjects
geophysical explorationg, Archeology, History, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, 010504 meteorology & atmospheric sciences, Exploration geophysics, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Geoarchaeology, ground‐penetrating radar, India, 15. Life on land, catastrophic floods, 010502 geochemistry & geophysics, 01 natural sciences, Paleontology, Kaveri River, Ground-penetrating radar, buried sites, geoarchaeology, Geology, 0105 earth and related environmental sciences
Abstract

International audience; The Srirangam interfluve, formed between the Kaveri and Kollidam Rivers in southern India, has been a religious and cultural human settlement for over 2000 years of recorded history. It contains thousands of ancient, yet in use, man‐made structures. Owing to its geographic location, and episodic catastrophic floods from the Kaveri and Kollidam Rivers, the region has been inundated frequently leading to the burial of many smaller structures. Thematic maps of geomorphology, vegetation index, land use, digital elevation model, slope, etc., have been generated through multi‐temporal remote sensing satellite images. A compilation of historic (stone inscriptions, temple documents) and literature data followed by detailed survey of the region using vertical electrical sounding (VES) and ground‐penetrating radar (GPR) through 200 and 400 MHz shielded antennas has led to the discovery of several buried manmade structures at various depths ranging from 0.54 to 3.55 m below ground level (b.g.l.) that were known only in the literature, hearsay and folklore. The VES, GPR and field surveys delineated four major soil/sediment horizons below the ground surface. Sedimentological characteristics of a massive river sand bed found overlying a weathered zone suggest deposition during a major catastrophic flood. The occurrence of flood deposits burying historic structures especially adjoining the regional tectonic structure indicate episodically active climatic and tectonic processes that played a significant role in the burial of ancient‐historic land surface and manmade structures that were under desolation after invasion and desecration by war‐lords of yore. This study demonstrates the potential of combining traditional knowledge and modern technologies to gain insights to locate historic/archaeological sites and discover buried structures.

Published
2018
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7. The toxic dinoflagellate Alexandrium minutum impairs the performance of oyster embryos and larvae

Author

Hélène Hégaret, Myrina Boulais, Caroline Fabioux, Matthias Huber, Justine Castrec, Arnaud Huvet, Kevin Tallec, Philippe Soudant, Jacqueline Le Grand, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, Paralytic Shellfish Toxin (PST), Oyster, animal structures, Population, Zoology, embryo, larvae, Plant Science, 010501 environmental sciences, Aquatic Science, 01 natural sciences, bivalve, biology.animal, parasitic diseases, medicine, Animals, Harmful Algal Bloom (HAB), 14. Life underwater, Crassostrea, education, Shellfish, health care economics and organizations, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Larva, education.field_of_study, [SDV.BA.MVSA]Life Sciences [q-bio]/Animal biology/Veterinary medicine and animal Health, biology, 010604 marine biology & hydrobiology, fungi, Dinoflagellate, food and beverages, Pacific oyster, biology.organism_classification, medicine.disease, Shellfish poisoning, Bioactive Extracellular Compounds (BEC), Crassostrea gigas, Dinoflagellida, Marine Toxins, France, [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology
Abstract

International audience; The dinoflagellate genus Alexandrium comprises species that produce highly potent neurotoxins known as paralytic shellfish toxins (PST), and bioactive extracellular compounds (BEC) of unknown structure and ecological significance. The toxic bloom-forming species, Alexandrium minutum, is distributed worldwide and adversely affects many bivalves including the commercially and ecologically important Pacific oyster, Crassostrea gigas. In France, recurrent A. minutum blooms can co-occur with C. gigas spawning and larval development, and may endanger recruitment and population renewal. The present study explores how A. minutum affects early-oyster development by exposing embryos and larvae, under controlled laboratory conditions, to two strains of A. minutum, producing only BEC or both PST and BEC. Results highlight the major role of BEC in A. minutum toxicity upon oyster development. The BEC strain caused lysis of embryos, the most sensitive stage to A. minutum toxicity among planktonic life-stages. In addition, the non-PST-producing A. minutum strain inhibited hatching, disrupted larval swimming behavior, feeding, growth, and induced drastic decreases in survival and settlement of umbonate and eyed larvae (9 and 68 %, respectively). The findings indicated PST accumulation in oyster larvae (e.g. umbonate stages), possibly impairing development and settlement of larvae in response to the PST-producing strain. This work provides evidences that A. minutum blooms could hamper settlement of shellfish.

Published
2020
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8. COMBINED EFFECTS OF TEMPERATURE, IRRADIANCE AND PH ON TELEAULAX AMPHIOXEIA (CRYPTOPHYCEAE) PHYSIOLOGY AND FEEDING RATIO FOR ITS PREDATOR MESODINIUM RUBRUM (CILIOPHORA)

Author

Gaillard, Sylvain, Charrier, Aurélie, Malo, Florent, carpentier, liliane, Bougaran, Gaël, Hegaret, Helene, Réveillon, Damien, Hess, Philipp, Sechet, Véronique, Laboratoire Phycotoxines, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Physiologie et Biotechnologie des Algues (PBA), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Laboratoire Phycotoxines (PHYC), Dynamiques des Écosystèmes Côtiers (DYNECO), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Physiologie et biotechnologie des Algues (PBA), Biotechnologies et Ressources Marines (BRM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Mesodinium rubrum, Teleaulax amphioxeia, [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, ecophysiology, full factorial design, global change, Dinophysis, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, [SDV.EE.IEO]Life Sciences [q-bio]/Ecology, environment/Symbiosis
Abstract

International audience; The cryptophyte Teleaulax amphioxeia is a source of plastids for the ciliate Mesodinium rubrum and both organisms are members of the trophic chain of several species of Dinophysis. It is important to better understand the ecology of organisms at the first trophic levels before assessing the impact of principal factors of global change on Dinophysis spp.. Therefore, combined effects of temperature, irradiance and pH on growth rate, photosynthetic activity and pigment content of a temperate strain of T. amphioxeia were studied using a full factorial design (central composite design 23*) in 17 individually controlled bioreactors. The derived model predicted an optimal growth rate of T. amphioxeia at a light intensity of 400 µmol photons · m-2 · s-1, more acidic pH (7.6) than the current average and a temperature of 17.6 °C. An interaction between temperature and irradiance on growth was also found, while pH did not have any significant effect. Subsequently, to investigate potential impacts of prey quality and quantity on the physiology of the predator, M. rubrum was fed two separate prey: predator ratios with cultures of T. amphioxeia previously acclimated at two different light intensities (100 and 400 µmol photons · m-2 · s-1). M. rubrum growth appeared to be significantly dependant on prey quantity while effect of prey quality was not observed. This multi-parametric study indicated a high potential for a significant increase of T. amphioxeia in future climate conditions but to what extent this would lead to increased occurrences of Mesodinium spp. and Dinophysis spp. should be further investigated.

Published
2020
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9. Copepod Grazing Influences Diatom Aggregation and Particle Dynamics

Author

Toullec, Jordan, Vincent, Dorothee, Frohn, Laura, Miner, Philippe, Le Goff, Manon, Devesa, Jeremy, Moriceau, Brivaëla, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord]), Agence Française pour la Biodiversité (AFB), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), ANR-16-CE01-0002,BioPSis,La pompe biologique de carbone: 2 silicifiés essentiels(2016), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, diatom aggregate, ACL, zooplankton fecal pellets, copepod, marine snow, sinking velocity, sinking rates, euterpina-acutifrons, Rolling tank, grazing experiment, diel vertical migration, fluorescence analysis, particle dynamics, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, feeding-behavior, organic-matter, calanus-helgolandicus, transparent exopolymeric particles
Abstract

WOS:000502962100001; International audience; In marine ecosystems, carbon export is driven by particle flux which is modulated by aggregation, remineralization, and grazing processes. Zooplankton contribute to the sinking flux through the egestion of fast sinking fecal pellets but may also attenuate the flux by tearing apart phytoplankton aggregates into small pieces through swimming activity or direct ingestion. Freely suspended cells, artificial monospecific aggregates from two different diatom species (Chaetoceros neogracile and Skeletonema merinol) and natural aggregates of Melosira sp. were independently incubated with five different copepod species (Acadia clausi, Temora longicomis, Calanus helgolandicus, Euterpina acutifrons, and Calanus hyperboreus). During the grazing experiments initiated with free diatoms, E. acutifrons feeding activity evidenced by ingestion rates of 157 +/- 155 ng Chl a ind(-1) d(-1), induced a significant increase of S. marinoi aggregation. Transparent exopolymeric particles (TEP) production was only slightly boosted by the presence of grazers and turbulences created by swimming may be the main trigger of the aggregation processes. All copepods studied were able to graze on aggregates and quantitative estimates led to chlorophyll a ingestion rates (expressed in Chla a equivalent, i.e., the sum of chlorophyll a and pheopigments in their guts) ranging from 4 to 23 ng Chl a(eq) ind(-1) d(-1). The relation between equivalent spherical diameters (ESDs) and sinking velocities of the aggregates did not significantly change after grazing, suggesting that copepod grazing did not affect aggregate density as also shown by Si:C and C:N ratios. Three main trends in particle dynamics could be identified and further linked to the copepod feeding behavior and the size ratio between prey and predators: (1) Fragmentation of S. marinoi aggregates by the cruise feeder T. longicomis and of Melosira sp. aggregates by C. hyperboreus at prey to predator size ratios larger than 15; (2) no change of particle dynamics in the presence of the detritic cruise feeder E acutifrons; and finally (3) re-aggregation of C. neogracile and S. marinoi aggregates when the two filter feeders A. clausi and C. helgolandicus were grazing on aggregate at prey to predator size ratios lower than 10. Aggregation of freely suspended cells or small aggregates was facilitated by turbulence resulting from active swimming of small copepods. However, stronger turbulence created by larger cruise feeders copepods prevent aggregate formation and even made them vulnerable to breakage.

Published
2019
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10. Variable Crustal Production Originating From Mantle Source Heterogeneity Beneath the South East Indian Ridge and Amsterdam‐St. Paul Plateau

Author

Marcia Maia, Eric Mittelstaedt, A.L.R. Sibrant, David W. Graham, Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Idaho], University of Idaho [Moscow, USA], Department of Civil Environmental and Architectural Engineering, University of Kansas [Lawrence] (KU), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Idaho State University, Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, 010504 meteorology & atmospheric sciences, Paul Plateau, ywords, 010502 geochemistry & geophysics, South East Indian Ridge, 01 natural sciences, Mantle (geology), Paleontology, Geophysics, oceanic plateaus, plume-ridge interaction, 13. Climate action, Geochemistry and Petrology, [SDU]Sciences of the Universe [physics], South east, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Amsterdam-St, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, geophysical and geochemical evidence, Geology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences
Abstract

International audience; The Amsterdam-St. Paul (ASP) Plateau formed by interaction between the South East Indian Ridge (SEIR) and the ASP mantle plume during the last 10 Myr. The combined bathymetry and gravity-derived crustal thickness anomalies along the present and paleoaxes of the SEIR atop the plateau indicate: (1) a thicker crust and shallower water depth along the southern part of segment I2 during much of the last 10 Myr; (2) an earlier decrease (~1.4 Ma) in crustal thickness along the southern part of I2 compared to the northern part (~0.9 Ma) during the most recent period of reduced magmatism; (3) a topographic transition at ~0.7 Ma and during the last 0.1 Myr; and (4) an approximately uniform crustal thickness (8 km) along the entire I2 segment today. These observations require spatial and temporal variations in magma production during construction of the ASP Plateau over the last 3 Myr. We propose that during periods of weaker plume magma flux, spatial variations in upper mantle temperature and composition are small, and lead to small variations in crustal thickness along-axis. In contrast, during periods of stronger plume magma flux, spatial contrasts in upper mantle temperature and composition (fertility) are large, leading to significant variations in crustal thickness. Along-axis variations of 3 He/ 4 He, Δ8/4Pb, K/Ti, and Na 8 in "zero-age" basalts indicate that there is a gradient in the underlying mantle material, from a "common" mantle plume component (Δ8/4Pb~60) stronger in the north to a DUPAL component (Δ8/4Pb~110) dominating in the south. keywords: oceanic plateaus, plume-ridge interaction, Amsterdam St. Paul Plateau, South East Indian Ridge, geophysical and geochemical evidence key points:-Crustal architecture of the Amsterdam St. Paul Plateau records high and low plume flux stages during mantle plume-spreading ridge interaction-Plume magma flux decreased earlier in the south than in the north along a single spreading segment.-Along-axis differences in crustal thickness and Pb and He isotopes suggest both shallow mantle and plume heterogeneities.

Published
2019
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11. Large impact of Stokes drift on the fate of surface floating debris in the South Indian Basin

Author

Bruno Blanke, Thierry Huck, Fabrice Ardhuin, Delphine Dobler, Elodie Martinez, Nicolas Grima, Christophe Maes, Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Division Hydrographie Océanographie et Météorologie Militaire (HOM), Service hydrographique et océanographique de la Marine, 17-EURE-0015 - ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, Entrainment (hydrodynamics), Microplastics, Marine debris, India, 010501 environmental sciences, Aquatic Science, Oceanography, 01 natural sciences, Stokes drift, Physics::Geophysics, Physics::Fluid Dynamics, symbols.namesake, Lagrangian analysis, Seawater, Water Pollutants, 14. Life underwater, Indian Ocean, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Ocean surface pathways, Pacific Ocean, Turbulent diffusion, Advection, 010604 marine biology & hydrobiology, Ocean current, Accumulation zone, Pollution, 13. Climate action, symbols, Plastics, Geology, Environmental Monitoring
Abstract

International audience; In the open ocean, floating surface debris such as plastics concentrate in five main accumulation zones centered around 30 • latitude, far from highly turbulent areas. Using Lagrangian advection of numerical particles by surface currents from ocean model reanalysis, previous studies have shown long-distance connection from the accumulation zones of the South Indian to the South Pacific oceans. An important physical process affecting surface particles but missing in such analyses is wave-induced Stokes drift. Taking into account surface Stokes drift from a wave model reanalysis radically changes the fate of South Indian particles. The convergence region moves from the east to the west of the basin, so particles leak to the South Atlantic rather than the South Pacific. Stokes drift changes the South Indian sensitive balance between Ekman convergence and turbulent diffusion processes, inducing either westward entrainment in the north of the accumulation zone, or eastward entrainment in the south.

Published
2019
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12. Earthquake crisis unveils the growth of an incipient continental fault system

Author

Eulàlia Gràcia, Yann Klinger, Ingo Grevemeyer, Rafael Bartolomé, Héctor Perea, Claudio Lo Iacono, Alcinoe Calahorrano, S. Diez, Laura Gómez de la Peña, Miquel Camafort, Antonio Villaseñor, César R. Ranero, Sara Martínez-Loriente, Alain Rabaute, Sergio Costa, Elia d'Acremont, Institute of Marine Sciences / Institut de Ciències del Mar [Barcelona] (ICM), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), GEOMAR - Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Scripps Institution of Oceanography (SIO), University of California [San Diego] (UC San Diego), University of California-University of California, University College Dublin [Dublin] (UCD), Institute of Earth Sciences Jaume Almera, Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), University of Southampton, Unitat de Tecnologia Marina, Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institució Catalana de Recerca i Estudis Avançats (ICREA), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Ministerio de Economía y Competitividad (España), European Commission, Villaseñor, Antonio [0000-0001-8592-4832], Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), and Villaseñor, Antonio

Subjects
Africa-Iberia plate, 0301 basic medicine, General Physics and Astronomy, 02 engineering and technology, Fault (geology), Displacement (vector), Large earthquakes, Bathymetry, lcsh:Science, Seismology, geography.geographical_feature_category, Multidisciplinary, Inversion, Geology, 021001 nanoscience & nanotechnology, Alboran Sea, Geophysics, seismic-hazard, San-Andreas fault, 0210 nano-technology, Earthquake, Evolution, Science, Inversion (geology), slip-rate, Volcanology, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], General Biochemistry, Genetics and Molecular Biology, Article, 03 medical and health sciences, 14. Life underwater, Al-Hoceima earthquake, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, Tectonics, deformation, Natural hazards, General Chemistry, Plate tectonics, 030104 developmental biology, Seismic hazard, 13. Climate action, Constraints, Reflection (physics), lcsh:Q, Submarine pipeline
Abstract

This article have a datasets associated "Regional centroid moment tensors for earthquakes in the 2016 South Alboran seismic crisis" http://hdl.handle.net/10261/177887, Large continental faults extend for thousands of kilometres to form boundaries between rigid tectonic blocks. These faults are associated with prominent topographic features and can produce large earthquakes. Here we show the first evidence of a major tectonic structure in its initial-stage, the Al-Idrissi Fault System (AIFS), in the Alboran Sea. Combining bathymetric and seismic reflection data, together with seismological analyses of the 2016 M-w 6.4 earthquake offshore Morocco - the largest event ever recorded in the area - we unveil a 3D geometry for the AIFS. We report evidence of left-lateral strike-slip displacement, characterise the fault segmentation and demonstrate that AIFS is the source of the 2016 events. The occurrence of the M-w 6.4 earthquake together with historical and instrumental events supports that the AIFS is currently growing through propagation and linkage of its segments. Thus, the AIFS provides a unique model of the inception and growth of a young plate boundary fault system., This research was supported by projects CGL2011-30005-C02-02, CTM2015-70155-R and Acción IDRISSI (MINECO/FEDER), shiptime on board the R/V Sarmiento de Gamboa and R/V Angeles Alvariño, EuroFleets-2 grant agreement 312762, and access to IFREMER AUVs AsterX and IdefX (France) through Ocean Facilities Exchange Group (OFEG). We also thank the Instituto Geografico Nacional (IGN, Spain) for providing seismological data. H.P. acknowledges the EU Horizon 2020 programme under grant agreement No H2020-MSCA-IF-2014 657769. E.d’A. acknowledges the French programme Actions Marges, the LabexMER (ANR-10-LABX-19-01) and the EuroFleets grant agreement 228344.

Published
2019
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13. The Sea of Marmara during Marine Isotope Stages 5 and 6

Author

Nurettin Yakupoğlu, Mehmet Sakınç, Julia Kende, Cerennaz Bozyiğit, Pierre Henry, Gülsen Uçarkuş, Ozlem Makaroglu, Burak Yalamaz, Suzanne A.G. Leroy, Kürşad Kadir Eriş, M. Namık Çağatay, Istanbul Technical University, Istanbul University, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Avrasya Yerbilimleri Enstitüsü, Istanbul Teknik Universitesi, Istanbul Technical University (ITÜ), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Institute for the Environment [Uxbridge], Brunel University London [Uxbridge], ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), and Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010506 paleontology, Archeology, Sea of Marmara, 010504 meteorology & atmospheric sciences, Lithology, [SDE.MCG]Environmental Sciences/Global Changes, Sedimentology-marine cores, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Marine isotope stages 5-6, Eastern Europe, Structural basin, 01 natural sciences, Isotopes of oxygen, Paleoceanography, Sill, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, 14. Life underwater, Glacial period, Stadial, Sapropels, Ecology, Evolution, Behavior and Systematics, Sea level, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Global and Planetary Change, geography, geography.geographical_feature_category, Geology, Late Quaternary, Marine Isotope stages 5-6, Geochemical proxies, Oceanography, 13. Climate action, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, [SDE]Environmental Sciences, Late quaternary
Abstract

International audience; Multi-proxy analyses and lithology of two cores, MRS-CS18 and MRS-CS27, from the İmralı Basin of the Sea of Marmara (SoM) provide important new information on environmental conditions, relative sea level, and sill depths of the straits of Bosporus and Dardanelles during the marine isotope stages (MIS) 5 and 6. The fossil and multi-proxy geochemical records show that lacustrine conditions prevailed in the SoM during most of MIS-6, from 173 to 134 ka BP, and that the transition to marine conditions during Termination II took place at~134.06±1.10 ka BP. MIS5 interstadials a, c, and e witnessed the formation of three sapropels (MSAP-4, MSAP-3 and MSAP-2) under suboxic to anoxic marine conditions, whereas during stadials MIS5b (~94-86) and MIS5d (~112-105 ka BP), lacustrine and marine conditions with deposition of sediments having relatively low TOC contents (

Published
2019
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14. Quantifying Biogenic Versus Detrital Carbonates on Marine Shelf: An Isotopic Approach

Author

V. Pasquier, S. Revillon, E. Leroux, S. Molliex, L. Mocochain, M. Rabineau, Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Service de Physique Théorique (SPhT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Bretagne Sud (UBS), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), and Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Geochemistry, glacial - interglacial, 010502 geochemistry & geophysics, 01 natural sciences, source-to-sink, 87Sr/86Srcarbonate, chemistry.chemical_compound, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 14. Life underwater, Glacial period, lcsh:Science, Sedimentary budget, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, strontium isotope stratigraphy, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Terrigenous sediment, Sr-87/Sr-86(carbonate), Sediment, glacial – interglacial, 87 Sr/ 86 Sr carbonate, chemistry, 13. Climate action, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Interglacial, glacial -interglacial, General Earth and Planetary Sciences, Carbonate, lcsh:Q, Siliciclastic, Sedimentary rock, detrital carbonate export, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Geology
Abstract

International audience; The terrigenous sedimentary budget of passive margins, records variations in past sedimentary fluxes, and thus can be used to infer past variations of Earth surface deformation processes or climate change. Accurate estimates of sediment fluxes over various times and spatial scales are therefore crucial. Traditionally, offshore sediment volume determination only considers siliciclastic accumulation, the carbonate fraction (i.e., CaCO 3) being considered only as in situ production. Here we propose a new geochemical methodology to decipher and quantify the number of detrital carbonates in comparison to in situ produced biogenic carbonates. This isotopic approach enables considering the export of detrital carbonates and investigating its effect on sediment budgets. This study, located in the Gulf of Lion, is based on a 300 m long sediment borehole located near the shelf break and covering the last 500 000 years (i.e., five glacial-interglacial periods). Strontium isotope (87 Sr/ 86 Sr) of carbonate fractions (0.70809 to 0.70858) are significantly less radiogenic than modern seawater (i.e., 0.7092) and show fluctuations in agreement with stratigraphic and climatic variations. These results suggest an unsuspected high export of detrital carbonates from the catchment area during both glacial (between 55 and 85% of the sedimentary carbonate fraction) and interglacial (between 30 and 50%) conditions. Thus, not only do detrital carbonate fluxes need to be factored into sediment flux calculations, but these results also suggest that detrital carbonate components could potentially have a strong influence on bulk carbonate 87 Sr/ 86 Sr ratios when not obtained from micro drilled biogenic carbonates, such as the entirety of the Precambrian Sr chemostratigraphic record.

Published
2019
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15. Diachronic UAV Photogrammetry of a Sandy Beach in Brittany (France) for a Long-Term Coastal Observatory

Author

Marion Jaud, Christophe Delacourt, Nicolas Le Dantec, Pascal Allemand, Jérôme Ammann, Philippe Grandjean, Henri Nouaille, Christophe Prunier, Véronique Cuq, Emmanuel Augereau, Lucie Cocquempot, France Floc’h, Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Géosciences Océan (LGO), Université de Brest (UBO)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement - Direction Eau Mer et Fleuves (Cerema Direction Eau Mer et Fleuves), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Littoral, Environnement, Télédétection, Géomatique (LETG - Brest), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), Observatoire des Sciences de l'Univers de La Réunion (OSU-Réunion), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École Pratique des Hautes Études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN)

Subjects
010504 meteorology & atmospheric sciences, UAV, Geography, Planning and Development, 0211 other engineering and technologies, lcsh:G1-922, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Context (language use), 02 engineering and technology, 01 natural sciences, Observatory, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, Computers in Earth Sciences, Digital elevation model, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Remote sensing, Coastal hazards, Storm, SfM photogrammetry, Drone, Photogrammetry, 13. Climate action, coastal observatory, beach monitoring, Environmental science, Multirotor, lcsh:Geography (General)
Abstract

International audience; In the dual context of coastal hazard intensification and the growing number of stakes exposed to these hazards, coastal observatories are in demand to provide a structured framework dedicated to long-term monitoring. This article describes the drone-based photogrammetry monitoring performed since 2006 on Porsmilin Beach (Brittany, France) in the framework of the DYNALIT (Littoral and Coastline Dynamics) observatory, focusing on data quality and the consistency of long-term time series under the influence of multiple technological evolutions: Unmanned Aerial Vehicles (UAV) platforms with the arrival of electric multirotor drones, processing tools with the development of structure-from-motion (SfM) photogrammetry, and operational modes of survey. A study case is presented to show the potential of UAV monitoring to study storm impacts and beach resilience. The relevance of high-accuracy monitoring is also highlighted. With the current method, an accuracy of 3 cm can be achieved on the digital elevation model (DEM) and the orthophotograph. The question of the representativity and frequency of DEM time points is raised.

Published
2019
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16. Structural controls on polyphase hydrothermal dolomitization in the Kinta Valley, Malaysia: Paragenesis and regional tectono-magmatism

Author

Ramasamy Nagarajan, Manoj Joseph Mathew, H. Tim Breitfeld, Benjamin Sautter, Poon Xin Hui, Mu. Ramkumar, Michael Poppelreiter, Numair Ahmed Siddiqui, M. Santosh, David Menier, South-East Asia Carbonate Research Laboratory (SEACARL), Universiti Teknologi, Periyar University, Universiti Teknologi PETRONAS (UTP), Université de Bretagne Sud (UBS), Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Asian Environmental Research Group, National Institute for Environmental Studies (NIES), Faculty of Science - Japan, Laboratoire Géosciences Océan (LGO), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Metamorphic rock, Geochemistry, Hydrothermal dolomite, Fault (geology), 010502 geochemistry & geophysics, 01 natural sciences, Structural evolution, Paragenesis, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, Rock microstructure, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Tectonics, Magmatism, Malaysia, Geology, Facies, Dolomitization, Structural geology
Abstract

In the eastern side of the Malay Peninsula, thick successions of limestone formations preserve important records of the Mesozoic and Cenozoic tectonic events. Here we investigate the strata- and fracture-bound hydrothermal dolomites in the Palaeozoic carbonates of the Kinta Valley, western Peninsular Malaysia. Based on their textural and morphologic characteristics, structural relationships with the host rock, different facies types, and associations with hydrothermal calcite and low-grade metamorphic marble, we attempt to trace their polyphase origin and relationship with thermo-tectonic events of the region. A detailed evaluation of the nature of brecciation and crystallization of polyphase dolomites, dolomitic limestones, limestones and marble, under the influences of episodic faulting, is associated with the regional structural geology with emphasis on pre-existing fault reactivations, granitic emplacement and progressive thermal influence. Supply of Mg2+ from the host rock for dolomitization, limited and episodic influx of circulating fluids and cessation of thermo-tectonic evolution with progressive cooling are also inferred. Correlating the geological events in western Peninsular Malaysia with regional structural dynamics reveals that the major deformation episodes exerted first order controls on the loci of dolomite occurrences. The occurrence, geometry and structural relationships of the dolomites were controlled by successive magmatic events, whereas, the intensity of replacement dolomitization was controlled by host rock texture and varied bulk chemistry, together with the nature of circulating fluids.

Published
2019
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17. Insight into the measurement of dissolved 227Ac in seawater using radium delayed coincidence counter

Author

Paul B. Henderson, Virginie Sanial, François Lacan, Marc Souhaut, Pieter van Beek, Matthew A. Charette, Emilie Le Roy, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), GEOMAR LEGOS, Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Department of Marine Chemistry and Geochemistry (WHOI), Woods Hole Oceanographic Institution (WHOI), Division of Marine Science [Mississippi], University of Southern Mississippi (USM), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3)

Subjects
0106 biological sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Radionuclide, Reproducibility, Materials science, 010504 meteorology & atmospheric sciences, 010604 marine biology & hydrobiology, Extraction (chemistry), Analytical chemistry, chemistry.chemical_element, General Chemistry, Repeatability, Secular equilibrium, Oceanography, 01 natural sciences, Radium, chemistry, 13. Climate action, Environmental Chemistry, Seawater, Nuclide, 0105 earth and related environmental sciences, Water Science and Technology
Abstract

International audience; Due to the low abundance of 227 Ac in seawater, the analysis of this radionuclide requires the use of high-sensitivity, low-background instruments and the collection of large volume samples. A promising technique relies on the pre-concentration of 227 Ac in seawater using cartridges impregnated with manganese oxide (Mn-cartridges) that are mounted on in situ pumps, and its measurement on a Radium Delayed Coincidence Counter (RaDeCC), usually used to analyze short-lived radium isotopes. In this work, we present an evaluation of this technique, including 1) the study of the performance of the RaDeCC measurements for 227 Ac fixed on Mn-cartridges (backgrounds, detector efficiency, repeatability), and 2) the determination of the efficiency of seawater 227 Ac extraction of the Mn-cartridges and its reproducibility for the first time, by using Mn-cartridges placed in series. Overall, we found a Mn-cartridge extraction efficiency of 47 ± 12% (1 SD). Repeatability experiments allowed us to estimate the uncertainties of the entire measurement of 19% (1 SD). Finally, in the aim to validate the method, the 227 Ac activities thus obtained are compared 1) to the 227 Ac activities determined in several samples using Mn-fibers (assuming 100% yield of 227 Ac extraction) and 2) to the 231 Pa activities determined at the same stations during the GEOVIDE cruise (GEOTRACES GA01), 231 Pa being the parent nuclide of 227 Ac (Deng et al., 2018). Only few studies 227 Ac and 231 Pa have been published so far due to the difficulty to analyze these two nuclides. First, the 227 Ac activities determined using Mn-cartridges agree well with the 227 Ac activities determined using Mn-fibers. Second, at depths where 227 Ac is usually found to be in secular equilibrium with 231 Pa (0-2000 m), we found good agreement between 227 Ac and 231 Pa, which validates the method used to determine 227 Ac activities, including the estimate of the Mn-cartridge extraction efficiency.

Published
2019
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18. SKIM, a Candidate Satellite Mission Exploring Global Ocean Currents and Waves

Author

Ardhuin, Fabrice, Brandt, Peter, Gaultier, Lucile, Donlon, Craig, Battaglia, Alessandro, Boy, Francois, Casal, Tania, Chapron, Bertrand, Collard, Fabrice, Cravatte, Sophie, Delouis, Jean-Marc, De Witte, Erik, Dibarboure, Gerald, Engen, Geir, Johnsen, Harald, Lique, Camille, Lopez-Dekker, Paco, Maes, Christophe, Martin, Adrien, Marie, Louis, Menemenlis, Dimitris, Nouguier, Frederic, Peureux, Charles, Rampal, Pierre, Ressler, Gerhard, Rio, Marie-Helene, Rommen, Bjorn, Shutler, Jamie D., Suess, Martin, Tsamados, Michel, Ubelmann, Clement, van Sebille, Erik, van den Oever, Martin, Stammer, Detlef, Sub Physical Oceanography, Marine and Atmospheric Research, Sub Physical Oceanography, Marine and Atmospheric Research, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), OceanDataLab, European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA), Centre National d'Études Spatiales [Toulouse] (CNES), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institut de Recherche pour le Développement (IRD), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), National Oceanography Centre [Southampton] (NOC), University of Southampton, Centre for Polar Observation & Modelling, University College of London [London] (UCL), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Grantham Institute for Climate Change and the Environment, Imperial College London, ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), ODL - OceanDataLab, European Space Agency (ESA), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, lcsh:QH1-199.5, 010504 meteorology & atmospheric sciences, BUDGET, Oceanography, 01 natural sciences, 7. Clean energy, remote sensing, Arctic, ocean waves, altimetry, Wind wave, SPACE, WATER, Marine & Freshwater Biology, lcsh:Science, Delta-k interferometry, Physics::Atmospheric and Oceanic Physics, Water Science and Technology, Global and Planetary Change, Doppler centroid, IN-SITU, ocean current, Doppler, SEA-SURFACE KINEMATICS, Life Sciences & Biomedicine, Meteorology, CIRCULATION, Ocean Engineering, VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Oseanografi: 452, Environmental Sciences & Ecology, Sea state, lcsh:General. Including nature conservation, geographical distribution, Aquatic Science, tropics, Altimetry, Ocean current, Radar, Remote sensing, VDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452, 14. Life underwater, Altimeter, Rogue wave, Sea ice concentration, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Science & Technology, 010604 marine biology & hydrobiology, Scatterometer, VELOCITY, TRANSPORT, Boundary current, MODEL, 13. Climate action, MIXED-LAYER HEAT, Environmental science, lcsh:Q, sea state, Environmental Sciences
Abstract

The Sea surface KInematics Multiscale monitoring (SKIM) satellite mission is designed to explore ocean surface current and waves. This includes tropical currents, notably the poorly known patterns of divergence and their impact on the ocean heat budget, and monitoring of the emerging Arctic up to 82.5°N. SKIM will also make unprecedented direct measurements of strong currents, from boundary currents to the Antarctic circumpolar current, and their interaction with ocean waves with expected impacts on air-sea fluxes and extreme waves. For the first time, SKIM will directly measure the ocean surface current vector from space. The main instrument on SKIM is a Ka-band conically scanning, multi-beam Doppler radar altimeter/wave scatterometer that includes a state-of-the-art nadir beam comparable to the Poseidon-4 instrument on Sentinel 6. The well proven Doppler pulse-pair technique will give a surface drift velocity representative of the top meter of the ocean, after subtracting a large wave-induced contribution. Horizontal velocity components will be obtained with an accuracy better than 7 cm/s for horizontal wavelengths larger than 80 km and time resolutions larger than 15 days, with a mean revisit time of 4 days for of 99% of the global oceans. This will provide unique and innovative measurements that will further our understanding of the transports in the upper ocean layer, permanently distributing heat, carbon, plankton, and plastics. SKIM will also benefit from co-located measurements of water vapor, rain rate, sea ice concentration, and wind vectors provided by the European operational satellite MetOp-SG(B), allowing many joint analyses. SKIM is one of the two candidate satellite missions under development for ESA Earth Explorer 9. The other candidate is the Far infrared Radiation Understanding and Monitoring (FORUM). The final selection will be announced by September 2019, for a launch in the coming decade. Copyright © 2019 Ardhuin, Brandt, Gaultier, Donlon, Battaglia, Boy, Casal, Chapron, Collard, Cravatte, Delouis, De Witte, Dibarboure, Engen, Johnsen, Lique, Lopez-Dekker, Maes, Martin, Marié, Menemenlis, Nouguier, Peureux, Rampal, Ressler, Rio, Rommen, Shutler, Suess, Tsamados, Ubelmann, van Sebille, van den Oever and Stammer. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).

Published
2019
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19. Sea State Trends and Variability: Consistency Between Models, Altimeters, Buoys, and Seismic Data (1979-2016)

Author

Thomas Lecocq, Eléonore Stutzmann, Fabrice Ardhuin, Justin E. Stopa, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, long-term trends, Sea state, Seismic noise, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Physics::Geophysics, data homogeneity, Geochemistry and Petrology, Wave height, Earth and Planetary Sciences (miscellaneous), Hindcast, 14. Life underwater, Altimeter, Physics::Atmospheric and Oceanic Physics, COWCLIP, 0105 earth and related environmental sciences, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Microseism, Buoy, wave hindcasting, Climate Forecast System Reanalysis, Geophysics, 13. Climate action, Space and Planetary Science, Climatology, Climate Forecast System, seismic noise, Geology
Abstract

International audience; Wave hindcasts of long time series (>30 years) have been instrumental in understanding the wave climate. However, it is still difficult to have a consistent reanalysis suitable for study of trends and interannual variability. Here we explore the consistency of a wave hindcast with independent observations from moored buoys, satellite altimeters, and seismic data. We use the Climate Forecast System Reanalysis (CFSR) winds to drive a wave model since extreme events are generally well captured. Unfortunately, the original CFSR winds are not homogeneous in time. We systematically modify this wind field in time and space to produce a wave field that has homogeneous differences against the Globwave/SeaStateCCI altimeter wave height database. These corrections to the winds and resulting waves are validated using independent buoy and microseism data. We particularly use seismic data in the dominant double-frequency band, around 5-s period, that are generated by opposing waves of equal frequencies. The seismic data confirms that our correction of time-varying biases is consistent, even in remote and undersampled region such as the Southern Ocean where the original CFSR biases are strongest. Our analysis is performed on monthly time series, and we expect the monthly statistics to be better suited for climate studies. Remaining issues with time consistency of reanalysis products and associated wave hindcasts are further discussed.

Published
2019
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20. Palaeoenvironmental reconstructions during the Meso- to Neolithic transition (9.2–5.3 cal. ka BP) in Northwestern France: Palynological evidences

Author

Muriel Vidal, Pierre Stéphan, Axel Ehrhold, Pascal Roy, Clément Lambert, Yvan Pailler, Evelyne Goubert, Aurélie Penaud, Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national de recherches archéologiques préventives, centre archéologique de Cesson-Sévigné (Inrap, Cesson-Sévigné), Institut national de recherches archéologiques préventives (Inrap), Trajectoires - UMR 8215, Université Paris 1 Panthéon-Sorbonne (UP1)-Centre National de la Recherche Scientifique (CNRS), Littoral, Environnement, Télédétection, Géomatique (LETG - Brest), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-Université de Nantes (UN)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Université de Brest (UBO)-Université de Bretagne Sud (UBS)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École pratique des hautes études (EPHE), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
climate variability, 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, [SDE.MCG]Environmental Sciences/Global Changes, benthic foraminifera, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 01 natural sciences, [SHS]Humanities and Social Sciences, Paleontology, Mesolithic, Holocene, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Earth-Surface Processes, Palynology, human impacts, Global and Planetary Change, Ecology, pollen grains, palaeoenvironments reconstructions, 13. Climate action, [SDU]Sciences of the Universe [physics], [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, [SDE]Environmental Sciences, dinoflagellate cysts, Bay, Geology
Abstract

Sedimentological, palynological, and micropalaeontological studies carried out throughout the first half of the Holocene, during the Mesolithic/Neolithic transition in the Bay of Brest (i.e. 9200–9000 and 6600–5300 cal. BP) and in the Bay of Douarnenez (i.e. 9200–8400 cal. BP), allowed characterizing coastal environmental changes under the increasing influence of the relative sea-level rise. The gradual flooding of the two studied sites implied a transition from river valleys to oceanic bays as revealed by the gradual retreat of salt marsh environments, as detected through palynological analysis. In addition, these high-resolution studies highlight the regional imprint of the North Atlantic millennial climate variability in north-western coastal environments. Two cold climate events are indeed suggested to have been locally marked by a moisture increase, mainly detected by increases in Lingulodinium machaerophorum, Corylus, and Alnus percentages at 8550 cal. BP in the Bay of Douarnenez and at 6250 cal. BP in the Bay of Brest. Moreover, regarding the Neolithic transition timing in the Bay of Douarnenez, large pollen grains of Poaceae (i.e. Cerealia-type pollen grains) have been detected at around 8600 cal. BP, that is, 1500 years before the general accepted cereal cropping appearance in Western France. These results, consistent with other palynological studies conducted in the French Atlantic coast, could underline a Mesolithic ‘proto-agriculture’ in Brittany.

Published
2019
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21. Cultures of Dinophysis sacculus, D. acuminata and pectenotoxin 2 affect gametes and fertilization success of the Pacific oyster, Crassostrea gigas

Author

Manoella Sibat, Caroline Fabioux, Philipp Hess, Sylvain Gaillard, Véronique Séchet, Damien Réveillon, Lucas Zaccagnini, Florent Malo, Liliane Carpentier, Nelly Le Goïc, Hélène Hégaret, Myrina Boulais, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Male, Okadaic acid, 010504 meteorology & atmospheric sciences, Health, Toxicology and Mutagenesis, media_common.quotation_subject, Zoology, 010501 environmental sciences, Toxicology, 01 natural sciences, Algal bloom, medicine, Animals, Humans, 14. Life underwater, Crassostrea, Furans, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Shellfish, Pyrans, 0105 earth and related environmental sciences, media_common, biology, Fertilization success, Dinoflagellate, General Medicine, Pacific oyster, biology.organism_classification, Pollution, [SDV.BA.ZI]Life Sciences [q-bio]/Animal biology/Invertebrate Zoology, Pectenotoxins, Germ Cells, medicine.anatomical_structure, Dinoflagellida, Gamete, Marine Toxins, [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology, France, Macrolides, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Dinophysis spp, Reproduction, Oyster gametes, Dinophysis
Abstract

International audience; Harmful algal blooms (HABs) of toxic species of the dinoflagellate genus Dinophysis are a threat to human health as they are mainly responsible for diarrheic shellfish poisoning (DSP) in the consumers of contaminated shellfish. Such contamination leads to shellfish farm closures causing major economic and social issues. The direct effects of numerous HAB species have been demonstrated on adult bivalves, whereas the effects on critical early life stages remain relatively unexplored. The present study aimed to determine the in vitro effects of either cultivated strains of D. sacculus and D. acuminata isolated from France or their associated toxins (i.e. okadaic acid (OA) and pectenotoxin 2 (PTX2)) on the quality of the gametes of the Pacific oyster Crassostrea gigas. This was performed by assessing the ROS production and viability of the gametes using flow cytometry, and fertilization success using microscopic counts. Oocytes were more affected than spermatozoa and their mortality and ROS production increased in the presence of D. sacculus and PTX2, respectively. A decrease in fertilization success was observed at concentrations as low as 0.5 cell mL-1 of Dinophysis spp. and 5 nM of PTX2, whereas no effect of OA could be observed. The effect on fertilization success was higher when both gamete types were concomitantly exposed compared to separate exposures, suggesting a synergistic effect. Our results also suggest that the effects could be due to cell-to-cell contact. These results highlight a potential effect of Dinophysis spp. and PTX2 on reproduction and recruitment of the Pacific oyster.

Published
2020
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22. Organic matter isotopes reveal enhanced rainfall activity in Northwestern Mediterranean borderland during warm substages of the last 200 kyr

Author

Marina Rabineau, Zohra Mokeddem, Pierre Sansjofre, Sidonie Révillon, Samuel Toucanne, Yama Dixit, Virgil Pasquier, Laboratoire Géosciences Océan (LGO), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Nanyang Technological University [Singapour], ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Earth Observatory of Singapore

Subjects
Mediterranean climate, Rainfall, 010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, North Mediterranean borderland, Sapropel, Geology [Science], Mediterranean, Monsoon, 01 natural sciences, Mediterranean Basin, Mediterranean sea, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Climate oscillation, Geology, 15. Life on land, Oceanography, 13. Climate action, Pluvial, North Atlantic oscillation, Organic matter
Abstract

International audience; In this study we use bulk sediment organic matter stable isotopes (δ13Corg and δ15N) to examine the nature and timing of preserved organic matter in borehole PRGL1-4 from Northwestern Mediterranean Sea. This region is known as a transitional zone between the North Atlantic atmospheric circulation and the North African monsoon system. In the Gulf of Lion (SE France), increased inputs of organic matter from sediment-laden rivers occurred during warm substages of the last 200 kyr (MIS 5e, 5c, and 5a; MIS 6d, and 6b). Increased terrestrial organic matter are inferred from organic carbon isotopic composition (δ13Corg), and are interpreted as resulting from enhanced rainfall over the Rhone river catchment area. Such increase in terrestrial organic carbon induced enhancement of the primary productivity leading to the formation of local oxygen minimum zone as demonstrated by ∼3‰ values in δ15N. Comparison with regional paleohydrological records from the northern Mediterranean borderlands reveals the regional character of these pluvial events. Taking advantage of the location of PRGL1-4 borehole, out of Mediterranean cyclogenesis area, we suggest that the pluvial events recorded during warm substages of the last 200 kyr occurred in response to enhanced passage of North Atlantic atmospheric perturbation over the Gulf of Lion catchment area (especially over Rhone river watershed which represent 80% of the GoL catchment area), a scenario possibly similar to that encountered today during negative- NAO like conditions. At a regional scale, our data suggests that high rainfall events over the Gulf of Lion catchement area and the Rhone watershed occurred at the time of North African summer monsoon and the sapropel deposition in the Mediterranean basin, thus highlighting a close coupling between mid- (North Atlantic) and low-latitudes (monsoon) climate systems. Importantly, our geochemical evidence from the Gulf of Lion support an extra-Mediterranean source for the regional pluvial events described in many paleoclimatic records from the northern Mediterrean borderlands during warm substages of the last climate cycles. Consequently, we suggest that this region as a whole could provide, in addition to the river runoff from the North African sector, the necessary conditions for the sapropel deposition.

Published
2019
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23. A comparison of bulk versus laser ablation trace element analyses in banded iron formations: Insights into the mechanisms leading to compositional variability

Author

Leslie J. Robbins, Martin Homann, Tyler J. Warchola, Marie Thoby, Stefan V. Lalonde, Kurt O. Konhauser, Ian S. Foster, Aleksandra M. Mloszewska, Daniel S. Alessi, University of Alberta, Laboratoire Géosciences Océan (LGO), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Distributed Systems Laboratory, University of Chicago, ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), and ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Laser ablation, 010504 meteorology & atmospheric sciences, Metamorphic rock, Trace element, Mineralogy, Geology, Hematite, 010502 geochemistry & geophysics, 01 natural sciences, Sedimentary depositional environment, Precambrian, 13. Climate action, Geochemistry and Petrology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, visual_art, visual_art.visual_art_medium, Banded iron formation, Seawater, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Banded iron formations (BIF) represent one of the few chemical sedimentary archives available for exploring the redox state of the Precambrian atmosphere-ocean system and the marine availability of biologically critical trace nutrients through time. Temporal records compiled for a number of trace elements show a relatively wide spread in concentrations spanning several orders of magnitude within a single deposit. It has been suggested that this spread is present in both bulk rock digestion and laser ablation data, however, the comparability of data from the two methods has not been thoroughly evaluated. Here, we provide a statistical assessment of how comparable laser ablation data of individual BIF hematite and magnetite grains are to one another, as well as how closely averages of laser ablation data approximate bulk rock values. To do so, we use (laser ablation)-high resolution inductively coupled plasma mass spectrometry ((LA)-HR-ICP-MS) data from 14 BIF slabs and corresponding powders that span four different formations. We focus in particular on BIF from the ≥3.75 Ga Nuvvuagittuq Supracrustal Belt (Quebec, Canada) and multiple BIF deposits of the 2.6–2.45 Ga Hamersley Group (North Western Australia), representing deposits separated by over a billion years and of differing metamorphic grade. The scaling between selected transition metals is also evaluated in light of expectations for possible delivery mechanisms of trace elements from seawater to BIF precursor sediments – the adsorption to hydrous ferric oxides, biological vectors, and detrital influence. Our findings show that average trace element concentrations between bulk versus laser ablation data typically vary within an order of magnitude. Furthermore, reproducibility between the two methods appears to be independent of formation age, metamorphic grade, or depositional setting. These findings underscore the overall fidelity of the BIF record at capturing seawater compositional signatures at various scales. We demonstrate that evaluations of ancient seawater chemistry using the BIF record are best served by a combined approach utilizing both bulk rock and laser ablation data, as bulk methods offer the most conservative proxy data for ancient seawater composition but may mask significant enrichments or depletions that are detectable at the grain-scale by laser ablation.

Published
2019
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24. Late Pleistocene evolution of the mixed siliciclastic and carbonate southwestern New Caledonia continental shelf/lagoon

Author

Charline Guerin, Guillaume Michel, Stephan J. Jorry, Valentin Gautier, Gwenael Jouet, Pascal Le Roy, Axel Ehrhold, SAUVADET, Margot, Interdisciplinary Graduate School for the Blue planet - - ISBlue2017 - ANR-17-EURE-0015 - EURE - VALID, Laboratoire Géosciences Océan (LGO), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Institut français de recherche pour l'exploitation de la mer (IFREMER), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), and ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)

Subjects
010506 paleontology, Incised valleys, [SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics, Escarpment, 010502 geochemistry & geophysics, Oceanography, [SDU.STU.OC] Sciences of the Universe [physics]/Earth Sciences/Oceanography, 01 natural sciences, Quaternary, Paleontology, chemistry.chemical_compound, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, Sea level, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Plateau, Terrigenous sediment, Continental shelf, chemistry, Clastic rock, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, Carbonate, Siliciclastic, [SDU.STU.PG] Sciences of the Universe [physics]/Earth Sciences/Paleontology, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Geology, Seismic stratigraphy
Abstract

The main island of New Caledonia (NC) is surrounded by the second largest barrier reef in the world after the Australian Great Barrier Reef. The Upper Pleistocene evolution of this barrier reef–lagoon complex offers the opportunity to examine the response of a modern mixed tropical siliciclastic/carbonate system to relative sea-level changes and to better constrain the relative role of lagoon backfilling and paleo-drainage system in sediment transfer across the shelf. This paper mainly focuses on the results of chronostratigraphic and sedimentological interpretations of new seismic, bathymetric and coring data collected in the SW NC lagoon. Several significant points are highlighted from this study and allow the construction of a refined model which includes the evolution of both the SW NC mixed shelf and lagoon. New results show that the NC lagoon has not recorded a reciprocal sedimentation during glacial-interglacial sea-level cycles but a unique mixed regime. Strong contrasts are observed and these depend above all on the two lagoon domains: the outer coral plateau and the inner lagoon depression corresponding to a semi-closed proximal basin which is separated from the plateau by a basement ridge. In the depression, clastic sediments remain dominant from early flooding to highstand stages while carbonate sedimentation continued through time across the coral plateau. This spatial contrast between terrigenous and carbonate deposits was maintained throughout various sea level cycles. Thus, even if spatial segregation is also observed for other examples of mixed shelf environments, the SW NC shelf appears quite unique in comparison to the other mixed systems when considering conceptual models of reciprocal sedimentation. Moreover, the presence of a semi-enclosed lagoon depression allows the preservation of larger volume of terrigenous deposits. This semi-filled geometry of the lagoon is assumed to be the result of several factors: a significant subsidence that offers accommodation for aggrading deposits, evacuation through channels of sediments mobilized during storm events, the tidal currents, and fairweather wave dynamics. Lastly, the inherited morphologic and structures may explain the geomorphic evolution of the “escarpment margin” type of the SW NC rimmed shelf and its differentiation with the opposite SE NC ramp type shelf.

Published
2019

25. A decision-making framework to reduce the risk of collisions between ships and whales

Author

Sèbe, Maxime, Christos, Kontovas, Linwood, Pendleton, Aménagement des Usages des Ressources et des Espaces marins et littoraux - Centre de droit et d'économie de la mer (AMURE), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDV.SA.AEP]Life Sciences [q-bio]/Agricultural sciences/Agriculture, economy and politics, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, [SDE.ES]Environmental Sciences/Environmental and Society
Abstract

International audience; Ship strikes are one of the main human-induced threats to whale survival. A variety of measures have been used or proposed to reduce collisions and subsequent mortality of whales. These include operational measures, such as mandatory speed reduction, or technical ones, such as detection tools. There is, however, a lack of a systematic approach to assessing the various measures that can mitigate the risk of ship collisions with whales. In this paper, a holistic approach is proposed to evaluate mitigation measures based on a risk assessment framework that has been adopted by the International Maritime Organization (IMO), namely the Formal Safety Assessment (FSA). Formal Safety Assessment (FSA) is "a rational and systematic process for assessing the risk related to maritime safety and the protection of the marine environment and for evaluating the costs and benefits of IMO's options for reducing these risks". The paper conceptualizes the use of a systematic risk assessment methodology, namely the FSA, to assess measures to reduce the risk of collisions between ships and whales.

Published
2019
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26. A Late Quaternary record of highstand shedding from an isolated carbonate platform (Juan de Nova, southern Indian Ocean)

Author

John W. Counts, Elda Miramontes, Natalia Vázquez Riveiros, Audrey Boissier, Sandrine Cheron, Jacques Giraudeau, Stephan J. Jorry, Gwenael Jouet, University College Dublin [Dublin] (UCD), Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), 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), UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR: 17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), 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 Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Géosciences Marines (GM), Environnements et Paléoenvironnements OCéaniques (EPOC), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Bretagne Sud (UBS)

Subjects
010504 meteorology & atmospheric sciences, Carbonate platform, Stratigraphy, atoll, Mozambique Channel, Environmental Science (miscellaneous), engineering.material, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Deep sea, aragonite, Sedimentary depositional environment, Paleontology, chemistry.chemical_compound, Aggradation, MIS 11, 14. Life underwater, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Aragonite, lcsh:QE1-996.5, Geology, sea‐level change, lcsh:Geology, sea-level change, chemistry, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, engineering, Carbonate, Quaternary, Juan de Nova Island
Abstract

International audience; A 27 m core collected on the sea floor near Juan de Nova island at 1,909 m depth in the SW Indian Ocean preserves a high-resolution record of carbonate sediment export to the deep sea over the past 1 Myr. Core chronology was established using calcareous nannofossil biostratigraphy and benthic foraminiferal δ 18 O. Throughout the core, preserved highstand intervals (MIS 1, 5, 7, 9, 11, 13, 15, 23 and 25) are marked by an increase in the aragonite content within the sediment. Aragonite is likely sourced from the nearby Juan de Nova carbonate platform ca 10 km to the south, and is interpreted as resulting from flooding of the platform top. Platform inundation allows carbonate muds to be winnowed from their original shallow-water environment of deposition, suspended in the water column, and redeposited onto the proximal slopes and within the basin. Sharp increases in aragonite content at the beginning of each highstand interval can be used to estimate the approximate sea-level range when platform flooding occurred; results show that the depth of the platform top has likely changed little over the past 1 Myr due to balanced aggradation and subsidence. Previously hypothesized large-scale aragonite dissolution cycles are evidenced by a disproportionally low aragonite increase during MIS 11. This study provides a new, exceptionally long record of highstand shedding, expanding the known occurrences of the process to the southern Indian Ocean and supporting its importance as a globally significant depositional mechanism that impacts deep-sea stratigraphic records. K E Y W O R D S aragonite, atoll, MIS 11, Mozambique Channel, sea-level change

Published
2019
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27. There is an inverse relationship between the capacity of climate change refugia and species adaptation potential

Author

Javid Kavousi, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), and ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, climate change refugia, Climate change, Biology, acclimation, global warming, 010603 evolutionary biology, 01 natural sciences, Marine species, Refugium (population biology), ocean acidification refugia, Environmental Chemistry, resilience, 0105 earth and related environmental sciences, General Environmental Science, Global and Planetary Change, Ecology, ACL, Global warming, refugial capacity, havens, marine species, refuges, acclimatization, 13. Climate action, Adaptation, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

This article is a commentary on Kapsensberg & Cyronak, https://doi.org/10.1111/gcb.14730 There is an inverse relationship between species adaptation potential (green/curved line) and refugial capacity (blue/light triangle). The ability of refugia species to adapt/acclimatize to future stressors (red/dark triangle), assuming this is within their physiological capabilities, depends on the refugial capacity of the refugia in which they live. The more effective a refugium, the lower the chance of its species adapting/acclimatizing.

Published
2019
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28. Monsoon control on channel avulsions in the Late Quaternary Congo Fan

Author

Picot, M., Marsset, T., Droz, L., Dennielou, B., Baudin, F., Hermoso, M., de Rafélis, M., Sionneau, T., Cremer, M., Laurent, D., Bez, M., Laboratoire Géosciences Océan (LGO), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Earth Sciences [Oxford], University of Oxford [Oxford], Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Max-Planck-Institut für Extraterrestrische Physik (MPE), TOTAL-Scientific and Technical Center Jean Féger (CSTJF), TOTAL FINA ELF, ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), University of Oxford, Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Centre scientifique et Technique Jean Feger (CSTJF)

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract

International audience

Published
2019

29. Millennial-scale Holocene hydrological changes in the northeast Atlantic: New insights from ‘ La Grande Vasière ’ mid-shelf mud belt

Author

Meryem Mojtahid, Frédérique Eynaud, Matthieu Durand, Aurélie Penaud, Hélène Howa, Pierre-Olivier Coste, Jean Nizou, Samuel Toucanne, Laboratoire de Planétologie et Géodynamique - Angers (LPG-ANGERS), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Bio-Indicateurs Actuels et Fossiles (BIAF), Université d'Angers (UA), Laboratoire Géosciences Océan (LGO), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Laboratoire Géodynamique et enregistrement Sédimentaire - Geosciences Marines (GM-LGS), and UMR 5805 Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC)

Subjects
010506 paleontology, Archeology, 010504 meteorology & atmospheric sciences, Scale (ratio), River runoff, stable isotopes, benthic foraminifera, 01 natural sciences, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 14. Life underwater, Holocene, ComputingMilieux_MISCELLANEOUS, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Earth-Surface Processes, Stable isotopes, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Global and Planetary Change, geography, geography.geographical_feature_category, Ecology, Continental shelf, Paleontology, Bay of Biscay, river runoff, Oceanography, 13. Climate action, [SDU]Sciences of the Universe [physics], Sedimentary rock, AMOC, NAO-like process, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Geology
Abstract

A mid- to late-Holocene paleohydrological reconstruction from the northeast Atlantic is proposed through the study of a high-resolution sedimentary record from the northern continental shelf of the Bay of Biscay (BoB). Three foraminiferal species dominate the assemblages with Rosalina globularis showing an overall decrease in absolute and relative abundances from ~7 to 0.4 cal. ka BP, whereas the opposite trend is observed for Cibicides refulgens and Lobatula. These long-term patterns are interpreted as a response to the overall cooling trend and/or the progressive deepening of the water column because of the relative sea-level (RSL) rise. Foraminiferal δ18O and grain-size analyses show a significant shift around 3.5–2.5 cal. ka BP toward a heavier isotopic signature and finer sediments. We mainly link this change to enhanced contribution of continental freshwaters and fine sediments after the near-stabilization of the RSL rise. By reducing coastal accommodation spaces, this led to a better channelization of river outflows and probably to the formation of the modern winter thermohaline front. Superimposed on these long-term patterns, our data highlight strong millennial-scale variability (1250-year peak). Such cyclicity is consistent with several records tracing changes in rainfall and storminess regimes in northern Europe, and the dynamics of the subpolar gyre (SPG). We suggest a millennial time-scale control of a NAO-like (North Atlantic Oscillation) climatic process modulating continental humidity (and the associated river discharges) and SPG dynamics through wind stress. Spectral analyses reveal an additional 500-year frequency peak implying a possible solar forcing.

Published
2018
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30. Observing Sea States

Author

Graham D. Quartly, Fabrice Collard, Johnny A. Johannessen, Val R. Swail, Fabrice Ardhuin, Romain Husson, Justin E. Stopa, Alexis Mouche, Ian R. Young, Bertrand Chapron, Robert E. Jensen, Marcello Passaro, Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), OceanDataLab, Collecte Localisation Satellites (CLS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National d'Études Spatiales [Toulouse] (CNES), Nansen Environmental and Remote Sensing Center [Bergen] (NERSC), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, lcsh:QH1-199.5, buoy, Ocean Engineering, Sea state, Aquatic Science, lcsh:General. Including nature conservation, geographical distribution, Oceanography, 01 natural sciences, altimeter, remote sensing, Wind wave, waves, 14. Life underwater, Real-time data, Altimeter, lcsh:Science, Physics::Atmospheric and Oceanic Physics, 0105 earth and related environmental sciences, Water Science and Technology, Remote sensing, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], Global and Planetary Change, swell, Buoy, 010604 marine biology & hydrobiology, Swell, ddc, 13. Climate action, Environmental science, Satellite, lcsh:Q, microseisms, Significant wave height, sea state, SAR
Abstract

International audience; Sea state information is needed for many applications, ranging from safety at sea and on the coast, for which real time data are essential, to planning and design needs for infrastructure that require long time series. The definition of the wave climate and its possible evolution requires high resolution data, and knowledge on possible drift in the observing system. Sea state is also an important climate variable that enters in air-sea fluxes parameterizations. Finally, sea state patterns can reveal the intensity of storms and associated climate patterns at large scales, and the intensity of currents at small scales. A synthesis of user requirements leads to requests for spatial resolution at kilometer scales, and estimations of trends of a few centimeters per decade. Such requirements cannot be met by observations alone in the foreseeable future, and numerical wave models can be combined with in situ and remote sensing data to achieve the required resolution. As today's models are far from perfect, observations are critical in providing forcing data, namely winds, currents and ice, and validation data, in particular for frequency and direction information, and extreme wave heights. In situ and satellite observations are particularly critical for the correction and calibration of significant wave heights to ensure the stability of model time series. A number of developments are underway for extending the capabilities of satellites and in situ observing systems. These include the generalization of directional measurements, an easier exchange of moored buoy data, the measurement of waves on drifting buoys, the evolution of satellite altimeter technology, and the measurement of directional wave spectra from satellite radar instruments. For each of these observing systems, the stability of the data is a very important issue. The combination of the different data sources, including numerical models, can help better fulfill the needs of users.

Published
2018
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31. Immunological and physiological responses of the periwinkle Littorina littorea during and after exposure to the toxic dinoflagellate Alexandrium minutum

Author

Patricia Mirella da Silva Scardua, Jean Louis Valentin, Gisela M. Figueiredo, Hélène Hégaret, Raquel A. F. Neves, Universidade Federal do Rio de Janeiro (UFRJ), Universidade Federal da Paraiba (UFPB), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), and ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)

Subjects
0106 biological sciences, Hemocytes, Health, Toxicology and Mutagenesis, Gastropoda, Alexandrium, Zoology, Histopathology, 010501 environmental sciences, Aquatic Science, medicine.disease_cause, 01 natural sciences, Harmful algal bloom (HAB), Condition index, Water column, Phagocytosis, parasitic diseases, Botany, medicine, Animals, 14. Life underwater, Paralytic shellfish poisoning, Gastropod, 0105 earth and related environmental sciences, Toxin accumulation, biology, Toxin, 010604 marine biology & hydrobiology, ACL, fungi, Dinoflagellate, Littorina, biology.organism_classification, medicine.disease, Dinoflagellida, Marine Toxins, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Marine toxin
Abstract

International audience; Species of the dinoflagellate genus Alexandrium produce phycotoxins responsible for paralytic shellfish poisoning. Blooms of Alexandrium minutum reach very high concentrations of vegetative cells in the water column; and when these blooms occur, large numbers of toxic cysts can be produced and deposited on sediments becoming available to benthic species. The present study investigated the potential effect of exposure to toxic cysts of A. minutum on the periwinkle Littorina littorea. Snails were exposed for nine days to pellicle cysts of toxic and non-toxic dinoflagellates, A. minutum and Heterocapsa triquetra, respectively, followed by six days of depuration while they were fed only H. triquetra. Toxin accumulation, condition index, immune and histopathological responses were analyzed. Histological alterations were also monitored in snails exposed to a harmful A. minutum bloom, which naturally occurred in the Bay of Brest. Snails exposed to toxic cysts showed abnormal behavior that seems to be toxin-induced and possibly related to muscle paralysis. Periwinkles accumulated toxins by preying on toxic cysts and accumulation appeared dependent on the time of exposure, increasing during intoxication period but tending to stabilize during depuration period. Toxic exposure also seemed to negatively affect hemocyte viability and functions, as ROS production and phagocytosis. Histological analyses revealed that toxic exposure induced damages on digestive organs of snails, both in laboratory and natural systems. This study demonstrates that an exposure to the toxic dinoflagellate A. minutum leads to sublethal effects on L. littorea, which may alter individual fitness and increase the susceptibility of snails to pathogens and diseases.

Published
2015
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