A Lagrangian Method to Isolate the Impacts of Mixed Layer Subduction on the Meridional Overturning Circulation in a Numerical Model - Thomas, Matthew; Treguier, Anne-marie; Blanke, Bruno; Deshayes, Julie; Voldoire, Aurore
Large differences in the Atlantic meridional overturning circulation (AMOC) exhibited between the available ocean models pose problems as to how they can be interpreted for climate policy. A novel Lagrangian methodology has been developed for use with ocean models that enables a decomposition of the AMOC according to its source waters of subduction from the mixed layer of different geographical regions. The method is described here and used to decompose the AMOC of the Centre National de Recherches Météorologiques (CNRM) ocean model, which is approximately 4.5 Sv (1 Sv = 106 m3 s−1) too weak at 26°N, compared to observations....
Argos-3 Satellite Communication System: Implementation on the Arvor Oceanographic Profiling Floats - Andre, Xavier; Moreau, Bertrand; Le Reste, Serge
The scientific community observes the ocean for applications in the fields of oceanography and climate research. In order to recover in situ data, more than 3,000 profiling floats are operated in the framework of the Argo Program. Each float performs cycles between the sea surface and a depth of 2,000 meters. Scientific data are gathered while the float is travelling upward from the depths of the oceans, and are then transmitted via a satellite communication system at the end of each cycle. During its time at the surface, mainly dedicated to transmissions, the float is vulnerable and subject to drift,...
Population structure enhances perspectives on regional management of the western Indian Ocean green turtle - Bourjea, Jerome; Mortimer, Jeanne A.; Garnier, Julie; Okemwa, Gladys; Godley, Brendan J.; Hughes, George; Dalleau, Mayeul; Jean, Claire; Ciccione, Stephane; Muths, Delphine
To refine our understanding of the spatial structure of the green turtle (Chelonia mydas) populations in the South West Indian Ocean (SWIO), we analysed patterns of mitochondrial DNA (396 base pairs control region fragment) variation among 171 samples collected at five distinct locations (Kenya, Northern Mozambique, and three locations in the Republic of Seychelles: the Granitic, Amirantes, and Farquhar groups) and compared them to genetic data (n = 288), previously collected from 10 southern locations in the SWIO. We also analysed post-nesting satellite tracks (n = 4) from green turtles nesting in the Amirantes group. Pairwise comparisons of haplotype frequencies...
Holocene turbidites record earthquake supercycles at a slow-rate plate boundary - Ratzov, Gueorgui; Cattaneo, Antonio; Babonneau, Nathalie; Deverchere, Jacques; Yelles, Karim; Bracene, Rabah; Courboulex, Francoise
Ongoing evidence for earthquake clustering calls for records of numerous earthquake cycles to improve seismic hazard assessment, especially where recurrence times overstep historical records. We show that most turbidites emplaced at the Africa-Eurasia plate boundary off west Algeria over the past ∼8 k.y. correlate across sites fed by independent sedimentary sources, requiring a regional trigger. Correlation with paleoseismic data inland and ground motion predictions support that M ∼7 earthquakes have triggered the turbidites. The bimodal distribution of paleo-events supports the concepts of earthquake supercycles and rupture synchronization between nearby faults: 13 paleo-earthquakes underpin clusters of 3–6 events with recurrence intervals...
A European epidemiological survey of Vibrio splendidus clade shows unexplored diversity and massive exchange of virulence factors - Nasfi, H.; Travers, Marie-agnes; De Lorgeril, Julien; Habib, C.; Sannie, T.; Sorieul, L.; Gerard, J.; Avarre, J. C.; Haffner, Philippe; Tourbiez, Delphine; Renault, Tristan; Furones, D.; Roque, A.; Pruzzo, C.; Cheslett, D.; Gdoura, R.; Vallaeys, T.
The Vibrio splendidus clade has previously been associated with epidemic outbreaks of various aquatic animals, as in the case of the cupped oyster, Crassostrea gigas. To investigate whether involved strains could present a clonal origin and to identify possible alternative background carriage animals or zooplankton, a large epidemiological survey was conducted on isolates of the splendidus clade. For this purpose, Vibrio strains were isolated from various samples including oysters, mussels, sediments, zooplankton, and sea water on the basis of a North/South gradient of the European sea water zone (Ireland, The Netherlands, France, Italy, and Spain). A total of 435 isolates...
Application of a new algorithm using Doppler information to retrieve complex wind fields over the Black Sea from ENVISAT SAR images - Alpers, Werner; Mouche, Alexis; Horstmann, Jochen; Ivanov, Andrei Yu.; Barabanov, Vladyslav S.
Several algorithms have been proposed to retrieve near-surface wind fields from C-band synthetic aperture radar (SAR) images acquired over the ocean. They mainly differ in the way they retrieve the wind direction. Conventionally, the wind direction is taken from atmospheric models or is extracted from the linear features sometimes visible in SAR images. Recently, a new wind retrieval algorithm has been proposed, which also includes the Doppler shift induced by motions of the sea surface. In this article, we apply three wind retrieval algorithms, including the one using Doppler information, to three complex wind events encountered over the Black Sea...
Influence of one selected Tisochrysis lutea strain rich in lipids on Crassostrea gigas larval development and biochemical composition - Da Costa, F.; Petton, Bruno; Mingant, Christian; Bougaran, Gael; Rouxel, Catherine; Quere, Claudie; Wikfors, Gary H.; Soudant, Philippe; Robert, Rene
Effects of a remarkably high overall lipid Tisochrysis lutea strain (T+) upon gross biochemical composition, fatty acid (FA), sterol and lipid class composition of Crassostrea gigas larvae were evaluated and compared with a normal strain of Tisochrysis lutea (T) and the diatom Chaetoceros neogracile (Cg). In a first experiment, the influence of different single diets (T, T+ and Cg) and a bispecific diet (TCg) was studied, whereas, effects of monospecific diets (T and T+) and bispecific diets (TCg and T+Cg) were evaluated in a second experiment. The strain T+ was very rich in triglycerides (TAG: 93–95% of total neutral lipids),...
An autoregressive model to describe fishing vessel movement and activity - Gloaguen, Pierre; Mahevas, Stephanie; Rivot, Etienne; Woillez, Mathieu; Guitton, Jerome; Vermard, Youen; Etienne, Marie-pierre
The understanding of the dynamics of fishing vessels is of great interest to characterize the spatial distribution of the fishing effort and to define sustainable fishing strategies. It is also a prerequisite for anticipating changes in fishermen's activity in reaction to management rules, economic context, or evolution of exploited resources. Analyzing the trajectories of individual vessels offers promising perspectives to describe the activity during fishing trips. A hidden Markov model with two behavioral states (steaming and fishing) is developed to infer the sequence of non-observed fishing vessel behavior along the vessel trajectory based on Global Positioning System (GPS) records. Conditionally...
Meteorological data from the EMSO-Azores seafloor observatory, 2012-2013 - Legrand, Julien; Sarradin, Pierre-marie; Cannat, Mathilde
This dataset contains the meteorological parameters (mean wind speed, temperature in °C and atmospheric pressure in mbar) acquired between Jannuary 2012 and December 2013 (n=332) using the Furuno Rowind+, mounted at the top of BOREL superstructure (data acquired every 6 hours).
Iridium GPS 2 data from the EMSO-Azores observatory, 2012-2013 - Legrand, Julien; Sarradin, Pierre-marie; Cannat, Mathilde
This dataset contains the GPS positions of the EMSO-Azores transmission buoy BOREL acquired between Jannuary 2012 and december 2013 using the Iridium/GPS modem 2 (data acquired every 6 hours).
Iridium GPS 1 data from the EMSO-Azores observatory, 2012-2013 - Legrand, Julien; Sarradin, Pierre-marie; Cannat, Mathilde
This dataset contains the GPS positions of the EMSO-Azores transmission buoy BOREL acquired between Jannuary 2012 and december 2013 using the Iridium/GPS modem 1 (data acquired every 6 hours).
COSTOF, technical data from SeaMoN West, node of the EMSO-Azores observatory, 2014-2015 - Legrand, Julien; Sarradin, Pierre-marie; Cannat, Mathilde
This dataset contains technical parameters (Voltage in V, current in mA, energy in Ah, internal pressure in mbar, water leak detection) acquired between July 2014 and April 2015 by the COSTOF (COmmunication and STOrage Front-end), which is the Electronic core of SeaMoN West, the bottom station of EMSO-Azores dedicated to geophysical observations (data acquired every 6 hours).
Meteorological data from the EMSO-Azores seafloor observatory, 2014-2015 - Legrand, Julien; Sarradin, Pierre-marie; Cannat, Mathilde
This dataset contains the meteorological parameters (mean wind speed, temperature in °C and atmospheric pressure in mbar) acquired between July 2014 and April 2015 using the Furuno Rowind+, mounted at the top of BOREL superstructure (data acquired every 6 hours).
Iridium GPS 2 data from the EMSO-Azores observatory, 2014-2015 - Legrand, Julien; Sarradin, Pierre-marie; Cannat, Mathilde
This dataset contains the GPS positions of the EMSO-Azores transmission buoy BOREL acquired between July 2014 and April 2015 using the Iridium/GPS modem 2 (data acquired every 6 hours).
Iridium GPS 1 data from the EMSO-Azores observatory, 2014-2015 - Legrand, Julien; Sarradin, Pierre-marie; Cannat, Mathilde
This dataset contains the GPS positions of the EMSO-Azores transmission buoy BOREL acquired between July 2014 and April 2015 using the Iridium/GPS modem 1 (data acquired every 6 hours).
Towards the development of clonal lines in the European sea bass (Dicentrarchus labrax L.): application of uniparental reproduction techniques with an insight into sea bass eggs - Colleter, Julie
Clonal lines are a powerful scientific tool for improved genetic characterization of organisms used in research. Inbred fish lines can be produced in only two generations using uniparental reproduction techniques. Androgenesis, achieved with variable success in several freshwater species, has been attempted in the European sea bass (Dicentrarchus labrax L), a marine fish of commercial and scientific interest. The low yields of progenies inheriting only the paternal genome after UV-irradiation of eggs led to considerations on the occurrence of UV screening compounds in pelagic eggs. Mycosporine-like amino acids and gadusol were found in many marine and freshwater organisms, but their...
In-depth analyses of deep subsurface sediments using 454-pyrosequencing reveals a reservoir of buried fungal communities at record-breaking depths - Redou, Vanessa; Ciobanu, Maria Cristina; Pachiadaki, Maria G.; Edgcomb, Virginia; Alain, Karine; Barbier, Georges; Burgaud, Gaetan
The deep subseafloor, extending from a few centimeters below the sediment surface to several hundred meters into sedimentary deposits, constitutes the deep biosphere and harbors an unexpected microbial diversity. Several studies have described the occurrence, turnover, activity and function of subseafloor prokaryotes; however, subsurface eukaryotic communities still remain largely underexplored. Ribosomal RNA surveys of superficial and near-surface marine sediments have revealed an unexpected diversity of active eukaryotic communities, but knowledge of the diversity of deep subseafloor microeukaryotes is still scarce. Here, we investigated the vertical distribution of DNA and RNA fungal signatures within subseafloor sediments of the Canterbury basin (New...
Modeled mixed-layer salinity balance in the Gulf of Guinea: seasonal and interannual variability - Da-allada, Casimir Yelognisse; Du Penhoat, Yves; Jouanno, Julien; Alory, Gael; Hounkonnou, Norbert Mahouton
A regional numerical simulation and observations were used to investigate the various processes controlling mixed-layer salinity balance on seasonal and interannual time scales in the Gulf of Guinea. Processes were quantified using a mixed-layer salt budget. Model results correctly reproduced the mean, phase, and amplitude of observed seasonal near-surface salinity. The results indicated that on seasonal time scales, the mixed-layer salinity balance differed from one region to another. The surface salinity seasonal cycle was characterized by strong salinization during May for coastal areas north and south of the equator. Model results suggested that vertical mixing controls the mixed-layer salinity increase...
Predation has no competition: factors influencing space and resource use by echinoids in deep-sea coral habitats, as evidenced by continuous video transects - Stevenson, Angela; Mitchell, Fraser J. G.; Davies, Jaime S.
Predation and competition are highly influential factors determining space use in foraging animals, and ultimately contribute to the spatial heterogeneity observed within habitats. Here we investigated the influence of competition and predation on space and resource use via continuous video transect observations – a tool that has not previously been employed for this purpose. This study therefore also evaluates video data as a pragmatic tool to study community interactions in the deep sea. Observations were compiled from 15 video transects spanning five submarine canyons in the Bay of Biscay, France. Substrate choice, positioning on the coral, echinoid aggregate size, and...
Tectonic and sedimentary controls on widespread gas emissions in the Sea of Marmara: Results from systematic, shipborne multibeam echo sounder water column imaging - Dupre, Stephanie; Scalabrin, Carla; Grall, Celine; Augustin, Jean-marie; Henry, Pierre; Sengor, A. M. Celal; Goeruer, Naci; Cagatay, M. Namik; Geli, Louis
Understanding of the evolution of fluid-fault interactions during earthquake cycles is a challenge that acoustic gas emission studies can contribute. A survey of the Sea of Marmara using a shipborne, multibeam echo sounder, with water column records, provided an accurate spatial distribution of offshore seeps. Gas emissions are spatially controlled by a combination of factors, including fault and fracture networks in connection to the Main Marmara Fault system and inherited faults, the nature and thickness of sediments (e.g., occurrence of impermeable or gas-bearing sediments and landslides), and the connectivity between the seafloor and gas sources, particularly in relation to the...