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| Registros recuperados: 34,909 | |
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| Neaud-masson, Nadine; Lemoine, Maud. |
| L'Ifremer exerce un appui scientifique et technique à la DGAL ainsi qu’aux services déconcentrés de l’Etat (DDi) relatif à la mise en œuvre du dispositif de surveillance sanitaire REPHYTOX (réseau de surveillance des phycotoxines dans les organismes marins). L’Assistance à Maîtrise d’OuvrAge (AMOA) de l’Ifremer sur le réseau REPHYTOX peut se décomposer en trois types d’activités : (i) un appui à l'élaboration du dispositif de surveillance sanitaire pertinent et répondant à la réglementation et à ses évolutions ; (ii) un soutien au maître d’ouvrage pour l’accompagnement des opérateurs chargés des prélèvements et des analyses des coquillages ; (iii) la gestion des données et leur diffusion. Les modalités de la surveillance assurée par le REPHYTOX sont... |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00454/56600/58258.pdf |
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| Nikolic, Natacha; Lauretta, Matthew; Patucca, Audrey; Morandeau, Gilles. |
| We compiled and analysed logbook data from the French trawl albacore fishery covering the period 1991–2015. The dataset comprised catch and effort data for the French fleet operating in the Bay of Biscay and Celtic Sea, as well as spatiotemporal and gear characteristics. Generalized linear modelling was used to model spatial, seasonal, environmental, and gear covariates of fleet CPUE rates. A long-term index of relative abundance is provided that can be integrated into the stock assessment of North Atlantic albacore. The analysis revealed higher albacore CPUE associated with relatively low sea surface temperature and distinct seasonal effects. The derived abundance trend for the French trawl fishery agreed with the estimated time series of stock abundance... |
| Tipo: Text |
Palavras-chave: Albacore; Catch; Atlantic; Trawl; Fisheries; Stock. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00461/57256/59283.pdf |
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| Picart, Stephane Saux; Tandeo, Pierre; Autret, Emmanuelle; Gausset, Blandine. |
| Machine learning techniques are attractive tools to establish statistical models with a high degree of non linearity. They require a large amount of data to be trained and are therefore particularly suited to analysing remote sensing data. This work is an attempt at using advanced statistical methods of machine learning to predict the bias between Sea Surface Temperature (SST) derived from infrared remote sensing and ground “truth” from drifting buoy measurements. A large dataset of collocation between satellite SST and in situ SST is explored. Four regression models are used: Simple multi-linear regression, Least Square Shrinkage and Selection Operator (LASSO), Generalised Additive Model (GAM) and random forest. In the case of geostationary satellites for... |
| Tipo: Text |
Palavras-chave: Machine learning; Systematic error; Sea surface temperature; Random forest. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00426/53797/54721.pdf |
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| Hori, Masakazu; Hamaoka, Hideki; Hirota, Masahito; Lagarde, Franck; Vaz, Sandrine; Hamaguchi, Masami; Hori, Juri; Makino, Mitsutaku. |
| Harmonizing coastal fisheries with water-quality improvement has become an essential factor for the sustainable use of coastal ecosystem services. Here, we present the scope of our study based on an interdisciplinary approach including ecological actions, socio-economic actions and socio-psychological actions. We chose to focus on the interaction between oyster aquaculture and seagrass vegetation as a typical ecological action using the coastal ecosystem complex (CEC) concept. Coastal organisms have adapted their traits to the environment over a long period of time, so that restoration of the CEC represents reconstruction of the original process of coastal production. Subtidal seagrass vegetation with intertidal oyster reefs is the original CEC in Japan,... |
| Tipo: Text |
Palavras-chave: Oyster aquaculture; Seagrass; Indigenous and local knowledge; Integrated coastal management. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00429/54019/57439.pdf |
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| Humeau, Corentin; Davies, Peter; Le Gac, Pierre Yves; Jacquemin, Frédéric. |
| Polyamide fibres are known to be sensitive to water, and this has limited their marine applications. However, their low stiffness and high strength could be attractive for shallow water mooring line ropes, particularly for floating wind turbines. Such applications require the influence of water on mechanical behaviour to be fully understood, and this paper presents results describing how water affects static and creep response of polyamide 6 fibre yarns. First, the effect of water on fibre Tg is quantified, then tensile behaviour is examined. Finally, a model based on Schapery’s non-linear creep analysis is identified for different humidity conditions. The results show that while moisture has a small effect on short-term tensile behaviour, long term... |
| Tipo: Text |
Palavras-chave: Aging; Moisture; Fibre; Creep; Viscoelastic model. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00460/57190/59251.pdf |
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| Kopp, Dorothee; Morandeau, Fabien; Mouchet, Maud; Vogel, Camille; Mehault, Sonia. |
| In the Bay of Biscay, the selective properties of otter trawls have mainly been studied with regard to single species. However, for bottom trawl multispecific fisheries targeting fish, it remains challenging to find a selective device capable of limiting catches of small individuals of several species without commercial losses. The present study focuses on an innovative technical solution to reduce catches of undersized individuals in a multispecies bottom trawl fishery in the Bay of Biscay. We tested a cylinder made of 100-mm diamond meshes turned at 90°, namely T90 inserted in the extension piece. We present the selectivity results obtained for six commercial species. This device allows the escape of small Solea solea, Trachurus trachurus and... |
| Tipo: Text |
Palavras-chave: Gear technology; Covered codend; Turned mesh; Escape; Discard ban. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00439/55026/56487.pdf |
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| Guyader, Olivier; Frangoudes, Katia; Kleiber, Danika. |
| Moored fish aggregating devices (MFADs) are used by small-scale fishers to access fish species difficult to harvest in large numbers. In the case of Guadeloupe (Caribbean area), the use of MFADs has increased considerably and this is causing congestion in these fishing areas and creating conflict between fishers. The aim of this article is to understand how informal fishing territories around the La Desirade Island were established and examine these territories through the lens of economic defendability theory. Results of semistructured interviews show that MFAD fishers display territoriality along MFAD tract lines forming quasi-privatized areas. Territoriality in this article is based on the following factors: the type of targeted resources, the cost of... |
| Tipo: Text |
Palavras-chave: Conflicts; Dolphinfish; Economic defendability; FADs quotas; Overcapacity. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00430/54151/56600.pdf |
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| David-grignot, Stephane; Lamlih, Achraf; Belhaj, Mohamed Moez; Kerzerho, Vincent; Azais, Florence; Soulier, Fabien; Freitas, Philippe; Rouyer, Tristan; Bonhommeau, Sylvain; Bernard, Serge. |
| In the context of biosensor as much as Built-In-Self Test (BIST), on-chip sine-wave signal generation is a recurring research topic. Considering the implementation constraints, it implies a trade-off between the amount of resources and the signal quality. An attractive solution consists in combining several digital signals to build this analog sine-wave. The objective of this paper is to give an analytic study of various potential digital-based solutions. Thanks to this study, we prove that the technique consisting in setting the phase shifts and various amplitude values of the square-wave signals is the most efficient approach. This study allows the selection of the optimal square-wave signal parameters to cancel low-order harmonics of the generated... |
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Palavras-chave: Harmonic cancelation; Sine-wave generation; On-chip signal generation. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00425/53678/54609.pdf |
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| Toullec, Jordan; Moriceau, Brivaela. |
| Diatom production is mainly supported by the dissolution of biogenic silica (bSiO(2)) within the first 200 m of the water column. The upper oceanic layer is enriched in dissolved and/or colloidal organic matter, such as exopolymeric polysaccharides (EPS) and transparent exopolymeric particles (TEP) excreted by phytoplankton in large amounts, especially at the end of a bloom. In this study we explored for the first time the direct influence of TEP-enriched diatom excretions on bSiO(2) dissolution. Twelve dissolution experiments on fresh and fossil diatom frustules were carried out on seawater containing different concentrations of TEP extracted from diatom cultures. Fresh diatom frustules were cleaned from the organic matter by low ash temperature, and... |
| Tipo: Text |
Palavras-chave: Exopolysaccharide; Diatom excretion; Diatomite; Chaetoceros muelleri; Biogenic silica; BSiO(2) dissolution; TEP. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00616/72795/72270.pdf |
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| Mairet, Francis. |
| Homeostasis is the capacity of living organisms to keep internal conditions regulated at a constant level, despite environmental fluctuations. Integral feedback control is known to play a key role in this behaviour. Here, I show that a feedback system involving transcriptional and post-translational regulations of the same executor protein acts as a proportional integral (PI) controller, leading to enhanced transient performances in comparison with a classical integral loop. Such a biomolecular controller-which I call a level and activity-PI controller (LA-PI)-is involved in the regulation of ammonium uptake by Escherichia coli through the transporter AmtB. The P-II molecules, which reflect the nitrogen status of the cell, inhibit both the production of... |
| Tipo: Text |
Palavras-chave: Homeostasis; Perfect adaptation; Regulatory motif; Transcriptional and post-translational regulations. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00434/54598/55968.pdf |
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| Tenorio, Manuel J.; Monnier, Eric; Puillandre, Nicolas. |
| Although cone snails are among the most studied group of gastropods, new species are still regularly described. Here, we focus on Afonsoconus Tucker & Tenorio, 2013, a lineage that includes only two species from the Indo-Pacific Ocean. The analysis of molecular (partial mitochondrial cox1 gene sequences) and morphological (shell and radular tooth) characters revealed that the samples collected by dredging in deep water during a recent expedition carried out in the Mozambique Channel are different from the samples collected in the Pacific Ocean. We thus introduce here a new species, Afonsoconus crosnieri sp. nov., from the SW Indian Ocean including records from the Mozambique Channel, the Comoros and Glorieuses Islands, Madagascar, South Africa and... |
| Tipo: Text |
Palavras-chave: Mitochondrial cox1 gene; Conidae; Afonsoconus; South-West Indian Ocean. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00465/57663/59859.pdf |
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| Guieu, Cecile; Bonnet, Sophie; Petrenko, Anne; Menkes, Christophe; Chavagnac, Valerie; Desboeufs, Karine; Maes, Christophe; Moutin, Thierry. |
| In the Western Tropical South Pacific, patches of high chlorophyll concentrations linked to the occurrence of N2-fixing organisms are found in the vicinity of volcanic islands. The survival of these organisms relies on a high bioavailable iron supply whose origin and fluxes remain unknown. Here, we measured high dissolved iron (DFe) concentrations (up to 66 nM) in the euphotic layer, extending zonally over 10 degrees longitude (174 E−175 W) at ∼20°S latitude. DFe atmospheric fluxes were at the lower end of reported values of the remote ocean and could not explain the high DFe concentrations measured in the water column in the vicinity of Tonga. We argue that the high DFe concentrations may be sustained by a submarine source, also characterized by... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00444/55564/57174.pdf |
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| Humeau, Corentin; Davies, Peter; Jacquemin, Frederic. |
| The coupling between tensile stress and water diffusion in composites represents a major issue in many marine applications. Even if these two behaviours are well documented as separate subjects, there are still very few data on fully coupled mechanisms. The aim of this study is to understand what governs the coupled behaviour, by investigating the water diffusion in carbon/epoxy. The coupling is first evaluated on neat resin samples to characterise the matrix behaviour. Then the study focuses on composites with two types of woven fibre orientation: one at ±45°, in order to understand the coupling effects on materials loaded away from the reinforcement direction and another quasi-isotropic to obtain properties along the fibres. For each material the same... |
| Tipo: Text |
Palavras-chave: Composite; Moisture diffusion; Static tensile stress; Coupled behaviour. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00416/52788/53687.pdf |
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| Ker, Stephan; Le Gonidec, Yves. |
| Multiscale seismic attributes based on the wavelet transform properties have been recently introduced and successfully applied to identify the geometry of a complex seismic reflector in an elastic medium. In the present paper, we extend this quantitative approach to anelastic media where intrinsic attenuation modifies the seismic attributes and thus requires a specific processing to retrieve them properly. The method assumes both an attenuation linearly dependent with the seismic wave frequency and a seismic source wavelet approximated with a Gaussian derivative function. We highlight a quasi-conservation of the Gaussian character of the wavelet during its propagation. We show that this shape can be accurately modeled by a Gaussian derivative function... |
| Tipo: Text |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00409/52034/52700.pdf |
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| Galand, Pierre E.; Pereira, Olivier; Hochart, Corentin; Auguet, Jean-christophe; Debroas, Didier. |
| Marine microbes have tremendous diversity, but a fundamental question remains unanswered: why are there so many microbial species in the sea? The idea of functional redundancy for microbial communities has long been assumed, so that the high level of richness is often explained by the presence of different taxa that are able to conduct the exact same set of metabolic processes and that can readily replace each other. Here, we refute the hypothesis of functional redundancy for marine microbial communities by showing that a shift in the community composition altered the overall functional attributes of communities across different temporal and spatial scales. Our metagenomic monitoring of a coastal northwestern Mediterranean site also revealed that diverse... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00459/57118/59050.pdf |
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| Registros recuperados: 34,909 | |
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