Éditeur(s) : Université des Antilles Études caribéennes
Résumé : El turismo náutico se concibe como un segmento estratégico para el desarrollo turístico de España y sus destinos costeros. En Canarias existe una apuesta pública por la especialización del Archipiélago y su reposicionamiento como destino líder europeo de escala en el Atlántico, por las múltiples cualidades naturales que posee la región para el deporte náutico, y su posición geográfica estratégica en el cruce desde Europa hacia el Caribe. Así, se viene planteando una renovación y desarrollo del sector de la náutica de recreo y el turismo de yates, con estrategias enfocadas a la diversificación y el crecimiento. Los altos costes sociales y medioambientales asociados a este tipo de desarrollo justifican la necesidad de una mayor atención académica, que permita comprender las particularidades y complejidades de la actividad y este mercado turístico. En la misma medida en que esta actividad es vista como un factor de riesgo para el medioambiente, la comunidad local y la franja litoral, también son crecientes las preocupaciones y sensibilidad por parte de los turistas hacia estos fenómenos. Dada la carencia de investigaciones en el área, este estudio se propone identificar los determinantes de la satisfacción de los navegantes europeos con los puertos de escala de Canarias. Como resultado de encuestar a 185 navegantes europeos durante su escala en seis puertos deportivos del archipiélago en 2014 y 2015, y la validación de un sistema de ecuaciones estructurales, se ha podido demostrar, entre otros aspectos, que existe una predilección en el mercado de navegantes europeos por presenciar esfuerzos y políticas de gestión ambiental sostenible en las marinas, siendo éste un factor determinante de su satisfacción. Los hallazgos permiten elaborar una serie de recomendaciones a gestores y operadores turísticos del sector, en aras de contribuir al diseño de estrategias que garanticen un desarrollo más sostenible y razonable de la actividad, basados en el efecto positivo que producen estas estrategias en la demanda, y el potencial valor de diferenciación turística que otorga, en el entorno competitivo del sector.
The nautical activiity has great potential for the socio-economic development of tourism. In Spain, the sector is a priority concern, especially for the Canary Islands, which show a clear commitment to specialise and reposition the destination as a top quality nautical destination on a European level. These aspects, together with the prior experience and tradition these islands have as a stopover destination for vessels in the Atlantic, when crossing Europe towards the Caribbean, represent strengths that have not yet been taken advantage of in the archipelago’s attempt to move away from its image as a traditional sun and beach destination. The Governmental Authorities in the Canary Islands have clear strategies in place to promote the yachting tourism growth. However, renewing the sector is believed to be a difficult process because of the large number of factors that interact within the same. This is a phenomenon of sufficient social and environmental significance to justify academic attention. This research analyses therefore the determinants of the European yachtsmen´s satisfaction with the ports of call of the Canary Islands. Data results of questioning 185 European yachtsmen crossing the Atlantic during 2014 and 2015 reveal that, among other aspects, proper environmental management of marinas leads to an increasing yachtsmen´s satisfaction. The findings provide the opportunity for developing recommendations for tourism managers and practitioners, in the attempt to contribute to a more sustainable and reasoned development and growth in the sector. Based on the current preferences of the European market of yachtsmen, it is possible to assure that environmental and social responsibility policies are a key differentiation factor for the competitiveness of the sector.
Canaries

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.10584
http://journals.openedition.org/etudescaribeennes/10584

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Everyone is subject to environmental exposures from various sources, with negative health impacts (air, water and soil contamination, noise, etc.or with positive effects (e.g. green space). Studies considering such complex environmental settings in a global manner are rare. We propose to use statistical factor and cluster analyses to create a composite exposure index with a data-driven approach, in view to assess the environmental burden experienced by populations. We illustrate this approach in a large French metropolitan area. The study was carried out in the Great Lyon area (France, 1.2 M inhabitants) at the census Block Group (BG) scale. We used as environmental indicators ambient air NO2 annual concentrations, noise levels and proximity to green spaces, to industrial plants, to polluted sites and to road traffic. They were synthesized using Multiple Factor Analysis (MFA), a data-driven technique without a priori modeling, followed by a Hierarchical Clustering to create BG classes. The first components of the MFA explained, respectively, 30, 14, 11 and 9% of the total variance. Clustering in five classes group: (1) a particular type of large BGs without population; (2) BGs of green residential areas, with less negative exposures than average; (3) BGs of residential areas near midtown; (4) BGs close to industries; and (5) midtown urban BGs, with higher negative exposures than average and less green spaces. Other numbers of classes were tested in order to assess a variety of clustering. We present an approach using statistical factor and cluster analyses techniques, which seem overlooked to assess cumulative exposure in complex environmental settings. Although it cannot be applied directly for risk or health effect assessment, the resulting index can help to identify hot spots of cumulative exposure, to prioritize urban policies or to compare the environmental burden across study areas in an epidemiological framework.Journal of Exposure Science and Environmental Epidemiology advance online publication, 24 September 2014; doi:10.1038/jes.2014.66.
ISSN: 1559-0631

hal-01069587
https://hal.archives-ouvertes.fr/hal-01069587
https://hal.archives-ouvertes.fr/hal-01069587/document
https://hal.archives-ouvertes.fr/hal-01069587/file/Article_multiexpo_20140708_c.pdf
DOI : 10.1038/jes.2014.66

Éditeur(s) : HAL CCSD
Résumé : Geothermal energy is considered as a green and infinite energy source at human scale. Currently, the yield of geothermal power plants is limited to temperatures of the operating fluid which 350 °C. From tectonic and volcanic activity at mid-ocean ridges, Iceland is a location where supercritical fluid extraction (T> 375 °C) can considered for the near future. Exploiting such fluids could theoretically multiply by a factor of ten the electrical power delivered by geothermal wells. Can such fluids circulate at the base of brittle oceanic crust? This work investigates the petrophysical properties of basalts in order to constrain geophysical observations in Iceland and predict the behavior of very high temperature geo-hydrothermal reservoirs. The first approach consisted in studying the physical properties of rocks that have hosted deep hydrothermal circulations at oceanic ridges. The study of these rocks at ODP Site 1256 shows that the porosity measured both in the field and in the lab is associated with amphibolite facies alteration minerals (T> 500 ° C). The second approach was to recreate in the laboratory the conditions of pressure, temperature and pore fluid pressure of high temperature to supercritical hydrothermal systems to predict the mechanical and electrical properties of basalts under these conditions. The mechanical results indicate that the brittle/ductile transition occurs at a temperature of about 550° C, where a strong permeability decrease is expected. The implementation and calibration of a new cell for measuring electrical conductivity at high temperature provide the first results for the interpretation of geophysical data. When applied to basaltic crustal conditions in Iceland, these results indicate that hydrothermal fluids could circulate, at least temporarily, in a supercritical state up to 5 km depth.
La géothermie est considérée comme une source d'énergie propre et inépuisable à échelle humaine. Actuellement, le rendement des centrales géothermiques est limité à l'exploitation de fluides de températures inférieures à 350 °C. L'association de l'activité tectonique et volcanique aux dorsales océaniques fait de l'Islande un lieu où l'extraction de fluides supercritiques (T> 375 °C) peut être envisagée. Cette exploitation pourrait multiplier par dix la puissance électrique délivrée par le système géothermal. Ces fluides peuvent-ils circuler dans la croûte océanique ? Ce travail propose de contraindre les observations géophysiques et de prédire le fonctionnement des réservoirs géo-hydrothermaux de très haute température par l'étude des propriétés physiques des basaltes. La première approche est focalisée sur l'étude de roches ayant accueilli une circulation hydrothermale par le passé. L'étude de ces roches au site ODP 1256, montre que leur porosité est associée à la présence de minéraux d'altération hydrothermale du facies amphibolite (T> 500 °C). La seconde approche a consisté à recréer, en laboratoire, les conditions des systèmes hydrothermaux, à très haute température, afin de prédire les propriétés mécaniques et électriques des basaltes dans ces conditions. Les résultats mécaniques indiquent que la transition fragile/ductile, souvent associée à une forte décroissance de perméabilité, intervient à une température d'environ 550 °C. La mise en place d'une cellule de mesure de la conductivité électrique de haute température a fourni les premiers résultats utiles à l'analyse des données géophysiques. Appliqués aux conditions de la croûte basaltique Islandaise, ces résultats indiquent que des fluides hydrothermaux pourraient circuler au moins transitoirement à l'état supercritique jusqu'à ~ 5 km de profondeur.
https://tel.archives-ouvertes.fr/tel-00591798

tel-00591798
https://tel.archives-ouvertes.fr/tel-00591798
https://tel.archives-ouvertes.fr/tel-00591798/document
https://tel.archives-ouvertes.fr/tel-00591798/file/THESE_MV_pro.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
Background: Everyone is subject to environmental exposures from various sources, with negative health impacts (air, water and soil contamination, noise...) or with positive effects (e.g. green space). Studies considering such complex environmental settings in a global manner are rare.Aims: We propose to use data mining techniques to create a composite exposure index with a data-driven approach, in view to assess the environmental burden experienced by populations. We illustrate this approach on a large French metropolitan area.Methods: The study was carried out in the Great Lyon area (France, 1,260,348 inhabitants in 2007, 527 km²) at the census block group (BG) scale. Indicators on NO2 annual concentrations, noise levels, proximity to green spaces and to industrial plants, and road traffic were synthetized using Multiple Factor Analysis (MFA), which allows to explore the relations between exposures and BGs without a priori knowledge, and to synthetize indicators of different types. Hierarchical clustering was then used to create BG classes. Results: The four first components of the MFA explained respectively 23, 14, 13 and 12% of the total variance. Clustering in 3 classes group: 1) BGs far from industries, greener and with less noise and air pollution than the average; 2) BGs close to industries with less green spaces and air pollution than the average; and 3)BGs far from industries but with higher levels of noise, air pollution and traffic. Greater numbers of classes were tested in order to assess a variety of clustering.Conclusions: We present a data driven approach using data mining techniques, which seem overlooked for cumulative exposure assessment in complex environmental settings. Although it cannot be applied directly for risk or health effect assessment, the resulting index can help to identify hot spots of cumulative exposure, to prioritize urban policies or to compare the environmental burden across study areas in an epidemiological framework.
Environment and Health – Bridging South, North, East and West. Conference of ISEE, ISES and ISIAQ.
Basel, Switzerland

hal-01432884
https://hal.archives-ouvertes.fr/hal-01432884
https://hal.archives-ouvertes.fr/hal-01432884/document
https://hal.archives-ouvertes.fr/hal-01432884/file/Poster_2013_ISEE_20130711.pdf

Éditeur(s) : HAL CCSD PubMed
Résumé : International audience
The aim of this study was to measure the heart rate (HR) response of eight elite water polo players during the four 7-min quarters of the game and to check for relationships with the physiological parameters of performance ( ·VO2max, Th1vent, Th2vent). Each athlete performed a ·VO2max treadmill test and played a water polo game wearing a heart rate monitor. The game fatigue index was calculated as the ratio of the fourth-quarter HR to the first-quarter HR: HR4/HR1. The results showed a slight decrease in fourth-quarter HR compared with the first quarter, with the mean four-quarter HR equal to 79.9 ± 4.2% of HRmax. Stepwise multiple regression analysis showed ·VO2max to be the main explanatory factor of game intensity, i.e. game HR expressed in %HRreserve (R=0.88, P<0.01). We observed that higher aerobic capacity resulted in higher game intensity. We also observed a decrease in the playing intensity in the fourth quarter compared with the first, likely due to very high game involvement. We concluded that high aerobic capacity seems necessary to ensure high game intensity in water polo. This suggests that coaches should encourage their athletes to reach a minimum level of ·VO2max and that HR monitoring could be of great interest in the control of water polo training sessions.
ISSN: 0860-021X

hal-01158208
https://hal.univ-antilles.fr/hal-01158208
DOI : 10.5604/20831862.1083277

Éditeur(s) : Gauthier-Villars
Résumé : Fish communities from two lagoon ecosystems, Ria Formosa (Portugal) and Grand Cul-de-Sac Marin (Guadeloupe), show interesting similarities of spatial and temporal organization. On the temporal scale, three community changes are observed in both systems, corresponding to massive arrivals and/or departures of migratory species. However, these migrations are more conspicuous in the Ria Formosa than in the Grand Cul-de-Sac Marin. On a spatial scale, the community structure is also largely determined by migratory species, whose abundance is a factor of homogenization. This is clearly observed in Ria Formosa, where the lagoon selection applies on a regional scale. Conversely, the community of sedentary fish identifies remarkable stations affected by chronic aggressions such as tourism or pollution. An explicative analysis, comprising a discriminant analysis and multiple regressions was realized on the data collected in the Grand Cul-de-Sac Marin. This analysis made it possible to determine the important environmental descriptors in the two complementary processes involved in recruitment: migrant availability, which determines the temporal organization of the fish assemblage. These migrations are explained by water temperature and salinity, two descriptors controlled by climatic conditions; the settlement process, which determines the spatial organization of the fish assemblage. This is explained by habitat descriptors such as visibility and turtlegrass blade length, or trophic descriptors, such as primary production, zooplankton density or nitrate concentration.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1993 , Vol. 16 , N. 3 , P. 291-301

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00099/21056/18682.pdf
http://archimer.ifremer.fr/doc/00099/21056/

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Fish mucus has important biological and ecologicalroles such as defense against fish pathogens andchemical mediation among several species. A non-targetedliquid chromatography–mass spectrometry metabolomicapproach was developed to study gill mucus of eight butterflyfishspecies in Moorea (French Polynesia), and theinfluence of several fish traits (geographic site and reefhabitat, species taxonomy, phylogeny, diet and parasitismlevels) on the metabolic variability was investigated. Abiphasic extraction yielding two fractions (polar and apolar)was used. Fish diet (obligate corallivorous, facultativecorallivorous or omnivorous) arose as the main driver ofthe metabolic differences in the gill mucus in both fractions,accounting for 23% of the observed metabolic variabilityin the apolar fraction and 13% in the polar fraction.A partial least squares discriminant analysis allowed us toidentify the metabolites (variable important in projection,VIP) driving the differences between fish with differentdiets (obligate corallivores, facultative corallivores andomnivorous). Using accurate mass data and fragmentationdata, we identified some of these VIP as glycerophosphocholines,ceramides and fatty acids. Level of monogeneangill parasites was the second most important factor shapingthe gill mucus metabolome, and it explained 10% of themetabolic variability in the polar fraction and 5% in theapolar fraction. A multiple regression tree revealed that themetabolic variability due to parasitism in the polar fractionwas mainly due to differences between non-parasitized andparasitized fish. Phylogeny and butterflyfish species werefactors contributing significantly to the metabolic variabilityof the apolar fraction (10 and 3%, respectively) buthad a less pronounced effect in the polar fraction. Finally,geographic site and reef habitat of butterflyfish species didnot influence the gill mucus metabolome of butterflyfishes.
ISSN: 0722-4028

hal-01563312
https://hal-univ-perp.archives-ouvertes.fr/hal-01563312
DOI : 10.1007/s00338-017-1554-0

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : L’exploitation commerciale des produits forestiers non ligneux a animé et anime encore au plan international les débats sur la gestion durable des forêts, notamment par son apport en matière de conservation, d’amélioration des conditions d’existence des populations locales et de gestion participative. Cependant, l’exploitation commerciale des PFNL soulève la problématique de la durabilité tant au plan écologique, économique que sociopolitique. La présente recherche traite de cette problématique en prenant comme PFNL d’illustration le raphia dans la forêt marécageuse Hlanzoun. Elle vise à analyser la durabilité socio-économique et environnementale de l’exploitation du raphia dans la forêt marécageuse « Hlanzoun ». La méthodologie utilisée est une combinaison d’approches quantitatives et qualitatives. Les outils d’analyse de données utilisés sont entre autre, la statistique descriptive, l’analyse filière des revenus d’exploitation et des valeurs ajoutées et l’analyse du système socio-écologique. Nos résultats montrent que le raphia est une plante à usages multiples. Que ce soit les feuilles, les fibres, la sève ou le tronc, tout ou presque peut être valorisé sur le raphia. Au niveau des villages riverains du Hlanzoun l’exploitation de la sève du raphia et sa transformation en alcool alimentaire est de loin le type d’usage qui procure le plus de revenu malgré le fait que les autres types d’usages mobilisent un nombre plus important d’acteurs. L’exploitation commerciale de ce PFNL se déploie suivant une organisation relativement simple et avec des caractéristiques propres à la plupart des activités de la petite production marchande des économies sous-développées en crise. Cette exploitation est essentiellement articulée autour des coupeurs/collecteurs, des intermédiaires commerciaux, des agents de transformation/conditionnement et des consommateurs des produits finis. La contribution annuelle totale de la filière raphia au développement a été estimée à 192 429 633 Fr. CFA (environ 385 000 dollar) et les revenus d’exploitation de tous les acteurs ont un signe positif malgré le faible niveau de technologie et de formation. Le raphia apporte donc des revenus relativement importants aux divers acteurs en dépit des handicaps de la filière et du déficit d’équité dans la répartition des richesses produites. Au plan de la gouvernance, on note un déficit d’instances, de règles et de procédures, dont l’effectivité et la légitimité sont clairement établies. Cet état de chose laisse le parc à raphia dans un régime d’accès « libre » mais seulement pour les riverains ; nous nous retrouvons donc en présence d’un système de cueillette, caractérisé par l’exploitation de plants immatures et la surexploitation, mettant en péril la capacité de renouvellement de la ressource et même l’avenir de la filière. On note cependant un effort de contrôle de l’accès des non riverains et des tentatives d’adaptation des riverains. En effet, le nombre d’exploitants est passé de 148 à 92 entre 2008 et 2010 et le nombre de pieds de raphia saignés est passé de 15 452 à 8 832 durant la même période. Au total, l’exploitation du raphia dans le Hlanzoun s’inscrit dans un environnement défavorable par rapport aux exigences de développement durable d’une filière de PFNL. Mais les divers acteurs sont à présent conscients de la nécessité d’agir pour une meilleure réglementation de l’accès et de l’exploitation.
The commercial use of non woody forest products is a crucial issue in the international debate on the sustainable management of forests. These products are supposed to contribute to conservation by improving local populations’ livelihood and their involvement in forest management. This study lies within the scope of two South-South Cooperation projects (PSC 22P07 and PSC 03T08) implemented by the CEBEDES NGO with the financial support of the Kingdom of the Netherlands. It aims at analyzing the socioeconomic and environmental sustainability of the raffia stands management in the swamp forest "Hlanzoun ". This small forest is located in one of Benin southern Wetlands in the municipality of Zogbodomey.The methodology to assess raffia socioeconomic performances relies on the estimation of the values added within the raffia value chains. Stakeholders at every segment of the value chains have been surveyed on the incomes obtained out of raffia. The methodology to assess the sustainability of the management relies on a simple indicator measuring the ratio of younger to elder palms. Palms in stands have been counted according to their age group. The survey confirms that raffia is a multi-purpose plant used for its leaves, fibers, sap and trunk. In villages at the borders of the Hlanzoun forest, harvesting the raffia sap on standing palms and processing it into alcohol are a major income generating activity. Alcohol is then marketed through a network of collectors, wholesalers and petty traders up to the consumers. The contribution of raffia to local and regional development was estimated by the total incomes generated at 192.429.633 F CFA. All stakeholders earn positive and significant incomes in spite of the low level of technology and skills, but traders receive a large share of the wealth produced. As regard to governance, "free" access only concerns residents and efforts are made to control the access of non-residents. One notes a deficit of legitimated authorities, rules and procedures for a sustainable use: Restrictions on the harvest of immature palms are not anymore enforced and it endangers the renewal capacity of the resource. But at the same time, the number of operators seems to be decreasing (from 148 to 92 between 2008 and 2010, whereas the number of harvested raffia palms decreased from 15,452 to 8,832 during the same period). A self-regulation might occur, due to the fact that a livelihood of local people relies on a diversity of income generating activities. In total, the operation of Raffia in Hlazoun is in an unfavorable environment with the requirements of sustainable development in a sector of NTFF. But the various actors are now aware of the need for action to better regulate access and operation.
Bénin

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.5556
http://journals.openedition.org/etudescaribeennes/5556

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Cross-species analyses of plant functional traits have shed light on factors contributing to differences in performance and distribution, but to date most studies have focused on either leaves or stems. We extend these tissue-specific analyses of functional strategy towards a whole-plant approach by integrating data on functional traits for 13 448 leaves and wood tissues from 4672 trees representing 668 species of Neotropical trees. Strong correlations amongst traits previously defined as the leaf economics spectrum reflect a tradeoff between investments in productive leaves with rapid turnover vs. costly physical leaf structure with a long revenue stream. A second axis of variation, the 'stem economics spectrum', defines a similar tradeoff at the stem level: dense wood vs. high wood water content and thick bark. Most importantly, these two axes are orthogonal, suggesting that tradeoffs operate independently at the leaf and at the stem levels. By simplifying the multivariate ecological strategies of tropical trees into positions along these two spectra, our results provide a basis to improve global vegetation models predicting responses of tropical forests to global change.
ISSN: 1461-023X

hal-00594040
https://hal.archives-ouvertes.fr/hal-00594040

Éditeur(s) : Université de Bretagne Occidentale
Résumé : The negative impact of the man on the environment unquestionably increases. The coastal environment as a whole is the maritime environment which is the most exposed to man-made eutrophication. For instance, nitrate loads to coastal waters off Brittany (France) have increased 10 times (from 3 to s 30mg L-1NO3) during the four last decades. Eutrophication of this coastal zone is now a recurrent problem, more and more worrying. This eutrophication exhibits two main forms : " green tides ", which are caused by local proliferations and stranding of green macro-algae (particularly the Ulva species) in nitrogen-enriched areas ; phytoplanktonic blooms, which are responsible for coloured water events, toxic species can be present (Pseudo-Nitzschia, Alexandrium, Dinophysis), and induce banning of shellfish consumption. The objectives of this study are to assess the respective role of various rivers (especially the Loire and the Vilaine) in the eutrophication of the Brittany shelf ecosystem and test the impact of nitrogen enrichment in the triggering of Pseudo-Nitzchia toxicity. For these purposes, a coupled hydrodynamical/ biogeochemical 3D model has been developed and validated against past measured time-series and satellite images. After a brief analysis of primary production over the Brittany shelf under different conditions, we show a description of the real time adaptation of this model. Daily results are currently presented in real time on www.previmer.org web site. The inability of the model to correctly simulate near shore phytoplankton is worsened in this model by the fact that the turbidity field used is a climatological one, made by satellite images averaged on a decadal basis. First, near shore pixels of satellite images are scarcely reliable, secondly a climatological mean cannot represent the sudden bursts or drops of the real turbidity, highly dependent on the actual sea-state : this can explain also why the model at this moment fails to reproduce a sudden bloom occurring in a short period of sunny and calm weather. The simulated Pseudo-Nitzschia biomass and induced risk of toxicity in the water column cannot really be validated offshore, because monitoring measurements are available only near the coast, and deal only with toxicity in benthic filter feeders. To get temporarily rid of that problem, an interesting improvement would be to add to the operational model the bio-accumulation of toxin in the shellfishes : simulated concentrations in shellfish fresh would become directly comparable with usual measurements of the monitoring networks. Our model points out the important impact of Loire river loads on the primary production on the western and southern Brittany. This result is crucial for administrations in charge of reducing the terrestrial loadings responsible for eutrophication, because it can delay reduction programs on small tributaries until the main input from the Loire has been significantly reduced. A question arises, about the reliability of the haline stratification in the model, because the horizontal extent of the Loire plume will be enhanced by a stronger stratification.
L'eutrophisation des milieux marins côtiers, de plus en plus importante, représente un des impacts majeurs des activités humaines sur l'environnement. Les phénomènes d'eutrophisation sont en constante augmentation ; ces dernières décennies ont vu le nombre de sites touchés augmenter de par le monde. La bande côtière bretonne est particulièrement concernée par ce phénomène. L'eutrophisation s'y manifeste de deux façons : "Des phénomènes de marée vertes, très localisées, qui sont provoqués par la croissance excessive et l'échouage de macro-algues du genre Ulva dans ces zones riches en azote ; Des blooms de phytoplancton à l'origine des phénomènes d'eaux colorées, qui peuvent aussi provoquer des interdictions de consommation de coquillages lorsque les espèces mises en jeu sont toxiques (Pseudo-Nitzschia, Alexandrium, Dinophysis). L'objectif de ce travail est multiple : il vise à mettre en évidence et à comprendre l'impact et le rôle des apports en nutriments sur la production primaire et l'eutrophisation des milieux côtiers. Ce travail a aussi pour ambition l'identification et la compréhension des causes des phénomènes d'eutrophisation et permettre ainsi d'apporter des solutions ou des pistes d'amélioration. En n, il a aussi un objectif de prévision à court terme de l'état biologique sur la zone. Pour atteindre ces objectifs, un modèle en temps réel a été mis en oeuvre. Les résultats de simulations numériques et de mesures satellitaires sont présentés sur internet : www.previmer.org. L'outil principal de ce travail est un modèle couplé physique/biogéochimie. La partie hydrodynamique est fournie par le code Mars3D (3D hydrodynamical Model for Application at Regional Scale) développé à IFREMER. Au code hydrodynamique Mars3D est couplé le modèle des cycles de l'azote, du phosphore et du silicium d'IFREMER. Le modèle couplé permet de simuler en 3 dimensions et de manière dynamique les courants, le brassage horizontal et vertical, les champs de température et de salinité, mais aussi les principaux cycles de nutriments, reproduisant ainsi les conditions déterminantes de la production primaire. La croissance des algues est modélisée, et nous permet de voir l'influence des panaches de dilution des principales rivières bretonnes sur leur croissance. Les diffcultés du modèle à correctement simuler les concentrations en phytoplancton près des zones côtières, sont probablement dues à l'utilisation d'une climatologie de concentration en matière en suspension fondée sur des données satellitaires. Tout d'abord, les pixels côtiers des images satellitaires sont entachés d'erreurs, ensuite une climatologie n'est pas capable de représenter les apports soudains des fleuves lors des crues. Cela peut expliquer l'incapacité du modèle a représenter certains blooms liés à des périodes ensoleilées et calmes. A ce modèle de base nous avons ajouté un genre spécifique de phytoplancton : le genre Pseudo-Nitzschia. Certaines espèces de Pseudo-Nitzschia sont réputées toxiques. En effet, ce phytoplancton a la capacité de synthétiser une toxine : l'acide domoïque. Cette toxine est responsable du syndrome ASP (Amnesic Shellfish Poisoning). Le modèle reproduit globalement les mêmes zones de toxicité que les mesures du REPHY, et donne des résultats encourageants. L'étude montre que la Loire influence une large partie de la bande côtière bretonne ; son panache remonte jusqu'au nord de la mer d'Iroise, et contribue pour une grande part à l'enrichissement du sud et de l'ouest de la Bretagne. Le traçage de l'azote en provenance de la Loire au sein des cycles biogéochimiques nous a permis de quantifier cet enrichissement.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00015/12603/9481.pdf
http://archimer.ifremer.fr/doc/00015/12603/

Éditeur(s) : HAL CCSD
Résumé : International audience
Background In life sciences, there is a growing need for new informatics tools designed to provide automated solutions in order to analyze big amounts of images obtained from high-throughput imaging systems. Among the most widely used assays in neurotoxicity, endocrinology and brain diseases, the neurite outgrowth assay is popular. New method Cell-to-cell quantification of the main morphological features of neurite outgrowth assays remains very challenging. Here, we provide a new pipeline developed on Fiji software for analysis of series of two-dimensional images. It allows the automated analysis of most of these features. Results We tested the accuracy and usefulness of the software by confirming the effects of estradiol and hypoxia on in vitro neuronal differentiation, previously published by different authors with manual analysis methods. With this new method, we highlighted original interesting data. Comparison with existing method(s) The innovation brought by this plugin lies in the fact that it can process multiple images at the same time, in order to obtain: the number of nuclei, the number of neurites, the length of neurites, the number of neurites junctions, the number of neurites branches, the length of each branch, the position of the branch in the image, the angle of each branch, but also the area of each cell and the number of neurites per cell. Conclusions This plugin is easy to use, highly sensitive, and allows the experimenter to acquire ready-to-use data coming from a vast amount of images. © 2016 Elsevier B.V.
Journal of Neuroscience Methods

hal-01367152
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01367152
DOI : 10.1016/j.jneumeth.2016.07.011
PUBMED : 27450924

Éditeur(s) : HAL CCSD
Résumé : Due to their phylogenetic position outside from Bilateria, cnidarians and ctenophores are key phyla to understanding the origin and early evolution of molecular mechanisms, cell types, or body plan features at the level of Metazoa. Unlike other non-bilaterian phyla (sponges and placozoans), they possess neurons and muscle cells. The first part of my work relates to the problem of the origin of the metazoan nervous system. Recent studies have suggested a dual origin for nerve cells, with ctenophore neurons having emerged independently from those of cnidarians and bilaterians. This hypothesis relies on phylogenomic analyses supporting ctenophores as sister-group to all other metazoans, and on the purported absence in ctenophores of almost all well-known neuro-transmission systems, including the cholinergic system. Refuting this claim, I present substantial evidence in favour of acetylcholine (Ach) being used in the ctenophore Pleurobrachia pileus as an extra-cellular messenger, including within the nervous system. This conclusion arises from the conjunction of multiple approaches at the molecular scale (orthology analyses, Ach immuno-localisation, gene in situ hybridisation), at the cellular scale (calcium imaging on muscle cells exposed to Ach) and at the organism scale (pharmacological treatments with an Ach analogue and Ach antagonists). In the second part of my thesis, I address the conservation of molecular mechanisms involved in the control of cellular proliferation. Notably, the Hippo pathway is known for its role in bilaterians in the negative control of cellular proliferation. I show that components of this pathway are conserved in Pleurobrachia pileus and in Clytia hemisphaerica and that the nuclear vs. cytoplasmic localisation of the transcriptional co-factor Yorkie is correlated to the extent of proliferation within C. hemisphaerica tissues. Finally, RNAseq differential gene expression analyses along a cellular conveyor belt of the C. hemisphaerica medusa suggests a tendency for conservation of function among a set of genes whose mammalian orthologues have documented roles in the arrest of cellular proliferation.
Les Cnidaires et les Cténaires sont deux embranchements extérieurs aux Bilatériens qui, de par leur position phylogénétique, constituent des modèles d'étude cruciaux pour comprendre l'origine et l'évolution de mécanismes moléculaires ou encore de types cellulaires à grande échelle chez les Métazoaires. Ils sont les deux seuls embranchements non-Bilatériens à posséder des cellules nerveuses ainsi que des cellules musculaires. La première partie de mon travail de thèse s'inscrit dans le contexte de la compréhension de l'origine du système nerveux des Métazoaires. Des études récentes suggèrent une origine double du système nerveux ; ainsi celui des Cténaires aurait été acquis de manière convergente par rapport à celui des Cnidaires et des Bilatériens. Cela repose sur des données récentes de phylogénomique proposant les Cténaires en tant que groupe-frère de tous les autres Métazoaires et sur l'absence supposée chez les Cténaires de quasiment tous les systèmes de neurotransmission connus y compris le système cholinergique. A l'encontre de ces hypothèses, j'ai pu mettre en évidence l'existence d'un système cholinergique chez le Cténaire Pleurobrachia pileus ainsi que son étroite association avec le système nerveux. Cette conclusion repose sur une multiplicité d'approches à l'échelle moléculaire (analyses d'orthologie, immunolocalisation, hybridations in situ), cellulaire (imagerie calcique) et de l'organisme (approche pharmacologique). Dans la seconde partie de ma thèse, j'aborde la question de la conservation des mécanismes moléculaires impliqués dans le contrôle de la prolifération cellulaire à l'échelle des Métazoaires. J'ai pu mettre en évidence la conservation des acteurs.
https://tel.archives-ouvertes.fr/tel-01633223

NNT : 2015PA066629
tel-01633223
https://tel.archives-ouvertes.fr/tel-01633223
https://tel.archives-ouvertes.fr/tel-01633223v2/document
https://tel.archives-ouvertes.fr/tel-01633223/file/2015PA066629.pdf

Éditeur(s) : HAL CCSD
Résumé : Time-series bathymetric data acquired between 1991 and 2011 have been used to evaluate the recent morphological evolution of the Nice upper continental slope (SE France, Ligurian Sea). Small-scale landslides lead to a retrogressive evolution of the continental shelf/upper slope transition but their frequency, size and impact are not well known. Mapping was undertaken to identify the morphology of landslide scarps and the location of the shelfbreak. Map comparisons were performed using ArcGIS “raster calculator”. Sediment remobilization on the upper slope (up to depths of 200 m) is fast and significant; landslide scars with volumes greater than 25,000 m3 can appear with a frequency less than 8 years. Shelfbreak migration toward the coastline can reach rates of 60 m over 7–8 years where the continental shelf is over 200 m wide. Furthermore, this quantitative analysis highlights alternations between periods of strongly erosive events and sedimentation periods. On the upper slope, eroded volumes can be multiplied by 10 during periods of enhanced landslide patterns (1999–2006). Such cycle-like landslide activity raises the issue of the triggering processes. On the Nice continental slope thick poorly consolidated beds rapidly deposited on a steep slope, earthquakes and rainfall leading to fresh water circulation below the shelf were identified as potential triggers. Our 4D bathymetric study suggests that over the last 20 years the greatest impacting factor may be freshwater outflows.
Engineering Geology for Society and Territory - Volume 4

hal-01218436
https://hal.archives-ouvertes.fr/hal-01218436
DOI : 10.1007/978-3-319-08660-6_42

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé :  
Cross-species analyses of plant functional traits have shed light on factors contributing to differences in performance and distribution, but to date most studies have focused on either leaves or stems. We extend these tissue-specific analyses of functional strategy towards a whole-plant approach by integrating data on functional traits for 13 448 leaves and wood tissues from 4672 trees representing 668 species of Neotropical trees. Strong correlations amongst traits previously defined as the leaf economics spectrum reflect a tradeoff between investments in productive leaves with rapid turnover vs. costly physical leaf structure with a long revenue stream. A second axis of variation, the 'stem economics spectrum', defines a similar tradeoff at the stem level: dense wood vs. high wood water content and thick bark. Most importantly, these two axes are orthogonal, suggesting that tradeoffs operate independently at the leaf and at the stem levels. By simplifying the multivariate ecological strategies of tropical trees into positions along these two spectra, our results provide a basis to improve global vegetation models predicting responses of tropical forests to global change.
Ecology Letters

hal-01032142
https://hal.archives-ouvertes.fr/hal-01032142
DOI : 10.1111/j.1461-0248.2010.01517.x