Éditeur(s) : Université des Antilles et de la Guyane
Résumé : The need for an integrated approach to fisheries is now widely affirmed, including the FAO, in particular in the context of tropical artisanal fisheries. These small-scale fisheries, often multispecies are very important in terms of production, employment and food security. However these fisheries and the exploited resources are often characterized by a lack of data making difficult their management within an ecosystem approach, and by the ecological and economic system complexities including trophic and technological interactions. This thesis aims to contribute to the development of bioeconomic tools for small tropical fisheries in a sustainable management perspective based on the ecosystem approach. In this perspective, the French Guiana coastal fishery constitutes an interesting case study. The thesis proposes multi-criteria evaluations, complex bioeconomic models and viable management scenarios for this fishery. At first, multivariate statistical analysis suggests a satisfactory overall status of the fishery in terms of sustainability. However, some performance differences are noted within the fishery, particularly at border areas. Also, management improvements are proposed. Then, through bioeconomic modeling, projections of different fishing scenarios show that, in the long-term, the current exploitation level may not be consistent with the future increase of local demand and a loss of biodiversity may occur. A scenario called "co-viability" reconciling ecological, economic and social objectives, with a high probability of achievement is exhibited. Finally, the comparison of optimal behavior in cooperative and non-cooperative conditions, confirms that harvest levels are greater when actors do not cooperate. Furthermore, it is shown that the state of the ecosystem depends on the fishing strategies and the type of interaction between species. Beyond the diagnosis made for the case study, the method is promising in the context of small tropical fisheries, while the co-viability approach allows finding the exploitation conditions under which ecological and socio-economic sustainability are meet, what the conventional fisheries management generally do not allow.
La nécessité d’une approche intégrée des pêches est actuellement largement affirmée, notamment par la FAO, en particulier dans le contexte des pêcheries artisanales tropicales. Ces pêcheries à petites échelles, souvent multi-spécifiques sont très importantes en termes d’emploi et de production, y compris pour la sécurité alimentaire. Néanmoins ces pêcheries et la biodiversité exploitées sont souvent marquées, d’une part, par le manque de données rendant difficile leur gestion dans le cadre d’une approche écosystémique, d’autre part, par la complexité des systèmes écologiques et économiques sous-jacents incluant interactions trophiques et techniques. Cette thèse contribue à la mise au point d’outils bioéconomiques adaptés aux petites pêcheries tropicales dans la perspective d’une gestion durable des pêches fondée sur l’approche écosystémique. Dans cette perspective, la pêcherie côtière en Guyane Française constitue un cas d’étude particulièrement fécond. La thèse propose ainsi des évaluations multi-critères, des modèles bioéconomiques complexes et des scénarios de gestion viable pour cette pêcherie. Dans un premier temps l’analyse statistique multivariée suggère un statut global satisfaisant de la pêcherie en termes de durabilité. Cependant des différences de performance sont notées au sein de la pêcherie, notamment au niveau des zones frontalières. Aussi des améliorations dans le mode de gestion sont proposées. Ensuite, à travers la modélisation bioéconomique, les projections des différents scénarios de pêche montrent qu’à long terme le niveau d’exploitation actuel peut ne pas être en adéquation avec la future augmentation de la demande locale et qu’une perte de biodiversité peut avoir lieu. Un scenario dit de "co-viabilité" conciliant des objectifs à la fois écologique, économique et social, avec une probabilité de réalisation satisfaisante, est mis en exergue. Enfin, la comparaison des comportements optimaux en situation coopératif et non coopératif, montre dans quelle mesure la viabilité est favorisée quand les acteurs coopèrent. Au-delà du diagnostic apporté pour le cas d’étude, la méthode utilisée s’avère prometteuse dans le contexte des petites pêcheries tropicales, tandis que l’approche de co-viabilité permet de trouver les modalités d’exploitation dans le cadre de compromis entre durabilité écologique et socio-économique, ce que les principes de gestion halieutiques traditionnels ne permettent généralement pas.

Droits : 2013 Université des Antilles et de la Guyane
http://archimer.ifremer.fr/doc/00144/25492/23646.pdf
http://archimer.ifremer.fr/doc/00144/25492/

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : While oceanic circulation in the Gulf of Lion (GoL) has often been studied in calm weather or with northerly winds (Tramontane or Mistral) through observations and numerical circulation models, few studies have focused on southeasterly storm events. Yet, correct representation of the circulation during storms is crucial if the suspension of sediments is to be correctly modelled throughout the Gulf. The purpose of this paper is to describe the hydrodynamics in the Gulf of Aigues-Mortes (NW of the GoL) during the storm of 18 February 2007 by using a set of data from an ADCP station placed at a depth of 65 m on the sea bed off the coast at Sète, supplemented by the ocean circulation model SYMPHONIE. This storm was characterized by a moderate south-easterly wind (15 m . s−1) and waves of up to 5 m of significant height at its apex. At the ADCP, strong currents of up to 0.8 m . s−1 near the surface and 0.5 m . s−1 near the bottom were recorded, parallel to the coast, flowing towards the south-west. The simulated currents were widely underestimated, even taking the effect of waves into account in the model. It was suspected that the representation of the wind in the atmospheric model was an underestimation. A new simulation was therefore run with an arbitrarily chosen stronger wind and its results were in much better agreement with the measurements. A simplified theoretical analysis successfully isolated the wind-induced processes, responsible for the strong currents measured during the apex and the strong vertical shear that occurred at the beginning of the storm. These processes were: 1/ the barotropic geostrophic current induced by a wind parallel to the coast and 2/ the Ekman spiral. The duration of the storm (about 36 h at the apex) explains the continuous increase of the current as predicted by the theory. The frictionally induced Ekman transport explains the current shear in the surface layer in the rising stage of the storm, and the addition of high waves and strong wind at the apex is more in favour of strong vertical mixing in the surface layer.
ISSN: 1631-0713

hal-00908200
https://hal.archives-ouvertes.fr/hal-00908200
DOI : 10.1016/j.crte.2013.07.001

Éditeur(s) : HAL CCSD Editions Paralia CFL
Résumé : Des techniques d'optimisation de formes sont utilisées dans des problèmes du Génie Côtier pour la protection des plages. En collaboration avec le bureau d'étude Bas-Rhône Languedoc ingénierie, un projet d'aménagement concret de la plage du Lido de Sète, utilisant des ouvrages immergés en géotextile, a été étudié. Des solutions optimales, visant à réduire la mise en suspension des sédiments, pour les structures de défenses ont été obtenues à partir d'un modèle hydrodynamique de propagation de houle. Une étude complémentaire à partir d'un modèle de circulation et des travaux expérimentaux en canal à houle permettent ensuite de valider les résultats optimaux numériques obtenus. Shape optimization techniques, focusing on coastal structures design, are used to solve coastal engineering problem. In collaboration with the Bas-Rhône Languedoc engineering Company, a actual development plan concerning the beach of the Lido of Sète has been studied. Optimal solutions, aimed at reducing sediments suspended, for defense structures have been obtained with a hydrodynamic water wave model. An additional study using a circulation model and experimental works in flume tend to validate optimal numerical results.
ISSN: 1760-8716

hal-00854031
https://hal.archives-ouvertes.fr/hal-00854031
DOI : 10.5150/jngcgc.2008.025-I

Éditeur(s) : HAL CCSD
Résumé : International audience
The identification and economic valuation of ecosystem services (ES) are becoming important components of coral reef management. In many contexts, protection of human assets against coastal floods is one of the most important ES provided by coral reefs. The methods utilized to characterize this ES should be able to accommodate situations with low data availability, without sacrificing robustness. In this paper, we suggest such an approach that utilizes expert opinion and does not require copious amounts of data. Our primary objective is to find a balance between simple and complex models that can be used in a data scarce environment, to produce an economic valuation of the coral reef ES of protection against coastal floods. The approach has three steps: (i) identify geographic zones and assets at risk, (ii) identify the contributing role of coral reefs in the protection of coasts and, (iii) value the annual repair costs of assets through the avoided damage cost approach. The proposed method seems appropriate for advocacy with policy makers, but appears to be less effective for small scale approaches, such as those required for Payment for ES negotiations or marine spatial planning.
Ecosystem Services

hal-01359394
https://hal-univ-perp.archives-ouvertes.fr/hal-01359394
DOI : 10.1016/j.ecoser.2016.07.005

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Coral reef resource systems are complex adaptive social-ecological systems providing vital and valuableecosystem services for human societies such as food provision, coastal protection and recreational activities.Their sustainability is questioned in many places around the world as they experience combined effects ofmultiple chronic anthropogenic and natural drivers at local to global scales. From a management perspective,there is a crucial need to understand how the impact of these drivers cascade through the social-ecologicalsystem components. This study develops a transdisciplinary and participatory approach to investigating thesocial-ecological dynamics of a Polynesian coral reef coastal system. A preliminary conceptual model using theDriver-Pressure-State-Impact (DPSI) framework is first being built through participatory modeling workshops.Then, pressure-state relationships are assessed with the help of empirical datasets as a first step towards thevalidation of the DPSI model. Results shows striking social-ecological interactions with different patterns in thelagoon and in the fore reef. Local management should be: (1) less resource-focused to account more specificallyto the existing typology of actors; (2) more spatially-explicit to better distinguish management objectives andactions for the lagoon and the fore reef sub-systems; and (3) more coordinated with terrestrial agencies for acoherent land-sea connection and integration that would both (i) account for existing land-sea interactions and(ii) better reflect the Polynesian cultural heritage that considers nature from ridge to reef as a whole. Suchconceptual models of social-ecological systems are a useful tool to build exploratory scenarios to ultimatelysupport planning decision-making processes.
ISSN: 0308-597X

hal-01491968
https://hal-univ-perp.archives-ouvertes.fr/hal-01491968
DOI : 10.1016/j.marpol.2017.01.014

Éditeur(s) : HAL CCSD Société géologique de France
Résumé : The Maguelone shore extends along the northern coast of the Gulf of Lions margin, West of the Rhone delta and East of some high gradient coastal streams that have been providing most of the elastic sediments to the Gulf of Lions margin since the early Miocene. This 10 km wide area comprises an onshore small coastal watershed (15 km long) in low-lying carbonate hills, kilometer wide marshes, sandy beach and shoreface featuring local low sedimentation. Deposit architecture in such a coastal zone records dynamics of incised valley fill under the influence of rivers and wave/current hydrodynamics in a microtidal environment during an eustatic cycle.;A detailed analysis of about 250 km of very high resolution seismic profiles, tens of cores and outcrops data revealed the evolution of the Maguelone coastal system from Late-Quaternary to present-day. It highlighted also dominant denudation processes in the upstream catchments associated to the formation of incised valley seaward during Quaternary. Combination of this inherited morphology together with hydrodynamics controlled the lagoonal environment evolution since the last transgression. In particular, the Maguelone shore is characterized by the formation of built-over-rias lagoonal systems and records an evolution from partially protected lagoon to isolated lagoon environment. These two stages of lagoon evolution correspond to distinct deposit environments. Correlation of fauna contents with deposit geometry improves lagoonal environment models.
EISSN: 1777-5817

hal-00486370
https://hal.archives-ouvertes.fr/hal-00486370
DOI : 10.2113/gssgfbull.181.2.211

Éditeur(s) : HAL CCSD
Résumé : Report
The Canadian coastline is the longest of any country in the world, and is at risk from tsunamis generated in three oceans. The current state of knowledge precludes a complete probabilistic tsunami hazard assessment, which would require quantification of a wide range of possible scenarios for each tsunami source, coupled with modelling that incorporates fine-resolution bathymetry and onland topography to adequately assess potential runup at the coast. This preliminary assessment presents a first attempt to quantify the tsunami hazard on the Canadian Pacific, Atlantic and Arctic coastlines from local and far-field, earthquake and large landslide sources. For each source considered, we calculate the probability that tsunami runup at the coast will exceed 1.5 m (threshold for potential damage) and 3 m (significant damage potential), in a 50-year period. For each coastal region, we then combine the relative hazard from each source to calculate the overall probability that the coastline in question will experience tsunami runup exceeding 1.5 m (and 3 m) within a 50-year period, from any geological source. We also consider the maximum runup levels expected to occur within time periods of 100, 500, 1000, and 2500 years.
https://hal.archives-ouvertes.fr/hal-00856677

hal-00856677
https://hal.archives-ouvertes.fr/hal-00856677
DOI : 10.4095/292067

Éditeur(s) : HAL CCSD Université des Antilles
Résumé : International audience
In this study, we propose to analyze the limits of mass tourism in the French Antilles, specifically the decline of tourism, economic limits, and ecological degradation). The recognition of these limits is overdue, and signals a need to define another model for tourism development.The popular coastal sector in the south of Martinique has been subject new regulations to protect marine resources. These regulations require the development of new practices and a greater level of awareness for tourists, for example, around coral reefs and mangroves. Ecotourism programs aim to demonstrate to visitors the forests rich natural resources and biodiversity in general. It also features the inclusion of small rural businesses that benefit from additional sources of revenue as a result of ecotourism.The situation in the French Antilles is complex: Urbanization is fraught with serious consequences for the coastline. Tourism products currently being marketed on the island are not competitive (particularly against the political dynamics of the neighbouring island of Dominica). Ecotourism and sustainable tourism are just beginning to develop in such destinations, where tourism has been declining in the last ten years. The situation of the French Antilles is paradoxical in a region that generally has a very favourable tourism. Assessing these limits through the scope of ecotourism helps to highlight the causes of these difficulties and to adapting to new tourism practices.
En el contexto de este estudio, nos proponemos analizar los límites del turismo de masas en las Antillas Francesas (depreciación del turismo, las limitaciones económicas, ecológicas y las molestias). Este reconocimiento de esos límites está en el origen de la conciencia tardía de la necesidad de definir otro modelo de desarrollo turístico.En el sector costero de la más popular, como en el sur de Martinica, se pone en la normativa nuevo lugar para proteger los recursos marinos. Esto requiere el desarrollo de nuevas prácticas y la sensibilización de los turistas, por ejemplo, alrededor de los arrecifes de coral y los manglares.Programas en torno al ecoturismo también tienen como objetivo dar al visitante la riqueza de los recursos forestales y la biodiversidad en general. También incluye las pequeñas empresas rurales que reciben los nuevos ingresos a través del turismo.Pero la situación es compleja en las Antillas francesas: la urbanización está llena de importantes consecuencias para la costa. Productos turísticos que se comercializan actualmente no son competitivos (en particular, contra la dinámica política de la cercana isla de Dominica). Ecoturismo y desarrollo sostenible están empezando a desarrollar en este destino turístico, donde el turismo está en problemas en los últimos diez años.Esta situación es bastante paradójico en un turismo regional muy favorable. Sin lugar a dudas, pensando en el ecoturismo contribuye a identificar los destinos de estos retrasos y dificultades para adaptarse a nuevas prácticas de turismo.
Dans le cadre de cette étude, l’accent est mis sur les limites du tourisme de masse dans les Antilles françaises (dépréciation du tourisme, les contraintes économiques et les nuisances écologiques). La reconnaissance de ces limites est à l'origine de la prise de conscience tardive de la nécessité de définir un autre modèle de développement touristique.Dans le sud de la Martinique, le secteur le plus populaire du littoral, de nouvelles règlementations sont mises en place pour protéger les ressources marines. Cela nécessite le développement de nouvelles pratiques et de sensibilisation des touristes notamment autour des récifs coralliens et les mangroves. Les programmes autour de l'écotourisme visent également à montrer aux visiteurs la richesse des ressources forestières et de la biodiversité en général. Il comprend également les petites entreprises rurales qui reçoivent de nouveaux revenus grâce au tourisme.La situation est complexe dans les Antilles françaises: l'urbanisation est lourde de conséquences importantes sur la côte. Les produits touristiques commercialisés actuellement ne sont pas compétitifs (notamment contre la dynamique politique de l'île voisine de la Dominique). L'écotourisme et le tourisme durable commencent tout juste à se développer dans ces destinations où le tourisme classique est en difficulté depuis une dizaine d’années ; situation assez paradoxale au regard du dynamisme de ce secteur d’activité dans la région.
ISSN: 1779-0980

hal-01624756
https://hal.archives-ouvertes.fr/hal-01624756
DOI : 10.4000/etudescaribeennes.5262

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The effects of biodiversity on the transmission of infectious diseases now stand as a cornerstone of many public health policies. The upper Amazonia and Guyana shield are hot-spots of biodiversity that offer genuine opportunities to explore the relationship between the risk of transmission of Chagas disease and the diversity of its triatomine vectors. Over 730 triato-mines were light-trapped in four geomorphological landscapes shaping French-Guiana, and we determined their taxonomic status and infection by Trypanosoma cruzi. We used a model selection approach to unravel the spatial and temporal variations in species abundance , diversity and infection. The vector community in French-Guiana is typically made of one key species (Panstrongylus geniculatus) that is more abundant than three secondary species combined (Rhodnius pictipes, Panstrongylus lignarius and Eratyrus mucronatus), and four other species that complete the assemblage. Although the overall abundance of adult triatomines does not vary across French-Guiana, their diversity increases along a coastal-inland gradient. These variations unravelled a non-monotonic relationship between vector biodiversity and the risk of transmission of Chagas disease, so that intermediate biodiversity levels are associated with the lowest risks. We also observed biannual variations in triatomine abundance, representing the first report of a biannual pattern in the risk of Cha-gas disease transmission. Those variations were highly and negatively correlated with the average monthly rainfall. We discuss the implications of these patterns for the transmission of T. cruzi by assemblages of triatomine species, and for the dual challenge of controlling Amazonian vector communities that are made of both highly diverse and mostly intrusive species.
ISSN: 1935-2727

Droits : http://creativecommons.org/licenses/by/
hal-01298091
https://hal-univ-perp.archives-ouvertes.fr/hal-01298091
https://hal-univ-perp.archives-ouvertes.fr/hal-01298091/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01298091/file/journal.pntd.0004427.PDF
DOI : 10.1371/journal.pntd.0004427

Éditeur(s) : Copernicus Gesellschaft Mbh
Résumé : Deep-sea bivalves found at hydrothermal vents, cold seeps and organic falls are sustained by chemosynthetic bacteria which ensure part or all of their carbon nutrition. These symbioses are of prime importance for the functioning of the ecosystems. Similar symbioses occur in other bivalve species living in shallow and coastal reduced habitats worldwide. In recent years, several deep-sea species have been investigated from continental margins around Europe, West Africa, East America, the Gulf of Mexico, and from hydrothermal vents on the Mid-Atlantic Ridge. In parallel, numerous more easily accessible shallow marine species were studied. We here provide a summary of the current knowledge available on chemosymbiotic bivalves in the area ranging west-to-east from the Gulf of Mexico to Marmara Sea, and north-to-south from the Arctic to the Gulf of Guinea. Characteristics of symbioses in 51 species from the area are summarized for each of the five bivalve families documented to harbor chemosynthetic symbionts (Mytilidae, Vesicomyidae, Solemyidae, Thyasiridae and Lucinidae), and compared among families with special emphasis on ecology, life cycle, and connectivity. Chemosynthetic symbioses are a major adaptation to ecosystems and habitats exposed to reducing conditions, yet relatively little is known regarding their diversity and functioning apart from a few "model species" on which effort has focused over the last 30 yr. In the context of increasing concern about biodiversity and ecosystems, and increasing anthropogenic pressure on Oceans, we advocate for a better assessment of bivalve symbioses diversity in order to evaluate the capacities of these remarkable ecological and evolutionary units to withstand environmental change
Biogeosciences (1726-4170) (Copernicus Gesellschaft Mbh), 2013 , Vol. 10 , N. 5 , P. 3241-3267

Droits : Author(s) 2012. CC Attribution 3.0 License.
http://archimer.ifremer.fr/doc/00133/24417/22431.pdf
DOI:10.5194/bg-10-3241-2013
http://archimer.ifremer.fr/doc/00133/24417/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We have discovered in a marine core, located 20 km east of the Coastal Range of Taiwan at the top of a 1200 m deep submarine high, sheltered from rivers discharges and gravitational flows, a 23 cm-thick anomalous sequence topped with broken bivalves and wood fragments. Based on radiocarbon dating, we distinguish five sub-events within ∼ 100 yrs, about 3000 years ago. The oldest four sub-events are interpreted as the record of local submarine landslides, likely triggered by clustered earthquakes that are common in this tectonically active area. The last event including shells and wood has a different origin. Despite the high level of climatic and tectonic recent activity, no comparable event has been observed at the same site since that time, making it unique during the last 3.75 ka. Hydrodynamical modeling stimulated with a set of submarine landslide-triggered tsunami sources and combined with the regional oceanic circulation dominated by the Kuroshio Current, allow us to better constrain the transport paths of the suspended material, the expected run-up at the coast, and ultimately the trigger and source that best fit our observations. The Kuroshio Current appears as a strong constraint that generally prevents cross-shore transport of suspended material even during a major tsunami. Since the largest aerial debris flow observed along the east coast of Taiwan during the last 4 ka was synchronous with the marine deposit, our preferred scenario starts with the occurrence of four distinct large earthquakes within less than a century, triggering both submarine and aerial landslides in the study area. Then, a giant typhoon reworked the nearshore material as well as the slided material stored upstream resulting in a debris flow. It deeply modified the surface current, allowing the wood debris and shells to fastly reach the core site.
ISSN: 0040-1951

hal-01467640
https://hal.archives-ouvertes.fr/hal-01467640
DOI : 10.1016/j.tecto.2015.11.001

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : International audience
We develop and implement a new method to take into account the impact of waves into the 3-D circulation model SYMPHONIE (Marsaleix et al., 2008, 2009a), following the simplified equations of Bennis et al. (2011) which use glm2z-RANS theory (Ardhuin et al., 2008b). These adiabatic equations are completed by additional parameterizations of wave breaking, bottom friction and wave-enhanced vertical mixing, making the forcing valid from the surf zone through to the open ocean. The wave forcing is performed by wave generation and propagation models WAVEWATCH III® (Tolman, 2008, 2009; Ardhuin et al., 2010) and SWAN (Booij et al., 1999). The model is tested and compared with other models for a plane beach test case, previously tested by Haas and Warner (2009) and Uchiyama et al. (2010). A comparison is also made with the laboratory measurements of Haller et al. (2002) of a barred beach with channels. Results fit with previous simulations performed by other models and with available observational data. Finally, a realistic case of energetic waves travelling over a coast of the Gulf of Lion (in the northwest of the Mediterranean Sea) for which currents are available at different depths as well as an accurate bathymetric database of the 0-10 m depth range, is then simulated. A grid nesting approach is used to account for the different forcings acting at different spatial scales. The simulation coupling the effects of waves and currents is successful to reproduce the powerful northward littoral drift in the 0-15 m depth zone. More precisely, two distinct cases are identified: when waves have a normal angle of incidence with the coast, they are responsible for complex circulation cells and rip currents in the surf zone, and when they travel obliquely, they generate a northward littoral drift. These features are more complicated than in the test cases, due to the complex bathymetry and the consideration of wind and non-stationary processes. Wave impacts in the inner shelf are less visible since wind and regional circulation seem to be the predominant forcings. Besides, a discrepancy between model and observations is noted at that scale, possibly linked to an underestimation of the wind stress. Lastly, this three-dimensional method allows a good representation of vertical current profiles and permits to calculate the shear stress associated with wave and current. Future work will focus on the combination with a sediment transport model.
ISSN: 1812-0806

hal-00766548
https://hal.archives-ouvertes.fr/hal-00766548
https://hal.archives-ouvertes.fr/hal-00766548/document
https://hal.archives-ouvertes.fr/hal-00766548/file/os-8-657-2012.pdf
DOI : 10.5194/osd-8-2417-2011

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : French Polynesia started it's Fish Aggregating Device programme in June 1981 with the positioning of the first buoy offshore of the main island of Tahiti. Since then, 251 structures have been installed throughout the 5 archipelagoes of this French overseas territory. The shape and size of the devices have evolved 8 times over this period, however, a single model has not yet been adopted. Trials are currently underway using lighter structures similar to those found in the Indian Ocean. The anchoring lines have progressively been modified through better knowledge of material and product availability, as well as better understanding of environmental constraints. The programme is entirely financed by the territorial government and managed by the public sector. This ongoing technical assistance, aimed towards the local small-scale coastal fishery, is considered an important factor to maintaining this activity alive. Up until 1997, this economical support policy of outer island populations far from the metropolis central town, along with incidental fishing methods around FADs, have given mitigated results without nevertheless putting into cause this programme. The use of 'drifting handlines' retained at the surface by small indicator floats are one of the contributing factors to the degradation of the anchor lines. It is now commonly accepted that a new fishing strategy must be adopted so that professional coastal fishermen become more aware with regards to an expensive work tool due to local bathymetric conditions, so that fishing effort is increased through the development of better adapted fishing techniques, and finally so that community spirit rules over individualism.Original Abstract: Le programme d'ancrage de DCP en Polynesie francaise a vu le jour en juin 1981 avec l'implantation d'un premier dispositif au large des cotes de Tahiti. Depuis cette date, ce sont 251 structures qui ont ete installees dans les cinq archipels de ce pays d'outre-mer. La forme et la taille des bouees ont evolue huit fois sans etre definitivement arretees a un seul modele et des essais sur des structures legeres de type " Ocean Indien " sont en cours. Les lignes d'ancrage ont fait l'objet de modifications progressives en raison de meilleures connaissances des produits ainsi que des contraintes du milieu environnant. Ce programme est finance en totalite par le territoire de la Polynesie francaise et gere par le secteur public. Il s'adresse a la pecherie artisanale et cotiere qui considere depuis de nombreuses annees cette assistance technique comme un atout indispensable au maintien de son activite. La politique d'engagement de ce soutien economique jusqu'en 1997 aupres des populations d'iles et atolls tres eloignes de la capitale ainsi que l'incidence de la technique de peche la plus repandue autour des DCP ont abouti a des resultats mitiges sans pour autant remettre en cause ce programme. En effet, les lignes a main derivantes et retenues en surface par une petite bouee temoin sont un des principaux facteurs de degradation des lignes d'ancrage. Il est desormais reconnu par tous les intervenants qu'une nouvelle strategie doit etre deployee afin que les pecheurs cotiers professionnels soient mieux responsabilises face a un outil de travail onereux en raison de la bathymetrie environnante, pour que l'effort de peche soit accru par l'utilisation de techniques de peche mieux adaptees, et enfin que l'esprit communautaire prime sur l'individualisme.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15292/12649.pdf
http://archimer.ifremer.fr/doc/00042/15292/

Éditeur(s) : HAL CCSD Inter Research
Résumé : International audience
The main objective of the VULSACO (VULnerability of SAndy COasts to climate change and anthropic pressure) project was to investigate present day and potential future vulnerability of sandy coasts at the 2030 horizon, i.e. on a time scale related to climate variability. The method, based on a multidisciplinary approach bringing together geologists, geographers, physicists, social psychologists, engineers and stakeholders, was structured around 4 axes: field data analysis; numerical modelling; analysis of governance and stakeholder perceptions; and development of vulnerability indexes. This approach was designed to investigate vulnerability at a local scale and was applied to 4 contrasting beaches located in France: Sète Lido (Mediterranean Sea), Truc Vert and La Tresson beaches (Atlantic Ocean), and Dewulf (English Channel). The results focus on decadal and multi-annual beach trends at the Truc Vert beach site. There is almost no trend in beach volume at Truc Vert beach, although there is a variation in this parameter on a cycle of 2 to 3 yr, with variations related to wave energy and probably to indexes of climate variability. Numerical modelling identified the sensitivity of beach responses to changes in wave height and direction, especially in terms of subtidal morphology and the potential development of shoreline instability. Together with the observed offshore wave angle at the Biscay Buoy, these model results suggest that a potential change in wave angle due to climate variability could significantly modify the bars' morphology. The combination of data analysis and numerical modelling contributed to the development of vulnerability indexes designed for sandy coasts, which take into account climate-dependant variables such as waves. This allowed the differentiation of the sites in terms of vulnerability to erosion: Sète Lido and Truc Vert beach were the most and least vulnerable sites, respectively. These indexes help in identifying the dominant components of beach vulnerability, and provide potential for the study of how anthropogenic factors affect vulnerability. The study of stakeholder perceptions and decision-making with regard to climate-related risk also highlighted potential anthropogenic effects on beach vulnerability, and identified possible site-specific outcomes.
ISSN: 0936-577X

hal-00843946
https://hal-brgm.archives-ouvertes.fr/hal-00843946
DOI : 10.3354/cr01153

Éditeur(s) : HAL CCSD Geological Society of America
Résumé : International audience
Lakes are major depositional systems for which the related depositional processes have long been considered relatively simple. Breaking this statement, this study presents a detailed analysis of deposits in Lake Saint-Jean, the third largest natural lake in Québec. In addition to postglacial deltaic and coastal depositional systems fringing the lake, current-controlled features such as a large subaqueous prograding wedge and three sediment drifts have been identifi ed in its central portion based on two-dimensional (2-D) acoustic high-resolution subbottom profiles. The large subaqueous prograding wedge is a 4-km-long and up to 15-m-thick heterolithic shelf-like construction in the southeastern part of the lake. The three sediment drifts are 0.1–0.5-km-long and 2–5-mthick mud mounds distributed on the lake floor in the central portion of the lake. Diatom analyses and radiocarbon dating show that the development of these current-controlled features occurred during the lacustrine phase, after the disconnection with the postglacial marine Laflamme Gulf at 8.5 cal. k.y. B.P. Depositional facies show evidence of recurrent bottom-current activity. Related deposits alternate with pelagic sedimentation stages characterized by the settling of mud and biogenic accumulations. We investigated the origin of bottom currents using a numerical simulation (SYMPHONIE, an oceanographic model), with the aim of modeling wind-induced lake-scale water circulation. Simulations suggest that the subaqueous prograding wedge and the three sediment drifts result from wind-induced bottom currents generated by storm events having wind speed greater than 10 m s–1. Such strong winds are able to significantly affect sedimentation in the central portion of Lake Saint-Jean. Theresulting wind-induced sedimentary features were integrated into a refi ned lacustrine depositional model that summarizes the evolution of a group of water bodies referred to as “wind-driven water bodies.” This study applies a new tool for lake strata characterization and highlights the potential diffi cultyin differentiating them from marine deposits in the geological record.
ISSN: 0016-7606

insu-01184724
https://hal-insu.archives-ouvertes.fr/insu-01184724
DOI : 10.1130/B31145.1

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Marine biological invasions threaten biodiversity worldwide. Here we explore how Marine Protected areas, by reducing human use of the coast, confer resilience against the introduction of non-indigenous species (NIS), using two very different Pacific islands as case studies for developing and testing mathematical models. We quantified NIS vectors and promoters on Vancouver (Canada) and Moorea (French Polynesia) islands, sampled and barcoded NIS, and tested models at different spatial scales with different types of interaction among vectors and between marine protection and NIS frequency. In our results NIS were negatively correlated with the dimension of the protected areas and the intensity of the protection. Small to medium geographical scale protection seemed to be efficient against NIS introductions. The likely benefit of MPAs was by exclusion of aquaculture, principally in Canada. These results emphasize the importance of marine protected areas for biodiversity conservation, and suggest that small or medium protected zones would confer efficient protection against NIS introduction.
ISSN: 2045-2322

hal-01381251
https://hal-univ-perp.archives-ouvertes.fr/hal-01381251
https://hal-univ-perp.archives-ouvertes.fr/hal-01381251/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01381251/file/rate%20of%20biological%20invasions.pdf
DOI : 10.1038/srep33013

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Existen condiciones de competencia internacional que han afectado negativamente el comportamiento del flujo turístico norteamericano al Caribe Mexicano, ello ha puesto en evidencia la vulnerabilidad del modelo tradicional basado en la oferta de “sol y playa”, que se ha agrava en la cuenca del Caribe porque todos los destinos de ella compiten con el mismo modelo. Por dicha razón es necesario replantear nuevas formas de sustentar el desarrollo del turismo, a partir de descentralizar políticas, funciones y gestión administrativa de los tres niveles de gobierno, para buscar con ello, sinergias de fortalecimiento regional, que permitan potenciar la diversificación de oportunidades de desarrollo con nuevos atractivos y ofertas generadas desde los mercados locales. Con esta estrategia será posible ganar la sostenibilidad de la economía regional y estatal a corto y mediano plazo y, con ello consolidar el desarrollo de una sustentabilidad plena en el largo plazo.
La concurrence internationale sur le marché touristique a des effets négatifs sur le comportement des flux touristiques américains sur les rivages caribéens du Mexique. La massification des flux a mis en évidence les limites du modèle traditionnel basé sur l'offre « soleil et plage » commune à l’ensemble de l’espace caribéen. Pour cette raison, il est nécessaire de repenser de nouvelles façons de soutenir le développement du tourisme, de la décentralisation des fonctions politiques et administratives des trois paliers de gouvernement, et de chercher à renforcer les synergies régionales pour renforcer les possibilités de diversification du développement autour de nouvelles attractions et offres provenant des marchés locaux.Cette stratégie permettra de promouvoir la durabilité de l'économie régionale et d'État et de consolider un projet de développement viable à long terme.
The competition on the international tourism market has negative effects on the behavior of American’ tourist flows on the Caribbean coast of Mexico. The mass flows has highlighted the limitations of traditional model based on the offer "sun and beach" common throughout the Caribbean area. For this reason, we need to rethink new ways to support development tourism, the decentralization of political and administrative functions of the three levels of government, and seek to strengthen regional synergies to enhance diversification opportunities around the development of new attractions and offers from local markets.This strategy will promote the sustainability of the regional economy and state and consolidate a sustainable development project in the long term.
Mexique

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.4208
http://journals.openedition.org/etudescaribeennes/4208

Résumé : Ce travail est l'expression d'une volonté de chercheurs, de la Carabe d'améliorer les connaissances scientifiques méso- et micro-météorologiques appliquées aux milieux insulaires sous influence des alizés et de développer la recherche dans ces domaines.On sait que le phénomène météorologique le plus remarquable impactant les îles de la Caraïbe reste le cyclone tropical. Mais d'autres phénomènes, a des échelles inferieures, telles que les pluies intenses, les houles, la dégradation de la qualité de l'air ont une importance aigüe en termes de risques naturels ou de risques sur la sante. Ces exemples attestent la nécessité d'utiliser des méthodes de descente d'échelle pour exploiter l'information météorologique et/ou climatique de grande échelle et dériver des scenarios locaux et régionaux appliques aux territoires insulaires. Ce défi est important car l'attente d'analyses scientifiques pertinentes dans ces domaines est grande.Les travaux présentés dans ce mémoire ont pour principaux objectifs la simulation numérique puis l'analyse des mécanismes méso- et micro-échelles qui induisent des circulations locales diurnes et nocturnes sur l'archipel de la Guadeloupe à l'aide de codes numériques météorologiques éprouves car largement utilises en recherche et en prévision opérationnelle.Ils constituent donc la première étude de modélisation numérique à haute résolution en basse atmosphère, par descente d'échelle dynamique, pour des intervalles d'espace compris entre 1 km et 111 m sur cet archipel.Le modelé atmosphérique Weather Research and Forecasting ARW V3.4 (WRF ARW), non-hydrostatique, a été utilise pour l'ensemble des simulations pour modéliser la troposphère depuis l'échelle globale à l'échelle de la turbulence.Trois situations météorologiques classiques réelles d'une durée de 48 heures, correspondant à 80 % des situations météorologiques observées dans la zone, alizes soutenus (AS), alizes moyens (AM), alizes faibles (AF) ont été examinées. Ces situations sont caractérisées par les valeurs du nombre de Froude local suivantes : 0,82 (AS), 0,41 (AM) et 0,21 (AF). Six domaines de modélisation ont été sélectionnés pour effectuer les descentes d'échelle dynamiques : D01 (maille de 27 km), D02 (maille de 9 km), D03 (maille de 3 km), D04 (maille de 1 km), D05 (maille de 333 m) et D06 (maille de 111 m) avec soixante-dix niveaux verticaux. Les quatre premiers domaines (D01 à D04) couvrent l'archipel de la Guadeloupe et sont utilisés en mode méso-échelle à l'aide d'un schéma d'ensemble de couche limite planétaire YSU. Les domaines D05 (couvrant l'île de la Basse-Terre et le centre de l'archipel) et D06 (couvrant la zone littorale et rurale du Petit Cul-de-Sac Marin et la zone urbaine de l'agglomération pointoise) sont utilisés en mode Large Eddy Simulation avec une fermeture de la turbulence 1,5 TKE 3D. Le modèle WRF a été forcé toutes les six heures par l'assimilation des champs d'analyses globales du modèle NCEP FNL (1° de résolution). Les simulations effectuées ont permis d'obtenir des champs de variables météorologiques 10-minutes à très hautes résolutions spatiales.Les résultats des simulations méso- et micro-échelles ont été confrontés aux valeurs expérimentales obtenues à l'aide de capteurs places sur des mâts météorologiques (campagne Atmo-Mangrov et réseau de mesure Météo-France). Il s'agissait d'optimiser l'utilisation des couplages de codes numériques tout en conservant la possibilité de les confronter aux observations expérimentales.Les résultats des simulations numériques micro-échelles, des différents cas (AS, AM, AF) sont utilisées pour forcer (c'est-à-dire définir les conditions limites) un modèle lagrangien de dispersion de particules : FLEXPART. Le système couple FLEXPART-WRF a été employé dans le domaine D06 pour étudier la dispersion du panache d'oxydes d'azote émis par la principale usine de production d'électricité de l'île.
The present work expresses the will of Caribbean researchers to improve the meso- and micro-meteorological scientific knowledge of the trade winds influenced island areas, and to develop research in these domains.It is well known that tropical hurricanes remain the most remarkable meteorological phenomena that affect the Caribbean islands. But some other phenomena, of smaller scale, such as intense rainfall events, swells, or air quality degradation, are of extreme importance for natural or health hazards. These examples show the need to use downscaling methods to exploit large scale meteorological or climatic information, and to obtain local and regional scenarios for the island areas. This is an important challenge, as sound scientific studies in these matters are eagerly expected. The aim of the research works exposed in the present dissertation is numerical simulation and analysis of the meso- and microscale mechanisms that induce diurnal and nocturnal local circulations in the Guadeloupe archipelago, using numerical meteorological models that are widely used in research and in operational forecasting.These works represent the first high-resolution (1 km to 111 m) numerical study of the lower atmosphere over the Guadeloupe archipelago. The Weather Research and Forecasting ARW 3.4 (WRF-ARW) model is used to simulate the troposphere from global scale to turbulence scale. Real cases of three typical weather types (80% of cases during a year) are examined during 48 hours : strong trade winds (STW), medium trade winds (MTW) and weak trade winds (WTW). These weather types are characterized by values of the local Froude number : 0.82 (STW), 0.41 (MTW) and 0.21 (WTW). Six domains have been selected for the dynamical downscaling : D01 (grid spacing of 27 km), D02 (grid spacing of 9 km), D03 (grid spacing of 3 km), D04 (grid spacing of 1 km), D05 (grid spacing of 333 m) and D06 (grid spacing of 111 m), including 70 vertical levels. The first four domains (D01 to D04) cover the Guadeloupe archipelago and are used in the meso-scale simulations with the planetary boundary layer scheme YSU (ensemble mean). Domain D05 (covering the Basse-Terre island and the middle of the archipelago) and domain D06 (covering the coastal and rural area of Le Petit Cul-de-Sac Marin and the urban area of Pointe-à-Pitre), are employed in the micro-scale simulation (LES) with the 3D TKE 1.5 order closure scheme. WRF has been 6 hourly reinitialized with the NCEP FNL global analyses (resolution of 1°). These simulations permitted to obtain 10-minutes meteorological variable fields with a very high resolution (111 m).Meso-scale and micro-scale model results have been evaluated with observational data from meteorological stations (field campaign Atmo-Mangrov, French Met Office).Once validated, the micro-scale model outputs have been used for the assimilation of the lagrangian particle dispersion model : FLEXPART. The coupling FLEXPART-WRF has been employed in domain D06, in order to analyze the dispersion of the nitrogen oxide plume emitted by the main power plant of the archipelago.

http://www.theses.fr/2014AGUY0735/document

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : A partir d’une étude comparée originale qui met en perspective des expériences insulaires prises en Corse et en Martinique, cette communication interroge la portée de l’éco-tourisme comme alternative au tourisme de masse pour les territoires insulaires français. Les deux destinations touristiques sont tout d’abord présentées brièvement : l’examen du type de tourisme développé et de ses conséquences socio-spatiales amène à discuter, pour chacune des îles, l’existence d’une attente sociétale prégnante pour faire du tourisme autrement. Il est ensuite montré que le positionnement des pouvoirs publics en matière de tourisme alternatif, qui reste de l’ordre du discours, incite les acteurs locaux à mener leurs propres projets. Or, en matière de développement local, les retombées de ces initiatives locales, éparses et disjointes, sont somme toute très faibles. Ces constats conduisent à la présentation d’un modèle conceptuel d’écotourisme pour les territoires insulaires, qui cherche autant à clarifier la définition de l’écotourisme qu’à ouvrir la discussion sur des recommandations pour aller vers plus de durabilité.
From a comparative study of original that puts into perspective the experiences made in Corsica and Martinique islands, this paper questions the scope of eco-tourism as an alternative to mass tourism to the French islands. Both destinations are first presented briefly review the type of developed tourism and its socio-spatial causes discussed for each of the islands, there is a societal expectation pregnant for another type of tourism. It is then shown that the position of the government in terms of alternative tourism, which remains the order of discourse, encourages local actors to pursue their own projects. However, in terms of local development, the impact of these local initiatives, scattered and disjointed, are in fact very low. These observations lead to the presentation of a conceptual model for ecotourism island territories, which seeks both to clarify the definition of ecotourism is to open the discussion on recommendations for moving towards sustainability.
Corse
Martinique

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.5303
http://journals.openedition.org/etudescaribeennes/5303

Éditeur(s) : HAL CCSD Wiley
Résumé : Sodium, an element which is needed by animals but often toxic in high concentrations to plants, may be deficient and limit animal abundance in inland continental regions, but may be overabundant and limit plant productivity in coastal regions. Here we present data from 50 independent plots (including leaf data from more than 2480 individual trees) showing that leaves in the Amazon basin uptake high amounts of sodium (Na) in a manner more similar to the essential cation potassium (K) than to the toxic cation aluminium (Al). Leaf Na increases linearly with soil Na concentrations, and there is no apparent mechanism for selective exclusion of Na in comparison to K, a key attribute of halophytes. This indicates that the Amazon basin is broadly non-halophytic and increased sodium concentrations in non-halophyte plants often decrease plant productivity. Total Na concentrations are approximate to 10 times higher in coastal regions than inland regions. Such concentration gradients in nutrients may have been reduced in the past because large animals that were abundant in the Pleistocene have been hypothesized to play a large role in reducing nutrient concentration gradients at continental scales. We use a diffusion model and a Na loss rate based on empirical data to estimate that large animals may have moved significant quantities of Na inland away from coastal regions in the Amazon Basin. Therefore, our simple model suggests that large animals may play an important, yet diminishing, role in maintaining the sodium balance of the planet.
ISSN: 0906-7590

hal-01531615
https://hal.archives-ouvertes.fr/hal-01531615
PRODINRA : 349612
DOI : 10.1111/ecog.01589