Résumé : After a period of rapid development of the sites (an increase in both reared surface area and production), tropical shrimp aquaculture is currently being faced with critical problems due to economical and ecological constraints. In many countries with favourable conditions for shrimp aquaculture such as indonesia or Vietnam, sites are often badly selected and/or over-exploited. This conducts to sorne extent to decreases or collapses in the production due to the difficulty in predicting the maximum production capacity of the sites. Furthermore, it appears that production sustainability depends on many factors among which socio-economy and ecolo gy are of prime importance. The STD3 project titled « Assessment of tropical shrimp aquaculture impact on the environment in tropical countries using hydrobiology, ecology and remote sensing as helping tools for diagnosis )) was initiated in 1994, with the aim to study the sustainability of marine shrimp aquaculture in tropical areas, main! y Indonesia and Vietnam, through the following tasks: (i) improve site selection and study the impact of aquaculture on marine environments presenting a variable sensitivity to organic sewage, (ii) analyse the socio-economical aspects and profitability of the aquaculture industry and of common resources (iii) use remote sensing and geographical data bases for diagnosis and monitoring of site degradation (iv) reinforce the capacity of Asian scientists through training. Severa! aquaculture sites have been investigated in the Lampung region (South Sumatra, Indonesia), the Mekong delta (Vietnam) and on the West coast of New-Caledonia, providing a large range of typical ecosystems encountered in Asia and in the Pacifie, from coralline sites to coastal plains with mangrove and deltaic areas. The study concerned the spatial structure and seasonal influence of these ecosystems, the temporal variation during the course of the project (3 years) and the relation between the ecological structure and farm productions. Remote sensing provides a synoptic vision over large land expanses. Severa! scenes were processed for landuse mapping using conventional classification techniques. Concerning water quality assessment, a general relation for the Java sea was found between image and field data in terms of total suspended matter. Applying this relation to a new site in Sumatra has provided an initial approach to water type and, together with land use mapping, a preliminary assessment of the suitability of the area to shrimp aquaculture development. Socio-economic research has been focused on the identification ofneeds for collective action, including public policy, in the perspective of shrimp farming sustainability. The main concern is in the regulation of shrimp farming intensification and extensification at the scale of coastal ecosystemic entities in a common property resource management perspective. The common considered here is coastal water quality. Comparing the local development profiles and the institutional grounds for the design and implementation of collective management rules shows that variables such as land tenure system, farm owner socio-economic profile, social homogeneity or heterogeneity of the farmers are key factors to analyse the potential for sustainability. The defmition of water quality and the possible means to ensure its collective management are discussed. The main conclusion is that the economie incentives to farming development are strong but there is no significant difference among traditional, semi-intensive and intensive systems in terms of economie efficiency or wealth distribution. The description of the functioning of the different kinds of ecosystems make it possible to give an advice concerning the positioning of the activity inside the ecosystem, and furthermore to have a reference state in order to determine the impact of the activity on the coastal environnement. This impact can be summarized as an increase in the concentration of total suspended matt€?r, of particulate organic matter and of sulfate reducing bacterias. This organic ma~.er is either issued from rearing activities or from telluric origine, due to mangrove eradication when building the ponds. An evaluation of the relationship existing between productivity and characteristics of each ecosystem bas been conducted by correlating ecological indicators data (concentration of total suspended matter, particulate organic matter, chlorophyll, percentage of pheopigments in total pigments and cyanobacteria and sulfatereducing bacteria in water and sediments) with the average production of the farms. This comparison lead to the compilation of a scale of observed production integrating the range of these environmental parameters with shrimp production levels, bound to facilitate the positioning of shrimp farming in relation with the confmement leve! of each ecosystem. Lastly, ali geographie data originated from the various compartments of the study have been geo-referenced and loaded into a geographical information system. This allows to display any query made on spatial variables and their related statistical data, including the ir variations over the last few years and to reveal patterns and phenomena otherwise not obvious.
Le programme mis en oeuvre par la DRV (Paris, CREMA-L'Houmeau, DELIAO Brest, COP Tahiti, GIE/RA Nouvelle Calédonie), dans le cadre d'un projet européen STD3 «(Sciences et Technique au Service du Développement», en collaboration avec l'Université de Montpellier II, l'Ecole Nationale d'Agronomie de Rennes, l'ITC (Hollande), l'Institut Océanographique de Nha Trang (Vietnam), le BADC de Jepara et le BPPT de Jakarta (Indonésie), avait pour but la mise au point de méthodes permettant d'améliorer la sélection des sites ainsi que le suivi du développement et de l'impact de l'aquaculture des crevettes Péneides en milieu tropical pour éviter la surexploitation. Quatre axes de recherche ont été défmis : a) identifier la nature et quantifier les rejets de déchets issus de ce type d'aquaculture, b) définir les caractéristiques écologiques des écosystèmes susceptibles d'accueillir l'activité aquacole et suivre leur évolution sous l'influence des rejets, c) déterminer l'influence de la gestion des fermes et des ressources (aspects économiques) sur les performances de productivité, d) déterminer la capacité de la télédétection comme outil de diagnostic d'impact à l'échelle de la région, e) mener un programme de formation d'étudiants et jeunes chercheurs Vietnamiens et Indonésiens.

Droits : 1998 Ifremer
http://archimer.ifremer.fr/doc/00132/24357/22357.pdf
http://archimer.ifremer.fr/doc/00132/24357/

Éditeur(s) : HAL CCSD
Résumé : International audience
Human spatial motions determine geographic social contacts that influence the way an information is spread on a population or a community. As mobility is a transverse dimension to social practices it is important to better understand its role. With the Eternal-Return model we propose, we simulate an artificial world populated by heterogeneous agents who differ in their mobility. We have chosen a multi-agent framework perspective for this simulation. We endow the agents with simple rules on how to move around the space and how to establish proximity-contacts. This allows to distinguish different kinds of mobile agents, from sedentary ones to travelers. To summarize the dynamics induced by mobility over time, we define the mobility-based Social Proximity Network as being the network of all distinct contacts between agents. Its properties give insight in the process of information spreading. We conduct simulations to understand how an information can be broadcast when agent-nodes are in motion.
IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining
Niagara falls, Canada

hal-00874344
https://hal.archives-ouvertes.fr/hal-00874344

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
ISSN: 0362-546X

hal-00699203
https://hal.archives-ouvertes.fr/hal-00699203

Résumé : This study aims to integrate the problems associated with port development and related activities in an economic monitoring programme that surveys all the activities associated with the marine environment. The economic monitoring programme in this sector also includes studying coastal spatial planning. This type of study concerns the creation and remodelling of sites that involve investments. We can consider two types of coastal spatial planning: one which integrates port development, tourism, aquaculture and fisheries and one that deals with the marine environment (Abric, 1989). Economic surveys of port development on French coasts supposes that the problem of identifying information sources have been resolved and the sectors and the activities that should be accounted for have been characterised. In what follows, the limits of available information and the problems pertaining to the proposed classification of activities according to statistical nomenclature will be discussed. The absence of structured and localised data is aggravated in certain cases by the rules of confidentiality. In light of these difficulties, the first part of this report is devoted to the inventory of general information sources and to the characterisation of existing data. As information forms the basis of any economic monitoring programme, it is necessary to know where, how and by whom information is processed and the limits that one comes up against. This report does not pretend to be exhaustive given the deadlines and the duration of this study. The second part of this report constitutes a summary of the recent trends discerned in terms of port development, from a legal, as well as economic and financial, point of view. This study should be considered as the first step to establishing a basis for a more in-depth study.
Cette étude a pour but d'intégrer les problèmes d'aménagement portuaire et les activités qui y sont liées dans un suivi conjoncturel de l'ensemble des activités économiques en relation avec le milieu maritime. Le suivi conjoncturel de ce secteur économique passe aussi par l'étude de l'aménagement physique du littoral. Celui-ci concerne la création et le remodelage de sites impliquant des investissements. On peut considérer deux types d'aménagements physiques -l'aménagement du littoral : portuaire, touristique, aquacole, halieutique; -l'aménagement du mineur marin (Abric, 1989). Un suivi conjoncturel de l'aménagement portuaire du littoral français, suppose en préalable la résolution du problème de l'identification des sources d'information et la caractérisation des secteurs et activités en prendre en compte. On verra par la suite les limites de l'information disponible et les problèmes afférents a la classification des activités selon les nomenclatures statistiques proposées. L'absence de données structurées et localisées est aggravée dans certains cas par des règles de confidentialité. Du fait de ces difficultés, la première partie de ce rapport est consacrée au recensement des sources d'information générale et à la caractérisation des données existantes. L'information étant à la base de tout suivi conjoncturel, il convient en effet d'être en mesure de savoir où, par qui et comment elle est traitée et les limites auxquelles on se heurte. Ce rapport ne peut prétendre à l'exhaustivité compte tenu des délais et de la période d'exécution de cette étude. La seconde partie constitue une première synthèse sur les évolutions récentes saisies en termes d'aménagements portuaires, tant d'un point de vue juridique qu'économique et financier. Cette étude est à considérer comme une première étape destinée à poser les bases pour une étude plus approfondie. [OCR NON CONTRÔLE]

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1992/rapport-4169.pdf
http://archimer.ifremer.fr/doc/00000/4169/

Éditeur(s) : HAL CCSD Institute of Electrical and Electronics Engineers
Résumé : International audience
We show that the slope introduced by DeGiorgi-Marino-Tosques is stable with respect to the variational convergence introduced by Wijsman. Applications to the stability of subdifferentials at critical points and to subdifferential sum rules are derived.
ISSN: 0018-9219
Las Vegas, United States

Droits : info:eu-repo/semantics/OpenAccess
hal-00699033
https://hal.archives-ouvertes.fr/hal-00699033
https://hal.archives-ouvertes.fr/hal-00699033/document
https://hal.archives-ouvertes.fr/hal-00699033/file/S_IEEE02.pdf