Éditeur(s) : Pergamon-elsevier Science Ltd
Résumé : Sites of monomethylmercury (MMHg) production in Amazonian regions have been identified in hydraulic reservoirs, lake sediments and wetlands, but tailings ponds have not yet received sufficient attention for this purpose. This work evidenced high MMHg production within the water column and the interstitial water of two tailings ponds of French Guiana Au mines located; (i) in a small scale exploitation (Combat) where Hg was used for Au amalgamation, and (ii) in an industrial on-going Au mine (Yaoni) processing without Hg. The (MMHg)(D) maximum (2.5 ng L-1) occurred in the oxic water column above the sediment-water interface (SWI) of the most recent tailings pond (Combat), where the substrate was fresh, the redox transition was sharp and the pool of total Hg was large. In the Yaoni pond, the (MMHg)(D) maximum concentration (1.4 ng L-1) was located at the SWI where suboxic conditions prevailed. Using the (MMHg)(D) concentration as a proxy for Hg methylation rates, the present results show that Hg methylation may occur in various redox conditions in tailings ponds, and are favored in areas where the organic matter regeneration is more active. A 3-month long laboratory experiment was performed in oxic and anoxic boxes filled with high turbidity waters from the Combat Au mine to simulate tailings ponds. Slaked lime was added in an experimental set (2 mg L-1)and appeared to be very efficient for the reduction of suspended particulate matter (SPM) to environmentally acceptable concentrations. However, at the end of the experiment, large (MMHg)(D) concentrations were monitored under treated anoxic conditions with the (MMHg)(D) maximum located at the SWI above the Fe-reducing zones. No (MMHg)(D) was detected in oxic experiments. The use of slaked lime for SPM decantation appears to be an efficient and non-onerous process for Au miners to avoid Hg methylation in tailings ponds when it is combined with rapid drainage of the mine waters. A subsequent human intervention is however necessary for the recovery of soil structure through the cover of dried ponds with organic rich materials and reforestation to avoid the stagnation of rain waters and the occurrence of anoxia. (C) 2010 Elsevier Ltd. All rights reserved.
Applied Geochemistry (0883-2927) (Pergamon-elsevier Science Ltd), 2011-02 , Vol. 26 , N. 2 , P. 222-229

Droits : 2010 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/00030/14117/12133.pdf
DOI:10.1016/j.apgeochem.2010.11.022
http://archimer.ifremer.fr/doc/00030/14117/

Éditeur(s) : HAL CCSD Wiley
Résumé : A standardized rapid inventory method providing information on both tree species diversity and aboveground carbon stocks in tropical forests will be an important tool for evaluating efforts to conserve biodiversity and to estimate the carbon emissions that result from deforestation and degradation (REDD). Herein, we contrast five common plot methods differing in shape, size, and effort requirements to estimate tree diversity and aboveground tree biomass (AGB). We simulated the methods across six Neotropical forest sites that represent a broad gradient in forest structure, tree species richness, and floristic composition, and we assessed the relative performance of methods by evaluating the bias and precision of their estimates of AGB and tree diversity. For a given sample of forest area, a several small' (<1ha) sampling strategy led to a smaller coefficient of variation (CV) in the estimate of AGB than a few large' one. The effort (person-days) required to achieve an accurate AGB estimate (<10% CV), however, was greater for the smallest plots (0.1ha) than for a compromise approach using 0.5ha modified Gentry plots, which proved to be the most efficient method to estimate AGB across all forest types. Gentry plots were also the most efficient at providing accurate estimates of tree diversity (<10% CV of Hill number). We recommend the use of the 0.5ha modified Gentry plot method in future rapid inventories, and we discuss a set of criteria that should inform any choice of inventory method.
ISSN: 0006-3606

hal-01032408
https://hal.archives-ouvertes.fr/hal-01032408
DOI : 10.1111/btp.12006

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Regeneration of artificially induced lesions was monitored in nubbins of the branching coral Acropora muricata at two reef-flat sites representing contrasting environments at Réunion Island (21u079S, 55u329E). Growth of these injured nubbins was examined in parallel, and compared to controls. Biochemical compositions of the holobiont and the zooxanthellae density were determined at the onset of the experiment, and the photosynthetic efficiency (F v /F m) of zooxanthellae was monitored during the experiment. Acropora muricata rapidly regenerated small lesions, but regeneration rates significantly differed between sites. At the sheltered site characterized by high temperatures, temperature variations, and irradiance levels, regeneration took 192 days on average. At the exposed site, characterized by steadier temperatures and lower irradiation, nubbins demonstrated fast lesion repair (81 days), slower growth, lower zooxanthellae density, chlorophyll a concentration and lipid content than at the former site. A trade-off between growth and regeneration rates was evident here. High growth rates seem to impair regeneration capacity. We show that environmental conditions conducive to high zooxanthellae densities in corals are related to fast skeletal growth but also to reduced lesion regeneration rates. We hypothesize that a lowered regenerative capacity may be related to limited availability of energetic and cellular resources, consequences of coral holobionts operating at high levels of photosynthesis and associated growth.
ISSN: 1932-6203

hal-01369712
http://hal.univ-reunion.fr/hal-01369712
http://hal.univ-reunion.fr/hal-01369712/document
http://hal.univ-reunion.fr/hal-01369712/file/journal.pone.0072618.PDF
DOI : 10.1371/journal.pone.0072618

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Cyanobacteria and their toxins are known as a health hazard in recreative and distributed waters. Monitoring data from 2004 to 2011 were collected at regional scale to characterize exposition parameters to microcystins in Brittany (Western France). The data show that cyanobacteria populations are experiencing a composition shift leading to a longer duration of cell densities higher than WHO alert levels 2 and 3. Microcystins however appear to be more frequently detected with subacute concentrations in low cell density samples than in high cell density samples or during bloom episodes. Positive relations are described between microcystin concentrations, detection frequencies and cyanobacteria biovolumes, allowing for a novel definition of alert levels and decision framework following WHO recommendations
ISSN: 1438-4639

hal-01255825
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01255825
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01255825/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01255825/file/Improving%20microcystin%20monitoring%20relevance%20in%20recreative%20waters%20A%20regional%20case-study%20%28Brittany%2C%20Western%20France%2C%20Europe%29.pdf
DOI : 10.1016/j.ijheh.2015.12.004

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : The current consensus on Sustainable Tourism Development emphasizes the necessity for all tourist planning and policy making decisions to consider the impacts of tourism activity on all three dimensions of sustainability: economic efficiency referring to the capacity of an economy to be competitive, social justice aiming at the better distribution of produced welfare in the society and environmental preservation as the conservation of ecosystem’s capacity to provide humans with goods and services essential for their survival.A successful evaluation of the tourism activity presupposes the extensive examination of certain elements of the tourism product itself (expressed as characteristics of supply, demand and the organization of the tourist market), along a series of parameters related directly to the tourism products (effects), and indirectly to its implications for the destination (impacts). This paper presents a methodological framework for an integrated evaluation and monitoring of the tourism activity, in support of planners and policy makers towards both tourism and regional policy.A case study on the island of Samos in Greece is employed to demonstrate the scope of the methodology based on real data, its potential value but also its limits. The results of the study indicate that tourism remains the main developmental force in the island for over two decades without unfortunately, succeeding to deviate from the rule of decreasing tendencies, of similar mass tourism destination.
Le consensus actuel sur le développement du tourisme durable met l’emphase sur la nécessité pour tous les porteurs de projets et décideurs de prendre en compte les impacts de l’activité touristique sur les trois dimensions de la durabilité : l’efficience économique se réfère à la capacité d’une économie à être compétitive, la justice sociale aspire à une meilleure redistribution des richesses au sein de la société et la préservation de l’environnement concerne la préservation de la capacité des écosystèmes à fournir aux humains les biens et services essentiels à leur survie.Une évaluation réussie de l’activité touristique présuppose un examen exhaustif de certains éléments du produit touristique en lui-même (caractéristiques de l’offre, de la demande et de l’organisation du marché touristique), ainsi qu’une série de paramètres liée directement au produit touristique (effet). Il faut également prendre en compte les implications directes et indirectes du développement touristique de la destination (impacts). Cette recherche présentera un cadre méthodologique pour l’évaluation et la gestion intégrée de l’activité touristique, pour accompagner l’élaboration de politiques publiques et ce tant au niveau du tourisme que des politiques régionales.Une étude de cas réalisée sur l’île de Samos en Grèce sera utilisée pour démontrer la portée de la méthodologie utilisée (basée sur des résultats réels), sa valeur potentielle, ainsi que ses limites. Les résultats de l’étude indiquent que, depuis deux décennies, le tourisme est la principale force de développement de l’île sans, malheureusement, déroger à la règle des tendances à la baisse qui affecte également d’autres destinations touristiques similaires.
Grèce
Samos

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.6257
http://journals.openedition.org/etudescaribeennes/6257

Éditeur(s) : HAL CCSD Wiley
Résumé : Revue de rang A
International audience
This paper studies how to detect anomalies in a distributed manner by using wireless sensor networks (WSNs). We focus on a medical context, where the existing works generally provide large environments to monitor patients using sensors as simple transducers. Those devices forward sensed health parameters to a main base station. This station collects received data and may perform some computations. In this paper, we perform some distributed tasks on the sensors. We propose a distributed algorithm, which allows to raise alarms under some initial rules to alert efficiently medical staff in case of critical situations without needless warnings. Each mote monitors a parameter. When this parameter reaches an abnormal value, the mote communicates with other motes in order to check if it is a ‘local' anomaly or if the patient is in an abnormal situation. In such cases an alarm is raised. We implemented our algorithm over a network of micaZ sensors running under TinyOS. The obtained results show promising perspectives.
ISSN: 1532-0626

hal-00519594
https://hal.archives-ouvertes.fr/hal-00519594
DOI : 10.1002/cpe.1583

Éditeur(s) : Elsevier Science Bv
Résumé : Underwater video techniques are increasingly used in marine ecology studies. Technological progress regarding video cameras, sensors (such as sounders), battery life and information storage make these techniques now accessible to a majority of users. However, diver-based underwater visual censuses, and catch and effort data, remain the most commonly used for observing coastal biodiversity and species. In this paper, we review the underwater video techniques that have been developed since the 1950s to investigate and/or monitor coastal biodiversity. Techniques such as remote underwater video, whether baited or not, diver-operated video and towed video are described, along with corresponding applications in the field. We then analyse the complementary of techniques, first from studies comparing video techniques with other observation techniques, whether video-based or not, and second by documenting their respective cost efficiencies. These findings are discussed with respect to current challenges in monitoring and investigating coastal biodiversity. Video should be more often considered and used, either in addition to or as an alternative to diver-based, fishing and acoustic techniques, as it may be particularly suited for monitoring coastal biodiversity in a variety of areas and on larger scales than hitherto and within an ecosystem-based approach to management and conservation.
Fisheries Research (0165-7836) (Elsevier Science Bv), 2014-06 , Vol. 154 , P. 44-62

Droits : 2014 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00181/29274/27901.pdf
DOI:10.1016/j.fishres.2014.01.019
http://archimer.ifremer.fr/doc/00181/29274/

Éditeur(s) : Elsevier
Résumé : Because Vibrio aestuarianus is known to cause serious infections in Pacific oyster Crassostrea gigas, a real-time PCR assay was developed targeting the dnaJ gene of this bacterium. Only V. aestuarianus strains isolated from C. gigas mortality events in different geographic areas and the reference strain tested positive, whereas no amplification products was obtained with type strains belonging to 23 other species of Vibrio. Sensitivity and reproducibility of the method were assessed using either seawater or oyster homogenate samples spiked with one V aestuarianus strain. All these samples were stored at -20 degrees C in order to mimic retrospective or grouped natural sample analysis without quantification bias due to prolonged freezing. Analysis of standard curves revealed excellent correlation values between light microscopy cell enumerations and PCR Threshold Cycle (Ct) values, and acceptable PCR reaction efficiencies for all type of samples. Quantification curves of both sample types were equivalent, with a detection level as low as 1.6 V. aestuarianus cells in the PCR reaction tube, corresponding to 1.6.10(2) cells ml(-1) and 1.6.10(2) cells mg(-1) in seawater and entire oyster samples, respectively, taking into account the dilution factor used for appropriate template DNA preparation. Comparison of PCR assay reproducibility according to the complexity of samples revealed that seawater samples gave more reproducible quantification measures than samples from oyster homogenate, with precision of measured Ct values inferior to 0.4 and 0.6 respectively at 99% confidence. Use of the real-time PCR assay allowed us to monitor V. aestuarianus load in oysters naturally infected with this pathogen. Furthermore, we were able to detect V aestuarianus in samples of seawater in which oysters had been reared and in algal cultures used for feeding oysters. Because of the rapidity and reliability of the real-time PCR assay method used in this study, just a few hours are needed compared with the two days required using the classic culture method, this technique will be particularly valuable in mollusc pathology laboratories, for monitoring the source and course of infections by V. aestuarianus in pathogenesis and epidemiologic studies, as well as for designing appropriate prophylactic control measures. (C) 2009 Elsevier B.V. All rights reserved.
Journal of Microbiological Methods (0167-7012) (Elsevier), 2009-05 , Vol. 77 , N. 2 , P. 191-197

Droits : 2009 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/2009/publication-6447.pdf
DOI:10.1016/j.mimet.2009.01.021
http://archimer.ifremer.fr/doc/00000/6447/

Éditeur(s) : Elsevier
Résumé : A study was conducted using a bioenergetics approach to generate information on energy requirement and feed utilization of Litopenaeus stylirostris. Animals (initial mean weight 21 +/- 1 g were fed ad libitum six experimental diets, ranging from 25 to 58% crude protein (CP), for 50 days. Weight gain increased from 21 to 30 g with increasing dietary protein level. Survival rates averaged 80%. Basal metabolism (HeE) and heat increment of feeding (HiE) were monitored using respirometry. HeE was on average I U shrimp(-1) day(-1) or 47 U kg live weight(-1) day (22 kJ/kg(0.8). d(-1)), slightly more than what is observed in fish. HiE averaged 0.2 W/sbrimp(-1) day(-1) or 10 W kg live weight(-1) day(-1) (4 kJ/kg(0.8) d(-1)). It represented 3 1 % and 12% digestible energy intake (DET) for shrimp fed on 58% CP and 25% CP diet respectively. Non-fecal (UE + ZE) energy calculated on the basis of N-ammonia excretion averaged 0.2 jig N-ammonia/g dry wt./ mn or 25 J live shrimp(-1) day(-1) in fasting stage and increased to 40 J in post-prandial stage. Ammonia production increased with increasing dietary crude protein (CP). The O:N ratio indicated that protein was increasingly used as an energy substrate as CP increased. The information was used to construct an energy budget for shrimp fed a protypical 40% CP diet. Gross energy intake (IE) was estimated at 6.5 W live shrimp(-1) day(-1); digestible energy intake (DEI) at 5, urinary and branchial excretion (UE +ZE) at 1.2, total heat production (HE) at 3.2; recovered energy (RE) at 0.6 (or 11% DEI). L. stylirostris adults issued from domesticated strain appeared to be more efficiently utilizing (i.e. converting into carcass energy) protein than carbohydrates. This preliminary energy budget can be used to construct theoretical feed requirement and waste outputs model for L. stylirostris. (C) 2007 Published by Elsevier B.V.
Aquaculture (0044-8486) (Elsevier), 2007-10 , Vol. 271 , N. 1-4 , P. 439-448

Droits : 2007 Published by Elsevier B.V.
http://archimer.ifremer.fr/doc/2007/publication-6263.pdf
DOI:10.1016/j.aquaculture.2006.05.062
http://archimer.ifremer.fr/doc/00000/6263/

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) : Wiley-blackwell
Résumé : 1. Abiotic and biotic variables of coastal lagoons are highly heterogeneous in both space and time, and this heterogeneity complicates the assessment of their ecological status. These variables are essential to the monitoring and preservation of these fragile ecotones and the resources and services they sustain. 2. An integrative approach for evaluating the ecological status of coastal lagoons, based on field investigations of the key parameters driving their functioning and a set of selected ecological indicators matching lagoon management information needs for societal benefits, is investigated. Consistency in lagoon status evaluation from multiple and different variables was estimated, through a case study comparing three adjacent yet contrasting French Mediterranean shallow water lagoons. 3. French Mediterranean shallow water lagoons are used to demonstrate the potential of such an approach and to underline the need for a multi-faceted framework, for correctly evaluating lagoon status, and underlining the need for high-frequency lagoon monitoring to avoid errors in status assessment and resulting management plans. 4. Based on the results, a continuous monitoring system is proposed that would record high frequency biotic and abiotic data in the lagoons. The use of such an ad hoc observatory system, based on appropriate diagnostic indicators and risk estimators would simplify interactions between scientists and managers and would improve the efficiency of their analyses. 5. A lagoon management plan based on a holistic approach is proposed to help scientists and local managers to reach a consensus about the set of ecological indicators to monitor in the lagoons needed to assess their global health status in accordance with both conservation and/or societal needs. Copyright (c) 2011 John Wiley & Sons, Ltd.
Aquatic Conservation-marine And Freshwater Ecosystems (1052-7613) (Wiley-blackwell), 2011-11 , Vol. 21 , N. 7 , P. 728-742

Droits : 2011 John Wiley & Sons, Ltd.
http://archimer.ifremer.fr/doc/00056/16702/14202.pdf
DOI:10.1002/aqc.1231
http://archimer.ifremer.fr/doc/00056/16702/

Éditeur(s) : HAL CCSD Springer Verlag (Germany)
Résumé : International audience
Mount Pinatubo volcano erupted in June 1991 in the main island of Luzon belonging to the Philippines archipelago. Huge economic losses and population exodus have followed. This major crisis has been relayed with other crises due to rainfed lahars which have been supplied with eruption deposits. These lahars have occurred every year since 1991 during the rainy season. They will probably last until 2005. After a brief presentation of the Philippine official response system to disasters, this paper draws up a critical analysis of the different kinds of institutional and social responses deployed to manage the different crisis and post-crisis phases of this event. Based on three viewpoints: from population, media and other actors, this analysis attempts to point out the strengths and weaknesses of the official management system, especially by studying the efficiency and the range of the solutions taken. So, it appears that the management of the June 1991 main crisis (eruption) was a success. On the other hand, difficulties have occurred with lahars risk management. Indeed, these lahars have obliged the authorities to protect and relocate thousands of people. In spite of persistent problems, the management system (monitoring/warning/evacuation) of lahar crises improves year after year. Failures appear especially within the rehabilitation program (protection/rehousing). Many direct (lack of means, preparedness, coordination, dialog,
etc.) and indirect (politico-administrative, socio-economic, cultural contexts) factors come together to lock the wheels of
the institutional response system. They defer the socio-economic start of this vital northern Philippines area.
GeoJournal

halshs-00119436
https://halshs.archives-ouvertes.fr/halshs-00119436
https://halshs.archives-ouvertes.fr/halshs-00119436/document

Éditeur(s) : EDP Sciences
Résumé : The diversity of reef ecosystems, the multiplicity of reef resource uses and the breadth of the range of the island socio-cultural contexts concerned make coral reef fisheries (CRF) management in the South Pacific a complex task. The health and state of the targeted resources depend both on ecosystem characteristics (as determined by ecological and biological factors) and on fishing pressure, whose effects are only partly known. Increasing harvests from commercial and recreational fishing increasingly overlap with traditional Subsistence activity, creating an important CRF management challenge. This paper presents a new approach to CRF assessment and monitoring by providing a set of multidisciplinary indicators. The fisheries system is assessed from three different viewpoints: ecology of targeted populations, exploitation and the broader socio-econornic fishery context. The use of complementary indicators chosen from each of these fields could balance the chronic lack of human and financial resources for the management of these fisheries. We suggest the use of these indicators through an assessment grid or an indicator dashboard specifically adapted to given situations and management objectives determined through a participatory approach. The operational efficiency of this dashboard depends on i) dialogue between users, ii) the objectivity of the proposed monitoring, iii) the Visual transcription of divergent/convergent interests amongst stakeholders, and iv) stakeholder involvement in the decision-making process. The use and constraints of such a tool are described with reference to Ouvea atoll (New-Caledonia, South Pacific) for which an analysis of available indicators for assessing fisheries status is presented.
La diversité des écosystèmes coralliens, la multiplicité des modalités d'exploitation de leurs ressources et l'hétérogénéité des contextes socio-culturels insulaires rendent complexe la gestion des pêcheries récifo-lagonaires du Pacifique sud. La santé et l'évolution de ces ressources dépendent, d'une part, des caractéristiques propres de l'écosystème (obéissant à des facteurs biologiques et écologiques) et, d'autre part, de la pression de pêche dont certains effets seulement sont établis. La pêche traditionnelle aux fins de subsistance est aujourd'hui concurrencée par des activités à visées commerciales et récréatives, qui accroissent les prélèvements et soulèvent de nouveaux enjeux de gestion. L'article propose une approche pour l'évaluation et le suivi de ces pêcheries basée sur un ensemble d'indicateurs pluridisciplinaires. Le système « Pêche » est analysé de trois points de vue complémentaires : l'écologie des peuplements exploités, l'exploitation halieutique sensu stricto et le contexte économique et social plus large des pêcheries. La mise en place d'indicateurs issus de ces trois domaines vise à compenser le manque chronique de moyens financiers et humains pour la gestion des pêcheries coralliennes des îles du Pacifique sud. Nous suggérons que leur utilisation s'effectue au travers d'une grille d'évaluation ou tableau de bord répondant à des situations précises et des objectifs de gestion définis lors d'une approche participative. La portée opérationnelle de ce tableau de bord de gestion de la pêche repose sur i) la concertation engagée entre les usagers, ii) l'objectivité du suivi préconisé, iii) la transcription visuelle des intérêts convergents et/ou divergents des acteurs, et iv) leur implication dans le processus de décision. Les modalités et contraintes d'application de cet outil sont décrites sur l'exemple de l'atoll d'Ouvéa (Nouvelle-Calédonie, Pacifique Sud), pour lequel une analyse des indicateurs disponibles pour décrire l'état des pêcheries a été réalisée.
Aquatic Living Resources (0990-7440) (EDP Sciences), 2005-07 , Vol. 18 , N. 3 , P. 199-213

Droits : 2005 EDP Sciences, IFREMER, IRD
http://archimer.ifremer.fr/doc/2005/publication-716.pdf
DOI:10.1051/alr:2005026
http://archimer.ifremer.fr/doc/00000/716/

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
Nowadays, technological advances in satellite imagery measurements as well as the development of dense geodetic and seismologic networks allow for a detailed analysis of surface deformation associated with active fault seismic cycle. However, the study of earthquake dynamics faces several limiting factors related to the difficulty to access the deep source of earthquake and to integrate the characteristic time scales of deformation processes that extend from seconds to thousands of years. To overcome part of these limitations and better constrain the role and couplings between kinematic and mechanical parameters, we have developed a new experimental approach allowing for the simulation of strike-slip fault earthquakes and analyze in detail hundreds of successive seismic cycle. Model rheology is made of multilayered visco-elasto-plastic analog materials to account for the mechanical behavior of the upper and lower crust and to allow simulating brittle/ductile coupling, postseismic deformation phase and far-field stress transfers. The kinematic evolution of the model surface is monitored using an optical system, based on subpixel spectral correlation of high-resolution digital images. First, results show that the model succeed in reproducing the deformation mechanisms and surface kinematics associated to the main phases of the seismic cycle indicating that model scaling is satisfactory. These results are comforted by using numerical algorithms to study the strain and stress distribution at the surface and at depth, along the fault plane. Our analog modeling approach appears, then, as an efficient complementary approach to investigate earthquake dynamics.
ISSN: 0278-7407

hal-01174176
https://hal.archives-ouvertes.fr/hal-01174176
DOI : 10.1002/2014TC003701

Éditeur(s) : HAL CCSD
Résumé : International audience
After the 2009 Morakot typhoon, which triggered numerous large landslides in Taiwan, Mouyen et al. (2013)showed for the first time the potential of time-lapse gravity survey to infer the mass of sediments transferringby landsliding or through rivers. By providing an integrated measurement of masses, gravimetry might thus becomplementary to common methods used to assess the sediments discharge of rivers. But the masses of rocksdisplaced by Morakot were exceptionally large as a result of the record-breaking rainfalls brought by this typhoonand one might wonder to what extent time-lapse gravimetry could record such sediment transfers. In order tobetter assess the capabilities of this method, we set a time-lapse gravity network dedicated to the monitoring ofsuch sediments transfers in Paolai village (south-central Taiwan). Paolai is located near the large Laonong riverwhere temporary alluvial deposits of sediments exist and face steep mountain slopes likely to experience landslides.Both features are considered as potential source of mass transfers, and in turn of temporal gravity changes. Thefirst base gravity measurements were done in November 2015, using absolute and relative gravimeters, and will berepeated every year, before and after the typhoon season. In the same time, we also use a terrestrial lidar to scan thegeometry of both the river and the mountain slopes, hence providing a detailed topographical survey of the studiedarea. Adding Lidar measurements is an efficient strategy to solve for the non-uniqueness of gravity solutions.Meanwhile, we use the Eros morphodynamic model, that combine landsliding and flooding models, to investigatevarious scenarios of landsliding and subsequent sediment transport and compute the gravity changes on a virtualnetwork of gravimeters. This gives us insights on the expected order of magnitudes for these surface sedimenttransfers, which are useful to unravel the induced gravity signal from others sources such as local hydrology orvertical ground displacements. The modeling results also enable us to set network location that are best defined todetect mass changes associated with sediment transfer. The main objective of this study is to test whether timelapsegravity brings a new and reliable information compared to present methods monitoring sediments transfersand landscape evolution.
European Geosciences Union General Assembly 2016
Vienne, Austria

insu-01308554
https://hal-insu.archives-ouvertes.fr/insu-01308554

Éditeur(s) : HAL CCSD
Résumé : International audience
A key issue for any project that aims to study endangered animals is the counting process. In this work, we propose an algorithm for automatic counting of singing birds in their habitat by using wireless sensors fitted with microphone. Sensors are used to record audio samples of bird songs and samples are analyzed to extract fingerprints that permit to recognize bird species. This paper details the counting algorithm that uses graph theory and audio inputs comparison. Finally, we demonstrate our scheme efficiency through experimentations.
International Symposium on a World of Wireless, Mobile and Multimedia Networks
Lucca, Italy

hal-00618563
https://hal.archives-ouvertes.fr/hal-00618563
DOI : 10.1109/WoWMoM.2011.5986215

Éditeur(s) : HAL CCSD ACM
Résumé : International audience
This study presents two algorithms that count birds with wireless sensors equipped with microphones. Audio inputs are parametrized to get some kind of fingerprints which are used to recognize the song of the birds in a classification process. Afterward, counting algorithms derive an estimate of the number of singing birds in the habitat. Unlike traditional approaches which leverage the audio waveform to get the location of the targets, we use a trilateration technique on graphs derived from the detection of the birds. These graphs exhibit nice properties which enable the finding of the estimate in polynomial time. Further, experiments are conducted and confirmm the efficiency of our counting algorithms even in the presence of noise.
Proceedings of the 6th ACM symposium on Performance evaluation of wireless ad hoc, sensor, and ubiquitous networks
New York, United States

hal-00602263
https://hal.archives-ouvertes.fr/hal-00602263
DOI : 10.1145/1641876.1641891

Éditeur(s) : Elsevier Science Bv
Résumé : We developed a growth model for Crassostrea gigas oyster shells based on the use of in situ temporal manganese markings to calibrate natural cathodoluminescence (CL) changes in the shell hinge sections. A 30 min to 4-h exposure period with Mn2+ (90-120 mg l(-1)) was sufficient to create a detectable mark in the shells. This makes the Mn2+ markings the fastest mollusc shells marking technique to date. The natural CL from juvenile and adult shells cultured in four standard shellfish-farming locations along the English Channel and French Atlantic coasts, exhibited a seasonal pattern (maximum CL intensity occurring during summer periods, minimum CL intensity occurring during winter). Hydrobiological data recorded at Baie des Veys site allows us to attribute the seawater temperature as the main parameter controlling CL of shells. Chlorophyll a and seawater manganese concentration were not decisive in the luminescence intensity of the shells. A relationship between oyster hinge growth and the length of shells makes the umbo investigations a promising tool for oyster-farming and/or wild stock assessments. Shell growth varied at spatial and temporal scales (higher growth rates were observed during summer-autumn and lower during the winter period), depending on seawater temperature changes. Sub-monthly Mn2+ markings support the fact that shell deposition can occur under temperatures below 6 degrees C, which has to be taken into account for both shellfish production and environmental monitoring derived from chemical compositions of the shells. Finally, our results point out the efficiency of age and shell growth rate determination by CL analysis in further shellfish ecosystem researches.
Aquaculture (0044-8486) (Elsevier Science Bv), 2010-02 , Vol. 300 , N. 1-4 , P. 206-217

Droits : 2010 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00002/11300/7912.pdf
DOI:10.1016/j.aquaculture.2009.12.018
http://archimer.ifremer.fr/doc/00002/11300/

Éditeur(s) : HAL CCSD
Résumé : International audience
In the context of climate change, this study presents the ability of major/trace elements together with strontiumisotopes to trace back water paths at small scale and to deconvolve the geochemical signal of a small watershedsubject to intense flash floods episodes (Peyne, Hérault, France). Two small sub-basins draining distinct lithologiesin their heads (Plio-Villafranchian conglomerate versus Triassic gypsum-rich marls and dolomites) and the sameMiocene lithology downstream are investigated.Major elements and Ca/Na vs. Mg/Na ratios classically applied at large scale to distinguish carbonate from silicateweathering, allow here discriminating the three main lithologies from the two sub-basins. Trace elements Rband Sr coupled to calcium, also allow this lithological discrimination but in addition the Ca/Rb vs. Sr/Rb tracersappear to be much more discriminant for the various hydrological conditions. Thus, in combination with detailedlithological descriptions, they allow identifying the different facies that imprint the water signature through water-rock interaction according to the hydrological conditions.Strontium isotopes and Rb/Sr ratio, discriminate more precisely the drained lithologies of the 2 sub-basins. Firstly,the 87Sr/86Sr ratios allow identifying the nature of the lithologies and their main component(s) contributing to theSr budget in water and thus imprint the isotopic signature. Secondly, Sr isotopes evidenced two distinct Miocenefacies: the detritric faction (sandy marls), and the marine carbonates.The geochemical signatures of the brook samples draining both compartments were compared to the signatureof the Peyne River outlet just before the confluence into the Hérault River. It appears that the signature of thePeyne River, integrating all the water draining the basin, is relatively stable whatever the hydrological conditionsand mainly marked by the Miocene formations. Sr isotopes further highlight that this signature seems to resultfrom the mixing of both Miocene facies present in the lower part of the Peyne watershed, i.e. the sandy marls andthe carbonates. The typical signatures of the Plio-Villafanchian conglomerates and Triassic gypsiferous marls anddolomites of the headwaters of each sub-basin are completely hidden by the Miocene signatures. This should berelated to the large drainage area of the Miocene compared to other lithologies, despite the high solubility of thegypsum formations releasing large quantities of dissolved elements in solution.Understanding water paths at small scale is even more efficient when the geochemical approach is coupled with adetailed geological description. Indeed, the geochemical tracers are extremely dependent on the facies sequences(morphology) and of the soil nature (mineralogical composition), this is particularly sensitive at small scale.In the context of climate change increasing the intensity of rain events in the Mediterranean region, and resultingin catastrophic floods events (flash floods), tracing the origin of water contributing to the runoff is of primaryimportance and this must be investigated at small scale. Geochemical and isotopic fingerprinting thus constituteexcellent tools which can help to define the area of interest to be monitored in the framework of flood forecast andwarning networks
EGU General Assembly 2015
Vienne, Austria

hal-01118622
https://hal-brgm.archives-ouvertes.fr/hal-01118622

Éditeur(s) : HAL CCSD
Résumé : Coral reefs are amongst the richest and more emblematic ecosystems of the world. These hotspots of biodiversity provide many services to Human societies, bringing leisure and economic added values. In many areas, especially developing countries, these ecosystems are submitted to both climate change (rise of sea temperature and level, acidification) and human coastal pressures (urbanisation, resources exploitation). In this context, an increasing number of Marine Protected Areas is settled on coral reefs environments in order to ensure their conservation and to mitigate local pressures. Hence, one of MPAs Managers' missions is to bring ecological and social data together to build integrated indicators of effectiveness. In Reunion Island, a MPA called the Marine reserve of La Réunion was settled in 2007 along a densely urbanised and populated fringing reef coast. In order to better evaluate its MPA effectiveness, the manager requires the integration of social stakes to the management plan. A uses monitoring protocol was developed in this purpose using an ultra light aircraft and a camera. Data on 15 different recreational and non-recreational uses were acquired between 2010 and 2013, flying 48 times a year, and entered into a Geographic Information System. A huge resulting database allowed the building of an initial knowledge of the spatio-temporal distribution of uses within the Reserve. It also enabled the analysis of the uses' evolution regarding various factors of variations (amenities, facilities, shark attacks, tourism, etc.). Finally, we assessed the contribution to management efficiency using social indicators (governance, pressure indicators), and to interdisciplinary research in bringing ecologic and uses data together. This thesis brings a brand new information about coastal human activity and spatio-temporal dynamics of direct pressures on reef. This tool, designed to be reproducible and cost-optimized, enables the production of a set of indicators. Its integration to the management plan exclusively depends on the strategic choices of the manager.
Les récifs coralliens figurent parmi les biomes côtiers les plus emblématiques de la planète. Ces points chauds de la biodiversité mondiale sont convoités par les sociétés humaines pour leurs qualités paysagères et leur plus-value économique. Exposés au même titre que de nombreux écosystèmes côtiers aux changements climatiques (élévation de la température, acidification des océans), ils sont de toutes parts soumis à une anthropisation littorale mal maitrisée (urbanisation, surexploitation des ressources). Dans ce contexte, de plus en plus d' Aires Marines Protégées (AMP) s'établissent sur des écosystèmes anthropisés, les amenant à intégrer l'Homme au coeur de la gestion. À La Réunion où l'urbanisation littorale est dense et où le paysage des usages littoraux ne cesse de s’étoffer, une Réserve Naturelle Marine (RNMR) a été établie en 2007 sur un récif frangeant. L’évaluation de l’efficacité de cette AMP par son gestionnaire doit se faire par le biais d'un ensemble d'indicateurs écologiques et socio-économiques. C’est en vue d’apporter des connaissances sur la fréquentation et les usages pratiqués au sein de la RNMR que cette thèse a été initiée. Elaboré sur la base d'un suivi en ULM, un protocole a été reproduit chaque année entre 2010 et 2013 et a permis la constitution d'une base de données spatialisée, dont l'exploitation a produit trois types de résultats: i) une connaissance initiale de la répartition spatio-temporelle des usages au sein de la RNMR; ii) une compréhension de l'évolution des dynamiques spatio-temporelles à la lumière des facteurs de variations identifiés (aménagements, aménités, crise requin, tourisme, etc.), et iii) une contribution à la gestion par le développement d'indicateurs sociaux (gouvernance, pressions), et à la recherche interdisciplinaire par une confrontation des données de fréquentation et des données écologiques du milieu. La réflexion menée dans le cadre de cette thèse apporte un éclairage nouveau sur les usages et la fréquentation des littoraux coralliens à La Réunion, et leur traduction en termes de pression anthropique directe. Pensé pour être reproductible et optimisé en termes de coût, cet outil permet la production d’un ensemble d’indicateurs dont l’intégration au plan de gestion dépend exclusivement des choix stratégiques du gestionnaire.
https://tel.archives-ouvertes.fr/tel-01308703

Droits : http://creativecommons.org/licenses/by-nc-sa/
tel-01308703
https://tel.archives-ouvertes.fr/tel-01308703
https://tel.archives-ouvertes.fr/tel-01308703/document
https://tel.archives-ouvertes.fr/tel-01308703/file/Th%C3%A8se_Lemahieu.pdf