Éditeur(s) : HAL CCSD Paris : Muséum national d'histoire naturelle
Résumé : International audience
Coral reefs are one of the most diverse ecosystems on Earth and sustain millions of people worldwide.However, coral reefs are temporally dynamic and fragile systems subject to ever increasing disturbancesof anthoropogenic and natural origins. Understanding the patterns and trajectories of changes through time isurgently needed to estimate the resilience of coral reefs. To ascertain these patterns, we depend on the availabilityof long-term datasets, which are seldom available. In this study, we present the data set which allowed us to analysethe long-term trends of coral and fish assemblages for the island of Moorea (French Polynesia) from 1983to 2014, a dataset spanning 32 years, comprising two Acanthaster planci outbreaks (1987 and 2006) and severalhurricanes (1982, 1983, 1991 and 2010), on three permanent monitoring sites (quadrats of 50 × 2 m2) located onboth fringing and barrier reefs as well as on the outer slope. Coral cover oscillated significantly over time, particularlyon the outer slope where it suffered greatly from the effects of A. planci outbreaks and hurricanes. Totalfish and commercial fish abundances varied significantly across the three habitats. Prior to 2000, both total fishand herbivorous fish abundances increased on the barrier reef while after this time, numbers began to drop significantlyalong the outer slope. Species richness for total, commercialized and herbivorous fish increased over thesampling period for all three habitats. There were varied responses amongst species to disturbances on the outerslope over the sampling period: while some tended to disappear for a while before reappearing, others showed apeak in abundance in the middle of the sampling period, and still others increased or decreased continuously orwere stable over time. Our results support the view that coral reefs are highly dynamic systems and that differentfunctional groups show different temporal trajectories. While disturbance is probably the major driver for coralcover dynamics, its impact is less obvious for fish, possibly due to their mobility and population dynamics whichmay mask the effect of disturbance.
Les récifs coralliens sont des systèmes dynamiques et diversifiés régulièrement soumis à des perturbationsnaturelles et anthropiques, sources d’hétérogénéité spatiale et temporelle dans la structure et la dynamique deces communautés d’organismes que sont, entre autres, les poissons et les coraux. Récemment, il a été démontréque les activités humaines pouvaient modifier les régimes naturels de perturbations des récifs coralliens en transformantles événements ponctuels en perturbations persistantes ou en stress chronique, soit en introduisant denouveaux types de perturbations, soit en ajoutant ou altérant certaines perturbations naturelles nécessaires au bonmaintien de la dynamique inhérente aux récifs. Dans cette étude, nous présentons la base de données qui nouspermettra d’analyser les tendances à long-terme des assemblages de poissons et de coraux de l’île de Moorea(Polynésie française) entre 1983 et 2014 sur une période de 32 ans, comprenant deux proliférations d’Acanthasterplanci (1987 et 2006) et plusieurs cyclones (1982, 1983, 1991 et 2010), sur trois sites de suivi permanents(quadrats de 50 × 2 m2) sur les récifs barrière et frangeant ainsi que sur la pente externe. La couverture corallienneprésente de fortes oscillations, en particulier sur la pente externe où elle a répondu fortement à la proliférationd’A. planci et des cyclones. Les abondances des poissons totaux et des poissons commercialisés montrent destendances contrastées sur les trois habitats, avec, plus particulièrement, une augmentation sur le récif barrière etune diminution sur la pente externe après 2000. Ces tendances se retrouvent chez les poissons herbivores dansces deux habitats. La richesse spécifique des poissons totaux, commerciaux et herbivores, augmente de façoncontinue au cours de la période d’étude dans les trois habitats. Des groupes particuliers d’espèces répondentdifféremment aux perturbations de la pente externe au cours du suivi : alors que certaines espèces ont tendanceà disparaître pendant quelques années avant de réapparaître, d’autres présentent un pic en terme d’abondanceen milieu de suivi ; d’autres espèces ont des abondances qui augmentent ou diminuent de façon continue, etd’autres encore montrent des abondances stables. Ceci indique que les récifs coralliens sont des systèmes trèsdynamiques dans lesquels les perturbations naturelles peuvent affecter les espèces de façon différente. Alors quele régime de perturbations naturelles semble être important pour la dynamique de la couverture corallienne danscertains habitats, cela se retrouve beaucoup moins pour les poissons. Cette atténuation des fluctuations spatialeset temporelles peut être due aux aptitudes de dispersion de nombreuses espèces de poissons, capables de chercherun autre habitat favorable en cas de perturbation de l’habitat corallien d’origine.
ISSN: 0399-0974

hal-01282378
https://hal-univ-perp.archives-ouvertes.fr/hal-01282378

Éditeur(s) : HAL CCSD
Résumé : Both short-term and long-term morphodynamics of sand barrier systems forced by moderate storm conditions have been studied significantly in the literature. However, the dynamics of the emerged beach -- from a seaside water depth of ~ 1.5 metres below the lowest tide to the back-barrier -- impacted by typhoons remain scarcely documented. This study focuses on the analysis and a better understanding of the morphologic changes of such an emerged beach, when it is forced by one typhoon, several typhoons or the combination of a summer season of typhoons and a winter season of Monsoon wave/ wind conditions. The monitoring of near-shore hydrodynamics and beach morphodynamics was performed in the Wan-Tzu-Liao sand barrier from November 2011 to August 2012. Waves, currents and water level were measured at an offshore buoy (Cigu buoy; 18 m of water depth; 1.5 km seaward the studied zone), a current profiler (4 m of water depth), and a serie of pressure sensors deployed along a cross-shore section from the lower intertidal zone up to the eolian dune. Tide was obtained from a tide gauge inside the lagoon and wind conditions were obtained respectively from an inland station and the offshore Cigu buoy. Morphodynamic changes were monitoring thanks to DGDPS surveys performed on a grid including a 300 meters long portion of sand barrier extending from the subtidal zone to the back-barrier, as well as along two cross-shore and two long-shore profiles located within the grid. Surveys were performed each week during winter and just before and after each storm during the typhoons summer season. This field methodology provided a new and very robust dataset in order to quantify sand barrier dynamics exposed to high-energy events at various time scales. Amongst the eight typhoons recorded, TALIM is the most significant and representative. Offshore wave height reached 10.34 m (Tp = 14.6 s) at Cigu buoy and 2.3 m in 4 m of water depth. Morphological changes recorded 6 m of retreat for the dune front, a 20 m large dune breaching and the occurence of a wash-over fan in the lagoon. These changes form a well-known morphodynamic responses to moderate storms. More surprisingly, TALIM drove a significant nourishment of the supratidal zone, as well as a positive sand balance on the whole sand barrier. Five other typhoons resulted in the same type of morphological responses while two typhoons resulted in a strong erosion of the whole emerged beach. During winter and spring (moderate wave conditions and strong Monsoon winds), sand moved from the beach front to the back-barrier. For the whole year, the sand barrier recorded a 12 m landward migration concomitantly with a 12 m widening without abrasion of the dune elevation.
American Geophysical Union, Fall Meeting 2013

hal-01012312
https://hal.archives-ouvertes.fr/hal-01012312

Éditeur(s) : HAL CCSD EDP Sciences
Résumé : International audience
In order to ensure a sustainable management of reef fisheries, data need to be collected regularly on the effect of these fisheries on both fish resources and the ecosystems that sustain them. Habitat and resources monitoring programs can provide such information, but are difficult to implement as they involve a range of technical, financial and human resources. Regarding these problems, the involvement of the local population in monitoring programs, called participatory monitoring, seems to offer solutions. Indeed, participatory monitoring has the potential of increasing the number of data collected at low cost, while taking advantage of the traditional ecological knowledge available locally. Some questions need clarifying, however: which methods can bring relevant information for the monitoring of reef fisheries while being appropriate to the motivations and skills of the local population? Is the degree of participation of the local population sufficient to make the monitoring program work, particularly over the long term? To answer these questions, participatory monitoring methods commonly used for coral reef ecosystems have been implemented to assess reef fisheries at three different sites: Moorea island and Tikehau atoll in French Polynesia, and the Bay of Tulear in Madagascar. While highlighting the relevance of some participatory monitoring programs for snapshot and large-scale surveys, the results of this study also show their lesser interest for regular data gathering on long-time scales. In any case, strong coordination and supervision by scientists are considered essential.
La gestion durable des écosystèmes coralliens nécessite de disposer d’informations régulières concernant l’impact des pêcheries sur les ressources récifales et sur les écosystèmes dont elles dépendent. Les suivis intégrés des ressources, des habitats et des espèces associées qui visent à fournir ce type d’informations sont difficiles à mettre en œuvre, car ils impliquent de nombreuses ressources humaines, techniques et financières. Face à ces problèmes, la participation de la société civile dans les programmes de suivi semble en mesure d’apporter des solutions. Dans le but de tester cette hypothèse, des méthodes de suivi participatif ont été mises en œuvre afin de caractériser des pêcheries récifales sur trois socio-écosystèmes contrastés : l’île de Moorea et l’atoll de Tikehau en Polynésie française, et le littoral de Tuléar à Madagascar. Les résultats de cette étude soulignent la pertinence de certains suivis participatifs pour fournir une vision écosystémique dans le cas de collecte de données ponctuelles et de large envergure, et leur intérêt moindre pour la collecte continue de données sur de longues échelles de temps. Dans tous les cas, une structure de coordination et l’implication de scientifiques s’avèrent primordiales pour assurer pérennité et fiabilité au système de suivi.
ISSN: 1240-1307

hal-01302983
https://hal-univ-perp.archives-ouvertes.fr/hal-01302983
DOI : 10.1051/nss/2013109

Éditeur(s) : HAL CCSD American Association for the Advancement of Science
Résumé :  
Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 × 1015 to 1.6 × 1015 grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change.
ISSN: 0036-8075

hal-01032111
https://hal.archives-ouvertes.fr/hal-01032111
DOI : 10.1126/science.1164033

Éditeur(s) : Pergamon-elsevier Science Ltd
Résumé : Society's needs for a network of in situ ocean observing systems cross many areas of earth and marine science. Here we review the science themes that benefit from data supplied from ocean observatories. Understanding from existing studies is fragmented to the extent that it lacks the coherent long-term monitoring needed to address questions at the scales essential to understand climate change and improve geo-hazard early warning. Data sets from the deep sea are particularly rare with long-term data available from only a few locations worldwide. These science areas have impacts on societal health and well-being and our awareness of ocean function in a shifting climate. Substantial efforts are underway to realise a network of open-ocean observatories around European Seas that will operate over multiple decades. Some systems are already collecting high-resolution data from surface, water column, seafloor, and sub-seafloor sensors linked to shore by satellite or cable connection in real or near-real time, along with samples and other data collected in a delayed mode. We expect that such observatories will contribute to answering major ocean science questions including: How can monitoring of factors such as seismic activity, pore fluid chemistry and pressure, and gas hydrate stability improve seismic, slope failure, and tsunami warning? What aspects of physical oceanography, biogeochemical cycling, and ecosystems will be most sensitive to climatic and anthropogenic change? What are natural versus anthropogenic changes? Most fundamentally, how are marine processes that occur at differing scales related? The development of ocean observatories provides a substantial opportunity for ocean science to evolve in Europe. Here we also describe some basic attributes of network design. Observatory networks provide the means to coordinate and integrate the collection of standardised data capable of bridging measurement scales across a dispersed area in European Seas adding needed certainty to estimates of future oceanic conditions. Observatory data can be analysed along with other data such as those from satellites, drifting floats, autonomous underwater vehicles, model analysis, and the known distribution and abundances of marine fauna in order to address some of the questions posed above. Standardised methods for information management are also becoming established to ensure better accessibility and traceability of these data sets and ultimately to increase their use for societal benefit. The connection of ocean observatory effort into larger frameworks including the Global Earth Observation System of Systems (GEOSS) and the Global Monitoring of Environment and Security (GMES) is integral to its success. It is in a greater integrated framework that the full potential of the component systems will be realised. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.
Progress In Oceanography (0079-6611) (Pergamon-elsevier Science Ltd), 2011-10 , Vol. 91 , N. 1 , P. 1-33

Droits : 2011 Published by Elsevier Ltd. All rights reserved.
http://archimer.ifremer.fr/doc/00044/15557/15923.pdf
DOI:10.1016/j.pocean.2011.05.001
http://archimer.ifremer.fr/doc/00044/15557/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Grey (Halichoerus grypus) and harbour seals (Phoca vitulina) are sympatric seal species, but they display distinct strategies of habitat use and connectivity between haulout sites. The distribution patterns and variations in relative abundance of both species were investigated along the French coast of the English Channel, at the southern limit of their range where seal numbers are increasing. Regular censuses conducted at all main haulout sites in mainland France showed significant seasonal variations at most sites, with more harbour seals counted during summer (breeding and moulting seasons), and more grey seals during summer only in the eastern English Channel. Trends in maximum haulout numbers at haulout sites showed a significant increase over the last five years, ranging from 9.7 to 30.9% per year for harbour seals, and from 5.8% (in the western English Channel) to 49.2% (in the eastern English Channel) per year for grey seals. These rates of increase in grey seal numbers are not linked to local pup production and most probably result from seal movements from the southwest British Isles and the North Sea, respectively. Aerial surveys conducted across the English Channel showed that most seal observations at sea were concentrated in the north-eastern English Channel. Telemetry showed that the 28 harbour seals tracked remained highly coastal, within a radius of 100 km from their haulout sites, and did not move to other known colonies. Grey seals moved much greater distances, reaching up to 1200 km from their capture site. More than half of the 45 grey seals tracked crossed the English Channel, especially during the breeding season, moving to known colonies in the southwest British Isles and the North Sea. Combining individual tracks and long-term surveys of the seal populations allowed a better understanding of the dynamics of these populations and their connectivity at a larger regional scale. The findings provide direct information for the management of grey and harbour seals within the frame of the Marine Strategy Framework Directive, and highlight focus areas where potential interactions between the two species should be monitored.
ISSN: 0967-0645

hal-01509674
https://hal.archives-ouvertes.fr/hal-01509674
DOI : 10.1016/j.dsr2.2017.04.004

Éditeur(s) : Elsevier Science Bv
Résumé : The overexploitation of fishery resources has led to a major fisheries crisis. In this context, artisanal fisheries, and in particular small-scale coastal fisheries, appear as relevant alternatives for a sustainable use of coastal resources. Marine Protected Areas (MPA) are more and more used as management tools for these fisheries, as protection effects and targeted access regulations may benefit to commercial fishers. Managers and scientists need then quantitative information not only to adapt their management to the fishing activity present on their territory, but also to estimate the effects of MPA management on it. This study provides catch and effort estimates that are essential for appraising and managing the artisanal fishery in the Côte Bleue Marine Park (CBMP), a French Mediterranean MPA including two No-Take Zones of different age and size. A field protocol was defined and implemented between July 2009 and June 2010 within the CBMP. Seven métiers were identified and characterized by target species, gear type, fishing grounds and fishing periods. During the one-year studied period, 3512 fishing trips and 4645 fishing operations were performed by 30 active boats in the Côte Bleue fishing territory, amounting to 9500 km of immersed nets. In total, approximately 130 tons of catch were landed in the six CBMP harbors, out of which 58% depend on the three main species caught on the Côte Bleue: hake (Merluccius merluccius), gilthead seabream (Sparus aurata) and common sole (Solea solea). The presented methodology could be part of a long term monitoring requiring close collaboration with local fishers. It enables adaptive management with respect to changes in fishing pressure (from inside and outside the MPA) that may impact the environment and its resources.
Fisheries Research (0165-7836) (Elsevier Science Bv), 2014-06 , Vol. 154 , P. 93-101

Droits : 2014 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00180/29120/29367.pdf
DOI:10.1016/j.fishres.2014.02.006
http://archimer.ifremer.fr/doc/00180/29120/

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
The life-history traits and population dynamics of species are increasingly being attributed to the characteristics of their preferred habitats. While coral reef fish are often strongly associated with particular habitats, long-term studies establishing the demographic and life-history consequences of occupying different reef substrata are rare and no studies have monitored individuals in situ over their lifetime and determined the fate of their offspring. Here, we documented a quasi-turnover and local reproductive success for an entire population of orange clownfish (Amphiprion percula) from Kimbe Island, Papua New Guinea, by taking bi-annual samples of DNA over a 10-yr period (2003–2013). We compared demographic and life-history traits of individuals living on two host anemone species, Heteractis magnifica and Stichodactyla gigantea, including female size, adult continued presence (a proxy for relative longevity range), early post-settlement growth, the number of eggs per clutch and ‘local’ reproductive success (defined for each adult as the number of offspring returning to the natal population). Our results indicate that while the relative longevity of adults was similar on both host anemone species, females living in H. magnifica were larger than females in S. gigantea. However, despite females growing larger and producing more eggs on H. magnifica, we found that local reproductive success was significantly higher for clownfish living in S. gigantea. Life-history traits also exhibited local spatial variation, with higher local reproductive success recorded for adults living on S. gigantea on the eastern side of the island. Our findings support a ‘silver-spoon’ hypothesis that predicts individuals that are fortunate enough to recruit into good habitat and location will be rewarded with higher long-term reproductive success and will make a disproportionate contribution to population renewal.
ISSN: 0722-4028

hal-01357939
https://hal-univ-perp.archives-ouvertes.fr/hal-01357939
DOI : 10.1007/s00338-016-1485-1

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Advances in groundwater storage monitoring are crucial for water resource management and hydrological processes understanding. The evaluation of water storage changes (WSC) often involve point measurements (observation wells, moisture probes, etc.), which may be inappropriate in heterogeneous media. Over the past few years, there has been an increasing interest in the use of gravimetry for hydrological studies. In the framework of the GHYRAF (Gravity and Hydrology inAfrica) project, 3 yr of repeated absolute gravity measurements using a FG5-type gravimeter have been undertaken at Nalohou, a Sudanian site in northern Benin. Hydrological data are collected within the long-term observing system AMMA-Catch. Once corrected for solid earth tides, ocean loading, air pressure effects, polar motion contribution and non-local hydrology, seasonal gravity variations reach up to 11 μGal, equivalent to a WSC of 260-mm thick infinite layer of water. Absolute temporal gravity data are compared to WSC deduced from neutron probe and water-table variations through a direct modelling approach. First, we use neutronic measurements available for the whole vertical profile where WSC occur (the vadose zone and a shallow unconfined aquifer). The RMSD between observed and modelled gravity variations is 1.61 μGal, which falls within the error bars of the absolute gravity data. Second, to acknowledge for the spatial variability of aquifer properties, we use a 2-D model for specific yield (Sy) derived from resistivity mapping and Magnetic Resonance Soundings (MRS). The latter provides a water content (θMRS) known to be higher than the specific yield. Hence, we scaled the 2-D model of θMRS with a single factor (α). WSC are calculated from water-table monitoring in the aquifer layer and neutronic measurements in the vadose layer. The value of α is obtained with aMonte-Carlo sampling approach, minimizing the RMSD between modelled and observed gravity variations. This leads to α = Sy/θMRS = 0.63 ± 0.15, close to what is found in the literature on the basis of pumping tests experiments, with a RMSD value of 0.94 μGal. This hydrogeophysical experiment is a first step towards the use of time-lapse gravity data as an integrative tool to monitor interannual WSC even in complicated subsurface distribution.
ISSN: 0956-540X

hal-00821181
https://hal.archives-ouvertes.fr/hal-00821181
DOI : 10.1093/gji/ggt146

Éditeur(s) : HAL CCSD
Résumé : 1 p.
For groundwater issues (potential leakages in waste repository, aquifer management ...), the development of modeling techniques is far ahead of the actual knowledge of aquifers. This raises two fundamental issues: 1) which and how much data are necessary to make predictions accurate enough for aquifer management issues; 2) which models remain relevant to describe the heterogeneity and complexity of geological systems. The French observatory H+ was created in 2002 with the twofold motivation of acquiring a large database for validating models of heterogeneous aquifers, and of surveying groundwater quality evolution in the context of environmental changes. H+ is a network of 4 sites (Ploemeur, Brittany, France; HES Poitiers, France; Cadarache, France; Campos, Mallorca, Spain) with different geological, climatic, and economic contexts. All of them are characterized by a highly heterogeneous structure (fractured crystalline basement for Ploemeur, karstified and fractured limestone for Poitiers, Cadarache and Mallorca), which is far to be taken into account by basic models. Ploemeur is exploited as a tap-water plant for a medium-size coastal city (15,000 inhabitants) for 20 years. Each site is developed for long term investigation and monitoring. They involves a dense network of boreholes, detailed geological and geophysical surveys, periodic campaigns and/or permanent measurements of groundwater flow, water chemistry, geophysical signals (including ground motions), climatic parameter, etc. Several large-scale flow experiments are scheduled per year to investigate the aquifer structure with combined geophysical, hydrogeological, and geochemical instruments. All this information is recorded in a database that has been developed to improve the sustainability and quality of data, and to be used as a collaborative tool for both site researchers and modelers. This project lasts now for 5 years. It is a short time to collect the amount of information necessary to apprehend the complexity of aquifers; but it is already enough to obtain a few important scientific results about the very nature of the flow heterogeneity, the origin and residence time of water elements, the kinetic of geochemical processes, etc. We have also developed new methods to investigate aquifers (in-situ flow measurements, flow experiment designs, groundwater dating, versatile in-situ probes, etc.). This experience aiming at building up long term knowledge appears extremely useful to address critical issues related to groundwater aquifers: the structure and occurrence of productive aquifer in crystalline basement, the assessment of aquifer protection area in the context of highly heterogeneous flow, the biochemical reactivity processes, the long term evolution of both water quantity and quality in the context of significant environmental changes, for instance.
AGU, Fall Meeting 2008
San Francisco, United States

insu-00375980
https://hal-insu.archives-ouvertes.fr/insu-00375980

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : International audience
Earth deformation is a multi-scale process ranging from seconds (seismic deformation) to millions of years (tectonic deformation). Bridging short- and long-term deformation and developing seismotectonic models has been a challenge in experimental tectonics for more than a century. Since the formulation of Reid's elastic rebound theory 100 years ago, laboratory mechanical models combining frictional and elastic elements have been used to study the dynamics of earthquakes. In the last decade, with the advent of high-resolution monitoring techniques and new rock analogue materials, laboratory earthquake experiments have evolved from simple spring-slider models to scaled analogue models. This evolution was accomplished by advances in seismology and geodesy along with relatively frequent occurrences of large earthquakes in the past decade. This coincidence has significantly increased the quality and quantity of relevant observations in nature and triggered a new understanding of earthquake dynamics. We review here the developments in analogue earthquake modelling with a focus on those seismotectonic scale models that are directly comparable to observational data on short to long timescales. We lay out the basics of analogue modelling, namely scaling, materials and monitoring, as applied in seismotectonic modelling. An overview of applications highlights the contributions of analogue earthquake models in bridging timescales of observations including earthquake statistics, rupture dynamics, ground motion, and seismic-cycle deformation up to seismotectonic evolution.
ISSN: 1869-9510

hal-01553120
https://hal.archives-ouvertes.fr/hal-01553120
https://hal.archives-ouvertes.fr/hal-01553120/document
https://hal.archives-ouvertes.fr/hal-01553120/file/rosenau2017.pdf
DOI : 10.5194/se-8-597-2017

Éditeur(s) : HAL CCSD Mary Ann Liebert
Résumé : International audience
Little information is available on the molecular epidemiologic profile of HIV-1 in French Guiana, the French department with the highest HIV/AIDS incidence. To follow the evolution of HIV-1 diversity, we carried out a molecular analysis of HIV-1 isolates from 305 treatment-naive patients between 2006 and 2012. Protease and reverse-transcriptase sequences were obtained for subtype characterization, polymorphism analysis, and identification of drug resistance mutations. Of 305 HIV-1 strains, 95.1% were subtype B viruses. The overall prevalence of transmitted drug-resistance mutations (TDRMs) was 4.6% (14/305), ranging from 1.9% to 7.1% depending on the year. This study shows a low level of HIV-1 genetic diversity and a moderate prevalence of TDRMs with no evidence of an increasing trend over the study period. Nevertheless, the strong genetic polymorphism observed on both genes may be of concern for long-term treatment of people living with HIV-1 and thus deserves continuous monitoring.
ISSN: 0889-2229

pasteur-01583613
https://hal-riip.archives-ouvertes.fr/pasteur-01583613
https://hal-riip.archives-ouvertes.fr/pasteur-01583613/document
https://hal-riip.archives-ouvertes.fr/pasteur-01583613/file/2016%20Darcissac%20et%20al.%20ARHR.pdf
DOI : 10.1089/aid.2016.0048

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We conducted a laser-equipped analog experiment aimed at quasi-continuously monitoring the growth of a dense population of normal faults in homogeneous conditions. To further understand the way geological faults progressively gain in slip and length as they accumulate more strain, we measured with great precision the incremental slip and length changes that the analog faults sustain as they grow. These measurements show that the analog faults share common features with the natural ones. In particular, during their growth, the faults develop and maintain cumulative slip profiles that are generally triangular and asymmetric. The growth takes place through two distinct phases: an initial, short period of rapid lateral lengthening, followed by a longer phase of slip accumulation with little or no lengthening. The incremental slip is found to be highly variable in both space (along the faults) and time, resulting in variable slip rates. In particular, ‘short- and long-term' slip rates are markedly different. We also find that slip measurements at local points on fault traces do not contain clear information on the slip increment repeat mode. Finally, while the fault growth process is highly heterogeneous when considered at the scale of a few slip events, it appears homogeneous and self-similar at longer time scales which integrate many slip increments. This is likely to be the result of a feedback between stress heterogeneities and slip development. The long-term scale homogeneity also implies that the long-term faulting process is primarily insensitive to the short-term heterogeneities that are rapidly smoothed or redistributed. We propose a new conceptual scenario of fault growth that integrates the above observations and we suggest that faults grow in a bimodal way as a result of a self-driven and self-sustaining process.
ISSN: 0012-821X

Droits : info:eu-repo/semantics/OpenAccess
insu-00351998
https://hal-insu.archives-ouvertes.fr/insu-00351998
https://hal-insu.archives-ouvertes.fr/insu-00351998/document
https://hal-insu.archives-ouvertes.fr/insu-00351998/file/SchlagenhaufEtAl2008_EPSL_author.pdf
DOI : 10.1016/j.epsl.2008.06.042

Éditeur(s) : HAL CCSD
Résumé : International audience
The challenge is to implement research that can estimate the consequences ofclimate changes in terms of impact on terrestrial environments and resources.Emphasis should be placed on regions dependent on natural resources and forwhich demographic pressure is strong. Simulations obtained from climate modelprojections (using different Representative Concentration Pathways (RCPs))predict that the Mediterranean basin and its southern periphery are particularlyvulnerable to water resources and environmental impact (IPCC, AR5, 2013).An annual rainfall decrease by 30% is found for the projection period 2070-2099(IPCC, AR5, 2013) associated with a decrease in water resources by 30 to 50%(Milano, 2012). In addition, several studies using regional atmospheric modelsindicate an increase in the precipitation inter-annual variability with extremeevents and a spatial heterogeneous signature, superimposed on a decrease in thetotal precipitation amount (Giorgi and Lionello, 2008; Raible et al. 2010).Currently, regional climate projections are highly sensitive to the climate modelused. In particular, spatial resolution as well as local climate conditions seemto impact significantly on the simulations (Jacob et al. 2014).The Mediterranean region, at the interface between arid and temperate climateswith several mountainous areas, is a complex climate system affected by theinteractions between mid-latitude and sub-tropical processes. In this context,Morocco, located at the transition between a temperate climate to the North anda tropical climate to the south constitutes a key area for an impact and sensitivitystudy to global climate changes. The climate is influenced by the Atlantic Ocean,the Mediterranean Sea and the Sahara, together with a very steep orography inthe Atlas region. The precipitation distribution is therefore characterised by greatspatial variability, and exhibits a marked seasonality, a strong inter-annualvariability (Ouda et al. 2005) and in general a pronounced gradient from northto south and west to east. At a broader scale, Morocco is located on the subtropicalsubsidence path and between the Acores High and the Saharan Low (Agoussine,2003). Several studies have also identified strong links with inter-annualprecipitation variability and NAO index (Knippertz, 2003) as well as remoteclimate modes (Esper et al. 2007).Continental climate variability at a local/regional scale, if it is to be integratedin climate predictions, needs to be supported by long-term observation.Meteorological stations in Morocco provide climatic data mainly for the last40 years with only a few stations located in the mountainous region (Tramblayet al. 2012; 2013; Driouech et al. 2010). This climate database is also supportedby the IAEA network providing stations for which isotope tracers have beenapplied to daily/monthly rain and water vapour samples over 2 to 3 years between2000 and 2004. Besides the poor coverage of instrumented areas, lacustrinesystems can provide a climatic data set that offers access to short and long-termtime series of climate parameters when knowledge of modern lake water balanceis combined with lacustrine sedimentary-climate records. Lake sediment recordsideally provide high resolution climate/environmental information of the last10,000 years (Magny et al. 2013). This time interval (corresponding to theHolocene) is a key period to investigate short and long-term climate variabilityand to improve prediction in a warming climate.In this study we present an integrated approach focusing on a mountainous lake(Aguelmam Azigza). The modern lake system study is based on site monitoring(2012-2016) and available regional hydro-climatic data. These data show thatlake level changes during the instrumented period were mainly driven byprecipitation following the high inter-annual variability. These data are thencompared with accurately dated short sediment cores retrieved in the same lake.Micro-scale geochemical and sedimentological analyses of these sequencesenable us to identify various sedimentary facies that can be linked with periodsof high (low) lake levels over the past decades.
The Mediterranean Region under Climate ChangeLa méditerranée face au changement climatique

insu-01394690
https://hal-insu.archives-ouvertes.fr/insu-01394690
https://hal-insu.archives-ouvertes.fr/insu-01394690/document
https://hal-insu.archives-ouvertes.fr/insu-01394690/file/Vidaletal.2016-COP22-Chap1.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Yearly monitoring in one of the most affected coastal zones by the Prestige oil spill, namely Nemiña and O Rostro beaches (NW Spain), has been carried out since 2004. Topographic data of beaches revealed seasonal altimetric changes up to 4 m that would prevent the on shore persistence of oil. However, surficial and subsurficial oil was detected in the intertidal area of both beaches in all campaigns. The hydrocarbon analysis confirmed that this oil corresponded to the Prestige oil, even nine years after the accident. Tar balls were highly biodegraded suggesting that the oil was accumulated on the subtidal sediments for a long time and transported to the coast by the action of waves. The present work provides new evidence of the long term persistence of deep oil spills from wrecks in marine areas where the hydrodynamic conditions play a twofold key role, in determining the exposed coastal area to recurrent contamination and in burying and resurfacing the oil in the intertidal zone.
ISSN: 0304-3894

hal-01071707
https://hal.archives-ouvertes.fr/hal-01071707
DOI : 10.1016/j.jhazmat.2013.01.057

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : International audience
Determining the conditions under which populations may persist requires accurate estimates of demographic parameters, including immigration, local reproductive success, and mortality rates. In marine populations, empirical estimates of these parameters are rare, due at least in part to the pelagic dispersal stage common to most marine organisms. Here, we evaluate population persistence and turnover for a population of orange clownfish, Amphiprion percula, at Kimbe Island in Papua New Guinea. All fish in the population were sampled and genotyped on five occasions at 2-year intervals spanning eight years. The genetic data enabled estimates of reproductive success retained in the same population (reproductive success to self-recruitment), reproductive success exported to other subpopulations (reproductive success to local connectivity), and immigration and mortality rates of sub-adults and adults. Approximately 50% of the recruits were assigned to parents from the Kimbe Island population and this was stable through the sampling period. Stability in the proportion of local and immigrant settlers is likely due to: low annual mortality rates and stable egg production rates, and the short larval stages and sensory capacities of reef fish larvae. Biannual mortality rates ranged from 0.09 to 0.55 and varied significantly spatially. We used these data to parametrize a model that estimated the probability of the Kimbe Island population persisting in the absence of immigration. The Kimbe Island population was found to persist without significant immigration. Model results suggest the island population persists because the largest of the subpopulations are maintained due to having low mortality and high self-recruitment rates. Our results enable managers to appropriately target and scale actions to maximize persistence likelihood as disturbance frequencies increase.
ISSN: 0962-8452

hal-01239322
https://hal-univ-perp.archives-ouvertes.fr/hal-01239322
DOI : 10.1098/rspb.2015.1311

Éditeur(s) : Inter-Research
Résumé : We studied the foraging rhythms of green sea turtles Chelonia mydas on the seagrass beds of N'Gouja Bay, Mayotte Island (Comoros Archipelago) with acoustic transmitters and moored listening stations. We monitored 8 tagged turtles (4 probable males, 3 probable females and 1 immature), from 70 to 109 cm curved carapace length (CCL), for durations ranging from 5 to 92 d. The turtles exhibited a regular diel pattern: they foraged mainly during the day (on average 87% of seagrass detections were between 06:00 and 18:00 h) and rested on the inner reef slope during the night. Night time feeding activities were observed on the seagrass bed when the night light was high. The presence of turtles on the seagrass bed at night was significantly correlated with a night light index (r = 0.54, p = 0.002), which included both moon light and cloudiness indices. Behaviour of the only immature individual observed was similar to adult turtles, although it rested more frequently around noon. All turtles displayed a high fidelity to 1 foraging site within the seagrass bed. Acoustic transmitters and permanent listening stations are an appropriate technique for long-term behavioural studies of turtles, with no human interaction with turtles during tracking, and represent a suitable technique to assess the possible effects of environmental changes or human activities upon green turtle behaviour.
Marine Ecology Progress Series (0171-8630) (Inter-Research), 2006 , Vol. 306 , P. 295-302

Droits : Inter-Research 2006
http://archimer.ifremer.fr/doc/2006/publication-3616.pdf
DOI:10.3354/meps306295
http://archimer.ifremer.fr/doc/00000/3616/

Éditeur(s) : ICES 2008 Annual Science Conference, 22-26 september 2008, HALIFAX, CANADA
Résumé : Since 2000, Ifremer has been implemented a Fisheries Information System (FIS), in strong collaboration with the DPMA (Direction of fisheries and aquaculture of the French Ministry of Agriculture and Fisheries). The FIS aims at building an operational and multidisciplinary monitoring network for scientific purposes, allowing a comprehensive view of fishery systems including their biological, technical, environmental and economical components. The objectives of the FIS are (i) to provide the specifications and methodologies for the collection, storage and processing of fisheries data, with the constant concern to harmonise all these procedures on a national scale, (ii) to improve data management system and access to data for a wide-spread public, and (iii) to produce and distribute relevant datasets, indicators and synthesis, for understanding and evaluation, including bio-economic diagnostics of the fisheries, and assessment of the short and long-term impacts of fisheries management scenario and measures. The FIS covers all the French fisheries, including overseas territories and small-scale fisheries, for which data are often hardly available or missing, whereas two thirds of the French vessels are less than 12 meters long. The challenge was to establish a statistical and an integrated approach supporting bio-ecological and economic issues. To further an integrated analysis of the fishery systems, the wide range kinds of data - including acoustic surveys, biological in-situ observations, environmental observations, as well as fishing statistics (landings and efforts) or economic data - are managed in a single data management system, based on an integrated relational data base with geographical facilities.

Droits : 2008 ICES
http://archimer.ifremer.fr/doc/00059/17002/14504.pdf
http://archimer.ifremer.fr/doc/00059/17002/

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : International audience
To forecast marine disease outbreaks as oceans warm requires new environmental surveillance tools. We describe an iterative process for developing these tools that combines research, development and deployment for suitable systems. The first step is to identify candidate host–pathogen systems. The 24 candidate systems we identified include sponges, corals, oysters, crustaceans, sea stars, fishes and sea grasses (among others). To illustrate the other steps, we present a case study of epizootic shell disease (ESD) in the American lobster. Increasing prevalence of ESD is a contributing factor to lobster fishery collapse in southern New England (SNE), raising concerns that disease prevalence will increase in the northern Gulf of Maine under climate change. The lowest maximum bottom temperature associated with ESD prevalence in SNE is 128C. Our seasonal outlook for 2015 and long-term projections show bottom temperatures greater than or equal to 128C may occur in this and coming years in the coastal bays of Maine. The tools presented will allow managers to target efforts to monitor the effects of ESD on fishery sustainability and will be iteratively refined. The approach and case example highlight that temperature-based surveillance tools can inform research, monitoring and management of emerging and continuing marine disease threats.
ISSN: 0080-4622

Droits : http://creativecommons.org/licenses/by/
hal-01282834
https://hal-univ-perp.archives-ouvertes.fr/hal-01282834
https://hal-univ-perp.archives-ouvertes.fr/hal-01282834/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01282834/file/20150208.full.pdf
DOI : 10.1098/rstb.2015.0208

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : In this paper we present the potential of a new compact superconducting gravimeter (GWR iGrav) designed for groundwater monitoring. At first, 3 yr of continuous gravity data are evaluated and the performance of the instrument is investigated. With repeated absolute gravity measurements using a Micro-g Lacoste FG5, the calibration factor (−894.8 nm s−2 V−1) and the long-term drift of this instrument (45 nm s−2 yr−1) are estimated for the first time with a high precision and found to be respectively constant and linear for this particular iGrav. The low noise level performance is found similar to those of previous superconducting gravimeters and leads to gravity residuals coherent with local hydrology. The iGrav is located in a fully instrumented hydrogeophysical observatory on the Durzon karstic basin (Larzac plateau, south of France). Rain gauges and a flux tower (evapo-transpiration measurements) are used to evaluate the groundwater mass balance at the local scale. Water mass balance demonstrates that the karst is only capacitive: all the rainwater is temporarily stored in the matrix and fast transfers to the spring through fractures are insignificant in this area. Moreover, the upper part of the karst around the observatory appears to be representative of slow transfer of the whole catchment. Indeed, slow transfer estimated on the site fully supports the low-flow discharge at the only spring which represents all groundwater outflows from the catchment. In the last part of the paper, reservoir models are used to characterize the water transfer and storage processes. Particular highlights are done on the advantages of continuous gravity data (compared to repeated campaigns) and on the importance of local accurate meteorological data to limit misinterpretation of the gravity observations. The results are complementary with previous studies at the basin scale and show a clear potential for continuous gravity time-series assimilation in hydrological simulations, even on heterogeneous karstic systems.
ISSN: 0956-540X

hal-01526965
https://hal.archives-ouvertes.fr/hal-01526965
https://hal.archives-ouvertes.fr/hal-01526965/document
https://hal.archives-ouvertes.fr/hal-01526965/file/fores2016.pdf
DOI : 10.1093/gji/ggw396