Éditeur(s) : HAL CCSD American Physical Society
Résumé : International audience
We investigate a class of granular materials characterized by the possibility of interlocking between the particles. The interlocking is modeled by its effect through rolling resistance depending on relative rotation and normal force at the contact points and involving a single parameter analogous to the sliding friction coefficient. The model, which is introduced in the framework of the contact dynamics, method, is applied to simulate the simple shear of a large granular sample. We present a detailed analysis regarding the influence of rolling and sliding friction parameters on the macroscopic response in terms of shear strength, fabric properties, and force transmission. Interestingly, two distinct regimes can be distinguished in which the steady-state shear strength is controlled by either rolling resistance or sliding friction. The relative contributions of rolling and sliding contacts to the shear strength are consistent with the same two regimes. Interlocking strongly affects the force network by enhancing the arching effect and thus increasing the relative importance of weak contact forces and torques, which is reflected in a decreasing power-law probability distribution of the contact forces and torques below the mean. Due to the combined effect of friction and interlocking, the force-carrying backbone takes an increasingly columnar aspect involving a low fraction of particles. Our data suggest that the nature of the weak contact network is strongly affected by the formation of these columns of particles which do not need to be propped laterally. In particular, in the limit of high rolling resistance and sliding friction, the role of the weak network of contacts is no longer to prop the force chains, but, like the strong contact network, to actively sustain the deviatoric load imposed on the system.
ISSN: 1539-3755

hal-00412020
https://hal.archives-ouvertes.fr/hal-00412020
DOI : 10.1103/PhysRevE.78.021301

Éditeur(s) : HAL CCSD
Résumé : International audience
In many geological reservoirs, open fractures or fault zones generally induce high spatial variability of hydrodynamical properties and shape the main deep-seated flow paths. It is of crucial interest to determine their structure and properties in order to achieve a sound and sustained exploitation of resources or to estimate the risk of failure of any underground storage. Tiltmeters have emerged as new tools to observe deformation generated by groundwater flow. As such instruments are highly sensitive to pressure gradients, they are perfectly suited for monitoring channelized flow in connected fractures and fault zones. Hence, they provide a unique insight of these reservoirs' geometry and dynamics over broad time scales. Here we demonstrate that continuous tilt data from surface long baseline tiltmeters (LBT) can be used alone to evaluate the general functioning of a fractured hardrock system and estimate the hydraulic properties of its main conductive features. The study is applied to the pumping site of Ploemeur observatory (Brittany, France) which is well documented and instrumented, and therefore forms a convenient setting for introducing LBT as tools for fractured media hydrology. On the short term, tilt signals are strongly correlated with pumping cycles and associated head level changes in well-connected boreholes. Besides, when pumps are stopped the maximal tilt direction is systematically perpendicular to a subvertical fault zone whose azimuth of strike has thereby been refined down to degree precision. By using a semi-analytical model of deformation, we establish the link between tilt and pressure change during pumping interruptions which then allows for hydraulic properties estimation from tilt measurements only. Finally, we validate our results with previous estimates obtained from other studies and discuss the orientation of future work that could enhance these estimates.
AGU Fall Meeting 2014
San Francisco, United States

insu-01093437
https://hal-insu.archives-ouvertes.fr/insu-01093437

Éditeur(s) : HAL CCSD Elsevier
Résumé : Guadua sarcocarpa and Guadua weberbaueri (Poaceae: Bambuseae) have a negative influence on tree regeneration and recruitment in bamboo-dominated forests of southwestern Amazonia. The lack of advanced regeneration and sparse canopy in this forest type present a considerable challenge for developing sustainable timber management plans. We conducted field studies in the Porto Dias Agroextractive Settlement Project in Acre, Brazil to assess influences of logging in bamboo-dominated forest sites. Taxonomic composition, stand structure, aboveground biomass, commercial timber volume, and commercial tree seedling and bamboo culm density were compared between five logged vs. unlogged sites in different landholdings, using modified 0.5 ha Gentry plots. No differences in taxonomic composition, aboveground biomass, adult and juvenile stem density, or woody seedling and bamboo culm density were detected between paired logged and unlogged sites. Commercial timber volume, however, was reduced by almost two-thirds in logged plots, suggesting that long-term timber management goals in this forest type are compromised since so few future crop trees remained onsite. Our findings indicate that in order to maximize local management objectives, community forest managers must approach logging in bamboo-dominated forests with caution. We suggest an integration of non-timber forest product extraction with low harvest intensity and low-impact logging, tending of natural regeneration, and diversification of commercial species.
ISSN: 0378-1127

hal-01204213
https://hal.archives-ouvertes.fr/hal-01204213
DOI : 10.1016/j.foreco.2013.12.022
PRODINRA : 263103

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
Here, the first description of an epsilon sulfur-oxidizing bacterium from sulfide-rich sediments of marine mangrove in Caribbean is reported. According to TEM, this new strain contains intracytoplasmic large internal sulfur granules as confirmed by EDXS analyses performed using ESEM. The sulfur distribution obtained for this sulfur-oxidizing bacterial strain allows to conclude that elemental sulfur is formed as an intermediate oxidation product and stored intracellularly. According to conventional SEM observations, bacterial cells are ovoid, extremely motile by lophotrichous flagella. Phylogenetic analyses based on the analysis of partial sequence of 16S rDNA confirm that such bacterial strain belongs to the Thiovulum cluster and could be a representative of a new species in this poorly studied genus of sulfur-oxidizing free-living bacteria. Thus, reduced sediment of marine mangrove represents sulfide-rich environment sustaining development of both gamma and epsilon sulfur-oxidizing Proteobacteria
ISSN: 0378-1097

hal-01682113
https://hal.univ-antilles.fr/hal-01682113
DOI : 10.1093/femsle/fnx172

Éditeur(s) : HAL CCSD Lippincott, Williams & Wilkins
Résumé : International audience
OBJECTIVES: The ANRS-112 INTERPRIM trial assessed whether fixed-cycles of antiretroviral treatment interruption (ART-STI) combined or not with pegylated interferon alpha-2b (peg-IFN) could lower viral load and achieve a healthier immune system in patients diagnosed during primary HIV-1-infection (PHI). DESIGN AND METHODS: Patients were randomized to receive either continuous ART (cART) during 72 weeks, or cART during 36 weeks followed by three ART-STIs, or the same ART-STIs associated with peg-IFN during the first 14 weeks and each interruption (ART-STI-IFN). Treatment was stopped at week 72. Final evaluation was based on plasma HIV-RNA level 6 months after the last treatment interruption. RESULTS: Eighty-seven percent of patients achieved undetectable HIV-RNA at week 32, with no deleterious impact of sequential treatment interruptions (STIs). Viral rebounds during interruptions were lower in the ART-STI-IFN than in the ART-STI group and during the second and third interruptions compared with the first one. However, HIV-RNA levels, CD4 T-cell counts and CD4 T/CD8 T ratios were similar between groups after the 6-month interruption, with a persistent effect on CD4 T cells and total cell-associated HIV-DNA levels. Predictive factors of virological outcome were HIV-RNA and HIV-DNA levels at PHI and HIV-DNA levels at treatment interruption. HIV-specific responses did not differ between strategies and were not associated with outcome. Forty-eight percent of patients experienced treatment resumption during long-term follow-up without difference between groups. CONCLUSION: When initiated during PHI, STIs associated or not with IFN did not result in a different outcome as compared to cART. All regimens showed a high response rate and a sustained immunological benefit after cessation.
ISSN: 0269-9370

hal-00875175
https://hal.archives-ouvertes.fr/hal-00875175
DOI : 10.1097/QAD.0b013e32835844d9
PUBMED : 22842994

Éditeur(s) : HAL CCSD
Résumé : International audience
Semantic web standards, tools, ontologies and related technologies have considerably matured in the recent years. Nowadays, accessing a wide catalogue of biological, social, environmental, and ecological data sources helps stakeholders working on biodiversity to answer their complex questions. Will the real time access to web resources effectively support the definition of strategies to conserve and manage biodiversity? How might semantic web technologies help us to handle the complex and heterogeneous big data related to biodiversity? The workshop aims to identify the key challenges faced by the bioinformatics community, discuss potential solutions and identify the opportunities emerging from the trans-disciplinary interactions between Plant Science and Informatics experts. Therefore, we expect the bioinformatics experts to explain how they apply semantic web standards and tools to their scientific topic, from biology, agriculture, agro-ecology, genomics, environmental studies, to social sciences, citizen sciences. Research papers presenting various aspects of semantic web technologies applied to biodiversity data, ranging from position papers to implemented systems descriptions and their evaluation, will be selected. We are particularly interested in the use of the semantic technologies to design and develop systems that supports research on agricultural and wild biodiversity conservation and management for food security. Examples may include strategies for resilience to climate change pressures, sustainability of productive ecosystems, ecosystems services monitoring or territories management, rather than systems supporting only research on climate patterns or soil erosion.
http://hal-lirmm.ccsd.cnrs.fr/lirmm-00831757

lirmm-00831757
http://hal-lirmm.ccsd.cnrs.fr/lirmm-00831757
http://hal-lirmm.ccsd.cnrs.fr/lirmm-00831757/document

Éditeur(s) : HAL CCSD Université des Antilles
Résumé : International audience
In the past the Caribbean was restricted to offering elitist tourist activities, but over the last three decades it has to a large extent opened its doors to international tourism. The advent of mass tourism has been accompanied by a redistribution of the tourism functions and flows within the region. The significant growth in tourism, although essential to the economies of the Caribbean islands, has given rise to a number of issues, the first being the necessity to examine the multiplier effect from tourism revenue within these externally-dependent economies. Next there is both the question of access to resources and the closing of tourist sites in a context where local communities are focusing on coastlines to develop their own numerous tourism and recreational activities. These developments will inevitably require us to consider environmental issues and the sustainability of today’s predominant tourism activities.
Longtemps limité à des pratiques touristiques élitistes, l’espace caribéen s’est largement ouvert au tourisme international au cours des trois dernières décennies. L’avènement du tourisme de masse s’est accompagné d’une redistribution des flux et de fonctions touristiques dans cette région. Les enjeux, qui accompagnent l’importance croissante du fait touristique, essentiel pour les économies des îles caribéennes, sont de plusieurs ordres : tout d’abord, il convient de s’interroger sur les effets d’entraînement des revenus du tourisme dans le cadre de ces économies extraverties. Se pose également la question de l’accès aux ressources et de la fermeture des lieux touristiques, dans un contexte où les sociétés locales développent aussi leurs propres pratiques touristiques et récréatives ; autant d’usages qui se polarisent sur des ressources littorales et doivent nous interpeller sur les enjeux environnementaux et la durabilité des pratiques touristiques qui prévalent aujourd’hui.
ISSN: 1779-0980

hal-01624750
https://hal.archives-ouvertes.fr/hal-01624750
DOI : 10.4000/etudescaribeennes.4713

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Because earthworms sustain soil functioning and fertility, there is a need to advance the knowledge of their adaptation potential to chemicals in anthropogenic landscapes. Our hypothesis is that there is acclimation to organic chemicals (pesticides) in earthworms that durably persist under conventional farming in anthropogenic landscapes. The adaptation capability of two populations of earthworms (Aporectodea caliginosa) having a different chemical exposure history, - one originating from 20 years of organic farming (naïve population) and another from 20 years of conventional farming (pre-exposed population) - to cope with soil organic pollutant (Opus®, epoxiconazole a worldwide used fungicide) were investigated. Several complementary metabolic and energetic endpoints were followed, and cast production was assessed as a behavioural biomarker related to earthworms ecological role for the soil. Basal metabolism reflected by respiration rate was increased in both fungicide-exposed worms compared to controls. Glycogen resources were decreased in the same proportion in the two populations but more rapidly for the naïve (7 days) than for the pre-exposed population (28 days). Soluble protein and most amino-acids contents increased in the pre-exposed population only, suggesting a detoxification mechanism. Metabolomic profiles showed a cut-off between fungicide-exposed and control groups in the pre-exposed earthworms only, with an increase in most of the metabolites. Exposure to a low dose of epoxiconazole increased cast production of pre-exposed earthworms, and this resulted in an increase in pesticide disappearance. As far as we know, this is the first study which evidenced there is an acclimation to an agricultural chemical in earthworms derived from conventional farming that also relates to a change in their burrowing behaviour, and for which larger consequences for the soil ecosystem need to be addressed. This original finding is of major interest in the frame of ecosystem resilience to global changes. Whether this physiological adaptation is a general pattern of response against fungicides or other pesticides would need to be confirmed with other molecules and agricultural contexts.
Soil Biology and Biochemistry

hal-01005821
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01005821
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01005821/document
DOI : 10.1016/j.soilbio.2014.01.032

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : Understanding the ability of ecosystem processes to resist to and to recover from disturbances is critical to sustainable land use. However, the spatial variability of the stability has rarely been addressed. Here, we investigated the functional stability of a soil microbial process for 24 soils collected from adjacent locations from a 0.3 ha tropical rainforest plot in Paracou, French Guiana. The 24 locations were characterized regarding soil chemical and biological (microbial diversity) parameters and forest structure. The corresponding soils were submitted to an experimental transient heat disturbance during a microcosm experiment. The response of the respiration process was followed using substrate-induced respiration (SIR). The response of soil SIR to heat disturbance varied widely between samples. The variability of the SIR response increased just after the disturbance, and a global rather homogeneous decrease in SIR rates was observed 15 and 30 days after. The stability of SIR in response to heat disturbance could not be related to either the genetic or the metabolic diversity of the microbial community. The initial level of SIR before the disturbance was the soil variable that best correlated with the impact of the disturbance: the soil locations with the highest initial SIR rates were the most affected 15 and 30 days after the heat disturbance. Such a heterogeneous response suggests that the response of soil processes to a disturbance will be difficult to assess from only local-scale analyses and highlights the need for spatial explicitness in understanding biogeochemical processes.
ISSN: 1439-0108

hal-01204209
https://hal.archives-ouvertes.fr/hal-01204209
DOI : 10.1007/s11368-012-0528-7
PRODINRA : 214444

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : La mer des Caraïbes abrite une diversité de biotopes littoraux qui favorisent l’installation de trois écosystèmes - les récifs coralliens, les mangroves et les herbiers – riches et complexes. On y trouve également d’autres formations uniques tels les stromatolithes ou les trous bleus. Des conditions climatiques et océanographiques homogènes permettent à l’ensemble du bassin Caraïbe de constituer une unité sur les plans floristique et faunistique. Cette unité n’exclut pas une diversité biologique exceptionnelle avec notamment des espèces endémiques à la zone ; ce qui confère aux côtes des pays caribéens un intérêt écologique, paysager et scientifique certain. La reconnaissance sur le plan international et régional de l’importance de la Mer des Caraïbes mais aussi de sa fragilité a permis au milieu marin caribéen d’acquérir son statut de patrimoine naturel.En plus des services écosystémiques qu’elle rend (ressources halieutiques, protection des littoraux…), la Mer des Caraïbes constitue un atout indéniable dans le cadre du développement touristique de la zone aussi bien par le balnéaire que, plus récemment, par l’écotourisme. Ce dernier s’appuie généralement sur des aires marines protégées et doit permettre un développement durable des îles.A partir d’une étude de cas, le parc marin de Saba, l’objectif de cette étude est d’analyser les rapports entre patrimoine naturel marin et l’écotourisme, ainsi que les impacts économiques, sociaux et environnementaux de la mise en valeur de ces ressources.
The Caribbean Sea is home to a diversity of coastal habitats that support the installation of three rich and complex ecosystems - coral reefs, mangroves and seagrasses -. There are also other unique formations such as stromatolites or blue holes. Oceanographic and climatic conditions allow homogeneous throughout the Caribbean basin to form a unit in terms of flora and fauna. This unit does not exclude an exceptional biological diversity, including species endemic to the area, which give the coasts of the Caribbean countries an ecological, landscape and some science. Recognition on the international and regional importance of the Caribbean Sea but also its fragile marine environment has allowed the Caribbean to gain its status as a natural heritage.In addition to the ecosystem services it render (fisheries, coastal protection ...), the Caribbean Sea is a definite asset in the development of tourism in the area by the seaside as well as, more recently, ecotourism. The latter is generally based on marine protected areas and should facilitate the sustainable development of islands.From a case study, the Saba Marine Park, the objective of this study is to analyze the relationship between natural heritage and marine ecotourism, as well as economic, social and environmental development of these resources.
Saba

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.5487
http://journals.openedition.org/etudescaribeennes/5487

Éditeur(s) : HAL CCSD
Résumé : The mosquito species Aedes (Stegomyia) aegypti (Linnaeus 1762) was introduced into the Americas some 400 years ago from the African continent. Currently, this species is the primary agent behind dengue and chikungunya outbreaks in the pan-tropical area and its widespread distribution has likely played an important role in the recent expansion of the Zika virus. The biology of Ae. (Stg.) aegypti is particularly well known, which is not the case for its ecology. By adopting a cross-disciplinary approach I attempted to understand the relative contribution of biotic and abiotic factors as well as some evolutionary processes in the distribution of this species at the local and regional scales in French Guiana.Initially, I was interested in revising the core knowledge concerning the diversity of mosquitoes in French Guiana. By combining traditional and molecular taxonomy, this step allowed my colleagues and I to discover several new species and to create the appropriate tools to manage this type of entomological data.Secondly, we studied the spatio-temporal structure of resident aquatic macroinvertebrate communities in urban areas. This highlighted the existence of antagonistic and mutualistic interactions. In particular, the native mosquito Limatus durhamii Theobald 1901 appears to prevent the sustainable establishment of Ae. (Stg.) aegypti in slightly urbanized environments via a mechanism of competitive exclusion.
Le moustique Aedes (Stegomyia) aegypti (Linnaeus 1762) a été introduit dans les Amériques depuis le continent africain il y a environ 400 ans. Actuellement, cette espèce est la principale responsable des épidémies de dengue et de chikungunya dans la zone pantropicale et sa large répartition a très probablement joué un rôle important dans l’expansion récente du virus Zika. La biologie d’Ae. (Stg.) aegypti est particulièrement bien connue, ce qui n’est pas le cas de son écologie, en particulier de ses interactions avec les communautés résidentes. En adoptant une démarche pluridisciplinaire je me suis intéressé à la contribution relative des facteurs biotiques et abiotiques ainsi que de certains processus évolutifs dans la distribution de cette espèce à différentes échelles en Guyane française.Dans un premier temps j’ai participé à la révision des connaissances fondamentales sur la diversité des moustiques de Guyane. En alliant la taxonomie classique et moléculaire, cette étape a permis de découvrir plusieurs nouvelles espèces et de mettre en place des outils adaptés à la gestion de ce type de données, notamment pour une utilisation future.Dans un second temps la structuration spatio-temporelle des communautés résidentes de macro-invertébrés aquatiques a été étudiée en milieu urbain. Cela a permis de mettre en évidence l’existence d’interactions antagonistes et mutualistes avec les taxons des communautés résidentes. En particulier, le moustique autochtone Limatus durhamii Theobald 1901 semble empêcher l’établissement durable d’Ae. (Stg.) aegypti dans les milieux faiblement urbanisés via un mécanisme d’exclusion compétitive.
https://tel.archives-ouvertes.fr/tel-01405425

NNT : 2016YANE0001
tel-01405425
https://tel.archives-ouvertes.fr/tel-01405425
https://tel.archives-ouvertes.fr/tel-01405425/document
https://tel.archives-ouvertes.fr/tel-01405425/file/These_Def_Talaga.pdf

Éditeur(s) : HAL CCSD Springer Verlag (Germany)
Résumé : International audience
Today, there is increasing concern regarding the capacity ofScleractinian corals to sustain the growing number of insultsassociated with global and local changes (e.g. global warming,ocean acidification, pollution). If corals are to exist, there is anurgent need to use indicators of coral health that provide insightinto early sub lethal shifts in corals before the irreversibleeffects of exposure manifest at the population and communitylevels. This paper will provide an overview of the most relevantand appropriate indicators of coral health currently usedin traditional monitoring programs (traditional approach) orthose that could be used in a near future to improve assessmentof coral health (new and proactive approach). In addition, byusing French Polynesia coral reefs as a study case, this paperwill present how coral health was assessed in the past and howit will be in a near future.
ISSN: 0948-4280

hal-01342777
https://hal-univ-perp.archives-ouvertes.fr/hal-01342777
DOI : 10.6119/JMST-013-0813-2

Éditeur(s) : HAL CCSD
Résumé : International audience
Viral replication in the liver is generally detected by cellular endosomal Toll-like receptors (TLRs) and cytosolic helicase sensors that trigger antiviral inflammatory responses. Recent evidence suggests that surface TLR2 may also contribute to viral detection through recognition of viral coat proteins but its role in the outcome of acute viral infection remains elusive. In this study, we examined in vivo the role of TLR2 in acute infections induced by the highly hepatotrophic mouse hepatitis virus (MHV) type 3 and weakly hepatotrophic MHV-A59 serotype. To address this, C57BL/6 (wild-type; WT) and TLR2 knockout (KO) groups of mice were intraperitoneally infected with MHV3 or MHV-A59. MHV3 infection provoked a fulminant hepatitis in WT mice, characterized by early mortality and high alanine and aspartate transaminase levels, histopathological lesions and viral replication whereas infection of TLR2 KO mice was markedly less severe. MHV-A59 provoked a comparable mild and subclinical hepatitis in WT and TLR2 KO mice. MHV3-induced fulminant hepatitis in WT mice correlated with higher hepatic expression of interferon-β, interleukin-6, tumour necrosis factor-α, CXCL1, CCL2, CXCL10 and alarmin (interleukin-33) than in MHV-A59-infected WT mice and in MHV3-infected TLR2 KO mice. Intrahepatic recruited neutrophils, natural killer cells, natural killer T cells or macrophages rapidly decreased in MHV3-infected WT mice whereas they were sustained in MHV-A59-infected WT mice and MHV3-infected TLR2 KO. MHV3 in vitro infection of macrophagic cells induced rapid and higher viral replication and/or interleukin-6 induction in comparison to MHV-A59, and depended on viral activation of TLR2 and p38 mitogen-activated protein kinase. Taken together, these results support a new aggravating inflammatory role for TLR2 in MHV3-induced acute fulminant hepatitis. © 2016 John Wiley & Sons Ltd
Immunology

Droits : info:eu-repo/semantics/OpenAccess
hal-01373946
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01373946
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01373946/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01373946/file/Toll-like%20receptor%20%28tlr%29-2%20exacerbates%20murine%20acute%20viral%20hepatitis.pdf
DOI : 10.1111/imm.12627

Éditeur(s) : HAL CCSD Taylor & Francis
Résumé : International audience
Overfishing and habitat destruction due to local and global threats are undermining fisheries, biodiversity, and the long-term sustainability of tropical marine ecosystems worldwide, including in the Coral Triangle. Well-designed and effectively managed marine reserve networks can reduce local threats, and contribute to achieving multiple objectives regarding fisheries management, biodiversity conservation and adaptation to changes in climate and ocean chemistry. Previous studies provided advice regarding ecological guidelines for designing marine reserves to achieve one or two of these objectives. While there are many similarities in these guidelines, there are key differences that provide conflicting advice. Thus, there is a need to provide integrated guidelines for practitioners who wish to design marine reserves to achieve all three objectives simultaneously. Scientific advances regarding fish connectivity and recovery rates, and climate and ocean change vulnerability, also necessitate refining advice for marine reserve design. Here we review ecological considerations for marine reserve design, and provide guidelines to achieve all three objectives simultaneously regarding: habitat representation; risk spreading; protecting critical, special and unique areas; reserve size, spacing, location, and duration; protecting climate resilient areas; and minimizing and avoiding threats. In addition to applying ecological guidelines, reserves must be designed to address social and governance considerations, and be integrated within broader fisheries and coastal management regimes.
ISSN: 0892-0753

hal-01333534
https://hal-univ-perp.archives-ouvertes.fr/hal-01333534
DOI : 10.1080/08920753.2014.877763

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The replenishment and persistence of marine species is contingent on dispersing larvae locating suitable habitatand surviving to a reproductive stage. Pelagic larvae rely on environmental cues to make behavioural decisionswith chemical information being important for habitat selection at settlement. We explored the sensory worldof crustaceans and fishes focusing on the impact anthropogenic alterations (ocean acidification, red soil, pesti-cide) have on conspecific chemical signals used by larvae for habitat selection. Crustacean (Stenopus hispidus)and fish (Chromis viridis) larvae recognized their conspecifics via chemical signals under control conditions. Inthe presence of acidified water, red soil or pesticide, the ability of larvae to chemically recognize conspecificcues was altered. Our study highlights that recruitment potential on coral reefs may decrease due to anthropo-genic stressors. If so, populations of fishes and crustaceans will continue their rapid decline; larval recruitmentwill not replace and sustain the adult populations on degraded reefs
ISSN: 0025-326X

hal-01491052
https://hal-univ-perp.archives-ouvertes.fr/hal-01491052
DOI : 10.1016/j.marpolbul.2016.08.083

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Exposure to environmental polycyclic aromatic hydrocarbons (PAHs), such as benzo(a) pyrene (B(a) P), has been linked to several health-threatening risks. PAHs were also shown to hinder adrenergic receptor (ADR) responses. As we previously demonstrated that Ba) P can directly interact with the beta 2ADR, we investigated here whether B(a) P could decrease beta 2ADR responsiveness by triggering receptor desensitization phenomena. We firstly showed that exposure to B(a) P reduced beta 2ADRmediated epinephrine-induced induction of NR4A gene mRNAs and of intracellular cAMP. Analysis of beta 2ADR protein expression demonstrated that B(a) P rapidly decreased membrane expression of beta 2ADR with a subsequent degradation of receptor protein. B(a) P exposure concomitantly rapidly increased the beta 2ADR mRNA levels. The use of the beta-blockers, propranolol and ICI 118.551, demonstrated the involvement of beta 2ADR itself in this increase. However, sustained exposure to Ba) P induced a diminution of beta 2ADR mRNA steady-state as a result of the acceleration of its degradation. Together, these results show that, beside the well-known activation of the aryl hydrocarbon receptor, PAH deleterious effects may involve the dysfunction of adrenergic responses through, in part, the desensitization of beta 2ADR. This may be taken in consideration when beta 2-agonists/antagonists are administered in patients exposed to important concentrations of PAHs, e.g. in cigarette smokers.
ISSN: 2045-2322

hal-01560151
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01560151
DOI : 10.1038/s41598-017-03646-4
PUBMED : 28607424

Éditeur(s) : HAL CCSD
Résumé : International audience
Effective and sustainable prevention of work-related musculoskeletal disorders (WR-MSDs) remains a challenge for preventers and policy makers. Coordination of stakeholders involved in the prevention of WR-MSDs is a key factor that requires greater reflection on common knowledge and shared representation of workers’ activities among stakeholders. Information on workers’ strategies and operational leeway should be the core of common representations, since it places workers at the center of the “work situation system” considered by the intervention models. Participatory ergonomics permitting debates among stakeholders about workers’ activity and strategies to cope with the work constraints in practice could help them to share representations of the “work situation system” and cooperate. Sharing representation therefore represents a useful tool for prevention, and preventers should provide sufficient space and time for dialogue and discussion of workers’ activities among stakeholders during the conception, implementation and management of integrated prevention programs
Safety and Health at Work

hal-01279095
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01279095
DOI : 10.1016/j.shaw.2016.02.001
PUBMED : 27340607

Éditeur(s) : HAL CCSD
Résumé : International audience
Until the end of the 20th century, heritage was mainly defined in the Caribbean, as in the entire world, by an european conception (linked with the formation of national identities), founded on the value of tangible heritage (rare, ancient objects, monuments and materials) as an historic proof of the value of cultures and peoples. Poets in the Caribbean hardly criticize this evidence that contributed to inferiorized people. Memory and imagination played a central role in the building of a Caribbean cultural identity. Poets tried to show how the common could rise from different patterns, diversity instead of unity, creation instead of fixity. Nevertheless, In the 21st century, frameworks are not available to deal with Caribbean heritage in its diversity (monuments, material, natural and intangible...) and complexity whereas it constitute a challenge for a sustainable society and can play a fundamental role in education as in tourism.
Jusqu'à la fin du XXe siècle, le patrimoine dans la Caraïbe comme ailleurs dans le monde, répondait principalement à une conception européenne (liée à la formation des identités nationales) fondée sur la valeur positive du patrimoine matériel comme preuve historique de la valeur des cultures et des peuples. Les poètes caribéens ont déconstruit ce cadre, instrument de l'infériorisation des individus. La mémoire et l'imagination ont joué un rôle central dans la construction d'une identité culturelle caribéenne. Ils ont tenté de montrer que le commun pouvait émerger de modèles différents, opposant à l'unique, le divers et à la fixité, la création. Cependant, au XXIe siècle, la Caraïbe ne dispose pas d'un cadre pour traiter son patrimoine dans sa diversité (patrimoine matériel, immatériel, naturel) et sa complexité alors que le patrimoine constitue un défi pour le développement durable des sociétés et peut jouer un rôle fondamental dans l'éducation et le tourisme.
Caribbean Studies Association annual conference
Port-au-Prince, Haiti

hal-01612909
https://hal.univ-antilles.fr/hal-01612909

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Carbonation of peridotite is a widespread process in nature, with emerging societal and environmental implications through geological storage of CO2. We studied the micro- and nano-scale structures associated with the carbonation of peridotite pervaded by a CO2-rich water and the induced changes of its hydrodynamic properties. Focused ion beam (FIB) nanotomography was coupled with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. An experimental sample of dunite core percolated by a CO2-rich fluid (pCO2 = 11 MPa) at 160 °C was compared with a naturally carbonated sample from the Atlantic Ridge (Exp. IODP 304). Results of the 8-days percolation experiment show continuous alteration of olivine into magnesite locally associated with a poorly crystalline serpentine-type mineral referred to as proto-serpentine. The experiment is also characterized by an overall decrease in rock porosity (from 7.7 to 6.4%) and permeability (from 8.5 × 10− 16 to 1.7 × 10− 16 m2). The primary inter-granular porosity (1 to 10 μm) is progressively filled with magnesite, leading to the overall decrease of permeability. At the same time, a secondary small-scale porosity (10 nm to 1 μm) is created at the tip of the dissolution features along the (010) cleavage planes of olivine grains. Carbonate crystals grow within these etch-pit structures behind the dissolution front. Dissolution and precipitation occur at a relative rate that maintains the secondary porosity over the timescale of the experiment (i.e. carbonate growth has to be the slowest one). This process is interpreted as an interface coupled dissolution-precipitation mechanism of olivine carbonation. Proto-serpentine is only formed in highly reduced flow areas, such as small olivine etch-pits (10 to 500 nm wide), which are more isolated from CO2 input. SEM-FIB analyses show the 3D preferential orientation of the dissolution-precipitation planes within a given olivine grain. It suggests the formation of lateral connections between the etch-pits (infra-micrometric “channels”) providing access to reactants and removing reaction products at the reaction sites. The experimental results show that olivine dissolution and magnesite precipitation converge to a quasi-steady state resulting in a constant carbonation rate controlled by reaction kinetics and not by mass transfer for this flow regime. The system self-regulates, independently of the porosity change at least during this incipient stage of olivine carbonation. Similar textures are observed in natural samples collected at 170 m-depth in the vicinity of veinlets driving late fluids down into the cooling oceanic lithosphere. This suggests that similar mechanisms are active in nature and can play an important role in the late, low temperature alteration stages of fractured peridotite. These results also highlight the critical role of nm-scale spatial arrangement of dissolution and precipitation features on mass transfers and on the sustainability of olivine carbonation through coupled dissolution-precipitation processes.
ISSN: 0009-2541

hal-01684733
https://hal.archives-ouvertes.fr/hal-01684733
DOI : 10.1016/j.chemgeo.2017.11.013

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Ecological signs of Earth's biosphere forewarn an alarming trajectory towards a global mass-extinction. Assessing species performance and susceptibilities to decline is essential to comprehend and reverse this trend. Yet it is challenging, given difficulties associated with quantifying individual and population processes that are variable across time, space, and life-stages. We describe a new approach to estimating and comparing species performances that combines empirical data, a novel theoretical consideration of population dynamics, and modern statistics. Our approach allows for a more realistic continuous representation of individual performances along development stages while taking into account non-linearity, and natural variability as captured by spatio-temporally replicated observations. We illustrate its application in a coral meta-assemblage composed of populations of the three major reef-building taxa Acropora, Pocillopora, Porites. Using a unique set of highly replicated observations of individual coral dynamics under various environmental conditions, we show how taxa differ in their investment in recruitment and size-specific aptitude for growth and survival, notably through different use of clonal shrinkage, fragmentation, fission, and fusion processes. Our results reveal contrasting life-history trade-offs among taxa which, along with differing patterns of density-dependent recruitment, modulate species responses to decline. These differences in coral life history traits reflect opposing life-strategies, imply regulation at differing life-stages, and explain divergence in species trajectories. Our findings indicate a high potential for resilience in Pocillopora and Porites populations, thanks respectively to a sustained recruitment that promotes demographic elasticity through replacement of individuals, and a steady resistance to mortality which confers persistence through lingering of individuals. Resilience in Acropora appears more arbitrary, given high susceptibility to perturbations and dependency of recruitment on presence of established local populations. We identify management actions that can complement Acropora's life history and benefit recovery of its populations following mortality events. Our regression-modelling approach to quantifying and comparing species performances in different population processes is applicable to all taxa, as illustrated even those with complex clonal life histories, and can be implemented at wide spatio-temporal and taxonomic coverage. It can promote more accurate representation of species dynamics in both descriptive and predictive modelling approaches. The semi-parametric contrast curve method we develop facilitates comparing response variables along continuous explicative metrics while accounting for multiple sources of complexity in empirical data. It should widely benefit investigations in ecology and quantitative science.
ISSN: 1476-945X

hal-01212337
https://hal-univ-perp.archives-ouvertes.fr/hal-01212337
DOI : 10.1016/j.ecocom.2015.07.003