HAL - La Rochelle Université, Archives Ouvertes
Not a member yet
19516 research outputs found
Sort by
Risk-taking behavior related to mercury contamination in a high Arctic seabird
No full textInternational audienc
Exposure to a mixture of organic pollutants in a threatened freshwater turtle Emys orbicularis: effects of age, sex, and temporal variation
No full textInternational audienceFreshwater ecosystems constitute major sinks for organic contaminants, increasing anthropogenic pressures and threatening the unique biodiversity they harbour. In addition to persistent legacy compounds, such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), various pollutants are less persistent but are chronically released, including polycyclic aromatic hydrocarbons (PAHs), phthalate diesters (PAEs), pyrethroid pesticides, and insect repellent. Heretofore, these pollutants have received insufficient attention in freshwater reptiles, considering their potential to trigger detrimental effects on organisms. During two years (2019 and 2020), we quantified plasma levels of 46 compounds from 7 chemical families in two monitored populations of the protected European pond turtle (Emys orbicularis) in the Camargue wetland, France. PAHs and PAEs were found predominantly and concomitantly, with similar occurrences and levels in the two populations. We observed similar inter-annual variations in PAHs and PAEs with differences between males and females, highlighting the need for a better assessment of the role of sex in the exposure pathway and the toxicokinetics of contaminants, especially in turtles. The negative relationship between PAH levels and age, as well as the high intra-individual variation in levels of both contaminant families, provides further evidence of limited bioaccumulation of these pollutants in the blood of E. orbicularis. This could be explained by the metabolic biotransformation of parent compounds, highlighting the need to quantify the levels of PAH metabolites and phthalate monoesters. Finally, our work underscores the importance of long-term monitoring to better determine the vulnerability of turtle populations already exposed to a wide range of contaminants.</div
2. Mise en images : L’iconographie de la révolution aux États-Unis depuis le XVIIIe siècle
No full textInternational audienc
Publicité télévisée des enseignes de distribution : « le loup plaidant contre le renard »
No full textInternational audienc
Effect of recycled waste cardboard chips on the physico-thermal-hygric properties of hemp-lime biocomposites
No full textInternational audienceBuildings are major contributors to global energy consumption and environmental impacts, highlighting the critical need for sustainable and energy-efficient insulation materials. Biocomposites incorporating recycled cardboard have emerged as promising solutions for such applications; however, their production methods are often labor-intensive, energy-demanding, and time-consuming. To address these limitations, the present study explores the feasibility of using recycled waste cardboard chips (RWCC) as a partial or complete replacement for conventional hemp shives in hemp-lime biocomposites. A simplified, low-energy, and rapid processing methodology was developed in which untreated RWCC, cut directly from post-consumer cardboard, were incorporated into hemp-lime matrices without any pre-treatment. The RWCC were mixed using a rapid blending procedure and lightly compacted, thereby eliminating the need for grinding, crushing, soaking, defibrating, extended compaction, or thermal curing. Substitution ratios ranging from 0 to 100 wt% were investigated to assess physical, thermal, and hygric properties. The resulting biocomposites exhibited low densities (514-682 kg/m 3 ) and high porosities (68.7-75.5%), leading to low thermal conductivity (0.0775-0.0919 W/(m⋅K)), high heat capacity (972-1036 J/(kg⋅K)), low thermal diffusivity (1.25-1.51 × 10 -7 m 2 /s), and low thermal effusivity (200-248 J/(m 2 ⋅K⋅s 1/2 )), thereby enhancing both insulation performance and thermal inertia. Adequate vapor permeability (1.24-2.12 × 10 -11 kg/(m⋅s⋅Pa)) and moisture buffer capacity (0.66-1.59 g/(m 2 ⋅%RH)) were also observed, supporting healthy indoor environments. Overall, the results demonstrate the feasibility of valorizing untreated RWCC in hemp-lime matrices, achieving properties comparable to those of established bio-based insulation materials while significantly reducing processing intensity
Innovation low-cost et open source : l’exemple d’un nouvel outil de monitoring de la ressource en eau dans les marais littoraux
No full textInternational audiencePrecise monitoring of water levels in marshland wetlands is crucial for reconciling agropastoral activities with biodiversity and developing hydraulic management strategies. Innovations using low-cost technologies hold promise for equipping these territories, which require a dense network of measurement points. A tool, developed at experimental sites along the Atlantic coast, uses simple materials and a geolocated, opensource data acquisition technology, providing real-time monitoring that is easily deployable, robust, and reproducible. It is at the heart of developing a management plan involving a representative collective from the various marshland users. It represents a major opportunity for large-scale instrumentation to better understand the hydrological regimes underlying the functions provided by marshland wetlands. The analysis of this low-cost and open-source innovation raises broader questions about innovation in the management of a common good such as water.Le suivi précis des niveaux dans les zones humides de marais est crucial pour concilier les activités agropastorales et la biodiversité et construire des stratégies de gestion hydraulique. Les innovations mobilisant des technologies à bas coût sont prometteuses pour équiper ces territoires qui nécessitent un réseau dense de points de mesure. L’article étudie un outil expérimenté sur deux marais du littoral atlantique. Utilisant des matériaux simples et une technologie d’acquisition de données géolocalisées, libre et ouverte, il offre un suivi en temps réel, facilement déployable, robuste et reproductible. Il est au cœur de la construction d’un plan de gestion embarquant un collectif représentatif des différents usages du marais et il constitue une opportunité d’instrumentation massive pour mieux comprendre les régimes hydriques sous-jacents aux fonctions des marais. L’analyse de cette innovation low cost et open source questionne plus largement les travaux sur l’innovation dans la gestion d’un bien commun comme l’eau. Codes JEL : Q550, Q570, Q250, Q28
Telomere length decreases with age and reflects early-life environment but not adult condition in a long-lived migratory bird
No full textInternational audienc
Physiological and behavioural responses of wandering albatross chicks (Diomedea exulans) to novel and non-novel predators
No full textInternational audienceIn long-standing predator-prey systems, prey typically evolve costly responses to predation risk. How prey respond to novel predators is less investigated. We explored physiological (corticosterone, triglyceride), morphological (body condition) and behavioural (defensive posture) responses of wandering albatross (Diomedea exulans) chicks to a novel predator, the feral cat (Felis catus) in Kerguelen archipelago. We implemented a semi-experimental design to increase the variance in cat abundance by regulating cat populations in certain zones of the study colony. The aforementioned chick traits were then monitored and analysed at the zone scale, by comparing nests located within regulated and non-regulated zones, and at the nest scale, by recording cat abundance through intensive camera traps monitoring. This fine-scale approach further enabled us to investigate how chicks responded to southern giant petrels (Macronectes giganteus), an opportunistic predator-scavenger that has co-evolved with albatrosses. Cat abundances had no effect on chick traits. In contrast, higher abundances of giant petrel were associated with an elevated rate of corticosterone increase and lower triglyceride levels. In accordance with these results suggesting a more accurate perception of predation risk mediated by giant petrels than by cats, chicks were more prone to display a defensive posture when facing a giant petrel than a cat. We discuss these results in the light of contrasting evolutionary histories and predation patterns between albatrosses and their predators, and we emphasise that studies of predator impacts on prey populations must consider both the direct and indirect effects of all predators, as well as their interactions
Effects of lateral hydrological connectivity on the taxonomic and functional structure of fish communities in Saône river floodplains (France): implications for non‐native species distribution.
No full textInternational audienceLarge alluvial plain rivers provide a complex mosaic of freshwater habitats characterised by a lateral hydrological connectivity (LHC) gradient between the main channel and floodplains. This connectivity plays a key role in structuring aquatic communities, influencing species distribution, diversity, and ecosystem processes. The aims of our study were to assess the effects of the LHC gradient on both fish taxonomic and functional diversity, and to characterise the effects of this connectivity on the distribution of non‐native species. Community data were gathered through electrofishing at five sites in the main channel of the Saône River (France), and in four permanently (parapotamic) and four occasionally (plesiopotamic) connected oxbows. Functional diversity was investigated using a trait‐based approach as surrogates of ecosystem processes. A total of 28 fish species were identified, including 14 non‐native species. Our results show that main channel and plesiopotamic oxbows exhibited distinct compositional and structural patterns of fish communities, while parapotamic oxbows displayed an intermediate composition and community structure. Taxonomic and functional diversity decreased along the lateral continuum from the main channel to plesiopotamic waterbodies. In contrast, while non‐native species richness was similar between the main channel and floodplains, their densities were higher in floodplain oxbows. These findings highlight the prominent role of hydrological connectivity in sustaining both taxonomic and functional diversity in riverine ecosystems. Fish community variations between habitats may be explained by physical changes resulting from reduced connectivity, primarily characterised by a loss of depth and surface area, which in turn affect a broad spectrum of abiotic and biotic factors. High densities of non‐native species in lentic environments like oxbows can be attributed to specific abiotic conditions (e.g., hypoxia, rapid temperature fluctuations and eutrophication) and the greater tolerance and plasticity of non‐native species compared to native species. Additionally, the absence of predators reduces top‐down control and intensifies competition with native species for resources. Conservation and management strategies should prioritise preserving and restoring connectivity to support native fish communities, limit the dominance of non‐native species, and maintain the ecological integrity of freshwater ecosystems
Villes d'Asie : entre imaginaire et réalité
No full textVues d’Europe, les villes d’Asie semblent à l’écart du monde, repoussées à sa périphérie, parfois réduites à de simples objets de curiosité. Cependant, certaines d’entre elles s’enorgueillissent d’un passé prestigieux. Centres cosmopolites avant l’ère de la mondialisation ou encore hauts lieux culturels, d’aucunes continuent même de bénéficier de ce statut. Les villes d’Asie ont également été lieux de passage ou d’immigration ; diverses populations et voyageurs du monde entier s’y sont toujours déplacés pour d’innombrables raisons. Le brassage des populations et les échanges commerciaux et culturels n’ont toutefois pas toujours été idylliques. Celles-ci ont également fait l’objet de convoitises, d’invasions, de guerres et de colonisation. Échanges et métissages se sont également conjugués avec des expériences douloureuses et déchirantes. Sources de fascination ou de détestation, ces villes asiatiques ont longtemps attiré le regard d’auteurs et d’artistes du monde entier. Ces derniers les ont étudiées sur les plans historique, géographique, sociologique, anthropologique, mais aussi sur le plan de l’expression littéraire et artistique à travers les romans, la poésie, le cinéma, la photographie, l’architecture, etc. Ainsi, loin d’être fermées et excentrées, les villes asiatiques ont souvent été des espaces cosmopolites et ouvertes au monde. L’objectif de cet ouvrage est de prolonger cette idée d’ouverture sur le monde et d’offrir à tout un chacun l’occasion de découvrir des aspects méconnus de ces villes asiatiques, à encourager la démarche qui consiste à confronter l’imaginaire et la réalité des mondes passés et contemporains tout en adoptant un point de vue géocritique