HAL - La Rochelle Université, Archives Ouvertes
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De la connexion terre-mer à la connexion air-mer. Le rêve d’une intermodalité intégrale du transport de voyageurs dans les ports français de l’entre-deux-guerres
No full textInternational audienc
Seasonal and inter-annual dynamics in the energy seascapes of a marine top predator
No full textInternational audienceEcosystems are undergoing global changes that disrupt energy transfer across trophic levels, reducing energy availability and destabilizing predator–prey interactions. In marine systems, small pelagic fish (SPF) are key energy vectors to higher trophic levels. In the Bay of Biscay, common dolphins rely heavily on SPF, which have declined in size and condition in recent decades, while dolphin by-catch has increased. To explore whether prey field changes could explain shifts in dolphin distribution, we mapped prey energy by integrating biomass, size and energy content for four SPF species (sardine, anchovy, sprat and small horse mackerel), representing 80% of the dolphin diet. We analysed acoustic survey data from PELGAS (2000–2023) and JUVENA (2009–2023) to assess temporal and spatial changes in prey energy. Energy per prey has declined, mainly due to decreasing fish length and energy density. Total energy available for common dolphin remained stable, through increase of lower-energy anchovies and decrease of larger, higher-energy sardines. Spatial redistributions were also evident, with sardine energy becoming more coastal and anchovy energy expanding northward. These energy seascapes dynamics, probably climate-driven, may have led dolphins to forage closer to shore, in areas of higher fishing pressure, thereby contributing to the recent rise in by-catch
Phenological plasticity and its temperature‐related drivers in common songbirds across Europe
No full textInternational audiencePhenological plasticity—the ability of organisms to adjust the timing of life-history events in response to environmental variability—is the primary adaptive mechanism for many organisms to changing seasonality (e.g., earlier spring). By enabling alignment between life-history events and resource availability, it helps to maintain fitness despite changing environmental conditions. Theory predicts that phenological plasticity should vary among populations because of heterogeneity in environmental variability, and among species because of differences in life-history (e.g., migration distance) and phylogenetic constraints. However, comprehensive, multi-species, and cross-population analyses of phenological plasticity remain scarce. Here, we address this gap by using a unique, four-decade dataset from Europe-wide monitoring of common songbirds. Our approach reveals how variation in phenological plasticity is structured according to site temperature properties, both within and across species. We found that long-distance migrants generally exhibit lower plasticity than residents or short-distance migrants, highlighting a fundamental constraint tied to migration strategy. Within species, populations inhabiting sites with predictable temperature profiles showed slightly stronger plastic responses, particularly among single-brooded species and those adapted to warmer breeding conditions. Notably, populations from the fastest-warming regions demonstrated marginally greater plasticity, regardless of other ecological traits, suggesting a global tendency for increased responsiveness in rapidly changing climates. These findings confirm and extend patterns previously observed at smaller scales, offering a more nuanced understanding of how local temperature conditions drive phenological plasticity. By demonstrating that the interplay between local environmental conditions and life-history traits underpins variation in breeding phenological responses, our study refines the current framework for predicting adaptive potential across populations and species under climate change
Measuring the sensitivity of Density Surface Models to partially biased or unknown Effective Strip Widths
No full text2025-02-05 1 Introduction 2 Set up the data 2.1 Initialise the environment 2.2 Initialise the species 2.3 Initialise and run the survey 2.4 Format the data for modelling 3 Build the species distribution model 4 Answering our study question: how sensitive is the model to dummy ESWs? 4.1 Homogeneously-altered ESW 4.2 Randomly-altered ESW 4.3 Spatially-localised dummy ESW 5 Conclusion References</div
The Pathophysiological Functions of Heparanases: From Evolution, Structural and Tissue‐Specific Perspectives
No full textInternational audienceHeparanase 1 (HPSE1) is a unique endoglycosidase responsible for the enzymatic cleavage of heparan sulfate, thereby playing important functions in cancer processes. In contrast, the structurally related Heparanase 2 (HPSE2) lacks catalytic activity and appears to counteract HPSE1 activities. However, contradictory observations in various pathologies highlight the need for a better understanding of the respective contributions of both heparanases. In this review, we provide a comprehensive resource about the biology of HPSE1 and HPSE2 based on findings from different mouse models, with an emphasis on immune cells and their involvement in skin pathophysiology. In addition, we explore the evolutionary relationships between the two heparanases and describe the structure–function of HPSE2 using the advanced protein‐prediction tool AlphaFold 3 (AF3). These approaches unveil new insights for deciphering the functional molecular determinants that distinguish HPSE1 from HPSE2
Progressive lifespan modifications in the corpus callosum following a single concussion in juvenile male mice monitored by diffusion MRI
No full textInternational audienceIntroduction: The vulnerability of white matter (WM) in acute and chronic moderate-severe traumatic brain injury (TBI) has been established. In concussion syndromes, including preclinical rodent models, lacking are comprehensive longitudinal studies spanning the mouse lifespan. We previously reported early WM modifications using clinically relevant neuroimaging and histological measures in a model of juvenile concussion at one month post injury (mpi) who then exhibited cognitive deficits at 12mpi. For the first time, we assess corpus callosum (CC) integrity across the lifespan after a single juvenile concussion utilizing diffusion MRI (dMRI).Methods: C57Bl/6 mice were exposed to sham or two severities of closed-head concussion (Grade 1, G1, speed 2 m/s, depth 1 mm; Grade 2, G2, 3 m/s, 3 mm) using an electromagnetic impactor at postnatal day 17. In vivo diffusion tensor imaging was conducted at 1, 3, 6, 12 and 18mpi and processed for dMRI parametric maps: fractional anisotropy (FA), axial (AxD), radial (RD) and mean diffusivity (MD). Hemispheric CC and regional CC data were extracted. To identify the biological basis of altered dMRI metrics, astrocyte and microglia in the CC were characterized at 1, 12 and 18 mpi by immunohistochemistry. Results: Hemispheric CC analysis revealed altered FA and RD trajectories following juvenile concussion. Shams exhibited a temporally linear increase in FA with age while G1/G2 mice had plateaued FA values. G2 concussed mice exhibited high variance of dMRI metrics at 18mpi, which was attributed to the heterogeneity of TBI on the anterior CC. Regional analysis of dMRI metrics at the impact site unveiled significant differences between G2 and sham mice. The dMRI findings appear to be driven, in part, by loss of astrocyte morphology. Conclusion: For the first time, we demonstrate progressive perturbations to WM of male mice after a single juvenile concussion across their lifespan. The CC alterations were dependent on concussion severity with elevated sensitivity in the anterior CC that was related to astrocyte and microglial morphology changes. Our findings suggest that long-term monitoring of children with juvenile concussive episodes using dMRI is warranted, focusing on vulnerable WM tracts
L’ostréiculture et les questions environnementales : utilisation d’un corpus d’images en sociologie des groupes professionnels
No full textInternational audienceColourful plastic on a beach, tractors on the foreshore, sheds in the salt marshes… The stage is set to describe the use of photography in research on the occupational group of oyster farmers. This article explores the methodological process of a pioneering sociology that uses images in a study, exploring the status of these images. Three corpuses of photographs were used to further our understanding of this profession, which has seen the upward trajectories of both individuals and collectives hampered by the environmental crisis. The social identity of these oyster farmers vacillates between tradition and the search for a certain image of modernity, which tends to appear as a recurrent rejection of disorder. Their historical culture of working with hazards, including, to a certain degree, climate change, encourages them to engage in new adaptation strategies.Plásticos de colores en la playa, tractores en la zona intermareal, la marisma y sus cabañas. La escenografía es ideal para evocar el uso de la fotografía en una investigación que trata sobre la comunidad de personas ostricultoras profesionales. El presente artículo explora el recorrido metodológico de un sociólogo que por primera vez emplea imágenes para realizar una encuesta y reflexiona sobre la función de estas. Se han utilizado tres corpus de fotografías para comprender mejor esta profesión, cuya trayectoria ascendente tanto para los individuos como para el colectivo ha perdido intensidad como consecuencia de la crisis ambiental. La identidad social de estas personas ostricultoras oscila entre la tradición y la búsqueda de una cierta imagen de modernidad, representada particularmente por una aversión recurrente al desorden. Una cultura histórica de lo imponderable, con distintos niveles de integración de la problemática del cambio climático, los incita a adoptar nuevas estrategias de adaptación.Des plastiques colorés sur une plage, des tracteurs sur l’estran 18 , le marais et ses cabanes. Le décor est posé pour évoquer l’usage de la photographie dans une recherche portant sur le groupe professionnel des ostréiculteurs. L’article explore le cheminement méthodologique d’une sociologue mobilisant pour la première fois les images dans une enquête, s’interrogeant sur le statut de celles-ci. Trois corpus de photographies sont venus nourrir la compréhension de cette profession dont la trajectoire ascendante à l’échelle des individus comme du collectif est ralentie par la crise environnementale. L’identité sociale de ces ostréiculteurs oscille entre tradition et quête d’une certaine image de modernité, s’incarnant notamment dans un rejet récurrent du désordre. Une culture historique de l’aléa, intégrant plus ou moins la question du changement climatique, les incite à engager de nouvelles stratégies d’adaptation
Assessment of spatial distribution of organic contaminants and metallic compounds on a tropical island’ coral reef fish communities
No full textInternational audienceThe New Caledonian archipelago is an important hotspot of marine biodiversity. Due to mining activities, urbanization, and industrialization, significant amounts of contaminants are discharged into the lagoon. This study analysed the concentrations, spatial distribution, and potential drivers of 14 metallic compounds and trace elements (MTEs) and 22 persistent organic pollutants (POPs) in ~400 coral reef fish sampled from various sites around New Caledonia, across a gradient from mining centers to remote, uninhabited locations. Boosted regression trees modelling explained between 61 and 86 % of the global variation in MTEs and POPs concentration. Fish body size emerged as the most important correlate of MTEs and POPs concentrations in coral reef fish. Monthly rainfalls were the second most important variable for POPs, whereas the reef area was the second variable explaining MTE concentrations. Our modelling approach allowed us to predict and map the distribution of concentrations at the fish community level for 17 contaminants (9 MTEs and 8 POPs). Predicted concentrations ranged from ~1.5 ng.g -1 (β-endosulfan) to ~11.5 μg.g -1 (Ni), and revealed a widespread contamination throughout the lagoon, from the coast to the barrier reef. Contamination by mining-related elements (Ni, Cr…) were clearly influenced by the surface area of mining registry and to lithology to a lesser extent, whereas Hg contamination strongly depended on biological variables. Our study is the largest of its kind at the archipelago scale, combining data on 36 contaminants in ~400 fish samples with a modelling framework offering insights into underlying processes and spatial data for policy use
Exposure to pesticides is correlated with gut microbiota alterations in a farmland raptor
No full textInternational audienceThe gut microbiota is crucial for host health and can be impacted by various environmental disruptions, yet the effects of multiple pesticide exposures on farmland organisms' microbiomes remain largely unexplored. We assessed microbiota changes in a wild apex predator exposed to multiple pesticides in agricultural landscapes. Pesticides, including acetochlor and quinoxyfen, which are supposed to be banned, were significantly positively correlated with certain key bacteria from Actinobacteria, Alphaproteobacteria and Gammaproteobacteria classes. Our results light up the potential collateral effect of pesticides on gut bacterial assemblages through unknown mechanisms. These effects could result in dysbiosis and the promotion of potential pathogens and/or the selection of bacteria that might allow the organism to detoxify the organism. Although formal metagenomic analyses would be required soon, these microbial shifts underline the broader ecological consequences of pesticide exposure, emphasising the need for integrated biodiversity conservation and ecosystem management to protect environmental and public health