HAL Université des Antilles
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Flood Frequency Analysis in West Africa
No full textInternational audienceABSTRACT Devastating flood events are recurrently impacting West Africa. To mitigate flood impacts and reduce the vulnerability of populations, a better knowledge on the frequency of these events is crucial. The lack of reliable hydrometric datasets has hitherto been a major limitation in flood frequency analysis at the scale of West Africa. Utilising a recently developed African database, we perform a flood frequency analysis on the annual maximum flow (AMF) time series, covering 246 river basins in West Africa, between 1975 and 2018. Generalized extreme value (GEV) and Gumbel probability distributions were compared to fit AMF time series with the L‐moments, Maximum Likelihood (MLE) and Generalized Maximum Likelihood (GMLE) methods. Results indicated that the GEV distribution with the GMLE method provided the best results. Regional envelope curves covering the entire West African region with unprecedented data coverage have been generated for the first‐time providing insights for the estimation in flood quantiles for ungauged basins. The correlation between flood quantiles and watershed properties shows significant correlations with catchment area, groundwater storage, altitude and topographic wetness index. The findings from this study are useful for a better flood risk assessment and the design of hydraulic infrastructures in this region, and are a first step prior to the development of regional approaches to transfer the information from gauged sites to ungauged catchments
Multidecadal changes in hydrological droughts across Sub-Saharan Africa
No full textInternational audienc
Deep divergence time within the Mediterranean narrow endemic plant Arenaria provincialis (Caryophyllaceae)
No full textData used in this study were produced by the Molecular and Cell Biology facility (IMBE, Aix Marseille University) and by the Plateform GeT‐PlaGe ‐ Genotoul facilty (Toulouse University). All bioinformatics were done on the High-Performance Computing Cluster from the Pytheas IT facility (OSU Institut Pytheas Aix Marseille Univ). The PNCal delivered the authorization to collect plant material.International audienceThe origin of narrow endemic plants is a long-standing issue in Mediterranean biogeography. Estimates of divergence time may provide new insights into the likely pivotal periods in the evolutionary history of narrow endemics. Here, based on transcriptomic data and benefiting from the phylogenomic data provided by the Plant and Fungal Trees of Life Project (PAFTOL), we examined the origin of the narrow endemic plant Arenaria provincialis. We used several nuclear and plastid loci to conduct divergence time analyses embracing uncertainty of node age calibrations, allowing us to provide a new time tree for the plastid lineages of this species. The results clearly support a deep divergence time within A. provincialis that likely occurred during the Pliocene. This timeline shows that the evolutionary history of A. provincialis is closely linked to the geological and climatic changes that shaped the massifs of Provence (southeast France) before the Pleistocene. Our study also illustrates the contribution of the open and comprehensive PAFTOL project to divergence time analyse
On the Variation of Structural Divergence Among Residues in Enzyme Evolution
No full textInternational audienceABSTRACT Structural divergence varies among protein residues, yet this variation has been largely overlooked compared with the well‐studied case of sequence rate variation. Here we show that, in families of functionally conserved homologous enzymes, structural divergence increases with both residue flexibility and distance from the active site. Although these properties are correlated, modeling reveals that the pattern arises from two independent types of evolutionary constraints: non‐functional and functional. The balance between these constraints varies widely across enzyme families, from non‐functional to functional dominance. As functional constraints strengthen, structural divergence patterns are reshaped, becoming increasingly distinct from flexibility patterns and breaking the commonly assumed correspondence between evolutionary and dynamical structural ensembles. Active sites are more structurally conserved than average, but this conservation stems not only from functional constraints. Because active sites typically lie in rigid regions where non‐functional constraints are high, both constraint types contribute comparably on average, with dominance shifting from one to the other depending on active‐site rigidity. Together, these findings revise two long‐standing assumptions: that evolutionary structural variation universally mirrors protein dynamics and that active‐site conservation reflects functional requirements alone. Both depend on the balance between non‐functional and functional constraints that shape enzyme structural evolution
Shear zone memory revealed by in-situ Rb-Sr and Ar/Ar dating of Pyrenean and Alpine tectonic phases in the external Alps
No full textInternational audienceThe combination of Rb-Sr and Ar/Ar dating methods with high-resolution mineralogical investigation allows deciphering the multiphase history of shear zones and serves as a tool for tectonic reconstructions. However, the interpretation of dates obtained by these two methods in relation to cooling, fluid circulation or to deformationinduced (re)crystallization remains controversial. Here, we apply the in situ 87 Rb/ 87 Sr and Ar/Ar dating methods to shear zone minerals used together with step heating Ar/Ar dating in several case studies with contrasting structural and metamorphic histories along the External Crystalline Massifs (ECMs) of the SW Alps. Our results emphasize polyphase deformation and highlight a variable behaviour of Rb-Sr and K-Ar systems in shear zones. This study provides new constraints about the timing, conditions and mechanisms of deformation in the southern ECMs of the Western Alps. The inherited crustal-scale Variscan shear zones have been reactivated several times in a thick-skin mode since the Late Cretaceous. An early N-S compressional phase impacted the SW Alps mainly at around ~80-70 and ~40 Ma in the Argentera and Pelvoux shear zones, but this signal is not documented further north. This signal is better preserved in the southern Pelvoux massif, with a Rb-Sr age of 79.7 ± 3.7 Ma. There is also a significant compressional deformation on the W-Alpine scale at 34-32 Ma, associated with underthrusting beneath the Penninic Frontal Thrust (PFT). Two compressional deformation pulses occur at 26 and 22-20 Ma in the southern Argentera Massif, corresponding to the onset of transpressive deformation induced by the anti-clockwise rotation of the Adriatic Plate. Finally, the last phase of deformation around 18-15 Ma concerns only the NW Alps, in the Beaufortain massif, which was buried under the Mont-Blanc massif, during the propagation of deformation leading to the development of the frontal fold and thrust belt of the SW Alps. Our results also show that the southern Pelvoux massif already reached a temperature around 300°C at a depth of 10-15 km depth during the Late Cretaceous. This range of temperature and pressure conditions is broadly similar to that reached in the ECMs during the Cenozoic deformation stages
GENDER AND FISHERIES : THE REPUBLIC OF HAITI
No full textFisheries in Haiti are relatively underdeveloped, with women making critical yet often underappreciated contributions, predominantly as fish processors and traders (‘machanns’ and ‘madan saras’). Beyond these roles, women invest in fishing activities, assist with fishing trip preparations, build and maintain fishing equipment, innovate in food processing and storage, engage in shore-based harvesting, generate alternative income streams and increasingly contribute to fishers’ associations. Haiti is unique among Caribbean nations for having ministerial level government structures tasked with improving the status and rights of women, combined with a constitutional requirement that 30% of elected and appointed national positions be held by women. Grassroots organizations and women's rights activists have made substantial progress in advocating for gender equality. Nevertheless, female political participation remains limited and gender-based violence is a serious and persistent concern. Ongoing socio-political instability and Haiti’s high vulnerability to natural disasters has further hindered progress. It is important to note that the deteriorating security situation manifests differently in urban and rural areas, with most challenges concentrated around urban centres and fishing communities located in mostly rural settings. This fact sheet provides an overview of the role of seafood production in Haiti, with a focus on gender dimensions, highlighting opportunities to strengthen gender equity and women’s empowerment in the sector and beyond. It is part of a series meant to offer development agency employees, government agencies, NGOs, funders, and researchers, with a snapshot of gender and fisheries to inform the planning and delivery of relevant activities these actors might be involved in or are in the process of developing
Illégalité de la circulaire relative à la localisation du centre des intérêts matériels et moraux
No full textInternational audienceNote sous TA Toulouse, 19 mars 2025, no 220525
Role of science and scientists in public environmental policy debates: The case of EU agrochemical and Nature Restoration Regulations
No full textInternational audienceZusammenfassung Um den Verlust der Biodiversität aufzuhalten, den Klimawandel zu bremsen und die langfristige Nachhaltigkeit von ländlichen und städtischen Gebieten zu erhalten, sind dringend politische Maßnahmen erforderlich. Umweltpolitische Maßnahmen lösen jedoch häufig Widerstand und stark polarisierte öffentliche Debatten aus, wobei einige Akteure pseudowissenschaftliche Behauptungen aufstellen. Dies gibt Anlass zur Besorgnis über den zunehmenden Einfluss von Fehlinformationen auf die Politikgestaltung. Hier analysieren wir die Rolle von Wissenschaft und Forschenden in der öffentlichen Debatte über zwei Rechtsvorschriften, die 2022 von der Europäischen Kommission als Teil des Green Deal vorgeschlagen wurden, nämlich die Verordnung zur Wiederherstellung der Natur (NRR) und die Verordnung zur nachhaltigen Verwendung von Pflanzenschutzmitteln (SUR). Zunächst untersuchen wir die wichtigsten Behauptungen gegen diese beiden vorgeschlagenen Politikinstrumente und stellen sie wissenschaftlichen Erkenntnissen gegenüber. Wir zeigen, dass diese Behauptungen die umfangreiche wissenschaftliche Evidenz außer Acht lassen, dass die Wiederherstellung der Natur und die Verringerung des Einsatzes von Agrochemikalien für die Aufrechterhaltung einer langfristigen landwirtschaftlichen Produktion und für die Verbesserung der Ernährungssicherheit unerlässlich sind. Die Kritiker verkennen auch, dass die NRR und der SUR neue Beschäftigungsmöglichkeiten schaffen und Innovationen anregen können, mit hohen Renditen und zahlreichen Nutznießenden in der Gesellschaft, die den Übergang zu nachhaltigen Produktions‐ und Konsummodellen fördern können. Zweitens untersuchen wir, wie die Veröffentlichung eines offenen Briefes, der von 6.000 Wissenschaftlerinnen und Wissenschaftlern unterzeichnet wurde, die öffentliche Debatte beeinflusst haben könnte. Wir vergleichen die Rolle, die wissenschaftliche Erkenntnisse bei der Verabschiedung des NRR gespielt haben, mit dem Schicksal des SUR, welches vom Europäischen Parlament abgelehnt wurde. Diesen beiden Fällen verdeutlichen das globale Spannungsverhältnis zwischen Umweltschutz und wirtschaftlich motivierten Interessen zur Verbreitung von Fehlinformationen. Wir empfehlen, dass Wissenschaftlerinnen und Wissenschaftler eine wichtige Rolle dabei spielen sollten, der Öffentlichkeit und den politischen Entscheidungsträgern wissenschaftliche Erkenntnisse für eine fundierte Entscheidungsfindung zugänglicher und verfügbarer zu machen. Forschende sollten proaktiv und unparteiisch Informationen und Daten zur Verfügung stellen, und dass politischen Entscheidungsträger sollten wissenschaftliche Erkenntnisse nutzen und Wissenschaftlerinnen und Wissenschaftler in die Entwicklung dringend benötigter, Evidenz‐basierter Umweltpolitik einbeziehen.Halting biodiversity loss, mitigating global warming and maintaining the long‐term viability of rural and urban areas requires urgent policy action. However, environmental policies often trigger resistance and highly polarised public debates, with some actors employing pseudo‐scientific claims. This raises concern about the increasing impact of misinformation on policymaking. Here, we analyse the role of science and scientists in the public debate around two pieces of legislation that were proposed in 2022 by the European Commission as part of the Green Deal, namely the Nature Restoration Regulation (NRR) and the Sustainable Use Regulation (SUR) of plant protection products. First, we examine key claims against these two legislative proposals and contrast them with scientific evidence. We show that these claims fail to consider ample scientific evidence that restoring nature and reducing the use of agrochemicals are essential for maintaining long‐term agricultural production and enhancing food security. Critics further failed to acknowledge that the NRR and SUR may generate new employment opportunities and stimulate innovation, with high return rates and multiple beneficiaries across society, fostering a transition to sustainable production and consumption models. Second, we examine how the publication of an open letter, signed by 6000 scientists, may have influenced the public debate. We contrast the role that scientific evidence played in the fate of the NRR, which was adopted, against the fate of the SUR, which was rejected by the European Parliament. We draw lessons from these two cases that illustrate the global tension between environmental protection and economic‐driven interests to spread misinformation. We argue that scientists should play an important role in making scientific evidence more accessible and available to the general public and policymakers for informed decision‐making. We recommend that scientists be proactive and unbiased in providing information and data and that policymakers use scientific evidence and engage scientists in developing much needed, well informed environmental policies. Read the free Plain Language Summary for this article on the Journal blog.Detener la pérdida de biodiversidad, mitigar el calentamiento global y mantener la viabilidad a largo plazo de las zonas rurales y urbanas exige una actuación política urgente. Sin embargo, las políticas medioambientales a menudo generan resistencia y debates públicos muy polarizados, en los que algunos actores emplean afirmaciones pseudocientíficas. Esto suscita preocupación por el creciente impacto de la desinformación en la elaboración de políticas. Aquí analizamos el papel de la ciencia y los científicos en el debate público en torno a dos propuestas legislativos presentadas en 2022 por la Comisión Europea como parte del Pacto Verde‐ el Reglamento de Restauración de la Naturaleza (RNR) y el Reglamento de Uso Sostenible de Productos Fitosanitarios (SUR). En primer lugar, examinamos las principales alegaciones contra estas dos propuestas legislativas y las contrastamos con evidencias científicas. Demostramos que estas afirmaciones no tienen en cuenta la amplia evidencia científica de que restaurar la naturaleza y reducir el uso de productos agroquímicos son esenciales para mantener la producción agrícola a largo plazo y mejorar la seguridad alimentaria. Los críticos tampoco reconocen que la RNR y la SUR pueden generar nuevas oportunidades de empleo y estimular la innovación, con altas tasas de retorno y múltiples beneficiarios en toda la sociedad, fomentando así una transición hacia modelos sostenibles de producción y consumo. En segundo lugar, examinamos cómo la publicación de una carta abierta, firmada por 6.000 científicos, pudo haber influido en el debate público. Contrastamos el papel que jugó la evidencia científica en el destino de la RNR, que fue adoptada, frente al destino del SUR, que fue rechazado por el Parlamento Europeo. Extraemos lecciones de estos dos casos que ilustran la tensión global entre la protección del medio ambiente y los intereses económicos que impulsan la desinformación. Defendemos que los científicos deben desempeñar un papel importante y hacer que la evidencia científica sea más accesible y esté disponible tanto para el público en general como para los responsables políticos, con el fin de que tomen decisiones informadas. Recomendamos que los científicos sean proactivos e imparciales a la hora de proporcionar información y datos, y que los responsables políticos utilicen la evidencia científica e involucren a los científicos en el desarrollo de las políticas medioambientales bien informadas, que tan necesarias son
Sailing together: A review of the pelagic Sargassum microbiome
No full textInternational audiencePelagic Sargassum, denoting the two species S. natans and S. fluitans, has become a focal point of both scientific and public interest due to recent superbloom events. As a result, investigation into the dynamics of Sargassumassociated microbiota, which was previously quite limited, has regained momentum in the past five years. This review collates the current state of knowledge relating to the Sargassum microbiome as well as synthesizes relevant biogeochemical findings which may aid future efforts in this field. We explore microbiome composition and functional roles within this holobiont, specifically in terms of taxonomic diversity, macronutrient cycling, and the fate of Sargassum-derived organic matter. Despite progress, significant gaps remain in our understanding of the dynamic interactions within these microbial communities and their broader ecological significance. Future research directions are identified alongside recommendations for standardized protocols, emphasizing the need for more in-depth studies utilizing advanced molecular and biogeochemical techniques to unravel the full complexity of the Sargassum microbiome
Co-construire la science avec la société : suivi des effets à long terme du changement global sur les estrans rocheux intertidaux avec les sciences participatives
No full textInternational audienceMarine biodiversity is facing unprecedented global changes due to the phenomenon known as “Blue Acceleration,” and addressing this issue is a critical responsibility for human societies. Intertidal areas, particularly rocky shores, are especially vulnerable, as they are located at the interface between land and sea where they experience multiple anthropogenic pressures in addition to extreme variations in natural conditions. These areas are easily accessible, very frequented and deeply rooted in local culture. As such, they present a very promising opportunity to simultaneously investigate the impact of environmental change on intertidal biodiversity and engage human societies in these questions with citizen science programs.We present here the co-construction process of developing an existing citizen science program called BioLit to study the response of gastropod communities on French rocky shores to two drivers of global change (pollution and climate change) with the ESPOIRS project. This project follows a transdisciplinary ecology-sociology approach, involving citizen scientists throughout the whole scientific process with the aim of co-constructing citizen science-based bio-indicators. We implemented this process with two contrasted groups of volunteer citizens which were involved in designing and conceptualizing indicators, formulating their needs and use for such indicators, and tailoring changes in the citizen science protocol and in the sampling schemes to ensure adequate spatio-temporal monitoring effort. These choices vary between drivers of global change, as the investigation of pollution (specifically, eutrophication) requires mainly spatial planning, whereas climate change requires temporal planning. Our work presents a model of open, inclusive and non-top-down science, following a process of joint exploration, with organized meetings bringing together a diverse range of stakeholders. These carry different types of knowledge and value systems, but also different types of normativity depending on their practice, which require reconciliation through collective arbitration. Finally, we offer a reflection on the potential of this approach, rooted in real-world contexts, to promote the sustainability of marine indicators by involving citizens at every stage and simultaneously addressing challenges from data collection to indicator use. We advocate for integrative science that builds on the close interconnection between the ocean and human societies to produce knowledge on marine biodiversity, monitor its changes and enhance ecosystem protection