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Crop diversity reduces pesticide use more efficiently with refined diversification strategies
No full textInternational audiencePesticides assured food security for decades, but have left humanity with degraded soils, polluted water, and biodiversity losses. Enhanced crop diversity contributes to the regulation of insect pests, weeds, and diseases, and is therefore assumed to allow pesticide reduction. At the cropping system scale, pesticide use is affected more by crop species than by the number of crops, because crops have contrasting sensitivities to pests and contrasting pesticide requirements. Here, we disentangled the effects of diversity from the effects of crop species, for 1285 cropping systems in French commercial arable farms, using 28 indicators of functional diversity. A composite diversity metric, combining indicators with the greatest explanatory power, accounted for 8% of the pesticide use variance, much less than the variance due to crop species. The results suggest that reducing agricultural reliance on pesticides through diversification is feasible when different components of diversity—namely, crop species and diversity features—are combined
Sedimentary habitat units in public policies: habitats classifications, correlations and regulatory implications
No full textInternational audienc
Risk Assessment and Spatiotemporal Variation of Microplastic Concentration, Size, and Polymer Type in Mayotte Lagoon’s Surface Water (Comoros Archipelagos)
No full textInternational audienceThe concentration of microplastics [300–5000 µm] in the surface water of the Mayotte lagoon, Western Indian Ocean, was measured over two snapshot campaigns conducted during the dry and rainy seasons. The concentration in the surface water varied from 0.01 MP m−3 to 1.23 MP m−3 and was higher during the rainy season. All particles were analyzed via µFTIR, enabling systematic polymer and surface area determination. Polypropylene dominated over polyethylene and polystyrene, representing 70% of the microplastic particles observed. The microplastics, which were predominantly in the [0.3–1000 µm] fraction, presented a similar seasonal trend of distribution with respect to their occurrence, suggesting that turbulence and the subsequent settling of microplastics in the lagoon’s surface water were identical during the two campaigns. PCA was performed to deconvolute the effects of season and hydrodynamic features on the observed surface water concentrations and median size distribution. It evidenced a high degree of disparity in concentration and median area in surface water during the rainy season, while a lower concentration of smaller particles was observed during the end of the dry season. A microplastic risk assessment was performed for the surface water of the lagoon and evidenced a low pollution load index and low to high polymer risk assessment and potential ecological risk indexes
Interspecies synchrony in departure decisions from stopover sites: evidence using a multi‐species capture-recapture model
No full textInternational audienceDuring migration, migratory bird species often aggregate at the same stopover sites due to geographical features that channel migratory routes (coasts, valleys) or locally abundant food resources (e.g. reedbeds, fruiting bushes). In migration ecology, however, stopover behavior is often studied on a single species, limiting the generality of inferences and their application to habitat management. If stopover decisions are similar across co‐occurring species, characterizing stopover ecology at a community level could provide more comprehensive insights. Using recent advances in modelling, we adapted a multi‐species capture‐recapture model to 1) quantify synchrony in stopover departure probabilities across species and 2) identify covariates driving this synchrony. We applied this model to three migratory songbirds commonly captured at French stopover sites: the sedge warbler Acrocephalus schoenobaenu s, reed warbler Acrocephalus scirpaeus and bluethroat Luscinia svecica . Departure decisions were largely synchronous across species, with time since arrival (TSA) as the primary synchronizing factor and weather conditions as a secondary influence. High synchrony in departure timing produced waves of migrant departures and consistent patterns in departure decisions across species, suggesting shared fuelling and timing strategies. Although this phenomenon has been documented via visual counts and radar, it has not been formally quantified at the species‐level using capture‐recapture methods. Our model is flexible and can test hypotheses regarding spatial synchrony in departure decisions. With decades of capture–recapture data available across Europe and North America, our approach offers new potential for studying stopover ecology at the community level, over large geographic and temporal scales
Environmental DNA illuminates the darkness of mesophotic assemblages of fishes from West Indian Ocean
No full textInternational audienceThe advent of environmental DNA (eDNA) represents a pivotal advancement in probing mesophotic communities, offering a non-intrusive avenue for studying marine biodiversity at greater depths. Using this approach, we characterized and compared the mesophotic reef fish assemblages of two West Indian Ocean islands, Mayotte and La Réunion, which are characterized by different geo-morphological contexts. The sequences obtained were assigned taxonomically and grouped into molecular operational taxonomic units to perform richness and beta diversity analyses. The functional diversity of the assemblages was assessed using five traits, enabling each sequence to be assigned to a functional entity corresponding to a specific trait combination. On both islands, the fish assemblages exhibited a comparable level of taxonomic and functional richness, consisting mainly of piscivorous and planktivorous fishes. These assemblages were primarily composed of families such as Serranidae, consistent with expectations for the mesophotic zone. However, beta diversity analyses revealed that the two islands exhibited different taxonomic and functional structures. For example, La Réunion was characterized by a greater importance of the Muraenidae, while Mayotte displayed a higher representation of families strongly associated with coral reefs (e.g., Zanclidae or Malacanthidae). These results suggest that depth-related forcing constrains fish assemblages to some extent, but that differences in structure remains determined by other, more local factors, likely linked to the geo-morphological contexts of the islands and their habitats. This study also revealed that eDNA is a promising method for studying difficult-to-observe taxa, such as moray eels or lanternfish, and may also be relevant for monitoring species depth ranges. Overall, results highlighted the “local scale”, “functionally integrative” and “temporally integrative” characteristics of eDNA for studying mesophotic reef fish assemblages. However, this study also highlights the limitations of reference DNA databases, pointing to future prospects for fully exploiting the potential of eDNA approaches in the mesophotic zones of the Indian Ocean
Indicateur Hydromorphologique résultant de la méthode Carhyce ou IHC : pour l'évaluation intégratrice et multiparamétrique du fonctionnement physique des cours d’eau. Programme Carhyce IV - Rapport scientifique et technique final
No full textSubsidies against Nature: A multidimensional framework for biodiversity-aligned national budgets
No full textInternational audienceGovernments provide more than USD 800 billion annually in environmentally harmful subsidies at the global level despite international commitments. This paper introduces a novel and replicable framework for identifying biodiversity-harmful subsidies within national budgets. Our multidimensional approach is based on the five drivers of biodiversity loss: land use change, resource exploitation, climate change, pollution, and invasive species. Our framework evaluates subsidies across seven economic sectorstransport, housing, industry, agriculture, livestock, power generation, and digital deployment-based on their expected biodiversity impact (harmful, positive, mixed, neutral, or unclassifiable). We apply this framework to the French national budget and find that, in 2022, €27.14 billion were allocated to subsidize harmful activities. Pollution is the most financially supported driver of biodiversity loss. Our analysis also reveals significant trade-offs, with 25% of climate-positive subsidies exacerbating land use pressures. The study calls for a sector-specific approach to subsidy reform. By codeveloping this framework with biodiversity experts and public authorities, we provide a decision-support tool to align public investments with pathways towards sustainability
Pratiquer la cohabitation : analyse des modes interrelations entre biodiversité et sportifs dans le cadre de la pratique du trail
No full textProjet suivi par Julien GautheyLe projet de recherche et développement s’est notamment concrétisé à travers une recherche doctorale dont la thèse a été soutenue publiquement le 11 juillet 2024 au laboratoire Environnement et Dynamique des Territoires de Montagne (Edytem ; UMR 5204) à l’université Savoie Mont-Blanc. Ce rapport repose essentiellement sur les matériaux ainsi que les analyses menées pendant cette recherche doctorale. D’après l’Enquête Nationale sur les Pratiques Physiques et Sportives (ENPPS) menée par le ministère chargé des sports et l’Institut National de la Jeunesse et de l’Education Populaire auprès de 12 000 répondants, la pratique du trail réunit en 2020 plus d’un million de pratiquants en France. Cette pratique sportive se retrouve sur l’ensemble du territoire français et au-delà.Elle ne se limite ni au terrain montagnard, ni au temps des vacances ou aux espaces des courses organisées. À l’aune de cette recherche nous pouvons avancer que la pratique du trail est une activité diffuse dans le temps et dans l’espace dont la diversité des formes est d’une brûlante actualité. Elle pourrait se définir très sommairement par le fait de courir sur des sentiers comme l’anglicisme ‘trail’ utilisé pour la nommer le suggère.L’ensemble des recherches menées dans ce projet s’est concentré sur cette seule pratique. Le choix de cette focale resserrée a permis de capter les nuances d’engagement des sportifs et la diversité de leurs expériences. In fine, ce projet s’est attaché à récolter et analyser des matériaux qualitatifs pour rendre compte des rapports des traileurs à leurs environnements de pratique dans une approche compréhensive complémentaire à des approches quantitatives
Évolution de l'épidémiologie des virus de l'influenza aviaire hautement pathogene chez les oiseaux sauvages depuis 2020 : une revue de la litterature
No full textInternational audienceLes virus de l'influenza aviaire hautement pathogène (IAHP), en particulier les virus H5 du clade 2.3.4.4b, ont causé des épizooties dévastatrices chez les oiseaux sauvages et domestiques ainsi que des transmissions significatives aux mammifères, particulièrement depuis 2020. Notre étude cherche à comprendre le rôle des oiseaux sauvages dans la transmission et la propagation des virus IAHP entre 2020 et 2023 à l'échelle mondiale. En analysant la littérature existante et les cas déclarés chez les oiseaux sauvages dans le monde, nous montrons que les populations sauvages ont fortement contribué à la circulation de ces virus. De nombreuses espèces d'oiseaux sauvages sont impactées, à une échelle mondiale et dans certains cas de manière massive. Certaines espèces d'anatidés, notamment des canards et des oies, sont souvent mentionnées pour leur rôle dans la diffusion des virus via des mouvements migratoires. Ce travail souligne l'importance de poursuivre les recherches et la collaboration afin d'atténuer les impacts de ce virus sur la santé animale et humaine
Updated global conservation status and priorities for marine turtles
No full textInternational audienceAssessing conservation status and pursuing applicable management priorities for marine megafauna across multiple scales pose significant challenges. Because marine turtles exemplify these challenges, the IUCN Marine Turtle Specialist Group (MTSG) developed the ‘conservation priorities portfolio’ (CPP) framework in 2011 to evaluate population risk and threats for regional management units (RMUs). Here, the MTSG has updated the 2011 CPP framework through an inclusive assessment process. Expert elicitation results involving 145 individuals from 50 countries suggests that marine turtle conservation status appears to be improving, but significant challenges remain. Since the previous assessment, long-term abundance trends increased on average, and threat impact scores improved for nearly twice as many RMUs (53%) as worsened (28%) (≥10% threshold for changes in numeric scores). While expert-assessed threat impacts have generally decreased, fisheries bycatch remains the highest scored threat across regions and species. Risk-threat staus improved for most (54%) RMUs. Over 40% of RMUs were scored as low risk-low threats, of which 8 were green turtles Chelonia mydas RMUs. Less than 20% of RMUs were scored as high risk-high threats, of which 4 were leatherback turtles Dermochelys coriacea . Most high risk-high threats RMUs were in the Pacific Ocean, while most low risk-low threats RMUs were in the Atlantic Ocean. Eleven RMUs were evaluated as having critical data needs. Our results—also provided through an interactive data dashboard—underscore the importance of context-specific planning to effectively target limited conservation resources. Future assessments should further prioritize inclusion of under-represented topics, researchers, and regions to better address multi-faceted conservation challenges.Évaluer l’état de conservation et définir les priorités de gestion appropriées pour la mégafaune marine à différentes échelles représente un défi majeur. Les tortues marines illustrant bien ces difficultés, le Groupe de spécialistes des tortues marines de l’UICN (MTSG) a développé en 2011 le cadre « *Conservation Priorities Portfolio* » (CPP) pour évaluer les risques pesant sur les populations et les menaces au sein des unités de gestion régionales (RMU). Le MTSG a mis à jour ce cadre en 2023 à travers un processus d’évaluation inclusif. Les résultats d'une consultation d'experts impliquant 145 personnes de 50 pays suggèrent que l’état de conservation des tortues marines semble s’améliorer, bien que d’importants défis subsistent. Depuis la précédente évaluation, les tendances d’abondance à long terme se sont améliorées en moyenne, et les scores d’impact des menaces se sont améliorés pour presque deux fois plus de RMUs (53 %) qu’ils ne se sont dégradés (28 %) (seuil de variation ≥10 % dans les scores numériques). Bien que les impacts des menaces, selon les experts, aient globalement diminué, les prises accessoires dans les pêcheries demeurent la menace la plus importante toutes régions et espèces confondues. Le statut risque-menace s’est amélioré pour la majorité (54 %) des RMUs. Plus de 40 % des RMUs ont été classées à faible risque-faible menace, dont 8 concernaient des populations de tortue verte (*Chelonia mydas*). Moins de 20 % des RMUs ont été classées à haut risque-haute menace, dont 4 étaient des populations de tortue luth (*Dermochelys coriacea*). La majorité des RMUs à haut risque-haute menace se trouvent dans l’océan Pacifique, tandis que la plupart des RMUs à faible risque-faible menace sont situées dans l’océan Atlantique. Onze RMUs ont été évaluées comme nécessitant des données critiques. Nos résultats — également disponibles via un tableau de bord interactif — soulignent l’importance d’une planification spécifique au contexte pour cibler efficacement les ressources de conservation limitées. Les futures évaluations devront inclure davantage de thématiques, de chercheurs et de régions sous-représentés afin de mieux relever les défis complexes de la conservation