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Better out than in: faecal matrix inhibits establishment success after waterfowl endozoochory
No full textInternational audienceAbstract Background and Aims Many plant species undergo long-distance dispersal through migratory waterbirds. However, there is little information about the effectiveness of this dispersal, especially regarding the chances of plant establishment and the impact of gut passage or the faecal matrix on plant germination, growth and reproductive investment in seeds. Methods In a greenhouse experiment, we addressed these questions using an annual mudflat species, Juncus bufonius (Juncaceae), and a perennial emergent aquatic species, Eleocharis palustris (Cyperaceae), whose seeds are dispersed by many waterbird species in Europe. We planted seeds directly in soil or within mallard faeces placed on soil, using both control seeds and seeds that survived gut passage through mallards. Over the following 11 weeks, we quantified germination and plant performance. Key Results Gut passage reduced germination time of J. bufonius when there was no faecal matrix, and it increased asymptotic height of E. palustris. Presence of the faecal matrix hindered germinability, plant growth and final biomass for both species, along with total seed production for J. bufonius. Presence of the faecal matrix slowed down germination in E. palustris, but had the opposite effect for J. bufonius. It was also associated with greater relative investment in seeds in J. bufonius (more seeds per unit biomass), probably as a consequence of later germination. In both species, earlier germination increased final biomass (and seed production in J. bufonius). Conclusions Our results support the importance of waterbird endozoochory in plant dispersal but suggest that it might be more effective when faeces disintegrate, such as when egested into water or disaggregated on land (e.g. by insects). Previous studies with other plants have recorded accelerated germination following waterbird gut passage, and our results show that this can benefit plant fitness
Chapitre 6. Facteurs morpho-phonologiques influant sur la désaccentuation en japonais de Tokyo moderne
No full textInternational audienceCet article porte sur la désaccentuation en japonais de Tōkyō moderne, une tendance accentuelle en cours d’évolution. Dans un premier temps, il expose les bases du système accentuel et décrit le phénomène de désaccentuation, en soulignant certains facteurs morpho-phonologiques qui y sont liés, ainsi que la méthodologie adoptée. La seconde partie analyse les résultats à travers quatre paramètres principaux : la longueur des mots, la position originelle du noyau accentuel, la structure morique et la structure morphologique. La combinaison de ces paramètres permet d’identifier une forme canonique de la désaccentuation. Enfin, la discussion et la conclusion mettent en perspective ces résultats, en proposant de nouvelles pistes de recherche sur l’accent en japonais de Tōkyō moderne
Litter in French urban areas — Part 2: transport dynamic and fluxes in stormwater
No full textInternational audienceUrban areas constitute a major hotspot of litter, including plastic litter, that stormwater can wash off towards waterways. However, few studies quantified and characterized litter densities in urban areas and fluxes transported by stormwater networks. Moreover, little information is available on litter transport dynamics in stormwater, and on the factors driving this transport. This study aims at characterizing and quantifying litter amounts transported by stormwater of two nested French urban catchments (total surface area of 105 ha). Litter densities relative to land uses and rain events were investigated in the same catchments as in a compagnon paper (Ledieu et al., 2024). The present study explores the impact of rain events on the transport of urban litter in stormwater. Litter collection and characterization combined with a capture/recapture experiment using tagged litter placed in stormwater inlets show total litter fluxes of 29 kg/year, in which 14 kg/year are plastics, exported at the stormwater outlet. These fluxes confirm that stormwater runoff is a considerable pathway from urban surfaces to waterways, especially regarding small plastic litter (< 2.5 cm). Item transport dynamic is however not linear and only 0.3% of the urban litter appear remobilized. Litter transport dynamics depends on several factors (urban litter densities, hydrometeorological parameters, item composition and morphologies, and stormwater management systems) that should be considered in global models
Base de données des morphèmes sino-japonais d’une unité morphophonologique, à caractère nominal; kunc-bd-v1.0.0
No full textDocumentation de la base de données kunc-bd-1.0.0Description du contenu de la base de données "Base de données des morphèmes sino-japonais d’une unité morphophonologique, à caractère nominalkunc-bd-v1.0.0
POD-Galerkin reduced order model coupled with neural networks to solve flow in porous media
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Intrinsic and extrinsic drivers of juvenile survival in emperor penguins
No full textInternational audienceOur understanding of demographic processes is mainly based on the analysis of the adult components of populations. However, juvenile survival is decisive for recruitment, and therefore for the dynamics of populations. Our study aims at understanding the environmental determinants of juvenile survival in the emperor penguin, a species for which this critical phase is poorly known. We used capture-mark-recapture models to leverage 13-years of electronic monitoring of birds tagged as fledglings at Pointe Géologie, Adélie Land. Emperor penguin juvenile survival showed very high interannual variability (0.08 to 0.48), a pattern no longer observed in immatures and adults. Furthermore, we emphasized the importance of body mass on juvenile survival, and which was tightly associated with sea ice extent during the chick rearing period. We also showed that oceanographic conditions (width of the polar front) during the first weeks after fledging are an important predictor of juvenile survival. Our results suggest that the conditions of accessibility and abundance of food resources during this phase of learning to swim and dive play a crucial role in the survival of young penguins. Finally, our study provides new insights into sex-specific differences in survival in this species, which seems to emerge only in adulthood
L’évolution de l’administration des douanes aux frontières maritimes : le cas de la Vendée (1905-1945)
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Local climate change action plans in France: between formal compliance and grassroots appropriation
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Towards a comprehensive view of wetland benthic communities
No full textInternational audienceBenthic prokaryotic communities, utmost important for wetlands and marine environments functioning, are influenced by physical-chemical parameters and interactions with other communities, especially micro-eukaryotes and meiofauna. Thus, a holistic view of the benthic community is necessary to fully understand their organization and functioning. This study assesses the implementation of a comprehensive view, using mock communities and environmental samples. A DNA extraction strategy combining two procedures is proposed: one to obtain DNA from micro-organisms, using 0.25 g of sediment, and the other from meiofauna, using 0.25 g of sieving refluxes from 5 g of sediment. Three conditions were considered to create mock communities: (i) varying eukaryotes’ abundance, (ii) adding meiofauna from salted or freshwater wetlands, and (iii) including or not a sediment matrix. Most organisms composing the mock communities were detected, except a filamentous cyanobacteria. All mock communities showed similar composition indicating that sediment did not affect the DNA extraction. This result also demonstrated that sieving, necessary to enrich meiofauna from sediment, does not significantly affect any of the communities. For the environmental samples investigated, most of the taxa usually described in the literature were retrieved in the salted, brackish and freshwater marshes sediment. The proposed approach was successful in analysing organisms from the three domains of life in a unique environmental sample, providing a holistic view of the benthic community. Furthermore, the significant differences observed between samples from the three different marshes, indicated that our approach can be used for conducting successful ecological studies, especially useful for understanding benthic communities’ interactions