ALBERT

Description: Aims Zoochory is a prominent dispersal process in a wide range of plant species. However, the extent to which the trait composition of dispersed seed assemblages differs from the regional assemblage remains untested, as does the extent to which sympatric native herbivores disperse traits non-randomly. Location Lorris and Montargis forests, central France. Methods We compared the taxonomic and functional composition of seed assemblages dispersed by three wild ungulates to the characteristics of the regional flora in an agro-forested landscape. We collected roe deer ( Capreolus capreolus ), red deer ( Cervus elaphus ) and wild boar ( Sus scrofa ) faeces in two forests, and subjected the samples to germination under controlled conditions. We first examined how different vectors influence the composition of the dispersed plant assemblages by comparing abundance and species richness of the seedlings emerging from the faeces of the three ungulates. We then compared the functional characteristics of the dispersed pool with those of the regional flora in a multivariate functional space built from 20 relevant plant traits. Results A total of 754 seedlings and 46 plant species germinated from 300 faeces samples, with higher plant species richness and abundance for red deer faeces. All three ungulates widely use forest habitat, but the proportion of non-forest plants was higher in red deer and wild boar faeces than in the regional species pool. Traits such as seed shape, seed size or seed bank longevity affected dispersal probability, but their effects were overshadowed by habitat effects. Conclusions Endozoochory acts as an indirect functional filter, filtering species according to the vectors' feeding habitat. This could affect the composition of forest plant communities by allowing plants from open habitats to colonize forested areas. A seedling of Chenopodium album that germinated in faeces. Photo © Mélanie Picard. We tackle here a plant-animal interaction overlooked in plant community dynamics. We compared the functional traits of plants dispersed by three native ungulates through endozoochory to those of the regional flora. We show that endozoochory applies a biotic filter on plant community through vector's feeding habitat preferences, allowing plants from open habitats to colonize forested areas.

Description: Abstract The effects of climate change, including ocean acidification and ocean heatwaves, on biological communities in estuaries are often uncertain. Part of the uncertainty is due to the complex suite of environmental factors in addition to acidification and warming that influence the growth of shells and skeletons of many estuarine organisms. The goal of this study was to document spatial and temporal variation in water column properties and to measure the in situ effects on larval and recently settled stages of ecologically important Olympia oysters (Ostrea lurida) and commercially important Pacific oysters (Crassostrea gigas) in a low‐inflow estuary with a Mediterranean climate in Northern California. Our results reveal that seasonal inputs of upwelled or riverine water create important and predictable gradients of carbonate system parameters, temperature, salinity, dissolved oxygen (DO), and other variables that influence oyster performance, and that the influence of these gradients is contingent upon the location in the estuary as well as seasonal timing. During upwelling events (dry season), temperature, carbonate chemistry, and DO had the greatest impact on oyster performance. During runoff events (wet season), gradients in salinity, nutrient concentrations, and total alkalinity driven by river discharge were comparatively more important. These results suggest that the spatial importance of carbonate chemistry and temperature are seasonally variable and are two of several other factors that determine oyster performance. We use these results to discuss future impacts on oysters given projected regional changes in the frequency and magnitude of upwelling and precipitation‐driven runoff events.

Description: This study reports precise and accurate data for rare earth elements (REE) measured on eight geological reference materials, five enriched in REE (BE-N, BHVO-2, BR, BR-24 and RGM-1) and three very depleted in REE (BIR-1, UB-N and DTS-2). Data were acquired by quadrupole ICP-MS after isolation of the REE using an ion-exchange chromatography procedure. All the measured REE abundances were similar within ≈ 5% (10% for the most REE-depleted sample DTS-2) to the high-quality measurements previously published in the literature. We also show that by using an internal Tm spike, the reproducibility of the data was improved to ∼ 1%. Applying this technique to the analysis of ultra-depleted rock samples (sub ng g −1 ), we show that significant improvements were obtained relative to the routine trace element measurement method. The chondrite-normalised patterns were smooth instead of displaying irregularities. Although the classical method gives excellent results on REE-rich samples, we believe that our technique improves the precision and accuracy of measurements for highly REE-depleted rocks. Cette étude présente des données de terres rares (REE) précises, mesurées sur huit matériaux géologiques de référence, cinq enrichis en terres rares (BE-N, BHVO-2, BR, BR-24 et RGM-1) et trois très appauvris en REE (BIR-1, UB-N et DTS-2). Les données ont été acquises par ICP-MS quadripolaire après isolement des terres rares par l’utilisatiion d’une procédure chromatographie échangeuse d’ions. Toutes les abondances mesurées de terres rares ont été similaires, à environ ≈ 5% près (10% pour l’échantillon le plus appauvri en REE, DTS-2), aux mesures de haute qualité issues de la littérature. Nous montrons également que l’utilisation d’un ajout («spike») interne de Tm a permit d’améliorer la reproductibilité des données d’environ 1%. En appliquant cette technique à l’analyse d’échantillons de roches ultra-appauvris (au niveau du ng g −1 ), nous montrons que des améliorations significatives ont été obtenues par rapport à la méthode de routine de mesure des éléments traces. Les spectres normalisés aux chondrites sont lisses au lieu d’afficher des irrégularités. Bien que la méthode classique donne d’excellents résultats pour des échantillons riches en terres rares, nous croyons que notre technique améliore la précision et l’exactitude des mesures pour les roches très appauvris en terres rares.

Description: Dispersal is a key process in metapopulation dynamics as it conditions species' spatial responses to gradients of abiotic and biotic conditions and triggers individual and gene flows. In the numerous plants that are dispersed through seed consumption by herbivores (endozoochory), the distance and effectiveness of dispersal is determined by the combined effects of seed retention time in the vector's digestive system, the spatial extent of its movements, and the ability of the seeds to germinate once released. Estimating these three parameters from experimental data is therefore crucial to calibrate mechanistic metacommunity models of plant–herbivore interactions. In this study, we jointly estimated the retention time and germination probability of six herbaceous plants transported by roe deer ( Capreolus capreolus ), red deer ( Cervus elaphus ), and wild boar ( Sus scrofa ) through feeding experiments and a Bayesian dynamic model. Retention time was longer in the nonruminant wild boar (〉36 h) than in the two ruminant species (roe deer: 18–36 h, red deer: 3–36 h). In the two ruminants, but not in wild boar, small and round seeds were excreted faster than large ones. Low germination probabilities of the excreted seeds reflected the high cost imposed by endozoochory on plant survival. Trait-mediated variations in retention time and germination probability among animal and plant species may impact plant dispersal distances and interact with biotic and abiotic conditions at the release site to shape the spatial patterns of dispersed plant species. We quantify seed retention time and germination probability after release by ungulates to test whether endozoochorous dispersal depends on plant and vector functional traits. For this, we calibrate a bayesian dynamic model using experimental data from individual monitoring. We show that seed retention time and germination probability vary according to seed and animal traits. Our model can be applied to further plant-animal systems and used to calibrate time-distance functions in dispersal models.

Description: This study reports precise and accurate data for rare earth elements (REE) measured on eight geological reference materials, five enriched in REE (BE-N, BHVO-2, BR, BR-24 and RGM-1) and three very depleted in REE (BIR-1, UB-N and DTS-2). Data were acquired by quadrupole ICP-MS after isolation of the REE using an ion-exchange chromatography procedure. All the measured REE abundances were similar within ≈ 5% (10% for the most REE-depleted sample DTS-2) to the high-quality measurements previously published in the literature. We also show that by using an internal Tm spike, the reproducibility of the data was improved to ∼ 1%. Applying this technique to the analysis of ultra-depleted rock samples (sub ng g −1 ), we show that significant improvements were obtained relative to the routine trace element measurement method. The chondrite-normalised patterns were smooth instead of displaying irregularities. Although the classical method gives excellent results on REE-rich samples, we believe that our technique improves the precision and accuracy of measurements for highly REE-depleted rocks. Cette étude présente des données de terres rares (REE) précises, mesurées sur huit matériaux géologiques de référence, cinq enrichis en terres rares (BE-N, BHVO-2, BR, BR-24 et RGM-1) et trois très appauvris en REE (BIR-1, UB-N et DTS-2). Les données ont été acquises par ICP-MS quadripolaire après isolement des terres rares par l’utilisatiion d’une procédure chromatographie échangeuse d’ions. Toutes les abondances mesurées de terres rares ont été similaires, à environ ≈ 5% près (10% pour l’échantillon le plus appauvri en REE, DTS-2), aux mesures de haute qualité issues de la littérature. Nous montrons également que l’utilisation d’un ajout («spike») interne de Tm a permit d’améliorer la reproductibilité des données d’environ 1%. En appliquant cette technique à l’analyse d’échantillons de roches ultra-appauvris (au niveau du ng g −1 ), nous montrons que des améliorations significatives ont été obtenues par rapport à la méthode de routine de mesure des éléments traces. Les spectres normalisés aux chondrites sont lisses au lieu d’afficher des irrégularités. Bien que la méthode classique donne d’excellents résultats pour des échantillons riches en terres rares, nous croyons que notre technique améliore la précision et l’exactitude des mesures pour les roches très appauvris en terres rares.