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International audience; Agricultural soils are exposed to multiple contaminants through the use of agrochemicals or sewage sludge, introducing metals, nanomaterials and others. Among nanomaterials, carbon nanotubes (CNTs) are known for their large surface area and adsorption capabilities, possibly modifying other element behavior. However, to date, very little is known about the impacts of such interactions in agrosystems. In this study, we aimed at understanding the transfer and toxicity of contaminants (Cd, Pb, Zn and CNTs) in microcosms including native soil bacteria, earthworms and lettuce. After a 6 week exposure, no effect of the addition of CNTs to metal contaminated soils was detected on bacterial concentration or earthworm growth. However, in lettuce, an interactive effect between CNTs and metals was highlighted: in the soil containing the highest metal concentrations the addition of 0.1 mg kg−1 CNTs led to a biomass loss (−22%) and a flavonoid concentration increase (+27%). In parallel, the addition of CNTs led to differential impacts on elemental uptake in lettuce leaves possibly related to the soil organic matter content. For earthworms, the addition of 10 mg kg−1 CNTs resulted in an increased body elemental transfer in the soil with the higher organic matter content (Pb: + 34% and Zn: + 25%).

International audience; In forested headwater streams, inconspicuous food resources such as epilithic microalgae can play a major role owing to their content of long chain polyunsaturated fatty acids (PUFAs) that are essential for macroinvertebrate development. Yet, the use of these resources and their consequences for consumers and life-history traits remain scarcely studied, especially for non-herbivorous taxa. Using instream mesocosms, we aimed to understand how two macroinvertebrate species, a shredder detritivore (Gammarus pulex) and a scraper (Rhithrogena semicolorata), use available organic resources under light versus shaded conditions (high and low amounts of phototrophic biofilm, respectively). We specifically focused on the origin of carbon (C) and essential lipids (PUFAs, sterols) assimilated by the two species and the effects of these compounds on their survival and growth. When autotrophic biofilms were available (mesocosms exposed to light), both species experienced significantly higher growth than in mesocosms placed in the dark. In Rhithrogena nymphs, the survival and imago emergence rates were positively affected by access to autotrophic biofilms. Using stable isotope analysis (δ13C and δ15N), we demonstrated that under dark conditions both macroinvertebrates assimilated C of detrital origin. Under light conditions, most of the C assimilated by R. semicolorata was derived from autotrophic biofilms and around 11% from fine detrital particles (FPOM). Gammarus pulex derived part of its C from detrital sources (mainly FPOM) and from autotrophic biofilms. The results of isotopic analyses (δ13C) on fatty acids (FAs) and sterols showed that the scraper Rhithrogena was entirely dependent on autotrophic biofilms to meet its dietary FAs and sterol requirements. In contrast, detrital sources were quantitatively important for G. pulex both in terms of C and sterol supply, irrespective of the conditions tested. For these consumers, microalgae seemed to be a complementary food source, but yet essential to cover a large part of their requirements in long-chain PUFAs. This study clearly confirmed the ecological importance of autotrophic biofilms for two functional feeding groups of macroinvertebrates in headwater streams providing new insights on the trophic origin of sterols and long-chain PUFAs in their diet.

International audience

Background The Black Soldier Fly (BSF) Hermetia illucens is a cosmopolitan fly massively used by industrial companies to reduce biowaste and produce protein and fat for poultry and aquaculture feed. However, the natural history and the genetic diversity of the BSF are poorly known. Here, we present a comprehensive phylogeny and time tree based on a large dataset of complete mitochondrial genomes better to understand the evolution and timing of the BSF. Results In this study, we analyzed 677 CO1 sequences derived from samples found all over the five continents, leading us to discover 52 haplotypes, including ten major haplotypes. This worldwide cryptic genetic and genomic diversity is mirrored at a local scale in France, in which we found five major haplotypes sometimes in sympatry. Phylogenetic analyses of 60 complete mitochondrial genomes robustly resolved the phylogeny of the major BSF haplotypes. We estimate the separation events of the different haplotypes at more than 2 million years for the oldest branches characterizing the ancestral split between present North American lineages and the other highly diverse south-central American clades, possibly the following radiation beyond the isthmus of Panama northwards. Our data confirm that this North American lineage ultimately gave birth to almost all commercial BSF stocks that participated in the worldwide BSF dissemination through farm escapements. Conclusions Our data resolve the phylogenetic relationships between the major lineages and give insights into the BSF’s short and long-term evolution. Our results indicate that commercial BSF stock’s genetic and genomic diversity is very low. These results call for a better understanding of the genomic diversity of the BSF to unravel possible specific adaptations of the different lineages for industrial needs and to initiate the selection process.

International audience; The spontaneous vegetation in vineyards is diverse and occupies an important spatial and temporal place. This vegetation is impacted by the different soil management practices and the pedoclimatic diversity of the vineyard terroirs. Its management is thought out according to the agronomic objectives of yield and quality, notably to limit competition with the vine. This management also responds to other ecological challenges: reduction in the use of herbicides, reduction in fossil fuel consumption, and the agro-ecological transition of winegrowing systems. In the "mixed" management method, which is often used, weed management in the inter-row is mainly based on mechanical weeding and/or grassing with mowing, while weeding in the row uses a chemical herbicide. In 2016, in France, inter-row weed control, whether partial or total, concerns 52% of the national vineyard area and varies greatly depending on the risk of drought and the density of plantation, which are decisive factors in the establishment and management of seeded cover. Among the many services, often linked to soil quality, potentially provided by these sown cover crops called service crops is the reduction of weeds by limiting their growth and development and inhibiting their germination. Finally, the management of spontaneous biodiversity within plots can satisfy other services such as the production of floral resources for pollinators or the production of biomass for grazing.; La flore des parcelles viticoles est diverse et occupe une place spatiale et temporelle importante dans les vignobles ; elle varie selon les pratiques d'entretien du sol et le pédoclimat. La gestion de cette flore est déterminée selon des objectifs de rendement et de qualité, et également des enjeux écologiques (herbicides, énergie fossile, et transition agroécologique). Aujourd'hui, la gestion des adventices repose majoritairement sur le désherbage mécanique et/ou l'enherbement avec tonte dans l'inter-rang, et le désherbage du rang utilise un herbicide chimique. En 2016, en France, l'enherbement sur l'inter-rang concerne la moitié du vignoble national et varie suivant le risque de sécheresse et la densité de plantation. Les cultures de services rendent de multiples services, dont la réduction des adventices. Enfin la gestion des adventices en parcelles viticoles peut fournir des services en relation avec la biodiversité (production de ressources florales pour les pollinisateurs ou de ressources fourragères).

In recent years, the desire to exploit marine renewable energies has grown and offshore construction projects have multiplied. The electricity produced is transported to the coast by a network of underwater cables generally buried in the sediment. However, these cables emit high intensity alternative AC or direct DC magnetic fields (up to 30 times higher than the geomagnetic field), whose potential effects on marine fauna are still poorly understood. Many marine organisms use the Earth's magnetic field to guide their movements at small and large scale. In this context, the objective of this thesis was to explore the behavioral responses of benthic organisms when exposed to magnetic fields of similar intensity to those theoretically emitted by submarine cables. According to a multi-model approach targeting various taxonomic groups, experiments were conducted in a controlled environment on the thornback ray Raja clavata, the velvet crab Necora puber, the blue mussel Mytilus edulis and the razor clam Ensis magnus. Artificial magnetic fields were emitted thanks to a device, named the Magnotron, based on the principle of Helmholtz coils, with computer monitoring allowing the control of the generated intensities. Behaviors of high ecological value were studied: camouflage behavior in rays, sheltering, feeding and movement behaviors in velvet crabs, filtration and bioturbation activities in mussels and razor clams, respectively. Overall, exposures to artificial magnetic fields did not cause significant behavioral changes in any of the four species. Present work is the first to evaluate magneto-sensitivity in bivalve mollusks and provides valuable data for future research. It is now necessary to evaluate the effects of medium and long term exposures and to explore the sensitivity of young life stages., Ces dernières années, la volonté d’exploiter les énergies marines renouvelables s’est renforcée et les projets de construction en haute mer se multiplient. L’électricité ainsi produite est acheminée jusqu’à la côte par un réseau de câbles sous-marins généralement enfouis dans le sédiment. Or, ces derniers émettent des champs magnétiques alternatifs AC ou continus DC d’intensité élevée (jusqu’à 30 fois supérieure au champ géomagnétique), dont les effets potentiels sur la faune marine sont encore mal connus. De nombreux organismes marins utilisent en effet le champ magnétique terrestre pour orienter leur déplacement à petite et large-échelle. Dans ce contexte, cette thèse avait pour objectif d’explorer les réponses comportementales d’organismes benthiques, lors d’exposition à des champs magnétiques d’intensités similaires à celles théoriquement émises par les câbles sous-marins. Selon une approche multi-modèles ciblant des groupes taxonomiques variés, les expérimentations ont été menées en milieu contrôlé, sur la raie bouclée Raja clavata, l’étrille Necora puber, la moule bleue Mytilus edulis et le couteau arqué Ensis magnus. Les champs magnétiques artificiels ont été émis grâce à un dispositif, surnommé le Magnotron, basé sur le principe des bobines de Helmholtz et couplé à une interface numérique permettant le contrôle des intensités générées. Des comportements à forte valeur écologique ont été étudiés : chez la raie le comportement de camouflage, chez l’étrille les comportements de mise à l’abri, d’alimentation et de déplacements et chez la moule et le couteau, les activités de filtration et de bioturbation, respectivement. De manière générale, les expositions aux champs magnétiques artificiels n’ont pas causé de changements comportementaux significatifs chez aucune des quatre espèces. Ces travaux de thèse sont les premiers à évaluer la magnéto-sensibilité des mollusques bivalves et fournissent des données précieuses pour de futures recherches. Il est maintenant nécessaire d’évaluer les effets d’expositions de moyenne et longue-durée et d’explorer la sensibilité des jeunes stades de vie.

International audience; The climate emergency makes us review our societal models, particularly in development and consumption. In the construction sector, which is one of the most impacting, a solution to fight against global warming could be to use a mix of natural, bio-sourced, or geo-sourced materials produced locally to build comfortable, healthy, and sustainable buildings. This study is devoted to two noble representatives of the category: natural limestone and wood fiber. Experimental results obtained from the instrumentation of wall samples will be compared with numerical simulations to analyze the coupled heat and moisture transfers and the relevance of the models for this type of material. The second part will present the environmental analysis of several natural stone masonries to determine the main contributing flows of the impact.; L'urgence climatique nous pousse à revoir nos modèles sociétaux, notamment en matière de développement et de consommation. Dans le secteur de la construction, qui est l'un des plus impactant, une solution pour lutter contre le réchauffement global pourrait être d'utiliser une mixité de matériaux naturels, bio-sourcés ou géo-sourcés produits localement pour bâtir des habitats confortables, sains et durables. Cette étude est consacrée à deux nobles représentants de la catégorie, que sont la pierre naturelle calcaire et la fibre de bois. Les résultats expérimentaux issus de l'instrumentation d'échantillons de parois seront confrontés à des simulations numériques afin d'analyser les transferts couplés de chaleur et d'humidité et la pertinence des modèles pour ce type de matériaux. Une seconde partie présentera l'analyse environnementale de plusieurs maçonneries en pierres naturelles dans le but de déterminer les principaux flux contributeurs de l'impact.

Characterizing the trophic ecology of sharks is fundamental to understand the potential cascading effects of their current décline in marine ecosystems. This thesis investigates the trophic niches of shark species in Coastal and offshore ecosystems around Baja California Sur (Mexico) in both the Pacific Ocean and the Gulf of California, a region characterized by a strong pressure from artisanal fisheries. Ecologically, the guiding thread was to elucidate the importance of resource partitioning in shaping shark realized trophic niches, at both the intra- and inter-specific level. To achieve this objective, multiple trophic biomarkers were used, such as carbon, nitrogen and mercury stable isotopes, and fatty acid compositions, to describe the vertical and horizontal dimensions of shark foraging habits.At the intra-specific level, resource partitioning was supported by the use of distinct ecosystems for juvenile hammerhead sharks due to ontogenetic shifts in habitat and prey. Inter-specific resource partitioning seems to be driven by foraging at different depth within pelagic assemblages, but could also depend on local environmental conditions, such as upwelling activity. This work also characterized the life cycle of a poorly studied hammerhead species, the smooth hammerhead shark (Sphyrna zygaena). The prolonged Coastal residency of this species through ontogeny suggests significant vulnerability to local artisanal fisheries. Finallly, the demonstrated complementarity of trophic markers provides a promising insight to unravel food web structure and ecological mechanisms.; Décrire la niche trophique occupée par les requins est fondamental dans la compréhension du contrôle trophique qu'ils exercent sur les communautés associées et des potentielles conséquences de leur surpêche sur le milieu marin. Dans cette thèse, l'habitat alimentaire de différentes espèces de requins a été étudié le long des côtes de Basse Californie du Sud (Mexique), une région où la pression de pêche sur ces prédateurs est forte. D’un point de vue écologique, l’idée directrice était de décrire l’importance de la répartition de la ressource dans la définition des niches trophiques à l’échelle intra- et inter-spécifique. Pour cela, plusieurs outils ont été utilisés tels que les isotopes stables du carbone, de l’azote et du mercure, ainsi que la composition en acides gras permettant la description verticale et horizontale des habitats alimentaires. À l’échelle intra-spécifique, la répartition de la ressource chez les requins marteaux juvéniles est liée à l’utilisation d’écosystèmes et de proies distincts au cours de la croissance. À l’échelle inter spécifique, elle s’exprime par des différences de profondeur d’alimentation au sein des assemblages pélagiques, mais dépend aussi des conditions environnementales telles que la présence d’upwelling. Ce travail a également conduit à une meilleure caractérisation du cycle de vie du requin marteau commun (Sphyrna zygaena), démontrant ainsi une vulnérabilité accrue aux pressions de pêche liée à une résidence prolongée en milieu côtier. Finalement, la complémentarité des marqueurs trophiques utilisés offre de prometteuses perspectives quant à l’étude des réseaux alimentaires.

International audience

International audience; Because of land use changes, a worldwide decrease in biodiversity is underway, mostly driven by habitat degradation and fragmentation. Increasing landscape connectivity (i.e. the degree to which the landscape facilitates movement between habitat patches) has been proposed as a key landscape-level strategy to counterbalance the negative effects of habitat fragmentation. A robust theoretical and methodological framework has been developed for the concept of connectivity, and an increasing body of empirical evidence supports the relevance of connectivity for biodiversity. However, the framework was built ignoring species that represent the dominant proportion of biodiversity on earth: microorganisms. The extent to which the existing conceptual and methodological frameworks on connectivity can be applied to microorganisms remain unknown. We reviewed existing evidence and analyzed methods to test the influence of connectivity on microorganisms. We included all types of microorganisms, from symbiotic to pathogenic and free-living microorganisms, across all ecosystems. We describe the effect of connectivity on microorganism populations and communities, and identify the limitations and large gaps in current knowledge. Microorganisms can differ from macroorganisms in their response to connectivity due to short (distance less than a meter) dispersal distance of some groups, longer time lag of microorganisms response (possibly accompanied by evolutionary processes) and host association. The latter relies on tight interactions and feedback effects that drive microbial-landscape relationships and lead to possible coadaptation processes. Incorporating the connectivity concept in microbial community assembly rules to preserve the diversity of microbial communities and the ecosystem services they provide could be a crucial step forward in the face of pressing global changes.

International audience; Photosynthesis in diatoms is performed using the same basic modules as cyanobacteria and plants. It can be regulated on multiple levels depending on the environmental cues, allowing diatoms to adjust their photosynthetic light reaction towards optimum whilst at the same time minimizing photodamage induced by light. In recent years, tremendous progress has been gained in understanding these acclimation processes, revealing several diatom-specific features. In this chapter, we trace several paths through the photosynthetic electron transport chain to optimize photosynthesis. We review how diatoms repair photoinactivated reaction centers and which mechanisms they have to preempt photodamage. Finally, photoprotection is set in an ecophysiological context, highlighting differences in photoprotection of diatoms from different habitats.

Tunas are among the most consumed seafood products but contain relatively high levels of methylmercury (MeHg), the most toxic form of mercury (Hg). Limited observations suggest tuna Hg levels vary in space and time, yet the drivers are not well understood. This thesis aimed to explore the origin and fate of MeHg in tunas at the global scale. We built the largest Hg database in tropical tunas (bigeye, yellowfin, and skipjack, n > 5,700), alongside tuna biological and ecological data, marine physical and biogeochemical variables, and atmospheric Hg estimates. Increasing tuna Hg concentrations were found in the late 1990s in the northwestern Pacific, concomitant with increasing anthropogenic Hg emissions from Asia. Elsewhere, we revealed stable long-term tuna Hg levels, which contrasts with an overall decline in Hg emissions and deposition, and suggests an inertia of the surface ocean resulting from legacy Hg accumulated in subsurface ocean over centuries. Moreover, global maps of tuna Hg levels highlighted strong spatial patterns among tunas, once accounting for MeHg bioaccumulation with tuna age/length. Our multidisciplinary approach showed the combined importance of marine biogeochemistry governing MeHg profiles in seawater, and tuna foraging depth, to explain these spatial patterns. Our spatial studies also confirmed a local anthropogenic Hg release effect enhancing tuna Hg levels along the Asia coasts. Complementary to observations of atmospheric Hg deposition and seawater MeHg levels, this thesis elevates tunas as releveant bio-monitoring tools to document changes of the marine Hg cycle in a context of reduction emission measures and climate change.; Le thon est l’un des poissons marins les plus consommés au monde malgré ses concentrations relativement élevées en méthylmercure (MeHg), la forme toxique du mercure (Hg). De fortes variations de ces concentrations entre espèces et régions sont observées mais encore peu comprises. Pour étudier l’origine et le devenir du MeHg dans les thons à l’échelle globale, nous avons constitué la plus grande base de données de concentrations de Hg dans les thons tropicaux (thon obèse, albacore et bonite à ventre rayé, n > 5700), intégrant des données biologiques et écologiques des thons, des variables physiques et biogéochimiques de l’océan, et des estimations de Hg atmosphérique. Une hausse des niveaux de Hg dans les thons a été constatée à la fin des années 1990 dans le Pacifique Nord-Ouest, en lien avec l’augmentation des émissions anthropiques de Hg depuis l’Asie. Ailleurs, les concentrations de Hg dans les thons sont restés stables au cours du temps, suggérant une inertie de l’océan de surface due au Hg anthropique accumulé au cours des siècles dans l’océan de subsurface. La cartographie des concentrations de Hg dans les thons a montré de fortes variations spatiales, dues à la variabilité de profondeur de plongée des thons et des niveaux de MeHg dissous dans l’eau, induites par des processus biogéochimiques. Nos études spatiales ont enfin confirmé un effet local des émissions anthropiques de Hg augmentant les concentrations de Hg dans les thons au large de l’Asie. Cette thèse démontre que les thons sont des outils de bio-surveillance pertinents pour documenter les changements du cycle marin du Hg, dans un contexte de réduction des émissions anthropiques et de changement climatique.

International audience; Pseudomonads play crucial roles in plant growth promotion and control of plant diseases. However, under natural conditions, other microorganisms competing for the same nutrient resources in the rhizosphere may exert negative control over their phytobeneficial characteristics. We assessed the expression of phytobeneficial genes involved in biocontrol, biostimulation and iron regulation such as, phlD, hcnA, acdS, and iron-small regulatory RNAs prrF1 and prrF2 in Pseudomonas brassicacearum co-cultivated with three phytopathogenic fungi, and two rhizobacteria in the presence or absence of Brassica napus, and in relation to iron availability. We found that the antifungal activity of P. brassicacearum depends mostly on the production of DAPG and not on HCN whose production is suppressed by fungi. We have also shown that the twocompeting bacterial strains modulate the plant growth promotion activity of P. brassicacearum by modifying the expression of phlD, hcnA and acdS according to iron availability. Overall, it allows us to better understand the complexity of the multiple molecular dialogues that take place underground between microorganisms and between plants and its rhizosphere microbiota and to show that synergy in favour of phytobeneficial gene expression may exist between different bacterial species.

International audience; It is widely recognized that major transportation infrastructures such as highways degrade habitats, increase the risk of collision mortality, and cause alterations in landscape connectivity by reducing connections between habitats due to the barrier effect. Wildlife crossings (underpasses and overpasses) have therefore become standard practice to reduce these effects on wildlife. Most studies aim to identify relevant locations for the creation of new wildlife crossings, but it is very rare for results based on modeling tools or animal movement records, for example, to be confronted with expert opinion and knowledge. Our paper provides a methodological framework combining modeling tools and field expertise from a multi-scale perspective. We used complementary connectivity metrics from graph theory to accurately quantify and spatialize the most relevant areas to improve habitat connectivity with multispecies conservation goals. The connectivity analysis was coupled with field expertise to take into account the local context, and technical and land feasibility. We prioritized existing road structures for improvement, found the best locations for new wildlife crossings, and made specific, costed technical recommendations. We empirically tested this approach on a large highway network in Northern France. This allowed us to define work principles to improve 109 existing road structures and to create underpasses or overpasses on 15 road sections. This innovative study for operational purposes has been a useful tool to assist the decision-making process of land-use planners who wish to improve wildlife crossings on major transportation infrastructures.

International audience; Tropical rivers are strongly influenced by stormwaters, pollutants and agro-pastoral activities. These systems are no longer able to maintain their native biota. Therefore, it seems important to understand how biological assemblages are driven by environmental gradients at different spatial scales. However, information on the relationships between the distribution of aquatic macroinvertebrates and environmental variables remains scarce in Cameroon. To improve our knowledge on the drivers of such distributions, a study was carried out at 11 contrasted sites from three catchments located in West Cameroon. This study aimed at understanding the spatio-temporal variations of 19 taxonomic metrics calculated for the benthic macroinvertebrate assemblages of these sites sampled during 13 months, concurrently with physico-chemical analyses of water quality. Two hundred and twelve taxa were caught. Diptera(rf-S), Shannon-Wiener diversity, 1–GOLD, total richness, Pielou evenness and Heteroptera(rf-S) revealed their high ability to respond to anthropogenic pressures or disturbances. Conductivity, water temperature, dissolved oxygen, nitrates, total hardness and alkalinity were identified as the main physico-chemical drivers of the taxonomic structure of benthic assemblages. These results will allow further exploration of the implementation of a tool for monitoring the ecological quality of West Cameroon rivers.

France is the first pesticide-consuming country in Europe. Glyphosate is the most used pesticide worldwide and glyphosate is detected in the general population of industrialized countries, with higher levels found in farmers and children. Little data was available concerning exposure in France. Our objective was to determine glyphosate levels in the French general population and to search for an association with seasons, biological features, lifestyle status, dietary habits, and occupational exposure. This study includes 6848 participants recruited between 2018 and 2020. Associated data include age, gender, location, employment status, and dietary information. Glyphosate was quantified by a single laboratory in first-void urine samples using ELISA. Our results support a general contamination of the French population, with glyphosate quantifiable in 99.8% of urine samples with a mean of 1.19 ng/ml + / − 0.84 after adjustment to body mass index (BMI). We confirm higher glyphosate levels in men and children. Our results support glyphosate contamination through food and water intake, as lower glyphosate levels are associated with dominant organic food intake and filtered water. Higher occupational exposure is confirmed in farmers and farmers working in wine-growing environment. Thus, our present results show a general contamination of the French population with glyphosate, and further contribute to the description of a widespread contamination in industrialized countries.

International audience; Objectives: In the management of diabetic patients on insulin therapy, adherence to medication is a key element for avoiding chronic complications. The purpose of this study was to evaluate diabetic patients' ability to translate glycemic results into an appropriate insulin dose and thus, adherence to insulins.Methods: This was an observational, retrospective, monocentric pilot study. Diabetic patients on insulin therapy being followed at the metabolic and endocrine diseases department were divided into two groups depending on their mode of glycemic control at home: capillary glycemia (Notebook group) or interstitial glycemia using the FreeStyle Libre® flash system (FSL group). Adherence was assessed based on the rate of compliance in adapting insulin doses to the prescribed protocols (depending on type of insulin, glycemic targets, and patients' characteristics) by a pharmacy resident and a senior diabetologist. Good adherence was defined as a minimum rate of 80% of conforming insulin injections for each patient.Results: A total of 50 patients were included, 35 in the Notebook group and 15 in the FSL group. Two-thirds of patients were non-adherent to insulin. Dose adjustment errors mainly concerned rapid-acting insulin with 51.1% of non- conformities, 10.0% of which were due to underdosing in the Notebook group and 21.7% to overdosing in the FSL group. Hyperglycemia was predominant in both populations with a median time in range of 19.0% in the FSL group and well below recommendations (>70%).Conclusions: Despite the use of increasingly efficient, easy-to-use devices in diabetes monitoring, insulin non-adherence and glycemic imbalance are unresolved major issues. Diabetic patients require reinforced medical follow-up for optimal insulin management.

Genetic diversity at population scale, depends on species life-history traits, population dynamics and local and global environmental factors. We first investigate the effect of life-history traits on the neutral genetic diversity of a single population using a deterministic mathematical model. When the population is stable, we show that semelparous species with precocious maturation and iteroparous species with delayed maturation exhibit higher diversity because their life history traits tend to balance the lifetimes of non reproductive individuals (juveniles) and adults which reproduce. Then, we extend our model to a metapopulation to investigate the additional effect of dispersal on diversity. We show that dispersal may truly modify the local effect of life history on diversity. As a result, the diversity at the global scale of the metapopulation differ from the local diversity which is only described through local life history traits of the populations. In particular, dispersal usually promotes diversity at the global metapopulation scale.

Phytoremediation is an ecological method based on the use of tolerant and (hyper)accumulator plants to rehabilitate sites polluted by heavy metals. For a better use of these plants, a deep understanding of the mechanisms that control metal tolerance and accumulation is needed. The Brassicaceae Hirschfeldia incana grows naturally in contaminated sites. Under these conditions, it exhibits significant biomass and a high capacity for lead tolerance and accumulation (1; 2). To optimize its use in Pb phytoremediation processes, we analyzed the variation of metabolomic profile by GC-MS in H.incana plants treated with Pb for 3 and 15 days. The metabolomic analysis of the organic fraction of H.incana’s aerial part showed an increase in the concentration of organic acids since the first days of treatment and a decrease in the concentration of membrane lipids and steroids, thus revealing signs of toxicity in form of lipid peroxidation. On the other hand, after 15 days of treatment, an increase in the total concentration of lipids and steroids was reported, indicating a sort of adaptation of H.incana to Pb stress. A comparison of enzyme activities and MDA content between Pb-treated and untreated plants showed a decrease in peroxidase activity and a slight increase in catalase activity after 15 days of treatment. MDA content decreased after 3 days of treatment and then increased after 15 days of treatment. Our results suggest that the plant compensates lipid peroxidation by activating other lipid biosynthetic pathways which explain the augmentation of lipid amount in 15 days treated plants., La phytoremédiation est une méthode écologique basée sur l’utilisation des plantes tolérantes et (hyper)accumulatrices pour la réhabilitation des sites miniers pollués par les métaux lourds. Pour une meilleure utilisation de ces plantes, une connaissance approfondie des mécanismes qui contrôlent la tolérance et l’accumulation des métaux demeure nécessaire. La Brassicacée Hirschfeldia incana pousse naturellement dans les sites contaminés. Dans ces conditions, elle présente une biomasse importante et une forte capacité de tolérance et d’accumulation du plomb (1, 2). Afin d’optimiser son utilisation dans des procédés de phytoremédiation du plomb, nous avons analysé les variations du profil métabolomique par GC-MS des plantes d’H.incana traitées par le Pb pendant 3 et 15 jours. L’analyse métabolomique de la fraction organique de la partie aérienne d’H.incana a montré une augmentation de la concentration des acides organiques dès le début du traitement et une diminution de la concentration des lipides membranaires et des stéroïdes révélant ainsi des signes de toxicité. En revanche, la concentration des lipides et des stéroïdes a augmenté après 15 jours du traitement. Une comparaison des activités enzymatiques et de la teneur en MDA entre des plantes traitées et non traitées a montré une diminution de l’activité de peroxydase et une augmentation de l’activité de catalase après 15 jours du traitement. La teneur en MDA a diminué chez les plantes traitées pendant 3 jours et a augmenté après 15 jours du traitement. Ces résultats suggèrent que probablement la plante compense la dégradation des lipides par activation d’autres voies de biosynthèses des lipides.

International audience; Among the many inhabitants of planktonic communities, several lineages have biomineralized intricate skeletons. These have existed for millions of years and include the Radiolaria, a group of marine protists, many of which bear delicate mineral skeletons of different natures. Radiolaria are well known for their paleontological signatures, but little is known about the ecology of modern assemblages. They are found from polar to tropical regions, in the sunlit layers of the ocean down to the deep and cold bathypelagic. They are closely involved in the biogeochemical cycles of silica, carbon and strontium sulfate, carrying important amounts of such elements to the deep ocean. However, relatively little is known on the actual extent of genetic diversity or biogeographic patterns. The rapid emergence and acceptance of molecular approaches have nevertheless led to major advances in our understanding of diversity within and evolutionary relationships between major radiolarian groups. Here, we review the state of knowledge relating to the classification, diversity and ecology of extant radiolarian orders, highlighting the substantial gaps in our understanding of the extent of their contribution to marine biodiversity and their role in marine food webs.

La probabilité est forte pour que les chênaies de la région Centre Val de Loire soient dans les prochaines décades le sujet, à la fois, de dépérissements marqués et d’un manque de régénération permettant le renouvellement des peuplements. Sur le dispositif OPTMix (Oak Pine Tree Mixture, https://optmix.inrae.fr/), environ un tiers des chênes (Q. petraea) sont dépérissants, à des degrés divers en 2021. La première variable affectée par ces dépérissements est la croissance, notamment en épaisseur. La deuxième variable est la surface foliaire, réduite d’environ un tiers. Ces réductions résultent notamment des fortes contraintes hydrique et thermique subies durant les années 2018 à 2020. La durée de la contrainte hydrique (nombre de jours sur la période de croissance), plus que son intensité, est un facteur déterminant des dépérissements observés. Par ailleurs, la proportion de chênes dépérissants est plus élevée dans les peuplements les moins denses. Cet effet résulte sans doute des plus fortes contraintes hydrique et thermique subies par la couronne des arbres dans ces peuplements ouverts, le microclimat y étant moins tamponné. Les arbres dépérissants en 2021 ont tous eu une croissance réduite dans le passé, et ce quelle que soit l’année considérée (depuis 2014). Cette propriété pourrait être exploitée pour réaliser des éclaircies sans sacrifice sur la base de la croissance passée des chênes. En absence de régulation de la pression d’herbivorie et de la gestion de la végétation interférente, la régénération naturelle de chêne sessile sur les placettes OPTMix ne permettra pas de constituer un stock suffisant pour renouveler ces peuplements dépérissants. Cela réduit considérablement les capacités d’adaptation génétique de ces peuplements aux contraintes du climat.

International audience; Biological nitrification inhibition (BNI) has already led to several studies mainly focused on underlying molecular mechanisms and applications to agriculture. We argue that it is also important to study BNI more systematically from the ecological and evolutionary points of view to understand its implications for plants and soil nitrifiers as well as its consequences for ecosystems. Therefore, we propose here a dedicated research agenda identifying the most critical research questions: (1) How is BNI distributed across plant phylogeny and why has it been selected? (2) What are the costs-to-benefits balance of producing BNI compounds and the relative impacts on BNI evolution? (3) Can we understand the evolutionary pressures leading to BNI and identify the environmental conditions favorable to BNI plants? (4) How has BNI coevolved with plant preference for ammonium vs. nitrate? (5) Diverse BNI compounds and various inhibition mechanisms have been described, but implications of this diversity are not understood. Does it allow inhibition of various groups of nitrifiers? (6) Does this diversity of BNI compounds increase the efficiency, spatial extension, and duration of BNI effect? (7) What are the impacts of BNI compounds on other soil functions? (8) Can field experiments, coupled to scanning of the diversity of BNI capabilities within plant communities, evaluate whether BNI influences plant-plant competition and plant coexistence? (9) Can field quantification of various nitrogen (N) fluxes assess whether BNI lead to more efficient N cycling with lower losses and hence increased primary production? (10) Can the impact of BNI on N budgets and climate (through its impact on N2O emissions and its indirect impact on carbon budget) be evaluated at the regional scale? We discuss why implementing this research program is crucial both for the sake of knowledge and to develop applications of BNI for agriculture.

International audience; How waste will be managed in the future? Will humans be able to design zero-waste products and systems, or will therebe a continuous urban mining to recycle waste in the circular economy? Here, new insights have been recently provided by the COVID-19 pandemic, which has somehow accelerated society evolution and thus provided a glimpse at what might happen in the future. In particular, lockdowns have suddenly amplified working from home with computers, increased the amount plastic and paper packages and decreased waste transportations. Here, we discuss issues of electronic waste (E-waste) pollution, toxicity and urban mining.

B.J.-A. was funded by the Marie Curie Clarín-COFUND program of the Principality of Asturias-EU (ACB17-26) and the Spanish Research Agency (AEI/10.13039/501100011033)., Testolin, R., Attorre, F., Borchardt, P., Brand, R.F., Bruelheide, H., Chytrý, M., De Sanctis, M., Dolezal, J., Finckh, M., Haider, S., Hemp, A., Jandt, U., Kessler, M., Korolyuk, A.Y., Lenoir, J., Makunina, N., Malanson, G.P., Montesinos-Tubée, D.B., Noroozi, J., Nowak, A., Peet, R.K., Peyre, G., Sabatini, F.M., Šibík, J., Sklenář, P., Sylvester, S.P., Vassilev, K., Virtanen, R., Willner, W., Wiser, S.K., Zibzeev, E.G., Jiménez-Alfaro, B.

Organisms can gain information about predation risks from their parents, their own personal experience, and their conspecifics and adjust their behavior to alleviate these risks. These different sources of information can, however, provide conflicting information due to spatial and temporal variation of the environment. This raises the question of how these cues are integrated to produce adaptive antipredator behavior. We investigated how common lizards (Zootoca vivipara) adjust the use of conspecific cues about predation risk depending on whether the information is maternally or personally acquired. We experimentally manipulated the presence of predator scent in gestating mothers and their offspring in a full-crossed design. We then tested the consequences for social information use by monitoring offspring social response to conspecifics previously exposed to predator cues or not. Lizards were more attracted to the scent of conspecifics having experienced predation cues when they had themselves no personal information about predation risk. In contrast, they were more repulsed by conspecific scent when they had personally obtained information about predation risk. However, the addition of maternal information about predation risk canceled out this interactive effect between personal and social information: lizards were slightly more attracted to conspecific scent when these two sources of information about predation risk were in agreement. A chemical analysis of lizard scent revealed that exposure to predator cues modified the chemical composition of lizard scents, a change that might underlie lizards’ use of social information. Our results highlight the importance of considering multiple sources of information while studying antipredator defenses., L.W. was supported by the Fyssen Foundation Post-Doctoral Fellowship and J.C. by an ANR-12-JSV7-0004-01. This work was supported by an “Investissements d’avenir” programme from the Agence Nationale de la Recherche number ANR-11- INBS-0001 Ana EE-Services.

International audience; Cats Felis catus, in all their forms (domestic, free-roaming/stray and feral), have been identified as a major global threat to biodiversity, especially birds and small mammals. However, there has been little previous consideration of the extent and impact of predation of bats by cats, or of whether specific characteristics make certain species of bats particularly vulnerable to predation by cats. We reviewed the impact of cats on bats, based on a collation of scientific literature and the International Union for Conservation of Nature (IUCN) Red List database. Our aim was to produce a synthesis of the extent to which cats prey upon and threaten bats. We also collated available data on cat diet, which provide information on predation rates of bats by cats. Few studies (n = 44) have identified bat species preyed upon or threatened by cats, with a disproportionate number of studies from islands. In these studies, 86 bat species (about 7% of the global extant tally) are reported as preyed upon or threatened by cats, and about one quarter of these species are listed as Near Threatened or threatened (IUCN categories Critically Endangered, Endangered, or Vulnerable). In IUCN Red List assessments, cats are more frequently mentioned as a threat to threatened or Near Threatened bat species than to non-threatened species (IUCN category Least Concern). In studies reporting on the incidence of bats in cat dietary samples (scats, stomachs and guts), the frequency of occurrence of bats in samples averaged 0.7 ± 2.1% (mean ± standard deviation; n = 102). Many studies had sample sizes that were too small to be likely to detect bats. All forms of cat are reported to kill bats, and such predation has been reported in all major terrestrial habitats. We conclude that predation by cats is an under-appreciated threat to the world’s bat species.

International audience; Invasive alien aquatic plant species (IAAPs) cause serious ecological and economic impact and are a major driver of changes in aquatic plant communities. Their invasive success is influenced by both abiotic and biotic factors. Here, we summarize the existing knowledge on the biology of 21 IAAPs (four free-floating species, eight sediment-rooted, emerged or floating-leaved species, and nine sediment-rooted, submerged species) to highlight traits that are linked to their invasive success. We focus on those traits which were documented as closely linked to plant invasions, including dispersal and growth patterns, allelopathy and herbivore defence. The traits are generally specific to the different growth forms of IAAPs. In general, the species show effective dispersal and spread mechanisms, even though sexual and vegetative spread differs strongly between species. Moreover, IAAPs show varying strategies to cope with the environment. The presented overview of traits of IAAPs will help to identify potential invasive alien aquatic plants. Further, the information provided is of interest for developing species-specific management strategies and effective prevention measures.

International audience; Passive Acoustic Monitoring offers promising opportunities for biodiversity assessments and species conservation and is still in development. The robustness of community metrics depends on sampling effort and acoustic surveys should be adjusted for cost-effectiveness. Using a large-scale acoustic survey of bat assemblages conducted along 5487 survey nights across France, we assessed the effect of sampling duration on the level of confidence of four community metrics (total bat activity, species of conservation concern activity, species richness, and community specialisation index). We further investigated whether this effect varied across habitats and seasons. Overall, a high level of confidence (i.e., 95% similarity between cumulated survey nights) was reached after 2 to >20 sampling nights, depending on the community metric, the habitat and the season considered. CSI required the lowest sampling duration. A higher sampling duration was required in three-dimensionally structured habitats (e.g., forests) and habitats unfavourable to bats (e.g., intensive farmlands), while a high degree of confidence was reached earlier in more favourable habitats and non-intensive farmlands, and during the season of higher activity. Beyond providing recommendations for the design of context-dependent minimum sampling duration in acoustic surveys, we show that weighted community indices such as the CSI are efficient summary measures, and advocate for their use when monitoring resources are limited.

[Aims] (a) To determine the contribution of current macro-environmental factors in explaining the phylogenetic structure of European forest vegetation, (b) to map and describe spatial patterns in their phylogenetic structure and (c) to examine which lineages are the most important contributors to phylogenetic clustering and whether their contribution varies across forest types and regions. [Location] Europe. [Taxon] Angiosperms. [Methods] We analysed the phylogenetic structure of 61,816 georeferenced forest vegetation plots across Europe considering alternative metrics either sensitive to basal (ancient evolutionary dynamics) or terminal (recent dynamics) branching in the phylogeny. We used boosted regression trees to model metrics of the phylogenetic structure as a function of current macro-environmental factors. We also identified clades encompassing significantly more taxa than under random expectation in phylogenetically clustered plots. [Results] Phylogenetic clustering was driven by climatic stress and instability and was strong in the areas glaciated during the Pleistocene, likely reflecting limited postglacial migration, and to a lower extent in areas of northern-central Europe and in summer-dry Mediterranean regions. Phylogenetic overdispersion was frequent in the hemiboreal zone in Russia, in some areas around the Mediterranean Basin, and along the Atlantic seaboard of the Iberian Peninsula. The families Ericaceae, Poaceae and Fagaceae were overrepresented in clustered plots in different regions of Europe. [Main conclusions] We provide the first maps and analyses on the phylogenetic structure of European forest vegetation at the plot level. Our results highlight the role of environmental filtering, postglacial dispersal limitation and spatial transitions between major biomes in determining the distribution of plant lineages in Europe., The study was supported by the Czech Science Foundation (19-28491X). IB and JAC were funded by the Basque Government (IT936-16). JCS considers this work a contribution to his VILLUM Investigator project “Biodiversity Dynamics in a Changing World” funded by VILLUM FONDEN (grant 16549).

Transfer efficiency is the proportion of energy passed between nodes in food webs. It is an emergent, unitless property that is difficult to measure, and responds dynamically to environmental and ecosystem changes. Because the consequences of changes in transfer efficiency compound through ecosystems, slight variations can have large effects on food availability for top predators. Here, we review the processes controlling transfer efficiency, approaches to estimate it, and known variations across ocean biomes. Both process-level analysis and observed macroscale variations suggest that ecosystem-scale transfer efficiency is highly variable, impacted by fishing, and will decline with climate change. It is important that we more fully resolve the processes controlling transfer efficiency in models to effectively anticipate changes in marine ecosystems and fisheries resources.

International audience; Landsat-TM of 2001 covering Iceland (15.5°W-21°W, 64.5°N-67°N) was processed using SAGA GIS for testing distance-based Vegetation Indices (VIs): four approaches of Perpendicular Vegetation Index (PVI) and two approaches of Transformed Soil Adjusted Vegetation Index TSAVI. The PVI of vegetation from the soil background line indicated healthiness as a leaf area index (LAI). The results showed that the reflectance for vegetation has a linear relation with soil background line. Four PVI models and two TSAVI shown coefficients of determination with LAI. The dataset demonstrate variations in the calculated coefficients. The mode in the histograms of the PVI based on four different algorithms show the difference:-7.1,-8.36, 2.78 and 7.0. The dataset for the two approaches of TSAVI: first case ranges in 4.4.-80.6 with a bellshape mode of a histogram (8.09 to 23.29) for the first algorithm and an irregular shape for the second algorithm with several modes starting from 0.11 to 0.2 and decreasing to 0.26. SAGA GIS permits the calculation of PVI and TSAVI by computed NDVI based on the intersection of vegetation and soil background. Masking the NIR and R, a linear regression of grids was performed using an equation embedded in SAGA GIS. The advantages of the distance-based PVI and TSAVI consists in the adjusted position of pixels on the soil brightness line which refines it comparing to the slope-based VIs. The paper demonstrates SAGA GIS application in agricultural studies.

International audience; Questions. What are the functional trade-offs of vascular plant species in global alpine ecosystems? How is functional variation related to vegetation zones, climatic groups and biogeographic realms? What is the relative contribution of macroclimate and evolutionary history in shaping the functional variation of alpine plant communities? Location. Global. Methods. We compiled a data set of alpine vegetation with 5,532 geo-referenced plots, 1,933 species and six plant functional traits. We used principal component analysis to quantify functional trade-offs among species and trait probability density to assess the functional dissimilarity of alpine vegetation in different vegetation zones, climatic groups and biogeographic realms. We used multiple regression on distance matrices to model community functional dissimilarity against environmental and phylogenetic dissimilarity, controlling for geographic distance. Results. The first two PCA axes explained 66% of the species’ functional variation and were related to the leaf and stem economic spectra, respectively. Trait probability density was largely independent of vegetation zone and macroclimate but differed across biogeographic realms. The same pattern emerged for both species pool and community levels. The effects of environmental and phylogenetic dissimilarities on community functional dissimilarity had similar magnitude, while the effect of geographic distance was negligible. Conclusions. Plant species in alpine areas reflect the global variation of plant function, but with a predominant role of resource use strategies. Current macroclimate exerts a limited effect on alpine vegetation, mostly acting at the community level in combination with evolutionary history. Global alpine vegetation is functionally unrelated to the vegetation zones in which it is embedded, exhibiting strong functional convergence across regions

The authors, under the aegis of the Veterinary Academy of France, studied how the scientific literature questions the relationship between the emergence of zoonosis or new human and animal infectious diseases and the loss of biodiversity observed under anthropogenic changes. This review describes how some pathogens can spill over from «wild reservoir » to domestic animal populations and human. The exploitation and destruction of natural environments such as primary forests and tropical wetlands, and closest proximity amongst species that is consecutive promote contacts that allow pathogens to circulate from the wild natural reservoirs to humans, who then spread these agents all over the world. However, there is a large array of modalities with regard to the transmission and further spread of pathogens from biodiversity. It is premature to draw general conclusions on these relationships from this review only. However, the study emphasizes the needs to strengthen a multidisciplinary approach in research as well as in practice and teaching. Such multi-disciplinary approach should involve close collaborations between veterinary and human medicines, ecology, other biological and environmental disciplines and the human sciences., Les auteurs réunis sous l’égide de l’Académie Vétérinaire de France ont étudié comment la littérature scientifique interroge le rapport entre l’émergence de zoonoses ou de nouvelles maladies infectieuses humaines et animales, d’une part et les pertes de biodiversité observées sous l’effet des pressions humaines d’autre part. L’examen de la littérature consultée décrit comment certains agents pathogènes peuvent passer du «réservoir » naturel sauvage à celui des animaux domestiques et aux populations humaines. L’exploitation et la destruction des milieux naturels comme les forêts primaires et les zones humides tropicales, ainsi que le rapprochement d’espèces consécutif, favorisent des contacts permettant le passage (direct ou via des réservoirs intermédiaires) d’agents pathogènes du réservoir sauvage aux humains, qui propagent ensuite ces agents sur la planète. Il existe toutefois une importante variabilité des modalités permettant le passage, puis la propagation locale et planétaire des agents pathogènes issus de la biodiversité. Il est prématuré de tirer des conclusions générales sur les relations que cette revue scientifique a examinées. L’article suggère néanmoins que l’approche pluridisciplinaire doit progresser tant dans le domaine de la recherche que dans celui des pratiques et de l’enseignement. Cette pluridisciplinarité implique une étroite collaboration entre les médecines vétérinaires et humaines, l’écologie de la santé, d’autres disciplines biologiques et environnementales, et les sciences humaines., Robardet Emmanuelle, Charbonnel Nathalie, Guégan Jean-françois, Monchâtre-Leroy Élodie, Parodi André, Gauchot Jean-Yves, Zeller Hervé, Boussarie Didier, Artois Marc. Maladies transmissibles et altération de la biodiversité : Quelles relations ?. In: Bulletin de l'Académie Vétérinaire de France tome 174, 2021. pp. 149-159.

Earthworms are important ecosystem engineers, and assessment of the risk of plant protection products toward them is part of the European environmental risk assessment (ERA). In the current ERA scheme, exposure and effects are represented simplistically and are not well integrated, resulting in uncertainty when the results are applied to ecosystems. Modeling offers a powerful tool to integrate the effects observed in lower tier laboratory studies with the environmental conditions under which exposure is expected in the field. This paper provides a summary of the (In)Field Organism Risk modEling by coupling Soil Exposure and Effect (FORESEE) Workshop held 28-30 January 2020 in Düsseldorf, Germany. This workshop focused on toxicokinetic-toxicodynamic (TKTD) and population modeling of earthworms in the context of ERA. The goal was to bring together scientists from different stakeholder groups to discuss the current state of soil invertebrate modeling and to explore how earthworm modeling could be applied to risk assessments, in particular how the different model outputs can be used in the tiered ERA approach. In support of these goals, the workshop aimed at addressing the requirements and concerns of the different stakeholder groups to support further model development. The modeling approach included 4 submodules to cover the most relevant processes for earthworm risk assessment: environment, behavior (feeding, vertical movement), TKTD, and population. Four workgroups examined different aspects of the model with relevance for risk assessment, earthworm ecology, uptake routes, and cross-species extrapolation and model testing. Here, we present the perspectives of each workgroup and highlight how the collaborative effort of participants from multidisciplinary backgrounds helped to establish common ground. In addition, we provide a list of recommendations for how earthworm TKTD modeling could address some of the uncertainties in current risk assessments for plant protection products. Integr Environ Assess Manag 2021;17:352-363. © 2020 SETAC.

International audience; Aim. The majority of work done to gather information on the Earth's biodiversity has been carried out using in-situ data, with known issues related to epistemology (e.g., species determination and taxonomy), spatial uncertainty, logistics (time and costs), among others. An alternative way to gather information about spatial ecosystem variability is the use of satellite remote sensing. It works as a powerful tool for attaining rapid and standardized information. Several metrics used to calculate remotely sensed diversity of ecosystems are based on Shannon’s information theory, namely on the differences in relative abundance of pixel reflectances in a certain area. Additional metrics like the Rao’s quadratic entropy allow the use of spectral distance beside abundance, but they are point descriptors of diversity, that is they can account only for a part of the whole diversity continuum. The aim of this paper is thus to generalize the Rao’s quadratic entropy by proposing its parameterization for the first time. Innovation. The parametric Rao’s quadratic entropy, coded in R, (a) allows the representation of the whole continuum of potential diversity indices in one formula, and (b) starting from the Rao’s quadratic entropy, allows the explicit use of distances among pixel reflectance values, together with relative abundances. Main conclusions. The proposed unifying measure is an integration between abundance- and distance-based algorithms to map the continuum of diversity given a satellite image at any spatial scale. Being part of the rasterdiv R package, the proposed method is expected to ensure high robustness and reproducibility.

Valvometry techniques used to monitor bivalve gaping activity have elucidated numerous relationships with environmental fluctuations, along with biological rhythms ranging from sub-daily to seasonal. Thus, a precise understanding of the natural activity of bivalves (i.e., not exposed to stressful environmental variations) is necessary as a baseline for detecting abnormal behaviors (deviations). This knowledge is also needed to reliably interpret observations of bivalve gaping behavior and associated biological processes (e.g., respiration, nutrition) acquired over time-limited periods. With this in mind, we investigated the natural daily gaping activity of the great scallop (Pecten maximus) by continuously monitoring 35 individuals in several individual tanks and in situ (Bay of Saint-Brieuc, Brittany, France) using fully autonomous Hall effect sensors. Our results revealed a circadian cycle (τ = 24.0h) in scallop gaping activity. Despite significant inter-individual variability in mean opening and cycle amplitude, almost all individuals (87.5%) exhibited nocturnal activity, with valves more open at night than during the day. A shift in light regime in the tanks triggered an instantaneous change in opening pattern, indicating that light levels strongly determine scallop activity. Based on the opening status of scallops, we also identified several gaping behaviors deviating from the regular daily pattern (lack of rhythmicity, high daytime opening), potentially reflecting physiological weakness. While further long-term studies are required to fully understand the natural activity of scallops, these findings pave the way for studies focused on the scallop response to external factors and introduce further research into the detection of abnormal behaviors. Coupling observations of diel valve gaping cycles with other daily variations in organismal and environmental parameters could help explain mechanisms driving the growth patterns of scallops observed in their shell striations. From a technical perspective, our field-based monitoring demonstrates the suitability of autonomous valvometry sensors for studying mobile subtidal bivalve activity in remote offshore environments.

International audience; Biodiversity offsets aim to compensate the negative residual impacts of development projects on biodiversity, including ecosystem functions, uses by people and cultural values. Conceptually, ecosystem services (ES) should be considered, but in practice this integration rarely occurs. Their consideration would improve the societal impact of biodiversity offsets. However, the prioritisation of ES in a given area is still limited. We developed a framework for this purpose, applied in rangelands landscapes in Kazakhstan, in the context of uranium mining. We assumed that different landscapes provide different ES, and that stakeholders perceive ES according to their category (e.g., elders and herders) and gender. We performed qualitative, semi-structured interviews with a range of stakeholders. Using the Common International Classification of Ecosystem Services, we identified 300 ES in 31 classes across 8 landscape units. We produced a systemic representation of the provision of ES across the landscapes. We showed a significant link between ES and landscape units, but not between ES and stakeholder categories or gender. Stakeholders mostly identified ES according to the location of their villages. Therefore, we suggest that the biodiversity offsets should target ES provided by the landscape unit where mining activities occur and would be most interesting in the landscapes common to all villages. By performing a systemic representation, potential impacts of some offset strategies can be predicted. The framework was therefore effective in determining a bundle of ES at a landscape scale, and in prioritising them for future biodiversity offset plans.

International audience; Benthic diatoms are unicellular microalgae that are routinely used as bioindicators for monitoring the ecological status of freshwater. Their identification using light microscopy is a time-consuming and laborintensive task that could be automated using deep-learning. However, training such networks relies on the availability of labeled datasets, which are difficult to obtain for these organisms. Herein, we propose a method to generate synthetic microscopy images for training. We gathered individual objects, i.e. 9230 diatoms from publicly available taxonomic guides and 600 items of debris from available real images. We collated a comprehensive dataset of synthetic microscopy images including both diatoms and debris using seamless blending and a combination of parameters such as image scaling, rotation, overlap and diatom-debris ratio. We then performed sensitivity analysis of the impact of the synthetic data parameters for training state-of-the art networks for horizontal and rotated bounding box detection (YOLOv5). We first trained the networks using the synthetic dataset and fine-tuned it to several real image datasets. Using this approach, the performance of the detection network was improved by up to 25% for precision and 23% for recall at an Intersectionover-Union(IoU) threshold of 0.5. This method will be extended in the future for training segmentation and classification networks.

International audience

International audience; Climate change is related to an increase in frequency and intensity of extreme events such as heatwaves. It is well established that such events may worsen the current world-wide biodiversity decline. In many organisms, heat stress is associated with direct physiological perturbations and could lead to a decrease of fitness. In contrast to endotherms, heat stress resistance has been poorly investigated in heterotherms; especially in insects, in which the internal physiological mechanisms available to regulate body temperature are almost negligible making them sensitive to extreme temperature variations.Wild bees are crucial pollinators for wild plants and crops. Among them, bumblebees are experiencing a strong decline across the world. Therefore, the ongoing global decline of these insect pollinators partly due to climate change could cause major economic issues.Here we assess how simulated heatwaves impact fertility and attractiveness (key parameters of sustainability) of bumblebee males. We used three model species: Bombus terrestris, a widespread and warm-adapted species, B. magnus and B. jonellus, two declining and cold-adapted species.We highlight that heat shock (40 degrees C) negatively affects sperm viability and sperm DNA integrity only in the two cold-adapted species. Heat shock can also impact the structure of cephalic labial glands and the production of pheromones only in the declining species.The specific disruption in key reproductive traits we identify following simulated heatwave conditions could provide one important mechanistic explanation for why some pollinators are in decline through climate change.A free Plain Language Summary can be found within the Supporting Information of this article.

Vegetation of Cameroon includes a variety of landscape types with high biodiversity. Ecological monitoring of Yaoundé requires visualization of vegetation types in context of climate change. Vegetation Indices (VIs) derived from Sentinel-2 multispectral satellite image were analyzed in SAGA GIS to separate wetland biomes, as well as savannah and tropical rainforests. The methodology includes computing 6 VIs: NDVI, DVI, SAVI, RVI, TTVI, CTVI. The VIs shown correlation of data with vegetation distribution rising from wetlands, grassland, savanna, and shrub land towards tropical rainforests, increasing values along with canopy greenness, while also being inversely proportional to soils, urban spaces and Sanaga River. The study contributed to the environmental studies of Cameroon and demonstration of the satellite image processing.

To understand how and to what extent single or multiple perturbations can alter the relationships between the abundances of different nitrifier groups and nitrification, soil microcosms were exposed to six disturbance treatments: a heat shock, cold shock, or control conditions applied to undisturbed soils or to soils that had previously been subjected to a first heat shock. We monitored the recovery of the abundances of four main nitrifier groups (ammonia-oxidizing archaea and bacteria, AOA and AOB, respectively, and Nitrobacter and Nitrospira nitrite oxidizers) as well as nitrification activity for 25 days. AOA were sensitive to cold shocks, whereas AOB were not; the latter were sensitive to heat shock. Despite the variations, both groups were resilient to the first disturbance. In contrast, Nitrobacter was affected by both disturbances, whereas Nitrospira was resistant to both shocks. Prior exposure to a heat shock affected each group’s responses as well as the relationships between them. For example, AOB were more vulnerable to heat shock in pre-exposed soils, whereas under the same circumstances, AOA were resilient. Nitrification activity was resistant to the first disturbances, but a legacy effect was observed, and nitrification was highest in Heat-Heat and lowest in Heat-Cold treatments. Overall, our study shows that within soil nitrifiers, temporal patterns and legacy effects interact to result in complex disturbance responses.

International audience; Understanding the ecological and behavioral variation of primates is central to improving conservation strategies. Studies of chimpanzees (Pan troglodytes) have shown marked behavioral variability across a wide range of habitats. By comparison, bonobos (Pan paniscus) occur mainly in continuous forest sites, and socioecological models explaining behavioral differences between the two species are based on the assumption that bonobo habitat is richer and more stable than chimpanzee habitats. The objective of this study was to assess bonobo ecology in a forest-savanna mosaic. We specifically explored 1) bonobo home range size, habitat use, and dietary composition; 2) forest fragmentation in a bonobo community's home range; and 3) seasonality of dietary diversity, habitat use, and spatial distribution. Using 2 years of observational data on location, habitat type, and dietary composition, we found that the bonobo community's home range size, density, and dietary diversity were similar to those observed in continuous forest sites. Bonobos used areas with lower forest fragmentation than the surrounding areas and preferentially spent time in forested habitats. During the dry season, bonobos consumed a lower diversity of fruit species, spent more time in sparse forest with Marantaceae understory, and were closer to the seasonal center of their home range than during the rainy season. Our results contribute to our understanding of behavioral variation in bonobos and suggest that forest-savanna mosaic is valuable to bonobo conservation.

International audience; The ecology of the young stages of allis shad Alosa alosa is poorly documented, although they can be exposed to many pressures during their freshwater phase and their downstream migration. When passing through systems such as the Gironde-Garonne-Dordogne watershed (GGD, SW France), they can be subjected to high temperatures and low levels of oxygen (hypoxia). The aim of this work is to assess the tolerance of young Alosa alosa at four ages (c. 10, 30, 60 and 85 days old) by challenging them to different temperatures (18, 22, 26 and 28C) together with decreasing oxygen saturation levels (from 100% to 30%). Survival of the 10-day-old individuals was not influenced by oxy-thermic conditions, but high stress levels were detected and perhaps this age class was too fragile regarding the constraint of the experimental design. Survival at 30 and at 60 days old was negatively influenced by the highest temperatures tested alone (from 26C and from 28C, respectively) but no effect was detected at 85 days old up to 28C. A combined effect of temperature and oxygen level was highlighted, with heat accelerating survival decrease when associated with oxygen level depletion: essentially, survival was critical (

International audience; Ant communities are extremely diverse and provide a wide variety of ecological functions in tropical forests. Here we investigated the abiotic factors driving ant composition turnover across an elevational gradient at Mont Itoupé, French Guiana. Mont Itoupé is an isolated mountain whose top is covered by cloud forests, a biogeographical rarity that is likely to be threatened according to climate change scenarios in the region. We examined the influence of six soil, climatic and LiDAR derived vegetation structure variables on leaf-litter ant assembly (267 species) across nine 0.12-ha plots disposed at three elevations (ca. 400, 600 and 800m asl). We tested (a) whether species cooccurring within a same plot or a same elevation were more similar in terms of taxonomic, functional and phylogenetic composition, than species from different plots/elevations, and (b) which environmental variables significantly explained compositional turnover among plots. We found that the distribution of species and traits of ant communities along the elevational gradient was significantly explained by a turnover of environmental conditions, particularly in soil phosphorus and sand content, canopy height and mean annual relative humidity of soil. Our results shed light on the role exerted by environmental filtering in shaping ant community assembly in tropical forests. Identifying the environmental determinants of ant species distribution along tropical elevational gradients could help predicting the future impacts of global warming on biodiversity organization in vulnerable environments such as cloud forests.

International audience; Un article de vulgarisation publié dans The Conversation.

Of the many behaviors that an animal exhibits, movement is one of the main studied components of organisms. Investigating the intricacies of movement can contribute to our understanding of the mechanisms connecting spatial behavior to population demography. Animals must move in the landscape to select habitats containing the necessary resources for their survival and to maximize their reproductive success. Choosing the right habitat however is not a simple task since individuals must account for predators, conspecifics, and landscape configuration to decide on how and where to move. Additionally, the movement of animals in their environment may depend on their morphological, physiological, and ecological traits. Until now, most studies related home range size and movement to environmental variables, with few relating these two spatial components to the internal state of the animal. During my thesis, I tried to resolve this issue by evaluating how the intertwined relationship between environmental and individual-specific constraints influence movement at various spatiotemporal scales. I concentrated my research on ungulates because of their vast distribution across multiple settings, their significant differences in life-history traits, and the availability of studies and GPS data from this taxonomic group. In the first part of my thesis, I summarized past research on the intraspecific drivers of home range size in ungulates and evaluated whether previous findings depend on the ecological traits of the species. Second, using data on 23 species and the robust framework of continuous-time stochastic movement models (CTMM), I investigated how female ungulates respond geographically to the spatial variation in productivity while accounting for the neonatal anti-predator tactic of their offspring. This should lead to a better understanding of the elements that influence the movement of animals during periods of high energy requirement when they have to balance their demands for safety and food. Third, I used the CTMM framework to determine the influence of mating tactics on the movement of male ungulates during the rut. I also provided a key metric that may be used to distinguish between the different mating tactics. All of the findings provided in this thesis have contributed to a better understanding of the variables that influence home range size and movement in various ungulate species at key moments of their biological cycle.; Parmi les nombreux comportements que présente un animal, le mouvement est l'une des principales composantes étudiées des organismes. L'étude des particularités du mouvement peut contribuer à notre compréhension des mécanismes reliant le comportement spatial à la démographie des populations. Les animaux doivent se déplacer dans le paysage pour sélectionner les habitats contenant les ressources nécessaires à leur survie et pour maximiser leur succès reproducteur. Choisir le bon habitat n'est cependant pas une tâche simple car les individus doivent tenir compte des prédateurs, des congénères et de la configuration du paysage pour décider comment et où se déplacer. De plus, le déplacement des animaux dans leur environnement peut dépendre de leurs caractéristiques morphologiques, physiologiques et écologiques. Jusqu'à présent, la plupart des études reliaient la taille du domaine vital et les déplacements à des variables environnementales, et peu d'entre elles reliaient ces deux composantes spatiales à l'état interne de l'animal. Au cours de ma thèse, j'ai tenté de résoudre cette question en évaluant comment la relation entre les contraintes environnementales et les contraintes spécifiques à l'individu influencent le mouvement à différentes échelles spatio-temporelles. J'ai concentré mes recherches sur les ongulés en raison de leur vaste distribution dans de multiples contextes, de leurs différences significatives dans les traits de l'histoire de vie, et de la disponibilité d'études et de données GPS de ce groupe taxonomique. Dans la première partie de ma thèse, j'ai résumé les recherches antérieures sur les facteurs intraspécifiques de la taille du domaine vital chez les ongulés et j'ai évalué si les résultats précédents dépendent des caractéristiques écologiques de l'espèce. Ensuite, en utilisant des données sur 23 espèces et en profitant du cadre robuste des modèles de mouvement stochastiques à temps continu (CTMM), j'ai étudié comment les femelles ongulées répondent géographiquement à la variation spatiale de la productivité tout en tenant compte de la tactique néonatale anti-prédateur de leurs petits. Cela devrait permettre de mieux comprendre les éléments qui influencent le mouvement des animaux pendant les périodes de besoin énergétique élevé où ils doivent équilibrer leurs demandes de sécurité et de nourriture. Troisièmement, j'ai utilisé le cadre CTMM pour déterminer l'influence des tactiques d'accouplement sur les mouvements des ongulés mâles pendant le rut. J'ai également fourni une métrique clé qui peut être utilisée pour distinguer les différentes tactiques d'accouplement. Tous les résultats fournis dans cette thèse ont contribué à une meilleure compréhension des variables qui influencent la taille du domaine vital et les mouvements chez diverses espèces d'ongulés à des moments clés de leur cycle biologique.

Among the pollutants present in the troposphere, ozone (O3) is probably one of the most stressful for organisms, owing to its strong oxidizing potential. For example, high concentrations of O3 ([O3]) can affect the emission of volatile organic compounds (VOCs) that allow plants to communicate with their environment. Moreover, O3 can react with these VOCs in the atmosphere to create new molecules, thus degrading the chemical signals upon which plant-insect interactions, including plant-pollinator interactions, depend. Many studies have shown the effects of O3 on the vegetative parts of plants but very few have studied their effects on their reproductive parts, which are generally responsible for the attraction of pollinators. This work therefore aims to provide knowledge on the effect of O3 in plant-pollinator chemical communication, namely, its effects on (i) the emission of floral VOCs by the plant, (ii) the chemical signal during its transport in the atmosphere and (iii) the recognition of this signal by pollinators.In the Mediterranean region, the interactions between the Mediterranean fig tree, Ficus carica (Moraceae), and its specific pollinator, Blastophaga psenes (Agaonidae), and between the true lavender, Lavandula angustifolia (Lamiaceae), and its generalist pollinator, the honeybee, Apis mellifera (Apidae), are the two emblematic study models chosen to meet the objectives of this dissertation, owing to their specificity and to the frequency and intensity of O3 pollution peaks in this region.This work combined descriptive and experimental studies to determine (i) the daily rate of VOCs emission from flowering plants, (ii) the in natura variation in emission of floral VOCs from fig trees exposed chronically or punctually to O3 pollution and other variables affected by climate change, (iii) the response of plants exposed under controlled conditions to a peak of O3 pollution, in terms of their emission of floral VOCs, (iv) the reaction of O3 with floral VOCs in a controlled atmosphere, and (v) the consequences of these two effects on the attraction of pollinators.The results show that (i) for both models, VOCs emission is correlated with light intensity but also shows different emission peaks during the day, depending on identity of the VOCs; (ii) for F. carica, there is marked seasonal variation in the emission of VOCs in natura, with light intensity, temperature, drought and chronic and acute source of O3 pollution responsible for variations in the emission of floral VOCs; (iii) for both species, exposure under controlled conditions for 5h to 200 ppb O3 (maximum ([O3] recorded in the last 15 years in the Mediterranean region) has no immediate effect on emission of floral VOCs, but (iv) floral VOCs alone exposed to different [O3] react differentially with the pollutant to form new molecules, thus modifying the proportions of VOCs in the mixture at [O3] as low as 40 ppb, and finally, (v) in F. carica, these modifications of VOCs significantly inhibit the attraction of the specific pollinator. This study highlights sources of variation in floral VOC emission in the two model species but also provides an integrative view of the effect of acute exposure to high [O3] on the concentration of VOCs around these plants. Behavioral tests with different pollinators are now essential to characterize the resilience of these interactions to the [O3]-induced variations in VOCs highlighted in this study. More generally, this work points to the importance of studying factors of climate change co-occurring in natura, including the effects of the concentrations of different air pollutants, on chemical communication in different plant-pollinator interactions in order to define measures to protect these interactions in the face of current and future environmental changes., Parmi les polluants présents dans la troposphère, l’ozone (O3) est probablement l’un des plus stressant pour les organismes, du fait de son fort potentiel oxydant. Par exemple, de fortes concentrations d’O3 ([O3]) peuvent affecter l’émission des composés organiques volatils (COVs) permettant aux plantes de communiquer avec leur environnement. De plus, l’O3 peut réagir avec ces COVs dans l’atmosphère pour créer de nouvelles molécules, modifiant ainsi le signal chimique émis par les plantes. Or, ce signal est déterminant dans les interactions plantes-insectes. De nombreuses études ont montré les effets de l’O3 sur les parties végétatives des plantes mais très peu se sont intéressées aux parties reproductives, généralement responsables de l’attraction des pollinisateurs. L’objectif de cette thèse est donc d’améliorer nos connaissances sur l’effet de l’O3 dans les étapes de la communication chimique plantes-pollinisateurs, à savoir (i) l’émission par la plante des COVs floraux, (ii) le signal chimique lors de son transport dans l’atmosphère et (iii) la reconnaissance de ce signal par les pollinisateurs.En Méditerranée, les interactions entre le figuier méditerranéen, Ficus carica (Moraceae), et son pollinisateur très spécifique, Blastophaga psenes (Agaonidae), et entre la lavande vraie, Lavandula angustifolia (Lamiaceae) et son pollinisateur très généraliste l’abeille domestique, Apis mellifera (Apidae), sont les deux modèles d’études emblématiques choisis pour répondre aux objectifs de cette thèse, de par leur degré de spécificité, et la fréquence et l’intensité des pics de pollution à l’O3 dans cette région.Ces travaux de thèse ont combiné des études descriptives et expérimentales afin de déterminer (i) le rythme journalier d’émission des COVs chez la lavande et le figuier, (ii) les variations in natura d’émission des COVs floraux de figuiers exposés de façon chronique ou ponctuelle à une pollution à l’O3 et à d’autres facteurs du changement climatique, (iii) la réponse des deux espèces exposées, en conditions contrôlées, à un pic de pollution à l’O3 en terme d’émission de leurs COVs floraux, (iv) la réaction de l’O3 avec les COVs floraux dans une atmosphère contrôlée et (v) les conséquences de ces deux effets sur l’attraction de leurs pollinisateurs.Les résultats mettent en évidence (i) pour les deux modèles, un rythme d’émission de COVs a priori corrélé à l’intensité lumineuse mais avec différents pics d’émission dans la journée selon les COVs ; (ii) pour le figuier, une variation saisonnière très marquée de l’émission des COVs floraux in natura, en lien avec la température, la sécheresse et les pollutions chroniques et ponctuelles à l’O3 ; (iii) qu’une exposition en conditions contrôlées des deux espèces pendant 5 h à 200 ppb d’O3 ([O3] maximale répertoriée dans les 15 dernières années en méditerranée) n’a pas d’effets immédiats sur l’émission de leurs COVs floraux, mais que (iv) ces COVs seuls exposés à différentes [O3] réagissent différentiellement avec l’O3 pour former de nouvelles molécules, ceci faisant varier les proportions de COVs dans le mélange dès 40 ppb d’O3, et enfin, (v) chez le figuier, que ces variations de COVs inhibent l’attraction du pollinisateur. Cette étude a mis en évidence des sources de variations dans l’émission des COVs floraux chez les deux espèces modèles mais a également permis d’avoir une vision intégrative de l’effet d’un pic de pollution à l’O3 sur la concentration des COVs autour de ces plantes. Plus généralement, ces travaux de thèse soulignent l’importance d’étudier les facteurs du changement climatique co-occurant in natura, notamment les effets de la concentration de différents polluants atmosphériques, sur la communication chimique dans différentes interactions plantes-pollinisateurs afin de mettre en place des mesures de protection de ces interactions face aux changements environnementaux actuels et futurs.

The unprecedented health crisis we have been through has highlighted a unique category of women and men: essential workers (Lazar et al., 2020). Among these actors, farmers occupy a special place. Indeed, the tensions observed during the first lockdown highlighted the centrality of their work, between issues of productive sovereignty (Cohen, 2020; De Boissieu, 2020; Dumont, 2020; Gaillard, 2020), place of a local food offer, accessible and available (Neveu, 2020; Rastoin, 2020) and environmental challenges. Covid-19 has put our society in front of the limits of a productivist and intensive agricultural model that has become obsolete, and in this context, organic farmers are an interesting population for several reasons. While it enjoys a generally positive social perception and has benefited from renewed consumer interest (FranceAgriMer, 2020), it is not free from criticism, such as the supposed impossible access to all (scarcity) and for all (high cost) of its products (Kressman, 2021). The analysis of the discourse of these committed actors highlights many role strain (Katz and Kahn, 1966; Perrot, 2000; Djabi and Perrot, 2016; Arras-Djabi and al., 2021), inviting us to consider the agriculture we want at the dawn of a post-covid society. It also questions our expectations and paradoxes of organic farmers., La crise sanitaire inédite que nous avons traversée a mis en lumière une catégorie singulière de femmes et d’hommes : les travailleuses et les travailleurs essentiels (Lazar et al., 2020). Parmi ces acteurs, les agricultrices et agriculteurs occupent une place à part. En effet, les tensions observées à l’occasion du premier confinement ont mis en lumière la centralité de leur travail, entre enjeux de souveraineté productive (Cohen, 2020 ; De Boissieu, 2020 ; Dumont, 2020 ; Gaillard, 2020), place d’une offre alimentaire de proximité, accessible et disponible (Neveu, 2020 ; Rastoin, 2020) et défis environnementaux. Le Covid-19 a mis notre société face aux limites d’un modèle agricole productiviste et intensif devenu obsolète, et dans ce contexte, les agricultrices et agriculteurs biologiques constituent une population intéressante à plusieurs titres. Si elle jouit d’une perception sociale globalement positive et a bénéficié du regain d’intérêt des consommateurs (FranceAgriMer, 2020), elle n’est pas exempte de critiques, telles le supposé impossible accès à tous (rareté) et pour tous (cherté) de ses produits (Kressman, 2021). L’analyse du discours de ces acteurs engagés met en lumière des tensions de rôle (Katz et Kahn, 1966 ; Perrot, 2000 ; Djabi et Perrot, 2016 ; Arras-Djabi et al., 2021) nombreuses, nous invitant à réfléchir à l’agriculture que nous voulons à l’aube d’une société post-covid. Elle interroge aussi nos attentes et nos paradoxes à l’égard des agricultrices et agriculteurs biologiques.

National audience