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International audience; The seasonal beach rotation visible in Sakouli beach reflects : the two distinct hydrodynamic conditions that occur in Mayotte and a residual longshore sediment transport favored by a low bay indentation. However, the island subsidence of 10 to 20 cm since 2018 may have an impact over this equilibrium. Indeed, this could lead to higher wave energy over the beach. So, study must be continued and extended to several other beaches on the island.

Strengthening of feed security in the Sahel is urgently needed given the climate change and growing human population. A prerequisite to this is sustainable use of rangeland forage resources for livestock. Many studies have focused on the assessment of rangeland resources during the rainy season, while only a few have focused on the dry season which is the longest and most demanding period for livestock in Sahelian rangelands. The objective of this study is to develop remote sensing-based models for estimating dry season forage vegetation mass. To that end, 29 vegetation indices calculated from each of the MODIS-MCD43A4 (500 m), Landsat-8 (30 m), and Sentinel-2 (10 m) satellite products were used and tested against in situ data collected during three field-measurement campaigns in 2021 at eleven monitoring sites across Senegalese rangelands. Four statistical models were tested, namely, random forest, gradient boosting machines, and simple linear and multiple linear regressions. The two main vegetation mass variables modeled from remote sensing imagery were the standing herbaceous and litter dry mass (BH) and total forage dry mass (BT) with a dry mass of woody plant leaves added to BH. Overall, Sentinel-2 data provided the best performance for the assessment of BH with multiple linear regression (R2 = 0.74; RMSE = 378 kg DM/ha) using NDI5 (Normalized Difference Index5), GRCI (Green Residue Cover Index), SRI (Simple Ratio Index), TCARI (Transformed Chlorophyll Absorption in Reflectance Index), and DFI (Dead Fuel Index) indices. For BT, the best model was also obtained from Sentinel-2 data, including RVI3 (Ratio Vegetation Index3) (R2 = 0.78; RMSE = 496 kg DM/ha). Results showed the suitability of combining the red, green, blue, NIR, SWIR1, and SWIR2 bands in monitoring forage availability during the dry season. Our study revealed that the spectral richness of the optical sensor systems Sentinel-2, Landsat-8, and MODIS-MCD43A4 allowed for accurate assessments of dry-season forage mass of semi-arid rangelands. Adding to this, the high spatial and temporal resolution of Sentinel-2 satellite imagery makes this a promising data source for timely monitoring. These findings can support the monitoring of the animal feed balance in Sahelian countries and contribute to enhancing the resilience of pastoralism toward feed shortage through early warning systems.

Polar regions are characterized by rocky terrains with sparse vegetation and oligotrophic soils, i.e. “fellfields”. In such ecosystems, microbial communities should be essential for soil-plant functioning but their diversity is poorly explored. The sub-Antarctic Kerguelen Islands fellfields are characterized by an endemic long-lived cushion plant, Lyallia kerguelensis which rhizosphere may be a shelter for microbes in this harsh environment. Cushions are affected by necrosis and we expect the rhizomicrobiome composition to be related to plant necrosis. We analysed bacterial and fungal communities in bulk- and rhizospheric soils from L. kerguelensis in five different fellfields across the Kerguelen Islands using 16S rRNA and ITS1 metabarcoding. We found that soil microbial communities were composed of both restricted and cosmopolitan taxa. While all sites were dominated by the same bacterial taxa (Chloroflexi, Actinobacteria, α-Proteobacteria and Acidobacteria), the relative abundance of the main fungal phyla (Ascomycota, Basidiomycota, Mortierellomycota and Rozellomycota) highly differed between sites. L. kerguelensis rhizomicrobiome was at least as diverse as the bulk soil, making the rhizosphere a possible reservoir of microbial diversity. It was composed of the same main bacterial phyla than detected in the bulk soil while the composition of the rhizosphere fungal communities was specific to each plant. No common microorganisms were identified regarding cushion necrosis extent across plants and sites, but several microbial putative functions were shared, suggesting a possible shift in soil functioning with cushion necrosis increase. Our study brings new information on the diversity and composition of the microbial communities of fellfield soils in a sub-Antarctic Island and the rhizomicrobiome of a characteristic endemic cushion plant.

In the context of global changes, it is crucial to understand how ecosystems react to anthropic pressures. Theoretical ecology has already largely studied how populations recover from perturbations, but it still relies on relatively simple systems, which are typically isolated in space and species-poor. This thesis tackles this issue by investigating whether considering space explicitly affects our current understanding of ecosystem stability. More specifically, we explore the interplay between the spatial structure of perturbations and the spatial structure of the landscape and its effects on the response of meta-populations and meta-communities to disturbances.In the first chapter, we use laboratory microcosm experiments coupled with a mathematical model to study how the number and spatial clustering of local extinctions affects the dynamics of metacommunities. In particular, we focus on patterns of species diversity and show that local extinctions can increase both local and inter-patch diversity, but that the contribution to each level of diversity depends largely on the spatial structure of extinctions. In the second chapter, we investigate the impact of a metapopulation's spatial structure on its stability. We focus on spatially explicit metapopulations in which local dynamics are bistable and explore the resulting landscape-scale stability. We show that local catastrophic shifts can spread in space until they affect the whole metapopulation, and that local bistability results in landscape-scale bistability with a strong hysteresis. We highlight that the size of the hysteresis depends strongly on the metapopulation spatial structure and that previous studies using a simple one-dimensional spatial structure had underestimated the hysteresis than can be observed in more realistic landscapes. In the third chapter, we reflect on which layers of complexity should be considered to better understand catastrophic shifts by reviewing existing work and highlighting promising approaches for future developments. In the fourth chapter, we present such an approach that allows to reduce the dynamics of a spatially-structured metapopulation to a single dimension.We investigate how well this reduction works in metapopulations with different structures (random, modular, dendritic), and show that the landscape-scale equilibria and temporal variability of complex spatial networks can effectively be predicted by a one-dimensional equation.; Dans un contexte de changements globaux, il est crucial de comprendre comment les écosystèmes réagissent aux pressions anthropiques. L'écologie théorique a déjà beaucoup étudié comment les systèmes écologiques se régénèrent suite à des perturbations, mais elle s'appuie encore sur des systèmes relativement simples, qui sont typiquement isolés dans l'espace et comportent peu d'espèces.Cette thèse aborde cette problématique en étudiant si la prise en compte de l'espace de manière explicite affecte notre compréhension actuelle de la stabilité des écosystèmes. Plus précisément, nous explorons l'interaction entre la structure spatiale des perturbations et la structure spatiale du paysage, et leurs effets sur la réponse des méta-populations et des méta-communautés aux perturbations.Dans le premier chapitre, nous utilisons des expériences en microcosmes couplées à un modèle mathématique pour étudier comment le nombre et l'organisation spatiale d'extinctions locales affectent la dynamique des métacommunautés. En particulier, nous nous concentrons sur les patrons de diversité des espèces et montrons que les extinctions locales peuvent augmenter à la fois la diversité locale et inter-patch, mais que la contribution à chaque niveau de diversité dépend largement de la structure spatiale des extinctions. Dans le deuxième chapitre, nous étudions l'impact de la structure spatiale d'une métapopulation sur sa stabilité. Nous nous concentrons sur des métapopulations structurées spatialement dans lesquelles les dynamiques locales sont bistables et nous explorons la stabilité qui en résulte à l'échelle du paysage. Nous montrons que des transitions catastrophiques locales peuvent se propager dans l'espace jusqu'à affecter l'ensemble de la métapopulation, et que la bistabilité locale entraîne une bistabilité à l'échelle du paysage avec une forte hystérèse. Nous soulignons que l'ampleur de l'hystérèse dépend fortement de la structure spatiale de la métapopulation et que les études précédentes qui étudient le cas d'une structure spatiale unidimensionnelle simple sous-estiment l'hystérèse qui peut être observée dans des paysages plus réalistes. Dans le troisième chapitre, nous discutons des aspects de la complexité qui devraient être pris en compte pour mieux comprendre les transitions catastrophiques. Nous passons en revue les travaux existants et soulignons des approches prometteuses pour de futurs développements. Dans le quatrième chapitre, nous présentons une telle approche qui permet de réduire la dynamique d'une métapopulation spatialement structurée à une seule dimension. Nous étudions l'efficacité de cette réduction dans des métapopulations avec différentes structures spatiales, et nous montrons que les équilibres à l'échelle du paysage et la variabilité temporelle de réseaux spatiaux complexes peuvent effectivement être prédits par une équation unidimensionnelle.

Background Understanding how behavioural dynamics, inter-individual variability and individual interactions scale-up to shape the spatial spread and dispersal of animal populations is a major challenge in ecology. For biocontrol agents, such as the microscopic Trichogramma parasitic wasps, an understanding of movement strategies is also critical to predict pest-suppression performance in the field. Methods We experimentally studied the spatial propagation of groups of parasitoids and their patterns of parasitism. We investigated whether population spread is density-dependent, how it is affected by the presence of hosts, and whether the spatial distribution of parasitism (dispersal kernel) can be predicted from the observed spread of individuals. Using a novel experimental device and high-throughput imaging techniques, we continuously tracked the spatial spread of groups of parasitoids over large temporal and spatial scales (8 h; and 6 m, ca. 12,000 body lengths). We could thus study how population density, the presence of hosts and their spatial distribution impacted the rate of population spread, the spatial distribution of individuals during population expansion, the overall rate of parasitism and the dispersal kernel (position of parasitism events). Results Higher population density accelerated population spread, but only transiently: the rate of spread reverted to low values after 4 h, in a “tortoise-hare” effect. Interestingly, the presence of hosts suppressed this transiency and permitted a sustained high rate of population spread. Importantly, we found that population spread did not obey classical diffusion, but involved dynamical switches between resident and explorer movement modes. Population distribution was therefore not Gaussian, though surprisingly the distribution of parasitism (dispersal kernel) was. Conclusions Even homogenous asexual groups of insects develop behavioural heterogeneities over a few hours, and the latter control patterns of population spread. Behavioural switching between resident and explorer states determined population distribution, density-dependence and dispersal. A simple Gaussian dispersal kernel did not reflect classical diffusion, but rather the interplay of several non-linearities at individual level. These results highlight the need to take into account behaviour and inter-individual heterogeneity to understand population spread in animals.

Background To encourage Covid-19 vaccination, France introduced during the Summer 2021 a ‘Sanitary Pass’, which morphed into a ‘Vaccine Pass’ in early 2022. While the sanitary pass led to an increase in Covid-19 vaccination rates, spatial heterogeneities in vaccination rates remained. To identify potential determinants of these heterogeneities and evaluate the French sanitary and vaccine passes’ efficacies in reducing them, we used a data-driven approach on exhaustive nationwide data, gathering 141 socio-economic, political and geographic indicators. Methods We considered the association between vaccination rates and each indicator at different time points: before the sanitary pass announcement (week 2021-W27), before the sanitary pass came into force (week 2021-W31) and 1 month after (week 2021-W35) and the equivalent dates for the vaccine pass (weeks 2021-W49, 2022-W03 and 2022-W07). Results The indicators most associated with vaccination rates were the share of local income coming from unemployment benefits, overcrowded households rate, immigrants rate and vote for an ‘anti-establishment’ candidate at the 2017 Presidential election. These associations increase over time. Consequently, living in a district below the median of such indicator decreases the probability to be vaccinated by about 30% at the end of the studied period, and this probability gradually decreases by deciles of these indicators. Conclusions Our analysis reveals that factors related to poverty, immigration and trust in the government are strong determinants of vaccination rate, and that vaccination inequities tended to increase after the introduction of the French sanitary and vaccination passes.

Pascal Mouquet - IRD (UMR Espace-Dev) - Tuteur de stageChristophe Révillion - Université de La Réunion (UMR Espace-Dev) - Tuteur de stageJean-Pierre Chery - AgroParisTech - Enseignant-référant; National audience; Coral reefs act as barriers that protect the coastline from strong swells and surges. Due to anthropogenic pressures and intensified cyclonic swells, the vulnerability of these ecosystems increases. It is therefore essential to understand how reefs are maintained to assess their ability to protect coastal populations and ecosystems. To this end, the research lab ENTROPIE is conducting hydrochemical samplings on the Saint-Gilles reef in Reunion Island, a reef that is particularly exposed to the cyclones affecting the island and to anthropogenic pressures. As part of the multidisciplinary research project ReNovRisk-Transferts, this study, coordinated by Espace-Dev lab, evaluates the potential of multispectral satellite imagery to study the maintenance of coral reefs in relation to in situ hydrochemical measurements. Our results highlight the possibility of mapping live coral cover from Pleiades or SPOT imagery using a BIBG brightness index. The values produced by this index are sufficiently correlated with reference (R² = 0.53) and field (R² = 0.52) coral cover values to be considered valid. However, the low spectral resolution of multispectral imagery hinders the clear distinction of coral and photosynthetic organisms. This limitation must be considered when using this methodology for reef substrate mapping. This study also proposes a methodological approach to extrapolate hydrochemical point estimates of reef maintenance (carbonate budget) to the entire reef. This approach is the result of an interdisciplinary reflection and offers an innovative approach that requires the mapping of only one substrate, the coral cover, to establish a general carbonate budget. Future studies may test its validity.; Les récifs coralliens agissent comme des barrières qui protègent le littoral des fortes houles et de la surcote. Face aux pressions anthropiques et à l’intensification des houles cycloniques, la vulnérabilité de ces écosystèmes est accrue. Il est donc essentiel de comprendre comment se maintiennent les récifs pour évaluer leur capacité à protéger les populations et les écosystèmes côtiers. Pour ce faire, l’UMR ENTROPIE effectue des mesures hydrochimiques ponctuelles sur le récif de Saint-Gilles à La Réunion, récif particulièrement exposé aux cyclones touchant l’île et aux pressions anthropiques. Dans le cadre du projet multidisciplinaire ReNovRisk-Transferts, cette étude, avec l’UMR Espace- Dev, propose d’évaluer le potentiel de l’imagerie satellitaire multispectrale pour étudier le maintien des récifs coralliens en lien avec les mesures in situ hydrochimiques. Nos résultats mettent en évidence la possibilité d’effectuer une cartographie de la couverture corallienne vivante à partir de l’imagerie Pléiades ou SPOT en utilisant l’indice de brillance BIBG. Les valeurs produites par cet indice sont suffisamment corrélées avec les valeurs de couverture corallienne de référence (R² = 0,53) et de terrain (R² = 0,52) pour être considérées comme valides. La faible résolution spectrale de l’imagerie multispectrale entrave toutefois la nette distinction des organismes coralliens et des autres organismes photosynthétiques. Cette limite doit être prise en compte lors de l’utilisation de cette méthodologie pour la cartographie des substrats récifaux. Cette étude propose également une démarche méthodologique pour extrapoler les estimations ponctuelles hydrochimiques de maintien du récif (bilan des carbonates) à l’ensemble du récif. Cette démarche est issue d’une réflexion interdisciplinaire et offre une approche innovante qui ne nécessite la cartographie que d’un seul composant du fond, la couverture corallienne, pour établir un bilan des carbonates général. Des études et travaux futurs pourront tester sa validité.

International audience; While some works have suggested that large-scale mobilities and conflicts in Central Asia and Western Asia (e.g. Mongol invasions) have been linked to climatic events, in this contribution we choose to move the focus to local human-climate interactions. We will specifically investigate what were the adaptation strategies of agropastoral systems vis-à-vis water stress, in the frame of various political constructions, over the last 1500 years. Based on palaeohydrological and paleoecological investigations carried out on selected lake sedimentary archives of Iran and Uzbekistan, we will reconstruct the long-term variability of lake evaporation and runoff processes (sedimentology, geochemistry), together with indicators on the nature and relative intensity of the agropastoral practices (palynology). Those results will be put into a Human perspective through comparisons with historical sources. In particular, we will propose a special focus on the Medieval Islamic Period to discuss the hypotheses that regional climate changes, by modifying water resource availability locally, might have impacted crops and pastoral livestock productions, triggering economic losses and social contestations unevenly addressed by the succeeding political powers.

Riparian zones are the paragon of transitional ecosystems, providing critical habitat and ecosystem services that are especially threatened by global change. Following consultation with experts, 10 key challenges were identified to be addressed for riparian vegetation science and management improvement: (1) Create a distinct scientific community by establishing stronger bridges between disciplines; (2) Make riparian vegetation more visible and appreciated in society and policies; (3) Improve knowledge regarding biodiversity—ecosystem functioning links; (4) Manage spatial scale and context-based issues; (5) Improve knowledge on social dimensions of riparian vegetation; (6) Anticipate responses to emergent issues and future trajectories; (7) Enhance tools to quantify and prioritize ecosystem services; (8) Improve numerical modeling and simulation tools; (9) Calibrate methods and increase data availability for better indicators and monitoring practices and transferability; and (10) Undertake scientific validation of best management practices. These challenges are discussed and critiqued here, to guide future research into riparian vegetation. This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Water and Life > Stresses and Pressures on Ecosystems Water and Life > Conservation, Management, and Awareness

International audience; Holopelagic Sargassum blooms in the tropical North Atlantic since 2011 are composed of two species, Sargassum natans and S. fluitans, and three morphotypes: S. natans VIII, S. natans I and S. fluitans III. The distinct morphology and the variations in space and time of the proportion of these three morphotypes suggest that they may have different physiology. For the first time, we have quantified the growth rates of these three morphotypes through in situ 9-day experiments on the coast of Martinique Island (French West Indies). Despite the non-optimal conditions for growth for these pelagic species and the short time of the experiment, we have observed that Sargassum fluitans III was growing faster (approximately twice as fast) than S. natans VIII and S. natans I. Sargassum natans I exhibited the slowest growth. The differences in tissue composition (CNP and CN natural isotopes) of morphotypes point to a greater benefit for S. fluitans III from the coastal localization of our experiment than for the two S. natans morphotypes, and suggest that S. natans I had achieved its last growth further offshore before our experiment. These contrasting growth performances are consistent with the dominance of S. fluitans III in recent observations in the Caribbean region and along the path from the Sargassum belt. This also makes this last morphotype the best candidate for cultivation. Making the distinction between the growth performances of morphotypes may improve the current predictive models about dispersal of these species.

International audience; A risk assessment for disasters is usually composed of hazard, vulnerability and exposure variables, which are hardly studied and modeled simultaneously. In volcanology, it remains ambitious to anticipate risk trajectories of pre- and post-eruption regimes. The interdependencies and feedback loops of the system's components, between geological, ecological, social and economic ones, give rise to trade-offs and synergies that should be disentangled for supporting decision-makers and helping local communities to face the risks. We developed here an innovative discrete-event and possibilistic model based on a dynamical network representation to assess volcanological multi-risk and long term post-eruption impacts of such a multifactorial system. We illustrated our method with the region around Mount Meru (Northern Tanzania), a strato-volcano with various eruption styles, located in a growing economic and touristic region (>1 M.inh.). We used qualitative and rule-based Petri nets, largely unused in environmental sciences, for an integrated assessment of the overall system dynamics and associated risks. As a central result, we showed that the region could recover from a blast eruption, irrespective of the timescale. Our study highlights the fact that agriculture and pastoralism remain key activities to favour the recovery of this region. Yet, as soon as subsidies from governmental and non-governmental organizations are lacking, the modeled region remains isolated from national and international activities and shifts to rural dynamics. Our case study can equip environmental risk assessment with innovative models, new dynamical indices (e.g. desirable and non-desirable trajectories), and rigorous reasoning for an ultimate integrated management of social-ecological systems at stake.

L'écopastoralisme est une pratique de gestion écologique en plein essor, dont les bienfaits pour le maintien ou la restauration des milieux naturels ont été largement démontrés. Mais cette solution alternative de gestion obtient-elle les mêmes résultats sur des milieux fortement anthropisés et artificialisés ? Une étude menée sur les digues artificielles du Rhône de la réserve de chasse de Donzère-Mondragon s'est intéressée aux impacts des différents troupeaux sur les communautés végétales d’écosystèmes récents. Grâce à un suivi botanique sur plusieurs années, les scientifiques ont pu démontrer que la gestion par les herbivores s'avérait efficace pour maintenir l'ouverture des milieux et augmenter significativement le nombre et la diversité des espèces par rapport à l’absence de gestion ou aux interventions mécaniques.

Primary forests, defined here as forests where the signs of human impacts, if any, are strongly blurred due to decades without forest management, are scarce in Europe and continue to disappear. Despite these losses, we know little about where these forests occur. Here, we present a comprehensive geodatabase and map of Europe’s known primary forests. Our geodatabase harmonizes 48 different, mostly field-based datasets of primary forests, and contains 18,411 individual patches (41.1 Mha) spread across 33 countries. When available, we provide information on each patch (name, location, naturalness, extent and dominant tree species) and the surrounding landscape (biogeographical regions, protection status, potential natural vegetation, current forest extent). Using Landsat satellite-image time series (1985–2018) we checked each patch for possible disturbance events since primary forests were identified, resulting in 94% of patches free of significant disturbances in the last 30 years. Although knowledge gaps remain, ours is the most comprehensive dataset on primary forests in Europe, and will be useful for ecological studies, and conservation planning to safeguard these unique forests., Measurement(s)Geographic DistributionTechnology Type(s)digital curationFactor Type(s)countrySample Characteristic - Environmentprimary forestSample Characteristic - LocationEurope Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.14540625

International audience; The intensification of biological processes coping with salt stress became a major issue to mitigate land degradation. The Sine-Saloum Delta in Senegal is characterized by salt-affected soils with vegetation dominated by salt-tolerant grass Sporobolus robustus and shrubs like Prosopis juliflora. Plant experiments in controlled conditions suggested that arbuscular mycorrhizal (AM) fungi might be the key actors of facilitation process observed between S. robustus and P. juliflora, but the AM fungal community determinants are largely unknown. The current field-based study aimed at (1) characterizing the environmental drivers (rhizosphere physico-chemical properties, plant type and season) of the AM fungal community along an environmental gradient and (2) identifying the AM fungal taxa that might explain the S. robustus-mediated benefits to P. juliflora. Glomeraceae predominated in the two plants, but a higher richness was observed for S. robustus. The pH and salinity were the main drivers of AM fungal community associated with the two plants, negatively impacting richness and diversity. However, while a negative impact was also observed on mycorrhizal colonization for S. robustus, P. juliflora showed opposite colonization patterns. Furthermore, no change was observed in terms of AM fungal community dissimilarity between the two plants along the environmental gradient as would be expected according to the stress-gradient and complementary hypotheses when a facilitation process occurs. However, changes in intraspecific diversity of shared AM fungal community between the two plants were observed, highlighting 23 AM fungal OTUs associated with both plants and the highest salinity levels. Consequently, the increase of their abundance and frequency along the environmental gradient might suggest their potential role in the facilitation process that can take place between the two plants. Their use in ecological engineering could also represent promising avenues for improving vegetation restoration in saline Senegalese's lands.

International audience; Amazonian rainforests, once thought to be pristine wilderness, are increasingly known to have been widely inhabited, modified, and managed prior to European arrival, by human populations with diverse cultural backgrounds. Amazonian Dark Earths (ADEs) are fertile soils found throughout the Amazon Basin, created by pre-Columbian societies with sedentary habits. Much is known about the chemistry of these soils, yet their zoology has been neglected. Hence, we characterized soil fertility, macroinvertebrate communities, and their activity at nine archeological sites in three Amazonian regions in ADEs and adjacent reference soils under native forest (young and old) and agricultural systems. We found 673 morphospecies and, despite similar richness in ADEs (385 spp.) and reference soils (399 spp.), we identified a tenacious pre-Columbian footprint, with 49% of morphospecies found exclusively in ADEs. Termite and total macroinvertebrate abundance were higher in reference soils, while soil fertility and macroinvertebrate activity were higher in the ADEs, and associated with larger earthworm quantities and biomass. We show that ADE habitats have a unique pool of species, but that modern land use of ADEs decreases their populations, diversity, and contributions to soil functioning. These findings support the idea that humans created and sustained high-fertility ecosystems that persist today, altering biodiversity patterns in Amazonia.

Context Evidence for effects of habitat loss and fragmentation on the viability of temperate forest herb populations in agricultural landscapes is so far based on population genetic studies of single species in single landscapes. However, forest herbs differ in their life histories, and landscapes have different environments, structures and histories, making generalizations difficult. Objectives We compare the response of three slow-colonizing forest herbs to habitat loss and fragmentation and set this in relation to differences in life-history traits, in particular their mating system and associated pollinators. Methods We analysed the herbs’ landscape-scale population genetic structure based on microsatellite markers from replicate forest fragments across seven European agricultural landscapes. Results All species responded to reductions in population size with a decrease in allelic richness and an increase in genetic differentiation among populations. Genetic differentiation also increased with enhanced spatial isolation. In addition, each species showed unique responses. Heterozygosity in the self-compatible Oxalis acetosella was reduced in smaller populations. The genetic diversity of Anemone nemorosa, whose main pollinators are less mobile, decreased with increasing spatial isolation, but not that of the bumblebee-pollinated Polygonatum multiflorum. Conclusions Our study indicates that habitat loss and fragmentation compromise the long-term viability of slow-colonizing forest herbs despite their ability to persist for many decades by clonal propagation. The distinct responses of the three species studied within the same landscapes confirm the need of multi-species approaches. The mobility of associated pollinators should be considered an important determinant of forest herbs’ sensitivity to habitat loss and fragmentation.

Animal movement has been identified as a key feature in understanding animal behavior, distribution and habitat use and foraging strategies among others. Large datasets of invididual locations often remain unused or used only in part due to the lack of practical models that can directly infer the desired features from raw GPS locations and the complexity of existing approaches. Some of them being disputed for their lack of biological justifications in their design. We propose a simple model of individual movement with explicit parameters, based on a two-dimensional biased and correlated random walk with three forces related to advection (correlation), attraction (bias) and immobility of the animal. These forces can be directly estimated using individual data. We demonstrate the approach by using GPS data of 5 red deer with a high frequency sampling. The results show that a simple random walk template can account for the spatial complexity of wild animals. The practical design of the model is also verified for detecting spatial feature abnormalities and for providing estimates of density and abundance of wild animals. Integrating even more additional features of animal movement, such as individuals’ interactions or environmental repellents, could help to better understand the spatial behavior of wild animals.

International audience; The traditional view of sex roles and sexual selection emphasises the evolution of male ornaments as a result of female mate choice and male-male competition. Female ornaments are now receiving more attention, although their roles in mating decisions are still less well understood, especially considering cases in which colourful ornaments are expressed by both sexes. In this study, we analysed whether female skin coloration (luminance and redness of the face and hindquarters) influenced male mate choice and sexual behaviours in relation to intracycle (cycle phase), inter-cycle (number of consecutive cycles, conceptive nature of the cycle), and inter-individual (age, social rank, weight, and parity) variation in a captive social group of Japanese macaques (Macaca fuscata). Males did not preferentially choose darker/redder females. Moreover, males did not appear to use female skin coloration to apportion their mating efforts on the fertile phase of the menstrual cycle or during cycles that lead to conception, or to discriminate between females. Collectively, our results suggest that female skin coloration may not have been sexually selected in this species and that males mated regardless of such variation across females. To our knowledge, our study is among the few to report a lack of male choice for female coloration in a species where both sexes display ornamentation. Our findings provide novel insights on the role and evolution of female coloration in sexual signalling and mating decisions.

International audience; Harvesting may drive body downsizing along with population declines and decreased harvesting yields. These changes are commonly construed as consequences of direct harvest selection, where small-bodied, early-reproducing individuals are immediately favoured. However, together with directly selecting against a large body size, harvesting and body downsizing alter many ecological features, such as competitive and trophic interactions, and thus also indirectly reshape natural selection acting back on body sizes through eco-evolutionary feedback loops (EEFLs). We sketch plausible scenarios of simple EEFLs in which one-dimensional, density-dependent natural selection acts either antagonistically or synergistically with direct harvest selection on body size. Antagonistic feedbacks favour body-size stasis but erode genetic variability and associated body-size evolvability, and may ultimately impair population persistence and recovery. In contrast, synergistic feedbacks drive fast evolution towards smaller body sizes and favour population resilience, but may have far-reaching bottom–up or top–down effects. We illustrate the further complexities resulting from multiple environmental feedbacks using a co-evolving predator–prey pair, in which case outcomes from EEFLs depend not only on population densities, but also on whether prey sit above or below the optimal predator/prey body-size ratio, and whether prey are more or less evolvable than their predators. EEFLs improve our ability to understand and predict nature's response to harvesting, but their integration into the research agenda will require a full consideration of the effects and dynamics of natural selection.

International audience; Aim Mountains host complex ecosystems whose wide range of ecological conditions over small geographical distances makes them biodiversity hotspots. To ensure their long-term conservation, a better understanding of the interaction between climate change and modifications in land use is necessary. Most studies have focused on only one of these factors at a time, leading to incomplete predictions. In this study, we explored the relative contribution of both recreative activities and climate change on the population dynamics of the black grouse (Tetrao tetrix), an emblematic cold-adapted species of the Alps.Methods We used data from a network of 47 monitoring sites dispersed around the French Alps and surveyed since the 1980s or 1990s. We estimated black grouse population growth rates using state-space models and tested for effects of biotic and abiotic pressures on both long-term trends and inter-annual variations in these rates.Results Population trajectories were strongly heterogeneous in space; nevertheless, a general decline at the edge of the black grouse distribution area was revealed in the southern pre-Alps. We found very little influence of hunting and new ski lift cables installation on inter-annual variability in population growth rate. In contrast, our results suggest strong impact of climatic conditions and phenology. While temperature positively influenced growth rate, precipitation had a negative effect. Early snowmelt and vegetation season were correlated with high positive values of annual population growth rates.Main conclusions Birds in mountain habitats may be drastically affected by ongoing climate change, perhaps to a greater extent than by an increase in recreational activities. However, other human activities in the mountains (such as animal grazing or forest exploitation) that were not taken into consideration in this study might also have a strong impact on habitat structure and indirectly affect populations' growth.

Summary The study presents a comparative analysis of eight Vegetation Indices (VIs) used to examine vegetation greenness over the northern coasts of Iceland. The geographical extent of the study area is set by the coordinates of the two fjords, Eyjafjörður and Skagafjörður, notable for their agricultural significance. Vegetation in Iceland is fragile due to the harsh climate, climate change, overgrazing and volcanic activity, which increase soil erosion. The study was conducted on a Landsat TM image using SAGA GIS as a technical tool for raster bands calculations. The NDVI dataset shows a range from -0.56 to 0.24, with 0 indicating ‘no vegetation’, and negative values – ‘other surfaces’ (e.g. rocks, open terrain). The DVI, compared to the NDVI, shows statistically non-normalized values ranging from -112 to 0, with extreme negative values while the coastal vegetation areas are badly distinguished from the water areas. The NRVI shows an extent from -0.24 to 0.48 with higher values for vegetation. The NRVI reduces topographic, solar and atmospheric effects and creates a normal data distribution. RVI shows a range in a dataset from 0.2 to 3.2 with vegetation in the river valleys clearly visible and depicted, while the water areas have values 0.8 to 1.0. The CTVI shows corrected TVI, in a data range -0.10 to 1.10, as the dataset of NDVI were negative. The TVI dataset ranges from 0.44 to 0.80 with the ice-covered areas and glaciers distinguishable and water values within a range from 0.60 to 0.64 and the vegetation from 0.60 to 0.44. The TTVI dataset ranges from 0.40 to 0.80 performing similarly to the TVI, but more refined with vegetation values 0.64 to 0.68. SAVI dataset ranges from -0.80 to 0.30 with minimized effects of soil on the vegetation through a constant soil adjustment factor added into the NDVI formula. The paper presents a comparison of eight VIs for Arctic vegetation monitoring. The overall behavior of SAGA GIS in calculation and mapping of the VIs is effective in terms of their use for vegetation mapping of the region.

Lakes are often described as sentinels of global change. Phenomena like lake eutrophication, algal blooms, or reorganization in community composition belong to the most studied ecosystem regime shifts. However, although regime shifts have been well documented in several lakes, a global assessment of the prevalence of regime shifts is still missing, and, more in general, of the factors altering stability in lake status, is missing. Here, we provide a first global assessment of regime shifts and stability in the productivity of 1,015 lakes worldwide using trophic state index (TSI) time series derived from satellite imagery. We find that 12.8% of the lakes studied show regime shifts whose signatures are compatible with tipping points, while the number of detected regime shifts from low to high TSI has increased over time. Although our results suggest an overall stable picture for global lake dynamics, the limited instability signatures do not mean that lakes are insensitive to global change. Modeling the interaction between lake climatic, geophysical, and socioeconomic features and their stability properties, we find that the probability of a lake experiencing a tipping point increases with human population density in its catchment, while it decreases as the gross domestic product of that population increases. Our results show how quantifying lake productivity dynamics at a global scale highlights socioeconomic inequalities in conserving natural environments., Proceedings of the National Academy of Sciences, 119 (35), ISSN:0027-8424, ISSN:1091-6490

International audience; Regular vegetation patterns have been predicted to indicate a system slowing down and possibly desertification of drylands. However, these predictions have not yet been observed in dryland vegetation due to the inherent logistic difficulty to gather longerterm in situ data. Here, we evaluate the theoretical prediction that regular vegetation patterns are associated with empirically derived temporal indicators (autocorrelation, variance, responsiveness) of critical slowing down in a dryland ecosystem in Sudan using different remote sensing products. We use recently developed methods using remote-sensing EVI time-series in combination with classified regular vegetation patterns along a rainfall gradient in Sudan to test the predicted slowing down. We tested our empirical findings against theoretical predictions from a stochastic version of a spatial explicit model that has been used to describe vegetation dynamics in drylands under aridity stress. Overall, three temporal indicators (responsiveness, temporal autocorrelation, variance) show slowing down as vegetation patterns change from gaps to labyrinths to spots towards more arid conditions, confirming predictions. However, this transition exhibits non-linearities, specifically when patterns change configuration. Model simulations reveal that the transition between patterns temporarily slows down the system affecting the temporal indicators. These transient states when vegetation patterns reorganize thus affect the systems resilience indicators in a non-linear way. Our findings suggest that spatial self-organization of dryland vegetation is associated with critical slowing down, but this transition towards reduced resilience happens in a non-linear way. Future work should aim to better understand transient dynamics in regular vegetation patterns in dryland ecosystems, because long transients make regular vegetation patterns of limited use for management in anticipating critical transitions.

International audience; Emergent insects represent a key vector through which aquatic nutrients are transferred to adjacent terrestrial food webs. Aquatic fluxes of polyunsaturated fatty acids (PUFA) from emergent insects are particularly important subsidies for terrestrial ecosystems due to high PUFA contents in several aquatic insect taxa and their physiological importance for riparian predators. While recent meta-analyses have shown the general dichotomy in fatty acid profiles between aquatic and terrestrial ecosystems, differences in fatty acid profiles between aquatic and terrestrial insects have been insufficiently explored. We examined the differences in fatty acid profiles between aquatic and terrestrial insects at a single aquatic-terrestrial interface over an entire growing season to assess the strength and temporal consistency of the dichotomy in fatty acid profiles. Non-metric multidimensional scaling clearly separated aquatic and terrestrial insects based on their fatty acid profiles regardless of season. Aquatic insects were characterized by high proportions of long-chain PUFA, such as eicosapentaenoic acid (20:5n-3), arachidonic acid (20:4n-6), and α-linolenic acid (18:3n-3); whereas terrestrial insects were characterized by high proportions of linoleic acid (18:2n-6). Our results provide detailed information on fatty acid profiles of a diversity of aquatic and terrestrial insect taxa and demonstrate that the fundamental differences in fatty acid content between aquatic and terrestrial insects persist throughout the growing season. However, the higher fatty acid dissimilarity between aquatic and terrestrial insects in spring and early summer emphasizes the importance of aquatic emergence as essential subsidies for riparian predators especially during the breading season.

International audience

The Madeira is one of the major tributaries of the Amazon River and is characterized by a large alluvial floodplain throughout the stream continuum. This study aims to better assess the hydrological functioning of the Madeira Basin over its alluvial floodplains at both local and global scales. We used the semi-distributed hydrological Soil and Water Assessment Tool (SWAT) model to simulate water discharge at a daily time step and water resources for each hydrological compartment. A new hydraulic module for water routing was implemented in the SWAT model considering the floodplain either as a simple reservoir or as a continuum where the water can flow along with the floodplain network. Both water surface estimated by L-band passive microwaves (SWAF data) and digital elevation model—shuttle radar topography mission (DEM–SRTM data) were used to delineate the floodplain, as inputs for the model. On the global scale, the amount of water stored in the Madeira floodplain is between 810 ± 230 km3 per year when the floodplains are delimited with SWAF and 1,300 ± 350 km3 per year with the DEM floodplain delineation between 2008 and 2018. Spatial altimetry (Jason 2-3) data were also applied to alluvial areas to validate the water height dynamic in floodplains at a local scale. Results show that more than 60% of the alluvial validation points display a correlation above 0.40 ± 0.02 regardless of the floodplain delineation. This study permits us to better characterize the spatio-temporal storage dynamics of the Madeira floodplains at both local and global scales, and it underlines the importance of a precise floodplain delineation, before computing biogeochemical fluxes and sediment yield.

Biogeographical studies have traditionally focused on readily visible organisms, but recent technological advances are enabling analyses of the large-scale distribution of microscopic organisms, whose biogeographical patterns have long been debated. Here we assessed the global structure of plankton geography and its relation to the biological, chemical, and physical context of the ocean (the ‘seascape’) by analyzing metagenomes of plankton communities sampled across oceans during the Tara Oceans expedition, in light of environmental data and ocean current transport. Using a consistent approach across organismal sizes that provides unprecedented resolution to measure changes in genomic composition between communities, we report a pan-ocean, size-dependent plankton biogeography overlying regional heterogeneity. We found robust evidence for a basin-scale impact of transport by ocean currents on plankton biogeography, and on a characteristic timescale of community dynamics going beyond simple seasonality or life history transitions of plankton., We thank the commitment of the following people and sponsors who made this expedition possible: CNRS (in particular Groupement de Recherche GDR3280), European Molecular Biology Laboratory (EMBL), Genoscope/CEA, Fund for Scientific Research – Flanders, VIB, Stazione Zoologica Anton Dohrn, UNIMIB, Paris Sciences et Lettres (PSL) Research University (ANR-11-IDEX-0001–02), the French Government ANR (projects FRANCE GENOMIQUE/ANR-10-INBS-09, MEMO LIFE/ANR-10-LABX-54, POSEIDON/ANR-09-BLAN-0348, PROMETHEUS/ANR-09-PCS-GENM-217, MAPPI/ANR-2010-COSI-004, TARA-GIRUS/ANR-09-PCS-GENM-218), US NSF grant DEB-1031049, FWO, BIO5, Biosphere 2, Agnès b., the Veolia Environment Foundation, Région Bretagne, World Courier, Illumina, Cap L’Orient, the EDF Foundation EDF Diversiterre, FRB, the Prince Albert II de Monaco Foundation, Etienne Bourgois, the Tara schooner and its captain and crew. We thank MERCATOR-CORIOLIS and ACRI-ST for providing daily satellite data during the expedition. The bulk of genomic computations were performed using the Airain HPC machine provided through GENCI- [TGCC/CINES/IDRIS] (grants t2011076389, t2012076389, t2013036389, t2014036389, t2015036389 and t2016036389). We are also grateful to the French Ministry of Foreign Affairs for supporting the expedition and to the countries who granted us sampling permissions.

The oases in the arid the Nefzaoua region in central-western Tunisia are associated with spring mounds. Spring mounds result from an exceptional succession of geomorphological, hydrogeological and climatic conditions and processes that follow each other in a specific order. They look like small volcanoes that range from 200 m to more than 2000 m in diameter and 3-30 m in height, which centres were once occupied by a pond fed by an artesian spring. They are at the origin of each oasis's irrigation system, which radiates from the mound's foot. Due to intense irrigation of intensive date palm plantations (Phoenix dactylifera) in recent decades, all artesian springs dried out. We established a complete inventory and typology (i.e. location, dimension, and types of degradation) of all spring mounds in the Nefzaoua region. Overall, in an area of 3000 km2, 126 spring mounds of 7 types were identified, of which 112 (89%) were degraded. Due to the low salt content in spring mound sediments, they are excavated and used as a soil amendment to expand new palm plantations. Only 14 mounds (11%) are presently preserved. Their qualification as a geomorphosite could preserve them from complete destruction.

International audience; The earthworm ecological categories defined by Marcel Bouché between 1971 and 1977 were successful and universally adopted.However, two silent shifts can be detected about their use. The first shift is that most of the authors forgot that the three maincategories (anecic, endogeic and epigeic) were indeed the three poles of a ternary plot between which all the existing speciesshould be placed. This is the reason why, intermediate categories were used by Marcel Bouché (epi-anecic, endo-anecic andendo-epigeic and intermediate, i.e. in the centre of the ternary plot). This first shift made a categorical representation out of acontinuous world and this leaded to difficulties in assigning accurately some earthworm species. The second shift is the use ofecological categories as functional groups, something Marcel Bouché never did since he never intended to describe the effectsof earthworms on their environment. The consequences of these shifts are discussed. In conclusion, we recommend to (i) readthe seminal papers (however written in French), (ii) use the intermediate ecological categories in order to better describe thecharacteristics (and their variability) of earthworm species and (iii) not use the term « functional group » for ecological categories.; Las categorías ecológicas de lombrices definidas por Marcel Bouché para las lombrices franceses entre 1971 y 1977 tuvieron unsuceso mundial y están ahora utilizadas por todos los autores de todos los continentes. Sin embargo, en la literatura científicapueden detectarse dos cambios de sentido y de uso. El primero es que la mayoría de los autores olvidaron que según MarcelBouché, las categorías anécicas, epigeas y endogeas no son 3 polos entre los cuales todas las demás especies se proyectan,razón por la que utilizaba categorías intermedias (epi-endogea, epi-anécica, endo-anécica e intermedia). Así pasamos de unavisión continua a una visión discreta, lo que plantea problemas para asignar ciertas especies de lombriz. El segundo cambio es quese utilizaron las categorías cada vez más como sinónimo de grupo funcional. Este cambio es problemático porque las categoríasdefinidas por Marcel Bouché nunca tuvieron por objeto describir los efectos de las lombrices sobre su ecosistema. Se discutenlas implicaciones de estos cambios. Por otra parte, recomendamos (i) volver a los textos originales, (ii) utilizar las categoríasintermedias (o porcentajes de pertenencia a las 3 clases principales) para describir mejor las características de las especies delombrices y (iii) no utilizar el término «grupo funcional» para hablar de las categorías ecológicas de lombrices; Les catégories écologiques de vers de terre définies par Marcel Bouché sur les vers de terre français entre 1971 et 1977 ont eu un succès mondial et sont maintenant utilisées par tous les auteurs de tous les continents. Cependant, deux glissements de sens et d’usage peuvent être décelés dans la littérature scientifique. Le premier est que la plupart des auteurs ont oublié que selon Marcel Bouché, les catégories anécique, épigée et endogée ne sont que 3 pôles entre lesquels toutes les autres espèces se projettent, raison pour laquelle il utilisait des catégories intermédiaires (épi-endogée, épi-anécique, endo-anécique et intermédiaire). On est donc passé d’une vision continue à une vision discrète, ce qui pose des problèmes pour assigner certaines espèces de vers de terre. Le second glissement est que les catégories ont de plus en plus souvent été utilisées en synonymie de groupe fonctionnel. Ce glissement est problématique car les catégories définies par Marcel Bouché n’ont jamais eu pour but de décrire les effets des vers deterre sur leur écosystème. Les implications de ces glissements sont discutées. Par ailleurs, nous recommandons (i) de revenir aux textes originels, (ii) d’utiliser les catégories intermédiaires (ou des pourcentages d’appartenance aux 3 classes principales) pour mieux décrire les caractéristiques des espèces de vers et (iii) de ne pas utiliser le terme « groupe fonctionnel » pour parler des catégories écologiques de vers.

Freshwater is a critical resource for human survival but severely threatened by anthropogenic activities and climate change. These changes strongly impact the abundance and diversity of the microbial communities which are key players in the functioning of these aquatic ecosystems. Although widely documented since the emergence of high-throughput sequencing approaches, the information on these natural microbial communities is scattered among thousands of publications and it is therefore difficult to investigate the temporal dynamics and the spatial distribution of microbial taxa within or across ecosystems. To fill this gap and in the FAIR principles context we built a manually curated and standardized microbial freshwater -omics database (FreshOmics). Based on recognized ontologies (ENVO, MIMICS, GO, ISO), FreshOmics describes 29 different types of freshwater ecosystems and uses standardized attributes to depict biological samples, sequencing protocols and article attributes for more than 2487 geographical locations across 71 countries around the world. The database contains 24,808 sequence identifiers (i.e., Run_Id / Exp_ID, mainly from SRA/DDBJ SRA/ENA, GSA and MG-RAST repositories) covering all sequence-based -omics approaches used to investigate bacteria, archaea, microbial eukaryotes, and viruses. Therefore, FreshOmics allows accurate and comprehensive analyses of microbial communities to answer questions related to their roles in freshwater ecosystems functioning and resilience, especially through meta-analysis studies. This collection also highlights different sort of errors in published works (e.g., wrong coordinates, sample type, material, spelling).

International audience; 1. Large river floodplains are dynamic environments, where alternating low and high flows are key ecological processes shaping aquatic biota. As a result of fluctuations in flow in floodplain channels, the diversity of benthic assemblages is assumed to result from the balance between surface flow connections, which are dominant during high flows, and groundwater inputs, which are dominant during low flows. However, the relative importance of these inputs in explaining aquatic invertebrate diversity has never been tested. 2. The response of aquatic invertebrates to hydrological changes of a river flood-plain was investigated in seven braided and six braided-anastomosed flood-plain channels of the French upper Rhône River that are fed by three different processes: groundwater supply (which controls the thermal inertia of the water bodies), surface slow flow connections (i.e. diffuse overbank flows; passive overflow), and surface shear stress-related connections (i.e. condensed flows; active overflow) during high flows. 3. Generalised dissimilarity models indicated that floodplain invertebrate composition had complex relationships with the three processes considered. The relative importance of the latter appeared dependent upon the morphology of the floodplain channels. In the braided channels, the effects of shear stress-related connections were more prominent than in the anastomosed ones, for which the effects of the three processes were more similar. 4. Overall, the diversity of flow connections, that is, lateral surface water connections (both shear stress-related and slow, as defined above) and vertical connection with groundwater (inferred through thermal inertia) enhanced the species turnover at the reach scale. Thermal inertia influenced invertebrate composition when, during low flow periods, surface flow connections had limited effect. 5. Our results highlighted that the role of hydrologic connectivity upon flood-plain diversity cannot be reduced to a single process. They also indicate the importance of vertical connectivity for maintaining biodiversity in floodplain habitats where surface flow connectivity is neither frequent nor constant.

Trematodes can increase intraspecific variation in the phenotype of their intermediate snail host. However, the extent of such phenotypic changes remains unclear. We investigated the influence of trematode infection on the shell morphology of Bulinus tropicus, a common host of medically important trematodes. We focused on a snail population from crater lake Kasenda (Uganda). We sampled a single homogeneous littoral habitat to minimize the influence of environmental variation on shell phenotype, and barcoded snails to document snail genotypic variation. Among the 257 adult snails analysed, 99 tested positive for trematode infection using rapid-diagnostic PCRs. Subsequently we used high-throughput amplicon sequencing to identify the trematode (co-)infections. For 86 out of the 99 positive samples trematode species delineation could discriminate among combinations of (co-)infection by 11 trematode species. To avoid confounding effects, we focused on four prevalent trematode species. We performed landmark-based geometric morphometrics to characterize shell phenotype and used regressions to examine whether shell size and shape were affected by trematode infection and the developmental stage of infection (as inferred from read counts). Snails infected by Petasiger sp. 5, Echinoparyphium sp. or Austrodiplostomum sp. 2 had larger shells than uninfected snails or than those infected by Plagiorchiida sp. Moreover, the shell shape of snails infected solely by Petasiger sp. 5 differed significantly from that of uninfected snails and snails infected with other trematodes, except from Austrodiplostomum sp. 2. Shape changes included a more protuberant apex, an inward-folded outer apertural lip and a more adapically positioned umbilicus. Size differences were more pronounced in snails with 'late' infections (>25 days) compared to earlier-stage infections. No phenotypic differences were found between snails infected by a single trematode species and those harbouring co-infections. Further work is required to assess the complex causal links between trematode infections and shell morphological alterations of snail hosts. ispartof: INTERNATIONAL JOURNAL FOR PARASITOLOGY-PARASITES AND WILDLIFE vol:18 pages:300-311 ispartof: location:England status: published

International audience

Human induced eutrophication leading to hypoxia is increasingly impacting coastal areas. Coastal upwelling systems are naturally highly productive, making it difficult to distinguish between organic matter inputs derived from natural processes and anthropogenic disturbances. This concept is newly characterised here as the “Upwelling Ecosystem Quality Paradox”. Soft-bottom macrobenthic communities have been widely used as indicators for the detection of impacts of disturbances on the biota. I evaluated the performance of several biotic indices to assess ecological conditions in a Northern Chile bay subject to natural upwelling that displays naturally shallow hypoxia and hosts an industrial hub. Results highlight limitations of commonly used indices, especially those based on pre-existing sensitivity classifications. An index that compares taxonomic abundances from study sites with selected reference stations permitted a drastic reduction in the influence of natural conditions. A new functional index is proposed that provides early detection of ecological degradation.Benthic community functioning is described along a natural depth gradient of organic matter enrichment. Filling gaps of knowledge for these benthic communities helps to support appropriate management decisions to limit adverse effects of severe hypoxia and anoxia. Long term and continuous monitoring of atmospheric, oceanographic, biogeochemical and biological processes through international collaborations of science and society appears required to reach such an aim. The conservation of upwelling ecosystems and the exceptional life they support is necessary to continue receiving the many benefits associated from these key ecosystems.; L'hypoxie produite par l’eutrophisation d’origine anthropique impacte de plus en plus sévèrement les zones côtières. Les upwellings côtiers (remontés d’eau profonde) très productifs peuvent aussi provoquer une sédimentation importante de matière organique ayant des conséquences naturelles difficiles à distinguer des perturbations anthropiques. Ce concept est décrit ici comme “le paradoxe de qualité des écosystèmes d’upwelling”. Les communautés macrobenthiques des fonds meubles sont des indicateurs propres à détecter les impacts des perturbations sur la vie marine. La performance de différents indices biotiques est évaluée pour déterminer les conditions écologiques d’une baie au nord du Chili influencée par les upwellings qui présente de l’hypoxie peu profonde et un pôle industriel important. Les résultats obtenus soulignent les limites d’indices communément utilisés, notamment ceux basés sur une classification préalable des espèces selon leur sensibilité. Un indice comparant les abondances par taxon des stations étudiées avec celles de stations de référence connues s'est avéré peu sensible aux conditions naturelles. Je propose un nouvel indice fonctionnel qui permettrait une détection précoce de la dégradation écologique. Le fonctionnement des communautés benthiques est décrit le long d’un gradient de profondeur naturellement enrichi en matière organique. Remédier aux lacunes existantes sur la connaissance de ces communautés benthiques aide aux prises de décision pour éviter les effets adverses de l’hypoxie sévère et de l’anoxie. Un monitoring pluridisciplinaire continu sur le long terme avec un lien science/société est nécessaire. La gestion et conservation des écosystèmes d’upwelling et la vie exceptionnelle qu’ils hébergent sont essentielles pour continuer à profiter des nombreux bénéfices associés à ces écosystèmes clés.

The document aims to present GLM (General Linear Model) analysis on Scientific and artisanal fisheries CPUE in order to prepare Epinephelus Aeneus (White grouper) stock assessement; Le présent document décrit l’utilisation des modèles linéaires généralisés (GLM) pour la création d’indices d’abondance du stock de Thiof (Epinephelus aeneus / White Grouper) Senegalo / Mauritanien. Les modèles GLM permettent de prendre en compte les variations de protocole d’échantillonnage dans l’observation des captures des flottilles de pêche concernées. Les données utilisées proviennent, d’une part des campagnes scientifique démersales réalisées au Sénégal depuis les années 1970, et d’autre part des données de captures et d’effort des pêcheries artisanales maritimes collectées depuis 1974 au Sénégal. French (2022-07-04)

The document will present the use of Generalized Linear Models to produce abundance indices for the stock of Pagrus Caeruleostictus in Guinea and Bissau Guinea. GLM models take into account bias of data collection and predict "unbiased values" using scientific or commercial Catch per Unit of Effort (CPUE).; Le présent document décrit l’utilisation des modèles linéaires généralisés (GLM) pour la création d’indices d’abondance du stock de Pagre (Pagrus Caeruleostictus) en Guinée et Guinée Bissau. Les modèles GLM permettent de prendre en compte les variations de protocole d’échantillonnage dans l’observation des captures des flottilles de pêche concernées. Les données utilisées proviennent, d’une part des campagnes scientifique démersales réalisées dans les deux pays depuis les années 1980, et d’autre part des données de captures et d’effort des pêcheries artisanales maritimes et industrielles disponibles pour les deux pays

Le présent document décrit l’utilisation des modèles linéaires généralisés (GLM) pour la création d’indices d’abondance du stock de Thiof (Epinephelus aeneus / White Grouper) Senegalo / Mauritanien. Les modèles GLM permettent de prendre en compte les variations de protocole d’échantillonnage dans l’observation des captures des flottilles de pêche concernées. Les données utilisées proviennent, d’une part des campagnes scientifique démersales réalisées en Mauritanie depuis les années 1980, et d’autre part des données de captures et d’effort des pêcheries artisanales maritimes collectées en Mauritanie. French (2022-07-10)

International audience

International audience; The relation between pesticides exposure and metabolic syndrome (MetS) has not been clearly identified. Performing a systematic review and meta-analysis, PubMed, Cochrane Library, Embase, and ScienceDirect were searched for studies reporting the risk of MetS following pesticides exposure and their contaminants. We included 12 studies for a total of 6789 participants, in which 1981 (29.1%) had a MetS. Overall exposure to pesticides and their contaminants increased the risk of MetS by 30% (95CI 22%–37%). Overall organochlorine increased the risk of MetS by 23% (14–32%), as well as for most types of organochlorines: hexachlorocyclohexane increased the risk by 53% (28–78%), hexachlorobenzene by 40% (0.01–80%), dichlorodiphenyldichloroethylene by 22% (9–34%), dichlorodiphenyltrichloroethane by 28% (5–50%), oxychlordane by 24% (1–47%), and transnonchlor by 35% (19–52%). Sensitivity analyses confirmed that overall exposure to pesticides and their contaminants increased the risk by 46% (35–56%) using crude data or by 19% (10–29%) using fully-adjusted model. The risk for overall pesticides and types of pesticides was also significant with crude data but only for hexachlorocyclohexane (36% risk increase, 17–55%) and transnonchlor (25% risk increase, 3–48%) with fully-adjusted models. Metaregressions demonstrated that hexachlorocyclohexane increased the risk of MetS in comparison to most other pesticides. The risk increased for more recent periods (Coefficient = 0.28, 95CI 0.20 to 0.37, by year). We demonstrated an inverse relationship with body mass index and male gender. In conclusion, pesticides exposure is a major risk factor for MetS. Besides organochlorine exposure, data are lacking for other types of pesticides. The risk increased with time, reflecting a probable increase of the use of pesticides worldwide. The inverse relationship with body mass index may signify a stockage of pesticides and contaminants in fat tissue.

Plasmids are widely involved in the dissemination of characteristics within bacterial communities. Their genomic content can be assessed by high-throughput sequencing of the whole plasmid fraction of an environment, the plasmidome. In this study, we analyzed the plasmidome of a biofilm formed in the effluents of the teaching hospital of Clermont-Ferrand (France). Our analysis discovered350 new complete plasmids, with a length ranging from 1219 to 40,193 bp. Forty-two plasmid incompatibility (Inc) groups were found among all the plasmid contigs. Ten large plasmids, described here in detail, were reconstructed from plasmid contigs, seven of which carried antibiotic resistance genes. Four plasmids potentially confer resistance to numerous families of antibiotics, including carbapenems, aminoglycosides, colistin, and chloramphenicol. Most of these plasmids were affiliated to Proteobacteria, a phylum of Gram-negative bacteria. This study therefore illustrates the composition of an environmental mixed biofilm in terms of plasmids and antibiotic resistance genes.

Field research and its methodology are at the heart of the GENgiBRe project's knowledge construction and socialisation objectives. The Methodological Guide therefore constitutes an essential outcome of our project, which reflects our "research-action" approach and our feminist epistemology. The development of this Guide was based on important instruments already proven in the field of feminism and agroecology, such as the Sociobiodiversity Map, the River of Life, the Feminist Social Cartography and the Body-Territory, which were adjusted for the objectives of our project and completed by new instruments. Through this publication, we wish to continue this collective construction, making our Methodological Guide available to communities of researchers with converging interests., La recherche sur le terrain et sa méthodologie sont au cœur des objectifs de construction et de socialisation des connaissances du projet GENgiBRe. Le guide méthodologique constitue donc un aboutissement essentiel de notre projet, qui reflète notre approche "recherche-action" et notre épistémologie féministe. L'élaboration de ce guide est basée sur des instruments importants déjà éprouvés dans le domaine du féminisme et de l'agroécologie, tels que la carte de la sociobiodiversité, le fleuve de la vie, la cartographie sociale féministe et le corps-territoire, qui ont été adaptés aux objectifs de notre projet et complétés par de nouveaux instruments. A travers cette publication, nous souhaitons poursuivre cette construction collective, en mettant notre Guide méthodologique à la disposition de communautés de chercheur-e-s aux intérêts convergents., A pesquisa de campo e sua metodologia estão no centro dos objetivos de construção e socialização do conhecimento do projeto GENgiBRe. O Guia metodológico, portanto, constitui um resultado essencial do nosso projeto, que reflete nossa abordagem de “pesquisação” e nossa epistemologia feminista. O desenvolvimento deste Guia foi baseado em instrumentos importantes já provados no campo do feminismo e da agroecologia, como o Mapa da Sociobiodiversidade, o Rio da Vida, a Cartografia Social Feminista e o Corpo-Território, que foram ajustados para os objetivos do nosso projeto e completados por novos instrumentos. Através desta publicação, desejamos continuar esta construção coletiva, disponibilizando nosso Guia Metodológico para comunidades de pesquisadoras e pesquisadores com interesses convergentes.

The blue Planet is also a Green World, with tropical islands known for their exceptional but vulnerable biodiversity (e.g. facing the threats of habitat transformation, biological invasions, climate change, ...). Listed as a UNESCO World Heritage Site (40% of its area), belonging to a global biodiversity hotspot, Reunion Island is no exception to these issues for conservation of its native and endemic species. Massively planting native species in restoration and revegetation is a mean for recovering biodiversity. However, this political and societal will come up against several scientific and technical obstacles for seed collection, storage, germination, seedling emergence and planting. In addition, little is known in seed ecology, the scientific field which is associated with these obstacles. By crossing scientific and technical issues, this thesis aims to contribute to the seed morpho-physiological characterization of native and endemic species along vegetation zones of an oceanic island with a strong altitudinal gradient.In two types of lowland forests, the chapter 1 studies the morphological characteristics and seed germination on Mimusops balata. The species is present in both dry forest and lowland rainforest. We observed a morphological variation in fruits and seeds depending on collection site and year, with a probably strong influence of climatic factors. At the species level, M. balata have recalcitrant seeds with no dormancy.In rainforest, tropical montane cloud forests and subalpine vegetation, the chapters 2 studies the same type of characterization on a native liana in Reunion Island, Clematis mauritiana. There are no distinctive morphological groups for forest and subalpine environments. But, some seed morphological and physiological characteristics in subalpine vegetation raise the question of the existence of phenotypic plasticity or a morphotype. At the species level, C. mauritiana have dormant seeds with at least a morphological component.In subalpine vegetation, the chapter 3 focuses on dormancy and photoblasty detection of five emblematic species. One species has no dormant seeds contrary to the four others, with potentially a physiological dormancy. Two species require light for seed germination. Gibberellic acid substitutes for light but not Smoke Water, except for a species for specific conditions.Overall, these studies notice a still too great lack of knowledge about seed storage behavior, and more largely in seed ecology. For planting programs, these data permit to design a tool with scientific and technical data for ENDEMIEL project. This initiative aims to plant 61,000 native or endemic trees/shrubs along an altitudinal gradient (36 km – ranging from 400 to 1600 m a.s.l, crossing different habitats). These Research works highlight also the necessary to complete data about seed morphology and maturity. This leads us to propose to design a numerical fruit and seed collection/library with a database of morphological measurement.Using native plants is good, but using them properly is better!; La Terre est une planète bleue mais c’est aussi un monde vert abritant des îles tropicales reconnues pour leur biodiversité exceptionnelle mais vulnérable (e.g. face aux menaces de transformation des habitats, des invasions biologiques, du changement climatique, …). Appartenant à un hotspot mondial de la biodiversité, La Réunion n’échappe pas aux problématiques de sauvegarde de ses espèces indigènes et endémiques, notamment avec 40% de sa surface inscrite au Patrimoine mondial de l’UNESCO. Planter massivement des espèces indigènes en restauration écologique et en revégétalisation devient ainsi un moyen pour reconquérir la biodiversité réunionnaise. Toutefois, cette volonté politique et sociétale se heurte à plusieurs verrous scientifiques et techniques tels que comment récolter, stocker, faire germer, obtenir des plants et planter ces espèces. Par ailleurs, sur le plan académique, peu de données sont disponibles sur les champs scientifiques associés à ces problématiques. En croisant les enjeux scientifiques et techniques, ce travail de thèse vise à contribuer à la caractérisation morpho-physiologique de semences d’espèces indigènes et endémiques le long de l’étagement de végétation d’une île océanique à fort gradient altitudinal.Au sein de deux forêts de basse altitude, le chapitre 1 porte sur les caractéristiques morphologiques et la germination des graines de Mimusops balata, présente à la fois dans la forêt sèche et dans la forêt tropicale humide de basse altitude. Une variation morphologique des fruits et graines est observée en fonction des sites et de l’année de récolte, avec une influence probablement forte des conditions climatiques. Au niveau de l’espèce, M. balata présente des graines récalcitrantes sans dormance.Au sein de la forêt tropicale humide de moyenne altitude, de montagne et la végétation subalpine, le chapitre 2 traite cette même caractérisation sur une liane indigène de La Réunion, Clematis mauritiana. Il n’y a pas de groupes morphologiques discriminants entre le milieu forestier et subalpin. Mais certaines caractéristiques morphologiques et physiologiques des graines de la végétation subalpine posent la question de l’existence d’une forme de plasticité phénotypique ou de l’existence potentiel d’un morphotype. Au niveau de l’espèce, une dormance avec au moins une composante morphologique est détectée.Au sein de la végétation subalpine, le chapitre 3 se focalise sur la détection de dormance et de la photosensibilité de cinq espèces emblématiques de l’étage. Une espèce ne présente pas de dormance contrairement aux quatre autres, avec potentiellement une composante physiologique. Deux espèces ont des graines à photosensibilité positive. L’acide gibbérellique peut se substituer à la lumière mais pas l’eau fumée, sauf pour une espèce dans certaines conditions.Globalement, ces travaux relèvent notamment un manque de connaissances encore trop important sur le comportement à la conservation des semences, et plus largement en écologie des semences. En termes de transferts de connaissances, ces données ont permis concrètement d’élaborer une partie des itinéraires techniques de production destinés au projet ENDEMIEL ambitionnant de planter plus de 61 000 arbres/arbustes indigènes et endémiques le long d’un gradient altitudinal de 36 km allant de 400 à 1600 mètres et traversant plusieurs étages de végétation. Ces travaux soulignent également l’importance de compléter les données de caractérisation morphologique et de maturité des semences, amenant à la proposition de mettre en place une carpo-séminothèque numérique contenant une base de données morphométriques.Vouloir utiliser des plantes indigènes, c’est bien mais bien le faire c’est mieux !

Human activities are affecting ocean health dramatically. Climate change caused by anthropogenic greenhouse gas emission results in sea-surface warming, polar ice caps melting, ocean acidification, and changes in circulation and mixing regimes leading to stratification. All life forms in the ocean are impacted, primarily microorganisms which dominate ocean biodiversity and play a major role in global ecosystem function. Microbial communities have a capacity for rapid adaptation because of their large population sizes and short generation times, potentially altering the global cycles of carbon and nutrients in response to climate change, but these feedbacks are largely unresolved. In this thesis, we focus on heterotrophic bacteria and their ability to remineralize dissolved organic matter into inorganic nutrients. This `microbial loop' fuels a carbon recycling pathway, but its response to climate change is still poorly understood. Through eco-evolutionary modeling, we resolve the potential feedback loop resulting from bacterial adaptation in different oceanic regions, both at the surface and deep in the water column. We find that bacterial adaptation tends to mitigate the negative effect climate change has on dissolved organic matter regeneration, with varying degrees depending on the biogeographical region. In order to generate predictions of our model at the global scale, we develop a novel framework for integrating eco-evolutionary processes with Earth system models. We find that bacterial adaptation in the microbial loop adds uncertainty to global ocean ecosystem forecasts, and call for further eco-evolutionary studies at this scale. Finally, we extend our eco-evolutionary modeling framework to address the effect of bacteriophages – arguably a major demographic factor of bacterial populations. We present preliminary analyses of bacteriophages’ influence on the carbon cycle and how they may alter the speed and dynamics of bacterial adaptation to changing environments. Overall, this thesis emphasizes two current `blind spots' of Earth system models: an explicit representation of the microbial loop and the integration of eco-evolutionary processes that are mediated by ocean microorganisms., Les activités humaines ont un impact considérable sur la santé des océans. Le changement climatique causé par les émissions anthropiques de gaz à effet de serre entraîne un réchauffement de la surface de la mer, la fonte des calottes polaires, l'acidification des océans et des changements dans les régimes de circulation et de mélange conduisant à une stratification de la colonne d'eau. Toutes les formes de vie dans l'océan sont touchées, principalement les micro-organismes qui dominent la biodiversité des océans et jouent un rôle majeur dans la fonction des écosystèmes marins. Les communautés microbiennes ont une capacité d'adaptation rapide en raison de la taille importante de leurs populations et de la brièveté de leur temps de génération, ce qui peut potentiellement modifier les cycles globaux du carbone et des nutriments en réponse au changement climatique, mais ces rétroactions sont encore peu comprises. Dans cette thèse, nous nous concentrons sur les bactéries hétérotrophes et leur capacité à reminéraliser la matière organique dissoute en nutriments inorganiques. Cette "boucle microbienne" alimente une voie de recyclage du carbone, mais sa réponse au changement climatique est encore mal déterminée. Grâce à une modélisation éco-évolutive, nous quantifions la boucle de rétroaction potentielle résultant de l'adaptation bactérienne dans différentes régions océaniques, tant à la surface qu'en profondeur dans la colonne d'eau. Nous constatons que l'adaptation bactérienne tend à atténuer l'effet négatif du changement climatique sur la régénération de la matière organique dissoute, avec des degrés variables selon la région biogéographique. Afin de tester les prédictions de notre modèle dans un contexte global, nous développons un nouveau cadre pour intégrer les processus éco-évolutifs aux modèles de circulation océanique. Nous constatons que l'adaptation bactérienne dans la boucle microbienne peut ajouter de l'incertitude à nos prévisions, et appelons à de nouvelles études éco-évolutives à cette échelle. Enfin, nous incluons les bactériophages dans notre modèle et étudions à la fois leur influence biogéochimique sur le cycle du carbone et la façon dont ils pourraient influencer la vitesse d'adaptation des bactéries aux environnements changeants. Dans son ensemble, cette thèse met l'accent sur deux "angles morts" actuels des modèles du système terrestre : une représentation explicite de la boucle microbienne et l'intégration des processus éco-évolutifs dans l’analyse de sa dynamique en réponse aux changements globaux.

Increasing evidence indicates that sexual coercion is widespread. While some coercive strategies are conspicuous, such as forced copulation or sexual harassment, less is known about the ecology and evolution of intimidation, where repeated male aggression promotes future rather than immediate mating success with targeted females. Although known in humans, intimidation was recently reported in chimpanzees (Pan troglodytes) and chacma baboons (Papio ursinus), where males are regularly violent against females. Here, we investigate the nature of male coercive strategies in wild mandrills (Mandrillus sphinx), a primate living in large polygynandrous groups where severe male aggression towards females is rare and females can form coalitions against males. Yet, we found support for all three predictions of the sexual coercion hypothesis, namely that male aggression (1) specifically targets sexually receptive females, (2) inflicts costs to these females, and (3) increases male mating success in the long-term. These results hold true when considering only non-physical threats, or only severe aggression. Finally, we show that high-ranking females are most targeted by males, probably because of their higher reproductive performances, while high-ranking males are most coercive. These results indicate that sexual intimidation is widespread in sexually dimorphic and group-living mammals, and that males and females vary in their propensities to use, and to be exposed to sexual coercion, respectively.

The crucial role of crustose coralline algae (CCA) in inducing hard coral larval settlement and ensuring the replenishment of coral reefs is widely accepted, and so are the negative effects of anthropogenic CO2 emissions on both CCA abundance and coral development. However, diversified and well-developed coral reef communities have been recently discovered in natural conditions where CCA and corals would not be expected to thrive. Back-reef pools, volcanic CO2 vents, mangrove estuaries, and semi-enclosed lagoons systems can present seawater pH, temperature, and dissolved oxygen values reaching or even exceeding the conditions currently predicted by the Inter Panel on Climate Change (IPCC) for 2100. In the semi-enclosed lagoon of Bouraké (New Caledonia, southwest Pacific Ocean), seawater pHT, dissolved oxygen, and temperatures regularly fluctuate with the tide reaching respectively minimum values of 7.23 pHT units, 2.28 mg O2 L-1, and maximum of 33.85°C. This study reports the effect of such extreme environmental conditions on hard coral recruitment and CCA originally settled at a forereef on artificial substrates that were transplanted over two years in two fringing reef and at the Bouraké lagoon. Our data emphasize the negative effects of the extreme conditions in our study sites on the CCA, which decreased in cover by ca. 80% and lost in the competition with turf algae, which, in turn, increased up to 162% at the end of the two years. Conversely, hard coral recruitment remained high at Bouraké throughout the study, three-fold higher than at two sites located outside Bouraké where environmental conditions were typical for coastal fringing reefs. Our findings show that while such extreme, climate change like-conditions have a direct and adverse effect on CCA abundance, and despite a certain persistence, coral larvae settlement was not affected. Based on previous findings from Bouraké, and the present observations, both coral recruits and adults seem to be unaffected despite the extreme environmental conditions. This study supports previous research illustrating how extreme natural and variable environments may reveal unexpected and positive insights on the processes underlying coral acclimatization and adaptation to global change.

International audience

International audience; A free and easily accessible web application ; R package for local installation ; Use of phyloseq object (output from rANOMALY, FROGS) ; Interactive filters, to focus on a specific group of samples. Complete diversity analysis with advanced visualizations and statistical tests, differential analysis and more features. Metabarcoding is widely used for community composition studies of complex samples (food, gut, environement) ; Existing tools for the analysis of these data needs some coding knowledge. We present a Shiny application for metabarcoding data with interactive features allowing user to explore and analyse them.

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