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Let $S=\{p_1, \dots, p_r,\infty\}$ for prime integers $p_1, \dots, p_r.$ Let $X$ be an $S$-adic compact nilmanifold, equipped with the unique translation invariant probability measure $\mu.$ We characterize the countable groups $\Gamma$ of automorphisms of $X$ for which the Koopman representation $\kappa$ on $L^2(X,\mu)$ has a spectral gap. More specifically, we show that $\kappa$ does not have a spectral gap if and only if there exists a non-trivial $\Gamma$-invariant quotient solenoid (that is, a finite-dimensional, connected, compact abelian group) on which $\Gamma$ acts as a virtually abelian group., Comment: 25 pages

Background The aim of this study was to review, systematically, evidence concerning the link between the ACTN3 R577X polymorphism and the rates and severity of non-contact injuries and exercise-induced muscle damage in athletes and individuals enrolled in exercise training programs. Methods A computerized literature search was performed in the electronic databases PubMed, Web of Science, and SPORTDiscus, from inception until November 2020. All included studies compared the epidemiological characteristics of non-contact injury between the different genotypes of the ACTN3 R577X polymorphism. Results Our search identified 492 records. After the screening of titles, abstracts, and full texts, 13 studies examining the association between the ACTN3 genotypes and the rate and severity of non-contact injury were included in the analysis. These studies were performed in 6 different countries (Spain, Japan, Brazil, China, Republic of Korea, and Italy) and involved a total participant pool of 1093 participants. Of the studies, 2 studies involved only women, 5 studies involved only men, and 6 studies involved both men and women. All the studies included were classified as high-quality studies (≥6 points in the Physiotherapy Evidence Database (PEDro) scale score). Overall, evidence suggests there is an association between the ACTN3 R577X genotype and non-contact injury in 12 investigations. Six studies observed a significant association between ACTN3 R577X polymorphism and exercise induced muscle damage: two with non-contact ankle injury, three with non-contact muscle injury, and one with overall non-contact injury. Conclusion The present findings support the premise that possessing the ACTN3 XX genotype may predispose athletes to a higher probability of some non-contact injuries, such as muscle injury, ankle sprains, and higher levels of exercise-induced muscle damage.

International audience; In the sub-Antarctic region, climate change is particularly rapid, while their freshwater ecosystems, such as ponds, host plant species with limited spatial distributions. These particular systems and their plant communities remain however poorly known and the context of their changing habitat calls for deeper insights into these systems. We performed an extensive survey of 45 ponds over three locations of the Iles Kerguelen during the winter and summer seasons of two years, which included the measurement of 12 abiotic parameters and the assessment of the plant community composition. Overall, our results showed that Iles Kerguelen ponds are shallow freshwater ecosystems harbouring species-poor plant communities with high even- ness, of which structure did not vary among the sampled locations. Three different habitats were identified among ponds in relation with nutrient supply by marine animals, which ultimately influenced plant community structure and cover. We highlight that these habitats are mostly determined by water depth, nutrients, and temperature (mean and variance). Present plant community composition was more strongly correlated with plant community composition in the previous year than with abiotic conditions. Overall, this study provides new knowledge on the aquatic plant communities and the functioning of Iles Kerguelen freshwater ecosystems, which can serve as a basis for future studies dealing with the impact of climate change in the sub-Antarctic region.

We study its controllability around the ground state when the linearized system is not controllable and wonder whether the quadratic term can help to recover the directions lost at the first order. More precisely, in this paper, we formulate assumptions under which the quadratic term induces a drift which prevents the small-time local controllability (STLC) of the system in appropriate spaces. For finite-dimensional systems, quadratic terms induce coercive drifts in the dynamic, quantified by integer negative Sobolev norms, along explicit Lie brackets which prevent STLC.In the context of the bilinear Schr{\"o}dinger equation, the first drift, quantified by the $H^{-1}$-norm of the control, was already observed and used to deny STLC with controls small in $L^\infty$. In this article, we improve this result by denying STLC with controls small in $W^{-1, \infty}$. Furthermore, for any positive integer $n$, we formulate assumptions under which one may observe a quadratic drift quantified by the $H^{-n}$-norm of the control and we use it to deny STLC in suitable spaces.

International audience; Context : Flower-visiting insects depend on floral resource availability from both cultivated and semi-natural habitats in agricultural landscapes. Landscape studies exploring insect abundance mainly focus on land cover maps without considering plant species within. Highlighting the functional role of landscapes through the potential floral resources they provide is an overlooked innovative approach. Objectives : We aimed to identify traits of floral communities that are important, across several spatial scales, for explaining the abundance of flower-visiting insects. Mapping and quantifying potential floral resources according to their attractivity, accessibility and profitability in both crop and non-crop habitats was performed to gain insights into flower-vising insect requirements. Methods : We translated land-cover maps of 39 landscapes of 250 m, 500 m and 1000 m radius into potential floral resource maps, using pre-existing vegetation surveys and floral traits databases. In the centres of the landscapes, the abundance of flower-visiting insect groups (domestic and wild bees, bumblebees and hoverflies) were recorded in organic winter cereal fields. We then fitted Generalized Linear Models (GLMs) to investigate the effects of flower trait variables (pre-selected with conditional random forests) at both field and landscape scales on the abundance of each flower-visiting insect group. Results : Floral resource maps explained the abundances of flower-visiting insect groups. Small wild bees (< 1 cm) responded positively to the relative amount of attractive and accessible floral resources at 250 m. The abundance of domestic bees and bumblebees was positively correlated with the relative amount of high nectar producing plants at 1000 m. The abundance of hoverflies was positively influenced by the relative amount of actinomorphic flowers (i.e., those with radial symmetry), at 1000 m.Conclusion : Resource maps could explain flower-visiting insect abundances, identify which category of floral resources organisms require, and determine in which habitat types these resources prevail. These results open a new research area related to managing the environment by optimising floral resources for flower-visiting insect conservation and pollination maintenance.

International audience; Bilebullephlebia legendrei n. gen., n. sp. is described, illustrated, and placed into the small epiproctophoran family Burmaphlebiidae. This family was previously known from the mid-Cretaceous Kachin amber by two monotypic genera, but the new fossil shows that its diversity is underestimated. At least one additional genus with an enigmatic wing venation remains to be described from the same deposit. Nothing is known about the genitalia configuration of the Burmaphlebiidae but new fossils are expected to clarify the position of the family which is currently only discussed in light of wing venation characters.

The transition from a greenhouse to an icehouse world at the Eocene-Oligocene Transition (EOT) coincided with a large decrease of pollen from the steppe-adapted genus Nitraria. This genus, now common along the Mediterranean coast, Asia and Australia, has a proposed coastal origin and a geographically widespread fossil record. Here we investigated the evolution, taxonomic diversity and morphological disparity of Nitraria throughout the Cenozoic by integrating extant taxa and fossil palynological morphotypes into a unified phylogenetic framework based on both DNA sequences and pollen morphological data. We present the oldest fossil pollen grain of Nitraria, at least 53 Myr old. This fossil was found in Central Asian deposits, providing new evidence for its origin in this area. We found that the EOT is an evolutionary bottleneck for Nitraria, coinciding with retreat of the proto-Paratethys Sea, a major global cooling event and a turnover in Central Asian steppe vegetation. We infer the crown age of modern Nitraria spp. to be significantly younger (Miocene) than previously estimated (Palaeocene). The diversity trajectory of Nitraria inferred from extant-only taxa differs markedly from one that also considers extinct taxa. Our study demonstrates it is therefore critical to apply an integrative approach to fully understand the plant evolutionary history of Nitrariaceae.

International audience; The structural organization of heterogeneous and multiphase natural aggregates depends on the biophysicochemical conditions prevailing in the environment, with major ions playing a crucial role. In this study, the impact of aluminum (Al) on iron-organic matter (Fe-OM) aggregates was investigated since Al can interact with OM and can be incorporated in Fe-oxyhydroxides or adsorbed on their surface. Mimetic environmental Fe-OM-Al aggregates were synthesized at various [Fe] and [Al] with a constant [OM]. At low [Al+Fe], Fe-OM-Al aggregates exhibit a colloidal behavior. Within the aggregates, Fe is present as Fe(III)-oligomers and ferrihydrite-like nanoparticles whereas Al forms monomers, oligomers and small polymers, all bound to OM. The Al and Fe phases interacted with each other. At high [Fe+Al], the Fe(III)-oligomers and Al monomers/oligomers polymerized which increases the size and quantity of the ferrihydrite-like nanoparticles and Al polymers and then branched out the OM, resulting in a large settling network. The effect of Al on the Fe-OM aggregates structure could also have an impact on the fate of pollutants. The occurrence of Al amorphous hydroxides and the increase in ferrihydrite-like nanoparticles lead to a higher availability of surface reactive sites and subsequently to an increase in the sorption capacity of the Fe-OM aggregates for pollutants that exhibit a greater affinity for minerals than for organics.

Variation in species richness across the tree of life, accompanied by the incredible variety of ecological and morphological characteristics found in nature, has inspired many studies to link traits with species diversification. Angiosperms are a highly diverse group that has fundamentally shaped life on earth since the Cretaceous, and illustrate how species diversification affects ecosystem functioning. Numerous traits and processes have been linked to differences in species richness within this group, but we know little about how these interact and their relative importance. Here, we synthesized data from 152 studies that used state-dependent speciation and extinction (SSE) models on angiosperm clades. Intrinsic traits related to reproduction and morphology were often linked to diversification but a set of universal drivers did not emerge as traits did not have consistent effects across clades. Importantly, dataset properties were correlated to SSE model results - trees that were larger, older, or less well-sampled tended to yield trait-dependent outcomes. We compared these properties to recommendations for SSE model use and provide a set of best practices to follow when designing studies and reporting results. Finally, we argue that SSE model inferences should be considered in a larger context incorporating species’ ecology, demography and genetics.

Hybridization and polyploidy are key evolutionary forces in plant diversification, and their co-occurrence in the context of allopolyploid speciation is often associated with increased ability to colonize new environments and invasiveness. In the genus Ulex (Fabaceae), the European gorse (Ulex europaeus subsp. europaeus) is the only invasive and the only polyploid that has recently spread in different eco-geographical regions across the world. Understanding what confers such ecological advantages to this species, compared to its diploid and polyploid congeners, first requires clarification of the ecogeographical and evolutionary context of its formation. To achieve this, the geographical distributions of all Ulex spp. were estimated from species occurrence records, and phylogenetic analyses including all Ulex spp. were performed based on four nuclear (ITS and ETS nrDNA) and plastid (rps12 intron and trnK-matK) regions. The resulting trees were dated using a secondary calibration. Patterns of DNA sequence variation and dated phylogenetic trees were then interpreted in light of previous knowledge of chromosome numbers in Ulex to infer past events of polyploid speciation in the genus. We show that: (1) most current Ulex spp. radiated in the Iberian Peninsula during the past 1–2 Myr; (2) the history of Ulex was punctuated by multiple whole-genome duplication events; and (3) U. europaeus subsp. europaeus is the only gorse taxon that was formed by hybridization of two well-differentiated lineages (which separated c. 5 Mya) with wide climatic ranges (currently represented by Ulex minor and Ulex europaeus subsp. latebracteatus), possibly contributing to the invasive nature and wider climatic range of U. europaeus subsp. europaeus. These findings provide a much-needed evolutionary framework in which to explore the adaptive consequences of genome mergers and duplication in Ulex.

International audience; Despite the wide availability of large motion databases, and recent advances in exploiting them to create tailored contents, artists still spend tremendous efforts in editing and adapting existing character animations to new contexts. This motion editing problem is a well-addressed research topic. Yet only a few approaches have considered the influence of the camera angle, and the resulting visual features it yields, as a mean to control and warp a character animation. This paper proposes the design of viewpoint-dependent motion warping units that perform subtle updates on animations through the specification of visual motion features such as visibility, or spatial extent. We express the problem as a specific case of visual servoing, where the warping of a given character motion is regulated by a number of visual features to enforce. Results demonstrate the relevance of the approach for different motion editing tasks and its potential to empower virtual characters with attention-aware communication abilities.

A research to study the zooplanktonic population in relation to some abiotic variables of the Kribian coast waters was conducted from July to December 2020 following a monthly sampling in six (6) selected sites. The physicochemical parameters were determining out using standard methods. Concerning the zooplankton, the water was collected at the surface, in the trophogenic and tropholytic layers, then filtered through a 64 µm plankton sieve and the retentate was fixed with 96% alcohol. Identification and counting were done in the laboratory using a Wild M5 binocular loupe, appropriate keys and works. The physicochemical results showed a very good oxygenation of the waters (91.85 ± 3.87%), basic pH (8.43 ± 0.54 U.C), a low salinity and conductivity of respectively 13.04 ± 3.92 g/L and 23.07±4.23 µS/cm characteristic of the haline domains and a temperature of 28.66 ± 1.35°C. With regard to nutrients, the values recorded showed a progressive enrichment of the water in nitrate (2.2±1.81mg/L) and a low concentration in orthophosphate (0.25±0.41mg/L). the zooplankton community haboured, 54 taxa belonging to 3 major groups (Copepoda, Cladocera, Ciliate) and other Zooplankton, 24 families and 29 genera were recorded. The Copepod group dominated the taxonomic richness with 34 taxa (62.96% of total richness), followed by Tintinidae with 4 taxa (7.4%), Cladocera with 1 marine taxa (1.9%) and 15 taxa for other zooplankton (27.8%). Quantitatively, Copepods were once again the most abundant group in the population, with an average of 78.3% of the total zooplankton abundance. The dominant copepod taxa in terms of abundance were those of the families of: Paracalanidae (mean abundance: 116 ind/L) and Oithonidae (mean abundance: 99ind/L).

International audience; Plastic has been largely detected in estuarine environments and represents major concern towards aquatic living organisms. The present study evaluates the impact of microplastics (MPs) and nanoplastics (NPs) under realistic exposure conditions. Scrobicularia plana individuals were exposed to low concentrations (0.008, 10, and 100 µg L−1) of environmental MPs and NPs as well as to standard PS NPs, as a comparison condition. The aim of this study was to understand the ecotoxicological effects of environmental plastic particles on S. plana gills and digestive glands but also to compare the effects of plastic polymers size in order to highlight if the size could induce different toxicity profiles within this model organism, at different levels of biological organization. Results showed a differential induction of detoxification enzymes (CAT, GST), immunity (AcP), DNA damage processes as well as a differential effect on behavior and condition index of animals depending upon the type of plastic, the size, the concentration tested, and the type of organ. This study underlines the necessity of testing (i) plastics collected from the environment as compared to standard ones and (ii) the effect of size using plastics coming from the same batch of macrosized plastics. This study concludes on the future need directions that plastic-based studies must take in order to be able to generate a large quantity of relevant data that could be used for future regulatory needs on the use of plastic.

International audience; Wetlands are the largest natural source of methane (CH4) to the atmosphere. The eddy covariance method provides robust measurements of net ecosystem exchange of CH4, but interpreting its spatiotemporal variations is challenging due to the co-occurrence of CH4 production, oxidation, and transport dynamics. Here, we estimate these three processes using a data-model fusion approach across 25 wetlands in temperate, boreal, and Arctic regions. Our data-constrained model—iPEACE—reasonably reproduced CH4 emissions at 19 of the 25 sites with normalized root mean square error of 0.59, correlation coefficient of 0.82, and normalized standard deviation of 0.87. Among the three processes, CH4 production appeared to be the most important process, followed by oxidation in explaining inter-site variations in CH4 emissions. Based on a sensitivity analysis, CH4 emissions were generally more sensitive to decreased water table than to increased gross primary productivity or soil temperature. For periods with leaf area index (LAI) of ≥20% of its annual peak, plant-mediated transport appeared to be the major pathway for CH4 transport. Contributions from ebullition and diffusion were relatively high during low LAI (

International audience; The objective of the paper is to better understand and quantify the flow structure in fractured rocks from flow logs, and to propose relevant indicators for validating, calibrating or even rejecting hydrogeological models. We first studied what the inflow distribution tells us about the permeability structure from a series of analyses: distribution of transmissivities as a function of depth, proportion of flowing sections as a function of section scale, and scaling of the arithmetically-averaged and geometrically-averaged permeability. We then define three indicators that describe few fundamental characteristics of the flow/permeability, whatever the scale: a percolation scale , the way permeability increases with scale above , and the variability of permeability. A 4th indicator on the representative elemental volume could in principle be defined but the data show that this volume/scale is beyond the 300 m investigated. We tested a series of numerical models built in three steps: the geo-DFN based on the observed fracture network, the open-DFN which is the part of the geo-DFN where fractures are open, and a transmissivity model applying on each fracture of the open-DFN (Discrete Fracture Network). The analysis of the models showed that the percolation scale is controlled by the open-DFN structure and that the percolation scale can be predicted from a scale analysis of the percolation parameter (basically, the third moment of the fracture size distribution that provides a measure of the network connectivity). The way permeability increases with scale above the percolation threshold is controlled by the transmissivity model and in particular by the dependence of the fracture transmissivity on either the orientation of the fractures via a stress-controlled transmissivity or their size or both. The comparison with data on the first two indicators shows that a model that matches the characteristics of the geo-DFN with an open fraction of 15% as measured adequately fits the data provided that the large fractures remain open and that the fracture transmissivity model is well selected. Most of the other models show unacceptable differences with data but other models or model combinations has still to be explored before rejecting them. The third indicator on model variability is still problematic since the natural data show a higher variability than the models but the open fraction is also much more variable in the data than in the models.

We characterize geometrically the regularizing effects of the semigroups generated by accretive non-selfadjoint quadratic differential operators. As a byproduct, we establish the subelliptic estimates enjoyed by these operators, being expected to be optimal. These results prove conjectures by M. Hitrik, K. Pravda-Starov and J. Viola. The proof relies on a new representation of the polar decomposition of these semigroups. In particular, we identify the selfadjoint part as the evolution operator generated by the Weyl quantization of a time-dependent real-valued nonnegative quadratic form for which we prove a sharp anisotropic lower bound., Comment: arXiv admin note: text overlap with arXiv:1510.01992, arXiv:1703.02797 by other authors

International audience; The relative contributions of agricultural intensity and semi-natural habitats to the multifunctionality and sustainability of ecosystems at different spatial scales remain largely under-investigated. In this study, we assessed the multifunctionality of 40 winter cereal fields and 40 hedgerows based on ecological, agronomic and socio-economic performance using data from field surveys and interviews with farmers. We specifically focused on the effects of local farming systems (organic vs. conventional) and management (cereals intercropped with legumes vs. monocrops), the effects of landscape heterogeneity related to hedgerow density, and the spatial extent of semi-natural habitat and organic farming. Multifunctionality indices associated with increased values of proxies for biodiversity conservation and pest control functions were higher for hedgerows than crop fields. Agroecosystem multifunctionality was similar between organic and conventional farming as a consequence of antagonistic responses of individual function proxies. While organic farming promoted the ecological performance of crops, conventional farming resulted in higher agronomic performance (i.e. yield). Interestingly, lower yields of organic crops were not systematically associated with reductions in socio-economic performance in terms of farmer income and labour. At the landscape scale, hedgerow density and the extent of semi-natural habitats and organic farming had little influence on agroecosystem multifunctionality or individual function proxies. Synthesis and applications. Our results confirm the high value of hedgerows and organic farming at the local scale for the ecological performance of ecosystems. Our study suggests that, among existing agri-environment schemes in Europe, hedgerow planting and organic farming are appropriate tools to optimise the ecological performance of ecosystems at the local scale even if antagonistic effects with agronomic performance should not be neglected.

International audience; Small shallow lakes (SSLs) have great conservation value and support numerous ecosystem services. However, these small ecosystems are faced with many threats, including eutrophication, which tends to shift biodiverse SSLs to a turbid state dominated by phytoplankton. The ecological quality of SSLs still remains poorly evaluated because of the lack of adapted tools. We propose a new trophic index-TIM2S-based on the tolerance range of 245 macrophyte species to total phosphorus. As a single trophic index can favour oligotrophic ecosystems and their associated species to the detriment of more eutrophic but rare species, we converted TIM2S into a predictive reference-based model. Then, we compared TIM2S with five existing trophic indices in their efficiency to discriminate trophic levels and disentangle eight anthropogenic or internal pressures. TIM2S was the only index strongly correlated with total phosphorus and able to discriminate trophic levels. Most existing trophic indices are expert-based, and reflect community alteration rather than eutrophication. These expert-based indices are also dependent on numerous environmental factors, highlighting the need for robust predictive models to evaluate ecological statuses accurately. TIM2S is Water Framework Directive-compatible and can be used widely in Europe to evaluate the trophic status and trophic alterations of SSLs.

International audience; Nectar is a key resource for numerous insects. Despite its importance, nectar productivity has mainly been assessed using one sampling method, in which the volume of nectar produced by a flower is measured after 24 h of isolation from insects (‘measured 24 h volume’ hereafter). This method assumes that nectar removal by flower-visiting insects does not affect nectar productivity. Hence, a linearity in the nectar production dynamic is assumed. The effect of nectar removal could lead to an actual volume of nectar produced per flower over 24 h being higher or lower than the measured 24 h volume. Whether the nectar productivity is influenced by insect activity still therefore needs to be assessed. In a field experiment, we estimated the nectar production dynamics of lavender (Lavandula hybrida) and fennel (Foeniculum vulgare) flowers and tested whether they met the linearity assumption. Then, we developed a simulation model to identify how different scenarios of insect foraging activity: nectar removal rate (average and maximum), and flower-selection strategies (random selection or rewarding flower selection) alter the estimated 24 h volume of nectar for both crops (‘estimated 24 h volume’ hereafter). Finally, we tested whether the estimated 24 h volume differed from the measured 24 h volume for both crops. Lavender and fennel showed equal measured 24 h volume of nectar but the produced nectar volume over 6 h suggested that a flower of lavender was more productive than a flower of fennel. Both nectar production dynamics did not meet the assumption of linearity. The simulation models showed that the estimated 24 h volume increased with maximum nectar removal rate for lavender, and the opposite was found for fennel. Rewarding selection always increased the estimated 24 h volume for fennel while for lavender a positive effect was detected at average rate of nectar removal. We found that the estimated 24 h volume was always greater than the measured 24 h volume. Our model demonstrated that the effect of insect foraging activity on flower's nectar productivity should be considered while estimating the resources produced by plants. As an alternative, measures of produced nectar volume in short time spans may be compared with the measured 24 h volume to check the reliability of this widespread method.

In this work, we adapt the {\em micro-macro} methodology to stochastic differential equations for the purpose of numerically solving oscillatory evolution equations. The models we consider are addressed in a wide spectrum of regimes where oscillations may be slow or fast. We show that through an ad-hoc transformation (the micro-macro decomposition), it is possible to retain the usual orders of convergence of Euler-Maruyama method, that is to say, uniform weak order one and uniform strong order one half. We also show that the same orders of uniform accuracy can be achieved by a simple integral scheme. The advantage of the micro-macro scheme is that, in contrast to the integral scheme, it can be generalized to higher order methods.

International audience; 12 The Early Cretaceous topographic evolution of Transbaikalia was largely governed by the 13 tectonic evolution of the Mongol-Okhotsk orogenic belt. The collapse of the Mongol-Okhotsk 14 orogen triggered the formation of metamorphic core complexes and associated extensional basins, 15 widespread throughout Transbaikalia, North Mongolia, and North China. Numerous lithofacies proximal sediment sources. Distal provinces also made a contribution to sedimentation indicating 29 the rise of a positive topography characterizing the exhumation of the metamorphic core 30 complexes. Overlying fine-grained formations indicate a significant smoothing of the topography, 31 suggesting that from middle Aptian, Western Transbaikalia developed in a relatively calm tectonic 32 regime. We also show that the basins of Transbaikalia were formed both in conjunction with the 33 exhumation of metamorphic cores complexes and reactivated structural sutures. Revised data on 34 dinosaur fauna and palynology, together with the dating of host deposits, provide insights on the 35 Early Cretaceous paleoenvironmental evolution.

International audience; Adaptation of wild insects to an artificial laboratory environment goes hand in hand with changes in their genetic diversity and symbiotic communities. This can have a profound effect on mass rearing of insects since their biological quality and mating competitiveness might be reduced. Patterns of genetic and symbiotic variation associated with laboratory adaptation vary among species and identifying the agents of selection that drive such patterns can be extremely helpful for pest control programmes. In the present study, we profiled the genetic and symbiotic structure of a wild Drosophila suzukii population and monitored their changes during laboratory adaptation. We employed sixteen microsatellite markers and tracked the fluctuation of their frequencies as domestication was progressing. We also used 16S rRNA sequencing to depict changes in the microbiota structure. Changes in effective and observed allele numbers and heterozygosity became evident from F10, while between F0 and F6 a gradual decline was observed. The microbiota profile of D. suzukii also formed distinct clusters during adaptation as F0 and F1 were differentiated by the rest generations and presented the highest bacterial diversity. Overall, our results showed that laboratory adaptation strongly affects both genetic diversity and bacterial communities of D. suzukii. These results can serve as a reference for the design of an area-wide integrated pest management approach with a Sterile Insect Technique (SIT) component. Rearing productivity, biological quality, and mating competitiveness of a SIT mass-reared strain should be assessed in connection with genetic and symbiotic changes occurring during laboratory adaptation.

Jurassic carbonate strata in the eastern Paris Basin exhibit several generations of faults, tension gashes and stylolites. Although their relative chronology can sometimes be determined according to cross-cutting relationships, the duration of major deformation phases and their influence on fluid flow and carbonate cementation are still uncertain. This contribution aims to clarify the timing of brittle deformation and associated calcite cementation. Tension gashes filled by calcite in Jurassic carbonates were sampled in outcrops and boreholes and dated through U–Pb geochronology. Almost all the sampled fractures were cemented during the Cenozoic period. Continuous deformation spread from c. 50 to 30 Ma. Tension gashes oriented N10° to N20° dated at 48–43 Ma show the main Pyrenean contractional stage. A second set of calcites were dated at c. 35–33 Ma and document a Late Eocene – Oligocene extension. A transition from the compressional to the extensional regime is expressed by tension gashes dated between 43 and 35 Ma. Finally, tension gashes oriented N150° to N175°, dated between 32 and 18 Ma, may result from the propagation of the horizontal stress generated by the Alpine orogen or by late Pyrenean deformation. Clumped isotope thermometry on five samples revealed both low crystallization temperatures (from 27 to 53 °C) and the meteoric origin of calcite-precipitating fluids. Our research therefore documents a continuous fracturing from Ypresian to Rupelian times, and less expressed brittle deformation during the Miocene period.

International audience; An ammonite biostratigraphy for Oxfordian in the Tlemcenian domain (northwestern Algeria) belonging to the south Tethyan margin is presented. It is based on the study of many sections located near Takhemaret and Frenda cities (Province of Tiaret). From bottom to top, the following biozones and subzones are distinguished: (i) Liosphinctes plicatilis Zone subdivided into the Cardioceras vertebrale (including the Otosphinctes arkelli Horizon) and Dichotomosphinctes antecedens subzone (including the Dichotomosphinctes antecedens Horizon); (ii) Gregoryceras transversarium Zone subdivided into four subzones: Perisphinctes parandieri, Dichotomosphinctes luciaeformis (its presence is doubtful), Larcheria schilli and Dichotomoceras rotoides subzones; (iii) Dichotomoceras bifurcatus Zone subdivided into two subzones: Dichotomoceras stenocycloides Subzone including the Dichotomoceras bifurcatoides Horizon, and the Dichotomoceras grossouvrei Subzone. The obtained results are compared and completed with those of Bou Rheddou and Bechtout (northern Tiaret city). The recorded biozones are very similar to the standard biozonation of the Upper Jurassic recognized throughout the Mediterranean region.

Pools are common features of peatlands and can represent from 5 % to 50 % of the peatland ecosystem's surface area. Pools play an important role in the peatland carbon cycle by releasing carbon dioxide and methane to the atmosphere. However, the origin of this carbon is not well constrained. A hypothesis is that the majority of the carbon emitted from pools predominantly originates from mineralized allochthonous (i.e., plant-derived) dissolved organic matter (DOM) from peat rather than in situ primary production. To test this hypothesis, this study examined the origin, composition, and degradability of DOM in peat porewater and pools of an ombrotrophic boreal peatland in northeastern Quebec (Canada) for 2 years over the growing season. The temporal evolution of dissolved organic carbon (DOC) concentration, the optical properties, molecular composition (THM-GC-MS), stable isotopic signature (δ13C-DOC), and degradability of DOM were determined. This study demonstrates that DOM, in both peat porewater and pools, presents a diverse composition and constitutes highly dynamic components of peatland ecosystems. The molecular and isotopic analyses showed that DOM in pools was derived from plants. However, DOM compositions in the two environments were markedly different. Peat porewater DOM was more aromatic, with a higher molecular weight and DOC : DON (dissolved organic nitrogen) ratio compared to pools. The temporal dynamics of DOC concentration and DOM composition also differed. In peat porewater, the DOC concentration followed a strong seasonal increase, starting from 9 mg L−1 and reaching a plateau above 20 mg L−1 in summer and autumn. This was explained by seasonal peatland vegetation productivity, which is greater than microbial DOM degradation. In pools, DOC concentration also increased but remained 2 times lower than in the peat porewaters at the end of the growing season (∼ 10 mg L−1). Those differences might be explained by a combination of physical, chemical, and biological factors. The limited hydraulic conductivity in deeper peat horizons and associated DOM residence time might have favored both DOM microbial transformation within the peat and the interaction of DOM aromatic compounds with the peat matrix, explaining part of the shift of DOM compositions between peat porewater and pools. This study did not report any photolability of DOM and only limited microbial degradability. Thus, it is likely that the DOM might have been microbially transformed at the interface between peat and pools. The combination of DOM quantitative and qualitative analyses presented in this study demonstrates that most of the carbon present within and released from the pools originates from peat vegetation. These results demonstrate that pools represent a key component of the peatland ecosystem ecological and biogeochemical functioning.

International audience; The foundations of modern quantitative geomorphology have thus been built around this paradigm of steady-state landscapes responding to progressive changes in climatic or tectonic condition. In ice-free landscapes, the evolution of continental landforms over large time scales is generally described by a competition between tectonic uplift and erosion of rivers and hillslopes. The initiation of co-seismic landslides is generally attributed to the passage of seismic waves, and in particular to the peak ground acceleration associated with volume waves. The volume of landslides is then generally obtained using empirical scaling laws with their area. Co-seismic landslides have a geomorphological impact that goes beyond the co-seismic phase. The principle of a landscape at a steady state, with a balance between the rates of erosion and uplift, needs to be reconsidered due to the amplitude and variability of tectonic and geomorphological processes during the seismic cycle

International audience; Reorganization of the Asian climate from one dominated by global planetary wind systems to a regional monsoon climate is closely related to the surface uplift of the Tibetan Plateau (TP). However, evaluating this climatic reorganization is limited by difficulty in constraining the complex, multistaged uplift of the TP and contradictory evidence regarding Asian Monsoon onset. In this Review, we summarize proxy and model evidence for Asian Monsoon initiation at different latitudes to identify the main controls on monsoon evolution. Stratigraphy and palaeoclimate proxy records indicate that the Asian climate was reorganized in a two-stage northward expansion process. At ~41 million years ago (Ma), the monsoon advanced northwards from the tropic to the southern subtropical regions (~26° N, approximately present-day Yunnan), probably driven by central TP uplift, global cooling and rapid regression of the proto-Paratethys Sea. At ~26 Ma, the monsoon expanded northwards into temperate regions (~30–36° N, equivalent to the present-day Asian Monsoon boundary), likely driven by TP growth and global warming. Additional proxy records are needed to fill regional gaps, establishing more solid boundary conditions and improving parameter constraints for climate models.

International audience; Fluoroquinolones and tetracyclines are frequently detected antibiotics in aquatic sediments. In this study, the transport of ciprofloxacin (CIP) and tetracycline (TET) was investigated in sediments from the Seine Estuary (France), under nitrate reducing conditions. Dynamic flow experiments showed that although TET and CIP strongly interacted with the sediment components through adsorption and (bio)-chemical transformation, they kept their antimicrobial activities. Less nitrate reduction was observed during the first period of breakthrough, while TET and CIP were absent in the column effluent. Batch experiments with freeze-dried vs fresh sediments showed that adsorption and abiotic degradation are the major removal processes, while microbe-driven transformation is of less importance. Whereas TET is to a large extent chemically transformed and little adsorbed in the sediment, CIP was less transformed and more adsorbed, most likely due to the great reactivity of TET with redox-active mineral surfaces. Our findings show the strong capacity of natural sediment to retain and transform antibiotics, while still maintaining their antimicrobial activity or inhibitory effect of nitrate reducing activity.

During the last glacial period, the climate shift to cold conditions associated with changes in atmospheric circulation and vegetation cover resulted in the development of large aeolian systems in Europe. On a regional scale, many factors may have influenced dust dynamics, such as the latitudinal difference between the various aeolian systems and the variability of the sources of wind-transported particles. Therefore, the assumption that the timing of aeolian deposition is strictly synchronous in Europe does not seem to be the most plausible hypothesis and needs to be evaluated. To test this assumption, the chronology of loess deposition in different European regions was investigated by studying 93 luminescence-dated loess-palaeosol sequences with their data recalculated and compiled in a single CSV file: the ChronoLoess database. Our study shows that the two major aeolian systems, the Northern European Loess Belt (NELB) on the one hand and the systems associated with the rivers draining the Alpine Ice Sheet on the other hand, developed asynchronously. The significant deposition started at about 32 ka for the NELB vs 40 ka for the perialpine loess and peaked about two millennia later for the former (21.8 ka vs 23.9 ka, respectively). This shift resulted mainly from the time lag between the maxima of the Alpine and Fennoscandian ice sheets, which acted as the primary sources of fine-grained particles through glacial abrasion. The major geomorphic changes that resulted from the development and decay of the Fennoscandian and British-Irish ice sheets also played an important role. Particularly, ice sheet coalescence during the LGM diverted meltwater fluxes through the Manche River and provided vast amounts of glacial particles available for deflation in the western NELB. The period during which the maximum Mass Accumulation Rate was reached for each loess-palaeosol sequence is relatively homogeneous in the NELB and ranges from 30 ka to 19 ka, whereas it is more scattered in the perialpine systems (>60 ka to 14 ka). This probably resulted from a combination of factors, including the asynchrony of maximum valley glacier advances and local geomorphic factors.

International audience; The 12 m thick sequence of calcareous slope deposits and palaeosols exposed in a quarry at Verteuil (southwest France) has been studied and dated by optically stimulated luminescence. Emphasis was given to the identification and characterisation of palaeosols through geochemistry and micromorphology. The main clastic units, separated by major unconformities, were dated to MIS 6, MIS 5-4 and MIS 3-2. Stratified deposits ('grèzes litées'), consisting of alternating diamictic and matrix-free clastic beds and attributed to stacked stone-banked solifluction lobes, developed mainly after ca. 40 ka, i.e. during late MIS 3 and MIS 2. MIS 3 is recorded as a palaeosol complex including two humic A horizons overlying a chromic cambisol associated with burrows of ground squirrels, while MIS 5 corresponds to a reworked rubified chromic cambisol. Overall, this sequence shows similarities with the clastic deposits found in regional cave porches and rock shelters, strongly suggesting that anthropogenic activities did not significantly modify the climate-driven sedimentary and soil-forming processes at the Palaeolithic sites.

International audience; The present study aimed to characterise the bacterial, fungal and parasite gut community of the invasive bee Megachile sculpturalis sampled from native (Japan) and invaded (USA and France) regions via 16S rRNA and ITS2 amplicon sequencing and PCR detection of bee microparasites. The bacterial and fungal gut microbiota communities in bees from invaded regions were highly similar and differed strongly from those obtained in Japan. Core amplicon sequence variants (ASVs) within each population represented environmental micro-organisms commonly present in bee-associated niches that likely provide beneficial functions to their host. Although the overall bacterial and fungal communities of the invasive M. sculpturalis in France and the co-foraging native bees Anthidium florentinum and Halictus scabiosae, were significantly different, five out of eight core ASVs were shared suggesting common environmental sources and potential transmission. None of the 46 M. sculpturalis bees analysed harboured known bee pathogens, while microparasite infections were common in A. florentinum, and rare in H. scabiosae. A common shift in the gut microbiota of M. sculpturalis in invaded regions as a response to changed environmental conditions, or a founder effect coupled to population re-establishment in the invaded regions may explain the observed microbial community profiles and the absence of parasites. While the role of pathogen pressure in shaping biological invasions is still debated, the absence of natural enemies may contribute to the invasion success of M. sculpturalis.

One quarter of the living beings are located beneath our feet but we know very little of them (FAO, 2020). This statement will perhaps quickly change because the soils are now on the political agenda. For France, soil is mentioned in the Green Pact at European level (Montanarella, 2020) and in the country government's Biodiversity Plan. The law on soil health is also planned for 2023 (Köninger et al., 2022). However, as its biological component remains poorly understood, the indicators used by stakeholders give only a biased view of soil quality (Lehmann et al., 2020). It is therefore urgent to catch up on the knowledge of soil biodiversity in order to establish benchmarks for bioindicators, based on standardised data.In parallel, the French Biodiversity Office working on the linkages between all French terrestrial biodiversity monitorings, pointed out the absence of soil biodiversity monitoring in France.Rather than creating de novo a soil biodiversity monitoring, it was preferred to add biodiversity surveys to the already existing French Soil Quality Monitoring Network (RMQS), hereafter called the RMQS-Biodiversity. The RMQS covers a big part of the French territory (the continental part as the over seas) since 2000. Every year, 180 study sites are sampled. Thus, all the sites are sampled in 10-12 years (Jolivet et al., 2018). The RMQS provides data about all physical and chemical aspects of soils. Regarding the soil biological component, microorganisms and enzymatic activities are also surveyed. By the past, soil fauna was studied on around 100 sites but the experience was not maintained (Imbert et al., 2021). Moreover, a major strength of the RMQS is the network of involved people included the 12 field teams, the coordination team, the funders and data users (researchers and stakeholders).To implement the biological measurements, we gathered a group of experts on soil biodiversity. As meetings go by, five protocols were defined to assess the most exhaustively possible the soil biodiversity taxa and three functions (soil macroporosity, enzymatic activities and organic matter degradation). Then, the protocols were tested in real conditions on 30 RMQS study sites with the field teams. The duration of each protocol was quoted to clearly assess the costs.We concluded that the biodiversity sampling of 180 RMQS study sites per year, would cost around 1 000 000 euros. We propose five scenarios giving compromises between financial costs and data quality.If the RMQS-Biodiversity is maintained, it would make possible: 1) to advance on the still too partial knowledge of soil biodiversity and its interactions with agricultural practices and 2) based on the knowledge acquired, to develop bioindicators and their benchmarks, in order to accurately assess soil quality, in the context of Soil Health (Lehmann et al., 2020). A complete soil monitoring, including its three components (physical, chemical and now biological), would thus provide a relevant tool to policy- makers to reach reconciling human activities and soil integrity.

Radial microcracks surrounding retrogressed SiO2 inclusions in UHP garnets are key microstructural observations allowing to constrain the mechanisms of exhumation of ultra-high-pressure (UHP) rocks. The major challenge lies in identifying whether the microstructures formed during their ascent from mantle depths, or as a consequence of transient variations in the tectonic regime. By combining petrographic observations, petrochronological data and numerical thermo-mechanical modelling, we show that radial cracks around SiO2 inclusions in ultrahigh-pressure garnets from Dora Maira are caused by ultrafast decompression during the early stage of exhumation (< 0.5 Ma). Decompression rates higher than 10-14 s-1 are, for the first time, inferred from natural microstructures independently of current petrochronological estimates1. We demonstrate that the SiO2 phase transition generates shear stresses sufficiently large to trigger plastic yielding, resulting in the generation and propagation of radial and bent shear bands, mimicking the fractures observed in UHP garnet. Our results question the traditional interpretation of the exhumation from great depth of ultrahigh-pressure tectonic. Instead, we propose that such ultrafast decompression rates are related to transient changes in the stress state of the buried continental lithosphere, favoring an exhumation mechanism involving nappe stacking. 1 Rubatto, D. & Hermann, J. Exhumation as fast as subduction? Geology 29, 3–6 (2001).

International audience; The monitoring of temporal variabilities of groundwater flows is a critical point in many hydrogeological contexts, especially for the characterization of coastal aquifers, sub-surface heterogeneities or else groundwater/stream interactions. Considering the lack of available methods, we investigate the possibility of monitoring and quantifying groundwater fluxes variations over time through active-Distributed Temperature Sensing (DTS) measurements. Active-DTS, consisting in heating a fiber optic cable, performs very well for investigating the spatial distribution of groundwater fluxes but the method has never been tested to continuously monitor groundwater fluxes changes. In this context, both numerical simulations and sandbox experiments were performed in order to assess the sensitivity of temperature elevation to variable flow conditions. Results first demonstrate that when a flow change is followed by a long-enough steady-state flow stage the temperature elevation stabilizes independently of previous fluxes conditions. Thus, the stabilization temperature can easily be interpreted to estimate groundwater fluxes using the analytical model commonly used under steady flow conditions to interpret active-DTS measurements. Under certain flow conditions, depending on the nature of flow variations, the approach also allows the continuous monitoring of fluxes variations over time. If instantaneous flow changes occur, the superposition principle can even be used to reproduce the temperature signal over time. In summary, we demonstrated through these preliminary results the possibility of for monitoring and/or quantifying the temporal dynamic of groundwater fluxes at different temporal scales including diurnal and periodic fluxes variations, which open very interesting perspectives for the quantification of subsurface processes.

Determination of the depositional age of sediments provides the basis for much of the current understanding of tectonic processes, paleoclimate, and other aspects that relate to time. Integrated the high-resolution magnetostratigraphy with independent means of age control (e.g., biostratigraphy, tephrostratigraphy), the age model of the sedimentary sequences can generally be constrained. However, as the paleomagnetic correlation to the Geomagnetic Polarity Time Scale (GPTS) is usually non-unique, magnetostratigraphy alone usually leads to dramatically different age models for the siliclastic sequences in the absence of fossils or volcanic ash layers, likely resulting in diverse tectonic and paleoclimate reconstructions. This challenge presented by different age models is well-exemplified in the debated Cenozoic terrestrial strata in Central Asia, resulting in competing models that account for the growth of the Tibetan plateau and its association with aridification history of Central Asia. Here we develop a new approach to evaluate the age model of the tephras- and fossils-free strata by checking the potential link between syntectonic sedimentation in the basin and the rapid exhumation of basement rocks. By comparing the initiation of growth strata with the onset timing of the rapid exhumation revealed by the low-temperature thermochronology, we validate this method in the regions (e.g., Zagros fold-and-thrust belt and Ruby Mountains metamorphic core complex) where the age models for the strata have been well-constrained. Applying this approach to the debated age models of the strata in the Tarim and Qaidam basins, we constrain the depositional age of Paleogene syntectonic strata, indicating a Paleocene-Eocene initial and an Oligocene-Miocene intensified mountain building process along the northern margin of the Tibetan plateau. Integrating the timing of Paleogene tectonism along the northern Tibetan plateau with Proto-Paratethys Sea fluctuations history, we highlight the significant role of tectonism in the retreat of proto-Paratethys Sea as well as its influence on the aridification in Central Asia.

International audience; In continental subsurface environments, biogeochemical reactions drive nutrient delivery, deep microbial life and mineral weathering, with crucial importance in the critical zone. Current models often simplify groundwater transport, using the residence time approach or hillslope models. However, increasing observations suggest that the nature, location and efficiency of reactions are strongly affected by groundwater 3D flow patterns, chemical gradients and subsurface heterogeneity. Here, we investigate how hydrological and geological structures control where and when biogeochemical reactions occur in the deep critical zone. For this purpose, our approach integrates long-term and widespread local observations in a catchment-scale framework and is based on data from two critical zone observatories of the French OZCAR national network. The first study took place in Guadeloupe (Obsera), where we integrated geophysical, hydrological and geochemical data in a reactive-hydrogeological model to simulate the 3D structure of groundwater flow paths and weathering. We found that the downstream evolution of the river chemistry is controlled by the pattern of hydrogeological circulations and by the depth of the weathering front. Furthermore, the calibrated 3D model allowed the delimitation of areas where weathering occurs and we showed that active weathering is restricted to catchment-areas where downward groundwater flows are deep. The second study focused on the dynamics of dissolved oxygen (DO) in a fractured aquifer at the Ploemeur catchment (Bretagne, France). Deep and intermittent inputs of DO in groundwater were observed, enabling the reaction of DO with dissolved Fe2+, in turn sustaining the development of deep microbial communities. In this study, we designed a simple model to simulate jointly the depth-distribution of DO and Fe2+ and to investigate the hydrological and geological factors controlling the DO depth-distribution. We found that the reducing capacity of the bedrock and the mean fluid transit time are the main parameters to explain and predict the depth of the oxic-anoxic transition in crystalline environments. In this presentation, we will provide new perspectives to observe and understand the origin of subsurface biogeochemical reactions and we will illustrate key processes that breakdown classical assumptions of reactive groundwater models.

Duricrusts are hard elemental layers forming in tropical and subtropical regions. Different types of duricrusts exist, including calcretes, silcretes and ferricretes (or iron duricrusts), that differ by their composition and, most likely, their formation mechanism. In places such as Africa, Australia or Brazil, we can observe them capping hills and protecting landscapes, thus being an important part of regional geomorphology. Their formation is highly dependent on climate and requires strong seasonal precipitation cycles, enabling transport and accumulation of elements during wet seasons and precipitation and hardening during dry seasons. However, it is also known that duricrusts form in tectonically quiet environments, and multiple tens of thousands of years are needed to form centimetres to metres thick elemental layers. Two hypotheses for duricrust formation exist, namely the water table (or horizontal) hypothesis and the laterite (or vertical) hypothesis. Yet, until recently, no quantitative (numerical) model exists that represents either of them. We presented last year (Fenske et al, 2022) a model based on the water table hypothesis. Here we present a second model based on the laterite hypothesis and compare the predictions of the two models. Although the models we propose are potentially applicable to a wide range of duricrusts, we will concentrate here on the formation of ferricretes.Laterites are a type of regolith covering around 33\% of land surfaces. The thickest lateritic profiles are found in the centre of continental cratons, where they evolved for millions of years. The main process responsible for laterisation is weathering, the process transforming bedrock into regolith. During weathering rocks progressively lose their structure, elements are dissolved, re-precipitated, leached, or transported, leading to progressive porification and compaction. Subsequently, from the weathering front to the surface, a typical lateritic profile is made of coarse grained and then fine grained saprolite, a mottled zone and at the top, an indurated cover, the ferricrete. We recently developed a numerical model for duricrust formation according to the laterisation hypothesis (LT model). In this model, iron duricrusts are genetically linked to the bed rock. Material from the bedrock are transformed and leached within a given vertical column of rocks but are also moved vertically due to tectonic uplift. We assume that as the regolith ages, it undergoes a process of transformation that is proportional to mean fluid flow and that leads to hardening and compaction. As material is constantly removed from the regolith layer, the model is dependant on a constant material input (through uplift and, potentially, surface erosion) to reach sufficient laterisation for ferricrete formation. Comparing predictions of the laterisation (LT) model to those of the water table (WT) model, we observe that they require slightly different tectonic regime, with the WT model most efficient during period of complete quiescence and the LT model needing a slow constant rate of base level fall to produce duricrusts. The two models also differ by the geometry of the duricrusts they predict and, in particular, the depth at which duricrust forms in the regolith (at or above the water table level).

Integrating hydrology in Landscapes Evolution Models (LEMs) is challenging. The drainage-area-based solutions, where drainage area weighted by precipitation rates approximate the amount of water flowing through every location, accumulates drainage-area downstream following the topographic gradient and has been empirically linked to observed discharge. While straightforward and computationally efficient, it implicitly includes hydrology without calculating discharge or water height. A more sophisticated solution consist in the direct calculation of the shallow water equation, which explicitly approximates water height and discharge using physics-based equations. While the latter bears more information about the channels and floodplains dynamics, it is inherently limited to short time scales and is computationally more expensive, with numerical time step typically of the order of the second – making its use for long-term LEMs particularly challenging. Here, we present GraphFlood, a fast iterative method computing river depth and water discharge in 2D on a digital elevation model (DEM). This new method leverages the Directed Acyclic Graph (DAG) nature of water flowing on surface topography to iteratively solve for the 2D shallow water equation without the inertia terms. The main idea of the algorithm is to find the correct water surface height by iteratively balancing discharge input and output. At each iteration, we first use fast DAGs-related algorithms to calculate flow accumulation on the hydraulic surface. We use this as an approximation of the discharge input. Then, the discharge output is calculated using the Manning flow resistance equation, in a manner similar to the Floodos model (Davy et al., 2017). The divergence of the discharges increments the water height. The iterative process is repeated until reaching a stationary state, i.e. a static field of water height and discharge representing an equilibrium state. Note that this method can be slightly modified to solve flood wave propagation by approximating the input discharge function of the immediate upstream neighbours. Water depths obtained with the stationary solution were validated against an analytical solution in the case of a rectangular channel and with the Floodos model for natural DEMs. Compared to previous hydrodynamic models, the main benefits of GraphFlood are its simplicity of implementation, which mainly requires a classical flow routing algorithm, and its efficiency. While case-dependent, our tests suggested a ~10 times speed-up compared to Floodos model (Davy et al., 2017) which was already significantly faster than other hydrodynamic models. Moreover, the computational time scales a little more than linearly with the number of cells, which makes GraphFlood a suitable solution even for DEMs larger than 106 – 107 cells. We demonstrate the suitability of the method for integrating realistic hydrology in a wide range of topographic and morphometric analyses (e.g. channel width assessment, floodplain delineation, Flint-Morisawa metrics) and in LEMs – even for longer timescales.

From the end of the Carboniferous onwards, the over-thickened and hot Variscan crust collapsed (late-orogenic collapse), accompanied by the rise of high-grade metamorphic domes along low-angle detachment faults and the development of mainly half-graben or pull-apart type asymmetric intramountain coal basins.These Carboniferous-Permian late orogenic basins widely developed around 300 Ma and were filled with siliciclastic continental material, accompanied by a widespread intrusive and extrusive magmatic activity. These basins crop out in the internal parts of the belt south of the Variscan Front in several limited locations in and around the Variscan basement of Western Europe (Massif Central, Vosges-Black Forest, Alps, Harz). They occur as small isolated and disconnected “basins” with incomplete sedimentary series. Their present-day area does not reflect their initial extent and thickness, which can be explored by studying their subsurface prolongation beneath their Meso-Cenozoic sedimentary covers.We propose a geological overview of the late Variscan Carboniferous-Permian Brécy basin (SW Paris basin, France), based on the reprocessing and interpretation of vintage seismic lines and related deep boreholes. We aim (i) to discuss its sedimentary filling, which is hidden beneath the Meso-Cenozoic cover of the Paris basin, (ii) to present thickness maps of its 3.9 km-thick sedimentary filling, and (iii) to describe its structural extensional features related to a syn- to post-rift tectonic scenario. We finally compared our new results to other Carboniferous-Permian deposits in France (to discuss its lateral correlation with neighboring basins) and northwest Europe, suggesting that the Brécy Basin may represent - due to its thickness and location - a missing link between late Variscan basins in southern and northern Europe.

International audience; Natural peatlands represent 1/3 of the world C soils and contribute significantly to sequestration of atmospheric CO2 by assimilation and storage of non-well decomposed organic C, due to their specific predominant vegetation such as Sphagnum species. However, they are encountering anthropogenic-induced pressures that disturb their structure (implying shift of vegetation), with potential consequences on their carbon sink function. In an attempt to mitigate this effect, restoration experiments were undertaken at La Guette peatland, a hydrologically disturbed temperate Sphagnum-peatland invaded by vascular plants, which is now a carbon source. Hydrological restoration was performed by blocking drains with dams and vegetation restoration was undertaken by either i) removing first 5 cm of peat (bare plots) or ii) removing first 5 cm of peat and transferring Sphagnum mosses (Sphagnum plots). To study the effect of these experiments, CO2 and CH4 fluxes together with environmental variables and vegetation indices were monitored from 2014 to 2017 in 24 2mx2m plots. The annual carbon budget for each plot was estimated using empirical models. Preliminary results show that the hydrological restored site presented lower annual mean CO2 emissions than the undisturbed site. In addition, Sphagnum plots had the lowest annual mean CO2 emissions followed by bare peat plots then by intact plots. Hence, the results of these models provide evidence that hydrological and vegetation restorations favour the return to the C sink function of the peatland. However, there is still a need for larger-scale studies to better estimate the effect of restoration activities on peatland greenhouse carbon budgets.

International audience; Terra Antiqua is a plugin for QGIS to make paleogeographic reconstructions with a user-friendly graphical interface. The goal of Terra Antiqua is to make paleogeographic reconstructions accessible and attractive to a much wider range of users, typically Earth and Life scientists and students, without extensive expertise in programming and GIS analyses. Yet Terra Antiqua can also be attractive for GIS developers as our reconstruction algorithms are accessible through application programming interfaces (APIs), open source Github repository and written in python with open standards (e.g. OpenLayers, OGC, GDAL). Starting from physiographic features and datasets rotated back to the desired reconstructed age (typically using Gplates), the previous release of Terra Antiqua offered a set of primary tools to run the main steps of a global reconstruction (1. Combine topo-/bathymetry, 2. Set Paleoshorelines, 3. Modify topo/bathymetry and 4. Create topo/bathymetry) and secondary tools to improve and enhance the result. From this first simple release we are incrementally adding tools and features inspired by various methods developed by experienced paleogeographers. The new release, Terra Antiqua 2.0, has integrated a new set of options on the existing tools, including the ability to create physically realistic geomorphic features. These new options will be presented within the controversial example of the reconstruction of the India-Collision and the development of the Tibetan-Himalayan orogen. Several reconstructions stemming from competing topographic and geodynamic models are thus compared and assessed based on compiled datasets including updated paleoaltimetry.

Active faults accommodate tectonic plate motion through different slip modes, some stable and aseismic, others characterized by the occurrence of large earthquakes after long periods of inactivity. Although the slip mode estimation is of primary importance to improve seismic hazard assessment, this parameter inferred today from geodetic observations needs to be better constrained over many seismic cycles. From an analytical formulation developed for analyzing fault scarp formation and degradation in loosely consolidated material, we show that the final topographic shape generated by one earthquake rupture or by creep (i.e., continuous slip) deviates by as much as 10–20%, despite a similar cumulated slip and a constant diffusion coefficient. This result opens up the theoretical possibility of inverting, not only the cumulated slip or averaged slip rate, but also the number of earthquakes and their sizes from scarp morphologies. This approach is all the more relevant as the number of rupture events is limited. Estimating the fault slip history beyond a dozen earthquakes becomes very difficult as the effect of erosion on scarp morphology prevails. Our modeling also highlights the importance of trade-offs between fault slip history and diffusive processes. An identical topographic profile can be obtained either with a stable fault creep associated with rapid erosion, or a single earthquake rupture followed by slow erosion. These inferences, derived from the simplest possible diffusion model, are likely to be even more pronounced in nature.

Since the end of the 19th century, geomorphologists have been on a relentless quest to unravel the mysteries of landscape evolution and explain the diversity of the resulting forms. However, a quantitative model of landscape morphodynamics that is relatively universal and applicable at various time scales still eludes us. This raises an important question: are we, geomorphologists, dumber than the average scientist, or is landscape evolution particularly complex to decipher? ChatGPT tells us that, indeed, landscape evolution is complex. As for many natural phenomena, the complexity of landscape evolution results from 3 elementary components: processes, stochasticity, and heterogeneity. Process geomorphology tackles the complex morphodynamics emerging from the diversity and interactions of physical, chemical, and biological processes that shape the Earth. Stochastic geomorphology addresses the role of fluctuations in the drivers of landscape evolution, such as the frequency-magnitude distribution of precipitation events, landslides, earthquakes, or fires. Heterogeneous geomorphology embraces the variable nature of the properties of landscape elements on which geomorphic processes operate or that they create. This includes, for instance, the distribution of grain sizes, the diversity of rock type, the fractal nature of rock fractures, or the spatial variations in vegetation size and type.Accounting for all these sources of complexity, inasmuch as they can be quantified, is an untractable problem resulting in models of little explainability. Therefore, hypotheses had been and must be formulated to simplify the problem of landscape evolution comprehension and modeling. There is, arguably, a long tradition of emphasizing process complexity to explain landscape dynamics, neglecting or simplifying both stochastic fluctuations and heterogeneity. In this lecture, I shall discuss this view, emphasizing the now well-established importance of stochastic fluctuations, and how little we know of the role of heterogeneity.On this latter topic, I shall illustrate with a variety of examples how time series of high-resolution and high-precision topographic data (4D data) offers unprecedented insights into landscape morphodynamics. Beyond quantifying and detecting a variety of processes and their temporal fluctuations, 4D data allow a systematic quantification of the heterogeneity (e.g., vegetation, grain size, ...) of landscape elements, and spatial variability of geomorphic rates, thus bringing us closer to formulating the role of heterogeneity in landscape dynamics. Yet, this goal can only be achieved if tools to harness the complexity and richness of high-resolution topographic data are developed and made available.Keywords: fluvial incision, landslides, floods, salt marshes, topo-(bathymetric) LiDAR, numerical modeling, machine learning.

Being the world’s largest freshwater resource, groundwater is at a continuous risk of overabstraction for human water use. Beside substantial drops in groundwater levels that are the consequence of unsustainable groundwater abstraction, which modify the recharge/discharge relationships between large-scale hydrogeological units, this anthropogenic hydraulic forcing is also responsible for changes in thermal regimes within the critical zone. While the impact of global groundwater pumping on the hydrogeological cycle has long been demonstrated, we still have insufficient knowledge on the influence of human activities on groundwater temperatures and, as a consequence, on stream thermal regimes and groundwater quality.In this contribution we discuss temperature anomalies that develop in the shallow subsurface as a result of localized groundwater extraction. We study different hydrogeological settings, i.e., porous and fractured aquifers, that we explore via numerical modelling and comparison with field observations. In the field, we use repeated temperature-depth borehole profiles separated by decades, the advantage of which is that differencing the temperature logs for individual boreholes yields real temperature change and eliminates steady-state sources of curvature. Thus, it enables us to detect changes in subsurface thermal regimes, resulting from transient conditions, i.e., climate change and changes in groundwater hydrodynamics.

The Cenozoic history of the Tibetan Plateau topography is critical for understanding the evolution of the Indian-Eurasian collision, climate, and biodiversity. However, the long-term growth and landscape evolution of the Tibetan Plateau remains ambiguous, it remains unclear if plateau uplift occurred soon after the India-Asia collision in the Paleogene or later in the Neogene. As the landscape evolution is controlled mainly by mountain uplift and surface processes, the present-day river profiles and the drainage basin geometries preserve important information that can be extracted to infer the long-term history of mountain uplift with numerical models. Here we focus on the southeastern (SE) Tibetan Plateau where three of the world’s largest rivers draining the Tibetan Plateau (the Yangtze, Mekong, and Salween Rivers, i.e., Three Rivers) have incised deep valleys with distinctive geomorphic signatures. We reproduce the uplift history of the SE Tibetan Plateau using a 2D landscape evolution model, which simultaneously solves fluvial erosion and sediment transport processes in the drainage basins of the Three Rivers region. Our model was optimized through a formal inverse analysis with a large number of forward simulations, which aims to reconcile the transient states of the present-day river profiles. The modeling results were ultimately compared to existing thermochronologic and paleoelevation datasets to help decipher between competing tectonic models that predict contrasting topographic evolutions. Our results suggest initially low elevations during the Paleogene, followed by a gradual southeastward propagation of topographic uplift of the plateau margin until present day. The modeling thus does not support Paleogene formation of the SE Tibetan Plateau with a major subsequent degradation via upstream fluvial erosion. The scenario with pre-existing high-elevation plateau or plateau degradation will result in much wider river channels with knickpoints that propagated upstream much further away from the plateau margin compared to observed river profiles. The quantitative constraints on landscape evolution achieved based on drainage patterns in SE Tibet indicate a powerful tool potentially applicable to other regions to infer important implications for the evolution of Indian-Eurasian collision, Asian monsoons, and biodiversity, as well as the geodynamic forces involved in collisional orogens.

Eclogitization constitutes one of the most emblematic transformations in continental subduction zones, where conversion of initially dry lower crustal rocks into eclogite facies rocks correlates with the occurrence of seismogenic events. This reaction is generally considered to occur at high pressure conditions during hydration of dry granulite. Several models using « ad hoc » diffusion equation exist to model this hydration process and the consequences of reaction-induced changes in terms of rheology and density. However, to our knowledge, there is no quantitative model allowing to physically explain how fluids propagate inside a dry rock (i.e. with no porosity at all) and how reaction-induced alteration front widens over time. In this study, we therefore propose a new fully coupled hydro-chemical model wherein a two-phase flow model is coupled with the eclogitization reaction. We use a mass conservative approach, solving total mass and solid mass equations, in a closed isothermal system. Fluid and solid densities are calculated with lookup tables from equilibrium thermodynamics. Our model shows that a fluid pressure pulse generates a pressure gradient that can be associated with the densification reaction when the pressure required for the eclogitization is reached. This reaction generates a large increase in porosity (0 to ~16%) and subsequent porous fluid flow inside the initially dry granulite. This process is then sustained as long as the fluid pulse is maintained, and ends shortly after the fluid pressure pulse stops. However, high pressure within the reacted area can persist for a long period of time. A parametric study allowing to constrain both the duration and the widening of the reaction area is proposed as well as an application to the emblematic case study of the eclogitized granulites of Holsnoy (Bergen Arcs, Norway).

International audience; The knowledge acquired on the exhumation of the Pyrenean chain and the evolution of the adjacent foreland basins makes this Alpine-type domain a good laboratory to better constrain a full sediment routing system in a compressive context and to apprehend the driving processes controlling the sediment routing in space and time. This integrated approach aims at enhancing our basin mastering approach as well as improving our predictions of reservoir properties. This Source-to-Sink study seeks to understand the evolution of sedimentary routing from the Source (orogenic relief, craton, basin recycling) through the transfer zone (peripheral or internal to the basin) to the final sink (flexural basin, deep turbiditic margin). Within this new cartography, we propose to compile the data over the entire peri-Pyrenean domain. We produced large scale quantitative and qualitative maps to better observe and interpret the tectonic, climatic and surface processes impacts of the SRS behavior. These maps include kinematic reconstructions of the Iberian-European-Mediterranean system, restored sequential cross-sections, history/magnitude of exhumation by thermochronology, source tracking, characterization of weathering and erosion surfaces, synthesis of the major structures activity, paleogeographic reconstructions, analysis of sedimentary geometries and transport directions as well as the quantification of volumes preserved in the basins. Their interpretation is combined with a time representation along the routing system, linking classical basin wheeler diagram representation to source erosion and lithologies to obtain a continuous view on the sediment journey. The time steps chosen for these 5 maps account for the different stages of tectono-sedimentary evolution of the peri-Pyrenean system at the early-, syn- and post-orogenic stages. The compilations carried out compare exhumed domains and sedimentation zones in terms of fluxes and volumes and make it possible to map the routing systems and point out the main drivers for the surface evolution during the construction/destruction cycle of an orogen. Research work financed and carried out as part of the BRGM-TOTAL Source-to-Sink program

The study of heat transport in porous media has recently attracted a lot of attention due to the wide range of industrial and geological applications, yet the impact of the structural heterogeneity of naturally occurring aquifers on their hydraulic and thermal properties is often disregarded. In that regard, a novel application of phosphor thermometry to porous media is proposed with the aim of examining under which conditions the validity of existing thermal transfer models in complex natural saturated porous media can be questioned. This experimental technique relies on monitoring the temperature-dependent luminescence properties of solid phosphor particles seeded into the fluid as tracers, using light sources and cameras. It offers the possibility of characterizing quantitatively the interaction between flow and heat transport processes at the pore scale in transparent analog porous media, with minimal interference and from spatially-resolved measurements, hereby overcoming the technical limitations of current experimental techniques, which are constrained to point temperature measurements.Here, as proof of concept, we present a demonstration experiment performed on a slow-moving flow in a synthetic porous medium with a heterogenous size distribution, and using YAG:Cr3+, a thermographic phosphor with a temperature sensitivity exceeding 0.3%/K [1]. The measurements are performed using a modulated light source and are recorded at a sampling rate of 1 kHz during continuous injection of an aqueous solution which is initially at a constant temperature, different from that of the resident solution. The results show the dynamics of the spatial temperature distribution in the porous medium with a precision of ±0.3°C.[1] J. L. Bonilla and B. Fond, "Phosphor thermometry using the phase-shift method: optimization and comparison with decay time method," 2022.

Repeated alpine glaciations during the Quaternary partly reached far into the foreland and caused profound landscape changes beyond glacial margins in northern Switzerland. Climate-driven glacier growth and decay and commensurate variations in water and sediment delivery caused river systems to aggrade and to incise, leading to the widespread occurrence of glacio-fluvial deposits (Deckenschotter) and associated terraces. Mapping and numerical dating of these depositional complexes increasingly offer insights into the spatial patterns and timing of Quaternary glaciations, and associated changes in (glacio-)fluvial dynamics. An improved understanding of how fluvial systems respond to glacial-interglacial cycles will help to assess the erosion potential around repository sites of nuclear waste over the next one million years. In this study, we contribute to close this research gap using numerical landscape evolution modelling (LEM).We use EROS, a numerical landscape evolution model, which implements a particle-based approach to simulate water and sediment fluxes that interact with topography through erosive and depositional actions. Unlike LEMs based on the stream-power incision law, the method solves the 2D shallow water equations with both basal and lateral erosion and deposition, which allows for variations in width and lateral mobility of rivers; these variations induce changes in the transport capacity of the sediments that cause specific patterns of deposition and erosion to emerge. We adjusted the model so that it is capable to run over 1 Myrs, and imposed boundary conditions that - informed by estimates on longterm erosion rates – reflect rock uplift and plausible variations in water and sediment fluxes following a 100-kyrs glacial cycle. Our model relies on digital elevation models and sediment thickness data with 60 m spatial resolution and is applied to the Hochrhein river between Stein am Rhein and Basel and the Aare river downstream of the area, where Limmat and Reuss enter.Our simulations show that the model reproduces widespread aggradation, reworking of the sediments by highly laterally mobile, braided river systems and incision during periods of increased runoff and low sediment availability.Our model setup and parametrization features several uncertainties. For example, the capacity of rivers to laterally erode strongly determines the thickness and extent of depositional complexes lining the Hochrhein and Aare system. Also, our model is sensitive to temporally varying boundary conditions of water and sediment input about which precise estimates are lacking. Regardless, the more detailed and realistic representation of hydraulic and sediment transport processes by EROS compared to conventionally used landscape evolution models at this spatial and temporal scale provide the opportunity to test different hypotheses using numerical experiments and link the results to field evidence. Further sensitivity analyses and uncertainty quantification will enable us to use our model as simulation tool to hindcast and investigate the behaviour of fluvial system in response to different tectonic and climatic scenarios, thus helping to better understand potential spatial patterns of and sediment assemblages within widespread glacio-fluvial deposits.

Stream water chemistry at catchment outlets is commonly used to infer the flowpaths of water through the catchment and to quantify the relative contributions of various flowpaths and/or end-members during, e.g., storm events. For this purpose, the number and nature of these flowpaths or end-members are commonly defined a priori as part of the experimental design and previous knowledge, and their contributions are calculated based on the dynamics of the stream chemistry, with the inherent assumptions and uncertainties of this approach. Here, we present a methodology, which inverts this classical approach. We use the variability of the stream chemistry data to determine the minimum number of end-members needed and, more specifically, whether two end-members would be sufficient. In this methodology, we analysed the concentration-concentration relationships of several major ion combinations on the storm-event scale for multiple events, using a multi-year, high-frequency (< 60 minutes) timeseries of the major cations and anions from the outlet of two small (0.8 – 5 km²) french catchments with contrasting land-use (forest and mixed farming-cropping productions). The results indicate that a large number of storm-events (up to 92%) could be interpreted as the result of only two end-members, depending on the catchment and the ion combination used. These findings might help to revise some of the perceptual understandings of flowpath or end-member contributions in catchments during storm-events. In addition, they might stimulate the discussion about the definition of end-members or flowpaths in catchments, especially with regard to variable hydrological contributions.