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Background: With the use of non-objective measurement, adherence to growth hormone (GH) therapy has been reported suboptimal in a large proportion of patients, and poor adherence has been shown to affect short-term growth response in patients receiving GH treatment. Objective: The Easypod™ electronic device allows objective measurement of adherence. In this study, we report 3-year prospective adherence data of the Italian cohort of naïve GH deficient (GHD) children extrapolated from the Easypod Connect Observational Study (ECOS) database. Patients and methods: Seventy-three GHD children naïve to GH treatment were included in the analysis. 22 Italian centers participated in the study. Results: Mean adherence rate was consistently above 85% across the 3-year observation period. Particularly, mean adherence was 88.5%, 86.6%, and 85.7% after 1, 2 and 3years, respectively. Mean (± SD) height-SDS increase after the first year was 0.41 (± 0.38). Conclusions: The majority of naïve GHD children starting GH treatment with Easypod maintained an adherence rate > 85% up to 3years. Easypod is a useful tool to follow-up patients’ adherence allowing timely intervention to improve optimal treatment for these patients.

We present hypersequent calculi for the strongest logics in Lewis’ family of conditional systems, characterized by uniformity and total reflexivity. We first present a non-standard hypersequent calculus, which allows a syntactic proof of cut elimination. We then introduce standard hypersequent calculi, in which sequents are enriched by additional structures to encode plausibility formulas and diamond formulas. Proof search using these calculi is terminating, and the completeness proof shows how a countermodel can be constructed from a branch of a failed proof search. We then describe tuCLEVER, a theorem prover that implements the standard hypersequent calculi. The prover provides a decision procedure for the logics, and it produces a countermodel in case of proof search failure. The prover tuCLEVER is inspired by the methodology of leanTAP and it is implemented in Prolog. Preliminary experimental results show that the performances of tuCLEVER are promising.1

Background Although many studies emphasize the importance of using oxygen saturation (SpO2) targets in the NICUs, there is a wide variability in used saturation ranges among centers. Primary aim was to draw a representative picture on how the management of oxygen monitoring is performed in the Italian NICUs. Second aim was to identify healthcare-professionals related factors associated with oxygen targeting in the preterm population. Methods Cross-sectional study with data collection via an electronic survey form. A questionnaire containing pre-piloted and open questions on monitoring and management of the SpO2 was administered to neonatologists across the network of the Italian Society of Neonatology. The questions focused on: the infrastructure, specific training, healthcare professionals and patients-related factors. The results of the survey were anonymously collected, summarized and analyzed. Results Out of 378 questionnaires, 93 were correctly filled. Thirty-six different SpO2 ranges were observed. Centers using written standard operating procedures on oxygen management and SpO2 monitoring maintained a correct average range of SpO2 90–95%, avoided hyperoxia and reconsidered saturation targets in relation to comorbidities. 39.8% of responders disabled alarms during neonatal care. One center used biomarkers for complete monitoring of neonatal oxygenation status. Conclusions There is considerable variation in SpO2 targets for preterm infants in the Italian NICUs. Standard operating procedures and specific training for health care personnel are the main factors playing a role for the correct maintenance of the recommended oxygen targets in preterms.

Background/Objectives: Early diagnosis and a low-Phe diet significantly improved prognosis of PKU patients whose management is now-a-day mostly focused on preventing nutritional imbalances and resulting comorbidities. Puberty is a turning point for the risk to develop overweight and bone quality impairment. The present study aims to evaluate body composition and bone quality in prepubertal and pubertal PKU patients. Subjects/Methods: This is an observational, prospective study on an historical cohort of patients with PKU aged between 4.1 and 18 years, with early diagnosis and continuous protein-restrictive diet treatment. Bioimpedance, weight measurements, height, body mass index calculation, and quantitative ultrasound were collected. Sexual maturity was evaluated by using the Tanner staging. Results: Thirty PKU patients (14 prepubertal, 16 pubertal) were included in the study. Mean BMI was within the normal range in both groups, although fat content was higher in prepubertal, whereas lean mass was higher in the pubertal group who had also a higher total protein content. Among QUS parameters, bone quality index and broadband ultrasound were lower in prepubertal children than in adolescents, with a Z-score BQI within the osteopenia range in both of them. Conclusions: Pubertal patients with PKU develop a higher lean mass and protein content. If on one hand the high non-Phe protein intake in the pubertal period may promote increase in bone mineral quality, on the other hand the higher protein retention, typical of this period, may increase the risk for hyperinsulinism and glucose intolerance in later life. Adjusting dietary management by modulating total protein intake in the peripubertal period could result in better management of PKU patients.

National audience

International audience; We present tuCLEVER, a theorem prover for the strongest conditional logics of counterfactual reasoning introduced by Lewis in the seventies. tuCLEVER implements some hypersequent calculi recently introduced for the system VTU and its main extensions. tuCLEVER is inspired by the methodology of leanT^AP and it is implemented in Prolog. Preliminary experimental results show that the performances of tuCLEVER are promising.

Immune checkpoints refer to a plethora of inhibitory pathways of the immune system that play a crucial role in maintaining self-tolerance and in tuning the duration and amplitude of physiological immune responses to minimize collateral tissue damages. The breakdown of this delicate balance leads to pathological conditions, including cancer. Indeed, tumor cells can develop multiple mechanisms to escape from immune system defense, including the activation of immune checkpoint pathways. The development of monoclonal antibodies, targeting inhibitory immune checkpoints, has provided an immense breakthrough in cancer therapy. Immune checkpoint inhibitors (ICI), initially developed to reverse functional exhaustion in T cells, recently emerged as important actors in natural killer (NK)-cell-based immunotherapy. Moreover, the discovery that also helper innate lymphoid cells (ILCs) express inhibitory immune checkpoints, suggests that these molecules might be targeted on ILCs, to modulate their functions in the tumor microenvironment. Recently, other strategies to achieve immune checkpoint blockade have been developed, including miRNA exploiting systems. Herein, we provide an overview of the current knowledge on inhibitory immune checkpoints on NK cells and ILCs and we discuss how to target these innate lymphocytes by ICI in both solid tumors and hematological malignancies.

/ Les résidus médicamenteux sont peu éliminés par les stations de traitement des eaux usées (STEU) et se retrouvent dans les écosystèmes aquatiques provoquant une contamination chronique persistante des eaux de surface et des sédiments. Parmi ces résidus, les antibiotiques peuvent également s'accumuler dans le biote et ont été détectés à tous les niveaux du réseau trophique (Aubertheau et al. 2017). Dans l'environnement, la présence d'antibiotiques est en particulier susceptible d'altérer les fonctions et la structure des communautés microbiennes et plus spécifiquement d'exercer une pression de sélection sur les bactéries, avec un risque avéré de développement d'antibiorésistances. Dans ce contexte, nous appliquons une approche multi-compartiments (eau de surface, périphyton, sédiment) et multi-sites incluant des écosystèmes lotique (rivière Arve) ou lacustre (lac Léman) afin de comparer la réponse des communautés microbiennes naturelles issues de sites présentant des expositions contrastées aux résidus de médicaments en provenance de STEU. Pour chaque site étudié, nous avons évalué le potentiel fonctionnel des communautés microbiennes du périphyton et des sédiments (photosynthèse, activités hétérotrophes extra-cellulaires) ainsi que leur tolérance à 2 antibiotiques (ciprofloxacine, sulfaméthazine) suivant une approche PICT et leur capacité à biodégrader les sulfonamides. Ces analyses biologiques seront complétées par l'étude du résistome et de la structure des communautés puis mises en relation avec les concentrations des résidus médicamenteux dans le périphyton, les sédiments et les eaux de surface. Les premiers résultats ont notamment mis en évidence dans le lac Léman une plus forte tolérance microbienne à la ciprofloxacine au site proche du rejet de STEU qu'au site plus protégé. Ces premiers résultats seront complétés et contribueront à une meilleure connaissance de la répartition des antibiotiques et des antibiorésistances dans les différents compartiments aquatiques ainsi qu'à une meilleure compréhension des liens entre structure du résistome et fonctions associées à ces résistances (tolérance ou biodégradation) chez les communautés microbiennes.

/ L'adaptation in situ des communautés microbiennes aux contaminants est le résultat de différents processus favorisant la sélection des espèces tolérantes et la disparition des espèces sensibles. De nombreuses études ont démontré l'intérêt de caractériser cette capacité d'adaptation pour diagnostiquer un niveau d'exposition à un contaminant chimique suffisant pour induire une modification de la communauté microbienne étudiée[1], suivant le concept PICT (Pollution Induced Community Tolerance[2]). Récemment, la mesure de la tolérance au cuivre de communautés microbiennes benthiques issues de sédiments superficiels provenant de différentes rivières nous a permis de mettre en évidence une relation exponentielle entre la tolérance microbienne au cuivre et les niveaux de contamination in situ dans ce compartiment. Ces premiers résultats suggèrent l'existence d'une tolérance microbienne basale qui permettrait de dépasser l'approche relative (i.e. la comparaison de sites contaminés avec une référence) utilisée jusqu'à présent. Néanmoins, l'application de l'approche PICT au sédiment, peu pris en considération jusqu'alors, a mis en évidence une problématique propre à cette matrice. En effet, les caractéristiques de cette matrice (granulométrie, quantité et qualité de matières organiques...) peuvent affecter la bio-disponibilité des contaminants lors des tests de toxicité et influencer leurs résultats indépendamment de la tolérance microbienne. Afin de s'affranchir de cet « effet matrice », nous avons comparé plusieurs méthodes pour détacher les communautés microbiennes du sédiment en conservant au maximum leur viabilité et activité (prérequis pour pouvoir réaliser les tests de toxicité). L'homogénéisation mécanique dans un tampon pyrophosphate a donné les meilleurs résultats et son application à des communautés microbiennes exposées au laboratoire à différents niveaux de cuivre a permis de mettre en évidence une acquisition de tolérance en lien avec l'exposition.

/ Les résidus médicamenteux sont peu éliminés par les stations de traitement des eaux usées (STEU) et se retrouvent dans les écosystèmes aquatiques provoquant une contamination chronique persistante des eaux de surface et des sédiments. Parmi ces résidus, les antibiotiques peuvent également s'accumuler dans le biote et ont été détectés à tous les niveaux du réseau trophique (Aubertheau et al. 2017). Dans l'environnement, la présence d'antibiotiques est en particulier susceptible d'altérer les fonctions et la structure des communautés microbiennes et plus spécifiquement d'exercer une pression de sélection sur les bactéries, avec un risque avéré de développement d'antibiorésistances. Dans ce contexte, nous appliquons une approche multi-compartiments (eau de surface, périphyton, sédiment) et multi-sites incluant des écosystèmes lotique (rivière Arve) ou lacustre (lac Léman) afin de comparer la réponse des communautés microbiennes naturelles issues de sites présentant des expositions contrastées aux résidus de médicaments en provenance de STEU. Pour chaque site étudié, nous avons évalué le potentiel fonctionnel des communautés microbiennes du périphyton et des sédiments (photosynthèse, activités hétérotrophes extra-cellulaires) ainsi que leur tolérance à 2 antibiotiques (ciprofloxacine, sulfaméthazine) suivant une approche PICT et leur capacité à biodégrader les sulfonamides. Ces analyses biologiques seront complétées par l'étude du résistome et de la structure des communautés puis mises en relation avec les concentrations des résidus médicamenteux dans le périphyton, les sédiments et les eaux de surface. Les premiers résultats ont notamment mis en évidence dans le lac Léman une plus forte tolérance microbienne à la ciprofloxacine au site proche du rejet de STEU qu'au site plus protégé. Ces premiers résultats seront complétés et contribueront à une meilleure connaissance de la répartition des antibiotiques et des antibiorésistances dans les différents compartiments aquatiques ainsi qu'à une meilleure compréhension des liens entre structure du résistome et fonctions associées à ces résistances (tolérance ou biodégradation) chez les communautés microbiennes.

International audience; Aquatic ecosystems are generally subjected to multiple perturbations due to simultaneous or successive combinations of various natural and anthropogenic environmental pressures. To better assess and predict the resulting ecological consequences, increasing attention should be given to the accumulation of stresses on freshwater ecosystems and its effects on the vulnerability of aquatic organisms, including microbial communities, which play crucial functional roles. Here we used a microcosm study to assess the influence of an experimental warming on the vulnerability of phototrophic and heterotrophic periphytic communities to acute and chronic copper (Cu) toxicity. Natural periphytic communities were submitted for 4 weeks to three different temperatures (18, 23, and 28°C) in microcosms contaminated (at about 15 µg L-1) or not with Cu. The vulnerability of both phototrophic and heterotrophic microbial communities to subsequent acute Cu stress was then assessed by measuring their levels of sensitivity to Cu from bioassays targeting phototrophic (photosynthetic activity) and heterotrophic (β-glucosidase and leucine aminopeptidase extracellular enzymatic activities) microbial functions. We postulated that both the increase in temperature and the chronic Cu exposure would modify microbial community structure, thus leading to changes in the capacity of phototrophic and heterotrophic communities to tolerate subsequent acute exposure to Cu. Our results demonstrated that the influence of temperature on the vulnerability of phototrophic and heterotrophic microbial communities to Cu toxicity can vary greatly according to function studied. These findings emphasize the importance of considering different functional compartments and different functional descriptors to better assess the vulnerability of periphyton to multiple stresses and predict the risks induced by multiple stressors for ecosystem balance and functioning.

International audience; The first French-Swiss workshop on ecotoxicology of freshwater sediment communities was co-organized by the French Research Institute of Science and Technology for Environment and Agriculture (Irstea) and the Swiss Centre for Applied Ecotoxicology (Ecotox Centre EAWAG-EPFL) in Villié-Morgon (Beaujolais Region, France) on April 27-28, 2017. The workshop brought together scientists working in different fields of expertise (ecotoxicologists, ecologists, environmental chemists...), environmental stakeholder groups and managers, as well as economic players (start-ups and consultancies) to better connect research needs of potential end-users with research outputs. The objectives of this workshop were (i) to establish the state of the art of research in the characterization of sediment contamination and in the evaluation of the effects on sediment-associated biological communities and ecosystem functioning and (ii) to give an overview of the French and Swiss regulations dealing with the assessment of contaminated sediments in freshwater ecosystems. The ultimate goal was to collectively identify research needs and knowledge gaps, as well as to highlight ways to improve the ecotoxicological assessment of sediments in freshwater environments by further considering the structure and functions of associated microbial and invertebrate communities.

International audience; While many metals are known to accumulate in sediments, knowledge about the resulting ecotoxicological effects on sediment microbial communities is scarce. The present study aimed at evaluating the structural and functional impact of chronic exposure to environmental concentrations of copper (Cu) and arsenic (As), alone or mixed together, on river sediment microbial communities. Natural uncontaminated surface sediments collected in a French River (Ain) were spiked with As and Cu at a nominal concentration of 40 mg/kg and then were exposed for 21 days in laboratory channels with overlying waters. The response of heterotrophic microbial communities to metals was evaluated both in terms of genetic structure (using ARISA analysis) and functional potential (using exo-enzymatic, metabolic and qPCR analyses). A pollution induced community tolerance (PICT) approach was also performed to assess if the exposure led to an increase in the capacity of microbial communities to tolerate metals. Our results showed rapid and marked effects of Cu alone on the structure and the functions of the exposed communities. Chronic Cu exposure also induced an increase in community tolerance to Cu, as observed by PICT measurement using beta-glucosidase activity. In contrast, the effects of As were mostly undetectable. Under mixture exposure (Cu+As), the effects were similar or higher than those provoked by Cu alone, depending on the measured parameter. Altogether those findings reveal that metals accumulation in sediments can impact exposed microbial communities thus affecting their functional role in aquatic ecosystems.

International audience; In the past decades, an increasing number of anthropogenic contaminants such as pesticides, antibiotics or drug residues has reached the aquatic ecosystem, leading to chronic chemical perturbations. While improvements in chemical analyses allow detecting a large diversity of micro-pollutants at low chemical concentrations, biological analyses are still required to estimate the effects of contaminants in the environment. In particular, the PICT (Pollution Induced Community Tolerance) approach allows detecting chronic exposure to specific contaminants based on microbial communities’ adaptation capacity. Thus, an increase in microbial tolerance to a pollutant is likely to reflect the adaptative response of microbial communities to such a perturbation. Acute toxicity tests performed in laboratory on natural communities can reveal this tolerance acquisition and point to a direct link between tolerance and pollutant exposure. For instance, Pesce et al. 2016 highlighted a decrease in microbial community tolerance to the herbicide diuron, in a freshwater stream, following diuron ban. The PICT approach provides information on both environmental contamination and ecological effect and thus can be used to reveal chronic effects of an environment contamination as well as to follow microbial response after a perturbation. However, currently toxicity tests on natural microbial communities are time-consuming which limits the number of contaminants or sites tested simultaneously. In this context, the aim of this work was to optimize toxicity tests performed on periphytic communities (e.g. time reduction, process miniaturization) to eventually provide a battery of toxicity tests to detect contaminant effects on community tolerance. Furthermore, those improved tests were applied, during a monitoring program, on a freshwater stream impacted by pesticides to reveal differences in exposure. The optimization of toxicity tests on microbial communities will improve the use of PICT approach in environmental assessment.

SSCI-VIDE+CARE+NHY:MBM:SPR:CGO; International audience; Surfaces coated with biogenic surfactants exposed to the atmosphere are ubiquitous and are commonly present on aerosol particles, cloud droplets, buildings, plants, and oceans. As shown in the past, photochemical reactions taking places at these air/water interfaces lead to unique chemical pathways, producing volatile organic compounds (VOCs) and leading to secondary organic aerosol formation. Here, photochemical processes at the air/water interface of biofilm-containing solutions were studied, demonstrating abiotic VOC production from authentic biogenic surfactants under ambient conditions [1]. Using a combination of online-APCI-HRMS and PTR-ToF-MS, unsaturated and functionalized VOCs were identified and quantified, giving emission fluxes comparable to previous field and laboratory observations. Interestingly, VOC fluxes increased with the decay of microbial cells in the samples, indicating that cell lysis due to cell death was the main source for surfactants, and VOC production. In agreement with our previous studies, LC-MS measurements of the liquid phase suggested the presence of fatty acids and known photosensitizers, possibly inducing the observed VOC production via peroxy-radical chemistry. Up to now, such VOC emissions were directly attributed to high biological activity in surface water. However, our results suggest that abiotic photochemistry can lead to similar atmospheric emissions, especially in low biologically-active regions. Furthermore, chamber experiments suggested that oxidation (O3 /OH-radicals) of the photochemically-produced VOCs leads to aerosol formation and growth, possibly affecting atmospheric chemistry and climate-related processes, such as cloud formation or the Earth’s radiation budget.[1] M. Brüggemann et al., Faraday Discussions, 2017, in press.

International audience; Biological communities in aquatic environments most commonly face multiple stress, where natural andanthropogenic stressors often act jointly. Their interactions are most easily assessed using short cycleorganisms such as periphytic diatoms.In this experiment, we analyzed the combined effects of copper exposure and warming on diatomsuccessions over 6 weeks. Natural biofilm collected in winter was left to grow in mesocosms exposed orunexposed to realistic Cu concentrations at four different temperatures. Separate and joint impacts ofthe two stressors were determined through structural and functional endpoints.Both temperature and copper influenced the biological responses; their interaction, when significant,was always antagonistic. Diatom communities gradually changed with rising temperature. Under copperexposure, the dominant Planothidium lanceolatum was superseded by Achnanthidium exiguum, whichaccounted for about 70% relative abundance in the warmest conditions (18–23◦C). Tolerance to copperwas derived from dose-response curves based on photosynthesis inhibition. Cu-induced communitytolerance was always found, but it decreased with warming and time.Biodiversity loss associated with lower Cu tolerance under combined Cu exposure and increasing tem-peratures evidences the major influence of cumulative stressors on aquatic health. These results highlightthe crucial interplay between environmental stressors, which are expected to intensify with climatechange.

Benthic ecosystems are important areas both in terms of biodiversity and functioning. They are receiving direct or indirect inputs from the water column or from the watershed and may therefore be accumulating zones for contaminants. Many benthic and epibenthic organisms may be exposed to these substances, with as consequences, disruption of ecological traits and functions at the ecosystem level such as changes in benthic community structure and ecosystem functioning. However, knowledge about the ecotoxicological effects of accumulated contaminants at the benthic community level is scarce. Accordingly, the present study aimed at assessing the functional impact of chronic exposure to environmental concentrations of metals on natural sediment communities. We evaluate the usefulness of assessing/studying feeding activity and organic matter breakdown as endpoints, using two kinds of artificial organic matter substrates.

International audience; Science of the Total Environment By measuring levels of tolerance to toxicants in microbial communities using functional toxicity tests under controlled conditions, pollution-induced community tolerance (PICT) approaches offer an effect-based tool to assess the ecological risk of chemicals in aquatic systems. However, induced tolerance of exposed microbial communities cannot always be attributed solely to the presence of toxicants as various environmental factors, such as temperature, can also be involved. Several PICT studies have been conducted to assess the effects of copper (Cu) on phototrophic periphyton, but little is known about the influence of temperature on the response of these microbial communities to acute and chronic exposure to Cu. Here, we report on a microcosm approach to assess the effects of two contrasting temperatures (18°C and 28°C) on (i) the baseline level of Cu tolerance in non-Cu-exposed phototrophic periphyton (i.e. effect of temperature on tolerance baseline), (ii) Cu tolerance acquisition by phototrophic periphyton in response to a 3-week chronic exposure to Cu at a nominal concentration of 60µgL-1 (i.e. effect of temperature on PICT selection) and (iii) tolerance measured during short-term toxicity tests (i.e. effect of temperature on PICT detection). The aim was to evaluate how temperature conditions during the different phases of the PICT approaches may modify the causal relationship between chronic Cu exposure and measured Cu tolerance levels. Our results evidence the influence of temperature both on the basal capacity of phototrophic periphyton to tolerate subsequent exposure to Cu (i.e. influence on tolerance baseline) and on its capacity to acquire tolerance following chronic exposure to Cu (i.e. influence on PICT selection). Hence temperature must be considered when using PICT to establish causal links between chronic Cu exposure and effects on phototrophic periphyton.

International audience; Changes in agricultural practices related to environmental policies such as the European Water Framework Directive should lead to a decrease in pesticide contamination levels in rivers draining agricultural areas. However, there is still a need for biological tools to evaluate resulting ecological changes, namely to evaluate ecological recovery following the improvement of surface water chemical quality. Accordingly, the main purpose of this study was to assess the relevance of a pollution-induced community tolerance (PICT) approach in natural phototrophic biofilms to estimate microbial community recovery following a decrease in diuron contamination due to the ban of the use of this herbicide on vineyards. To this end, we performed a 3-year field study (2009-2011) in the Morcille River (France), located in the French Beaujolais wine region. This river was frequently contaminated by diuron (among other organic and inorganic pesticides), with increasing concentrations downstream. Following the ban on diuron, imposed in December 2008, a progressive decrease in diuron concentrations was observed in the Morcille River. While the mean annual tolerance levels measured at the low contaminated station remained relatively constant over years, a clear and significant decreasing trend was observed at the medium and high contaminated stations during the survey. This temporal evolution revealed a direct link between a change in agricultural practice due to the ban of diuron and an increase in the sensitivity of phototrophic biofilms to this herbicide. This finding brings further new evidence that PICT has great potential to detect microbial community recovery following chemical restoration due to changes in the agricultural use of pesticides.

International audience; Grab sampling may be scarcely adequate to evaluate the impact on surface waters of pesticide used in agriculture because of its poor spatiotemporal representativeness compared to the high variability of the contamination patterns. Indeed, it is still not easy to link the effect of agricultural practice changes to water quality at the catchment scale. Furthermore, biological indicators may also be useful in addition to pesticide concentration determination to evaluate their impact on ecosystems. In this way, the contribution of new integrative tools has been evaluated. Passive samplers and biological indicators have been applied together at the catchment scale so as to identify their coherence and complementarity. The tested chemical tools are the passive-SBSE (Stir Bar Sorptive Extraction) dedicated to hydrophobic to moderately hydrophilic compounds and the POCIS (Polar Organic Chemical Integrative Sampler) dedicated to hydrophilic compounds. As concerns biological approach, it consisted in the in situ deployment of i) caging methodology with a highly ecological relevant amphipod species, Gammarus fossarum, coupled to the measurement of toxicity markers (acetylcholine esterase inhibition, feeding rate) and ii) the study of microbial and macro-invertebrate communities (measurement of leaf decomposition rates) as well as phototrophic periphytic communities (measurement of Pollution Induced Community Tolerance). These tools have been applied during june 2014 (corresponding to vineyard and corn period of application) in two contrasted agricultural catchments. The Ardières basin situated in the Beaujolais region (France) is submitted to viticulture pressure and a marked pesticide contamination has already been highlighted. Three measurement stations have been chosen so as to search for a contamination gradient from upstream to downstream. The Coise basin is located in the Monts du Lyonnais (France) in a zone of mixed farming breeding with a predominance of meadows, corn and cereals. Three measurement stations have been selected on three sub-catchments corresponding to differentiated pesticide use. In total, 49 pesticides (28 herbicides, 9 fungicides and 12 insecticides) have been analyzed as well as potential confusing parameters (metal(oïd)s, nutrients, temperature, luminosity, water flow). Results show the high coherence of chemical and biological tools responses. All of them were able to reflect the spatial contamination gradients as well as the specific contamination and impact associated to each agro-pedo-climatical context. A weekly exposure also permitted to take into account the temporal variability of the contamination according to flood occurrence. Finally, their sensitivity, reactivity and integration capacity make these tools relevant and promising to assess agricultural pesticide impact on surface water in addition to grab sampling.

45e congrès du Groupe Français des Pesticides, Versailles, FRA, 27-/05/2015 - 29/05/2015; National audience; Pour effectuer un diagnostic de la contamination en produits phytosanitaires présents dans les milieux aquatiques continentaux, les gestionnaires des eaux s'appuient essentiellement sur une stratégie d'analyse chimique via une stratégie d'échantillonnage ponctuel. Mais cette méthodologie souffre d'un manque de représentativité temporelle et ne rend pas compte des effets biologiques induits par les pollutions.C'est ainsi que face à un besoin de compréhension de l'évolution spatio-temporelle et de l'impact de la contamination des milieux aquatiques, les gestionnaires se montrent aujourd'hui intéressés par les différents outils intégratifs chimiques (échantillonneurs passifs) ou biologiques (encagement de gammares, étude des communautés microbiennes) développés ces dernières années par les laboratoires de recherche, et notamment par Irstea. S'appuyant sur une convention ONEMA - Irstea, financé par le programme d'action national Ecophyto (Axe 3 Volet 4 : « Recherches sur les impacts sanitaires et environnementaux de l'utilisation des pesticides »), le projet « Développement d'outils et d'indicateurs pour mieux évaluer la chaîne pressions-impacts des pesticides sur les eaux de surface » vise notamment à évaluer ces nouveaux outils, leur complémentarité, leur opérationnalité et leur disponibilité pour les gestionnaires. A terme, ce projet ambitionne de développer un guide de mise en ½uvre de ces outils de suivi in situ pour l'appui au diagnostic de l'état et de l'impact de la contamination des eaux par les produits phytosanitaires ou à l'orientation et l'évaluation des actions correctives.Pour affiner ou consolider les méthodologies d'utilisation et d'interprétation des réponses de ces outils des applications in situ sont nécessaires. C'est dans ce cadre qu'une campagne de déploiement de ces outils a été réalisée en juin 2014 sur deux bassins versants choisis comme cas d'étude de typologie de contamination contrastée. - Le premier bassin versant choisi est celui de l'Ardières, situé dans le Beaujolais viticole, et soumis à une pression forte en produits phytosanitaires, a priori essentiellement des fongicides et insecticides. Trois points de suivi ont été sélectionnés sur la rivière, de l'amont dénué de vignes, vers l'aval de plus en plus occupé par les parcelles viticoles.- Le second bassin versant étudié est celui de la Coise, situé dans les Monts du Lyonnais, où l'élevage intensif bovin et la polyculture sont prédominants. Durant la période du mois de juin, le bassin est notamment soumis à une contamination en herbicides liée à la culture du maïs. Trois sites de suivi ont également été sélectionnés : un point sur la rivière de la Coise, et deux points sur deux affluents de celle-ci, caractérisés par des intensités d'usages agricoles différenciées.Sur ces sites d'études, 49 pesticides (28 herbicides, 9 fongicides et 12 insecticides) ont été recherchés par 2 échantillonneurs passifs distincts : la passive-SBSE (Stir Bar Sorptive Extraction) échantillonnant des molécules hydrophobes à moyennement hydrophiles et le POCIS (Polar Organic Chemical Integrative Sampler) échantillonnant une majorité de molécules hydrophiles. Ces échantillonneurs placés dans le milieu réalisent un échantillonnage en continu, et améliorent ainsi la représentativité de la qualité moyenne du milieu en permettant d'obtenir une concentration intégrée sur le temps d'exposition du capteur.Parallèlement, l'utilisation de bio-indicateurs a consisté i) d'une part dans le déploiement de gammares encagés (stratégie de monitoring actif) avec l'inhibition de l'acétylcholinestérase et le taux d'alimentation comme marqueurs étudiés car sensibles aux phytosanitaires, et ii) d'autre part dans l'étude des réponses des communautés autochtones (monitoring passif) à la présence de toxiques via la mesure de leur impact sur les communautés microbiennes et de macroinvertébrés (mesure de la dégradation de litières végétales), ainsi que sur les biofilms phototrophes péryphitiques (tests de toxicité aiguë basé sur l'approche PICT, « Pollution Induced Community Tolerance »).Le déploiement des échantillonneurs passifs a permis de caractériser le type de contamination des deux bassins versants et d'identifier des pressions différenciées suivant les sites. Sur l'Ardières un gradient de concentrations d'amont en aval en fongicides et insecticides a été mis en évidence à mesure que la surface en vignes augmente, traduisant bien la géographie et le contexte agricole du bassin. Sur le bassin versant de la Coise, une contamination en herbicides maïs est observée, avec des concentrations distinctes suivant les sous-bassins versants, en cohérence avec l'occupation du sol et la taille des bassins versants amont.Par ailleurs, les échantillonneurs passifs ont intégré des pics de contamination fugaces directement liés à des épisodes de crue, mettant en avant la présence de certaines molécules souvent mal échantillonnées par prélèvement ponctuel (par exemple l'acétochlore sur la Coise, des insecticides organo-phosphorés sur l'Ardières). Les bio-indicateurs ont permis de caractériser l'impact toxique de ces contaminations contrastées dans le temps et entre les deux bassins. Ainsi sur l'Ardières une diminution progressive de la biomasse fongique d'amont en aval est observée à mesure que les concentrations en fongicides augmentent. En aval, où les concentrations d'insecticides organo-phosphorés sont importantes, une forte inhibition de l'acétylcholinestérase chez des gammares encagés est observée. Les taux d'alimentation des gammares encagés et des communautés de macro-invertébrés autochtones démontrent une forte toxicité en aval de la rivière. Sur la Coise, l'inhibition alimentaire observée sur les gammares encagés a démontré des impacts biologiques variables dans le temps et dans l'espace sur le bassin, en rapport avec la caractérisation de la contamination réalisée grâce aux échantillonneurs passifs ; des tests de toxicité aiguë réalisés sur le biofilm phototrophe ont également montré une augmentation de tolérance vis-à-vis de l'acétochlore révélant une adaptation in situ des communautés péryphitiques à cette molécule (ou à d'autres herbicides présentant le même mode d'action), et prouvant ainsi un effet sur les communautés algales naturelles dans le milieu.Ces premiers résultats mettent en exergue la grande cohérence des réponses des différents outils, leurs apports spécifiques en complément des échantillonnages ponctuels et leur capacité à rendre compte de variations spatiales ou temporelles de la contamination (en nature de substances et en niveau de concentration). Ces essais seront consolidés sur les mêmes sites en 2015 et complétés par la mise en ½uvre des outils sur un nouveau bassin versant à dominante grandes cultures (bassin du Charlet au sud de Clermont Ferrand).

In june 2014, various integrative tools were applied and tested in rivers of differentiated agricultural catchments to evaluate their interest and limits to assess the impact of agricultural practices on surface water contamination by pesticides. In fact, these tools can relieve deficiencies of grab sampling which is classically used in the monitoring networks established to answer the WFD requirements. Especially, passive samplers can provide a more representative information due to their integrative measurement over the duration of the sampler's immersion. Biomonitoring tools (caged gammarids, study of native microbial communities) can inform on the global effect of contaminants. The results of their combined implementation show the high coherence of chemical and biological tools responses. Especially, they were able to reflect the spatial (gradient up to downstream) and temporal variability (flood event) of the contamination by pesticides and to highlight existing biological impacts which was consistent with the agro-pedo-climatical context of each studied catchment. Their sensitivity, reactivity and integration capacity make these tools relevant and promising to better assess agricultural pesticide impact on surface water in addition to grab sampling.; Durant le mois de juin 2014 des outils intégratifs d'évaluation in-situ de la contamination de l'eau en pesticides et de ses effets biologiques ont été déployés et testés dans des rivières de bassins versants agricoles aux contextes agro-pédo-climatiques différenciés, afin de mieux cerner leurs intérêts et limites pour évaluer l'impact des pratiques phytosanitaires sur les cours d'eau. Dans ce sens, ces outils permettent de pallier certaines limites de l'échantillonnage ponctuel plus classiquement réalisé dans le cadre des réseaux de surveillance de la qualité chimique et écologique des masses d'eau. En particulier, les échantillonneurs passifs, en fournissant une concentration intégrée sur la durée de leur immersion, livrent une information plus représentative de la qualité moyenne du milieu vis-à-vis des substances phytosanitaires et améliorent donc l'interprétation des résultats en termes d'évolution spatiale ou temporelle de la contamination, en lien avec l'évolution des pratiques agricoles. Les outils biologiques (gammares encagés, étude des communautés microbiennes autochtones) renseignent plus largement sur les effets toxiques des substances en présence sur les organismes aquatiques. Les suivis réalisés ont prouvé l'aptitude de ces outils chimiques et biologiques à discriminer des typologies de pression différentes (contextes polyculture/viticulture), à rendre compte de la variabilité spatiale (gradient amont/aval, hiérarchisation de sous-bassins versants) et temporelle (effet des crues) de la contamination par les pesticides. De plus, les outils biologiques déployés ont permis de conforter ou de nuancer le suivi chimique apportant ainsi des éléments de diagnostic importants quant à l'estimation d'impacts globaux ou plus spécifiques aux pesticides sur la qualité biologique des milieux aquatiques. L'intérêt d'envisager leur utilisation pour améliorer les diagnostics de la contamination et évaluer l'efficacité de plans d'action est mis en avant.

International audience; Stream and lake ecosystems in agricultural watersheds are exposed to fungicide inputs that can threaten the structure and functioning of aquatic microbial communities. This research analyzes the impact of the triazole fungicide tebuconazole (TBZ) on natural biofilm and plankton microbial communities from sites presenting different degrees of agricultural contamination. Biofilm and plankton communities from less-polluted (LP) and polluted (P) sites were exposed to nominal concentrations of 0 (control), 2 and 20 μg TBZ L-1 in 3-week microcosm experiments. Descriptors of microbial community structure (bacterial density and chlorophyll-a concentration) and function (bacterial respiration and production and photosynthesis) were analyzed to chart the effects of TBZ and the kinetics of TBZ attenuation in water during the experiments. The results showed TBZ-induced effects on biofilm function (inhibition of substrate-induced respiration and photosynthetic activity), especially in LP-site communities, whereas plankton communities experienced a transitory stimulation of bacterial densities in communities from both LP and P sites. TBZ attenuation was stronger in biofilm (60-75%) than plankton (15-18%) experiments, probably due to greater adsorption on biofilms. The differences between biofilm and plankton responses to TBZ were likely explained by differences in community structure (presence of extracellular polymeric substances (EPS) matrix) and microbial composition. Biofilm communities also exhibited different sensitivity levels according to their in-field pre-exposure to fungicide, with P-site communities demonstrating adaptation capacities to TBZ. This study indicates that TBZ toxicity to non-targeted aquatic microbial communities essentially composed by microalgae and bacteria was moderate, and that its effects varied between stream and lake microbial communities.

International audience; Diuron was found to be mineralized in buffer strip soil (BS) and in the sediments (SED) of the Morcille river in the Beaujolais vineyard repeatedly treated with this herbicide. Enrichment cultures from BS and SED samples led to the isolation of three bacterial strains transforming diuron to 3,4-dichloroaniline (3,4-DCA) its aniline derivative. 16S rRNA sequencing revealed that they belonged to the genus Arthrobacter (99% of similarity to Arthrobacter globiformis strain K01-01) and were designated as Arthrobacter sp. BS1, BS2 and SED1. Diuron-degrading potential characterized by sequencing of the puhA gene, characterizing the diuron-degradaing potential, revealed 99% similarity to A. globiformis strain D47 puhA gene isolated a decade ago in the UK. These isolates were also able to use chlorotoluron for their growth. Although able to degrade linuron and monolinuron to related aniline derivatives they were not growing on them. Enrichment cultures led to the isolation of a strain from the sediments entirely degrading 3,4-DCA. 16S rRNA sequence analysis showed that it was affiliated to the genus Achromobacter (99% of similarity to Achromobacter sp. CH1) and was designated as Achromobacter sp. SP1. The dcaQ gene encoding enzyme responsible for the transformation of 3,4-DCA to chlorocatechol was found in SP1 with 99% similarity to that of Comamonas testosteroni WDL7. This isolate also used for its growth a range of anilines (3-chloro-4-methyl-aniline, 4-isopropylaniline, 4-chloroaniline, 3-chloroaniline, 4-bromoaniline). The mixed culture composed of BS2 and SP1 strains entirely mineralizes 14C-diuron to 14CO2. Diuron-mineralization observed in the enrichment culture could result from the metabolic cooperation between these two populations.

/ La préservation des eaux de surface représente une préoccupation socio-économique majeure, symbolisée entre autres par la mise en ½uvre en 2000 de la Directive Cadre Européenne sur l'Eau (DCE, 2000), qui impose le retour au « bon état » chimique et écologique des masses d'eau d'ici à 2015. Cette contrainte législative a engendré (et engendre toujours) des besoins de recherche nombreux, notamment pour améliorer les procédures d'évaluation des risques écotoxicologiques des substances chimiques dans les masses d'eau, définir des mesures correctives visant à améliorer la qualité chimique des eaux, et développer des outils permettant de réellement mesurer le gain écologique découlant de ces améliorations. Plus récemment, le Grenelle de l'Environnement a confirmé au niveau national cette forte prise de conscience sociétale, en particulier avec l'élaboration du plan Ecophyto 2018 visant à réduire l'usage des produits phytosanitaires en agriculture. L'ensemble de mes recherches, débutées en 2003 dans le cadre de mon Doctorat, s'inscrit dans cette problématique finalisée de gestion des eaux. Elles concernent principalement les petits cours d'eau de tête de bassins versants, très sensibles aux diverses pressions anthropiques et notamment aux contaminations par les polluants chimiques organiques ou inorganiques. Dans ces milieux lotiques, la majorité de l'activité microbienne est assurée par les communautés benthiques, à savoir les biofilms se développant sur des substrats inertes (artificiels ou naturels) ou organiques (litières de feuilles) et les communautés sédimentaires. Ces communautés microbiennes interviennent ainsi dans des processus écologiques majeurs tels que la régulation des cycles biogéochimiques ou l'auto-épuration de zones contaminées (Battin et al., 2003). Elles interagissent précocement avec les substances dissoutes, et notamment les toxiques, et présentent une forte capacité à répondre rapidement aux changements environnementaux et à s'y adapter de manière transitoire ou irréversible (Sabater et al., 2007). En outre, ce sont des assemblages complexes, composés de microorganismes autotrophes et hétérotrophes qui présentent des sensibilités différentes selon le mode d'action des toxiques rencontrés. De par ces différentes caractéristiques, ils offrent donc un potentiel important pour évaluer l'impact écologique des toxiques dans les cours d'eau. Dans ce contexte, mes recherches ont pour cadre très général l'évaluation de la réponse structurale et fonctionnelle des communautés microbiennes aquatiques benthiques à des niveaux variables d'exposition à des pesticides organiques et inorganiques.

Séminaire organisé en janvier 2013 par le groupe Recherche Ecophyto; National audience; This study showed that the different compartments of the landscape within the Morcille watershed (vineyard soil, grass buffer strip soil, sediments), connected along the soil-water continuum, are able to mineralize the herbicide diuron. The purifying capability of these different compartments evolved according to the level of exposure to the contaminant. Indeed, the exposed grass buffer strip showed a better ability to mineralize diuron than the control one. The sediments of the Morcille river located nearby the buffer zone showed also a purifying capability following an upstream-downstream gradient in accordance with the one observed for the chemical quality of the water in Morcille river. The importance of the surface run-off from the vineyard to the sediments of the Morcille river for the adaptation of microbial communities to diuron-mineralization was showed. These original findings showed that although the microflora of the sediments was intrinsically able to adapt to diuron degradation, this process was favoured by soil run-off suggesting the transfer of purifying capabilities from soil to aquatic microbial communities, underlining the existence of chemical and microbiological connections of terrestrial and aquatic compartments of agro-systems. Monitoring of the evolution of the purifying capability of sediments in response to the ban of diuron uses evidenced the improvement of the chemical quality of the Morcille river. However, even four years after its ban, diuron was still detected in the river at the intermediary and downstream stations in spring and summer. Over this four-year period the purifying capability of the sediments significantly decreased. However an upstream-downstream gradient was still detectable, in accordance with the one observed for the chemical quality of the Morcielle water. The study of the diuron-degrading microbial community from the grass-buffer strip soil and from the sediments allowed isolating diuron-degrading microbial populations. Several Arthrobacter sp. isolates able to transform diuron to 3,4-dichloroaniline have been isolated from the soil and the sediments. Moreover, one additional bacterial isolate belonging to the Achromobacter genus and able to mineralize 3,4-dichloroaniline, has been isolated. A synthetic microbial consortium made of Arthrobacter sp. and Achromobacter sp. populations was shown to be able to fully mineralize diuron. These observations suggest that the microbial community able to mineralize the diuron in the soil of the buffer zone or in the sediments of the Morcille river was probably resulting from the metabolic cooperation of two bacterial populations, one transforming the diuron to 3,4-dichloroaniline while the other mineralized this intermediary metabolite. To conclude, this study shows that vineyard and grass buffer strip soils as well as the sediments of the Morcille River frequently exposed to diuron hosted a diuron-degrading microbial community able to degrade diuron. Degradation capabilities of these different compartments are variable and the level of exposure to the contaminant was shown as a major driver of the adaptation to diuron degradation. The purifying capability of vineyard and grass buffer strip soils sediments relied on the activity of microbial degrading populations developing cooperative metabolism.; Nos travaux ont montré que les différents compartiments d'un paysage viticole du site atelier de la Morcille (sol de la parcelle, bande enherbée et sédiments) connectés le long du continuum sol-eau, présentaient une aptitude à minéraliser le diuron. La capacité épuratrice de ces différents compartiments évolue en fonction du niveau d’exposition au contaminant. Ainsi la zone tampon exposée présente une meilleure aptitude à épurer le diuron que la zone tampon témoin. Les sédiments de la Morcille situés à proximité de la zone tampon présentent également une capacité épuratrice présentant un gradient amont-aval coïncidant avec le gradient amont-aval observé également pour la qualité chimique des eaux de la Morcille. L’importance du flux érosif de la parcelle viticole vers le cours d’eau pour l’adaptation des communautés microbiennes à la biodégradation du diuron a pu être mise en évidence. Ces résultats originaux montrent que même si la microflore des sédiments présente intrinsèquement la capacité d’adaptation à la biodégradation du diuron, cette faculté est améliorée par le flux érosif suggérant le transfert du potentiel épurateur du compartiment terrestre au compartiment aquatique. Ceci souligne la connectivité chimique et microbiologique des compartiments terrestres et aquatiques. L’évolution de la capacité épuratrice des sédiments de la Morcille en réponse à l’interdiction d’usage du diuron a permis de mettre en évidence une diminution de leur niveau d’exposition au diuron. Ceci confirme donc l’amélioration de la qualité chimique des eaux de la Morcille. Toutefois, quatre années après son interdiction, le diuron est toujours détecté dans les stations intermédiaires et aval aux périodes printanière et estivale. Sur la période d'étude, les capacités épuratrices des sédiments ont diminué de manière significative même si elles présentent toujours un gradient amont-aval en concordance avec la qualité chimique des eaux de la Morcille. L’étude de la communauté microbienne dégradant le diuron du sol de la bande enherbée et des sédiments de la Morcille a permis d’isoler des populations microbiennes dégradantes. Ainsi, des isolats bactériens appartenant au genre Arthrobacter sp. transformant le diuron en 3,4-dichloroaniline ont pu être isolés du sol de la bande enherbée et des sédiments. De plus, un isolat bactérien appartenant au genre Achromobacter sp. dégradant la 3,4-dichloroaniline a pu être isolé. Le consortium microbien synthétique formé d’Arthrobacter sp. et d’Achromobacter sp. est capable de minéraliser le diuron. Ces observations suggèrent que la communauté bactérienne minéralisant le diuron dans le sol de la bande enherbée et dans les sédiments repose sur la coopération métabolique de deux populations dégradantes, l’une transformant le diuron en 3,4-dichloroaniline et l’autre minéralisant cet intermédiaire métabolique. Pour conclure, ces travaux mettent en évidence que le sol de la parcelle viticole, le sol de la bande enherbée et les sédiments de la Morcille hébergent des communautés microbiennes capables d’épurer le diuron. Les capacités épuratrices de ces différents compartiments sont variables et l’un des paramètres affectant le plus ces capacités est le niveau d’exposition à la contamination. La capacité épuratrice des sols et des sédiments repose sur l’activité de populations dégradantes développant une coopération métabolique.

International audience; Periphytic diatoms are an important phototrophic component of river biofilm and are used in situ for the bioindication of pollution as well as in laboratory ecotoxicological tests to assess the toxicity of contaminants. In spring 2009, phototrophic biofilm samples mostly com-posed of diatoms were collected in a small river and their sensitivity to the herbicide diuron was estimated via pho-tosynthesis bioassays. A large difference in tolerance to diuron was demonstrated between two periphytic communities from an upstream unpolluted site and a down-stream site subjected to high seasonal contamination by pesticides. The comparison of diatom community struc-ture between sites revealed important variations of the relative abundance of some species which could explain this difference. Consequently, some of these species were isolated from the river in autumn when toxic pressure was low, and kept in culture for more than six months in uncontaminated water. Acute toxicity tests of diuron based on growth inhibition were then performed on each spe-cies. Surprisingly the sensitivities of the species as esti-mated by EC50 were almost the same. However two strains of another species that could be isolated from each site of the river showed significant differences in toler-ance to diuron and copper, another contaminant of the river. These results suggest the importance of adaptation at the intraspecific level in the induction of periphytic community tolerance to toxicants. Thus, they portend difficulties to fairly assess toxic pollution effects in situ with classical bioindication field methods at the community level.

3rd International Conference on EnvironmentalManagement, Engineering, Planning and Economics (CEMEPE 2011) & SECOTOX Conference, Skiathos, GRC, 19-/06/2011 - 24/06/2011; International audience; Periphytic diatoms are an important phototrophic component of river biofilm and are used in situ for the bioindication of pollution as well as in laboratory ecotoxicological tests to assess the toxicity of contaminants. In spring 2009, phototrophic biofilm samples composed mostly of diatoms were collected in a small river and their sensitivity to the herbicide diuron was estimated via photosynthesis bioassays. A large difference in tolerance to diuron was demonstrated between two periphytic communities from an upstream unpolluted site and a downstream site subjected to high seasonal contamination by pesticides. The comparison of diatom community structure between sites revealed important variations of the relative abundance of some species which could explain this difference. Consequently, some of these species were isolated from the river in autumn when toxic pressure was low, and kept in culture for more than six months in uncontaminated water. Acute toxicity tests of diuron based on growth inhibition were then performed on each species. Surprisingly the sensitivities of the species as estimated by EC50 were almost the same. However two strains of another species that could be isolated from each site of the river showed significant differences in tolerance to diuron and copper, another contaminant of the river. These results suggest the importance of adaptation at the intraspecific level in the induction of periphytic community tolerance to toxicants and the probably low sensitivity of bioindication methods to assess river contaminations.

Over the past 15 years, significant research efforts have been channelled into assessing the effects of organic herbicides on freshwater phototrophic microbial communities. The results of this research are reviewed herein. Main conclusions could be summarized into 5 points: - Most relevant assessments of this sort have dealt with the effects of triazine and phenylurea herbicides. Herbicides from these chemical classes are often considered to be model compounds when photosystem-II inhibitors are studied. - Until the early 2000s, the vast majority of investigations conducted to evaluate herbicide effects on phototropic microbes were performed in micro- or meso-cosms. In such studies, herbicides were usually applied alone, and often at concentrations much higher than those detected in the environment. More recently, the trend has been towards more realistic and relevant studies, in which lower herbicide concentrations were considered, and compound mixtures or successive treatments were tested. Increasingly, in situ studies are being designed to directly evaluate microbial community responses, following chemical exposures in contaminated aquatic environments. - Several biological endpoints are used to evaluate how organisms in the phototrophic microbial community respond to herbicide exposure. These endpoints allow the detection of quantitative changes, such as chl a concentrations, total cell counts or periphytic biomass, qualitative changes such as community structure to algal diversity, or functional changes such as photosynthesis, respiration, etc. They could give different and complementary information concerning the responses of microbial communities. - In addition, PICT approaches, which have generally combined functional and structural measurements, may prove to be valuable for assessing both an immediate impact, and for factoring in the contamination history of an ecosystem at the community level. - A relevant assessment of pesticides effects should include details on environmental characterization, such as abiotic parameters (light, flow speed, nutrients content) or biotic parameters (diversity and structure of biofilms), as they control the bioavailability of pesticides and the exposure of microbial communities. To improve the value of ecotoxicological risk assessments, future research is needed in two key areas: first, the effects of pollutants at the community level must be detailed (new tools and new end points), and second, more effort must be directed to reinforcing the ecological relevance of toxicological investigations.

Fixés sur des substrats immergés, les biofilms microbiens assurent un rôle écologique majeur dans les petits cours d'eau. Ils interagissent avec les substances dissoutes et les contaminants (et notamment avec les pesticides) qui peuvent modifier leur structure et leur fonctionnement par des effets directs ou indirects. Les biofilms peuvent être utilisés comme indicateurs biologiques d'une pollution (bio-indicateurs) grâce à une grande variété de descripteurs microbiens, taxonomiques ou fonctionnels. Ils apportent des informations complémentaires aux indices biologiques normalisés mis en ½uvre pour évaluer le bon état écologique des masses d'eau, au sens de la directive cadre sur l'eau. À partir de résultats obtenus dans une rivière située en zone viticole, nous proposons ici de discuter dans quelle mesure les biofilms permettent de comprendre l'effet des pesticides sur le fonctionnement des cours d'eau. / Biofilms are attached microbial assemblages on immersed substrates and play a major ecological role in stream ecosystems. Biofilms interact with dissolved substances and contaminants (such as pesticides), which can directly or indirectly affect their structure and functions. A variety of taxonomic and functional microbial indicators exist for considering biofilm as biological indicators of pollution (bioindicators). They can provide complementary information to normalized biological indices, which are used to assess the ecological status of waters, as defined by the European Water Framework Directive. Synthesizing results obtained in a river draining a vineyard area, we propose here to assess to what extent biofilms can be used to characterize pesticide effects on lotic ecosystems.

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