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International audience; In fall 2005, fish contamination by PCBs above the threshold for fish consumption was observed in the Rhone river, in the vicinity of Lyon (France). This incidental observation triggered a series of investigations on fish and sediments contamination all along the main stream, and is currently extending to tributaries. The data gathered during this still ongoing process should help managers to identify the main sources among the host of potential ones, provided distinct patterns can be identified in relation to these sources. PCB congener pattern analysis in sediments is challenging because weathering processes will modify the original patterns in several ways; moreover, at mid- or downstream sites the various upstream sources will provide mixed patterns. Classical multivariate analyses suffer several pitfalls for such pattern analysis, making it difficult to clearly discriminate among PCB sources. A combination of information about sources or weathering processes, and classification approaches, should nevertheless help to establish relationships between the patterns observed in sediment layers and the sources, yielding an approach helping to sort out priorities for further diagnosis or management actions. The method's development and the first results obtained will be presented.

L’objectif requis est de développer une méthode de caractérisation fine de l’occupation des sols le long des cours d’eau applicable immédiatement sur l’ensemble des rivières françaises à l’aide des outils de la télédétection. Avec le progrès grandissant des nouvelles technologies d’acquisition (LIDAR1, THRS2 Hyper-Spectrale,…) de plus en plus précises, informatives et répétitives, il est possible aujourd’hui de quantifier précisément l’ensemble des descripteurs hydro-morphologiques des cours d’eau (hydrologiques, morphologiques, bathymétriques). Mais l’utilisation de telles données augmenterait significativement le coût de la méthode par rapport aux approches traditionnelles et serait difficilement applicable de façon opérationnelle sur de grands territoires. Par contre, le traitement d’images optiques (satellitaires et/ou aéroportées) répond à cette demande, car il permet d’obtenir rapidement et à coût réduit une information géographique précise et homogène à large échelle au niveau des corridors. Le but de ce document est donc d’élaborer un protocole opérationnel de classification basé à la fois sur le traitement d’images optiques et des données exogènes complémentaires pour caractériser finement, à l’échelle nationale, l’occupation du sol dans les corridors rivulaires.

International audience; Les écosystèmes aquatiques continentaux constituent l'une des cibles essentielles des politiques nationales et européennes de protection et de gestion des ressources, notamment au travers de la directive cadre sur l'eau (DCE). Parmi les compartiments du milieu aquatique qu'il convient de surveiller, évaluer et protéger, les sédiments constituent un élément essentiel, d'une part parce qu'ils abritent une faune diversifiée assurant des fonctions essentielles, d'autre part, parce qu'ils constituent des sites privilégiés pour l'accumulation des polluants et peuvent constituer des sources endogènes de contamination. Actuellement, l'évaluation de la qualité des sédiments s'effectue en laboratoire par des bioessais. Toutefois, ces batteries de tests n'intègrent pas les espèces les plus sensibles et les plus représentatives de ces milieux. Les indices biotiques fournissent une information synthétique de l'évaluation de l'intégrité et de la qualité biologique des écosystèmes aquatiques. Toutefois, ces indices, comme unique outil d'analyse de la qualité biologique des systèmes aquatiques montrent certaines limites, ne permettant pas un diagnostic précis sur l'origine de la dégradation. Ainsi, notre étude s'inscrit dans une volonté croissante de produire de nouveaux éléments de surveillance et de modélisation par l'étude du fonctionnement des communautés macrobenthiques in situ via la structure bio-écologique des communautés. Elle a pour objectif principal d'évaluer les effets des sédiments contaminés par des métaux sur les communautés macrobenthiques et plus particulièrement de spatialiser les impacts sur le gradient amont/aval. Pour répondre à cette thématique, nous avons choisi d'utiliser conjointement l'analyse des structures faunistiques stationnelles et des profils bioécologiques le long d'un gradient de perturbation métallique (Cr,Cu,Ni ) et physiques (retenues au fil de l'eau) sur le Fier à Annecy. De façon surprenante, les traits bioécologiques ne permettent pas de discriminer la contamination métallique au sein des retenues. A l'inverse, la structure faunistique des peuplements stationnels montre des différences significatives dans leur composition et leur organisation. Ce constat soulève des interrogations quant à la capacité de résilience de l'écosystème et des mécanismes de compensation entre taxons qui pourraient expliquer l'absence d'effets significatifs sur la structure bioécologique des peuplements stationnels. Les communautés macrobenthiques en aval des retenues montrent des différences bioécologiques significatives caractéristiques des perturbations subies par les systèmes. En aval de la retenue non impactée par les métaux, seule la durée de vie moyenne des taxons est perturbée. On observe ainsi une diminution de la durée de vie pouvant illustrer une stratégie de recolonisation du système ou d'adaptation à la variation saisonnière du régime des eaux accrue par la modification physique du cours d'eau. La retenue impactée par les métaux induit en son aval des différences significatives dans le profil biologique des modalités de dispersion et de résistance des taxons, notamment la diminution des capacités de résistance des peuplements. D'une manière générale, l'étude de l'impact de la contamination métallique de systèmes lentiques sur la macrofaune benthique serait plus pertinente sur une échelle mésohabitationnelle nous permettant notamment de caractériser les profils bioécologiques sur sédiments.

International audience; A sociologist's and an ecologist's critical view of the Rhone river restoration programme. A ten-year physical and ecological restoration programme was defined for the Rhone River in 1998. Initially, one of its main objectives was to increase the minimum flow in several bypassed sections, with the clear goal of improving the fluvial habitat and the general ecological functioning of the river. A complex consultation process which brought together the hydropower industry, regional civil organisations, and local civil representatives was adopted to define more precisely the local measures to be taken. In the course of this process, the programme underwent a progressive change from purely ecological to more socially motivated outcomes such as improving amenity values and flood defence. We studied how increasing the minimum flow is a topic that can or cannot be discussed by the actors during the consultation process. For example, there is less discussion about the ecological value than about the economic value of the restoration programme between the hydropower industry and the local elected members. But, the various actors readily debate with the scientists about floods and sedimentary transport, linked with local knowledge. We applied a multidisciplinary approach, involving sociology and ecological sciences, to question the restoration programme and to analyse its hybrid results in terms of both the ecological and amenity values and at the same time to understand the governance process.; Il est assez commun que dans un processus de politique publique donnant large place à la concertation, l'objet initial soit déplacé. Il en est ainsi de ce cas d'étude qui, partant de la question des débits réservés, aboutit à celle de la lutte contre les inondations. Pour saisir cette trajectoire tracée aussi bien par la résistance du milieu aquatique que par les interactions humaines que celui-ci construit, il a fallu le regard croisé de l'écologue et du sociologue. L'hybridation est réussie, mais son efficacité tient aussi à une mise en critique des « utopies gestionnaires et scientifiques » qui voudraient un alignement pur et simple des différents types de savoirs et une heuristique propre à la dynamique des apprentissages sociaux. Asymétries, contradictions et ambivalences sont toujours là et la question de l'efficacité environnementale d'une gouvernance vertueuse reste posée. La Rédaction Mots-clés : restauration écologique ; concertations ; hydrosystème fluvial ; écologie et sociologie ; Rhône Résumé – Acté en 1998, le Programme décennal de restauration hydraulique et écologique du Rhône s'est fixé comme objectif principal d'augmenter les débits réservés dans les bras court-circuités du fleuve. Cet objectif était initialement pensé comme une action de restauration écologique de milieux naturels fortement perturbés. Un processus concomitant de concertations a plusieurs fois déplacé l'intérêt initial vers des projets d'élaboration d'un territoire fluvial, puis d'un outil de gestion contre les crues. L'approche interdisciplinaire appliquée, entre sociologie et écologie, interroge la capacité d'une telle action environnementale à aboutir à des résultats hybrides, relevant à la fois de l'amélioration d'un écosystème fluvial et d'un processus de gouvernance.

Bottom sediments may impair the functioning of equipments such as locks, increase the risk of flooding, or disturb habitats of aquatic species and related ecosystems functions. When dredged and accordingly abstracted from the water compartment, sediments become wastes, and are submitted regulations. Both aspects are related to the management of risks (to ecosystem functions or uses) and to their assessment. Sediment characterization entail chemical or biological approaches. Based on results obtained from these approaches, hazard characterization may be performed by means of classification methods or sediment quality standards., Pourquoi s'intéresser aux sédiments ? Leur présence a des implications pour la gestion des ouvrages, les crues, le fonctionnement des milieux (habitat important et donc déterminant pour ressources trophiques, frayères etc.) ; s'ils sont dragués, donc extraits des cours d'eau, ils entrent dans la réglementation « déchets ». Ces deux notions renvoient plus largement à la question des risques pour des fonctions de l'écosystème ou des usages, et de l'évaluation de ces risques. La caractérisation des sédiments fait appel à des méthodes chimiques et biologiques (biotests). La caractérisation du danger se base sur ces résultats, et fait appel notamment à des procédures de classification, ou des "normes de qualité environnementales".

International audience; Many studies have showed that impact by chemical contamination on benthos can be hard to demonstrate in the presence of unmeasured factors. Although influence of some habitat characteristics has been identified in parts of the St. Lawrence River, the use of benthos to assess chemically degraded sites remains uncertain. The purpose of this study is to compare the potential of various benthic macroinvertebrates community indices (diversity, richness, biotic) for assessing sediment quality in comparison with chemical sediment quality guidelines classification. In an attempt to identify possibly key factors that could be weighing in on benthic macroinvertebrates community structure, we will also regroup sites based on prospect habitat characteristics. This study is a part of a large research project aiming at developing an ERA tiered framework for sediment management, in the context of integrated management of contaminated sediment, site restoration and sustainable navigation. During falls 2004-2005, macroinvertebrates were collected in 59 sites in the St. Lawrence River, especially in its three fluvial lakes and in the harbour zone of Montreal. Organic (PCBs, PAHs, petroleum hydrocarbons), inorganic (As, Cd, Cu, Cr, Hg, Ni, Pb and Zn) contaminants and sediments characteristics (e.g. grain size, metal-binding phases, nutrients) were measured in whole sediment. The preliminary results and the implication for the development of an ERA tiered framework will be discussed.

Les effets des variations spatiales et temporelles des assecs sur les processus écologiques en rivière, telle que la décomposition des feuilles, sont peu compris. L'objectif de notre étude était de quantifier le rôle de l'intermittence (mise en eau / assec) sur la décomposition des feuilles dans l'Albarine (Bugey, France), lorsque l'écoulement est permanent. Quatre variables ont été choisies pour caractériser l'intermittence (e.g. fréquence des assecs) et ont été précisément définies par modèle hydrologique. Des sacs de litières de feuilles d'Alnus glutinosa ont été placés dans les habitats benthiques et hyporhéiques sur 10 stations réparties le long d'un gradient d'intermittence. Les sacs ont été retirés 5 fois durant 32 jours, et l'activité microbienne et les abondances des invertébrés ont été mesurées. Notre méthode était inadaptée pour l'habitat hyporhéique. En milieu benthique, les taux de décomposition des feuilles diminuent à mesure que l'intermittence augmente. L'influence de l'activité bactérienne n'est pas signifiante. Les variations des assemblages d'invertébrés en lien avec l'intermittence traduisent les variations de la décomposition. Les variations temporelles de l'intermittence structure la décomposition. Le nombre d'assecs par an est particulièrement influent. Ces résultats contribuent à une faible mais grandissante prise en compte de l'écologie des rivières intermittentes.

Summary 1. Aquatic oligochaetes appear to be pre-adapted to live in the subterranean environment. However, in the absence of genuine troglomorphic characters, the stygobiotic status of groundwater oligochaetes can currently be inferred only from their exclusive presence in the subterranean environment. 2. Aquatic oligochaetes constitute a diverse and mostly endemic fauna. Of the more than 100 species currently considered to be stygobionts, 60% are known only from their type locality. In the Rhone-Alpes region of France, about 93% of samples taken from caves and galleries were found to contain oligochaetes of which 13 species are classified as stygobionts. 3. Oligochaete biodiversity in aquatic subterranean environments probably originated by both preservation of relict forms and speciation in situ, possibly followed by radiations favoured by heterogeneous and fragmented habitats. Close phylogenetic affinities between some tubificid species from continental waters and the deep sea suggest a marine origin of part of the subterranean oligochaetes. 4. Oligochaetes are well known to promote bioturbation in surface habitats. Similar information on subterranean oligochaetes is scarce, but some evidence suggests notable bioturbation activity also of hypogean species, and they may also play other ecological roles (e.g. as prey and consumers) where present in high densities. 5. Valuable studies to enhance knowledge of subterranean aquatic oligochaetes include continued exploration of a variety of groundwater habitats, phylogeographic surveys that take advantage of molecular methods, analyses of species traits of both stygobiotic and epigean oligochaetes in subterranean environments, and laboratory studies to describe life histories and resolve other aspects of oligochaete biology and ecology.

This project deals with the possibility to enhance the self purification microbial activity in a stream substrates exposed to urban wet weather overflows that carry organic matter.; Le projet repose sur l'hypothèse que l'activité « autoépuratoire » en cours d'eau peut être renforcée par des formes artificielles et poreuses au travers desquelles les flux de substances liés aux flux hydriques pourraient être plus efficacement bio-assimilés. Une application particulière concerne l'environnement urbain qui modifie l'hydrologie locale et génère l'apport de matières organiques, de toxiques et d'azote, ce dernier étant considéré comme le carburant du métabolisme. L'action de recherche proposée sur une année porte sur les pré-requis géomorphologiques et hydrodynamiques auxquels un tel dispositif devrait répondre pour assurer une fonction durable, ceci en prenant en considération les contraintes physiques et chimiques de l'installation et les facteurs de la persistance et de la dynamique des populations microbiennes.

International audience

International audience; Hydrologic variability is important in sustaining a variety of ecological processes in streams and rivers. Natural flow regime classifications group streams and rivers that are relatively homogeneous with respect to flow variability and have been promoted as a method of defining units for management of river flows. Although there has been considerable interest in classifying natural flow regimes, there has been less emphasis given to developing accurate methods of extrapolating these classifications to locations without flow data. We developed a method of mapping flow regime classes using boosted regression trees (BRT) that automatically fits non-linear functions and interactions between explanatory variables of flow regimes, both of which can be expected when comparing responses between complex systems such as watersheds. A natural flow regimes classification of continental France was developed from cluster analysis of 157 hydrological indices derived from 763 gauging stations representing unmodified flows. BRT models were used to predict the likelihood of gauging stations belonging to each class based on the watershed characteristics. These models were used to extrapolate the natural flow regime classification to all segments of a national river network. The performance of the BRT models were compared with other methods of assigning locations to flow regime classes, including the use of geographically contiguous regions, linear discriminant analysis (LDA) and classification and regression trees (CART). The fitted misclassification rate (associated with model fits) for assignment based on the BRT models was 13% whereas the fitted misclassification rates for geographically contiguous regions, LDA and CART were 52%, 44% and 39%, respectively. A predictive misclassification rate (calculated for new cases) was estimated for assignments based on the BRT, LDA and CART models using cross validation analysis. For assignment based on the BRT models, the mean predictive misclassification rate was 37% whereas for LDA and CART it was 45% and 64%, respectively. Our method of mapping flow regimes could increase the confidence in decisions associated with setting environmental flows and the ability to undertake broad-scale ecohydrological research.

International audience; L'IBD 1996, normalisé AFNOR en 2000, a été l'Indice Diatomique national utilisé en routine par les Réseaux de surveillance sur le territoire français depuis les années 2000. Dans le cadre de la mise en application de la DCE sur cours d'eau, entre 2005 et 2008, les notes de cet indice ont été utilisées pour évaluer l'Etat Ecologique des cours d'eau de France, en conformité avec la trame biotypologique et la grille d'interprétation des notes contenue dans la Circulaire du 28 Juillet 2005 du Ministère chargé de l'Environnement. Une nouvelle version de l'IBD, portant sur une plus large liste d'espèces (environ 840 taxons au lieu de 213 pour la version antérieure) et conçue pour pouvoir aussi s'appuyer sur les déformations tératologiques, a été mise au point entre les années 2005 et 2007 (IBD2007, normalisé AFNOR - NF T 90-354). Son assise-taxons élargie lui permet de se comporter d'une façon stabilisée dans les différents contextes biogéographiques de France métropolitaine. Son cadre interprétatif national en matière d'Etat Ecologique a été défini dans le Guide d'Evaluation de l'Etat Ecologique diffusé au niveau national par le MEEDDAT en date du 31-03-2009. La présente communication fait un point actualisé sur ce nouvel outil et son utilisation au niveau national. Les conséquences du retrait d'un seuillage d'espèces peu abondantes sur les résultats de l'indice, intervenu lors de sa procédure de normalisation, sont évaluées. Le nouveau cadre interprétatif national sur l'Evaluation d'Etat Ecologique des cours d'eau à partir du compartiment diatomique est présenté, ainsi que les premiers résultats comparatifs entre la classification IBD 2000 et IBD 2007. Une mise en perspective des informations apportée par les diatomées par rapport à l'Etat Chimique et aux autres maillons biologiques pris en compte par la DCE est réalisée. Les étapes à venir concernant la mise en oeuvre de la DCE à l'aide du compartiment phytobenthique sont ensuite passées en revue, au niveau national comme européen.

International audience; The feeding activity and afterward the assimilation of the products resulting of the food digestion, allow organisms to obtain energy useful for growth, maintenance and reproduction. These biological parameters may be studied to assess the impact of contaminants on the energy metabolism of organisms, which could induce potential effects at an individual level. The studied species was an amphipod Gammarus fossarum, which has a high ecological relevance since it is widespread in European streams and plays a major role in the breakdown of leaf litter. Thus some G. fossarum were transplanted in four sites of a river characterized by metal contamination (Amous River, France). The following parameters were studied: digestive enzymes activities (esterase, β-glucosidase, β-galactosidase, amylase and endoglucanase), feeding rate, metal bioaccumulation and survival. Results showed a strong relationship between digestive enzymes activities, feeding rate and metal contents.

International audience; Many surface waters have been reported to be contaminated with genotoxic substances whereas the most critical sources remain to be identified. The wastewater treatment plant (WWTP) effluents discharged in surface waters is one of the significant sources. Indeed, these effluents often contain mutagens although wastewaters are treated through different processes (Ohe, 2004). Invertebrates constitute the major part of the aquatic biomass, play an essential role in ecosystems and are currently used as sentinel species in ecotoxicological studies. However, there is an obvious lack of genotoxicity biomarkers in aquatic species such as crustaceans. Recently, genotoxicity assessment has been carried out in an ecologically relevant gammarid species, Gammarus fossarum using the comet assay (see MO 182 poster). The aim of this study was to assess genotoxic stress of WWTP effluents on caged gammarids in the Ardière River, Bourbre River and Saône River.

National audience; La dégradation continue des écosystèmes aquatiques a intensifié le besoin de développer des méthodes d'évaluation de la qualité du milieu toujours plus performantes et pertinentes, basées sur la biologie et l'écologie des organismes. Dans ce contexte, l'utilisation des traits biologiques et écologiques en bio-indication fournit de nombreuses perspectives. Nous vous proposons, à travers l'exemple des diatomées et des macro-invertébrés, de voir comment sont déclinés ces traits bioécologiques en termes de bio-indication toxique.

National audience; Les biomarqueurs sont des outils mis en ½uvre pour établir un diagnostic de risque environnemental. Leurs usages et leur intérêt, notamment dans la détermination du risque de pollution, sont devenus incontournables surtout depuis que la directive cadre européenne sur l'eau a imposé la surveillance de l'état écologique des cours d'eau. Cependant, le manque de connaissances sur la biochimie, la physiologie et le comportement des organismes aquatiques sentinelles utilisés limite fortement l'utilisation optimale de ces outils. Quelles sont les connaissances disponibles sur les biomarqueurs ? Comment les utiliser et quelles sont les limites actuelles ?

National audience; Les quelques réflexions présentées font le point des connaissances sur les questions relevant de l'adaptation des espèces et de la contamination des milieux.

International audience; In 2005, the Society of Environmental Toxicology and Chemistry (SETAC) published a thorough review on Sediment Quality Guidelines (SQGs) and their uses. One of its main conclusions was that these indicators were more appropriate as benchmarks in tiered approaches to environmental quality or risk assessment than as standards in the restrictive sense of values triggering management decisions. Nevertheless, the Water Framework Directive requires environmental quality standards (EQS) also for sediments; the proposed Priority Substances directive, which currently left the issue unsolved, cannot accordingly be adopted as such. A working group (EG-EQS) has been set up by the European Commission to find a sustainable way of fulfilling the WFD requirements whilst using sound (and shared) scientific concepts. This presentation will summarise the challenges faced by the group, with focussing on organic substances. Our aim is to stimulate debate about the options being considered for setting sediment standards.

[Departement_IRSTEA]MA [TR1_IRSTEA]QSA / EXPER; International audience

International audience

International audience

International audience

[Departement_IRSTEA]MA [TR1_IRSTEA]QSA / EXPER; International audience; The parasiticide ivermectin is widely used due to its high efficiency against endo- and ectoparasites in livestock. Local aquatic ecosystems can thus be contaminated, but few data are available to quantify chronic effects of ivermectin on non-target aquatic organisms. The aim of our study is to understand how ivermectin affects survival, growth and reproduction of two cladoceran species: Daphnia magna (one Japanese and one European strain) and Ceriodaphnia dubia. Hence, chronic toxicity tests were carried out. Survival and the number of neonates per litter were daily recorded, and adult length was measured at the end of the test. The first data analyses showed that ivermectin had a significant effect on all processes, but that differences occurred between species and between strains. The European strain of D. magna was more sensitive than the Japanese one, and the effects appeared earlier but were lower for C. dubia than D. magna.

International audience

International audience

[Departement_IRSTEA]MA; International audience; It is widely accepted that evolutionary changes in conserved developmental signaling pathways play an important role in morphological evolution. However, few in silico studies were interested in tracking such changes in a signaling pathway. The Ectodysplasin (EDA) pathway provides an opportunity to fill this gap because it is involved in vertebrate skin appendage development such as scales, teeth, hair, and feathers that take an obvious part in the adaptation of species to their environment. We benefited from the large amount of genomic data now available to explore the evolution of the upstream genes of the EDA pathway. In mammals, these genes are eda (encoding 2 ligands, EDA-A1 and EDA-A2), edar (EDA-A1 receptor), edaradd (EDA receptor [EDAR] adapter), xedar (EDA-A2 receptor), and troy (a XEDAR-related receptor). We show that the evolution of EDA pathway genes combines both strongly conserved features and evolutionary shifts. These shifts are found at different signaling levels (from the ligand to intracellular signaling) and at different taxonomic levels (class, suborder, and genera). Although conserved features likely participate to the similarities found in the early development of vertebrate skin appendages, these shifts might account for innovations and specializations. Moreover, our study demonstrates that we can now benefit from the large number of sequenced vertebrate genomes to explore the evolution of specific signaling pathways and thereby to open new perspectives for developmental biology and evolutionary developmental biology.

International audience; The European Water Framework Directive (WFD) aims at implementing strategies to restore the good ecological status of water bodies. Lots of local scale studies tend to support the idea that land use along river corridors, particularly riparian vegetation, has a significant influence on the ecological status of water-bodies. Restoration of riparian zones is often seen as a key action to improve ecological status, but the actual “buffering capacity” of these systems needs to be properly estimated before to take specific buffer policy decisions. This influence has to be investigated through large scale statistical analyses between surrounding pressures close to river and ecological status indicators. The first objective of this study was to develop from remote sensing imagery an operational methodology to map long linear river corridor land use to compensate the lack of available accurate pressure information at this scale. Considering the size of these systems and the diversity of land cover, a rule-based object oriented classification using multi-source data including aerial photography (0.5 m) and SPOT 5 XS (10 m), was implemented. Land use on riparian buffers has been classified with a good accuracy on the whole hydrographic network (about 2000 Km) of Herault watershed in the south of France. The second objective was to define and compute a set of synthetic spatial indicators of the river corridor land cover that can be linked to the ecological status of rivers. Such indicators are representative of both riparian zone functions and alteration processes. Spatial structure of riverscape is finely resolved and riparian vegetation information is reliably quantified and spatialized. To assess our approach, several spatial indicators, computed from resulting classifications and Corine Land Cover database, have been compared. Results of this study highlight the need for VHRS imagery for accurate quantification of the extent, configuration, and properties of land cover in the riparian buffer zone. The next step will be to test the functional link between biological assemblage and these spatial indicators across large scale.

International audience; The Tribolium genome contains 21 nuclear receptors, representing all of the six known subfamilies. When compared to other species, this first complete set for a Coleoptera reveals a strong conservation of the number and identity of nuclear receptors in holometabolous insects. Two novelties are observed: the atypical NR0 gene knirps is present only in brachyceran flies, while the NR2E6 gene is found only in Tribolium and in Apis. Using a quantitative analysis of the evolutionary rate, we discovered that nuclear receptors could be divided into two groups. In one group of 13 proteins, the rates follow the trend of the Mecopterida genome-wide acceleration. In a second group of five nuclear receptors, all acting together at the top of the ecdysone cascade, we observed an overacceleration of the evolutionary rate during the early divergence of Mecopterida. We thus extended our analysis to the twelve classic ecdysone transcriptional regulators and found that six of them (ECR, USP, HR3, E75, HR4 and Kr-h1) underwent an overacceleration at the base of the Mecopterida lineage. By contrast, E74, E93, BR, HR39, FTZ-F1 and E78 do not show this divergence. We suggest that coevolution occurred within a network of regulators that control the ecdysone cascade. The advent of Tribolium as a powerful model should allow a better understanding of this evolution.

Physiological and behavioural responses of the acid-sensitive amphipod Gammarus pulex exposed to a wide range of acid conditions (pH 4.1, 5.1, 6.0) under laboratory conditions were investigated. An exposure of 38 h to acid conditions caused significant decreases in survival rate, osmolality, haemolymph Na+ concentration, ventilatory and locomotor activity compared to organisms exposed to a circumneutral medium (pH 7.9). We highlighted the interest of using individual response distribution, since drastic effects can be detected in organisms exposed to pH 6.0, in particular for osmolality: The response can be divided into two groups, unimpacted and impacted organisms. Moreover this representation permitted to evaluate the health level of individual organisms through the determination of threshold values. Significant correlations between mean pH and mean physiological/behavioural responses were observed. The relationships between individual responses permitted not only to compare endpoints, but also to show that affected organisms were impacted by ionoregulation failure, hypoventilation and low locomotor activity. The energetic reallocation in favour of maintenance functions, such as osmoregulation, is discussed. The results of this study indicate that the values of haemolymph Na+ concentration, osmolality and locomotor activity in G. pulex could be effective ecophysiological/behavioural markers to monitor freshwater ecosystems and to assess the health of organisms or populations.

The aim of this study was to investigate the effects of cadmium on physiological and behavioural responses in Gammarus pulex. In a first experiment, cadmium LC50s for different times were evaluated in 264 h experiment under continuous mode of exposure (LC50(96 h)=82.1 microgL(-1), LC50(120 h)=37.1 microgL(-1), LC50(168 h)=21.6 microgL(-1), LC50(264 h)=10.5 microgL(-1)). In a second experiment, the physiological and behavioural responses of the amphipod exposed to cadmium (0, 7.5 and 15 microgL(-1)) were investigated under laboratory conditions. The mortality and the whole body cadmium concentration of organisms exposed to cadmium were significantly higher than in controls. Concerning physiological responses, cadmium exposure exerted a significant decrease on osmolality and haemolymph Ca(2+) concentration, but not on haemolymph Na(+) and Cl(-) concentrations, whereas the Na(+)/K(+)-ATPase activity was significantly increased. Behavioural responses, such as feeding rate, locomotor and ventilatory activities, were significantly reduced in Cd exposed organisms. Mechanism of cadmium action and consequent energetic reallocation in favour of maintenance functions (i.e., osmoregulation) are discussed. The results of this study indicate that osmolality and locomotor activity in G. pulex could be effective ecophysiological/behavioural markers to monitor freshwater ecosystem and to assess the health of organisms.

The availability and bioaccumulation of metals and metalloids, and the geochemical interactions among them, are essential to developing an ecological risk assessment (ERA) framework and determining threshold concentrations for these elements. The purpose of this study was to explore the relationships among total recoverable and reactive metals and metalloid in sediment and their bioaccumulation by chironomids. In the fall of 2004 and 2005, 58 stations located in the three fluvial lakes of the St. Lawrence River and its largest harbour area in Montreal, Canada, were sampled. Nine total recoverable and reactive metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) and one metalloid (As) were measured in whole sediment using two extraction methods: HCl/HNO 3 and HCl 1N, respectively. The bioaccumulation of six metals (Cd, Cr, Cu, Ni, Pb and Zn) and As by chironomids was evaluated in a subset of 22 stations. Strong collinearities were observed between some total recoverable or reactive metal concentrations in sediment; two principal clusters, including collinear metals, were obtained. The first one included metals of mainly geological origin (Al, Cr, Fe, Mn, Ni), while the second one included As, Cd, Cu, Pb and Zn, which likely derive mainly from point sources of anthropogenic contamination. Each element also showed strong collinearity between their total recoverable and reactive forms (0.65 ≤ r ≤ 0.97). We can conclude that both chemical forms are equivalent for use in statistical models needed to explain biological responses and also in screening risk assessment. However, these relationships are not always proportional. Lower availability percentages were observed for Cd, Cu and Zn in the highly mixed-contaminated area of the Montreal Harbour, even though concentrations in sediment were higher. We observed a significant correlation (0.50 ≤ r ≤ 0.56) between concentrations in chironomids and concentrations of both total recoverable and reactive Cr and Pb in sediment. Arsenic was an exception, with accumulation by chironomids being highly related to reactive sediment concentrations. Finally, we observed variable influences of explanatory factors (e.g. sediment grain size, Al, Fe, Mn, S, TOC), depending on which metal or metalloid was being predicted in chironomids. In this context, it is difficult to choose a universal predictive method to explain the bioaccumulation of specific metals, and more research is still needed into normalization procedures that consider a combination of explanatory factors.

International audience; In landscape ecology, landscapes are viewed as hierarchically-organized groups of interacting components or zones. This perspective is applied in studies of riverscapes with increasing frequency, particularly in studies of channel habitats and channel-fl oodplain interactions. Stygoscapes, the subsurface portions of riverscapes, have received less attention. Stygoscapes are composed of three saturated zones beneath and lateral to river channels: the hyporheic, parafluvial and riparian zones. These zones are differentiated on the basis of hydrological, biological and chemical conditions, and the degree of interaction with the channel surface. In this paper, we describe lateral and longitudinal patterns in the shallow (30 cm 10 m depth) stygoscape of the alluvial Selwyn River, New Zealand. We used abutting hyporheic, parafl uvial and riparian zones in large-scale downwelling (losing) and upwelling (gaining) sections of the river mainstem to compare physico-chemical and biological conditions across a broad stygoscape. The stygoscape zones had the same arrangement in both sections: hyporheic zones within the wetted channel, riparian zones furthest from the channel, and parafl uvial zones between the hyporheic and riparian zones. Nitrate and dissolved reactive phosphorus concentrations and electrical conductivity were signifi cantly higher, and dissolved organic phosphorus concentrations and pH levels lower, in the gaining section than the losing section. In both sections, ammonium, dissolved reactive phosphorus, and dissolved organic carbon concentrations and pH were higher in the hyporheic zone than the riparian zone. Within the losing section, DON and DOP concentrations were higher in the hyporheic zone than the riparian zone. Physico-chemical conditions were intermediate in the parafl uvial zones of both river sections. These among-zone differences suggest that hyporheic zones are sinks for dissolved nutrients, and that effects of hyporheic sinks are greatest in losing river sections with unidirectional flow from the surface to the hyporheic zone. There were large differences among stygoscape zones in invertebrate assemblage composition, and smaller differences between the losing and gaining sections. Invertebrate densities, taxon richness and % insect taxa were higher in hyporheic zones than riparian zones. Invertebrate densities were intermediate in the parafl uvial zones, and taxon richness and % insect taxa were similar in parafl uvial and riparian zones. The spatial patterns we observed in the Selwyn River suggest that hydrological connectivity between zones, and permeability within zones, are among the most important determinants of chemical and biological dynamics in stygoscapes. Differences in large-scale upwelling and downwelling, and differences in water source (runoff and groundwater) appeared to be of secondary importance.

International audience; Physiological and behavioural responses of the acid-sensitive amphipod Gammarus pulex exposed to a wide range of acid conditions (pH 4.1, 5.1, 6.0) under laboratory conditions were investigated. An exposure of 38h to acid conditions caused significant decreases in survival rate, osmolality, haemolymph Na+ concentration, ventilatory and locomotor activity compared to organisms exposed to a circumneutral medium (pH 7.9). We highlighted the interest of using individual response distribution, since drastic effects can be detected in organisms exposed to pH 6.0, in particular for osmolality: the response can be divided into two groups, unimpacted and impacted organisms. Moreover this representation permitted to evaluate the health level of individual organisms through the determination of threshold values. Significant correlations between mean pH and mean physiological/behavioural responses were observed. The relationships between individual responses permitted not only to compare endpoints, but also to show that affected organisms were impacted by ionoregulation failure, hypoventilation and low locomotor activity. The energetic reallocation in favour of maintenance functions, such as osmoregulation, is discussed. The results of this study indicate that the values of haemolymph Na+ concentration, osmolality and locomotor activity in G. pulex could be effective ecophysiological/behavioural markers to monitor freshwater ecosystems and to assess the health of organisms or populations.

Le 4ème workshop NORMAN, le dernier des workshops thématiques proposé dans le cadre du projet européen NORMAN (6ème PCRD, coordination INERIS), a réuni à Lyon les 17 et 18 mars 2008 une centaine de chercheurs et gestionnaires venus de toute l'Europe et au delà (France, Espagne, Norvège, Allemagne, Pays-Bas, U.K., Etats-Unis ). Ce workshop a permis des échanges nourris autour des nouvelles approches de surveillance des milieux aquatiques (eau douce et eau marine). Il a focalisé l'attention des chercheurs sur les besoins de développement de la recherche et d'échange de données afin de mieux répondre aux défis que représentent la surveillance et l'évaluation du risque des substances émergentes dans le cadre des directives européennes. Ce rapport présente une synthèse de chacune des trois thématiques et les discussions abordées au workshop ainsi que les contributions du projet NORMAN.

National audience; La dégradation continue des écosystèmes aquatiques a intensifié le besoin de développer des méthodes d'évaluation de la qualité du milieu toujours plus performantes et pertinentes, basées sur la biologie et l'écologie des organismes. Dans ce contexte, l'utilisation des traits biologiques et écologiques en bio-indication fournit de nombreuses perspectives. Nous vous proposons, à travers l'exemple des diatomées et des macro-invertébrés, de voir comment sont déclinés ces traits bioécologiques en termes de bio-indication toxique.

International audience; The need for protecting or rehabilitating aquatic habitats in urban areas and the need for incorporating such management actions into urban water management have been briefly introduced in Chapter 1. The main purpose of this chapter is to further develop the urban aquatic habitats description, with respect to their basic characteristics and functioning, and set the stage for further discussions of their management in the following chapters. Understanding the habitat characteristics that affect aquatic biological communities, as weil as the functioning of the aquatic ecosystem, helps to set realistic objectives for the protection or rehabilitation of its ecological status or potential and set implications for management actions. Various aspects of aquatic habitat protection and rehabilitation and their integration with urban water management with respect ta strategies, planning and technical measures are addressed later on in this book.

[Departement_IRSTEA]MA [TR1_IRSTEA]QSA / EXPER; International audience; We report the strategy adopted for the modeling of a resident brown trout population living in a theoretical river network. We consider chronic cadmium pollution occurring in one stretch of river. Using RAMAS Metapop, spatial modeling allows us to integrate spatial heterogeneity influencing the population dynamics and also influenced by the heterogeneity of the environmental contamination. We show how to perform the assessment of global impact of pollution from local perturbations using this modeling step: we build for instance population level dose-response curves linking population features with pollutant concentrations. We take advantage of the flexibility of RAMAS Metapop to deal with demographic stochasticity in order to discuss the use of deterministic models or stochastic models (extinction risk concepts) to provide population endpoints for decision-making. Besides, we confirm the conclusion of a previous contribution focused on the potential effect of migratory disruptions due to pollution: random variations in the dispersal pattern during the breeding event expand the extinction risk of the trout population. So increasing efforts are necessary to develop knowledge relative to toxicant-induced spatial behaviors and to integrate such effects in the definition of environmental quality criteria.

International audience; Tribolium castaneum is a member of the most species-rich eukaryotic order, a powerful model organism for the study of generalized insect development, and an important pest of stored agricultural products. We describe its genome sequence here. This omnivorous beetle has evolved the ability to interact with a diverse chemical environment, as shown by large expansions in odorant and gustatory receptors, as well as P450 and other detoxification enzymes. Development in Tribolium is more representative of other insects than is Drosophila, a fact reflected in gene content and function. For example, Tribolium has retained more ancestral genes involved in cellcell communication than Drosophila, some being expressed in the growth zone crucial for axial elongation in short-germ development. Systemic RNA interference in T. castaneum functions differently from that in Caenorhabditis elegans, but nevertheless offers similar power for the elucidation of gene function and identification of targets for selective insect control.

Le travail présenté ici se développe sur le bassin périurbain de l'Yzeron, (150 km2), situé dans l'Ouest lyonnais. Il présente un net gradient d'urbanisation de l'amont vers l'aval. Entre les années 70 et 90, il est passé de 6 à 19% d'urbanisation essentiellement sur la partie aval du bassin ; l'amont ayant connu une mutation d'une autre nature : les cultures cédant la place aux prairies, aux friches et enfin à la forêt. L'expansion urbaine se traduit donc par une artificialisation du paysage et par l'abandon de l'exploitation des terres de la deuxième couronne. Le Grand Lyon tente de limiter la dégradation de la qualité de l'eau par les rejets urbains par temps de pluie (RUTP), et les processus d'incision et d'ensablement. L'insuffisance avérée du réseau actuel, et a fortiori dans le futur, amène le Grand Lyon à étudier son adaptation vis-à-vis de la loi sur l'Eau en termes de taux de collecte et de nombre de rejets par an. La connaissance des mécanismes de l'impact des rejets et des mécanismes d'assimilation par le milieu rivière est un des critères de choix de solutions et de modes de gestion des RUTP. La dimension paysagère et sociologique de ces choix est prise en compte. L'ambition de ces recherches s'inscrit donc selon deux axes : le développement du diagnostic d'impact des RUPT sur les rivières périurbaines et la compréhension de l'évolution des processus en fonction de l'accroissement urbain ; cela afin de proposer des solutions de gestion de l'espace péri-urbain moins dommageables pour le milieu aquatique. Le paradigme "flux-formes-biocénoses" développé permet d'identifier des modes d'assimilation différents des flux de nutriments et de polluants. Cette assimilation montre des dynamiques plus ou moins rapides dans l'espace et dans le temps. On note ainsi une évolution saisonnière sur le site expérimental et la rivière Yzeron, liée aux contextes hydrologiques naturel et urbain ainsi qu'une alternance longitudinale de la qualité du cours d'eau. Ces propriétés spatiales et temporelles couplées à une cartographie selon une typologie géomorphologique pourraient s'avérer être un véritable instrument de gestion des RUTP. Un inventaire cartographique des incisions des cours d'eau de tête de bassin versant est actuellement en cours de réalisation. Le rôle des acteurs locaux et des politiques d'aménagement devra être intégré à l'analyse globale. Ainsi une typologie des valeurs et des attitudes des habitants des berges face à la rivière de l'Yzeron, basée sur des indicateurs de sensibilité, de besoins de la collectivité et des objectifs des décideurs, permettra d'aborder les freins structurels d'une politique intégrant dynamique de la rivière et services rendus.

International audience; The objectives of the workshop are to share experiences between Austria and France on issues related to management of potential social, economical and environ mental impacts of hydropower dams in the context of implementing the EU Water Framework Directive and global change. The workshop will bring together scientists, policy-makers and managers, NGOs, in order to share the results of current research activities and identify research priorities for the future.

International audience; The main objective of the Water Framework Directive (WFD) is to reach a good ecological status in all rivers and watersheds by 2015. The health of fish communities is considered to be one of the main environmental indicators to evaluate the status of a river. Lessons have been learned from the impacts of the 2003 heat wave, and a working group in hydrobiology and temperature has been created in France. One of the goals is the exploitation of long-term data (> 20 years) from biological monitoring programs set up in the vicinity of all French nuclear power stations. An initial meta-analysis assessing the effect of climate change on stream organisms was presented in 2005. The fish communities in French rivers, subject to various anthropogenic pressures, globally showed long-term changes that have paralleled the progressive rise in water temperature (+0.5 to +1.6 °C over the last ten years), consistent with the predicted effects of climate warming. This study provides evidence that the effects of climate change should not be ignored when analyzing long-term changes in community structures, even in highly disturbed sites. The authors also propose the questions and components for establishing a new research agenda, to make optimum use of the knowledge gained in the 70s and to build up new knowledge.

International audience; Mapped environmental classifications are defined using various procedures but there has been little evaluation of the differences in their ability to discriminate variation in independent ecological characteristics. We tested the performance of environmental classifications of the streams and rivers of France that had been defined from the same environmental data using geographic regionalization and numerical classification of individual river valley segments. Test data comprised invertebrate assemblages, water chemistry and hydrological indices obtained from sites throughout France. Classification performance was measured by analysis of similarity (ANOSIM). Geometric regions defined by a regular grid and without regard to environmental variables and a posteriori classifications based on clustering the test datasets, defined lower and upper bounds of performance for a given number of classes. Differences in classification performances were generally small. The ANOSIM statistics for the a posteriori classifications were around twice that of all environmental classifications, including geometrically defined regions. The hydro-ecoregions performed slightly better for the invertebrate data and the network classification performed slightly better for the chemistry and hydrological data. Our results indicate that environmental classifications that are defined using different procedures can be comparable in terms of their ability to discriminate variation of ecological characteristics and that alleged differences in performance arising from different classification procedures can be small relative to unexplained variation. We conclude that definition procedures may have little effect on the performance of large-scale environmental classifications and decisions over which procedures to use should be based primarily on pragmatic considerations.; Etude de performance des classifications de réseau par rapport aux Hydro Ecoregions (HER). Cette étude a montré que les HER sont aussi performantes qu'une classification de réseau, mais ces deux classifications ne sont pas plus performantes qu'une grille carrée.

International audience; A hydroelectric power plant (HPP) started operation in December 2002 on the River Lhomme, (mean annual flow: 1.78 m3 s−1; mean annual water temperature: 9.9°C). The new HPP bypasses the river over a length of 1.2 km. The minimum flow allowed in the bypassed section is currently fixed at 0.220 m3 s−1. Before the construction of the HPP, two contrasted 150-m-long reaches of the Lhomme were selected to estimate their total fish population abundance and to analyse their fish population dynamics. Electrofishing was carried out in each of these two reaches on 23 April 2002 in a natural flow situation to remove the fish. Other inventories were carried out in late April or early May in 2003, 2004, 2005 and 2006 in minimum flow conditions. The results revealed a prompt and severe decrease in the total fish biomass (up to 81% for grayling from 2002 to 2006) combined with severe changes in the fish community structure that were not observed in a reference site. The effects of the flow reduction varied considerably depending on the size of the individuals, the species concerned and their habitat availability, which was modelled using a classical physical habitat simulation (EVHA method).

Avant toute chose, je crois nécessaire de replacer le contexte de mes activités de chercheur à la fois au sein de l'organisme où j'ai réalisé ma carrière, mais également dans le cadre du domaine où j'ai travaillé, l'écotoxicologie. Après une formation en Sciences et Techniques de l'Eau à la faculté des Science de Montpellier (USTL) dans laquelle étaient étroitement associées des formations en chimie et en biologie, j'ai obtenu en 1980 un doctorat en Ecotoxicologie et Chimie de l'Environnement, de l'Université de Metz, sous la direction du Pr. Jean Michel Jouany. Ce travail de recherche sur l'impact des rejets des centrale thermiques sur les organismes aquatiques, a confirmé mon intérêt dans une recherche en étroite interaction avec les questions pratiques de gestion environnementale. J'ai ensuite été recrutée comme ingénieur d'étude en 1981 au CETEGREF, qui deviendra quelques années plus tard seulement, le Cemagref, assorti d'un statut d'Etablissement Public Scientifique et Technologique. Lors de mon recrutement, avec la responsabilité du laboratoire, j'ai eu pour mission le développement des activités en écotoxicologie à Lyon, et ce pour répondre aux besoins des acteurs, industriels publics ou privés et gestionnaires du domaine de l'eau (EDF, Agences de l'Eau , Ministère de l'Environnement3). Dans les années 90, la transformation de l'établissement en EPST s'est naturellement accompagnée d'un développement des missions de recherche et d'un renforcement des collaborations avec les laboratoires universitaires et d'autres EPST. J'ai ainsi eu l'occasion, sinon la chance, d'exercer relativement tôt dans ma carrière une responsabilité d'animation d'études et de recherches, au sein d'une petite équipe d'ingénieurs et techniciens (3 personnes). Cette équipe s'est enrichie avec le temps, d'ingénieurs du ministère de l'agriculture, qui pour certains ont consacré sous ma direction quelques années de leurs activités de recherche au laboratoire4, et plus récemment de jeunes chercheurs titulaires. Cette mission de recherche, que je mène aujourd'hui au sein d'un Thème de Recherche5 du département Milieux Aquatiques, est, pour ce qui me concerne, clairement en étroite relation avec des questions concrètes d'appui à la gestion des écosystèmes d'eau douce. Elle est cohérente avec des recherches en écotoxicologie, discipline centrée sur les interactions toxiquebiote, adossée aux domaines de la biologie, de la chimie et de la toxicologie, et qui doit contribuer à apporter à l'écologie des concepts et des méthodes utiles à la mise en ½uvre de programmes de restauration des milieux, au bénéfice des écosystèmes et de l'homme qui les exploite. J'ai exploré divers champs de l'écotoxicologie, côté chimie et côté biologie, et ce pour répondre sur des bases scientifiques aux interrogations de la sphère publique, non seulement pour produire des connaissances sur les interactions substances chimiques-biote, mais également des outils de mesure et d'évaluation appropriés à la gestion de l'environnement, au profit d'une plus grande durabilité des ressources aquatiques; et l'on s'arrêtera pour ce qui est des exemples, aux sources les plus actuelles des questions récurrentes sur ces interactions chimie-environnement, comme le programme de l'Union Européenne d'enregistrement, d'évaluation et autorisation des substances chimiques (REACH, 2006) et la Directive Cadre européenne sur l'Eau (2000) qui conduiront pour de nombreuses années encore les questions de recherche en écotoxicologie, auxquelles s'ajoute une nouvelle composante sur les interactions avec la santé humaine avec la mise en ½uvre du Plan National Santé Environnement (2004) mais ce sera un autre débat ! Aussi, la variété de mes activités de recherche, source possible de critiques à l'aune de la rigueur disciplinaire, est néanmoins un reflet des nuisances qui accompagnent l'ingéniosité humaine, sur l'impact desquelles j'ai été interrogée tout au long de ma carrière, et auxquelles je me suis efforcée de répondre, avec un effort croissant d'une meilleure prise en compte d'une « nuance » de complexité des écosystèmes ; mais le fil rouge demeure bien toujours le toxique dans tous ses effets ! Enfin, cette variété, c'est aussi le moteur d'un enthousiasme renouvelé pour conduire équipe et travaux dans un domaine souvent interrogé sinon critiqué (Banks et Stark 1998 ; Steinberg and Ade 2005), à l'interface entre recherche et ingénierie, et qui pour cette raison cherche encore une place respectée et durable au sein de communautés plus monodisciplinaires.

Ce rapport présente les résultats des relevés de température de l'eau du Rhône effectués au cours de l'été 2008 par le Cemagref de Lyon (Bely-Dynam) entre l'amont et l'aval du CNPE de Bugey. Ces relevés ont été effectués selon les préconisations du groupe de travail GT1-Medad en vue d'obtenir des mesures complémentaires de température de l'eau du Rhône autour du CNPE de Bugey. Ces mesures viennent compléter les suivis classiques annualisés, et les suivis particuliers à mettre en place en cas de mise en ½uvre de l'arrêté canicule. Les objectifs de l'étude étaient (1) de définir un protocole simple à mettre en ½uvre tout en garantissant des mesures fiables, (2) de caractériser au mieux le mélange des veines d'eau chaude (rejet principal du CNPE) et d'eau froide (Rhône), et donc l'emprise spatiale de chacune des deux veines d'eau ; (3) d'évaluer l'importance de la stratification verticale de la température de l'eau, et (4) d'évaluer la pertinence des informations fournies par des mesures de profils de température et par des enregistrements en continu (pas de temps horaire) de la température en des points fixes. Il semble raisonnable de poser comme hypothèse qu'aucune stratification thermique verticale (i.e. dans la colonne d'eau) n'est à considérer dans le Rhône à Bugey. En amont du CNPE l'ensemble de la masse d'eau est très homogène ; tant sur la verticale qu'entre la rive droite et la rive gauche. La stratification thermique transversale est très fortement marquée à la sortie du rejet avec une différence de 8°C en quelques mètres. Ensuite, jusqu'en amont de la confluence de l'Ain, la veine d'eau réchauffée (relativement à la température amont du CNPE) est beaucoup plus large (plus de la moitié du chenal) et la différence de température entre rive droite et rive gauche est beaucoup plus graduelle. Cette différence de température entre la rive droite et la rive gauche est encore de 1°C juste avant la confluence avec l'Ain. Entre le CNPE et l'aval de la confluence de l'Ain, la température de l'eau augmente d'environ 1.3°C à 2°C. Enfin, la méthode d'échantillonnage mise au point peut être considérée comme reproductible.

The minimum flow is an important aspect of the flow regime. Increasing the minimum flow of the by-passed sections of the Rhône river favours midstream species that are importrant for the regional biodiversity. These effects are partly predictible but have to be studied on the long-term because they can be coufounded with other effects., Le débit minimum est un des aspects importants du régime hydrologique. Son augmentation dans les vieux Rhône. Son augmentation dans les vieux Rhône favorise les espèces typiques des grands fleuves et la biodiversité régionale. Ces effets sont en partie prévisibles, mais ils s'inscrivent dans un contexte de changements multiples. Leur étude nécessite un effort de suivi écologique du fleuve général et pérenne.

International audience; Methods for defining and retrieving reference conditions for large rivers were explored with emphasis on hydromorphologic and biologic quality indicators. For a set of four large rivers in the European Western Plains ecoregion, i.e., the rivers Meuse, Loire, Allier, and Dordogne, reference reaches were selected based on geomorphologic characteristics. A survey of riparian land use, vegetation, and bed geometry was done for the selected reaches. Responses of the riparian landscape to hydromorphologic conditions were determined with a set of existing and newly developed measures of riparian dynamics and forest development. Strong correlations were observed at the reach and local levels between the ratios of width to depth and embankment and the developed measures of riparian dynamics and forest. Boundary conditions for riparian forest development were determined for the hydromorphologic and biologic indicators of riparian dynamics and vegetation structure. These conditions also proved useful for determining the presence of sustainable populations of Populus nigra and Salix purpurea. From this agreement between abiotic and biotic boundary conditions, a set of useful reference conditions was determined, and a framework for the definition of reference and good status conditions subsequently evolved. Finally, a proposal for assessment and monitoring the proposed indicators is discussed for its applicability.

International audience; Stream bio-assimilation capacity is assessed in a developing peri-urban area on the west side of Lyon, France. The total population of Lyon is 1.6 million (2000) and the climate is mild continental with Mediterranean influences. Perennial and intermittent small streams with porous sediment beds and high stormwater and groundwater exchange capacity represent ecosystems very sensitive to pollution. Threats include poor water quality, physical habitat degradation and flood hazard. This study's objective is to adapt Combined Sewer Overflows (CSOs) to the bio-assimilation capacity of the receiving streams (see Figure 9.8). Major actions consist of identifying factors that control bio-assimilation capacity, and exploitating the enhancement of these factors for improving the state of water resources in the catchment.

International audience; Regulatory assessments of metal toxicity on freshwater organisms assume that toxic effects are caused by dissolved metals. In aquatic systems, organisms are exposed to both dissolved and particulate-bound metals. In this study, the chronic toxicity of dietary Cd on the reproduction and Cd body burden of Daphnia magna was investigated. Daphnids (< 24 h) were successively exposed to dissolved Cd (8 h) and then to uncontaminated or contaminated algae (16 h) for 21 days. Results show a higher Cd burden of daphnia due to contaminated food addition and show that Cd uptakes by D. magna from water and food were additive for the lowest Cd concentrations tested. Similar Cd distributions (cytosolic and insoluble fractions) were observed in the two groups of organisms, showing similar potential toxicity of Cd accumulated from the two exposure routes. Dietary Cd induces deleterious effects on D. magna reproduction. Based on Cd body burden of daphnids, results supports the claim that waterborne and dietary Cd exposures were additive in causing toxicity for Cd concentration lower than 25 µg.L-1. At the highest Cd concentrations, the importance of dietary Cd on daphnids contamination level decrease and confounding factors such as feeding rate reduction seem appear, allowing to induce an impact on neonate reproduction. This study illustrates the need to take the dietary pathway into account in regulatory assessments and to establish effective concentrations with particulate-bound metals.