Search

International audience; L'évaluation écologique des très grands cours d'eau au sens de la Directive européenne sur l'eau reste encore un challenge. La réflexion menée entre Etats-membres permet de définir des principes méthodologiques, mais la diversité de ces écosystèmes rend une approche globale peu pertinente. Cette communication propose une vision d'ensemble et un état d'avancement des réflexions et des méthodes mises en ½uvre en France, dans ce contexte méthodologique européen.

International audience; Taking the nested scales of stream functioning into account in analysing the links between pressures and ecological status calls for the development of hierarchical models on the monitoring datasets. We aimed at answering the following questions: Does the indirect links between pressures and ecological status modify the classically observed impact hierarchy of pressures? Do the different nested scales play a different role in the pressures-ecological status relationship? Do hydromorphological alterations play a specific role in ecological status evaluation? To achieve that goal, we used the PLS path modelling method to develop a structural model linking latent variables built on (i) land use, and hydromorphological pressures descriptors at watershed scale, (ii) hydromorphological alterations assessed at reach scale, (ii) nutrients-organic matter contamination levels, and (iv) substrate samples to explain the score variation in the French monitoring macroinvertebrate based indicator I2M2. This method allows one to express the total effect of a variable as the sum of its direct and indirect effects. As a first important result, we have highlighted the importance of land use effect exerted on both hydromorphology and physico-chemistry and their translation as an indirect effect on biological condition of streams. We have also demonstrated that hydromorphological alterations had an effect on substrates structure and nutrients and organic matter concentrations. This study also reveals that hydromorphology has a major effect on macroinvertebrates indicator, thus indirect. Comparatively, nutrients and organic matter total effect on macroinvertebrates communities appears lower than expected since we take into account all the indirect effects of land use and hydromorphological alterations.

International audience; Benthic diatoms are widely used over the world to assess the quality of freshwater ecosystems. Their taxonomic diversity, life-history trait variety and ability to respond fastly to water quality degradation make them efficient ecological indicators. Even if diatom-based biotic indices are valuable tools in detecting the degradation/restoration of aquatic ecosystems, they do not clearly help to identify the nature of pressure(s) impairing in situ communities. In this context, we aimed at developing a diatom trait based tool that helps to estimate the probability that a specific pressure significantly impairs local communities. autecological information on various traits (biovolumes, life forms…) was gathered from literature and expert advices for species caught in > 1500 sampling sites of the French RCS national river survey. Most of this information was fuzzy-coded to take into account within-species variation in life-history characteristics. The responses of metrics were assessed for several pressure categories related to water chemistry (e.g. herbicides, acidification) and habitat degradation, in an ecoregional framework. For each pressure category a Condition Tree Forest model was built using the risk level as the response variable and the trait-based metrics as the predictive variables. This work contributes to the development of a multi biological-quality-element based diagnostic tool.

International audience; To achieve a good ecological status for all water bodies in time, the Water Framework Directive raises serious problems for political decision-makers and water managers who adress many questions for aquatic scientists. During the last ten years, most of the research works carried out within the scope of the WFD was dedicated to development of bioassessment tools based on different biological quality elements (algae, benthic fauna and fish), using data from national monitoring networks. However, not all water bodies are surveyed across France, due to both technical limitations and economic reasons. Within this context, it is therefore very important to strengthen the direct monitoring of water bodies to develop efficient methods for the classification of non-monitored water bodies based on robust and homogeneous predictive models based on causal relationship between biological quality elements (and consequently ecological status) and multiple impairments and stressors at catchment and local scales. We developed a model for the classification of non-monitored water bodies. This model is based on land cover, water quality and hydromorphological pressures and allow to make a spatial extrapolation of ecological status at the scale of water bodies. It is developed using classification and regression tree method and have a very good predictive efficiency. We complete this extrapolation model with other models (using partial least square regression methods) aiming to make the diagnostic of pressures responsible for bad status of water bodies. These models explain benthic invertebrates, diatoms and fish index using land cover, water quality and hydromorphological pressures and allow to assess the relative impact of each type of pressure and the response of each biological quality element. The development of such a pressures/impact models is a very promising alternative to compensate the availability of local monitoring data. Even if these models are of course not able to solve all water manager's problems, they may help them to optimize monitoring programs and to assign an ecological status to those water bodies which are not surveyed, based on the pressures acting at a local and/or regional scales and the statistical relationships established for surveyed sites located in the same pressures context.

International audience; To achieve a good ecological status for all water bodies in time, the Water Framework Directive raises serious problems for political decision-makers and water managers who adress many questions for aquatic scientists. During the last ten years, most of the research works carried out within the scope of the WFD was dedicated to development of bioassessment tools based on different biological quality elements (algae, benthic fauna and fish), using data from national monitoring networks. However, not all water bodies are surveyed across France, due to both technical limitations and economic reasons. Within this context, it is therefore very important to strengthen the direct monitoring of water bodies to develop efficient methods for the classification of non-monitored water bodies based on robust and homogeneous predictive models based on causal relationship between biological quality elements (and consequently ecological status) and multiple impairments and stressors at catchment and local scales. We developed a model for the classification of non-monitored water bodies. This model is based on land cover, water quality and hydromorphological pressures and allow to make a spatial extrapolation of ecological status at the scale of water bodies. It is developed using classification and regression tree method and have a very good predictive efficiency. We complete this extrapolation model with other models (using partial least square regression methods) aiming to make the diagnostic of pressures responsible for bad status of water bodies. These models explain benthic invertebrates, diatoms and fish index using land cover, water quality and hydromorphological pressures and allow to assess the relative impact of each type of pressure and the response of each biological quality element. The development of such a pressures/impact models is a very promising alternative to compensate the availability of local monitoring data. Even if these models are of course not able to solve all water manager's problems, they may help them to optimize monitoring programs and to assign an ecological status to those water bodies which are not surveyed, based on the pressures acting at a local and/or regional scales and the statistical relationships established for surveyed sites located in the same pressures context.

International audience

International audience

Suite à l'application de la Directive Cadre sur l’Eau (DCE), dont la ligne directrice est le besoin d’un suivi de la qualité écologique des cours d’eau, et au besoin de méthodes de bioévaluation plus performantes, l’université de Lorraine a développé un nouvel indice pour les invertébrés benthiques, l’Indice Invertébrés Multi-Métrique (I2M2). Cet indice sera opérationnel à partir du prochain cycle de gestion, en 2016, et remplacera l’indice actuel, l'IBGN.

Suite à l'application de la Directive Cadre sur l’Eau (DCE), dont la ligne directrice est le besoin d’un suivi de la qualité écologique des cours d’eau, et au besoin de méthodes de bioévaluation plus performantes, l’université de Lorraine a développé un nouvel indice pour les invertébrés benthiques, l’Indice Invertébrés Multi-Métrique (I2M2). Cet indice sera opérationnel à partir du prochain cycle de gestion, en 2016, et remplacera l’indice actuel, l'IBGN.

International audience; How macroinvertebrate respond to human disturbances can be characterized following two major approaches. The traditional taxonomic approach has been extensively used. Since the nineties, another approach based on functional traits has experienced and offer a better understanding of community-environment relationships and functioning of ecosystems facing human impacts. In this study, we assessed sediment quality in a large river in North America by exploring the relationships between chemical contamination and benthic community structure using the functional trait approach. This study was carried out in the St-Lawrence River, an essential waterway exposed to many anthropogenic stresses such as industrial and municipal wastewater or agricultural activities. Macroinvertebrates were collected in 59 sites. Organic, inorganic contaminants and sediments characteristics (grain size, organic matter, nutrient, etc) were measured in the whole sediment. Seventeen biological or ecological traits of taxa were coded, taking into account regional climate and ecosystem specificities. The goals of this study were: (1) to describe spatial patterns in functional traits of macroinvertebrate communities; (2) to determine relationships between trait combinations and taxonomic structure and (3) to link macroinvertebrate assemblages and trait combinations to environmental conditions and sediment quality.

International audience; How macroinvertebrate respond to human disturbances can be characterized following two major approaches. The traditional taxonomic approach has been extensively used. Since the nineties, another approach based on functional traits has been experiment and offer a better understanding of community-environment relationships and functioning of ecosystems facing human impacts. In this study, we assessed sediment quality in a large river in North America by exploring the relationships between chemical contamination and benthic community structure using the functional trait approach. This study was carried out in the St-Lawrence River, an essential waterway exposed to many anthropogenic stresses such as industrial and municipal wastewater or agricultural activities. Macroinvertebrates were collected in 59 sites. Organic and inorganic contaminants as well as sediments characteristics (grain size, organic matter, nutrient, etc) were measured in sediment. Seventeen biological or ecological traits of taxa were coded, taking into account regional climate and ecosystem specificities. The goals of this study were to: (1) link macroinvertebrate trait combinations to environmental conditions and (2) link trait combinations to quality guidelines developed for the assessment of sediment quality in Quebec.

International audience; L'indice biologique global normalisé (IBGN, 1992, 2004) est depuis des décennies l'indice invertébré utilisé dans les réseaux de surveillance français. Or, dans le contexte de la Directive Cadre Européenne sur l'Eau (2000), il a fallu repenser et faire évoluer l'indice et son mode de prélèvement de la faune pour les rendre compatible avec les exigences européennes. Nous présenterons ici quelles modifications ont été apportées par rapport à l'ancienne méthode, et pourquoi. Puis, sur la base de l'application de ce nouveau protocole, nous présenterons quelles sont les orientations pour la création du nouvel indice métropolitain.

International audience; 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. The purpose of this study is to assess sediment quality by exploring the relationships between chemical contamination and benthic community structure using classical taxonomy and functional traits approaches. 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. Taxonomy and functional traits of benthic macroinvertebrates in the St. Lawrence River will be used to assess the relative impact of chemical contamination and sediment characteristics applying multivariate analysis and variance partitioning. We will compare the potential of taxonomy and functional traits approaches for assessing sediment quality in comparison with chemical sediment quality guidelines classification. The preliminary results and the implication for the development of an ERA tiered framework will be discussed.

International audience; Benthic invertebrates are key components of food webs in particular by contributing to the transfer and transformation of allochtonous organic matter in river ecosystems. Many benthic invertebrates are known for their sensitivity to anthropogenic perturbations. One potential impact of perturbation is structural modifications in communities which can lead to functional changes. Trophic processes could be altered if community structure is deeply modified. Potential biological and ecological traits are a useful tool for studying functional characteristics of invertebrate communities. Focussing on two biological traits that describe the food and feeding habits of invertebrates, we quantified the specialization level of taxa and the intensity of trophic competition within benthic assemblages in selected mesohabitats of reference versus impacted sites. Several indices, including a new competition index, allow us to quantify the trophic specialization and trophic overlap of taxa and the within-community trophic competition intensity. The response of indices to four different perturbation types (i.e. acidification, organic pollution, habitat degradation and toxic pollution) was investigated for communities living in three mesohabitat types (cobbles, plants and litter) in 6 rivers of North-eastern France. Our results highlighted variable alteration in trophic structure depending on the perturbation and habitat types. The most drastic alteration was observed for invertebrate communities living in cobbles when subjected to organic pollution. Impacted communities were generally less specialized and exhibited lower trophic overlap than those living in reference conditions. The competition intensity was slightly affected by perturbation. Only organic pollution seemed to reduce competition intensity, but this trend was only significant for communities living in litter. This study suggests that perturbation, especially organic pollution, may alter trophic processes in rivers, through qualitative and quantitative modifications in trait profiles of taxa within benthic communities.

National audience

Pour répondre aux demandes,de la Directive Cadre Européenne 2000/60/CE sur l'eau, les états membres doivent quantifier les relations existant entre la qualité biologique et les propriétés physiques et chimiques des eaux de surface. Un tel objectif nécessite la création, le développement et la validation de nouveaux outils d'évaluation de la qualité des écosystèmes aquatiques afin de pouvoir établir un diagnostic précis de l'état écologique des eaux de surface.Nous avons analysé les réponses de plusieurs métriques fonctionnelles décrivant la structure et l'organisation des communautés benthiques aux concentrations en micropolluants observées dans les sédiments benthiques, dans le but 1) de mieux décrire l'impact toxique sur Ies communautés in situ et 2) de sélectionner une combinaison de variables bio-écologiques capable de révéler l'impact des pressions toxiques sur l'écosystème.Le travail a été réalisé à une échelle nationale, sur des données faunistiques et chimiques issues des réseaux de mesures nationaux (RNB, RNDE).La sensibilité des variables biologiques et écologiques utilisées permet de définir les changements observés dans les communautés faunistiques en fonction de la nature des micropolluants présents dans les sédiments. Même si ces relations sont assez liées à la présence d'une contamination organique, nous sommes néanmoins en mesure de relier ces pressions toxiques à certaines réponses des communautés et donc d'envisager la prise en compte de nouvelles variables dans les méthodes d'évaluation de la qualité des cours d'eau.

The European Water Framework Directive (EU WFD) has established a framework for Community action in the field water policy application which requires river assessment systems based on macrobenthic community, to express quality of structure and functioning of freshwater ecosystems..

Test species for bioassays are commonly selected on the basis of their breeding and handling facilities. These species thus provide hardly toxicological and ecological relevance to laboratory data. Biological and ecological traits of species are involved (1) in the structure and functioning of communities, (2) in species sensitivity to toxicant, and (3) in toxicity mechanisms. We thus believe that the analysis of bio/ecological trait patterns of taxa may be a relevant basis for test battery building. Using fuzzy coded information on 11 biological traits and 9 ecological traits for 700 West European macroinvertebrate taxa, we (1) selected 109 potential representatives of benthic communities inhabiting potamic environments in lowland rivers (2) assembled selected taxa in successively larger faunal groups with 'similar' suites of traits, using co-inertia analyses and a classification procedure (3) selected a species, which were the best representatives of each functional group and included them in an "ecologically relevant" test battery. The selected taxa were Branchiura sowerbyi, Lumbriculus variegatus (Oligochaeta), Valvata piscinalis (Gasteropoda), Chironomus riparius (Diptera), and Sericostoma personatum (Trichoptera). This test battery accounts for the functional diversity of lowland river benthic communities, and also for various routes of exposure and toxicant modes of action at individual and population levels. Our original species selection method makes it possible to intrinsically integrate ecological knowledge into a toxicologically designed tool and can easily be applied to any aquatic ecosystem. It should therefore provide relevant insights into improvement of risk assessment methods.

Using invertebrate life trait patterns as a biomonitoring tool for the assessment of human impact in rivers is a risingresearch field. Yet in tropical regions, the lack of detailed biological or ecological information results in great difficulties todocument such traits. Herein, we propose an approach to infer ecological traits from habitat characteristics, using ecologicalprofiles. The method was tested on river invertebrates from the Bolivian Amazon Basin, as a preliminary step prior to adaptingthis tool to the context of tropical rivers., L'étude des traits de vie des organismes constitue une approche pertinente des perturbations auxquelles sont soumises les communautés aquatiques. Or, dans les régions tropicales en général, le manque de connaissances préalables surl'écologie et la biologie des espèces constitue le plus souvent un obstacle à l'étude de ces traits. Dans cet article, nous posons les bases d`une approche permettant de déduire certains traits écologiques à partir des caractéristiques du milieu, en utilisantdes profils écologiques. Cette méthode a été testée sur les invertébrés de rivières du bassin amazonien bolivien et constitue unpremier pas vers l`adaptation de cette approche au contexte des zones tropicales.

Considering the huge variability of sensitivity (up to 106) to a toxicant among species, the choice of the tested organism can dramatically affect toxicity evaluation. The variability of sensitivity among taxa has thus to be accounted for in risk assessment methods. To fulfil this need, between-taxa differences of sensitivity to toxicants have to be better understood. We hypothesize that some biological and ecological traits can explain a large part of the between-taxa variability of sensitivity to a compound. On this hypothesis, 11 biological and 9 ecological traits that we believe to be directly involved either with the exposure level or with toxicity mechanisms at the individual scale have been selected. Using multivariate analyses and classification methods, we clustered 109 benthic invertebrate species (previously selected for their habitat characteristics from faunal lists) in 6 functional groups according to their similarities in terms of combinations of the selected biological and ecological traits. The clustering of species into functional groups allows us (1) to consider the organisms within a group as relevant combinations of biological and ecological traits, permitting us to link sensitivity with these traits; (2) to set up a rational basis for species selection on a toxicity testing perspective. The resulting taxa selection includes Chironomus riparius, Branchiura sowerbyi, Lumbriculus variegatus, Valvata piscinalis and Sericostoma personatum. Testing protocols will be developed for the non standard testing species., Nous proposons une sélection d'une batterie de tests de toxicité sur invertébrés qui se fonde sur un regroupement selon 9 critères écologiques et 11 critères biologiques pour rendre compte en partie des différences de sensibilité entre espèces. Nous sommes parvenus à la sélection de 6 groupes avec comme représentants : Chironomus riparius, Branchiura sowerbyi, Lumbriculus variegatus, Valvata piscinalis et Sericostoma personatum.

Considering the huge variability of sensitivity (up to 106) to a toxicant among species, the choice of the tested organism can dramatically affect toxicity evaluation. The variability of sensitivity among taxa has thus to be accounted for in risk assessment methods. To fulfil this need, between-taxa differences of sensitivity to toxicants have to be better understood. We hypothesize that some biological and ecological traits can explain a large part of the between-taxa variability of sensitivity to a compound. On this hypothesis, 11 biological and 9 ecological traits that we believe to be directly involved either with the exposure level or with toxicity mechanisms at the individual scale have been selected. Using multivariate analyses and classification methods, we clustered 109 benthic invertebrate species (previously selected for their habitat characteristics from faunal lists) in 6 functional groups according to their similarities in terms of combinations of the selected biological and ecological traits. The clustering of species into functional groups allows us (1) to consider the organisms within a group as relevant combinations of biological and ecological traits, permitting us to link sensitivity with these traits; (2) to set up a rational basis for species selection on a toxicity testing perspective. The resulting taxa selection includes Chironomus riparius, Branchiura sowerbyi, Lumbriculus variegatus, Valvata piscinalis and Sericostoma personatum. Testing protocols will be developed for the non standard testing species., Nous proposons une sélection d'une batterie de tests de toxicité sur invertébrés qui se fonde sur un regroupement selon 9 critères écologiques et 11 critères biologiques pour rendre compte en partie des différences de sensibilité entre espèces. Nous sommes parvenus à la sélection de 6 groupes avec comme représentants : Chironomus riparius, Branchiura sowerbyi, Lumbriculus variegatus, Valvata piscinalis et Sericostoma personatum.

The use of " life traits " addresses the description of various aspects of living world, by separating them into catégories. We intend to present the selected approach (coding traits from ecological or environmental data matiix) for several examples relevant to the neotropical invertebrates. Six aspects of invertebrates microhabitat related to hydraulic characteristics (speed, depth), substrats (surface, under-layer) and feeding sources (organic deposits, periphyton) were coded as "ecological traits".. Relevant data were from the Amazonian Bolivian basin (32 main families, 125 Surber sampling). Costructures analyses between the selected life traits and data from similar ecoregions emphasize the advantages and the limitations of this approach, especially to assess the impact of disturbances. From the comparison with the approach developped in France (Loire case study), comparative approaches can be proposed : 1) the improvement of data coding techniques and 2) the creation of a collaboration network rallying specialists which could help in deterrnining life traits when published litteratlire is unsufficient. The ultimate goal of this work is to provide information about the comparative influence of environmental disturbances on geographically separate communities., L'utilisation des " traits de vie " est une approche visant à décrire divers aspects des êtres vivants en les classant en modalités. Nous exposons la démarche adoptée pour le codage de traits à partir de tableaux de données écologiques ou environnementaux, ainsi que plusieurs exemples d'application. Six aspects du microhabitat des invertébrés relatifs aux conditions hydrauliques (vitesse, profondeur), au substrat (surface, sous-couche) et aux sources de nourriture (dépôt organique, periphyton) ont été codés à partir de données provenant du bassin amazonien bolivien (32 familles abondantes, 125 relevés Surber). L'étude des co-structures entre ces traits de vie et des jeux de données provenant d'écorégions similaires montre l'intérêt et les limites de cette approche, en particulier pour étudier l'impact de certaines perturbations. La comparaison avec l'approche développée en France (Loire) conduit à proposer 1) l'amélioration des techniques de codage et 2) la création d'un réseau de pouvant aider à définir les traits de vie lorsque la littérature publiée est insuffisante. A terme, le but de ces travaux est de préciser l'effet comparatif des perturbations au sein de communautés géographiquement distinctes.

The use of " life traits " addresses the description of various aspects of living world, by separating them into catégories. We intend to present the selected approach (coding traits from ecological or environmental data matiix) for several examples relevant to the neotropical invertebrates. Six aspects of invertebrates microhabitat related to hydraulic characteristics (speed, depth), substrats (surface, under-layer) and feeding sources (organic deposits, periphyton) were coded as "ecological traits".. Relevant data were from the Amazonian Bolivian basin (32 main families, 125 Surber sampling). Costructures analyses between the selected life traits and data from similar ecoregions emphasize the advantages and the limitations of this approach, especially to assess the impact of disturbances. From the comparison with the approach developped in France (Loire case study), comparative approaches can be proposed : 1) the improvement of data coding techniques and 2) the creation of a collaboration network rallying specialists which could help in deterrnining life traits when published litteratlire is unsufficient. The ultimate goal of this work is to provide information about the comparative influence of environmental disturbances on geographically separate communities., L'utilisation des " traits de vie " est une approche visant à décrire divers aspects des êtres vivants en les classant en modalités. Nous exposons la démarche adoptée pour le codage de traits à partir de tableaux de données écologiques ou environnementaux, ainsi que plusieurs exemples d'application. Six aspects du microhabitat des invertébrés relatifs aux conditions hydrauliques (vitesse, profondeur), au substrat (surface, sous-couche) et aux sources de nourriture (dépôt organique, periphyton) ont été codés à partir de données provenant du bassin amazonien bolivien (32 familles abondantes, 125 relevés Surber). L'étude des co-structures entre ces traits de vie et des jeux de données provenant d'écorégions similaires montre l'intérêt et les limites de cette approche, en particulier pour étudier l'impact de certaines perturbations. La comparaison avec l'approche développée en France (Loire) conduit à proposer 1) l'amélioration des techniques de codage et 2) la création d'un réseau de pouvant aider à définir les traits de vie lorsque la littérature publiée est insuffisante. A terme, le but de ces travaux est de préciser l'effet comparatif des perturbations au sein de communautés géographiquement distinctes.

International audience; Faunal and chemical data from mountain streams in France were analysed to examine the accuracy of a multimetric approach based on biological and ecological traits of benthic macroinvertebrate communities to assess toxic sediment pollution in streams. A toxic quality class (from high' to bad') was pre-assigned to each site using the French water quality assessment system based on toxic substances (metals, PAH, PCB) in sediment. Each trait was described in multiple categories. The affinity of macroinvertebrate taxa for the different categories of a trait was described using a fuzzy coding procedure. The relative abundance of trait categories was calculated for communities at each site. A non-parametric multiple comparison statistical procedure was used to compare relative abundances of trait categories between groups of sites assigned to different quality classes to identify the combinations of trait categories that best separated sites between adjacent toxic quality classes. Based on such sets of trait categories, we propose a statistical procedure to allocate sites to toxic quality classes from the attributes of its benthic macroinvertebrate community. This study shows that biological criteria based on macroinvertebrate traits could provide new methods for biological assessment. This is the first step towards an in situ functional tool of stream sediment contamination assessment at community level. However, we need to increase the number of sites to improve the tool's precision, extend the procedure to additional stream types and validate the design at a larger spatial scale.

International audience; The purpose of our approach was to take account of the nested scales of stream functioning on the links between pressures and ecological status by building and analysing a hierarchical model. The development of this model aimed at answering the following questions: Does the indirect links between pressures and ecological status modify the impact hierarchy of pressures? Do the different nested scales play a different role in the pressures-ecological status relationship? To achieve that goal, we used the PLS path modelling method for developing a structural model linking the latent variables of (i) land use, and hydromorphological alterations at watershed scale, (ii) hydromorphological alterations at reach scale, (ii) nutrients-organic matter contamination levels, and (iv) substrate samples to explain macroinvertebrate based index I2M2 score variation. As a first important result, we have highlighted the importance of land use effect exerted on both hydromorphology and physico-chemistry and their translation as an indirect effect on biological condition of streams. We have also demonstrated that hydromorphological alterations had an effect on substrates structure and nutrients and organic matter concentrations. This result implies that hydromorphology has a major indirect effect on macroinvertebrates.

International audience; The St-Lawrence River is an essential waterway for North America and is exposed to many anthropogenic stresses such as industrial and municipal wastewater or by the agricultural activities. 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. The purposes of this part of the study are to develop traits approach for the St. Lawrence River and to assess sediment quality by exploring the relationships between chemical contamination and benthic community structure using traits approach. 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. To build the matrix of traits, we made a bibliographical research at the level of the genus characteristic. The traits were coded by taking into account regional peculiarities of climate and the same ecozone. The relative influence of the chemical contamination and the environmental characteristics on the structure of the bioecological traits was estimated by multivariate analyses. The results of stations clustering according to the traits, significant indicators traits according to the clusters and the relations with the explanatory variables will presented.

Autres; La présente note concerne uniquement les macro-invertébrés dans les cours d'eau. Elle a pour objet de proposer un nouveau protocole de prélèvement et de traitement des échantillons pour le réseau de contrôle de surveillance, dans le cadre de la mise en ½uvre de la Directive cadre européenne sur l'eau (DCE). Le protocole proposé s'applique aux cours d'eau dont la totalité ou la quasi totalité des habitats présents dans le lit mouillé peuvent être prospectés en période de basses eaux, à pied ou au moyen d'embarcation légères, avec des appareils à main de type filet Surber.