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1. The main objectives of our study were (i) to establish the relative impact of pressures that degrade ecological status, especially those caused by agriculture and urbanisation, (ii) to identify regional patterns in these pressure-impact relationships and (iii) to evaluate the relative weight of the pressures acting at the basin and riparian corridor scales, and the possible buffering effect of riparian areas. 2. We developed large-scale models linking invertebrate indices of ecological quality to river basin and riparian land cover in France, Slovakia, Estonia and U.K. Invertebrate indices, transformed to ecological quality ratios (EQR), were taken from national monitoring networks. We based the models on partial least squares (PLS) regressions at national and a hydro-ecoregion (HER) scales. The HERs provided a framework for grouping data in terms of natural river features and human activities. 3. The different national methods provided consistent results that indicated the hierarchy of pressures impacting river invertebrates at the European scale. Artificial land cover (e.g. urban and industrial sites) in the river basin represented the pressure with the most negative impact on invertebrate indices, in all countries and regions. 4. The impact of agricultural land cover was more variable. Arable land had a smaller impact than urban areas and was insignificant in some models. The proportion of arable land in the river basin appeared to be a weak predictor of agricultural impacts by itself; the type of cultivation and intensity as well as the proximity to the river must be taken into account. 5. At the riparian corridor scale, the negative impact of artificial areas or arable land and the positive effects of forests and pastures were demonstrated in many regions. The protective effect of riparian forests against mixed agricultural and urban pressures was demonstrated in three regions in France. Riparian corridors appear to be manageable areas, and these results strongly support the idea of including their restoration in priority actions for achieving good ecological status. [ABSTRACT FROM AUTHOR]

1. We examined the accuracy of a multimetric approach based on 22 biological and ecological traits of benthic macroinvertebrate communities to assess toxic sediment pollution in streams. 2. Faunal and chemical data from sites located on 150 medium-sized mountain streams in France were analysed. We used 18 additional sites, not included in the multimetric tool development as a test data set. A toxic quality class (from ‘high’ to ‘poor/bad’) was pre-assigned to each site using the French water quality assessment system (SEQ-Eau) based on toxic substances (metals, PAH and PCB) in sediment. 3. 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. 4. A nonparametric multiple comparison statistical procedure was used to compare relative abundances of trait categories between groups of sites assigned to different quality classes (e.g. high versus good; good versus moderate, etc.), 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. 5. Predictions from the trait-based functional tool achieved approximately 73% of correct site post-assignments to toxic quality classes pre-assigned using chemical criteria. All of the sites pre-assigned to the ‘high’ quality class, were post-classified into the same quality class using benthic community attributes. From 0–90% of sites from other quality classes were classified identically using both chemistry- and trait-based criteria, the observed biological impact being often lower than expected. We suggest that the rapid decline of sensitive species could lead to both low taxonomic richness and low diversity of adaptations, giving communities a less diverse range of potential functional responses to increasing toxic pressure. 6. Biological criteria based on macroinvertebrate traits could provide new methods for biological assessment. This study 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 included in the development data set to improve the tool’s precision, extend the procedure to additional stream types and validate the design at a larger spatial scale. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Integrated management of aquatic ecosystems is a common concern for water resources managers as well as for researchers. The 1992 French Water Act aims to preserve the biotic and ecological integrity of aquatic ecosystems as part of water management schemes, creating needs for new methodologies for studying these systems. This paper describesthe partitioning of the Loire basin (105 000 km2, France)into hydro-ecoregions tested at the mesohabitat scale. The followingnull hypotheses were examined in the four largest hydro-ecoregions of the basin: (1) differences in mesohabitat types distribution do notexist between regions; (2) the longitudinal structure of mesohabitattypes distribution is not different between regions; and (3) the factors governing distribution and longitudinal evolution of mesohabitats distribution are not different between regions. It was found that the four regions behaved in different ways in terms of distribution and longitudinal evolution of mesohabitats. Valley slope and stream order, the two tested control variables, do not play the same role in each region. If the region contains mainly alluvial rivers, slope and/or order do explain or predict mesohabitat distributions. If the region contains cohesive rivers, these factors do not, or poorly explain, mesohabitat distributions. Since predictive models cannot be developed in most regions for mesohabitat distributions, it is necessary to build descriptive models at the regional scale. In addition to one regional predictive model, this paper provides such results for three regions of the Loire basin. [ABSTRACT FROM AUTHOR]

Abstract: One objective of the European Union (EU)''s Water Framework Directive (WFD: Directive 2000/60/EC) is for all European surface waters to achieve ‘good status’ by 2015. In support of this objective, the EU has facilitated an intercalibration exercise to ensure harmonized definitions of the status of water bodies, reflecting the deviation of their properties (mainly biotic assemblages) from a minimally disturbed state, termed the “reference condition”. One of the major challenges of the WFD has been to find common approaches for defining reference conditions and to define the level of anthropogenic intervention allowed in reference sites. In this paper we describe how river reference sites were selected in the Central-Baltic region of Europe. A list of pressure criteria was provided and 14 Member States (MSs) categorized each criterion according to the method (i.e. measured, field inspection, etc.) used for reference site screening. Additionally, reference land-use and water-chemistry thresholds were agreed among countries in order to base reference site selection on objective criteria. For land-use criteria, a reference threshold and a rejection threshold were established. Sites with all criteria below the reference threshold were considered to be reference sites; sites having most criteria below the reference threshold and only some parameters between the reference and rejection threshold were “possible reference sites”. These sites were retained only after carefully checking the cumulative effects of the pressures using local expertise, and a posteriori water-chemistry evaluation was necessary. In general, the most widespread method for defining a reference site was the measurement of pressures, followed by field inspections and expert judgment. However, some major pressures (e.g. hydromorphological alteration) were evaluated in a number of different ways (e.g. measured, field inspection, expert judgment). Our meta-analyses reveal a need to reinforce standardization in the application of pressure criteria by Member States. The pressure criteria identified in this exercise should be refined and tested with biological data to help in the further validation of minimally disturbed sites (i.e. the WFD “reference condition”) and to provide a firm foundation for ecological status assessment. This in turn would ensure that there is pan-European comparability when evaluating the achievement of environmental objectives. [Copyright &y& Elsevier]