Summary 1.The need for sensitive biological measures of aquatic ecosystem integrity applicable at large spatial scales has been highlighted by the implementation of the European Water Framework Directive. Using fish communities as indicators of habitat quality in rivers, we developed a multi-metric index to test our capacity to (i) correctly model a variety of metrics based on assemblage structure and functions, and (ii) discriminate between the effects of natural vs. human-induced environmental variability at a continental scale. 2. Information was collected for 5252 sites distributed among 1843 European rivers. Data included variables on fish assemblage structure, local environmental variables, sampling strategy and a river basin classification based on native fish fauna similarities accounting for regional effects on local assemblage structure. Fifty-eight metrics reflecting different aspects of fish assemblage structure and function were selected from the available literature and tested for their potential to indicate habitat degradation. 3. To quantify possible deviation from a 'reference condition' for any given site, we first established and validated statistical models describing metric responses to natural environmental variability in the absence of any significant human disturbance. We considered that the residual distributions of these models described the response range of each metric, whatever the natural environmental variability. After testing the sensitivity of these residuals to a gradient of human disturbance, we finally selected 10 metrics that were combined to obtain a European fish assemblage index. We demonstrated that (i) when considering only minimally disturbed sites the index remains invariant, regardless of environmental variability, and (ii) the index shows a significant negative linear response to a gradient of human disturbance. 4. Synthesis and applications . In this reference condition modelling approach, by including a more complete description of environmental variability at both local and regional scales it was possible to develop a novel fish biotic index transferable between catchments at the European scale. The use of functional metrics based on biological attributes of species instead of metrics based on species themselves reduced the index sensitivity to the variability of fish fauna across different biogeographical areas.

Here, we employ an additive partitioning framework to disentangle the contribution of spatial turnover and nestedness to beta diversity patterns in the global freshwater fish fauna. We find that spatial turnover and nestedness differ geographically in their contribution to freshwater fish beta diversity, a pattern that results from contrasting influences of Quaternary climate changes. Differences in fish faunas characterized by nestedness are greater in drainage basins that experienced larger amplitudes of Quaternary climate oscillations. Conversely, higher levels of spatial turnover are found in historically unglaciated drainage basins with high topographic relief, these having experienced greater Quaternary climate stability. Such an historical climate signature is not clearly detected when considering the overall level of beta diversity. Quantifying the relative roles of historical and ecological factors in explaining present-day patterns of beta diversity hence requires considering the different processes generating these patterns and not solely the overall level of beta diversity.

Explanations of spatial and temporal variation in species richness is a central theme in community ecology Until recently, most research has focused on small‐scale phenomena, often emphasizing on local environmental factors and, thus, poorly reflecting large‐scale processes that organize species richness In this paper, we analyze variations in species richness of indigeneous freshwater fish on a worldwide scale We show that factors related to species‐area and species‐energy theories statistically explain most of the variation in freshwater fish species richness across continents Historical events supposed to influence present distributions offish are of little assistence in explaining variations in fish species richness at the global scale Our model, which uses easily measured factors, should also be of practical value to aquatic conservation biology and natural resource management

SUMMARY 1. In Europe, water policy is currently undergoing considerable change as emphasised by the recent European Water Framework Directive (WFD), which requires the restoration and maintenance of ‘healthy’ aquatic ecosystems by the assessment of their hydromorphological, chemical and biological characteristics. If the requirements of the WFD are to be met, effective biological tools are needed to measure the ‘health’ of rivers at scales large enough to be useful for management. These tools need to be ecologically based, efficient, rapid and applicable in different ecological regions. Among potential indicators, fish assemblages are of particular interest because of their ability to integrate environmental variability at different spatial scales. To meet the goals of the WFD, the French Water Agencies and the Ministry of the Environment initiated a research programme to develop a fish‐based index that would be applicable nationwide. 2. A variety of metrics based on occurrence and abundance data and reflecting different aspects of the fish assemblage structure and function were selected from available literature and for their potential to indicate degradation. 3. Logistic and multiple linear regression procedures were applied, using an initial data set of 650 reference sites fairly evenly distributed across French rivers and defined by some easily measured regional and local characteristics, to elaborate the simplest possible response model that adequately explained the observed patterns of each metric for a given site. 4. Models obtained for each metric were validated using two independent data sets of 88 reference sites and 88 disturbed sites. These procedures allowed us to select the most effective metrics in discriminating between reference and disturbed sites.

1. Management of running waters and assessment of water quality trends require the use of biological methods. Among potential indicators, fish assemblages are of particular interest because of their ability to integrate environmental variability at different spatial scales. 
2. The French Water Agencies and the Ministry of the Environment initiated a research programme to develop a fish‐based index that would be applicable nation‐wide. Such an index should encompass the relative importance of geographic, ecoregional and local factors influencing the distribution of riverine fishes. 
3. An effective way of using the information available from fish assemblages to establish such an index is through the use of the ‘reference condition approach’ which involves testing a fish assemblage exposed to a potential stress against a reference condition that is unexposed to such a stress. 
4. Logistic regression procedures were applied, using a fish data set of 650 reference sites fairly evenly distributed across French rivers and defined by some easily measured regional and local characteristics, to elaborate the simplest possible response model that adequately explains the observed patterns of occurrence for each species of a fish assemblage at a given site of any given river. This allows us to predict a ‘theoretical’ assemblage at a site. 
5. The models were validated using a second independent data set of 88 reference sites. Using a third data set of 88 disturbed sites, the observed assemblages were then compared against the reference condition as defined by the ‘theoretical’ assemblages. The amount of deviation between the expected and observed assemblages within these sites is used as a measure of degradation. 
6. This approach could be used as a framework for adapting and calibrating a multimetric index, thereby serving as a practical technical reference for conducting cost‐effective biological assessments of lotic systems.

Aim To analyse the patterns in species richness and endemism of the native European riverine fish fauna, in the light of the Messinian salinity crisis and the Last Glacial Maximum (LGM). Location European continent.Methods After gathering native fish faunistic lists of 406 hydrographical networks, we defined large biogeographical regions with homogenous fish fauna, based on a hierarchical cluster analysis. Then we analysed and compared the patterns in species richness and endemism among these regions, as well as species-area relationships.

Understanding the action of filters on the biological trait composition of communities is constrained by the multitude of filter types (e.g. abiotic vs biotic, actual vs historical) that may cause changes of a multitude of traits (e.g. small vs large body size, short vs long life cycle) at a multitude of spatial scales (e.g. continent vs landscape vs local site). Using published data on the as natural as possible abundances and 11 biological traits (described through 63 categories) of 254 European stream invertebrate genera, we assessed how already available knowledge can serve to identify the importance of the action of different types of trait filters at two spatial scales. Therefore, we analysed observed and simulated abundance‐weighted trait compositions at the local scale of 384 running water sites (RWS) and at the landscape scale of 14 large biogeographical regions (LER). Actual abiotic filters acted significantly and independently of the taxonomic richness on the invertebrate traits at the RWS‐ and LER‐scale, whereas biotic filters had no significant effect. Evidence for the action of historical trait filters across Europe was only weak at both scales. Size, reproductive cycle, respiration and locomotion technique, feeding habits and vulnerability to disturbance responded to altitude and stream width of the RWS according to existing views about the effects of riparian, physiological, interstitial or disturbance controls of these traits. These controls acted independently on trait categories that did not co‐occur within the genera, because correlations of size categories with other trait categories were higher in the abundance‐weighted trait array (across communities) than in the original trait array (across genera). Overall, many of the 63 trait categories were scarcely affected by the trait filters considered in this study. Therefore, we briefly discuss potential effects of continental filters and of stream system‐specific, local physical filters, as the latter should produce similar trait patterns on a global scale. Our study suggests that analyses of the currently available knowledge can simplify the complicated hypothetical framework on trait filter actions, which sharpens the focus on future research needs.

A growing interest is devoted to global-scale approaches in ecology and evolution that examine patterns and determinants of species diversity and the threats resulting from global change. These analyses obviously require global datasets of species distribution. Freshwater systems house a disproportionately high fraction of the global fish diversity considering the small proportion of the earth’s surface that they occupy, and are one of the most threatened habitats on Earth. Here we provide complete species lists for 3119 drainage basins covering more than 80% of the Earth surface using 14953 fish species inhabiting permanently or occasionally freshwater systems. The database results from an extensive survey of native and non-native freshwater fish species distribution based on 1436 published papers, books, grey literature and web-based sources. Alone or in combination with further datasets on species biological and ecological characteristics and their evolutionary history, this database represents a highly valuable source of information for further studies on freshwater macroecology, macroevolution, biogeography and conservation.