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Funding: W.B.X., S.A.B., J.M.C., R.v.K., and D.M. were supported by the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, funded by the German Research Foundation (DFG FZT-118, 20254881); B.J.M. was supported by NSF EPSCOR Track II 201947 and USDA Hatch grant (MAFES #1011538); N.J.G was supported by NSF EPSCOR Track II 201947; I.S.M. was supported by the European Union’s Horizon 2020 research and innovation program under Marie Sklodowska -Curie grant (no. 894644); H.S. was supported by Japan Society for the Promotion of Science (JP19K21569 and JP21H03402); A.E.M. and M.D. were supported by Leverhulme Trust (RPG-2019-402). A.F.E acknowledges the Fisheries Society of the British Isles Studentship. BioTIME used here was supported by ERC AdG 250189 and PoC 727440 (to A.E.M.), and Leverhulme Trust Research Centre–the Leverhulme Centre for Anthropocene Biodiversity (to M.D.). While human activities are known to elicit rapid turnover in species composition through time, the properties of the species that increase or decrease their spatial occupancy underlying this turnover are less clear. Here, we used an extensive dataset of 238 metacommunity time series of multiple taxa spread across the globe to evaluate whether species that are more widespread (large-ranged species) differed in how they changed their site occupancy over the 10–90 years the metacommunities were monitored relative to species that are more narrowly distributed (small-ranged species). We found that on average, large-ranged species tended to increase in occupancy through time, whereas small-ranged species tended to decrease. These relationships were stronger in marine than in terrestrial and freshwater realms. However, in terrestrial regions, the directional changes in occupancy were less extreme in protected areas. Our findings provide evidence for systematic decreases in occupancy of small-ranged species, and that habitat protection could mitigate these losses in the face of environmental change. Publisher PDF

Biotic responses to global change include directional shifts in organismal traits. Body size, an integrative trait that determines demographic rates and ecosystem functions, is often thought to be shrinking in the Anthropocene. Here, we assess the prevalence of body size change in six taxon groups across 5,032 assemblage time-series spanning 1960-2020. Using the Price equation to partition this change into within-species body size versus compositional changes, we detect prevailing decreases in body size through time. Change in assemblage composition contributes more to body size changes than within-species trends, but both components show substantial variation in magnitude and direction. The biomass of assemblages remains remarkably stable as decreases in body size trade-off with increases in abundance.One-Sentence SummaryVariable within-species and compositional trends combine into shrinking body size, abundance increases and stable biomass.

Earth’s biodiversity continues to change rapidly through the Anthropocene1, including widespread reordering of species in space2,3 and time4,5. A common expectation of this reordering is that the species composition of sites is becoming increasingly similar across space, known as biotic homogenization, due to anthropogenic pressures and invasive species6,7. While many have argued that homogenisationis a common phenomenon (e.g., 6–10), it is equally plausible that communities can become more different through time, known as differentiation, including through human impacts11,12. Here, we used a novel adaptation of Whittaker’s (1960)13 spatial-scale explicit diversity partition to assess the prevalence of biotic homogenisation and differentiation, and associated changes in species richness at smaller and larger spatial scales. We applied this approach to a compilation of species assemblages from 205 metacommunities that were surveyed for 10-64 years, and 54 ‘checklists’ that spanned 50-500+ years. Scale-dependent changes of species richness were highly heterogeneous, with approximately equal evidence for homogenisation(i.e., lower β-diversity) and differentiation (i.e., higher β-diversity) through time across all regions, taxa and data types. Homogenisation was most often due to increased numbers of widespread species, which tended to increase both local and regional richness through time. These results emphasise that an explicit consideration of spatial scale is needed to fully understand biodiversity change in the Anthropocene.

Agriculture is a leading cause of biodiversity loss and significantly impacts freshwater biodiversity through many stressors acting locally and on the landscape scale. The individual effects of these numerous stressors are often difficult to disentangle and quantify, as they might have nonlinear impacts on biodiversity. Within agroecosystems, ponds are biodiversity hotspots providing habitat for many freshwater species and resting or feeding places for terrestrial organisms. Ponds are strongly influenced by their terrestrial surroundings, and understanding the determinants of biodiversity in agricultural landscapes remains difficult but crucial for improving conservation policies and actions. We aimed to identify the main effects of environmental and spatial variables on α-, β-, and γ-diversities of macroinvertebrate communities inhabiting ponds (n = 42) in an agricultural landscape in the Northeast Germany, and to quantify the respective roles of taxonomic turnover and nestedness in the pondscape. We disentangled the nonlinear effects of a wide range of environmental and spatial variables on macroinvertebrate α- and β-biodiversity. Our results show that α-diversity is impaired by eutrophication (phosphate and nitrogen) and that overshaded ponds support impoverished macroinvertebrate biota. The share of arable land in the ponds' surroundings decreases β-diversity (i.e., dissimilarity in community), while β-diversity is higher in shallower ponds. Moreover, we found that β-diversity is mainly driven by taxonomic turnover and that ponds embedded in arable fields support local and regional diversity. Our findings highlight the importance of such ponds for supporting biodiversity, identify the main stressors related to human activities (eutrophication), and emphasize the need for a large number of ponds in the landscape to conserve biodiversity. Small freshwater systems in agricultural landscapes challenge us to compromise between human demands and nature conservation worldwide. Identifying and quantifying the effects of environmental variables on biodiversity inhabiting those ecosystems can help address threats impacting freshwater life with more effective management of pondscapes.

SAB, TE, AS, and JMC were supported by the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, funded by the German Research Foundation (FZT 118). Biodiversity metrics often integrate data on the presence and abundance of multiple species. Yet our understanding of covariation between changes to the numbers of individuals, the evenness of species relative abundances, and the total number of species remains limited. Using individual-based rarefaction curves, we introduce a conceptual framework to understand how expected positive relationships among changes in abundance, evenness and richness arise, and how they can break down. We then examined interdependencies between changes in abundance, evenness and richness in more than 1100 assemblages sampled either through time or across space. As predicted, richness changes were greatest when abundance and evenness changed in the same direction, and countervailing changes in abundance and evenness acted to constrain the magnitude of changes in species richness. Site-to-site differences in abundance, evenness, and richness were often decoupled, and pairwise relationships between these components across assemblages were weak. In contrast, changes in species richness and relative abundance were strongly correlated for assemblages varying through time. Temporal changes in local biodiversity showed greater inertia and stronger relationships between the component changes when compared to site-to-site variation. Overall, local variation in assemblage diversity was rarely due to repeated passive samples from an approximately static species abundance distribution. Instead, changing species relative abundances often dominated local variation in diversity. Moreover, how changing relative abundances combined with changes to total abundance frequently determined the magnitude of richness changes. Embracing the interdependencies between changing abundance, evenness and richness can provide new information for better understanding biodiversity change in the Anthropocene. Publisher PDF

1. The process of standardizing taxon names, taxonomic name harmonization, is necessary to properly merge data indexed by taxon names. The large variety of taxonomic databases and related tools are often not well described. It is often unclear which databases are actively maintained or what is the original source of taxonomic information. In addition, software to access these databases is developed following non-compatible standards, which creates additional challenges for users. As a result, taxonomic harmonization has become a major obstacle in ecological studies that seek to combine multiple datasets. 2. Here, we review and categorize a set of major taxonomic databases publicly available as well as a large collection of R packages to access them and to harmonize lists of taxon names. We categorized available taxonomic databases according to their taxonomic breadth (e.g. taxon-specific vs multi-taxa) and spatial scope (e.g. regional vs global), highlighting strengths and caveats of each type of database. We divided R packages according to their function, (e.g. syntax standardization tools, access to online databases, etc.) and highlighted overlaps among them. We present our findings (e.g. network of linkages, data and tool characteristics) in a ready-to-use Shiny web application (available at: https://mgrenie.shinyapps.io/taxharmonizexplorer/). 3. We also provide general guidelines and best practice principles for taxonomic name harmonization. As an illustrative example, we harmonized taxon names of one of the largest databases of community time series currently available. We showed how different workflows can be used for different goals, highlighting their strengths and weaknesses and providing practical solutions to avoid common pitfalls. 4. To our knowledge, our opinionated review represents the most exhaustive evaluation of links among and of taxonomic databases and related R tools. Finally, based on our new insights in the field, we make recommendations for users, database managers, and package developers alike.

The quantity and quality of ecological data have rapidly increased in the last decades, bringing ecology into the realm of big data. Frequently, multiple databases with different origins and data characteristics are combined to address new research questions. Taxonomic name harmonization, i.e., the process of standardizing taxon names according to common sources such as taxonomic databases (TD), is necessary to properly combine multiple databases using species names. In order to be able to develop proper data matching workflows, TDs and tools using them need to be clearly and comprehensively described. But this is rarely the case. Common problems users have to deal with are: poorly described taxonomic concepts behind biological databases, lack of information when TDs are actively updated, and details regarding where the primary source of taxonomic information comes from (e.g., secondary TDs taking information from primary TDs). In addition, software to access these TDs is not always advertised, partly redundant, or developed with incompatible standards, creating additional challenges for users. As a result, taxonomic name harmonization has become a major difficulty in ecological studies. Researchers face a jungle of primary and secondary TDs with a diversity of tools to access them and no clear workflow on how to practically proceed. As a consequence, it is hard for users to know which TD, tool and workflow will fit the task at hand and lead to the most robust results when combining different biological datasets. Here, we present an overview of major TDs as well as an extensive review of R packages to access TDs, and to harmonize taxa names. We developed an R Shiny web application summarizing meta-data and linkages among TDs and R packages (Figs 1, 2), which users can explore to learn about general features of TDs and tools and how they are linked among one another. This is particularly helpful to assist users when deciding on the TDs and tools that best fit the tasks and data at hand and to develop more informed workflows for taxonomic name harmonization. Finally, from our review and using the Shiny app, we were able to provide general best practice principles to harmonize taxonomic names and avoid common pitfalls. To our knowledge, this study represents the most exhaustive review of TDs and R tools for taxonomic name harmonization. Our intuitive Shiny app can help make practical decisions when harmonizing taxonomic names across multiple datasets. Finally, our proposed workflows, based on conservative guideline principles (e.g., making sure incompatible taxonomic hypotheses are not combined together), provide a hands-on approach for taxonomic harmonization, which focuses on the quality of the end results while maximizing the number of species correctly matched.

Biodiversity metrics often integrate data on the presence and abundance of multiple species. Yet our understanding of how changes to the numbers of individuals, the evenness of species’ relative abundances, and the total number of species covary remains limited, both theoretically and empirically. Using individual-based rarefaction curves, we first show how expected positive relationships among changes in abundance, evenness and richness arise, and how they can break down. We then examined the interdependency between changes in abundance, evenness and richness more than 1100 assemblages sampled either through time or across space. As expected, richness changes were greatest when abundance and evenness changed in the same direction, whereas countervailing changes in abundance and evenness acted to constrain the magnitude of changes in species richness. Site-to-site variation in diversity was greater than rates of change through time. Moreover, changes in abundance, evenness, and richness were often spatially decoupled, and pairwise relationships between changes in these components were weak between sites. In contrast, changes in species richness and relative abundance were strongly correlated for assemblages sampled through time, meaning temporal changes in local biodiversity showed greater inertia and stronger relationships between the components changes when compared to site-to-site variation. Both temporal and spatial variation in local assemblage diversity were rarely attributable solely to changes in assemblage size sampling more or less of a static species abundance distribution. Instead, changing species’ relative abundances often dominate local variation in diversity. Moreover, how these altered patterns of relative abundance combine with changes to total abundance strongly determine the magnitude of richness changes. Interdependencies found here suggest looking beyond changes in abundance, evenness and richness as separate responses offering unique insights into diversity change can increase our understanding of biodiversity change.

Aim: The island species���area relationship (ISAR) quantifies how the number of species increases as the area of an island or island-like habitat gets larger and is one of the most general patterns in ecology. However, studies that measure the ISAR often confound variation in sampling methodology and analyses, precluding appropriate syntheses of its underlying mechanisms. Most ISAR studies use only presence���absence data at the whole-island scale, whereas we planned to use a framework that applies individual-based rarefaction to synthesize whether and how the ISAR differs from the null expectation of the passive sampling hypothesis. Location: Five hundred and five islands from 34 different archipelagos across the world, including oceanic islands, lake islands and forest islands. Major taxa studied: Local assemblages of plants, invertebrates, herpetofauna, birds and mammals. Methods: We collated local-scale species abundance data from multiple archipelagos (median of 12 islands per study) and used a rarefaction-based approach to synthesize the relationship between island size and (1) sample effort-controlled rarefied species richness, or (2) an effective number of species derived from the probability of interspecific encounter (an index of community evenness). Results: When we applied rarefaction to control for sampling effort, the numbers of species and their relative abundances across all studies differed from the passive sampling hypothesis. Our measure of evenness also increased with island size, suggesting that the disproportionate effects we observed influenced both rarer and more common species. We found few associations between the slope of this effect and island type or taxon, but we did find that island archipelagos with greater elevational heterogeneity also deviated more from the null expectation than those with less heterogeneity. Main conclusions: Using a synthetic approach across island archipelagos, we reject the null expectation that passive sampling causes the ISAR and instead suggest that ecological mechanisms leading to disproportionate (non-random) effects on larger relative to smaller islands are predominant.

Background and aims Since its emergence in the mid‐20th century, invasion biology has matured into a productive research field addressing questions of fundamental and applied importance. Not only has the number of empirical studies increased through time, but also has the number of competing, overlapping and, in some cases, contradictory hypotheses about biological invasions. To make these contradictions and redundancies explicit, and to gain insight into the field’s current theoretical structure, we developed and applied a Delphi approach to create a consensus network of 39 existing invasion hypotheses. Results The resulting network was analysed with a link‐clustering algorithm that revealed five concept clusters (resource availability, biotic interaction, propagule, trait and Darwin’s clusters) representing complementary areas in the theory of invasion biology. The network also displays hypotheses that link two or more clusters, called connecting hypotheses , which are important in determining network structure. The network indicates hypotheses that are logically linked either positively (77 connections of support) or negatively (that is, they contradict each other; 6 connections). Significance The network visually synthesizes how invasion biology’s predominant hypotheses are conceptually related to each other, and thus, reveals an emergent structure – a conceptual map – that can serve as a navigation tool for scholars, practitioners and students, both inside and outside of the field of invasion biology, and guide the development of a more coherent foundation of theory. Additionally, the outlined approach can be more widely applied to create a conceptual map for the larger fields of ecology and biogeography., Global Ecology and Biogeography, 29 (6), ISSN:1466-822X, ISSN:1466-8238

Associated data is available at: https://doi.org/10.5061/dryad.595718c; International audience; Habitat destruction is the single greatest anthropogenic threat to biodiversity. Decades of research on this issue have led to the accumulation of hundreds of data sets comparing species assemblages in larger, intact, habitats to smaller, more fragmented, habitats. Despite this, little synthesis or consensus has been achieved, primarily because of non-standardized sampling methodology and analyses of notoriously scale-dependent response variables (i.e., species richness). To be able to compare and contrast the results of habitat fragmentation on species’ assemblages, it is necessary to have the underlying data on species abundances and sampling intensity, so that standardization can be achieved. To accomplish this, we systematically searched the literature for studies where abundances of species in assemblages (of any taxa) were sampled from many habitat patches that varied in size. From these, we extracted data from several studies, and contacted authors of studies where appropriate data were collected but not published, giving us 117 studies that compared species assemblages among habitat fragments that varied in area. Less than one-half (41) of studies came from tropical forests of Central and South America, but there were many studies from temperate forests and grasslands from all continents except Antarctica. Fifty-four of the studies were on invertebrates (mostly insects), but there were several studies on plants (15), birds (16), mammals (19), and reptiles and amphibians (13). We also collected qualitative information on the length of time since fragmentation. With data on total and relative abundances (and identities) of species, sampling effort, and affiliated meta-data about the study sites, these data can be used to more definitively test hypotheses about the role of habitat fragmentation in altering patterns of biodiversity. There are no copyright restrictions. Please cite this data paper and the associated Dryad data set if the data are used in publications.

Ecological effects of alien species can be dramatic, but management and prevention of negative impacts are often hindered by crypticity of the species or their ecological functions. Ecological functions can change dramatically over time, or manifest after long periods of an innocuous presence. Such cryptic processes may lead to an underestimation of long-term impacts and constrain management effectiveness. Here, we present a conceptual framework of crypticity in biological invasions. We identify the underlying mechanisms, provide evidence of their importance, and illustrate this phenomenon with case studies. This framework has potential to improve the recognition of the full risks and impacts of invasive species.

Biological indicators are frequently used to assess the effects of anthropogenic stressors on freshwater ecosystems. The structure of fish communities and their response to stressors have been commonly described by taxonomic richness, diversity and evenness. More recently, functional structure of communities has also been suggested to be a reliable indicator of disturbance. This article aimed at testing whether taxonomic and functional diversity metrics can provide comparable or complementary information on the response of fish communities to eutrophication and abundance of non-native species in reservoirs. Comparison of the responses of taxonomic and functional diversities to biogeography, habitat and stressors was made in 112 French reservoirs. Widely observed effects of biogeographic and habitat variables on taxonomic and functional diversities were identified. Taxonomic and functional richness metrics notably increased with lake area and temperature respectively. Taxonomic diversity metrics did not respond to any stressor, while all functional diversity metrics were found to be impacted by non-native species. Eutrophication was further found to decrease the impact of non-native species on two functional diversity metrics: evenness and divergence. Our study therefore reveals that functional metrics are more sensitive than taxonomic metrics to anthropogenic stressors in the studied reservoirs. Still, the multiple linear regressions tested had overall low explanatory power. Further refinements will thus be needed to use this type of metrics in an impact assessment scheme.

In naturally disturbed systems, harsh environmental conditions act as filters on the regional species pool, restricting the number of taxa able to form a local community to those with traits promoting resistance or resilience. Thus, communities in highly disturbed ecosystems may be less sensitive to a given disturbance than those in less disturbed ecosystems. We explored this idea by examining the response of aquatic invertebrate communities to flow intermittence in gravel-bed, braided rivers (BRs). Flow intermittence is considered a major driver of communities in rivers, but its influence on communities in BRs, which are recognized as naturally highly disturbed environments, is relatively unexplored. We used a multisite Before-After–Control-Impact (BACI) design to quantify the effects of drying events of different durations (moderate: 2–3 wk, severe: 1–3 mo) on invertebrate communities in 8 BRs in southeastern France. As predicted, no effects of flow intermittence were detected 1 to 4 mo after fl...

In this study we developed a novel methodology based on fish communities to assess the ecological potential of central European reservoirs. Using the hindcasting approach, our index predicts values that could be observed in the absence of pressures for each reservoir depending on their environmental characteristics. Fish data were collected from 144 French and Czech reservoirs between 2005 and 2013 by standardized benthic gillnet sampling and transformed to functional and taxonomical metrics. After all validation by multiple testing of models redundancy and pressure-response, the final index was composed of three metrics: total biomass of fish, abundance of invertivores/piscivores, and abundance of planktivorous fish. The index accurately identifies reservoirs that are lightly, moderately and heavily affected by eutrophication. In addition to French and Czech reservoirs, this index could be a useful tool for countries with few reservoirs and the basis for further collaborative studies.

Ecological effects of alien species can be dramatic, but management and prevention of negative impacts are often hindered by crypticity of the species or their ecological functions. Ecological functions can change dramatically over time, or manifest after long periods of an innocuous presence. Such cryptic processes may lead to an underestimation of long-term impacts and constrain management effectiveness. Here, we present a conceptual framework of crypticity in biological invasions. We identify the underlying mechanisms, provide evidence of their importance, and illustrate this phenomenon with case studies. This framework has potential to improve the recognition of the full risks and impacts of invasive species.

The impact of species loss on ecosystems functioning depends on the amount of trait similarity between species, i.e. functional redundancy, but it is also influenced by the order in which species are lost. Here we investigated redundancy and sensitivity patterns across fish assemblages in lakes, rivers and estuaries. Several scenarios of species extinction were simulated to determine whether the loss of vulnerable species (with high propensity of extinction when facing threats) causes a greater functional alteration than random extinction. Our results indicate that the functional redundancy tended to increase with species richness in lakes and rivers, but not in estuaries. We demonstrated that i) in the three systems, some combinations of functional traits are supported by non-redundant species, ii) rare species in rivers and estuaries support singular functions not shared by dominant species, iii) the loss of vulnerable species can induce greater functional alteration in rivers than in lakes and estuaries. Overall, the functional structure of fish assemblages in rivers is weakly buffered against species extinction because vulnerable species support singular functions. More specifically, a hotspot of functional sensitivity was highlighted in the Iberian Peninsula, which emphasizes the usefulness of quantitative criteria to determine conservation priorities info:eu-repo/semantics/publishedVersion

[Departement_IRSTEA]Eaux [TR1_IRSTEA]QUASARE; International audience; The impact of species loss on ecosystems functioning depends on the amount of trait similarity between species, i.e. functional redundancy, but it is also influenced by the order in which species are lost. Here we investigated redundancy and sensitivity patterns across fish assemblages in lakes, rivers and estuaries. Several scenarios of species extinction were simulated to determine whether the loss ofvulnerable species (with high propensity of extinction when facing threats) causes a greater functional alteration than random extinction. Our results indicate that the functional redundancy tended toincrease with species richness in lakes and rivers, but not in estuaries. We demonstrated that i) in the three systems, some combinations of functional traits are supported by non-redundant species, ii) rarespecies in rivers and estuaries support singular functions not shared by dominant species, iii) the loss of vulnerable species can induce greater functional alteration in rivers than in lakes and estuaries. Overall, the functional structure of fish assemblages in rivers is weakly buffered against species extinction because vulnerable species support singular functions. More specifically, a hotspot of functionalsensitivity was highlighted in the Iberian Peninsula, which emphasizes the usefulness of quantitative criteria to determine conservation priorities.

We examined whether Macrocentrus cingulum (Hymenoptera: Braconidae) of Asian origin could serve as a biological control agent of the maize pest Ostrinia nubilalis (Lepidoptera: Crambidae) in Europe. M. cingulum is already present in Europe, where it does not parasitize O. nubilalis but Ostriniascapulalis, a related species feeding on wild dicotyledons. In contrast, M. cingulum have been imported from Europe and Asia into North America (where O. nubilalis had been accidentally introduced from Europe), and does parasitize O. nubilalis there. We conducted laboratory infestations to assess host acceptability (parasitoid’s propensity to oviposit) and suitability (parasitoid’s ability to develop) of European O. nubilalis for M. cingulum of European and Asian origin, and of Ostriniafurnacalis (their original host) for Asian M. cingulum. Asian M. cingulum parasitized European O. nubilalis as readily as O. furnacalis, and developed equally well in terms of: % female cocoons, time to first emergence from the cocoon, total number of adult offspring, % female offspring and adult longevity. Adult female parasitoids were significantly larger when emerging from O. nubilalis, mixed-sex and male cocoons were significantly more and less frequent, respectively. The acceptability of O. nubilalis was significantly lower for European than for Asian M. cingulum, and its suitability was zero. Asian M. cingulum appears a potential candidate for introduction as a biological control agent of a major maize pest, European O. nubilalis, provided environmental impact studies, economic analyses, and foreseeable interactions with other biological control agents such as the egg parasitoid Trichogramma brassicae (Hymenoptera: Trichogrammatidae) are satisfying.

International audience; In this study we developed a novel methodology based on fish communities to assess the ecological potential of central European reservoirs. Using the hindcasting approach, our index predicts values that could be observed in the absence of pressures for each reservoir depending on their environmental characteristics. Fish data were collected from 144 French and Czech reservoirs between 2005 and 2013 by standardized benthic gillnet sampling and transformed to functional and taxonomical metrics. After all validation by multiple testing of models redundancy and pressure-response, the final index was composed of three metrics: total biomass of fish, abundance of invertivores/piscivores, and abundance of planktivorous fish. The index accurately identifies reservoirs that are lightly, moderately and heavily affected by eutrophication. In addition to French and Czech reservoirs, this index could be a useful tool for countries with few reservoirs and the basis for further collaborative studies.

A community hosted by an ecosystem composed of species sharing the same characteristics i.e. species showing the same response to the environment and/or species with the same impact on their environment, can be define as a community with high functional redundancy. Such community is supposed to be less vulnerable to species loss and the ecosystem functioning is also supposed to be less impacted than when communities are composed of species with different functional characteristics. In this work, we first described the fish communities of lakes, rivers and estuaries of France, Spain and Portugal using species richness and functional diversity. Functional diversity was a measure of the extent of complementary among species considering five characteristics previously define by different sources (literature, available database): fish size, vertical position in the water body, spawning habitat, trophic group, and swimming mode. For the three aquatic systems, the number of species and functional diversity was generally higher in northern and western France than in the Mediterranean areas; this geographical pattern was explained by historical events (last glacial period). Higher functional diversity shown in estuaries compare to lakes and rivers was explained by the importance of the connectivity between adjacent environments. Analysing correlations between functional redundancy and species richness, results suggest that higher taxonomic richness in freshwater ecosystems is likely to increase the stability and resilience of fish assemblages after environmental disturbance because of higher species redundancy whereas it is not the case in estuaries. Studying the impact of species loss according different scenarios, we also demonstrated that, in rivers and estuaries, rare species support singular ecological functions not shared by dominant species. Our results suggest also that functional diversity of fish assemblages in rivers can be more affected by environmental disturbances than in lakes and estuaries. Finally, using functional redundancy and taxonomic vulnerability, we proposed a composite index of functional vulnerability, minimised for highly redundant assemblages composed of species with low extinction risk. Fish communities of estuarine ecosystems appear less vulnerable to species loss in comparison with assemblages of lakes and rivers. Although these latter systems obtained comparable scores, the functional vulnerability was not influenced by the same component. Fish assemblages in lakes are often redundant but composed of a large part of vulnerable species, whereas river assemblages are in general poorly redundant but composed of species with low intrinsic vulnerability. This new score is proposed to be used in conservation perspective to define management priorities.

International audience; Biological indicators are frequently used to assess the effects of anthropogenic stressors on freshwater ecosystems. The structure of fish communities and their response to stressors have been commonly described by taxonomic richness, diversity and evenness. More recently, functional structure of communities has also been suggested to be a reliable indicator of disturbance. This article aimed at testing whether taxonomic and functional diversity metrics can provide comparable or complementary information on the response of fish communities to eutrophication and abundance of non-native species in reservoirs. Comparison of the responses of taxonomic and functional diversities to biogeography, habitat and stressors was made in 112 French reservoirs. Widely observed effects of biogeographic and habitat variables on taxonomic and functional diversities were identified. Taxonomic and functional richness metrics notably increased with lake area and temperature respectively. Taxonomic diversity metrics did not respond to any stressor, while all functional diversity metrics were found to be impacted by non-native species. Eutrophication was further found to decrease the impact of non-native species on two functional diversity metrics: evenness and divergence. Our study therefore reveals that functional metrics are more sensitive than taxonomic metrics to anthropogenic stressors in the studied reservoirs. Still, the multiple linear regressions tested had overall low explanatory power. Further refinements will thus be needed to use this type of metrics in an impact assessment scheme.

International audience; In naturally disturbed systems, harsh environmental conditions act as filters on the regional species pool, restricting the number of taxa able to form a local community to those with traits promoting resistance or resilience. Thus, communities in highly disturbed ecosystems may be less sensitive to a given disturbance than those in less disturbed ecosystems. We explored this idea by examining the response of aquatic invertebrate communities to flow intermittence in gravel-bed, braided rivers (BRs). Flow intermittence is considered a major driver of communities in rivers, but its influence on communities in BRs, which are recognized as naturally highly disturbed environments, is relatively unexplored. We used a multisite Before-After–Control- Impact (BACI) design to quantify the effects of drying events of different durations (moderate: 2–3 wk, severe:1–3 mo) on invertebrate communities in 8 BRs in southeastern France. As predicted, no effects of flow intermittence were detected 1 to 4 mo after flow resumption on taxonomic richness, composition, or functional diversity of communities facing moderate drying events. Communities subjected to severe drying events were similar to those in perennial reaches as few as 19 d after flow resumption. Moreover, communities showed functional redundancy and no loss of functional diversity after drying events. These results differ from those of studies in other river systems, where persistent effects of flow intermittence on communities generally have been found, and highlight the need for cross-system comparisons that explore the effects of drying on communities. Identifying the processes (e.g., niche selection, cotolerance) and habitat features (e.g., hyporheic zone refugia) that promote community resilience in BRs will advance our understanding of how anthropogenic stressors and climate change may affect communities in freshwater ecosystems.

International audience; We reviewed 219 papers and built an inventory of 532 items of ecological evidence on multiple stressor impacts in rivers, lakes, transitional and coastal waters, as well as groundwaters. Our review revealed that, despite the existence of a huge conceptual knowledge base in aquatic ecology, few studies actually provide quantitative evidence on multi-stress effects. Nutrient stress was involved in 71% to 98% of multi-stress situations in the three types of surface water environments, and in 42% of those in groundwaters. However, their impact manifested differently along the groundwater-river-lake-transitional-coastal continuum, mainly determined by the different hydro-morphological features of these ecosystems. The reviewed papers addressed two-stressor combinations most frequently (42%), corresponding with the actual status-quo of pressures acting on European surface waters as reported by the Member States in the WISE WFD Database (EEA, 2015). Across all biological groups analysed, higher explanatory power of the stress-effect models was discernible for lakes under multi-stressor compared to single stressor conditions, but generally lower for coastal and transitional waters. Across all aquatic environments, the explanatory power of stress-effect models for fish increased when multi-stressor conditions were taken into account in the analysis, qualifying this organism group as a useful indicator of multi-stress effects. In contrast, the explanatory power of models using benthic flora decreased under conditions of multiple stress

International audience; We reviewed 219 papers and built an inventory of 532 items of ecological evidence on multiple stressor impacts in rivers, lakes, transitional and coastal waters, as well as groundwaters. Our review revealed that, despite the existence of a huge conceptual knowledge base in aquatic ecology, few studies actually provide quantitative evidence on multi-stress effects. Nutrient stress was involved in 71% to 98% of multi-stress situations in the three types of surface water environments, and in 42% of those in groundwaters. However, their impact manifested differently along the groundwater-river-lake-transitional-coastal continuum, mainly determined by the different hydro-morphological features of these ecosystems. The reviewed papers addressed two-stressor combinations most frequently (42%), corresponding with the actual status-quo of pressures acting on European surface waters as reported by the Member States in the WISE WFD Database (EEA, 2015). Across all biological groups analysed, higher explanatory power of the stress-effect models was discernible for lakes under multi-stressor compared to single stressor conditions, but generally lower for coastal and transitional waters. Across all aquatic environments, the explanatory power of stress-effect models for fish increased when multi-stressor conditions were taken into account in the analysis, qualifying this organism group as a useful indicator of multi-stress effects. In contrast, the explanatory power of models using benthic flora decreased under conditions of multiple stress

International audience; Multiple anthropogenic pressures including the widespread introductions of non‐native species threaten biodiversity and ecosystem functioning notably by modifying the trophic structure of communities. Here, we provided a global evaluation of the impacts of non‐native species on the isotopic structure (δ13C and δ15N) of freshwater fish communities. We gathered the stable isotope values (n = 4030) of fish species in 496 fish communities in lentic (lakes, backwaters, reservoirs) and lotic (running waters such as streams, rivers) ecosystems throughout the world and quantified the isotopic structure of communities. Overall, we found that communities containing non‐native species had a different isotopic structure than communities without non‐native species. However, these differences varied between ecosystem types and the trophic positions of non‐native species. In lotic ecosystems, communities containing non‐native species had a larger total isotopic niche than communities without non‐native species. This was primarily driven by the addition of non‐native predators at the top of the food chain that increased δ15N range without modifying the isotopic niche size of native species. In lentic ecosystems, non‐native primary consumers increased δ15N range and this was likely driven by an increase of resource availability for species at higher trophic levels, increasing food chain length. The introduction of non‐native secondary consumers at the centre of the isotopic niche of recipient communities decreased the core isotopic niche size, the δ13C range of recipient communities and the total isotopic niche of coexisting native species. These results suggested a modified contribution of the basal resources consumed (e.g. multi‐chain omnivory) and an increase level of competition with native species. Our results notably imply that, by affecting the isotopic structure of freshwater fish communities at a global scale, non‐native species represent an important source of perturbations that should be accounted for when investigating macro‐ecological patterns of community structure and biotic interactions.

International audience; We reviewed 219 papers and built an inventory of 532 items of ecological evidence on multiple stressor impacts in rivers, lakes, transitional and coastal waters, as well as groundwaters. Our review revealed that, despite the existence of a huge conceptual knowledge base in aquatic ecology, few studies actually provide quantitative evidence on multi-stress effects. Nutrient stress was involved in 71% to 98% of multi-stress situations in the three types of surface water environments, and in 42% of those in groundwaters. However, their impact manifested differently along the groundwater-river-lake-transitional-coastal continuum, mainly determined by the different hydro-morphological features of these ecosystems. The reviewed papers addressed two-stressor combinations most frequently (42%), corresponding with the actual status-quo of pressures acting on European surface waters as reported by the Member States in the WISE WFD Database (EEA, 2015). Across all biological groups analysed, higher explanatory power of the stress-effect models was discernible for lakes under multi-stressor compared to single stressor conditions, but generally lower for coastal and transitional waters. Across all aquatic environments, the explanatory power of stress-effect models for fish increased when multi-stressor conditions were taken into account in the analysis, qualifying this organism group as a useful indicator of multi-stress effects. In contrast, the explanatory power of models using benthic flora decreased under conditions of multiple stress

Aquatic ecosystems facing multiple stressors lead to challenging conditions for their management, as stressors can have additive, but also interactive effects on organisms, populations and communities. Accounting for these interactions is important in the assessment of the stressor’s impacts and to implement good restoration measures. Using a comparable modelling approach and large environmental and fish databases, the combined effect of water quality problems and hydrological stressors were assessed, based on characteristics of fish assemblages observed in rivers, lakes, reservoirs and estuaries of Europe. The effects of nonnative species in interaction with eutrophication and alteration of hydromorphology were also tested for fish assemblages of natural lakes and reservoirs. We show that for all the water body types, water quality problems are a major threat that impacts fish assemblages. Similarly, alteration of the hydro-morphology explains a large part of the composition of river and estuarine fish assemblages. Conversely, we fail to demonstrate an effect of this stressor on the fish community of lakes and reservoirs, as sufficient data are not available yet. However, in these standing waters the introduction of non-native species can explain the variability of some characteristics of fish assemblages. In a second step, we analysed the interactive effect of various stressors. Without interaction, the effect of two stressors on a fish assemblage characteristic corresponds to the sum of the individual effects. This additive effect was compared with the effects really observed in the assemblages to determine the type of interaction. The comparison was done for each fish assemblage characteristic impacted by stressors in each water body type. A large variability of multi-stressor impacts was observed, leading to higher or lower effects than expected in absence of interactions. These results suggest to consider all potential stressors and interactions in the development of fishbased tools dedicated to ecological status assessment or restoration monitoring whatever the water body type is.

Aquatic ecosystems facing multiple stressors lead to challenging conditions for their management, as stressors can have additive, but also interactive effects on organisms, populations and communities. Accounting for these interactions is important in the assessment of the stressor’s impacts and to implement good restoration measures. Using a comparable modelling approach and large environmental and fish databases, the combined effect of water quality problems and hydrological stressors were assessed, based on characteristics of fish assemblages observed in rivers, lakes, reservoirs and estuaries of Europe. The effects of nonnative species in interaction with eutrophication and alteration of hydromorphology were also tested for fish assemblages of natural lakes and reservoirs. We show that for all the water body types, water quality problems are a major threat that impacts fish assemblages. Similarly, alteration of the hydro-morphology explains a large part of the composition of river and estuarine fish assemblages. Conversely, we fail to demonstrate an effect of this stressor on the fish community of lakes and reservoirs, as sufficient data are not available yet. However, in these standing waters the introduction of non-native species can explain the variability of some characteristics of fish assemblages. In a second step, we analysed the interactive effect of various stressors. Without interaction, the effect of two stressors on a fish assemblage characteristic corresponds to the sum of the individual effects. This additive effect was compared with the effects really observed in the assemblages to determine the type of interaction. The comparison was done for each fish assemblage characteristic impacted by stressors in each water body type. A large variability of multi-stressor impacts was observed, leading to higher or lower effects than expected in absence of interactions. These results suggest to consider all potential stressors and interactions in the development of fishbased tools dedicated to ecological status assessment or restoration monitoring whatever the water body type is.

Robotics provides answers to amputees. The most expensive solutions surgically connect the prosthesis to nerve endings. There are also several types of non-invasive technologies that recover nerve messages passing through the muscles. After analyzing these messages, myoelectric prostheses perform the desired movement. The main goal is to avoid all surgeries, which can be heavy and offer cheaper alternatives. For an amputee, we use valid muscles to recover the electrical signal involved in a muscle movement. EMG sensors placed on the muscle allows us to measure a potential difference, which our program transforms into control for a robotic arm with two degrees of freedom. We have shown the feasibility of non-invasive prostheses with two degrees of freedom. Signal analysis and an increase in degrees of freedom is still being improved., {"references":["Gnahoua Zoabli, Institut de génie Biomédical, Faculté de médecine de\nMontréal, Thèse : Imagerie des muscles du membre supérieur et du dos,\ndécembre 2005.","M. Atieh, P. Y. Glorennec, C. Nasr: Commande myoélectrique d'une\nprothèse de main communicante et « intelligente », 4th International\nConference: Sciences of Electronic, Technologies of Information and\nTelecommunications, March 25-29, 2007.","Pascale Thousalin-Chretien, Université de Strasbourg, Ecole Doctoral\ndes Sciences de la Vie et de la Santé, Thèse: Etude des liens entres les\nsystèmes visuel et proprioceptif : approche électrophysiologique et\ncomportementale chez le sujet sain et le patient amputé du membre\nsupérieur. Journal of Cognitive Neuroscience, 2009, vol. 21, n° 11,\nPages 2207-2216.","T. A. Kuiken, G. A. Dumanian, R.D. Lipschutz, L.A. Miller, K.A.\nStubbllefield: The use of targeted muscle reinnervation for improved\nmyoelectric prosthesis control in a bilateral shoulder disarticulation\namputee, Prosthetics and Orthotics International, 2004.28.245-253.","Todd A. Kuiken, Guanglin Li, Blair A. Lock, Robert D. Lipschutz,\nLaura A. Miller, Kathy A. Stubblefield, Kevin B. Englehart, :Targeted\nMuscle Reinnervation for Real-time Myoelectric Control of\nMultifunction Artificial Arms, American Medical Association, 2009.","Lionel Rousseau, Université de Paris Est, Thèse : Développement de\nnouvelles matrices de microélectrodes pour l'analyse et la\ncompréhension du système nerveux central, directeur de Thèse Prof;\nGaëlle LISSORGUES, 13 janvier 2010.","Muhammad Zahak Jamal: Signal Acquisition Using Surface EMG and\nCircuit Design Considerations for Robotic Prosthesis, National University of Sciences and Technology, Pakistan. Book:\n\"Computational Intelligence in Electromyography Analysis - A\nPerspective on Current Applications and Future Challenges\", October\n17, 2012.","Erik Scheme, MSc, PEng; Kevin Englehart, PhD, PEng :\nElectromyogram pattern recognition for control of powered upper-limb\nprostheses: State of the art and challenges for clinical use, Journal of\nRehabilitation Research & Development, Volume 48 Number 6,Pages\n643 — 660, 2011.","Bart Peerdeman, MSc; Daphne Boere, MSc; Heidi Witteveen, MSc;\nRianne Huis in `t Veld, PhD; Hermie Hermens, PhD; Stefano\nStramigioli, PhD; HansRietman, MD, PhD; Peter Veltink, PhD; Sarthak\nMisra, PhD, Myoelectric forearm prostheses: State of the art from a\nuser-centered perspective, Journal of Rehabilitation Research &\nDevelopment, Volume 48 Number 6, Pages 719 — 738, 2011.\n[10] Hanneke Bouwsema, MSc; Peter J. Kyberd, PhD; Wendy Hill, BScOT;\nCorry K. van der Sluis, MD, PhD; Raoul M. Bongers, PhD: Determining\nskill level in myoelectric prosthesis use with multiple outcome measures,\nJournal of Rehabilitation Research & Development, Volume 49,\nNumber 9, 2012, Pages 1331—1348.\n[11] S. G. Millstein, H. Heger and G. A. Hunter: Prosthetic use in adult upper\nlimb amputees: a comparison of the body powered and electrically\npowered prostheses, Prosthetics and Orthotics International. 1986, 10,\n27-34 .\n[12] Hanna Heger. Sandra Millstein,Gordon A. Hunter: Electrically Powered\nProstheses for the Adult with an Upper Limb Amputation, J Bone Joint\nSurg Br March 1985 vol. 67-B no. 2 278-281.\n[13] Martin Lotze, Herta Flor, Wolfgang Grodd, Wolfgang Larbig and Niels\nBirbaumer: Phantom movements and pain An fMRI study in upper limb\namputees, Brain ,2001 - Oxford Univ Press."]}