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Beavers and their dams, once common in small streams throughout Eurasia and North America, are returning to their original range. Beaver dams are special habitats in the aquatic-terrestrial interface, but their macroinvertebrate fauna is hardly known. This study aims to qualify and quantify the invertebrate fauna of beaver dams, taking into account the maintenance status of the dams. Nine different areas covering the top, middle and base zones of eight maintained and eight abandoned beaver dams were sampled using a specially designed suction device. The invertebrate community of beaver dams proved to be diverse and predominantly rheophilic. Community composition reflects higher flow velocities in streamside habitats; this gradient is more pronounced in maintained than in abandoned dams. Shredders are the most abundant feeding type, but they are less frequent in streamside habitats, in particular in those of maintained dams, where passive filter feeders prevail. Terrestrial/Semiaquatic taxa colonising hygropetric areas were found in streamside habitats especially of abandoned dams. Our results underline that beaver dams provide a wide variety of environmental conditions and habitat types, which enhance biodiversity in small streams and their floodplains. Beaver dams in riverine landscapes should therefore be much more valued in floodplain conservation and management.

The scientific community is deeply concerned about the ongoing discussions on the EU’s Green Deal. Of particular concern are the current criticisms targeting the Sustainable Use Regulation (SUR) and Nature Restoration Law (NRL). We urge policy makers to continue the legislative procedure for the SUR and the NRL, and invite opponents of the Green Deal for a consultation with scientists. The call was led by 17 scientists and signed by 3,339 scientists across EU Member States and 17 additional countries.

Woody riparian vegetation (WRV) benefits benthic macroinvertebrates in running waters. However, while some functions are provided by WRV irrespective of surrounding and catchment land use, others are context-specific. In recent large-scale studies, effects of WRV on macroinvertebrates were therefore small compared to catchment land use, raising the question about the relevance of WRV for restoration. Model-based recursive partitioning was used to identify context-dependent effects of WRV on the macroinvertebrates' ecological status in small (catchment area 10–100 km²) lowland (n = 361) and mountain (n = 748) streams. WRV cover was quantified from orthophotos along the near (500 m) and far (5000 m) upstream river network and used to predict the site's ecological status. Agricultural, urban and woodland cover at the local and catchment scales along with hydromorphology were considered as partitioning variables. In rural agricultural landscapes, the effect of WRV on the ecological status was large, indicating that establishing near-upstream WRV can improve the ecological status by as much as two of the five classes according to the EU Water Framework Directive. Even in urban landscapes, effects of far-upstream WRV were large if catchments had a moderate share of agricultural land use in addition. The beneficial effects of WRV were only limited in purely urban catchments or in a multiple stressor context. Synthesis and applications. While woody riparian vegetation (WRV) can even improve the ecological status in urban settings, it is especially relevant for river management in rural agricultural catchments, where developing WRV potentially are effective measures to achieve good ecological status.

Agriculture, the world’s most dominant land use type, burdens freshwater biodiversity with a multitude of stressors such as diffuse pollution and hydromorphological alteration. However, it is difficult to directly link agricultural land use with biota response as agricultural stressors can also originate from other causes. Also, there is evidence for positive and negative effects of agriculture on organisms, agricultural impact differs strongly with the biological metric and study region considered and agricultural impact differs among practice and type, which in turn affects different organism groups with varying severity. Against this background, our study aimed at assessing, if agricultural land use has a consistent effect on river biota. We conducted a systematic review of the literature, which yielded 43 studies and 76 relationships between agriculture and aquatic organism groups. The relationships were subjected to a meta-analysis using Hedge’s g to calculate the standardized mean difference of effects. Overall, we detected a medium to strong effect g = − 0.74 of agricultural land use on freshwater biota, only marginally influenced by study design, river type and region. Strong differences in biota response could be observed depending on the biological metric assessed, with ecological quality indices of agricultural impairment performing best. Sensitive taxa declined with agricultural impact, while tolerant taxa tended to benefit. In addition, the biota response differed among agricultural types and practices and organism group, with macroinvertebrates showing the strongest effect. Our results quantify the effects of agriculture on riverine biota and suggest biological metric types for assessing agricultural impact. Further research is needed to discriminate between agricultural types and account for intensity.

Robust demonstration case-studies are needed to evaluatewhether improvements in ecosystem condition are translated into improvements in ecosystem services. This research is essential for effectively scaling-up nature-based solutions across Europe and providing the evidence to support transformation agendas in society and industries, and ultimately supporting the ambitions of the European Green Deal. Clear guidance and standardised indicators help monitor the impact of freshwater and wetland restoration measures on European Green Deal goals. These monitoring indicators should include environmental indicators (e.g. for biodiversity, greenhouse gas emissions and water storage capacity) as well as socio-economic indicators such as stakeholder representation, private finance mobilisation and job creation. A combined Before-After-Control-Intervention (BACI) monitoring design is recommended to provide robust evidence and attribute change to the restoration measures. Benchmark (cost or effort) and local/regional context data (e.g. land use, governance) are also needed alongside monitoring of impacts to not just measurewhathas happened at a site but to understandwhyit has happened. &nbsp

Woody riparian vegetation (WRV) benefits benthic macroinvertebrates. However, in recent large scale studies, the effects of WRV on macroinvertebrates were small compared to catchment landuse, raising the question about the relevance of WRV in restoration. Limited effects of WRV might be due to context specificity: While some functions are provided by WRV irrespective of catchment landuse, others depend on the landscape setting.Recursive partitioning modelling was used to identify context dependent effects of WRV on streams macroinvertebrates’ ecological status in small lowland (n = 361) and mountain streams (n = 748). WRV cover was quantified from orthophotos along the near (500 m) and far (5,000 m) upstream river network and used to predict the site’s ecological status. Agricultural, urban and woodland cover at the local and catchment scales along with hydromorphology were considered as partitioning variables.In rural agricultural landscapes, the effect of WRV on the ecological status was large, indicating that establishing WRV can improve the ecological status by as much as two classes.In streams impacted by catchment urbanization, effects of WRV were largest, but WRV cover and ecological status were both low, indicating practical limitations of WRV restoration in urban catchments.Synthesis and applications: Independent effects of WRV on macroinvertebrates’ ecological status can be discerned from catchment landuse. While WRV can also improve the ecological status in urban settings, it is especially relevant for river management in rural agricultural catchments, where developing WRV potentially are effective measures to reach good ecological status

Multiple stressors are continuously deteriorating surface waters worldwide, posing many challenges for their conservation and restoration. Combined effect types of multiple stressors range from single-stressor dominance to complex interactions. Identifying prevalent combined effect types is critical for environmental management, as it helps to prioritise key stressors for mitigation. However, it remains unclear whether observed single and combined stressor effects reflect true ecological processes unbiased by sample size and length of stressor gradients. Therefore, we examined the role of sample size and stressor gradient lengths in 158 paired-stressor response cases with over 120,000 samples from rivers, lakes, transitional and marine ecosystems around the world. For each case, we split the overall stressor gradient into two partial gradients (lower and upper) and investigated associated changes in single and combined stressor effects. Sample size influenced the identified combined effect types, and stressor interactions were less likely for cases with fewer samples. After splitting gradients, 40 % of cases showed a change in combined effect type, 30 % no change, and 31 % showed a loss in stressor effects. These findings suggest that identified combined effect types may often be statistical artefacts rather than representing ecological processes. In 58 % of cases, we observed changes in stressor effect directions after the gradient split, suggesting unimodal stressor effects. In general, such non-linear responses were more pronounced for organisms at higher trophic levels. We conclude that observed multiple stressor effects are not solely determined by ecological processes, but also strongly depend on sampling design. Observed effects are likely to change when sample size and/or gradient length are modified. Our study highlights the need for improved monitoring programmes with sufficient sample size and stressor gradient coverage. Our findings emphasize the importance of adaptive management, as stress reduction measures or further ecosystem degradation may change multiple stressor-effect relationships, which will then require associated changes in management strategies. Scenarios of Biodiversity and Ecosystem Services II programme, jointly supported by Belmont Forum, Biodiversa and the European Commission; Deutsche Forschungsgemeinschaft; Fénix Programme, Government of Cantabria; Augusto González de Linares, Programa de ayudas de la Universidad de Cantabria para contratos posdoctorales, grant number: POS-UC-2020-07; Environmental Protection Agency (Ireland); Marine Institute (Ireland); Basque Water Agency (URA) and Consorcio de Aguas Bilbao-Bizkaia (Spain); Cawthron Institute, New Zealand; Ministry for the Environment, New Zealand; Oranga Taiao Oranga Tangata research programme, New Zealand Ministry of Business, Innovation and Employment grant number MAUX1502; The project FRESHABIT LIFE IP (LIFE14/IPE/FI/023); USA National Science Foundation, Dimensions of Biodiversity Program (1831096); Irish Research Council Laureate Award (IRCLA/2017/112).

The growing use of functional traits in ecological research has brought new insights into biodiversity responses to global environmental change. However, further progress depends on overcoming three major challenges involving (a) statistical correlations between traits, (b) phylogenetic constraints on the combination of traits possessed by any single species, and (c) spatial effects on trait structure and trait–environment relationships. Here, we introduce a new framework for quantifying trait correlations, phylogenetic constraints and spatial variability at large scales by combining openly available species’ trait, occurrence and phylogenetic data with gridded, high‐resolution environmental layers and computational modelling. Our approach is suitable for use among a wide range of taxonomic groups inhabiting terrestrial, marine and freshwater habitats. We demonstrate its application using freshwater macroinvertebrate data from 35 countries in Europe. We identified a subset of available macroinvertebrate traits, corresponding to a life‐history model with axes of resistance, resilience and resource use, as relatively unaffected by correlations and phylogenetic constraints. Trait structure responded more consistently to environmental variation than taxonomic structure, regardless of location. A re‐analysis of existing data on macroinvertebrate communities of European alpine streams supported this conclusion, and demonstrated that occurrence‐based functional diversity indices are highly sensitive to the traits included in their calculation. Overall, our findings suggest that the search for quantitative trait–environment relationships using single traits or simple combinations of multiple traits is unlikely to be productive. Instead, there is a need to embrace the value of conceptual frameworks linking community responses to environmental change via traits which correspond to the axes of life‐history models. Through a novel integration of tools and databases, our flexible framework can address this need.

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation. ispartof: ECOLOGY LETTERS vol:25 issue:2 pages:255-263 ispartof: location:England status: published

Identifying novel pathways regulating the adaptive immune response in chronic inflammatory diseases such as atherosclerosis is of particular interest in view of developing new therapeutic drugs. Here we report that the lipid receptor GPR55 is highly expressed by splenic B cells and inversely correlates with atheroma plaque size in mice. In human carotid endarterectomy specimen, GPR55 transcript levels were significantly lower in unstable compared to stable carotid plaques. To study the impact of GPR55 deficiency in atherosclerosis, we crossedGpr55knockout mice with apolipoprotein E (ApoE) knockout mice and subjected the mice to Western diet for 4 to 16 weeks. Compared toApoE-/-controls,ApoE-/-Gpr55-/-mice developed larger plaques with increased necrotic core size, associated with elevated circulating and aortic leukocyte counts. Flow cytometry, immunofluorescence and RNA-sequencing analysis of splenic B cells in these mice revealed a hyperactivated B cell phenotype with disturbed plasma cell maturation and immunoglobulin (Ig)G antibody overproduction. The specific contribution of B cell GPR55 in atherosclerosis was further studied in mixedGpr55-/-/µMTbone marrow chimeras on low density receptor deficiency (Ldlr-/-) background, revealing that B-cell specific depletion ofGpr55was sufficient to promote plaque development. Conversely, adoptive transfer of wildtype B cells intoApoE-/-Gpr55-/-mice blunted the proatherogenic phenotype.In vitrostimulation of splenocytes with the endogenous GPR55 ligand LPI promoted plasma cell proliferation and enhanced B cell activation marker expression, which was inhibited by the GPR55 antagonist CID16020046. Collectively, these discoveries provide new evidence for GPR55 as key modulator of the adaptive immune response in atherosclerosis. Targeting GPR55 could be useful to limit inflammation and plaque progression in patients suffering from atherosclerosis.

International audience; La végétation riveraine ligneuse le long des rivières et des ruisseaux remplit de multiples fonctions bénéfiques pour les communautés de macroinvertébrés aquatiques . Ils retiennent les sédiments fins, les nutriments et les pesticides, améliorent l'hydromorphologie des canaux, contrôlent la température de l'eau et la production primaire grâce à l'ombrage et fournissent des feuilles, des brindilles et du gros bois.Dans un modèle conceptuel récent (Feld et al., 2018), les fonctions riveraines ligneuses ont été considérées soit comme indépendantes des facteurs de stress liés à l'utilisation des terres à grande échelle (p. rétention des nutriments et des pesticides).Nous avons testé ce concept en utilisant des données à haute résolution sur la couverture végétale riveraine ligneuse et des données empiriques provenant de 1017 sites d'échantillonnage de macroinvertébrés dans les ruisseaux de plaine et de montagne allemands. Les métriques des macroinvertébrés indicatives des fonctions individuelles ont été utilisées comme variables de réponse dans les modèles d'équations structurelles (SEM), représentant la structure hiérarchique entre les différents facteurs de stress considérés à différentes échelles spatiales : bassin versant, riverain en amont, riverain local et occupation du sol locale ainsi que l'hydromorphologie et la qualité de l'eau .L'analyse n'a confirmé que partiellement le modèle conceptuel : l' intégrité biotique et la qualité de l'eau étaient fortement liées aux facteurs de stress à grande échelle comme prévu (effet total absolu de 0,345 à 0,541), mais contre les attentes, la rétention de sédiments fins, considérée comme dépendant de l'échelle dans le modèle conceptuel, a été mal expliquée par les facteurs de stress à grande échelle (effet total absolu 0,027-0,231). Alors que la plupart des fonctions considérées comme indépendantes de l'utilisation des terres à grande échelle s'expliquaient en partie par l'occupation des sols riveraine (effet total absolu 0,023–0,091), elles étaient néanmoins également affectées par l'occupation des sols du bassin versant (effet total absolu 0,017–0,390).Alors que de nombreuses études de cas empiriques à des échelles spatiales plus petites documentent clairement les effets positifs de la restauration de la végétation riveraine ligneuse, nos résultats suggèrent que la plupart des effets de la couverture d'utilisation des terres riveraines sont peut-être superposés par des facteurs de stress à plus grande échelle. Cela n'annule pas les effets localisés de la végétation riveraine ligneuse, mais aide à contextualiser les limites des mesures de restauration réussies ciblant la communauté de macroinvertébrés.

Floodplains are inhabited by diverse and abundant ground beetle assemblages that are adapted to the frequently changing habitat conditions. While there have been many studies on the composition of riparian ground beetle communities in individual floodplains, the general patterns responsible for their composition remained obscure. We used data on 352 ground beetle samples taken at 224 sites along rivers and their floodplains in Germany to analyse how natural large-scale descriptors and floodplain morphological status (near-natural vs. degraded vs. restored sites) determine the composition of ground beetle assemblages. For each site we compiled data on region, slope and dominant floodplain substrate, and on floodplain morphological status (near-natural, degraded or restored conditions). Hierarchical clustering revealed eight main clades and a clear hierarchy of parameters, with floodplain slope being responsible for the two main clades, followed by ‘region’ and ‘dominant floodplain substrate’ that structure the second and third orders of division. Some of the third-order clades are exclusively or predominantly composed of near-natural or restored sites, indicating that sites of high morphological status are inhabit by a distinct ground beetle community in a given region. Indicator species analysis resulted in indicators for all regions (132 indicators species) and slope (122 indicator species) categories and for almost all classes of dominant floodplain substrate (117 indicator species). Most of the indicator species with high predictive values and sensitivities belong to the genus Bembidion. For the morphological status categories, we identified 126 indicator species in total: 112 related to near-natural conditions, 13 for restored sites and only a single species for degraded conditions. Our results underline that slope, region and dominant floodplain substrate are among the main natural drivers of riparian ground beetle community composition and the suitability of ground beetles to indicate degradation and restoration processes.

DNA-based methods are at the edge of being implemented into routine monitoring systems. WG5 aimed to develop implementation options for DNA-based methods under a range of environmental directives and legal frameworks, in particular the Water Framework Directive (WFD), the EU Marine Strategy Framework Directive, the UN SDGs, the Global Biodiversity Assessment under the IPBES, the CBD Nagoya Protocol on Access and Benefit Sharing, the digital sequence information on genetic resources (DSI), the Biodiversity Indicator Partnership, and the Essential Biodiversity Variables. It further aimed at starting the standardisation process for DNA-based methods. In the talk, we will give an overview of all WG5 activities, with a focus on the options to use DNA-based methods for the implementation of the WFD. Overall, suitability of DNA-based identification is particularly high for fish, as eDNA is a well-suited sampling approach which can replace expensive and potentially harmful methods. For invertebrates and phytobenthos, the main challenges include the modification of indices and completing barcode libraries. For phytoplankton, the barcode libraries are even more problematic, due to the high taxonomic diversity in plankton samples. If current assessment concepts are kept, DNA-based identification is least appropriate for macrophytes (rivers, lakes) and angiosperms/macroalgae (transitional and coastal waters), which are surveyed rather than sampled. We discuss the challenges and opportunities of implementing DNA-based identification into standard ecological assessment, in particular considering any adaptations to existing legislation that may be required to facilitate the transition to using molecular data.

Nitrogen and phosphorous concentrations are widely considered to drive macrophyte assemblages in rivers. However, Dissolved Inorganic Carbon (DIC) - available for plants as CO2 and HCO3- - is also of major relevance. Based on literature, we present a conceptual model on the interaction between algae, macrophytes, DIC, pH, light, N, P and the surface water and sedimental compartment. Analysing two separate datasets (i) on river physico-chemistry and chlorophyll-a, and (ii) on river physico-chemistry and macrophytes we quantify three connections within this concept: (1) the correlation of chlorophyll-a versus pH, (2) the correlation of TP versus chlorophyll-a and (3) the occurrence of HCO3-users and CO2-only-users among macrophytes along the DIC gradient. Chlorophyll-a correlated positively with pH (R-squared = 77%, p < .001) due to increased carbon dioxide uptake of phytoplankton. Surface water TP did not linearly correlate with chlorophyll-a concentrations. Obligate and optionally submerged macrophyte species that utilise HCO3- were separated from CO2-only-users by HCO3- concentrations, with an area under the curve (AUC) of 68% and 70% (both p < .001) between groups. Obligate and optionally submerged macrophyte assemblages only composed of HCO3-users and those exclusively composed of CO2-only-users showed an even stronger separation based on the HCO3- concentration, with both an AUC of 82% and 78% (both p < .001). Our results underline that DIC can greatly affect riverine macrophytes. However, absolute concentrations of HCO3- are less relevant, while the connection to pH is more important, reflecting CO2 concentrations. River monitoring and management should consider the interaction between nutrients DIC, surface water and sedimental compartment as important factors affecting macrophyte occurrence, rather than solely focussing on surface water nutrients.

A recent global meta‐analysis reported a decrease in terrestrial but increase in freshwater insect abundance and biomass (van Klink et al., Science 368, p. 417). The authors suggested that water quality has been improving, thereby challenging recent reports documenting drastic global declines in freshwater biodiversity. We raise two major concerns with the meta‐analysis and suggest that these account for the discrepancy with the declines reported elsewhere. First, total abundance and biomass alone are poor indicators of the status of freshwater insect assemblages, and the observed differences may well have been driven by the replacement of sensitive species with tolerant ones. Second, many of the datasets poorly represent global trends and reflect responses to local conditions or nonrandom site selection. We conclude that the results of the meta‐analysis should not be considered indicative of an overall improvement in the condition of freshwater ecosystems. This article is categorized under: Water and Life > Conservation, Management, and Awareness, Relying on abundance or biomass and examining nonrepresentative datasets limits our ability to infer the condition of freshwater insect communities globally. Photo by Jeremy Monroe, Freshwaters Illustrated: a caddisfly larva from an Oregon Coastal stream, USA (Limnephilidae: Dicosmoecus sp.)., Federal Agency for Nature Conservation (BfN) http://dx.doi.org/10.13039/100010606, NSF Macrosystems Biology Program, Leibniz‐Gemeinschaft http://dx.doi.org/10.13039/501100001664

The biota of European rivers are affected by a wide range of stressors impairing water quality and hydro-morphology. Only about 40% of Europe's rivers reach 'good ecological status', a target set by the European Water Framework Directive (WFD) and indicated by the biota. It is yet unknown how the different stressors in concert impact ecological status and how the relationship between stressors and status differs between river types. We linked the intensity of seven stressors to recently measured ecological status data for more than 50,000 sub-catchment units (covering almost 80% of Europe's surface area), which were distributed among 12 broad river types. Stressor data were either derived from remote sensing data (extent of urban and agricultural land use in the riparian zone) or modelled (alteration of mean annual flow and of base flow, total phosphorous load, total nitrogen load and mixture toxic pressure, a composite metric for toxic substances), while data on ecological status were taken from national statutory reporting of the second WFD River Basin Management Plans for the years 2010-2015. We used Boosted Regression Trees to link ecological status to stressor intensities. The stressors explained on average 61% of deviance in ecological status for the 12 individual river types, with all seven stressors contributing considerably to this explanation. On average, 39.4% of the deviance was explained by altered hydro-morphology (morphology: 23.2%; hydrology: 16.2%), 34.4% by nutrient enrichment and 26.2% by toxic substances. More than half of the total deviance was explained by stressor interaction, with nutrient enrichment and toxic substances interacting most frequently and strongly. Our results underline that the biota of all European river types are determined by co-occurring and interacting multiple stressors, lending support to the conclusion that fundamental management strategies at the catchment scale are required to reach the ambitious objective of good ecological status of surface waters.

Water temperature is a key driver for riverine biota and strongly depends on shading by woody riparian vegetation in summer. While the general effects of shading on daily maximum water temperature Tmₐₓ are well understood, knowledge gaps on the role of the spatial configuration still exist. In this study, the effect of riparian buffer length, width, and canopy cover (percentage of buffer area covered by woody vegetation) on Tmₐₓ was investigated during summer baseflow using data measured in seven small lowland streams in western Germany (wetted width 0.8–3.7 m). The effect of buffer length on Tmₐₓ differed between downstream cooling and heating: Tmₐₓ approached cooler equilibrium conditions after a distance of 0.4 km (~45 min travel-time) downstream of a sharp increase in canopy cover. In contrast, Tmₐₓ continued to rise downstream of a sharp decrease in canopy cover along the whole 1.6 km stream length investigated. The effect of woody vegetation on Tmₐₓ depended on buffer width, with changes in canopy cover in a 10 m wide buffer being a better predictor for changes in Tmₐₓ compared to a 30 m buffer. The effect of woody vegetation on Tmₐₓ was linearly related to canopy cover but also depended on daily temperature range Trₐngₑ, which itself was governed by cloudiness, upstream canopy cover, and season. The derived empirical relationship indicated that Tmₐₓ was reduced by −4.6°C and increased by +2.7°C downstream of a change from unshaded to fully shaded conditions and vice versa. This maximum effect was predicted for a 10 m wide buffer at sunny days in early summer, in streams with large diel fluctuations (large Trₐngₑ). Therefore, even narrow woody riparian buffers may substantially reduce the increase in Tmₐₓ due to climate change, especially in small shallow headwater streams with low baseflow discharge and large daily temperature fluctuations.

Although experiences with ecological restoration continue to accumulate, the effectiveness of restoration for biota remains debated. We complemented a traditional taxonomic analysis approach with information on 56 species traits to uncover the responses of 3 aquatic (fish, macroinvertebrates, macrophytes) and 2 terrestrial (carabid beetles, floodplain vegetation) biotic groups to 43 hydromorphological river restoration projects in Germany. All taxonomic groups responded positively to restoration, as shown by increased taxonomic richness (10-164%) and trait diversity (habitat, dispersal and mobility, size, form, life history, and feeding groups) (15-120%). Responses, however, were stronger for terrestrial than aquatic biota, and, contrary to our expectation, taxonomic responses were stronger than those of traits. Nevertheless, trait analysis provided mechanistic insights into the drivers of community change following restoration. Trait analysis for terrestrial biota indicated restoration success was likely enhanced by lateral connectivity and reestablishment of dynamic processes in the floodplain. The weaker response of aquatic biota suggests recovery was hindered by the persistence of stressors in the aquatic environment, such as degraded water quality, dispersal constraints, and insufficient hydromorphological change. Therefore, river restoration requires combined local- and regional-scale approaches to maximize the response of both aquatic and terrestrial organisms. Due to the contrasting responses of aquatic and terrestrial biota, the planning and assessment of river restoration outcomes should consider effects on both components of riverine landscapes.

To meet the United Nations (UN) sustainable development goals and the European Union (EU) strategy for a non-toxic environment, water resources and ecosystems management require cost-efficient solutions for prevailing complex contamination and multiple stressor exposures. For the protection of water resources under global change conditions, specific research needs for prediction, monitoring, assessment and abatement of multiple stressors emerge with respect to maintaining human needs, biodiversity, and ecosystem services. Collaborative European research seems an ideal instrument to mobilize the required transdisciplinary scientific support and tackle the large-scale dimension and develop options required for implementation of European policies. Calls for research on minimizing society’s chemical footprints in the water–food–energy–security nexus are required. European research should be complemented with targeted national scientific funding to address specific transformation pathways and support the evaluation, demonstration and implementation of novel approaches on regional scales. The foreseeable pressure developments due to demographic, economic and climate changes require solution-oriented thinking, focusing on the assessment of sustainable abatement options and transformation pathways rather than on status evaluation. Stakeholder involvement is a key success factor in collaborative projects as it allows capturing added value, to address other levels of complexity, and find smarter solutions by synthesizing scientific evidence, integrating governance issues, and addressing transition pathways. This increases the chances of closing the value chain by implementing novel solutions. For the water quality topic, the interacting European collaborative projects SOLUTIONS, MARS and GLOBAQUA and the NORMAN network provide best practice examples for successful applied collaborative research including multi-stakeholder involvement. They provided innovative conceptual, modelling and instrumental options for future monitoring and management of chemical mixtures and multiple stressors in European water resources. Advancement of EU water framework directive-related policies has therefore become an option. © 2019, The Author(s)., Funding text #1 This article has been prepared as an outcome of the projects SOLUTIONS (European Union’s Seventh Framework Programme for research, technological development and demonstration under Grant Agreement No. 603437), GLOBAQUA (European Union’s Seventh Framework Programme for research, technological development and demonstration under Grant Agreement No. 603629) and MARS (European Union’s Seventh Framework Programme for research, technological development and demonstration under Grant Agreement No. 603378). Funding text #2 The authors declare that they have no competing interests. CIS Common Implementation Strategy DG Directorate General DPSIR Drivers–Pressure–State–Impacts–Response ECHA European Chemical Agency EEA European Environmental Agency EFSA European Food Safety Authority EU European Union ICPDR International Commission for the Protection of the Danube River ICPR International Commission for the Protection of the Rhine NGO Non-Governmental Organisation SDG sustainable development goals UN United Nations WFD Water Framework Directive

Species’ biological traits and ecological preferences are important components to better understand distribution patterns, to help assessing and evaluating the status of freshwater ecosystems and to support biodiversity conservation. In Europe, the Water Framework Directive has been the main driver for the development of ecological assessment systems in recent years, which often use biological traits and ecological preferences of species as source for bioindication. Comprehensive databases compiling such species traits have a longer tradition in the terrestrial realm, but for freshwater organisms, such a database was missing until the establishment of freshwaterecology.info (Schmidt-Kloiber and Hering 2015). The freshwaterecology.info online tool integrates various data sources into a comprehensive database of large-scale distribution patterns, biological traits and ecological preferences of freshwater species, including phytoplankton, diatoms, macrophytes, macro-invertebrates and fishes. The database hosts more than 21,000 European freshwater species/species-groups and information about their specific ecology, and it has more than 1,700 registered users. Based on the availability of funding, the database is constantly being expanded and amended, through experts' contributions, evaluation of recent publications or data analyses. Here we present the database development, its main components as well as some usage examples.

Freshwaters are among the most complex, dynamic, and diverse ecosystems globally. Despite their small share of the earth’s surface (less than 1%) they are home to over 10% of all known animal species. Biodiversity decrease in general and freshwater biodiversity decline in particular have recently received increasing attention, and various policy instruments are now targeting the conservation, protection and enhancement of biodiversity and associated ecosystem services. Surveillance programs as well as a variety of research projects have been producing a tremendous amount of freshwater-related information. Though there have been various attempts to build infrastructures for online collection of such data, tools and reports, they often provide only limited access to resources that can readily be extracted for conducting large scale analyses. Here, we present the Freshwater Information Platform, an open system of relevant freshwater biodiversity-related information. We provide a comprehensive overview of the platform’s core components, highlight their values, present options for their use, and discuss future developments. This is complemented by information on the platform’s current management structure, options for contributing data and research results and an outlook for the future.

Data on salinity tolerance of aquatic plant species are scarce, but required to better understand species’ responses in multiple stressed environments. We analyzed data from a Dutch Water board in the province of Zeeland according to the occurrence of plant taxa in relation to salinity (chloride concentration). The dataset contained 862 samples of plants (altogether 46 taxa) and chloride concentrations. The smallest range was found for Nuphar lutea occurring in sites with 43 to 140 mg l−1 Cl−. The widest range was observed for Glaux maritima occurring in sites with 710 to 22,000 mg l−1 Cl−. Two species (N. lutea and Potamogeton trichoides) had an optimum lower than 100 mg l−1 Cl−, while three taxa (G. maritima, Salicornia spp. and Ulva spp. (=non-filamentous)) had an optimum higher than 10,000 mg l−1 Cl−. Change points (CPs) were determined on salinity class level along the gradient. These CPs are defined as the class, at which the largest change in occurrence is determined. The CP of taxa that are relatively sensitive, such as Sparganium erectum and Carex riparia, were below 200 mg l−1 Cl−, while relative tolerant taxa, such as Stuckenia pectinata and Ranunculus sceleratus, had CPs at concentrations that were more than tenfold higher. The upper limit of the salinity range at which taxa occurred in the study area were generally similar to the few limits that were previously published. Implications for assigning species to water body types for implementing the Water Framework Directive in the Netherlands are discussed.

Recently, the Guardian published an article entitled “EU clean water laws under attack from industry lobbyists” by Arthur Neslen (https://www.theguardian.com/environment/2019/may/15/eu-clean-water-laws-under-attack-from-industry-lobbyists) expressing concerns regarding a roll back in European clean water regulations. As principal investigators of the large EU-funded project “SOLUTIONS for present and future emerging pollutants in land and water resources management”, we appreciate such an open debate on water quality protection in Europe, which we would like to enrich with conclusions from 5 years of extensive research and stakeholder dialogue within SOLUTIONS and other large EU projects., This article has been prepared as an outcome of the SOLUTIONS project (European Union’s Seventh Framework Programme for research, technological development and demonstration under Grant Agreement No. 603437).

Species distribution data are crucial for understanding biodiversity dynamics and the underlying drivers. For freshwaters, which cover only a small proportion of the world's surface, but host a large variety of species, knowledge on species occurrences is extremely important as they are among the most endangered ecosystems globally. However, a huge body of data gathered by scientists and water managers is currently difficult to access: systematic data publishing practices have not been fully adopted yet and data embedded in scientific papers and research project websites are often challenging to extract. At the same time, data and knowledge generated through publically-funded research or monitoring programmes are considered a common good. The Freshwater Information Platform (FIP) aims at pooling freshwater related research information from multiple projects and initiatives to make it easily accessible for scientists, water managers, conservationists and the interested public. The FIP consists of several major components, three of which form its “data publication unit”: The Freshwater Metadatabase (1) is an online tool where data characterising and documenting actual datasets can be entered in a simple way. With one more mouseclick these metadata can then be published as open access articles in the connected Freshwater Metadata Journal. The second part of the unit is the Freshwater Biodiversity Data Portal (2), where we aim to mobilise and publish the connected freshwater biodiversity data (occurrence records) through GBIF (Global Biodiversity Information Facility). The use of collected datasets for large-scale analyses and models is demonstrated in the Global Freshwater Biodiversity Atlas (3) that publishes interactive online maps featuring research results on freshwater biodiversity, threats and conservation priorities. Here, we focus on introducing these components as tools to streamline open access freshwater data publication, arguing it will improve the capacity to protect and manage freshwater biodiversity in the face of global change. We further present linkages to and cooperations with other key initiatives in the field, namely the "Alliance for Freshwater Life" as well as "FreshwaterBON".

This is an accepted author's manuscript. Embargo until March 4 2022. Hydromorphological river restoration can significantly alter habitat configuration and modify invertebrate assemblages of rivers and floodplains. However, the consequences of these changes for ecosystem functioning and aquatic-terrestrial interactions are not known. As a restored shoreline has a more heterogeneous structure compared to a straightened river, restoration is likely to impact aquatic-terrestrial linkages in multiple ways, which might be captured based on biomarker indicators to characterize changes in food web functioning. We conducted a large scale comparative study targeting eleven river restoration projects in central and northern Europe to assess effects of river restoration on trophic patterns across the aquatic-terrestrial interface. We investigated the isotopic composition (δ13C, δ15N) of prey and of invertebrate consumers stratifying between the aquatic, riparian and terrestrial zones. The isotopic distance of riparian arthropods to instream macroinvertebrates and terrestrial arthropods was used as a measure of trophic linkage, and its variation with riparian habitat composition was quantified. Restoration enhanced aquatic-terrestrial linkages, indicated especially by differentiation in the δ15N isotopic signatures between aquatic, riparian and terrestrial consumers, rather than by δ13C signatures. The δ15N isotopic signatures of riparian arthropods revealed a higher relative trophic position in restored sections (δ15NRestored: 8.64‰, n = 11) as compared to non-restored sections (δ15NDegraded: 8.05‰, n = 11), lending support to the conjecture that restoration increased the proportion of more highly enriched aquatic prey (δ15NRestored: 10.01‰; δ15NDegraded: 10.38‰) while simultaneously reducing the share of lower enriched terrestrial prey (δ15NRestored: 4.88‰; δ15NDegraded: 5.53‰). Riparian habitat diversity and the share of exposed sand and gravel bars were positively related to the strength of aquatic-terrestrial linkages (R2 = 0.28 and R2 = 0.31, respectively), pointing to the importance of habitat diversification in the riparian zone in promoting trophic linkages between river and floodplain. These findings expand our understanding of the multifaceted outcomes of hydromorphological restoration, beyond biodiversity in the aquatic environment. It highlights the need to expand our current set of indicators in order to mechanistic understand restoration effects on ecological networks spanning across boundaries. This knowledge is highly relevant for the large restoration efforts driven by legislative frameworks such as the Water Framework Directive in Europe.

Both ecosystem structure and functioning determine ecosystem status and are important for the provision of goods and services to society. However, there is a paucity of research that couples functional measures with assessments of ecosystem structure. In mid-sized and large rivers, effects of restoration on key ecosystem processes, such as ecosystem metabolism, have rarely been addressed and remain poorly understood. We compared three reaches of the third-order, gravel-bed river Ruhr in Germany: two reaches restored with moderate (R1) and substantial effort (R2) and one upstream degraded reach (D). Hydromorphology, habitat composition, and hydrodynamics were assessed. We estimated gross primary production (GPP) and ecosystem respiration (ER) using the one-station open-channel diel dissolved oxygen change method over a 50-day period at the end of each reach. Moreover, we estimated metabolic rates of the combined restored reaches (R1 + R2) using the two-station open-channel method. Values for hydromorphological variables increased with restoration intensity (D

The Water Framework Directive (WFD) is a pioneering piece of legislation that aims to protect and enhance aquatic ecosystems and promote sustainable water use across Europe. There is growing concern that the objective of good status, or higher, in all EU waters by 2027 is a long way from being achieved in many countries. Through questionnaire analysis of almost 100 experts, we provide recommendations to enhance WFD monitoring and assessment systems, improve programmes of measures and further integrate with other sectoral policies. Our analysis highlights that there is great potential to enhance assessment schemes through strategic design of monitoring networks and innovation, such as earth observation. New diagnostic tools that use existing WFD monitoring data, but incorporate novel statistical and trait-based approaches could be used more widely to diagnose the cause of deterioration under conditions of multiple pressures and deliver a hierarchy of solutions for more evidence-driven decisions in river basin management. There is also a growing recognition that measures undertaken in river basin management should deliver multiple benefits across sectors, such as reduced flood risk, and there needs to be robust demonstration studies that evaluate these. Continued efforts in ‘mainstreaming’ water policy into other policy sectors is clearly needed to deliver wider success with WFD goals, particularly with agricultural policy. Other key policy areas where a need for stronger integration with water policy was recognised included urban planning (waste water treatment), flooding, climate and energy (hydropower). Having a deadline for attaining the policy objective of good status is important, but even more essential is to have a permanent framework for river basin management that addresses the delays in implementation of measures. This requires a long-term perspective, far beyond the current deadline of 2027 This work was supported by the MARS project (Managing Aquatic ecosystems and water Resources under multiple Stress) funded under the EU 7th Framework Programme, Theme 6 (Environment including Climate Change), Contract No.: 603378 (http://www.mars-project.eu). Author contributions were also based on work from other EUfunded projects including: Sindre Langaas co-funded from the FAIRWAYProject (producing good water quality for drinking water supplies), funded by European Commission, Directorate General for Research under Framework Programme HORIZON 2020, Contract No.: 727984; Sergi Sabater GlobAqua (FP7-ENV-2013-603629); Josselin Rouillard AQUACROSS (H2020 Grant Agreement no. 642317). Angel Borja also provided inputs and results from a Summer School, organized by AZTI, with the support of the EEAcademy (European Environment Agency) and the Basque Water Agency (URA). Kirsty Blackstock and Laurence Carvalho were also supported from Scottish Government's Strategic Research Programme (2016–2021) WP1.2 on Waters. Bryan Spears was supported by the Our Phosphorus Future Project, supported by NERC grant no. NE/ P008798/1, the United Nations – Environment, and the European Sustainable Phosphorus Platform

The distribution of a species along a thermal gradient is commonly approximated by a unimodal response curve, with a characteristic single optimum near the temperature where a species is most likely to be found, and a decreasing probability of occurrence away from the optimum. We aimed at identifying thermal response curves (TRCs) of European freshwater species and evaluating the potential impact of climate warming across species, taxonomic groups, and latitude. We first applied generalized additive models using catchment-scale global data on distribution ranges of 577 freshwater species native to Europe and four different temperature variables (the current annual mean air/water temperature and the maximum air/water temperature of the warmest month) to describe species TRCs. We then classified TRCs into one of eight curve types and identified spatial patterns in thermal responses. Finally, we integrated empirical TRCs and the projected geographic distribution of climate warming to evaluate the effect of rising temperatures on species’ distributions. For the different temperature variables, 390–463 of 577 species (67.6%–80.2%) were characterized by a unimodal TRC. The number of species with a unimodal TRC decreased from central toward northern and southern Europe. Warming tolerance (WT = maximum temperature of occurrence—preferred temperature) was higher at higher latitudes. Preferred temperature of many species is already exceeded. Rising temperatures will affect most Mediterranean species. We demonstrated that freshwater species’ occurrence probabilities are most frequently unimodal. The impact of the global climate warming on species distributions is species and latitude dependent. Among the studied taxonomic groups, rising temperatures will be most detrimental to fish. Our findings support the efforts of catchment-based freshwater management and conservation in the face of global warming. CA extern

Increased fine sediment deposition is recognised as one of the major causes of biological impairment of rivers and streams influencing all components of aquatic communities. Notably, stream macroinvertebrates are affected showing changes in abundance and community composition. This makes macroinvertebrates an attractive choice for biomonitoring fine sediment stress. However, there are substantial knowledge gaps regarding the quantification of deposited fine sediment and the identification of taxa sensitive to fine sediment deposition, which could serve as indicators. In this study, we developed a stream type-specific index based on the taxon-specific response of macroinvertebrates to deposited fine sediment in small, coarse substrate-dominated mountain streams. We sampled fine sediment at 73 sampling sites in Western Germany (Europe) in spring 2014 and 2015 using a sediment remobilization technique. Macroinvertebrate taxalists originating from WFD monitoring surveys were available for all sites. We applied Threshold Indicator Taxa ANalysis (TITAN) on the fine sediment mass of the sampling sites and the corresponding macroinvertebrate taxalists to identify indicator taxa, which were then used for index development. In total, TITAN identified 95 reliable indicator taxa, of which some taxa tolerated large amounts of fine sediment (e.g., Gammarus roeselii and Tubificidae Gen. sp.), while others were found to be highly sensitive to increased fine sediment mass (e.g., Elodes sp. and Limnius perrisi). The newly developed index was tested on an independent data set and performed well in detecting fine sediment stress (Spearman's r = 0.63). Furthermore, the index was better related to the deposited fine sediment mass as compared to other fine sediment indices and standard metrics used for monitoring purposes under the Water Framework Directive (WFD). The diagnostic index can be a cost-effective biomonitoring tool for stream managers and can be used as a proxy for the impact of deposited fine sediment on the reach scale.

Background: The endocannabinoid system plays a pathophysiological role in metabolic and cardiovascular disorders. G protein-coupled receptor (GPR) 55 is a novel cannabinoid receptor expressed by various lymphocyte subsets, in particular γδT cells, innate lymphoid cells and B1 cells. Its role in regulating immune functions and atherosclerosis is unknown. Methods: We studied early and advanced atherosclerotic plaques and inflammatory parameters in apolipoprotein E deficient (ApoE-/-) and ApoE-/-GPR55-/- mice after 4 or 16 weeks Western Diet (WD), respectively (n=12-15 per group). GPR55 mRNA expression was assessed in human carotid artery plaques (n=29) and healthy control vessels (left internal thoracic arteries; n=28). Results: ApoE-/-GPR55-/- mice had significantly 1.9 to 2.3-fold increased plaque sizes after 4 and 16 weeks WD compared to ApoE-/- controls with higher macrophage content at early stage, but less macrophage and more collagen content at advanced stage. This was accompanied by enhanced aortic pro-inflammatory cytokine mRNA expression (IL-6, TNFα, IL-1β, iNOS) as well as massively upregulated IgG1 plasma levels. Moreover, GPR55 deficiency was associated with increased circulating, splenic and aortic lymphocyte counts after 4 and 16 weeks WD. The most striking (2 to 4-fold) increase was found in γδT cells, with less pronounced increases in the total CD3+ T cell population and CD4+ and CD8+ subsets. This was paralleled by systemic increases in blood monocyte and neutrophil counts, likely due to enhanced myelopoiesis as suggested by enhanced bone marrow myeloid cell counts. At advanced atherosclerosis, ApoE-/-GPR55-/- had significantly higher NK cell numbers in blood and lymphoid organs, suggesting a possible regulation of cytotoxic lymphocyte responses. In view of a potential relevance for human pathophysiology, GPR55 mRNA levels were significantly higher in human plaque samples compared to non-atherosclerotic control vessels. Conclusion: GPR55 deficiency promotes atherosclerosis associated with a more pro-inflammatory phenotype. We may speculate that GPR55 negatively regulates the proatherogenic activity of lymphocyte subsets such as γδT cells, which deserves further investigation.

Aims Myocardial infarction (MI) leads to an enhanced release of endocannabinoids and a massive accumulation of neutrophils and monocytes within the ischaemic myocardium. These myeloid cells originate from haematopoietic precursors in the bone marrow and are rapidly mobilized in response to MI. We aimed to determine whether endocannabinoid signalling is involved in myeloid cell mobilization and cardiac recruitment after ischaemia onset. Methods and results Intravenous administration of endocannabinoid 2-arachidonoylglycerol (2-AG) into wild type (WT) C57BL6 mice induced a rapid increase of blood neutrophil and monocyte counts as measured by flow cytometry. This effect was blunted when using cannabinoid receptor 2 knockout mice. In response to MI induced in WT mice, the lipidomic analysis revealed significantly elevated plasma and cardiac levels of the endocannabinoid 2-AG 24 h after infarction, but no changes in anandamide, palmitoylethanolamide, and oleoylethanolamide. This was a consequence of an increased expression of 2-AG synthesizing enzyme diacylglycerol lipase and a decrease of metabolizing enzyme monoacylglycerol lipase (MAGL) in infarcted hearts, as determined by quantitative RT-PCR analysis. The opposite mRNA expression pattern was observed in bone marrow. Pharmacological blockade of MAGL with JZL184 and thus increased systemic 2-AG levels in WT mice subjected to MI resulted in elevated cardiac CXCL1, CXCL2, and MMP9 protein levels as well as higher cardiac neutrophil and monocyte counts 24 h after infarction compared with vehicle-treated mice. Increased post-MI inflammation in these mice led to an increased infarct size, an impaired ventricular scar formation assessed by histology and a worsened cardiac function in echocardiography evaluations up to 21 days. Likewise, JZL184-administration in a myocardial ischaemia-reperfusion model increased cardiac myeloid cell recruitment and resulted in a larger fibrotic scar size. Conclusion These findings suggest that changes in endocannabinoid gradients due to altered tissue levels contribute to myeloid cell recruitment from the bone marrow to the infarcted heart, with crucial consequences on cardiac healing and function., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

Aquatic biomonitoring has become an essential task in Europe and many other regions as a consequence of strong anthropogenic pressures affecting the health of lakes, rivers, oceans and groundwater. A typical assessment of the environmental quality status, such as it is required by European but also North American and other legislation, relies on matching the composition of assemblages of organisms identified using morphological criteria present in aquatic ecosystems to those expected in the absence of anthropogenic pressures. Through decade-long and difficult intercalibration exercises among networks of regulators and scientists in European countries, a pragmatic biomonitoring approach was developed and adopted, which now produces invaluable information. Nonetheless, this approach is based on several hundred different protocols, making it susceptible to issues with comparability, scale and resolution. Furthermore, data acquisition is often slow due to a lack of taxonomic experts for many taxa and regions and time-consuming morphological identification of organisms. High-throughput genetic screening methods such as (e)DNA metabarcoding have been proposed as a possible solution to these shortcomings. Such "next-generation biomonitoring", also termed "biomonitoring 2.0", has many advantages over the traditional approach in terms of speed, comparability and costs. It also creates the potential to include new bioindicators and thereby further improves the assessment of aquatic ecosystem health. However, several major conceptual and technological challenges still hinder its implementation into legal and regulatory frameworks. Academic scientists sometimes tend to overlook legal or socioeconomic constraints, which regulators have to consider on a regular basis. Moreover, quantification of species abundance or biomass remains a significant bottleneck to releasing the full potential of these approaches. Here, we highlight the main challenges for next-generation aquatic biomonitoring and outline principles and good practic, COST - European Cooperation in Science and Technology(CA15219). COST Action DNAqua-Net (CA15219), supported by the COST (European Cooperation in Science and Technology) programme