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Intermittent stream research focuses mostly on pristine streams. The impacts of nutrient enrichment on invertebrate communities in these systems thus remains underexplored, especially in temperate climates. This study aimed to compare taxa survival during stream drying within pristine and nutrient-enriched sediment streambeds and to evaluate seedbank contribution for community recovery. Ten dry sediment subsamples were each collected from three streams of each nutrient status type. These were rehydrated for 60 days in laboratory with persisting and hatching invertebrates being recorded. Oligochaetes and molluscs were the most abundant; stoneflies and mayflies were common; caddisflies were represented by only a few specimens. The seedbank comprised of around one-third of taxa recorded during flow phases with slightly higher taxa numbers in nutrient-enriched streams. Moisture content positively affected seedbank taxa richness, while dry period duration decreased it. Taxa richness has a unimodal response to nutrient enrichment, with fine sediment proportion revealing no significant effect. Our results show a richer macroinvertebrate seedbank in drying sediments under moist conditions with mild nutrient enrichment, while raised nutrient levels limited macroinvertebrate survival. These results highlight the crucial role of seedbanks in community recovery of intermittent temperate streams, which will become more common with climate change.

Microbial communities are known to be sensitive indicators for water pollution and biomonitoring assessment. In this study, we aimed at observation of microbial abundance and community composition in the mountain river Morávka. The results showed temporal and spatial changes in total cell abundance (TCA). TCA reached 105–106 cells/ml, increasing values were detected towards the mouth with maxima in summer and autumn months. Out of Eubacteria Betaproteobacteria and Cytophaga-Flavobacterium were found to predominate, while Archaea represented only 4.8 % of TCA. Along the flow three distinct patterns of phylogenetic groups' share were revealed related to increasing pollution. Microbial community composition was found to be most significantly dependent on the elevation and the sampling date. Moreover, environmental variables like O2 saturation, water temperature, trophic potential and pH influenced microbial community as well. Statistical analyses showed significant seasonal (23.5 %) and spatial (4.7 %) changes in microbial community composition.

Humans have severely altered freshwater ecosystems globally, causing a loss of biodiversity. Regulatory frameworks, like the Water Framework Directive, have been developed to support actions that halt and reverse this loss. These frameworks use typology systems that summarize freshwater ecosystems into environmentally delineated types. Within types, ecosystems that are minimally impacted by human activities, i.e., in reference conditions, are expected to be similar concerning physical, chemical, and biological characteristics. This assumption is critical when water quality assessments rely on comparisons to type-specific reference conditions. Lyche Solheimet al. (2019) developed a pan-European river typology system, the Broad River Types, that unifies the nationalWater Framework Directive typology systems and is gaining traction within the research community. However, it is unknown how similar biological communities are within these individual Broad River Types. We used analysis of similarities and classification strength analysis to examine if the Broad River Types delineate distinct macroinvertebrate communities across Europe and whether they outperform two ecoregional approaches: the European Biogeographical Regions and Illies' Freshwater Ecoregions. We etermined indicator and typical taxa for the types of all three typology systems and evaluated their distinctiveness. All three typology systems captured more variation in macroinvertebrate communities than random combinations of sites. The results were similar among typology systems, but the Broad River Types always performed worse than either the Biogeographic Regions or Illies' Freshwater Ecoregions. Despite reaching statistical significance, the statistics of analysis of similarity and classification strength were low in all tests indicating substantial overlap among the macroinvertebrate communities of different types. We conclude that the Broad River Types do not represent an improvement upon existing freshwater typologies when used to delineate macroinvertebrate communities and we propose future avenues for advancement: regionally constrained types, better recognition of intermittent rivers, and consideration of biotic communities. This study was part of the GETREAL (Incorporating spatial and seasonal variability in community sensitivity into chemical risk assessment) project, which was funded by the European Chemical Industry Council long-range research initiative (CEFIC-LRi project ECO 50). Dénes Schmera was supported by the NKFIH K140352 and 471-3/2021 grants. Petr Pařil, Marek Polášek and Michal Straka were supported by the P505-20-17305S grant. We are grateful to the staff that collected and analyzed data for the AQEM (EU FP5, contract No: EVK1-CT1999- 00027), BIODROUGHT, STAR (EU FP5, contract No: EVK1-CT 2001-00089), and WISER (EU FP7, contract No 226273) projects and to the various water agencies that participated in the abiotic and biotic data collection and analysis.

With ongoing climate change and increasing water resource pressures, the knowledge and predictability of stream drying is essential for water management. However, the hydrological data for assessing the flow regime of temporary streams are often non-existent or scarce. The flow regime strongly affects stream ecological functioning and ecosystem processes. A few biological indices have been developed in the past decade to assess community responses to flow intermittency. One of them - the Biodrought Index, used to recognise antecedent stream drying based on benthic invertebrate assemblage composition - was initially intended for deployment in the Czech Republic. Here we report on a test of how reliably this index can be used in Central Europe. We used five independent data sets of macroinvertebrate samples collected during the flowing phase in five countries: Austria, Czech Republic, Germany, Hungary and Slovakia. Altogether 89, 26 and 220 samples were assessed from intermittent, near-perennial and perennial sites, respectively. Each sample was assigned to one of three flow intermittence categories according to the Biodrought Index and then compared with the flow regime recognised by hydrological observations and gauging station data. In most cases, the Biodrought Index clearly reflected the previous flow state and identified streamflow cessation. The misidentification rate between intermittent and perennial samples was very low, ranging from 0% to 6%. Classification rate of correctly recognised samples ranged from 54% to 93% and misclassification rate between near-perennial and perennial/intermittent category was 6% to 46%. Overall, this study confirmed the robustness and the reliability of the Biodrought Index, which proved to be an effective tool in assessing the recent hydrological history of small and medium-sized streams. The index can improve the interpretation of the macroinvertebrate assemblage data collected for ecological status assessment, can help to evaluate the effectiveness of river restoration projects or identify water resource pressures. Hence, we consider the Biodrought Index a useful method for indicating antecedent stream drying in the extensive area of Central Europe and thus helpful in monitoring and managing river ecosystems.

Groundwater dependent ecosystems are recognized as biodiversity hotspots, being,apart many negative human impacts, highly threatened also by ongoing climate warming. Clitellata (Annelida) are dominant invertebrates of permanent fauna in spring habitats, representing a heterogeneous group including both specialized cold stenothermic and ubiquitous eurythermic species. Therefore, they seem to be a good model group to compare the effects of local spring water temperature (recorded in situ by data loggers) and mesoclimate (i.e., local) air temperature. By the analysis of clitellate assemblages at 41 isolated Western Carpathian spring fens, we found that their species composition was significantly driven by mesoclimate air temperature and springwater temperature independently of other important environmentalvariables (i.e., water mineralization, oxygen content, and total organic carbon). Theeffect of various environment related and temperature related variables on thenumber of clitellate species was analyzed separately for two categories, that is,substrate dwellers (endobenthic species) and surface active (epibenthic) species. The decrease of the number of species with the increasing amount of inorganic particles in substrate was observed in the substrate dwellers. Mesoclimate air temperature had no significant effect on the number of species of substrate dwellers.However, water temperature, specifically its daily fluctuation, turned out to have a strong effect. Only the sites with no or moderate fluctuation were inhabited by cold stenotherm spring specialists and cold water species. In contrast, no significant response to any temperature parameter was found for the number of surface active species, which was driven only by other environmental variables. Our results suggest that climatically induced increase in temperature fluctuation of spring waters can result in notable reduction of cold adapted clitellate species (mainly the family Lumbriculidae) at the expense of eurythermic species. Such a scenario predicts compositional changes leading to clitellate assemblages with a dominance ofgeneralist and semiaquatic species.

Little is known about macroinvertebrate assemblages inhabiting aquatic-terrestrial transition zones, particularly at groundwater-fed wetlands. We studied diversity and vertical distribution of Dipteran assemblages in 27 spring fens characterised by variable groundwater chemistry ranging from acidic to extremely calcium rich. We sampled semiaquatic habitats of aquatic-terrestrial zones and compared their dipteran assemblages with those of truly aquatic habitats in spring patches. Our study showed that semiaquatic habitats create an important part of spring fens, harbouring about one half of dipteran taxa inhabiting spring fens, with a similar proportion of spring specialists as in aquatic habitats. Dipteran abundance decreased gradually with sediment depth, being the highest in the uppermost layer. However, vertical distribution of Diptera differed among fens of different mineral richness, with the average depth of dipteran counts decreasing from calcareous to mineral-poor Sphagnum fens. Calcium carbonate incrustations in calcareous fens might block migration to deeper horizons and therefore may cause high sensitivity of dipteran assemblages to water level fluctuations induced by various factors, such as climate changes and water abstraction. Semiaquatic habitats contribute significantly to the species richness of dipteran assemblages by providing additional microhabitats in the peripheral parts of spring fens, which are rare habitats of high conservation value.

International audience; Aquatic invertebrate communities inhabiting intermittent rivers that are characterised by recurrent drying events (flow cessation or complete disappearance of surface water) often show rapid recovery upon flow resumption. Such rapid recovery is possible thanks to specific resistance and resilience traits that species adapted to river drying often exhibit. However, differences in community response to drying can be expected between historically drying (HD) networks-those IRs with a long history of flow intermittence-and recently drying (RD) networks, where drying is a novel, often human-induced, phenomenon. The invertebrate species found in RD networks may lack the adaptations that are known to facilitate quick community recovery upon rewetting and could thus be dramatically affected by drying. Unfortunately, the responses of aquatic communities in RD networks are still poorly explored, limiting our capacity to predict and mitigate future biodiversity changes.Here, we compared the responses of aquatic invertebrate communities to drying in nine pairs of intermittent and perennial river reaches from HD networks across France and nine pairs from RD networks across the Czech Republic. Using both taxonomic and functional perspectives, differences in alpha- and beta-diversity patterns between perennial and intermittent sites were evaluated separately for HD and RD groups, and before and after drying over several years.Drying had stronger effects on taxonomic richness in RD compared to HD networks. In addition, drying greatly altered spatial and temporal beta-diversity in RD networks, but it marginally affected beta-diversity in HD networks. Communities of HD networks showed a higher proportion of resistant taxa than RD networks.These results suggest that recent drying can have, at least on a short time scale (i.e. years), stronger effects on aquatic communities in RD networks compared to those in HD networks.Because drying duration, frequency, and spatial extent are increasing with climate change, RD networks could soon reach tipping points, calling for long-term monitoring of biodiversity in these novel ecosystems.

1. Rivers are dynamic ecosystems in which both human impacts and climate-driven drying events are increasingly common. These anthropogenic and natural stressors interact to influence the biodiversity and functioning of river ecosystems. Disentangling ecological responses to these interacting stressors is necessary to guide management actions that support ecosystems adapting to global change. 2. We analysed the independent and interactive effects of human impacts and natural drying on aquatic invertebrate communities—a key biotic group used to assess the health of European freshwaters. We calculated biological response metrics representing communities from 406 rivers in eight European countries: taxonomic richness, functional richness and redundancy, and biomonitoring indices that indicate ecological status. We analysed metrics based on the whole community and on a group of taxa with traits promoting resistance and/or resilience (‘high RR’) to drying. We also examined how responses vary across Europe in relation to climatic aridity. 3. Most community metrics decreased independently in response to impacts and drying. A richness-independent biomonitoring index (the average score per taxon; ASPT) showed particular potential for use in biomonitoring, and should be considered alongside new metrics representing high RR diversity, to promote accurate assessment of ecological status. 4. High RR taxonomic richness responded only to impacts, not drying. However, these predictors explained little variance in richness and other high RR metrics, potentially due to low taxonomic richness. Metric responsiveness could thus be enhanced by developing region-specific high RR groups comprising sufficient taxa with sufficiently variable impact sensitivities to indicate ecological status. 5. Synthesis and applications. Metrics are needed to assess the ecological status of dynamic river ecosystems—including those that sometimes dry—and thus to identify priority sites requiring action to tackle the causes of environmental degradation. Our results inform recommendations guiding the development of such metrics. We propose concurrent use of richness-independent ‘average score per taxon’ indices and metrics that characterize the richness of resistant and resilient taxa. We observed interactions between aridity, impacts and drying, highlighting that these new metrics should be region specific, river type specific and adaptable, promoting their ability to inform management actions that protect biodiversity in river ecosystems responding to climate change. European Cooperation in Science and Technology. Grant Number: CA15113

The study was supported by the COST Action CA15113 Science and Management of Intermittent Rivers and Ephemeral Streams (http://www.smires.eu), funded by COST (European Cooperation in Science and Technology). NC was supported by the French research program Make Our Planet Great Again. MC-A was supported by the MECODISPER project (CTM2017-89295-P) funded by the Spanish Ministerio de Economia, Industria y Competitividad (MINECO) - Agencia Estatal de Investigacion (AEI) and cofunded by the European Regional Development Fund (ERDF). AC-R acknowledges funding by MINECO-AEI-ERDF (CGL2014-53140-P). CG-C was supported by the EDRF (COMPETE2020 and PT2020) and the Portuguese Foundation for Science and Technology, through the CBMA strategic program UID/BIA/04050/2019 (POCI-01-0145-FEDER-007569) and the STREAMECO project (Biodiversity and ecosystem functioning under climate change: from the gene to the stream, PTDC/CTA-AMB/31245/2017). JH was supported by the project 'Global taxonomic, functional and phylogenetic diversity of stream macroinvertebrate communities: unravelling spatial trends, ecological determinants and anthropogenic threats' funded by the Academy of Finland. PP and MP were supported by the Czech Science Foundation (P505-20-17305S). ZC was supported by the projects EFOP-3.6.1.-16-2016-00004, 20765-3/2018/FEKUTSTRAT and TUDFO/47138/2019-ITM. We thank two anonymous reviewers for insightful feedback that improved an earlier draft of this manuscript., Dispersal is an essential process in population and community dynamics, but is difficult to measure in the field. In freshwater ecosystems, information on biological traits related to organisms’ morphology, life history and behaviour provides useful dispersal proxies, but information remains scattered or unpublished for many taxa. We compiled information on multiple dispersal-related biological traits of European aquatic macroinvertebrates in a unique resource, the DISPERSE database. DISPERSE includes nine dispersal-related traits subdivided into 39 trait categories for 480 taxa, including Annelida, Mollusca, Platyhelminthes, and Arthropoda such as Crustacea and Insecta, generally at the genus level. Information within DISPERSE can be used to address fundamental research questions in metapopulation ecology, metacommunity ecology, macroecology and evolutionary ecology. Information on dispersal proxies can be applied to improve predictions of ecological responses to global change, and to inform improvements to biomonitoring, conservation and management strategies. The diverse sources used in DISPERSE complement existing trait databases by providing new information on dispersal traits, most of which would not otherwise be accessible to the scientific community., COST Action Science and Management of Intermittent Rivers and Ephemeral Streams - COST (European Cooperation in Science and Technology) CA15113, French research program Make Our Planet Great Again, MECODISPER project - Spanish Ministerio de Economia, Industria y Competitividad (MINECO) - Agencia Estatal de Investigacion (AEI) CTM2017-89295-P, European Union (EU), MINECO-AEI-ERDF CGL2014-53140-P, EDRF (COMPETE2020), Portuguese Foundation for Science and Technology, through the CBMA strategic program UID/BIA/04050/2019 (POCI-01-0145-FEDER-007569), STREAMECO project (Biodiversity and ecosystem functioning under climate change: from the gene to the stream) PTDC/CTA-AMB/31245/2017, project 'Global taxonomic, functional and phylogenetic diversity of stream macroinvertebrate communities: unravelling spatial trends, ecological determinants and anthropogenic threats' - Academy of Finland, Grant Agency of the Czech Republic P505-20-17305S, EDRF (PT2020), EFOP-3.6.1.-16-2016-00004, 20765-3/2018/FEKUTSTRAT, TUDFO/47138/2019-ITM

Motivation Dispersal is an essential process in population and community dynamics but is difficult to measure in the field. In freshwater systems, relevant information on the dispersal of many taxa remains scattered or unpublished, and biological traits related to organisms’ morphology, life history and behaviour offer useful dispersal proxies. We compiled information on selected dispersal-related biological traits of European aquatic macroinvertebrates in a unique source: the DISPERSE database. Information within DISPERSE can be used to address fundamental questions in metapopulation ecology, metacommunity ecology, macroecology, and eco-evolutionary research. From an applied perspective, the consideration of dispersal proxies can also improve predictions of ecological responses to global change, and contribute to more effective biomonitoring and conservation management strategies. Main types of variable contained Selected macroinvertebrate dispersal-related biological traits: maximum body size, adult female wing length, adult wing pair type, adult life span, number of reproductive cycles per year, lifelong fecundity, dispersal mode (i.e. active, passive, aquatic, aerial), and propensity to drift. Spatial location Europe. Time period Taxa considered are extant with recent records. Most data were collected in the 20th century and in the period 2000-2019. Major taxa and level of measurement Aquatic macroinvertebrates from riverine and lacustrine ecosystems, including Mollusca, Annelida, Platyhelminthes, and Arthropoda such as Crustacea and Insecta. For Insecta, aquatic stages and the aerial (i.e. flying) phases of adults were considered separately. Genus-level taxonomic resolution used, except for some Annelida and Diptera, which are coded at the sub-class, family or sub-family level. In total, the database includes 39 trait categories grouped into nine dispersal-related traits for 480 taxa. Software format The data file is in Excel workbook. BIOSKETCH Many of the authors are members of the European Cooperation in Science and Technology (COST) Action CA15113 Science and Management of Intermittent Rivers and Ephemeral Streams (SMIRES, www.smires.eu ), which aims to improve our understanding of intermittent rivers and ephemeral streams (IRES) and translate this into science-based, sustainable management of river networks. One of the main goals of SMIRES is to facilitate sharing of data and experience, bringing together researchers from many disciplines and stakeholders and creating synergies through networking. The dataset provided and analyzed herein reflects networking and collaboration within the SMIRES working group dedicated to Community Ecology and Biomonitoring.

Climate warming and associated environmental changes lead to compositional shifts and local extinctions in various ecosystems. Species closely associated with rare island-like habitats such as groundwater-dependent spring fens can be severely threatened by these changes due to a limited possibility to disperse. It is, however, largely unknown to what extent mesoclimate affects species composition in spring fens, where microclimate is buffered by groundwater supply. We assembled an original landscape-scale dataset on species composition of the most waterlogged parts of isolated temperate spring fens in the Western Carpathian Mountains along with continuously measured water temperature and hydrological, hydrochemical, and climatic conditions. We explored a set of hypotheses about the effects of mesoclimate air and local spring-water temperature on compositional variation of aquatic (macroinvertebrates), semi-terrestrial (plants) and terrestrial (land snails) components of spring-fen biota, categorized as habitat specialists and other species (i.e. matrix-derived). Water temperature did not show a high level of correlation with mesoclimate. For all components, fractions of compositional variation constrained to temperature were statistically significant and higher for habitat specialists than for other species. The importance of air temperature at the expense of water temperature and its fluctuation clearly increased with terrestriality, i.e. from aquatic macroinvertebrates via vegetation (bryophytes and vascular plants) to land snails, with January air temperature being the most important factor for land snails and plant specialists. Some calcareous-fen specialists with a clear distribution centre in temperate Europe showed a strong affinity to climatically cold sites in our study area and may hence be considered as threatened by climate warming. We conclude that prediction models solely based on air temperature may provide biased estimates of future changes in spring fen communities, because their aquatic and semiterrestrial components are largely affected by water temperature that is modified by local hydrological and landscape settings.

An initial checklist of mayflies (Ephemeroptera) of Iran is compiled based on critical review of available literature data, complemented with new data from 38 localities of Gilan and Ardabil provinces. At present, altogether only 46 species and 25 genera are known from Iran, 18 species are reported as new to Iran in this study. Some previously published data are critically evaluated and doubtful taxa are excluded from the list. Basic analysis of the distribution and biogeography of recorded species is given. Procloeon (Pseudocentroptilum) caspicum Sroka,sp. n.is described based on mature larva and egg. Critical differential diagnostic characters distinguishing the species from related taxa are discussed in detail.

Many streams in the extensive Central European region have an intermittent flow regime. Conventional hydrological methods used to identify zero-flow conditions, and in particular drying events, have limited use when assessing large areas dominated by low-order streams. We developed a novel multimetric index to recognise antecedent stream drying based on the analysis of benthic macroinvertebrate communities. The data used to develop the index were collected in pristine streams with different flow permanence regimes between 2012 and 2014, using standard sampling methods for ecological status assessment. The data include 64 perennial, 19 near-perennial and 27 intermittent benthic macroinvertebrate samples. Metrics considered for the index included variables based on (i) the occurrence of indicator taxa, (ii) the proportion of biological and ecological traits, and (iii) structural community metrics. Linear discriminant analysis identified the metric combinations that best discriminated among the three flow permanence categories. Different metrics were used in the final multimetric index calculation for the autumn and spring season that followed stream drying. In both seasons, the index included the proportion of indicator taxa and the proportion of taxa with high body flexibility. In addition, the autumn index included the proportion of taxa with a preference for organic substrates, whereas in spring the index included total abundance. Independent data from regulatory monitoring activity were used to validate the accuracy of the index. The correct classification of independent samples was 92% and 96% for samples from perennial and non-perennial sites, respectively. The index can be calculated using data collected by routine monitoring programmes used to assess ecological status and provides information about stream intermittence where conventional hydrological monitoring is limited. As intermittent streams increase in extent in global regions including Central Europe, the tool may be of particular interest to those who use invertebrates to monitor or manage these ecosystems.

Temporary streams are becoming increasingly common, but ecological responses to streambed drying are poorly characterized in the temperate continental region of central Europe. In addition, global research has focused on community responses to drying, whereas effects on individual populations remain unknown. We explored the population structure of Gammarus fossarum (Crustacea: Amphipoda) in a central European temporary stream. Benthic gammarids were sampled on five dates during a flow recession, one date between two drying events (of 10 and 20 days, respectively), and five dates after flow resumed. Additional benthic samples were taken from isolated pools and dry sediments during drying events, and freeze cores were collected to compare the vertical distribution of amphipods during wet and dry phases. Gammarids were measured, adults distinguished from juveniles, adults sexed, and female reproductive state determined. Densities increased during flow recession, potentially reflecting both a decline in submerged habitat availability and seasonal increases in juvenile abundance. Persistence within dry benthic sediments was minimal, whereas pools and saturated subsurface sediments supported high population densities. Juveniles comprised 80 % of the subsurface population, suggesting that their ability to inhabit small interstices promotes persistence within the dry reach. Juveniles also comprised 92 % of pool inhabitants, despite their potential exposure to predation. Adults dominated after flow resumed, and population structure was altered post-drying by the loss of spring-recruited juveniles and reproductive females. Our results suggest that streambed drying may have longer-term effects than typically characterized by community-level studies. We recommend management actions that support populations of ecologically important species as they adapt to changing flow regimes.

International audience; Intermittent streams are naturally dominant landscape features of Mediterranean and arid regions, but also occur more and more in humid climates, such as in the Czech Republic. Organism abilities to cope with drying (i.e. resistance forms) have been quantified in naturally intermittent streams from Mediterranean and arid regions, in which long-term flow intermittence patterns have promoted physiological adaptations. In contrast, the capacity of aquatic communities to persist without requiring resistance adaptations under recent intermittent flow regimes in more humid climates is virtually unexplored, along with its contribution to community recovery upon rewetting. Here, we addressed the ability of aquatic invertebrates devoid of specific desiccation-resistance forms (e.g. cysts or eggs) to cope with climate change-induced flow intermittence from rivers in continental climate. Owing to the high relative air humidity, the importance of riparian cover and the short duration of drying events, we expected taxonomically and functionally rich communities to persist in the dry streambed during phases with no surface water and to contribute to community recovery upon flow resumption. To explore these ideas, we collected invertebrate communities in the riverbeds before, during and after drying from 10 intermittent rivers in the Czech Republic. We quantified the pool of organisms remaining alive in the dry riverbeds and determined its taxonomic and functional contribution to the recovery of benthic communities upon rewetting. Of the organisms collected, 83%, belonging to 22 taxa, were able to survive during the dry phase without producing desiccation-resistance forms. This pool of organisms contributed substantially both taxonomically and functionally to the quick recovery of benthic communities. The exponential decrease in taxonomic and functional richness implies an initial quick loss of sensitive taxa, while a pool of less sensitive taxa persisted long in the dry riverbeds, hence contributing to the fast community recovery upon rewetting. Survival rates of active aquatic macroinvertebrates devoid of specific desiccation-resistance adaptations have rarely been quantified. Probably promoted by benign environmental conditions prevailing on dry riverbeds in this study, their survival demonstrated the need to protect communities in dry riverbed and their adjacent riparian environments so that assemblages can recover rapidly from short periods without river flow. Riparian forest management along intermittent streams from continental climates could help conserve the value of dry streambeds as a source of resilience for riverine communities.

The dataset (Data File S1; DOI: 10.6084/m9.figshare.8863721) and the R code used to generate the results (Code S1; DOI: 10.6084/m9.figshare.8863655), including step by step explanations of the statistical tests, have been deposited in Figshare Digital Repository (https://figshare.com/projects/Sediment_Respiration_Pulses_in_Intermittent_Rivers_and_Ephemeral_Streams/66104)., Intermittent rivers and ephemeral streams (IRES) may represent over half the global stream network, but their contribution to respiration and carbon dioxide (CO2) emissions is largely undetermined. In particular, little is known about the variability and drivers of respiration in IRES sediments upon rewetting, which could result in large pulses of CO2. We present a global study examining sediments from 200 dry IRES reaches spanning multiple biomes. Results from standardized assays show that mean respiration increased 32–66-fold upon sediment rewetting. Structural equation modelling indicates that this response was driven by sediment texture and organic matter quantity and quality, which, in turn, were influenced by climate, land use and riparian plant cover. Our estimates suggest that respiration pulses resulting from rewetting of IRES sediments could contribute significantly to annual CO2 emissions from the global stream network, with a single respiration pulse potentially increasing emission by 0.2–0.7%. As the spatial and temporal extent of IRES increases globally, our results highlight the importance of recognizing the influence of wetting-drying cycles on respiration and CO2 emissions in stream networks., We thank Y. Etxeberria, L. Sánchez, C. Gutiérrez, G. LeGoff and B. Launay for laboratory support. DvS was supported by a Short-Term Scientific Mission of the COST Action CA15113 (SMIRES, Science and Management of Intermittent Rivers and Ephemeral Streams, www.smires.eu), supported by COST (European Cooperation in Science and Technology) and received additional funding from the EU’s 7th Framework Programme for research, technological development and demonstration under grant agreement No. 603629 (GLOBAQUA) and a Grant for Research Groups of the Basque University System (IT-951-16) funded by the Basque Government. RM and BO were supported by the Spanish Ministry of Science, Innovation and Universities through project C-HYDROCHANGE (CGL2017-86788-C3-2-P and CGL2017-86788-C3-3-P). FA was funded by the Swiss National Science Foundation grants No. PP00P3_150698 and PP00P3_179089. NC was supported by the EU project LIFE+ TRivers (LIFE13 ENV/ES/000341). SDL received funding from the EU’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 748625. PP and MP were supported by INTER-COST project LTC17017. The authors declare that they have no competing interests.

In this research, 558 family timber-frame houses newly built in the period of 2006–2019 in the Czech Republic were assessed in terms of their airtightness. The air leakage through the building envelope was evaluated via the ‘blower-door’ method, and the most important parameters affecting the airtightness of these types of buildings were simultaneously evaluated. In low-energy houses with natural ventilation, the mean air change rate at a pressure difference of 50 Pa (ACH50) was ascertained as 1.03 h−1, and in low-energy houses with mechanical ventilation and heat recovery, the average ACH50 value was 1.07 h−1. Passive houses had an average ACH50 value of 0.44 h−1. The positive effects of mandatory regulations and government subsidies were demonstrated. The ACH50 values improved with each new year of construction; this trend was especially evident for low-energy houses. A very significant influence was also found from the company conducting the construction and the construction technology being employed; an on-site construction method achieved lower ACH50 values than a method based on panel construction with a higher degree of prefabrication. The ACH50 values were also affected by the presence of a chimney and/or type of the interior airtight vapour barrier. In particular, a brick chimney body impaired the ACH50 values. Timber-frame houses with a vapour-permeable air barrier systems generally had smaller air leakage rate values than houses with a polyethylene vapour barrier. However, neither the internal building volume nor the envelope area were found to be significant parameters in terms of airtightness for the lightweight timber-frame residential houses.

The aim of this article is to acquaint the professional public with the summary results of the assessment of chemical status and ecological status/potential of surface water bodies “river” and “lake” categories in the Czech Republic for 2016–2018. This assessment is one from the basis for preparation of the Third River Basin Management Plan (2021–2027) at all its levels: sub-basin plans, national plans, and international plans of the Elbe, Danube, and Oder river basin districts.

We provide the first commented checklist of Armenian mayflies, based on all relevant literature and recent extensive sampling of 72 localities throughout Armenia during 2011, 2014, and 2015. Altogether 46 species are listed, eight of them reported from Armenia for the first time. One new species, Ecdyonurus (Ecdyonurus) eurycephalus sp. nov. is described (larva and male imago) based on morphological and molecular (COI) data. The species is characterized by a unique head shape in male imago and by the presence of tracheal filaments on gill plate VII in the larval stage.

International audience; Perennial rivers and streams make a disproportionate contribution to global carbon (C) cycling. However, the contribution of intermittent rivers and ephemeral streams (IRES), which sometimes cease to flow and can dry completely, is largely ignored although they represent over half the global river network. Substantial amounts of terrestrial plant litter (TPL) accumulate in dry riverbeds and, upon rewetting, this material can undergo rapid microbial processing. We present the results of a global research collaboration that collected and analysed TPL from 212 dry riverbeds across major environmental gradients and climate zones. We assessed litter decomposability by quantifying the litter carbon-to-nitrogen ratio and oxygen (O2) consumption in standardized assays and estimated the potential short-term CO2 emissions during rewetting events. Aridity, cover of riparian vegetation, channel width and dry-phase duration explained most variability in the quantity and decomposability of plant litter in IRES. Our estimates indicate that a single pulse of CO2 emission upon litter rewetting contributes up to 10% of the daily CO2 emission from perennial rivers and stream, particularly in temperate climates. This indicates that the contributions of IRES should be included in global C-cycling assessments.

Conformity Assessment of construction products is in accordance with EU concepts enabling free movement of goods within member states. The construction products (i.e. also construction product based on wood) which are liable to conformity assessment are listed in the Governmental Decree No. 312/2005 Coll. and Governmental Decree No. 190/2002 Coll. (technical requirements for construction products with CE marking). The European harmonised standards (both issued and prepared) have immediate influence on methodologies of Conformity Assessment. Methodologies and requirements on products during this process implicate also requirements on Notified Bodies and producers. The aim of the first stage of the research was to analyse the present state in this field and relations taking place during preparation and implementations of harmonised standards.

Correction to: Nature Geoscience https://doi.org/10.1038/s41561-018-0134-4, published online 21 May 2018. In the version of this Article originally published, the affiliation for M. I. Arce was incorrect; it should have been: 5Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany. This has now been corrected in the online versions of the Article.

The construction of water dams fundamentally changes nature and landscape not only in the flooded areas but also out of them, including all structures and links and leading to habitat loss. Three characteristically different South Moravian water reservoirs – the Vranov Dam, the Brno Dam and system of water reservoirs of Nove Mlýny have been studied in the project “Submerged cultural and natural heritage of South Moravia” (DF13P01OVV012) supported by the Ministry of Culture of the Czech Republic.

V ramci řeseni dilciho ukolu Zhodnoceni dopadů sucha v utvarech povrchových vod na vodni a vodu vazane organismy projektu zahrnujici cinnosti k podpoře výkonu statni spravy v problematice sucho v roce 2016 byla zpracovana zejmena resersni analýza potencialniho vlivu sucha na jednotlive složky a ukazatele hodnoceni stavu vodnich utvarů jako prostředku pro hodnoceni kvality vodnich ekosystemů.