Invasion impacts and dynamics of a European-wide introduced species.

Globalization has led to the introduction of thousands of alien species worldwide. With growing impacts by invasive species, understanding the invasion process remains critical for predicting adverse effects and informing efficient management. Theoretically, invasion dynamics have been assumed to follow an "invasion curve" (S-shaped curve of available area invaded over time), but this dynamic has lacked empirical testing using large-scale data and neglects to consider invader abundances. We propose an "impact curve" describing the impacts generated by invasive species over time based on cumulative abundances. To test this curve's large-scale applicability, we used the data-rich New Zealand mud snail Potamopyrgus antipodarum, one of the most damaging freshwater invaders that has invaded almost all of Europe. Using long-term (1979-2020) abundance and environmental data collected across 306 European sites, we observed that P. antipodarum abundance generally increased through time, with slower population growth at higher latitudes and with lower runoff depth. Fifty-nine percent of these populations followed the impact curve, characterized by first occurrence, exponential growth, then long-term saturation. This behaviour is consistent with boom-bust dynamics, as saturation occurs due to a rapid decline in abundance over time. Across sites, we estimated that impact peaked approximately two decades after first detection, but the rate of progression along the invasion process was influenced by local abiotic conditions. The S-shaped impact curve may be common among many invasive species that undergo complex invasion dynamics. This provides a potentially unifying approach to advance understanding of large-scale invasion dynamics and could inform timely management actions to mitigate impacts on ecosystems and economies.

Long-term effects of climate change on carbon storage and tree species composition in a dry deciduous forest.

Forest vegetation and soils have been suggested as potentially important sinks for carbon (C) with appropriate management and thus are implicated as effective tools in stabilizing climate even with increasing anthropogenic release of CO2 . Drought, however, which is often predicted to increase in models of future climate change, may limit net primary productio (NPP) of dry forest types, with unknown effects on soil C storage. We studied C dynamics of a deciduous temperate forest of Hungary that has been subject to significant decreases in precipitation and increases in temperature in recent decades. We resampled plots that were established in 1972 and repeated the full C inventory by analyzing more than 4 decades of data on the number of living trees, biomass of trees and shrubs, and soil C content. Our analyses show that the decline in number and biomass of oaks started around the end of the 1970s with a 71% reduction in the number of sessile oak stems by 2014. Projected growth in this forest, based on the yield table's data for Hungary, was 4.6 kg C/m2 . Although new species emerged, this new growth and small increases in oak biomass resulted in only 1.9 kg C/m2 increase over 41 years. The death of oaks increased inputs of coarse woody debris to the surface of the soil, much of which is still identifiable, and caused an increase of 15.5%, or 2.6 kg C/m2 , in the top 1 m of soil. Stability of this fresh organic matter input to surface soil is unknown, but is likely to be low based on the results of a colocated woody litter decomposition study. The effects of a warmer and drier climate on the C balance of forests in this region will be felt for decades to come as woody litter inputs decay, and forest growth remains impeded.

A real-world study of quality of life following treatment with xylometazoline hydrochloride in individuals with common cold.

BACKGROUND: The common cold is a frequent, acute, and mild upper respiratory human disease. Nasal congestion has been considered the most bothersome symptom in the common cold, impacting quality of life (QoL). Topical decongestants containing steroids benefit QoL in allergic rhinitis, but no published research has assessed the impact of topical decongestants on QoL in the common cold. OBJECTIVE: To evaluate the effects of xylometazoline hydrochloride 0.1% (Otrivin, GSK Consumer Healthcare SARL, Switzerland) for up to 7 days on QoL in participants with nasal congestion associated with the common cold. DESIGN: This was a decentralized, longitudinal, open-label study. METHODS: The study enrolled 136 participants (⩾18 years) with early symptoms of the common cold, of which 102 were included in the modified intention-to-treat (mITT) population. Within 24 h of study product receipt, participants confirmed a 'plugged nose' and ⩾1 other common cold symptom. Primary endpoints were Wisconsin Upper Respiratory Symptom Survey-21 (WURSS-21) total score, total and individual symptom scores, and total QoL score. Secondary endpoints were additional QoL scores. Exploratory and post hoc analyses included median days to resolution for each QoL factor and analyses of five QoL categories. RESULTS: Consistent improvements in symptoms and QoL were seen in the mITT population. From day 1, improvements were seen in the 'plugged nose' symptom (p = 0.0023), WURSS-21 total QoL score, and all individual QoL scores (p < 0.0001 for all). After the last dose needed, significant improvements were seen in sleep quality (73%), vitality (76%), physical activity (71%), social activity (80%), and sensation (81%). No serious or unexpected adverse events were reported. CONCLUSION: This study is the first to demonstrate in a real-life setting that treating nasal congestion in adults with xylometazoline hydrochloride 0.1% during the common cold positively impacts QoL factors relevant to daily living [Otrivin: Quality of Life (QoL) Impact in a Real-World Setting; https://clinicaltrials.gov/study/NCT05556148].

Impact of xylometazoline hydrochloride 0.1% on quality of life in people with blocked nose associated with the common coldThe common cold is a widespread, mild respiratory illness for which a hallmark symptom is a blocked or stuffy nose, which makes breathing and sleeping difficult. This study focused on how a nasal spray called Otrivin (containing xylometazoline hydrochloride 0.1%) impacts the quality of life (QoL) of people suffering from nasal congestion due to the common cold.Participants answered a questionnaire called the Wisconsin Upper Respiratory Symptom Survey-21 (WURSS-21), which helped understand how people experience respiratory symptoms and how different aspects of QoL were impacted. Participants also responded to eight additional QoL questions not covered in the WURSS-21.The results showed that from the first day of using the nasal spray, participants experienced significant relief from the blocked nose symptom and reported an overall improvement in their QoL and well-being, such as in sleep quality, energy levels, senses, and physical and social activities.In conclusion, this real-world study demonstrated that using xylometazoline hydrochloride 0.1% nasal spray during the common cold can significantly improve nasal congestion and various aspects of a person's daily life. These findings provide valuable evidence for using this nasal spray to relieve symptoms and enhance the overall well-being of individuals with the common cold.

Setting nutrient boundaries to protect aquatic communities: The importance of comparing observed and predicted classifications using measures derived from a confusion matrix.

Defining nutrient thresholds that protect and support the ecological integrity of aquatic ecosystems is a fundamental step in maintaining their natural biodiversity and preserving their resilience. With increasing catchment pressures and climate change, it is more important than ever to develop clear methods to establish thresholds for status classification and management of waters. This must often be achieved using complex data and should be robust to interference from additional pressures as well as ameliorating or confounding conditions. We use both artificial and real data to examine challenges in setting nutrient thresholds in unbalanced and skewed data. We found significant advantages to using binary logistic regression over other techniques. However, one of the key challenges is objectively selecting a probability from which to derive the nutrient threshold. For this purpose, the examination of the proportions of matching and mismatching status classifications of nutrients and a biological quality element using a confusion matrix is a key step that should be more widely adopted in threshold selection. We examined a large array of statistical measures of classification accuracy and their performance over combinations of skewness and imbalance in the data. The most appropriate threshold probability is a compromise between maximising overall classification accuracy and reducing mismatches expressed as commission (false positives) without excessive omission (false negatives). An application to a lake type indicated total phosphorus thresholds that would be around 50 µg l-1 lower than the threshold achieved by an 'unguided' approach, indicating that this approach is a very significant development meriting attention from national authorities responsible for water management.

Inland navigation and land use interact to impact European freshwater biodiversity.

Inland navigation in Europe is proposed to increase in the coming years, being promoted as a low-carbon form of transport. However, we currently lack knowledge on how this would impact biodiversity at large scales and interact with existing stressors. Here we addressed this knowledge gap by analysing fish and macroinvertebrate community time series across large European rivers comprising 19,592 observations from 4,049 sampling sites spanning the past 32 years. We found ship traffic to be associated with biodiversity declines, that is, loss of fish and macroinvertebrate taxonomic richness, diversity and trait richness. Ship traffic was also associated with increases in taxonomic evenness, which, in concert with richness decreases, was attributed to losses in rare taxa. Ship traffic was especially harmful for benthic taxa and those preferring slow flows. These effects often depended on local land use and riparian degradation. In fish, negative impacts of shipping were highest in urban and agricultural landscapes. Regarding navigation infrastructure, the negative impact of channelization on macroinvertebrates was evident only when riparian degradation was also high. Our results demonstrate the risk of increasing inland navigation on freshwater biodiversity. Integrative waterway management accounting for riparian habitats and landscape characteristics could help to mitigate these impacts.

Long-Term Changes in Organic Matter Content and Soil Moisture Determine the Degree of Root and Soil Respiration.

Carbon in soil is one of the most important indicators of soil fertility. Part of the carbon stored in them is returned to the atmosphere during soil respiration. Climate change and inappropriate land use can accelerate these processes. Our work aimed to determine how soil CO2 emissions change over ten years as a result of litter manipulation treatments. Plots at the Síkfokút DIRT (Detritus Input and Removal Treatments) experimental site include doubling either leaf litter or wood, and removing all aboveground litter, all root inputs, or removing all litter inputs. With the help of this, we were able to examine not only the effects of the different organic matter intake but also the effects of the different microclimates that occur as a result of the treatments. Total soil respiration (root and microbial respiration) is a result of a persistent lack or excess of soil organic matter relative to soil moisture. Based on our studies, the increase in the intensity of root respiration on wetter soils was only half of the increase in respiration associated with decomposition activity. The sustained growth of leaf litter significantly increases soil respiration, which can be partly explained by the more favorable supply of nutrients to the decomposing organisms, and partly by the more favorable microclimatic conditions, however, these effects were only valid in the case of wetter soils. In the dry summer environment, we experienced higher CO2 emissions during litter removal treatments. In the first period between 2002 and 2004, even wetter root removal treatments showed a significantly higher CO2 emission, while in the period 2010-2012, surface litter removal treatments. The permanent removal of surface litter in the drier summer period resulted in the formation of a dense crack network, which increased the CO2 emission of these soils, which increases the soil organic carbon loss of the soil. Our study proves the advantages of mulching in terms of a more favorable microclimate of the soil surface and a balanced carbon balance of the soil-plant system.

Winners and Losers: Cordulegaster Species under the Pressure of Climate Change.

(1) Bioclimatic factors have a proven effect on species distributions in terrestrial, marine, or freshwater ecosystems. Because of anthropogenic effects, the changes in these variables are accelerated; thus, the knowledge of the impact has great importance from a conservation point of view. Two endemic dragonflies, the Balkan Goldenring (Cordulegaster heros) and the Two-Toothed Goldenring (C. bidentata), confined to the hilly and mountainous regions in Europe, are classified as "Near Threatened" according to the IUCN Red List. (2) Modeling the potential occurrence of both species under present and future climatic conditions provides a more accurate picture of the most suitable areas. The models were used to predict the responses of both species to 6 different climate scenarios for the year 2070. (3) We revealed which climatic and abiotic variables affect them the most and which areas are the most suitable for the species. We calculated how future climatic changes would affect the range of suitable areas for the two species. (4) According to our results, the suitable area for Cordulegaster bidentata and C. heros are strongly influenced by bioclimatic variables and showed an upward shift toward high elevations. The models predict a loss of suitable area in the case of C. bidentata and a large gain in the case of C. heros.

Characterisation of Luvisols Based on Wide-Scale Biological Properties in a Long-Term Organic Matter Experiment.

Soil organic matter is a biological system that functions as an integrated whole. These assemblies have different properties, functions, and decomposition times. SOM is one of the main determinants of soil productivity. Our studies were carried out in a temperate deciduous oak forest on Luvisols soil. In the DIRT Project (Detritus Input and Removal Treatments), the following treatments were applied: Double Litter, Double Wood, Control, No Litter, No Root and No Input. Our objective was to compare the effect of withdrawal or doubling of organic matter on the protein pattern of the soil and the biological activity and changes in labile C (permanganate-oxidizable carbon) content in a long-term organic matter manipulation experiment. Patterns of thermostable proteins, soil dehydrogenase enzyme activity, CO2 emission, and POXC content were measured at the most biologically active soil depth of 0-5 cm after 23 years of treatment. Our results show that the enzyme activities of the litter removal treatments were significantly reduced compared to the doubling treatments, as were the values of soil respiration. The same significant difference was also detected in the C content of the soils of the treatments. Based on cluster analysis of the protein profile of the soil samples, the No Litter and No Input treatments were significantly different from the other treatments. This shows that specific organic matter is needed to enhance soil biological activity and the associated POXC content.

River and lake nutrient targets that support ecological status: European scale gap analysis and strategies for the implementation of the Water Framework Directive.

Eutrophication caused by an excessive presence of nutrients is affecting large portions of European waters with more than 60% of the surface water bodies failing to achieve the primary ambition of water management in Europe, that of good ecological status (GES) with diffuse emission from agriculture being the second most important pressure affecting surface waters. We developed EU wide and regional nutrient targets that define the boundary concentrations between good and moderate status for river and lake total P (TP) and total N (TN) and assessed the gap between actual nutrient concentrations and these targets and considered strategies of nutrient reductions necessary to achieve GES and deliver ecosystem services. The nutrient targets established for rivers ranged from 0.5-3.5 mg/L TN and 11-105 µg/L TP and for lakes 0.5-1.8 mg/L TN and 10-60 µg/L TP. Based on the EU wide targets, 59% of the TN and 57% of the TP river monitoring sites and 64% of the TN and 61% of the TP lake monitoring sites exceed these value and are thus at less than GES. The PCA and step-wise regression for EU basins clearly showed that the basin nutrient export is predominantly related to agricultural inputs. In addition, the step-wise regression models for TN and TP provided the ability to extrapolate the results and quantify the input reductions necessary for reaching the nutrient targets at the EU level. The results suggest that a dual water management strategy would be beneficial and should focus a) on those less polluted rivers and lakes that can easily attain the GES goal and b) on the more highly polluted systems that will improve the delivery of ecosystem services.

Establishing ecologically-relevant nutrient thresholds: A tool-kit with guidance on its use.

One key component of any eutrophication management strategy is establishment of realistic thresholds above which negative impacts become significant and provision of ecosystem services is threatened. This paper introduces a toolkit of statistical approaches with which such thresholds can be set, explaining their rationale and situations under which each is effective. All methods assume a causal relationship between nutrients and biota, but we also recognise that nutrients rarely act in isolation. Many of the simpler methods have limited applicability when other stressors are present. Where relationships between nutrients and biota are strong, regression is recommended. Regression relationships can be extended to include additional stressors or variables responsible for variation between water bodies. However, when the relationship between nutrients and biota is weaker, categorical approaches are recommended. Of these, binomial regression and an approach based on classification mismatch are most effective although both will underestimate threshold concentrations if a second stressor is present. Whilst approaches such as changepoint analysis are not particularly useful for meeting the specific needs of EU legislation, other multivariate approaches (e.g. decision trees) may have a role to play. When other stressors are present quantile regression allows thresholds to be established which set limits above which nutrients are likely to influence the biota, irrespective of other pressures. The statistical methods in the toolkit may be useful as part of a management strategy, but more sophisticated approaches, often generating thresholds appropriate to individual water bodies rather than to broadly defined "types", are likely to be necessary too. The importance of understanding underlying ecological processes as well as correct selection and application of methods is emphasised, along with the need to consider local regulatory and decision-making systems, and the ease with which outcomes can be communicated to non-technical audiences.

Uncertainties of cell number estimation in cyanobacterial colonies and the potential use of sphere packing.

Cyanobacteria are notorious bloom formers causing various water quality concerns, such as toxin production, extreme diurnal variation of oxygen, pH, etc., therefore, their monitoring is essential to protect the ecological status of aquatic systems. Cyanobacterial cell counts and biovolumes are currently being used in water management and water quality alert systems. In this study, we investigated the accuracy of traditional colonial biovolume and cell count estimation approaches used in everyday practice. Using shape realistic 3D images of cyanobacterial colonies, we demonstrated that their shape cannot be approximated by ellipsoids. We also showed that despite the significant relationship between overall colony volume and cell biovolumes, because of the considerable scatter of cell count data the regressions give biased estimates for cyanobacterial cell counts. We proposed a novel approach to estimate cell counts in colonies that was based on the random close sphere packing method. This method provided good results only in those cases when overall colony volumes could be accurately measured. The visual investigation of colonies done by skilled experts has given precise but lower estimates for cell counts. The estimation results of several experts were surprisingly good, which suggests that this capability can be improved and estimation bias can be reduced to the level acceptable for water quality estimations.

Estimating nutrient thresholds for eutrophication management: Novel insights from understudied lake types.

Nutrient targets based on pressure-response models are essential for defining ambitions and managing eutrophication. However, the scale of biogeographical variation in these pressure-response relationships is poorly understood, which may hinder eutrophication management in regions where lake ecology is less intensively studied. In this study, we derive ecology-based nutrient targets for five major ecoregions of Europe: Northern, Central-Baltic, Alpine, Mediterranean and Eastern Continental. As a first step, we developed regressions between nutrient concentrations and ecological quality ratios (EQR) based on phytoplankton and macrophyte communities. Significant relationships were established for 13 major lake types; in most cases, these relationships were stronger for phosphorus than for nitrogen, and stronger for phytoplankton than for macrophytes. Using these regressions, we estimated the total phosphorus (TP) and total nitrogen (TN) concentrations at which lakes of different types are likely to achieve good ecological status. However, in the very shallow lakes of the Eastern Continental region, relations between nutrient and biological communities were weak or non-significant. This can be attributed to high nutrient concentrations (in the asymptotic zone of phosphorus-phytoplankton models) suggesting other factors (light, grazing) limit primary production. However, we also show that fish stocking is a major pressure on Eastern Continental lakes, negatively affecting ecological status: lakes with low fish stocking show low chlorophyll-a concentrations and good ecological status despite high nutrient levels, while the lakes with high fish stocking show high chlorophyll-a and low ecological status. This study highlights the need to better understand lakes in biogeographic regions that have been, for historical reasons, less studied. This, in turn, helps reveal factors that challenge the dominant paradigms of lake assessment and management.

Biovolume and surface area calculations for microalgae, using realistic 3D models.

Morphology and spatial dimensions of microalgal units (cells or colonies) are among the most relevant traits of planktic algae, which have a pronounced impact on their basic functional properties, like access to nutrients or light, the velocity of sinking or tolerance to grazing. Although the shape of algae can be approximated by geometric forms and thus, their volume and surface area can be calculated, this approach cannot be validated and might have uncertainties especially in the case of complicated forms. In this study, we report on a novel approach that uses real-like 3D mesh objects to visualize microalgae and calculates their volume and surface area. Knowing these dimensions and their intraspecific variabilities, we calculated specific shape and surface area constants for more than 300 forms, covering more than two thousand taxa. Using these constants, the accurate volume and surface area can be quickly computed for each taxon and having these values, morphology-related metrics like surface area/volume ratio, the diameter of spherical equivalent can also be given quickly and accurately. Besides their practical importance, the volume and surface area constants can be considered as size-independent morphological traits that are characteristic for the microalgal shapes, and provide new possibilities of data analyses in the field of phytoplankton ecology.

Cell Size Decrease and Altered Size Structure of Phytoplankton Constrain Ecosystem Functioning in the Middle Danube River Over Multiple Decades.

Reduced body size is among the universal ecological responses to global warming. Our knowledge on how altered body size affects ecosystem functioning in ectothermic aquatic organisms is still limited. We analysed trends in the cell size structure of phytoplankton in the middle Danube River over a 34-year period at multiple levels: (1) average cell size of assemblages (ACS), (2) within the centric diatom community and (3) in the dominant centric diatom taxon: Stephanodiscus. We asked whether global warming and human impacts affected the average cell size of phytoplankton. Also, whether the altered size structure affected how chlorophyll-a, as an ecosystem functioning measure, relates to the ACS of phytoplankton. The cell size of phytoplankton decreased significantly at all organisation levels, and the assemblages became more dispersed in cell size over time. Environmental variables related to global warming and human impacts affected the ACS of phytoplankton significantly. The relationship between chlorophyll-a and the ACS of phytoplankton shifted from negative linear to broad and then narrow hump shape over time. Longer water residence time, warming and decline in nutrients and suspended solids decrease the ACS of phytoplankton in the middle Danube and expectedly in other large rivers. Our results suggest that cell size decrease in phytoplankton, especially of centric diatoms, constrains planktic algal biomass production in large rivers, independently of algal density. Such cell size decrease may also affect higher trophic levels and enhance the more frequent occurrence of "clear-water" plankton in large, human-impacted rivers under global change.

Trait convergence and trait divergence in lake phytoplankton reflect community assembly rules.

Environmental filtering and limiting similarity are those locally acting processes that influence community structure. These mechanisms acting on the traits of species result in trait convergence or divergence within the communities. The role of these processes might change along environmental gradients, and it has been conceptualised in the stress-dominance hypothesis, which predicts that the relative importance of environmental filtering increases and competition decreases with increasing environmental stress. Analysing trait convergence and divergence in lake phytoplankton assemblages, we studied how the concepts of 'limiting similarity' versus 'environmental filtering' can be applied to these microscopic aquatic communities, and how they support or contradict the stress-dominance hypothesis. Using a null model approach, we investigated the divergence and convergence of phytoplankton traits along environmental gradients represented by canonical axes of an RDA. We used Rao's quadratic entropy as a measure of functional diversity and calculated effect size (ES) values for each sample. Negative ES values refer to trait convergence, i.e., to the higher probability of the environmental filtering in community assembly, while positive values indicate trait divergence, stressing the importance of limiting similarity (niche partitioning), that is, the competition between the phytoplankters. Our results revealed that limiting similarity and environmental filtering may operate simultaneously in phytoplankton communities, but these assembly mechanisms influenced the distribution of phytoplankton traits differently, and the effects show considerable changes along with the studied scales. Studying the changes of ES values along with the various scales, our results partly supported the stress-dominance hypothesis, which predicts that the relative importance of environmental filtering increases and competition decreases with increasing environmental stress.

Environmental filtering and limiting similarity as main forces driving diatom community structure in Mediterranean and continental temporary and perennial streams.

Climatic extreme events such as droughts (unpredictable), dry periods (predictable) or even flush floods, threaten freshwater ecosystems worldwide. The filtering mechanisms of these events and their strength on communities, however, can be different among regions. While time-for-adaptation theory defines whether or not water scarcity can be considered as disturbance, the stress-dominance theory predicts an increase in importance of environmental filtering and a decrease in the role of biotic interactions in communities with increasing environmental stress. Here, we tested whether environmental filtering (leading to trait convergence) or limiting similarity (leading to trait divergence) is the main assembly rule shaping the structure and trait composition of benthic diatom assemblages in Mediterranean (Portuguese) and continental (Hungarian) temporary and perennial streams. We assumed that the trait composition of diatom assemblages in the two stream types would be less different in the Mediterranean than in the continental region (addressed to time-for-adaptation theory). We also hypothesized that trait composition would be shaped by environmental filtering in the Hungarian streams while by biotic interactions in Portuguese streams (addressed to stress-dominance theory). Our results supported our first hypothesis since traits, which associated primarily to temporary streams were found only in the continental region. Our findings, however, only partially proved the stress-dominance hypothesis. In the continental region, where drying up of streams were induced by unpredictable droughts, biotic interactions were the main assembly rules shaping community structure. In contrast, environmental filtering was nearly as important as limiting similarity in structuring trait composition in the Mediterranean region during the predictable dry phase with no superficial flow. These analyses also highlighted that drought events (both predictable and unpredictable ones) have a complex and strong influence on benthic diatom assemblages resulting even in irreversible changes in trait composition and thereby in ecosystem functioning.

Groups of small lakes maintain larger microalgal diversity than large ones.

The question of whether one large, continuous area or many smaller habitats maintain more species is one of the most relevant questions in conservation ecology, and it is referred to as the SLOSS (Single Large Or Several Small) dilemma in the literature. This question has not yet been raised in the case of microscopic organisms, therefore we investigated whether or not the SLOSS dilemma could apply to phytoplankton and benthic diatom metacommunities. Benthic diatom and phytoplankton diversity in pools and ponds of different sizes (ranging between 10-2-107 m2) was studied. Species richness of water bodies belonging to neighbouring size categories was compared step by step across the whole size gradient. With the exception of the 104-105 m2 and 105-106 m2 size categories, where phytoplankton and benthic diatom richness values of the SL water bodies were higher than that of the SS ones, findings showed that the diversity of several smaller (SS) sized waters was higher than that in single large water bodies (SL) throughout the whole studied size range. The proportion of the various functional groups of algae, including both the benthic diatoms and phytoplankton, showed remarkable changes from the smaller water bodies to large sized ones.

DNA barcode reference libraries for the monitoring of aquatic biota in Europe: Gap-analysis and recommendations for future work.

Effective identification of species using short DNA fragments (DNA barcoding and DNA metabarcoding) requires reliable sequence reference libraries of known taxa. Both taxonomically comprehensive coverage and content quality are important for sufficient accuracy. For aquatic ecosystems in Europe, reliable barcode reference libraries are particularly important if molecular identification tools are to be implemented in biomonitoring and reports in the context of the EU Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD). We analysed gaps in the two most important reference databases, Barcode of Life Data Systems (BOLD) and NCBI GenBank, with a focus on the taxa most frequently used in WFD and MSFD. Our analyses show that coverage varies strongly among taxonomic groups, and among geographic regions. In general, groups that were actively targeted in barcode projects (e.g. fish, true bugs, caddisflies and vascular plants) are well represented in the barcode libraries, while others have fewer records (e.g. marine molluscs, ascidians, and freshwater diatoms). We also found that species monitored in several countries often are represented by barcodes in reference libraries, while species monitored in a single country frequently lack sequence records. A large proportion of species (up to 50%) in several taxonomic groups are only represented by private data in BOLD. Our results have implications for the future strategy to fill existing gaps in barcode libraries, especially if DNA metabarcoding is to be used in the monitoring of European aquatic biota under the WFD and MSFD. For example, missing species relevant to monitoring in multiple countries should be prioritized for future collaborative programs. We also discuss why a strategy for quality control and quality assurance of barcode reference libraries is needed and recommend future steps to ensure full utilisation of metabarcoding in aquatic biomonitoring.

Unexpected consequences of bombing. Community level response of epiphytic diatoms to environmental stress in a saline bomb crater pond area.

The spatial response of epiphytic diatom communities to environmental stress was studied in a moderately saline wetland area located in the plain of Danube-Tisza Interfluve, Hungary. The area is characterised by World War II bomb crater ponds and can be regarded as an excellent ecological model system where the dispersion of species is slightly limited by distance. To study the effect of environmental variables on the communities, canonical correspondence analysis was applied. Salinity, pH, total suspended solids, total phosphorous and depth proved to be significant environmental drivers in this analysis. The ecological status of the ponds was assessed with Ziemann's halobity index, as the trophity-depending metric cannot be applied to these habitats (due to the naturally high phosphorus content). Ponds in "good" ecological status significantly differed from those appertaining to water quality category of "not-good" ecological status considering characteristic of natural astatic soda pans (e.g. salinity, pH, ammonium, total phosphorous concentration, nitrogen:phosphorous ratio and turbidity). The differences between epiphytic diatom communities inhabiting the ponds were detected using non-parametric multidimensional scaling. The samples formed three groups according to the types of ponds ("transparent", "transitional" and "turbid") based on the width of the macrophyte belt around them. Indicator species related to the ecological status of the ponds and diatom communities contributing to the separation of groups of ponds were identified. One of the indicator species differed from species already described. Light and scanning electron microscopy features and phylogenetic analyses based on three genes (18S and 28S rRNA genes, rbcL) proved that it was a new species of Nitzschia genus, closely related to Nitzschia frustulum and Nitzschia inconspicua. Therefore, description of a new species, Nitzschia reskoi Ács, Duleba, C.E.Wetzel & Ector is proposed. We concluded that the increasing abundance of Nitzschia reskoi was a signal of the degradation of the intermittent saline wetlands.

Functional redundancy modifies species-area relationship for freshwater phytoplankton.

Although species-area relationship (SAR) is among the most extensively studied patterns in ecology, studies on aquatic and/or microbial systems are seriously underrepresented in the literature. We tested the algal SAR in lakes, pools and ponds of various sizes (10-2-108 m2) and similar hydromorphological and trophic characteristics using species-specific data and functional groups. Besides the expectation that species richness increases monotonously with area, we found a right-skewed hump-shaped relationship between the area and phytoplankton species richness. Functional richness however did not show such distortion. Differences between the area dependence of species and functional richness indicate that functional redundancy is responsible for the unusual hump-backed SAR. We demonstrated that the Small Island Effect, which is a characteristic for macroscopic SARs can also be observed for the phytoplankton. Our results imply a so-called large lake effect, which means that in case of large lakes, wind-induced mixing acts strongly against the habitat diversity and development of phytoplankton patchiness and finally results in lower phytoplankton species richness in the pelagial. High functional redundancy of the groups that prefer small-scale heterogeneity of the habitats is responsible for the unusual humpback relationship. The results lead us to conclude that although the mechanisms that regulate the richness of both microbial communities and communities of macroscopic organisms are similar, their importance can be different in micro- and macroscales.