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Construction of dams and transformation of rivers, not only affects river-related and adjacent habitats, but also establishes new threats to surface freshwater resources globally. Predicted climate changes and increase of mean annual temperature will affect thermal regimes of dam reservoir ecosystems, severely altering their functioning. Analyzing three projections of representative concentration pathway (RCP 4.5, 6.0 and 8.5) for period of 2061-2080, we found that mean annual temperature at dam reservoir locations will increase by 3.06 °C to 4.74 °C from present. The highest projected increase of temperature was identified for dam reservoirs located in high latitudes of Northern Hemisphere, and therefore dam reservoirs located there will be most significantly affected. Numerous consequences of temperature increase are already recorded. Further increase will amplify unfavorable effects on numerous ecosystems, including dam reservoirs which are built on the purpose of the human population development. Our study indicates a threat for artificially stored water globally, with special attention to high latitudes in northern hemisphere and latitudes close to 20

This study analyzed the enemy release hypothesis (ERH) assumptions under different climatic conditions in a lowland region and a mountain region in Poland. A common garden experiment was performed in 2010 and 2011 using 3 native (Impatiens noli-tangere, Solidago virgaurea, and Polygonum bistorta), 2 noninvasive alien (Impatiens walleriana and Impatiens balsamina), and 4 invasive alien (Impatiens glandulifera, Impatiens parviflora, Solidago gigantea, and Reynoutria japonica) species. The species were surveyed for leaf damage and invertebrate pest attacks. In all tests, leaf damage and pests were recorded more frequently in the lowland than in the mountains. The differences were particularly evident in the models for Impatiens and in the leaf damage model for Solidago. The distinction was irrelevant for some species (Polygonaceae); however, these results should be interpreted with caution because the taxonomic relations between the studied Polygonaceae were lower than those between the other tested species. Considering all the tests, the assumptions of the ERH hypothesis were confirmed in 6 cases (29%), whereas there was no confirmation in 15 cases, including 7 cases of nonsignificance and 8 cases of the opposite results. Moreover, the overall result of the comparison between the noninvasive and invasive alien species was the opposite of that predicted by the ERH hypothesis; in more than 2/3 of the cases, invasive alien species were released from the enemy less effectively than were noninvasive ones. In conclusion, the assumptions of the ERH hypothesis do not always hold true, and the invasion success of alien species may depend on several factors, including specific local conditions.

‘Algae Service for LIFE’, the project supported by the European Union, seeks to promote best practices in ecological service and the circular economy by implementing innovative complex system of three interlinked elements: i) prototypes for harvesting of cyanobacteria and macroalgae biomass; ii) distant methods for surveying of the blooms and defining hot-spots of algal agglomerations; and iii) restitution of harvesting costs by redesigning of waste algal biomass into valuable products. The current paper describes application of algal biomass part of the project by providing actions in redesigning of harvested waste biomass of cyanobacteria and macroalgae into potential valuable products for sustainable management and recycling of environmental resources. It also highlights the socio-economic aspects of the project and added value of the project for the European Union.

Global warming and eutrophication are the main factors driving the development of cyanobacterial dominance in aquatic ecosystems. We used a model linking water temperature, oxygen saturation, concentrations of PO43−, NO3−, NH4+, total dissolved iron (TDFe), and SO42− to cyanobacteria to test the turnover patterns of cyanobacterial dominance of non-nitrogen-fixing (chroococcal species) and nitrogen-fixing (filamentous diazotrophic) species. Statistical analysis was performed using decision trees. The dominance patterns of the two morphologically and ecologically distinct cyanobacterial species were associated with different environmental factors. However, SO42− was the most important factor that explained whether non-nitrogen-fixing or nitrogen-fixing species would dominate. Other important factors were water temperature, phosphate concentration, and oxygen saturation. The model for dominance of non-nitrogen-fixing species used SO42−, PO43−, and water temperature (upper layers), and SO42−, the ratio of PO43−/NH4+, and oxygen saturation (bottom layers). In contrast, water temperature, SO42−, and NH4+ in the upper layers and SO42−, NH4+, and water temperature in the bottom layers were used for the dominance of nitrogen-fixing species. The dominance of Aphanizomenon flos-aquae was explained by different sets of variables, indicating the presence of different strains of this species. The other cyanobacteria species showed dominance patterns that could be explained by one set of variables. As cyanobacterial blooms proliferate due to climate change, it is important to know which factors, in addition to phosphorus and nitrogen, are crucial for the mass development of the various cyanobacterial species.

In the twentieth century the heavily channelized Raba River incised deeply in its mountain course. Abandonment of channelization structures in a 2.3-km-long reach within a forested corridor was followed by considerable channel widening during floods of 30- and 35-year recurrence interval, re-establishment of a multi-thread channel pattern and island development. Morphological and botanical surveys were conducted annually between 2011 and 2017 to determine the processes and patterns governing development of islands and their floristic complexity. Hydraulic conditions promoting establishment and persistence of islands were determined with one-dimensional hydraulic modelling of flood flows for 8 unmanaged river cross-sections with islands and 8 cross-sections in the adjacent channelized reaches. Average age, number of islands and their average and total area in the reach markedly increased over the study period. However, the increase was not steady but moderated by island erosion by flood flows, island establishment shortly after major floods and island coalescence in the years without such floods. Hydraulic modelling indicated that river cross-sections with islands are typified by significantly lower values of mean water depth, flow velocity, unit stream power and bed shear stress at flood flows than cross-sections in the adjacent, channelized reaches. Such conditions promote deposition of living driftwood on channel bars, initiating island development, and reduce the probability of erosion of existing islands. The total number of plant species on islands varied highly and either exceeded or was similar to that recorded on riparian forest plots in particular years. This study indicates that (i) island re-establishment in the river was initiated by substantial channel widening, (ii) variation in flood magnitudes exerts a considerable influence on the trajectory of island development, and (iii) the contribution of islands to the overall species richness of plant communities in the river corridor at early stages of island re-establishment may be highly varied.

Small waterbodies and oxbow lakes play an important role as hotspots of biodiversity and landscape diversity, supplying a range of ecosystem services. However, they are at risk of disappearing. Thus, there is a need for the threats to their existence to be recognised. In this study we aimed to determine whether land uses within small and larger areas around these waterbodies, combined with selected two abiotic factors (pH, conductivity), affect the “characteristic combination of macrophytes”, which is the main indicator of status conservation of such waterbodies. We surveyed 113 Polish oxbow lakes within the floodplains of 16 rivers. Based on ordination analysis (NMDS db-RDA) we found significant differences in the conservation status of macrophyte assemblages between waterbodies with arable land close by and those with woody and shrub vegetation; also affecting the conservation status of the aquatic plant assemblages were meadows, forests, and water pH. For larger environs the conservation status of the aquatic plant assemblages was affected by land use types (urban, mines and excavations, meadows, forests) and by water pH. Our findings prove that conservation programs of oxbow lakes, ponds and small waterbodies should be based on protection and preservation of their immediate and larger surroundings, as well.

The authors acknowledge COST Action ES 1105 "CYANOCOST Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management" and COST Action Global Change Biology ES 1201 NETLAKE -Networking Lake Observatories in Europe" for contributing to this study through networking and knowledge sharing with European experts in the field. We acknowledge the members of the Global Lake Ecological Observatory Network (GLEON) for their collaborative spirit and enthusiasm that inspired the grassroots effort of the EMLS. E.M. was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation to Bas Ibelings and by supplementary funding from University of Geneva. We thank Wendy Beekman for the nutrient analysis. We thank Pieter Slot for assisting with the pigment analysis. We thank Dr. Ian Jones for valuable feedback on an earlier version of the manuscript. We thank the Leibniz Institute of Freshwater Ecology and the Aquatic Microbial Ecology Group for logistic and technical support of J. Fonvielle and H.-P. Grossart, and the Leibniz Association for financial support. H.P. was supported by the US National Science Foundation (1840715, 1831096). A.C.'s work was funded by the Spanish Agencia Estatal de Investigacion and EU funds through the project CLIMAWET (CGL2015-69557-R). The collection of data for Lough Erne and Lough Neagh were funded by the Department of Agriculture, Environment and Rural Affairs, Northern Ireland. We are grateful to Kristiina Vuorio from the Freshwater Centre of the Finnish Environment institute for her help in organizing, collecting and analysing samples by the University of Jyvaskyla and to Gerald Dorflinger from the Water Development Department of Cyprus for his assistance with the sampling in Cyprus and for granting the CUT team permission to use WDD's equipment. Finally, we would like to thank the numerous other assistants that helped realizing each local survey. Open access funding provided by Universite de Geneve., To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L-1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 degrees C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature., European Cooperation in Science and Technology (COST) ES 1105 ES 1201, Swiss State Secretariat for Education, Research and Innovation, University of Geneva, Leibniz Association, National Science Foundation (NSF) 1840715 1831096, Spanish Agencia Estatal de Investigacion, European Commission CGL2015-69557-R, Department of Agriculture, Environment and Rural Affairs, Northern Ireland

Development of human population is linked to drastic transformations of natural habitats, often resulting in significant losses in biodiversity. One element of this land usage which is inextricably linked with human settlement are cemeteries. Numerous species planted in cemeteries are alien, and as a result, cemeteries can act as hubs of alien plant species invasions. The aim of our study was to examine the relation between cemeteries, their surroundings (i.e. the area in the immediate vicinity of the cemetery) and alien plant species occurrence. We hypothesised that highly disturbed land in surrounding of the cemetery provides increased opportunity for alien plant species to invade. We studied 32, cemeteries and their surroundings located in southern Poland. The cemeteries were divided into three groups, based on the land use of their surroundings: highly disturbed, semi-natural, and natural. We found 138 alien plant species present in the studied cemeteries, 43 (31.1 %) of which are classified as invasive in Poland. We did not find statistically significant differences in the number of alien plant species present in the cemeteries (between identified groups). However, the analyses showed that the number of alien plant species present both in the cemetery and its surroundings was higher in cemeteries with ‘disturbed’ surroundings than in cemeteries with ‘natural’ surroundings. Our study shows that cemeteries can be hubs for alien plant species dispersal. To decrease chance of invasion by alien plant species planted in cemeteries the authorities and managers should seek opportunities to maintain or improve biodiversity and ecosystem functioning of habitats around cemeteries.

The diversity of rotifers was studied in three artificial water bodies (Azure Lake, Yellow Lake, and Purple Lake), which were once pyrite mines. The physicochemical parameters and the zooplankton composition of the water were determined. Azure Lake had a pH of 3.4–6.9, conductivity values of 165–194 µS cm− 1, and low concentrations of sulphate, calcium, magnesium, copper, and iron, while the other lakes had a pH of 2.6–2.9, a conductivity of 1636–3400 µS cm− 1, and high concentrations of sulphate (up to 2863 mg dm− 3), Cu (up to 2650 µg dm− 3), and Fe (up to 178.3 mg dm− 3). The rotifer community in the lakes comprised 27 taxa (15 in Azure Lake, 13 in Purple Lake and 14 in Yellow Lake). We also found two species that are rarely observed in Poland (Aspelta cincinator and Elosa spinifera), and three species commonly found in acidic water (E. worallii, Cephalodella delicata, and C. hoodi). The types of rotifers in Azure Lake differed from those in the other two lakes. The Shannon–Weaver biodiversity index (H′) was the highest in Purple Lake (H′ = 1.255) and lowest in Azure Lake (H′ = 0.455). The effect of some of the physicochemical parameters on rotifer diversity is discussed.

Water samples from the different basins of the Baltic Sea and North Sea were collected during four cruises taken place in 2016–2017. Altogether 60 water samples for 3H activity concentration and 120 water samples for stable isotopes ratio (δ18O and δ2H) were analysed. Exceptionally strong inflow activity from North Sea to the Baltic Sea occurred prior our surveys. The data obtained enabled comprehensive evaluation of tritium and stable isotopes distribution in waters of Baltic Sea and contributing inputs, including riverine and atmospheric freshwater flux and saline water inflow through the Danish Straits. By comparing with the previous studies, we noticed a tendency toward an increase in the δ18O and δ2H values of zero-salinity component over time, which may be due to climate change. In the case of tritium, the influence of artificial sources has also been noticed., Europos Sąjungos LIFE programos projektas „Algae Service for LIFE“ skatina gerąją ekologinių paslaugų praktiką ir žiedinės ekonomikos kūrimą. Projekto tikslas yra demonstruoti integruotą efektyvų maistinių medžiagų ir dumblių „žydėjimų“ valdymą upių baseinų lygyje, surenkant perteklinę melsvabakterių ir makrodumblių biomasę iš skirtingų vandens telkinių (upių, ežerų, tvenkinių, Kuršių marių). Taip pat projektu siekiama skleisti informaciją nacionalinėms ir vietos valdžios institucijoms, verslo bendruomenei bei didinti visuomenėssusidomėjimą vandens telkinių ekologine būkle. Straipsnyje aptariamos ekologinės vandens „žydėjimų“ kontrolės priemonės ir paslaugos, akcentuojant gėlavandenių ekosistemų eutrofikacijos ir „žydėjimų“ priežastis ir pasekmes. Siūlomos projekte priemonės prisideda prie Europos Sąjungos strateginių direktyvų įgyvendinimo.

The authors tested the hypothesis that zooplankton diversity and density are affected by the presence of cyanotoxins in the water. The authors focused on 4 oxbow lakes of the Vistula River in southern Poland, which are subjected to mass cyanobacterial development. In 2 of the oxbows (Piekary and Tyniec), microcystins released into the water were found. The highest concentration of microcystins (0.246 μg/L) was observed for microcystins LR. Zooplankton diversity showed a weak response to the presence of microcystins released into the water. The Shannon index (H') of total zooplankton diversity decreased in the Piekary and Tyniec oxbows during periods when the microcystin concentrations were highest. The same trend was noted for diversity of rotifers in both oxbows and for diversity of copepods in Piekary, but not for copepods in Tyniec. No such trends were found for the diversity of cladocerans in any of the oxbows, nor was a relationship found between density of zooplankton and microcystins. Statistical analyses showed that the number of species in individual samples was negatively correlated with the levels of sulfates, phosphates, and ammonia, but the microcystin concentration was positively related to those levels. This points to the complexity of the interactions and synergies among toxins, abiotic factors, and zooplankton biodiversity. In focusing on the problem of cyanotoxins, conservation studies should pay attention to this complexity. Environ Toxicol Chem 2017;36:165–174. © 2016 SETAC

Traditional methods of quantifying the harmful effects of invertebrates on plants require time-consuming identification of large numbers of individuals at species level. Collected specimens usually are killed; this may be unacceptable for some strictly protected species and may bias the results of subsequent surveys at the same site.We developed a “harmfulness scale” for quick, non-invasive assessment of invertebrate impacts on plants, and used the scale to test differences in invertebrate attack on species of Balsaminaceae, Polygonaceae and Asteraceae growing in lowland and mountains in Poland. In 2010–2011, we recorded 9190 invertebrates and identified them in situ to family or superfamily level. Among them were 7593 pests, accounting for 82.6% of all recorded organisms. Pests were three times more numerous in the mountains than in the lowland. Balsaminaceae were most heavily attacked by pests (92.9% of all organisms detected on them). Aphidoideae were the most numerous pests.This method can hel...

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains. © 2018 by the authors. Licensee MDPI, Basel, Switzerland., The authors acknowledge COST Action ES 1105 “CYANOCOST—Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management” and COST Action ES 1201 “NETLAKE—Networking Lake Observatories in Europe” for contributing to this study through networking and knowledge sharing with European experts in the field. Evanthia Mantzouki was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation (SERI) to Bas Ibelings and by supplementary funding from the University of Geneva. We thank Clare Ahnlund, Ena Suarez and Irene Gallego for helping out with the Swiss survey. We thank Wendy Beekman and Els J. Faassen for the nutrient and toxin analysis.

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment., The authors acknowledge COST Action ES 1105 “CYANOCOST – Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management” and COST Action ES 1201 “NETLAKE – Networking Lake Observatories in Europe” for contributing to this study through networking and knowledge sharing with European experts in the field. Evanthia Mantzouki was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation (SERI) to Bas Ibelings and by supplementary funding from University of Geneva. We thank Wendy Beekman for the nutrient analysis and the University of Wageningen for covering the costs of this analysis from the personal funding of dr. Miquel Lürling. We thank Pieter Slot for assisting with the pigment analysis and the University of Amsterdam for covering the costs of the analysis through funding from the group of Prof. Jef Huisman and dr. Petra Visser (IBED). We would like to thank the Environmental Data Initiative for covering the cost of archiving the EMLS dataset. We would like to thank the Leibniz Institute of Freshwater Ecology and Inland Fisheries, Dept. of Experimental Limnology and the Aquatic Microbial Ecology Group for logistic and technical support of J. Fonvielle and H.-P. Grossart; and the Leibniz Association for financial support. The collection of data for Lough Erne and Lough Neagh were funded by the Department of Agriculture, Environment and Rural Affairs, Northern Ireland.

Vegetated islands are characteristic landforms of braided mountain rivers. Long-term observations and recent morphological and botanical surveys conducted in the gravel-bed Czarny Dunajec, Polish Carpathians, were used to determine the processes and patterns governing initiation and development of islands and their floristic complexity. Moreover, dendrochronologically estimated years of island inception were compared with the timing and magnitude of flood flows in the period 1970–2011 to infer about controls on the formation and persistence of islands in the river. In the high-energy, braided river, islands originate as a result of deposition of large vegetative particles, mostly large wood, on gravel bars and the associated vegetative regeneration of living wood or the growth of seedlings and saplings in the shelter of wood accumulations. Tree-ring dating of the largest trees growing in particular zones of building and established islands indicated a predominant upstream island growth in the river. It results from repeated accumulation of living wood on the head of islands and its subsequent regeneration and contrasts with the progressive downstream growth of islands in the rivers supplied with large, stable logs of the tree species without the capability to re-sprout. The lack of islands from the years 1982–1996 most likely reflects the removal of relatively young islands by two major floods in the 1990s which were, however, unable to destroy older and larger islands. After 1997 the occurrence of low to moderate floods facilitated the formation and persistence of islands. The plant inventory demonstrated that species richness increased non-linearly with the increasing age, area and shoreline length of islands. Islands supported more plant species than the riparian forest and attained comparable species richness at an early stage of development. Fast developing, dynamic and supporting rich plant communities, islands contribute highly to the overall floristic complexity of the river corridor and their re-establishment should be viewed as an important factor in the restoration of hydromorphologically degraded mountain rivers.

This investigation focused on plankton inhabiting fishponds, which previously received mine waters from the lead-zinc mine ‘Matylda’, located in southern Poland (Upper Silesia). The purpose of the investigation was to study the effects of chronic and persistent contamination of fishpond bottom sediments with heavy metals originated from the lead and zinc mine. The phyto-and zooplankton in the four fishponds were dominated by diatoms, green algae and rotifers. Plankton composition of the reference non-contaminated pond was different, since Chrysophytes dominated, and Copepoda were the most numerous among zooplankton. In the contaminated fishponds, we observed teratological forms, both for phyto-and zooplankton species, but only as individuals. Our results showed that planktonic communities had adapted to chronic and persistent heavy metal contamination.

The aim of this study was to determine the relationships in the microbial trophic network underpinning them about communities of plankton ciliates in shallow oxbow lakes of the Vistula River in southern Poland (Jeziorzany 1, Jeziorzany 2, Piekary, Tyniec). The plankton components (phytoplankton, ciliates, zooplankton) were grouped by dietary preference. The studied oxbows differed in physicochemical parameters and in phytoplankton. Cyanobacteria dominated in the total biomass of phytoplankton in the Tyniec oxbow, big green algae (>30 μm) in Piekary and Jeziorzany 1, and euglenoids in Jeziorzany 2 oxbow. The dominance pattern of ciliates and zooplankton were similar in all oxbows. Algivorous ciliates were the main dominant ciliates, and among zooplankton the dominant ones were herbivores that feed on small algae (30 μm). There was no significant differences in ciliate biomass between oxbows. In redundancy analyses, the variability at the trophic groups of plankton was described by explanatory variables in 42.3 %, and positive relationships were found: e.g., between omnivorous zooplankton biomass, the biomass of ciliates feeding on bacteria + algae, and NH4 level; between euglenoid biomass and dinoflagellate biomass; and between cyanobacteria biomass and bacterivorous ciliate biomass. Spearman correlation analysis revealed several relationships between different groups of plankton. In general, phytoplankton group shows more connection among themselves and with different zooplankton groups, e.g., phytoplankton biomass with herbivorous zooplankton biomass (−0.33); and cyanobacteria biomass with dinoflagellate biomass (0.65). Ciliates showed more connections among their trophic groups (e.g., algivorous ciliate biomass with omnivorous ciliate biomass, 0.78) and with zooplankton trophic groups (e.g., biomass of algivorous + bacterivorous ciliates with biomass of predator zooplankton, −0.36). Simple correlations analysis revealed the trophic food web network connectivity among plankton organisms, indicating the flow of organic matter from phytoplankton to zooplankton and from ciliates to zooplankton. Our study sheds light on the trophic relations among plankton ciliates, which are neglected in research but often form a large percentage of zooplankton biomass. In the studied oxbows, ciliate forms 6.7 % of total zooplankton biomass in Jeziorzany 1 and up to 44.5 % of it in the Piekary oxbow.