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Zooplankton is a good indicator of water quality state. Analysing the species composition and abundance, it is possible to assess the condition of the water body and predict the direction of changes. The aim of the study was to analyse the zooplankton in a shallow urban lake, in which restoration was limited to one method, i.e. wind-aeration. The results were compared with the earlier data obtained during sustainable restoration (three methods: wind-aeration, phosphorus inactivation, biomanipulation) and before the restoration period. The zooplankton was sampled monthly in 2015 and 2016 in the deepest place of the lake from the surface to the bottom. The trophic state was determined based on rotifer trophic state index for lakes (TSIROT). Although the species composition of zooplankton communities varied very little among the restoration periods (Keratella cochlearis f. tecta mainly dominated), significant changes in the abundance of zooplankton were found in the analysed lake. The maximum of total abundance was noted in 2015, almost 5500 ind. L−1, and in the next year its decrease was almost 3-fold, to ca. 1800 ind. L-1. Based on TSIROT, the water was still eutrophic. Leaving only one method of restoration (namely, oxygenation of the bottom waters) proved insufficient to support the development of crucial organisms as cladocerans. The changes in the abundance could have resulted more from seasonal changes than from the effects of aeration. A reduction in species number and maintaining a high proportion of rotifers typical for a high trophic state indicated a return of the ecosystem to its pre-restoration state. High variability in the rotifer abundance indicated a continuous imbalance of the ecosystem. Previous restoration treatments using several methods simultaneously showed better effectiveness. The change of strategy of restoration before obtaining a stable improvement of water quality destroyed previously achieved effects.

To fill the knowledge gap about the functioning of the lake–river system subjected to restoration treatments, two tributaries, a shallow, restored lake and its outflow, were examined. The quality of water inflows, lake and outflow was compared before (BR), during sustainable (SR, deep water aeration, phosphorus inactivation and biomanipulation for 3 years) and limited lake restoration (LR, only aeration for 2 years). Physico-chemical parameters were analysed monthly at five stations. The nutrient concentrations at the inflows decreased over the years due to the improvement of water and sewage management in the catchment (in Mielcuch from 18.0 to 8.0 mgN L−1 and 1.0 to 0.6 mgP L−1). The decline at the outflow was the result of a better quality of water at the tributaries and SR in the lake. During LR, decrease of phosphorus concentration still occurred (0.11 mgP L−1), but nitrogen concentration slightly increased (3.9 mgN L−1). Although the outflowing waters still transported a high content of chlorophyll a and suspended solids during SR, their amount was lower (34.5 μg L−1 and 17 mg L−1, respectively) than that during BR and LR. During restoration, it is significant to monitor the water quality not only in the lake but also at the outflow. The slow deterioration of water quality at the outflow indicated that introducing changes in the applied restoration methods must be done carefully because the previously achieved effect may be lost. Hence, restoration of the upstream lake and good quality of its tributaries are of great importance for water bodies located downstream.

There is a pressing need to identify novel antiplatelet agents, an alternative to acetylsalicylic acid and thienopyridines, to broaden the prevention of cardiovascular events, the leading cause of global morbidity and mortality. Invertebrate coelomocytes structurally and functionally resemble the thrombocyte-like cells of vertebrates; therefore, the coelomic fluid in which they are suspended may contain agents controlling their clumping abilities. However, whether coelomocytes-free coelomic fluid may also affect human platelet activities was not a subject of any study. This study aimed to screen the in vitro antiplatelet and anticoagulant activities of the polysaccharide-protein complex from Dendrobaena veneta coelomic fluid (25-100 µg/mL) (PPC-DV). All tested fluid concentrations induced significant (42.4-52.5%) inhibition of adenosine-5'-diphosphate (ADP)-induced aggregation of human platelets at a level comparable to that of 140 µmol/L acetylsalicylic acid. Its relevant antiplatelet effect (27.2-45.9%) was also evidenced in the thrombin receptor-activating peptide-6 (TRAP-6) assay. Moreover, 50 and 100 µg/mL of PPC-DV inhibited arachidonic acid-inducible aggregation. No coagulopathic or cytotoxic effects of PPC-DV were observed. The study indicates that PPC-DV, at a concentration of at least 50 µg/mL, exerts a favorable antiplatelet effect by targeting at least three pathways (P2Y

Many lakes worldwide, especially shallow, experience great changes due to eutrophication, manifested in severe, usually toxic water blooms, disqualifying them from recreation. In order to improve water quality, restoration programs are implemented, including numerous methods. Intense nutrient cycling resulting from detrimental role of sediments impede obtaining of clear water state. One of the restoration methods proposed in recent years was Effective Microorganisms (EM), i.e. the set of microorganisms aiming at the inhibition of harmful bacteria through competitive exclusion. This approach was introduced in shallow Konin Lake (Western Poland), suffering from severe cyanobacterial water blooms. Prior to the treatment, protective action was conducted i.e. the elimination of external nutrient loads with backwater from the river. Changes in water chemistry, phytoplankton structure and macrophytes distribution were noted during the 5-year studies (2011–2015), covering the treatment (2013–2015) as well as two previous years. Oscillatoriacean cyanobacteria were most abundant in (2011−2012), while Nostocales in summer 2014–2015, as a result of decreased phosphorus but increased nitrogen concentrations. Slight increase in Cladoceran zooplankton was observed, but none in submerged macrophytes due to low water transparency. EM application initiated positive changes in the ecosystem by means of excessive organic matter decomposition and increased diversity of phytoplankton, nevertheless cyanobacteria blooms were still present due to high nutrient content.

Air pollution can adversely affect the immune response and increase the severity of the viral disease. The present study aimed to explore the relationship between symptomatology, clinical course, and inflammation markers of adult patients with coronavirus disease 2019 (COVID-19) hospitalized in Poland (n = 4432) and air pollution levels, i.e., mean 24 h and max 24 h level of benzo(a)pyrene (B(a)P) and particulate matter10 μm (PM

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

Swarzędzkie Lake, directly polluted for many years with municipal wastewater and heavily loaded with nutrient compounds from the catchment area, has become degraded and strongly eutrophicated. Strong cyanobacterial blooms have contributed, among others, to the cessation of recreational use of this urban lake. Its sustainable restoration was started in autumn 2011. These treatments were a combination of three complementary methods: aeration with a pulverizing aerator, phosphorus inactivation with small doses of magnesium chloride and iron sulphate (&lt, 15 kg ha&minus, 1) and biomanipulation. These treatments were carried out for three years (2012&ndash, 2014), and in the next two (2015&ndash, 2016), treatments were limited from three to one method&mdash, aeration. The obtained effects (a decrease in the number of cyanobacteria in phytoplankton and at the same time an increase in its biodiversity, decrease in chlorophylla concentration and improvement of transparency) were lost due to the cessation of phosphorus inactivation and biomanipulation. The biological balance was upset, which resulted in an increase in chlorophylla concentration, the return of cyanobacteria dominance in the phytoplankton and a deterioration of water quality. Leaving only a pulverizing aerator active, to maintain low oxygen concentrations near the bottom zone was not sufficient to ensure a gradual improvement of water quality with quite a significant external load of nutrients.

Accelerated eutrophication and requirements of the Water Framework Directive impose searching for effective restoration methods Recently positive effects are achieved by means of sustainable restoration methods that are cheap because they are limited to activities initiating natural changes in the ecosystem. Despite previous research, there is still not enough accurate data on ecosystem response (i.e. changes in the physico-chemical variables and phytoplankton composition in shallow lakes) to the sustainable restoration based on simultaneous application of several methods The restoration of shallow urban hypertrophic Swarzedzkie Lake started in autumn 2011. Three methods: were applied: (i) aeration of waters above the bottom sediments using a wind-driven aerator, (ii) phosphorus inactivation in water column using small doses of iron sulphate and magnesium chloride and (iii) biomanipulation with cyprinids catching and pike fry stocking. The aim of the study was to analyse the phytoplankton succession as well as physico-chemical variables of water quality in a shallow urban lake as a response to restoration measures. Samples were taken monthly from 2012 to 2014 at the deepest place of the lake, every 1m in the depth profile. Due to the restoration process, the Secchi depth increased to 1.00m. The oxygenation improved, as the anaerobic period in the deep water layer shortened to one month. The concentration of nutrients slightly decreased (mainly total nitrogen, from 5.5 to 4.0 mg N l −1 ), especially above the bottom. These changes had an impact on phytoplankton, which decreased twofold. The dominating cyanobacteria was eliminated or reduced and an increase in the number of chlorophytes, chrysophytes and cryptophytes has been observed. Nevertheless, the observed changes were not stable yet, so the restoration process should be continued to achieve permanent improvement.

Cyanobacterial blooms and cyanotoxins occur in freshwater lakes and reservoirs all over the world. Bacterial degradation of microcystins (MC), hepatotoxins produced by several cyanobacterial species, has also been broadly documented. However, information regarding MC biodegradation in European water bodies is very limited. In this paper, the occurrence and identification of MC biodegradation products was documented for 21 European lakes and reservoirs, many of which have well-documented cyanobacterial bloom histories. Varying cyanobacterial abundance and taxonomical composition were documented and MC producers were found in all the analysed samples. Planktothrix agardhii was the most common cyanobacterial species and it formed mass occurrences in four lakes. MC biodegradation was observed in 86% of the samples (18 out of 21), and four products of dmMC-LR decomposition were detected by HPLC and LC-MS methods. The two main products were cyclic dmMC-LR with modifications in the Arg-Asp-Leu region; additionally one product was recognized as the tetrapeptide Adda-Glu-Mdha-Ala. The composition of the detected products suggested a new biochemical pathway of MC degradation. The results confirmed the hypothesis that microcystin biodegradation is a common phenomenon in central European waters and that it may occur by a mechanism which is different from the one previously reported. Such a finding implies the necessity to develop a more accurate methodology for screening bacteria with MC biodegradation ability. Furthermore, it warrants new basic and applied studies on the characterization and utilization of new MC-degrading strains and biodegradation pathways.

Swarzedzkie Lake (near Poznan) has been heavily polluted. To improve the water quality, the restoration of lake by three methods: aeration, phosphorus inactivation using small doses of iron sulphate and magnesium chloride (FeSO 4 and MgCl 2 ) and biomanipulation was initiated at the end of 2011. The aim of the present study was to determine whether sustainable restoration has a significant impact on phytoplankton, especially cyanobacterial blooms in a shallow, urban, degraded lake. Therefore, phytoplankton and the physico-chemical parameters of water at the summer thermal stratification and autumn water mixing before (2011) and during restoration (2012–2014) was studied. Samples were collected at the deepest place of the lake in depth profile, every 1 m. Phytoplankton samples were preserved with Lugol's solution. The phytoplankton was counted using a Sedgewick-Rafter chamber with a volume of 0.46 ml. Measurements of water temperature were made in the field with a YSI multiparameter meter, transparency – using a Secchi disk. Concentrations of nitrogen, phosphorus and chlorophyll a were analysed in the laboratory according to Polish standards. As a result of restoration the water quality of the lake has improved. Cyanobacteria had almost disappeared during the first year of restoration, however, a short bloom was observed (dominated by Pseudanabeana limnetica ) in the second year. The main reason for this reappearance was a higher water temperature stimulating cyanobacteria growth, but an increased supply of phosphorus from the bottom sediments also contributed. A decrease in the temperature in the third year of restoration limited the growth of cyanobacteria again. Although the decrease in the phosphorus concentration as a result of restoration proved to be sufficient for average climatic conditions, it is highly likely to be more intense in the case of increased water temperature caused by global warming.

We report the reappearance of the rare charophyte Nitella translucens in Poland. It was identified in the soft-water lobelian Lake Jelen (North Poland) during 2013 and 2018 phytolittoral surveys. This species is considered critically endangered in various European countries and was previously classified as extinct in Poland. Its occurrence was confirmed using morphological and molecular data (ITS1-18S, ITS2-28S, rDNA, and rbcL). The N. translucens occupied ~20% of the lake bottom, at depths of 1.5-6.5 m, water pH 7.5-8.6, conductivity of 59-66 μS · cm-1 , and total nitrogen and phosphorus during growing season in the range of 1.1-1.4 mg · L-1 and 0.07-0.1 mg · L-1 , respectively. It co-occurred mainly with plant species typical for lobelia lakes: Isoetes lacustris, Littorella uniflora, and Myriophyllum alterniflorum, as well as Ceratophyllum demersum and Elodea canadensis, which are characteristic for eutrophicated waters. It appears that N. translucens may thrive in lobelia lakes during their transformation to more eutrophic states.

In this chapter we present our research on hypertrophic lakes and the identified changes in their water quality, phytoplankton and zooplankton, under the influence of restoration activities. Most of these lakes have been used for recreation, and – as a result of the deterioration of water quality – this option has lost. The average annual concentration of total phosphorus in almost all the lakes was higher than 100 μg/L, and the mean concentration of chlorophyll a was in the range of 40–172 μg/L, thus exceeding the limits for hypertrophy. To improve the water quality, so-called sustainable restoration was initiated, combining physical, chemical, and biological methods. Currently, we are documenting changes in the lakes Maltanskie, Uzarzewskie, Swarzedzkie, Rusalka, and Konin to verify the results of in-lake treatment. In the first four lakes, restored by phosphorus inactivation, oxygenation of water overlying the sediments, biomanipulation, and nitrate treatment of the hypolimnion, a gradual improvement of water quality was observed. This was manifested in phytoplankton community structure changes (less Cyanobacteria) as well as reduction in nutrient concentrations. In the case of Lake Konin, the inefficiency of EMs in lake restoration was noted.

Restoration of urban lakes becomes necessary to slow down unfavourable processes and to recover theirrecreational role. Macrophyte communities are good bioindicators, thus they can be used to assess the effectiveness of restoration. The aim of the study was to determine the dynamics and patternof macrophyte recovery as a result of the restoration measures in a degraded shallow urban lake characterized by strong cyanobacterial blooms. Annual changes in the composition and areal coverage of littoral macrophyte phytocoenoses, and in the Ecological State Macrophyte Indexwere recorded using a GPS and the ArcGIS programme and analysed in relation to changes in water quality for three years following restoration measures (phosphorus inactivation, aeration, and biomanipulation). The shifts were statistically significant in the first two for total nitrogenconcentrationand three years for chlorophyll aconcentration, whereas total phosphorus concentration only decreased significantly in the third year. Changes in water transparency were not significant. The ecological status of the lakewas good or moderate. A characteristic pattern of recovery was observed. Phytocenotic richness increased (from 9 to 12 communities) and total phytolittoral area decreased (from 42 to 37 ha, i.e. 12%) during restoration efforts. The area of hypereutrophic plant communities ( Ceratophylletumdemersi , Hydrocharitetummorsus-ranae , Typhetumangustifoliae ) decreased, the former submerged community returned ( Potametumlucentis ) and the area of some existing communities (e.g. nympheids) increased. Slow return of elodeidswas caused by low transparency andlack of submerged vegetation propagules, which are the most probable limiting factors of the recolonization process.

Long-term cyanobacterial blooms and hypereutrophic state have been typical for the shallow, urban Swarzedzkie Lake for many years. Diversion of sewage did not change its trophic status, so restoration began in autumn 2011 using the sustainable approach based on three methods. The aim of the study was to analyse how sustainable restoration affects zooplankton. We hypothesised that bottom-up and top-down methods reconstructed zooplankton composition. Thus, the abundance of large-size cladocerans increased and controlled phytoplankton effectively. The elimination of cyanobacteria bloom, the decrease of rotifer abundance and the twofold increase of filter-feeder effectiveness were observed in summer 2012. However, high phosphorus concentration, lack of regular cyprinid removal and insufficient fish stocking together with high temperature prevented zooplankton from controlling cyanobacteria bloom in summer 2013. Rotifer domination with high trophy species was noted, as before restoration. The number of rotifers decreased in 2014, while crustaceans increased due to the significant decrease of nutrient concentrations and an intensification of biomanipulation treatments. Therefore, summer phytoplankton growth was low, without cyanobacteria dominance. The rebuilding of zooplankton in Swarzedzkie Lake was observed during sustainable restoration. However, the treatments should be intensified when adverse changes were observed to obtain better results for the improvement of water quality.

Cyanobacterial blooms are an increasing threat worldwide. Invasions of certain cyanobacterial species, mainly towards higher latitudes, add to this concern as they enrich the pool of potential bloom-formers in the invaded region. Among the numerous causes of this escalating process, climate warming is commonly considered the most crucial factor, but empirical studies of this issue are lacking. The aim of our study was to identify physical, chemical and biological factors related to the occurrence of an invasive cyanobacterium at the northern border of its putative current range, and thus enabling its expansion. This study focuses on the relatively little studied species Sphaerospermopsis aphanizomenoides (Nostocales, Cyanobacteria; synonyms: Aphanizomenon aphanizomenoides, Anabaena aphanizomenoides), which is predicted to become one of the main nuisance species of the future. Forty-nine freshwater lakes located between latitudes 51° and 55°N were examined for the presence of S. aphanizomenoides, and environmental factors that could drive its occurrence were studied simultaneously. To identify factors correlated with the presence of the species, principal component analysis (PCA) and Mann-Whitney U test were performed. Water temperature did not differentiate lakes with or without S. aphanizomenoides, however the study was conducted in a particularly hot summer. Total phosphorus concentration was identified as the primary driving factor of the occurrence of S. aphanizomenoides. The species grew in poor light conditions and high phytoplankton biomass, mainly in shallow lakes. As shown by detrended correspondence analysis (DCA), the species accompanied shade tolerant, eutrophic species of native and invasive cyanobacteria as well as eukaryotic algae. Our results indicate that eutrophication may be the primary factor enabling the increasing occurrence of S. aphanizomenoides in temperate environments, and suggest that this process may stimulate expansion of cyanobacterial species towards high latitudes.

Lake Swarzędzkie, near Poznań, was a hypertrophic lake because of its high nutrient content, cyanobacteria blooms, and disruptive recreational use, especially swimming, which was popular there. This is why protection measures have been in place since 1991, and a restoration program has been ongoing since fall 2011. The evaluation of the presence and distribution of macrophytes as an important element of lake ecosystem was conducted in August 2012. Nine plant communities were observed: Phragmitetum communis; Typhetum angustifoliae; Nupharo-Nymphaeetum albae; Hydrocharitetum morsus-ranae; Thelypteridi-Phragmitetum; Cicuto-Caricetum pseudocyperi; Acoretum calami; Ceratophylletum demersi; Potametum lucentis. The first three were dominating associations. The presence of submerged vegetation appears to verify the positive impact of the applied conservation and restoration measures. Improvement is confirmed by the significant decrease in concentrations of chlorophyll-a and total nitrogen, as well as the gradual decrease in total suspended solids and increased transparency.

Strong human impact accelerates eutrophication which deteriorates water quality and consequently prevents recreational use. Increasing trophy and low transparency induce macrophyte rebuilding. A gradual transformation of the land use of the direct catchment area of Raczyńskie Lake from agricultural to recreational has been observed over the last 45 years. In built-up areas sewage facilities were inadequate and septic tanks did not work properly and as a consequence most wastewater was able to infiltrate through the ground into the lake. The lake ecosystem became unstable and water blooms intensified. The aim of the study was to assess the changes in the composition of the lake vegetation over the last 45 years, during which the use of the direct catchment has changed and recreational pressure increased. A reduction of the number of plant communities from 24 to 15 and the disappearance of almost all the submerged vegetation was observed. The dominant reed beds (Phragmitetum communis,Typhetum angustifoliae) were unable to provide a sufficient barrier to the flow of pollution from the catchment because of the numerous gaps made for angling piers, bathing sites, jetties, etc. The macrophyte index indicated a bad ecological status. To improve the ecological status of Raczyńskie Lake it is necessary to introduce intensive protection and restoration treatments.

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.

The urban Swarzędzkie Lake, into which sewage had been diverted many years ago, was still characterised by low ecological status. Three restoration methods were used in order to improve the water quality,i.e.aeration of the waters overlying the bottom sediments, inactivation of phosphorus in the water column with iron sulphate and magnesium chloride and biomanipulation with pike stocking. The aim of the research was to define seasonal and spatial changes of phosphorus internal loading from bottom sediments and to compare this with previous years. We also considered changes in the process of P release when the restoration treatments were limited after 3 yr from 3 methods to 1 method. The highest phosphorus release from bottom sediments was found in the profundal zone, where in summer periods it would reach up to 29.2 mgP m−2 day−1. The lowest P release was observed in the littoral zone, down to a depth of 3 m, where it did not exceed 10.0 mgP m−2 day−1. 31% of the whole load of P released from the bottom sediments was originated from this zone. The research showed an increase of phosphorus release in the first years of restoration treatment and a systematic decrease at all stations in the following years.

Abnormal uterine bleeding is important clinical problem in women at peri- and postmenopausal age. It may be caused by the lesions located in endometrium or in deeper uterine wall layers. An aim of this paper was a comparison of transvaginal sonography (TVS) vs. sonohysterography (SIS) in the diagnostics of endometrial polyps, endometrial hyperplasia as well as uterine myomas. Also the results of the sonographic imaging were compared to those of pathologic examination of the specimens taken from the uterine cavity. The material consisted of 100 women aged 40-80 with an irregular menstruation. All of the patients were examined gynecologically, and then the transvaginal sonography, sonohysterography and the curettage of the uterine cavity were performed. Sensitivity of TVS was 43% in endometrial polyps, 77% in endometrial hyperplasia and 69% in uterine myomas imaging. Introduction of SIS increased the sensitivity to 94%, 82%, and 95%, respectively. Specificity was similar in both techniques except endometrial hyperplasia (TVS--68%, SIS--91%). Diagnostic accuracy also improved with the SIS use reaching 93% for polyps, 89% for hyperplasia and 98% for myomas imaging. Our results show higher sensitivity and accuracy of SIS in the diagnostic of benign uterine lesions.