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Monodominant (one species dominates) or polidominant (multiple species dominate) cyanobacterial blooms are pronounced in productive freshwater ecosystems and pose a potential threat to the biota due to the synthesis of toxins. Seasonal changes in cyanobacteria species and cyanometabolites composition were studied in two shallow temperate eutrophic lakes. Data on cyanobacteria biomass and diversity of dominant species in the lakes were combined with chemical and molecular analyses of fifteen potentially toxin-producing cyanobacteria species (248 isolates from the lakes). Anatoxin-a, saxitoxin, microcystins and other non-ribosomal peptides formed the diverse profiles in monodominant (Planktothrix agardhii) and polidominant (Aphanizomenon gracile, Limnothrix spp. and Planktolyngbya limnetica) lakes. However, the harmfulness of the blooms depended on the ability of the dominant species to synthesize cyanometabolites. It was confirmed that P. agardhii produced a greater amount and diverse range of MCs and other NRPs. In the polidominant lake, isolates of the co-dominant A. gracile, L. planctonica and P. limnetica synthesized no or only small amounts of cyanometabolites. In general, the profile of cyanometabolites was greater in cyanobacteria isolates than in environmental samples, indicating a high potential for toxic cyanobacteria bloom.

Studies on the Batorino Lake were aimed at assessing the quantitative and qualitative characteristics of the autotrophic component of bottom sediments, as well as searching for their relationships with the data of spectral analysis of the pigment composition. The content of total chlorophyll a (without correction for the presence of phaeopigments) was relatively low – 12.7 ± 10.2 µg/g wet weight of bottom sediments. The content of carotenoids averaged 10.24 ± 4.89 µg/g wet weight of bottom sediments. It has been shown that pigment indices: Е450 /Е480, Е480/Е664, Е430/Е664, Е430/Е412, characterise the structural indicators of bottom sediments and reflect the long-term trends in the development of primary producers in water ecosystems, primarily phytoplankton. During the preliminary analysis, auxiliary pigment indices for controlling the purity of the extract and the clarity of the prescribed spectrum were calculated: Е664/Е720, Е430/Е720, Е530/Е720, Е412/Е720, Е430/Е530, Е664/Е530, Е412/Е664. A close inverse relationship was revealed between Е430/Е664 index and the amount of chlorophyll a at different depths of bottom sediments (r = – 0.7), as well as an average correlation between the Е430/ Е412 index and the proportion of phaeopigments (r = – 0.56).

This study describes the first report on saxitoxins (STXs) and anatoxin-a (ANTX-a) production by cyanobacteria in Lithuanian lakes. Seasonal fluctuation patterns for neurotoxins were determined in samples collected from eutrophic lakes during July–September. Strains of Aphanizomenon gracile, A. flos-aquae, Cuspidothrix issatschenkoi, Sphaerospermopsis aphanizomenoides and Anabaenopsis cf. elenkinii were also isolated from the lakes and screened for the occurrence of neurotoxic STXs, ANTX-a and for the cytotoxin cylindrospermopsin (CYN). The highest concentration of STX (up to 1.06 µg l–1 in Lake Jieznas) was detected during July‒August and coincided with a predominance of A. gracile in the phytoplankton. Of the isolated strains, only A. gracile was confirmed to be a producer of STXs by chemical (LC-MS/MS) and genetic (sxtA) methods. Sequencing of the phycocyanin intergenic spacer and flanking regions (cpcBA) revealed that A. gracile formed a genetically homogenous group. Only trace amounts of ANTX-a were detected in field samples (up to 0.31 µg l–1 in Lake Širvys). CYN was detected in neither the bloom samples nor in the isolated strains.

Freshwater macroalgae produces a wide range of bioactive compounds, and interest in utilizing its biomass is growing rapidly. Meanwhile, exploiting renewable sources for biomass collection could lead to more sustainable biotechnological chains. The aim of this study was to investigate Cladophora glomerata biomass from Lithuanian rivers as a potential raw material for biotechnology. For this reason, phenolic compound profiles, antioxidant activity and pigment concentrations were determined in macroalgal biomass samples collected from the following four Lithuanian rivers: Dubysa (B1), Šventoji (B2), Nevėžis (B3) and Jūra (B4). The highest total phenolic compound content was determined in B3 (1.32 mg GAE/g). Three phenolic acids were identified, namely gallic (12.94–35.13 µg/g), p-hydroxybenzoic (23.97–29.05 µg/g) and p-coumaric (1.79–6.46 µg/g). The results indicate significant C. glomerata antioxidant activity; the highest reducing power reached 0.737 AU (B3), the total antioxidant content was 1.47 mg Trolox/g (B3), DPPH and ABTS radical scavenging was 11.09% (B3) and 97.86% (B1) and FRAP activity 20.86 µmol/L (B3). The content of pigments ranged from 0.56-0.74, 0.39–0.57, 0.17–0.23 to 0.11–0.17 mg/g in chlorophyll a, b, carotenoids, and lutein, respectively. To conclude, C. glomerata macroalgal biomass may have the potential to act as a functional raw material, as several groups of bioactive compounds and antioxidant activities were observed.

‘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.

In this study, we examined how land use and urbanization changes in adjacent areas affected biological productivity and carbon cycling in a lake ecosystem over 100 years and how these changes are reflected in carbon isotope variations. We performed radiocarbon (14C) activity and stable carbon isotope ratio analysis in two organic fractions: humin and humic acids of lake sediment. Additionally, we performed pigment and diatom analysis and determined the carbonate and organic matter (OM) content in sediments. Over the last century, the estimated 14C reservoir age in both sediment organic fractions varied from 1136 ± 112 yr to 5733 ± 122 yr. The increase in the reservoir age by 1175 ± 111 yr was related with higher inputs of pre-aged organic carbon and 14C depleted hard water due to the opening of the channel connecting two lakes. Nuclear weapons tests caused an increase in the reservoir age of up to 5421 ± 135 yr and 5733 ± 122 yr in humin and humic acids, respectively. 13C values in the humic acid fraction showed a tendency to decrease, depending on the content of autochthonous versus allochthonous OM in sediments, while changes in the sources of OM had a minor impact on the stable carbon isotope composition in the humin fraction.

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

Global warming and eutrophication contribute to formation of HABs and distribution of alien cyanobacteria northward. The current study assessed how alien to Europe Sphaerospermopsis aphanizomenoides and Chrysosporum bergii will co-occur with dominant native Planktothrix agardhii and Aphanizomenon gracile species under changing conditions in temperate freshwaters. The experiments were carried out to examine the effect of nutrients and temperature on the growth rate of cyanobacteria, production of cyanotoxins, and interspecies competition. The highest growth rate was determined for A. gracile (0.43 day&minus, 1) and S. aphanizomenoides (0.40 day&minus, 1) strains at all the tested nutrient concentrations (IP and IN were significant factors). S. aphanizomenoides adapted to the wide range of nutrient concentrations and temperature due to high species ecological plasticity, however, A. gracile was able to suppress its dominance under changing conditions. Regularity between tested variables and STX concentration in A. gracile was not found, but IP concentration negatively correlated with the amount of dmMC-RR and other non-ribosomal peptides (NRPs) in P. agardhii strains. The relative concentration of NRPs in nontoxic P. agardhii strain was up to 3-fold higher than in MC-producing strain. Our study indicated that nutrients, temperature, and species had significant effects on interspecies competition. A. gracile had a negative effect on biomass of both alien species and P. agardhii.

The collection of pure cultures of algae and cyanobacteria deposited at the Nature Research Centre is a unique and diverse culture collection in Lithuania. It was initiated on the basis of a few national projects in 2010 as an outcome of ecological and molecular studies on invasive and harmful bloom-forming algae and cyanobacteria. To date, the collection holds more than 500 strains, which belong to ten classes, over 70 genera and 140 species. Strains were isolated from Lithuanian freshwaters and the Curonian Lagoon. The collection serves for various research topics including species interactions, molecular analysis, biotechnology (remediation of wastewaters, cell wall disruption, high- and low-value bioproducts), as well as for teaching purposes., Gamtos tyrimų centro dumblių ir melsvabakterių kolekcijoje palaikoma didelė iš Lietuvos gėlų vandens telkinių ir Kuršių marių izoliuotų rūšių įvairovė. Kolekcija įkurta 2010 m., vykdant invazinių ir potencialiai toksinių, vandens „žydėjimus“ sukeliančių dumblių ir melsvabakterių ekologijos ir genetinius tyrimus Lietuvos mokslo tarybos finansuojamų projektų laikotarpiu. Šiuo metu kolekcijoje yra daugiau nei 500 kamienų, priklausančių 10 klasių, apie 70 genčių ir 140 rūšių. Algologiškai gryni kamienai naudojami moksliniams eksperimentiniams tyrimams ir edukaciniams tikslams. Gamtos tyrimų centro tyrėjų grupė, vykdanti algologinius tyrimus, toliau aktyviai plėtoja biotechnologinius taikomojo pobūdžio darbus, susijusius su nuotekų vandenvala, ląstelių sienelių ardymo technologijomis, vykdo komerciškai vertingų bioproduktų paiešką.

Increasing human activity has resulted in the transformation of waters and their landscape leading to fragmentation and degradation of natural ecosystems. We hypothesized that adjacent surrounding structures of water reservoir is weighty factor explaining changes in phytoplankton. The aim of the study was to find what level of identification is adequate to routine analyses and assess the best criteria that reflect structure of adjacent surrounding of reservoirs. Lithuanian and Polish reservoirs located in similar climatic conditions and of similar morphology were studied. The adjacent land use was described based on Corine Land Cover 2006. The physico-chemical parameters of waters, structure and biomass of phytoplankton, Shannon index and obligatory autotrophic to mixotrophic species ratio were analyzed. The main difference between reservoirs was natural (Lithuanian reservoir: 67.8%) and agricultural landscape structure (Polish reservoir: 78.4%). Both ecosystems showed significant statistical differences in a few chemical features and in phytoplankton taxonomic and morphologically based functional groups (MBFG), Shannon index and autotrophic to mixotrophic species ratio. The dominant phytoplankton groups and MBFG better reflected stresses resulted differences of adjacent surrounding structure, compared with single species. In conclusion, the best criteria indicated the differences in the structure of adjacent surrounding of water ecosystems are MBFG and autotrophic to mixotrophic species ratio were presented.

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.

In response to global warming, an increase in cyanobacterial blooms is expected. In this work, the response of two native species of Planktothrix agardhii and Aphanizomenon gracile, as well as the response of two species alien to Europe&mdash, Chrysosporum bergii and Sphaerospermopsis aphanizomenoides&mdash, to gradual temperature increase was tested. The northernmost point of alien species distribution in the European continent was recorded. The tested strains of native species were favoured at 20&ndash, 28 &deg, C. Alien species acted differently along temperature gradient and their growth rate was higher than native species. Temperature range of optimal growth rate for S. aphanizomenoides was similar to native species, while C. bergii was favoured at 26&ndash, 30 &deg, C but sensitive at 18&ndash, 20 &deg, C. Under all tested temperatures, non-toxic strains of the native cyanobacteria species prevailed over the toxic ones. In P. agardhii, the decrease in concentration of microcystins and other oligopeptides with the increasing temperature was related to higher growth rate. However, changes in saxitoxin concentration in A. gracile under different temperatures were not detected. Accommodating climate change perspectives, the current work showed a high necessity of further studies of temperature effect on distribution and toxicity of both native and alien cyanobacterial species.

Inland waters are an important habitat for flora and fauna and are also used for aesthetic, recreational, and industrial needs; therefore, monitoring the current state of freshwaters and applying measures to improve water quality are of high importance. To have an efficient monitoring system that could cover large areas, the use of remote sensing data is crucial. In this study the suitability of the Sentinel-2 Multispectral Imager data is tested for observing cyanobacteria bloom events in the eutrophic lakes and retrieving the chlorophyll-a concentration – an indicator of phytoplankton biomass. The analysis is carried out using data from four lakes in Lithuania – two eutrophic blooming lakes and two oligo-mesotrophic non-blooming lakes. The results showed that reflectances are higher in the eutrophic lakes than in the oligo-mesotrophic lakes due to the presence of an optically active constituent, namely, chlorophyll-a pigment. We tested empirical equations for chlorophyll-a concentration retrieval in eutrophic lakes derived in other studies to check whether they could be used without adaptation to local conditions. Most of the equations performed well (R2 = 0.5–0.8); however, they had high RMSEs = 17–53 μg L–1. The equation used with the bottom of atmosphere data CHL8_L2A (R2 = 0.76) had the lowest RMSE = 9 μg L–1. In addition, we derived empirical equations for eutrophic lakes in Lithuania. The equations that were based on the Sentinel-2 band ratio B5/B4 and the three band (B4, B5, and B8A) expression performed the best (R2 = 0.77–0.79) and had lower RMSE = 7 μg L–1 than empirical equations from other studies. A larger in situ dataset could improve the algorithm performance in retrieving the chlorophyll-a concentration. The first attempts to map water quality parameters in eutrophic lakes in Lithuania using the data received from the Sentinel-2 MSI sensor show good results, as the changes in reflectance, caused by the changes in chlorophyll-a concentration, can be seen from satellite images.

The current study summarised the diversity of cyanobacteria found in various habitats of the second largest raised bog of Lithuania. A total of 56 cyanobacteria species that comprise 19% of all phycoflora diversity in Kamanos raised bog were recorded. Species from the Chroococcales (32 species) order and the Chroococcus (7), Aphanothece (7) genera were the most numerous. Twenty one cyanobacteria species were found in Lithuania for the first time. Most of species recorded in Kamanos raised bog were cosmopolite or distributed in temperate zone. One third of the species were characteristic particularly of the peat bogs. Thirty nine species of cyanobacteria were specific to the particular water body and occurred only in 1–3 of the studied localities. Only five species, i.e. Chroococcus turgidus, Aphanocapsa grevillei, Aphanothece elabens, Cyanosarcina sp. and Hapalosiphon sp. were common. Peculiarities of the habitat were the most important drivers determining species richness and composition of cyanobacteria in a particular locality.

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.

This article discusses the recent ecological status of Lake Drūksiai, the former cooler of the INPP, based on phytoplankton assessment in 2011. The data of integrated long-term investigation of phytoplankton over a period of 31 years from the construction of the INPP till decommissioning are also provided. The operation of the INPP obviously influenced the phytoplankton community by stimulating temporal and spatial instability of the algal succession.Pagal 2011 metais atliktų planktono tyrimų rezultatus įvertinta ir aptariama dabartinė Drūksių ežero ekologinė būklė. Analizuojami ir 31 metų trukmės tyrimų duomenys, surinkti nuo Ignalinos atominės elektrinės statybos pradžios iki jos uždarymo. Elektrinės darbas neabejotinai paveikė fitoplanktono bendriją ir jos sukcesijos stabilumą.

Invasions in aquatic ecosystems can have negative ecological and economic effects. It is important to identify the impacts of non-native species in order to evaluate the outcomes of invasion processes and implement measures of management. A biopollution assessment method (BPL, or biopollution level index) was applied to measure the impact of Gonyostomum semen (Raphidophyceae) on the lakes of Lithuania. It occurred in humic, lobelia and eutrophic lakes. G. semen , comprising abundance up to 1.05 × 10 6 cells L −1 and biomass up to 24.8 mg L −1 , was assigned as an invasive species that caused recognisable changes on phytoplankton communities, habitats and ecosystem functioning. The dominance of G. semen shifted phytoplankton composition from the prevailing small chrysophytes and green algae to the raphidophyte and large dinophytes being dominant. The assessment for the lakes revealed the highest biopollution level (BPL = 3, strong impact) for the lakes in the northern part, and moderate biopollution (BPL = 2, moderate impact) for the other regions of Lithuania.

The nuisance large flagellate Gonyostomum semen (Raphidophyceae) is typical for brown-water lakes in temperate and boreal regions. This study is focused on two annual cycles of G. semen in shallow temperate lakes (one of which stratifies) with a particular emphasis on the species’ ecology and its potential impact on the alternation of phytoplankton assemblages. Temperature and phosphorus were the main forces driving seasonal growth of the raphidophyte. G. semen occurred at a broad temperature range and prevailed for the extended period from spring to late autumn at maximum biovolume and forming up to 98.7% of total phytoplankton in June–July and/or September. The species exclusively dominated under phosphate-replete conditions and caused heavy blooms in the stratified lake. The species outcompeted other flagellates in the lakes; considerable fluctuations in phytoplankton species composition occurred during the periods at low G. semen biovolume.

Karosienė J., Kasperovičienė J., 2012: Peculiarities of epiphyton algal communities formation on different macrophyte species [Skirtingų makrofitų rūšių epifitono dumblių bendrijų formavimosi ypatumai]. - Bot. Lith., 18(2): 154-163. The epiphyton on different aquatic vegetation represented by emerged macrophytes (Phragmites australis, Equisetum fluviatile, Schoenoplectus lacustris), floating-leaved plants (Nuphar luteum) and submerged macrophytes (Potamogeton perfoliatus, Chara rudis) was studied in two meso- and mesoeutrophic lakes. The morphological characteristics, physiological and synecological peculiarities of plant host had more effect on epiphyton algae abundance and biomass than species richness. The highest densities of algae were associated with helophytes Phragmites australis, Equisetum fluviatile, the lowest was recorded on Schoenoplectus lacustris and laminae of Nuphar luteum. Loosely attached diatoms prevailed on helophytes, adnate species on Nuphar luteum laminae. Cyanobacteria and green algae were more abundant on Nuphar luteum laminae and Potamogeton perfoliatus.

Industry, transport and unsustainable agriculture result in the increased quantity of wastewater, release of nutrients and emission of carbon dioxide that promotes eutrophication of water bodies and global climate change. the application of microalgae for phycoremediation, their biomass use for human needs may increase sustainability and have a positive effect on the regional development. The experiments were carried out in order to establish the feasibility of treating the local municipal wastewater with microalgae consortia and their biomass potential for biofuel production. The results revealed that Chlorella/Scenedesmus consortium eliminated up to 99.7–99.9% of inorganic phosphorus and up to 88.6–96.4% of inorganic nitrogen from the wastewater within three weeks. The ammonium removal was more efficient than that of nitrate. Chlorella algae grew better in diluted, while Scenedesmus – in the concentrated wastewater. The consortium treated wastewater more efficiently than a single species. The maximum biomass (3.04 g/L) of algal consortium was estimated in concentrated wastewater. Algae accumulated 0.65–1.37 g of CO2/L per day in their biomass. Tus, Chlorella/Scenedesmus consortium is a promising tool for nutrients elimination from the local wastewater under the climatic conditions specific to Lithuania. However, none of the two species were able to accumulate lipids under the nitrogen starvation conditions.