Phytoplankton produces the majority of organic matter in most of the aquatic ecosystems. This group represents the first level of the pelagic food chain not only in the oceans and inland standing waters, but also in the middle and lower sections of large rivers. Despite its crucial role, much less information is available about the ecology of phytoplankton in riverine ecosystems. Our group investigates the compositional and biomass changes of riverine phytoplankton, and their relationship with the major drivers.

• Nagy-László Z, J Padisák, G Borics, A Abonyi, V B-Béres, G. Várbíró 2020. Analysis of niche characteristics of phytoplankton functional groups in fluvial ecosystems. Journal of Plankton Research 42 (3), 355-367
• Abonyi, A., KT Kiss, A Hidas, G Borics, G Várbíró, E Acs 2019. Cell Size Decrease and Altered Size Structure of Phytoplankton Constrain Ecosystem Functioning in the Middle Danube River Over Multiple Decades. Ecosystems, 1-11
• Várbíró, G., Padisák, J., Nagy-László, Z., Abonyi, A., Stanković, I., Udovič …G.Borics. 2018. How length of light exposure shapes the development of riverine algal biomass in temperate rivers? Hydrobiologia 809 (1), 53-63
• Abonyi A, É Ács, A Hidas, I Grigorszky, G Várbíró, G Borics, KT Kiss. 2018. Functional diversity of phytoplankton highlights long‐term gradual regime shift in the middle section of the Danube River due to global warming, human impacts and oligotrophication. Freshwater Biology 63 (5), 456-472
• Wang C, V B-Béres, Cs Stenger-Kovács, X Li, A Abonyi. 2018. Enhanced ecological indication based on combined planktic and benthic functional approaches in large river phytoplankton ecology. Hydrobiologia 818: 163-175.
• Ágnes Bolgovics, Gábor Várbíró, Éva Ács, Zsuzsa Trábert, Keve Tihamér ..G. Borics. 2017. Phytoplankton of rhithral rivers: its origin, diversity and possible use for quality-assessment. Ecological Indicators 81, 587-596
• Nagy-László Z, G Várbíró, A Abonyi, J Padisák, G Borics. 2016. A planktonikus növényi biomassza és a trofitás változása a Tisza hazai szakaszán és mellékfolyóiban= Longitudinal changes of phytoplankton quantity and trophic status along the Tisza River HIDROLÓGIAI KÖZLÖNY 96 (Klsz.), 64-69
• Bolgovics Á, É Ács, G Várbíró, KT Kiss, G Borics. 2016. Mely tényezők határozzák meg a Sajó fitoplanktonjának kovaalga összetételét?= What factors determine the diatom compositon of the Sajó river? HIDROLÓGIAI KÖZLÖNY 96 (ksz.), 22-25
• Bolgovics Á, É Ács, G Várbíró, KT Kiss, BA Lukács, G Borics, 2015. Diatom composition of the rheoplankton in a rhithral river system.  Acta Botanica Croatica 74 (2), 303-316
• Abonyi A, M Leitão, I Stanković, G Borics, G Várbíró, J Padisák. 2014. A large river (River Loire, France) survey to compare phytoplankton functional approaches: do they display river zones in similar ways? Ecological Indicators 46, 11-22.
• Stanković I, T Vlahović, MG Udovič, G Várbíró, G Borics. 2012. Phytoplankton functional and morpho-functional approach in large floodplain rivers. Phytoplankton responses to human impacts at different scales, Hydrobiologia. 217-231

Water quality assessment has been considered as one of the oldest and most widespread practical application of aquatic ecology. It covers a wide range of topics related to sampling problems, spatial and temporal heterogeneity of ecosystems, water body typology, metric selection and development, stressor/metric relationships, metric uncertainty, etc.  Adoption of the EU Water Framework Directive triggered hundreds of researches in this field in the last two decades across Europe. Our group focuses on the implementation of the WFD in Hungary, and is doing researches in order to satisfy the needs of stakeholders involved in water quality management.

• Zs Kókai, G Borics, I Bácsi, Á Lukács, B Tóthmérész, E Csépes, P Török, V B-Béres. 2019. Water usage and seasonality as primary drivers of benthic diatom assemblages in a lowland reservoir. Ecological Indicators 106: 105443.
• Carvalho, L, EB Mackay, AC Cardoso, A Baattrup-Pedersen, S Birk, …G. Boics…. 2019. Protecting and restoring Europe's waters: an analysis of the future development needs of the Water Framework Directive. Science of the Total Environment 658, 1228-1238
• Borics G, G Wolfram, G Chiriac, D Belkinova, K Donabaum. 2018. Intercalibration of the national classifications of ecological status for Eastern Continental lakes Publications Office of the European Union
• Bolgovics Á, É Ács, G Várbíró, J Görgényi, K Tihamér Kiss, A Földi, …G. Borics. 2017. Benthic diatom-based lake types in Hungary. Fundamental and Applied Limnology/Archiv für Hydrobiologie 189 (2), 105-116
• Borics, G, E Acs, E Boros, T Er, I Grigorszky, KT Kiss 2016. Water bodies in Hungary—an overview of their management and present state. Hung J Hydrol 96, 57-67.
• Borics G, A Abonyi, G Várbíró, J Padisák, E T-Krasznai. 2015. Lake stratification in the Carpathian basin and its interesting biological consequences. Inland Waters 5 (2), 173-186
• Borics G, BA Lukács, I Grigorszky, Z László-Nagy, Á Bolgovics, S Szabó, …G. Várbíró. 2014. Phytoplankton-based shallow lake types in the Carpathian basin: steps towards a bottom-up typology. Fundamental and Applied Limnology/Archiv für Hydrobiologie 184 (1), 23-34
• M Kelly, É Ács, V Bertrin, H Bennion, G Borics, A Burgess, L Denys, …2014. Water Framework Directive Intercalibration Technical Report: Lake Phytobenthos ecological assessment methods. Publications Office of the European Union
• Carvalho L, C McDonald, C de Hoyos, U Mischke, G Phillips, G Borics, …2013.  Sustaining recreational quality of European lakes: minimizing the health risks from algal blooms through phosphorus control Journal of Applied Ecology 50 (2), 315-323
• Carvalho, S Poikane, AL Solheim, G Phillips, G Borics, J Catalan, …2013. Strength and uncertainty of phytoplankton metrics for assessing eutrophication impacts in lakes. 2013. L Hydrobiologia 704 (1), 127-140
• Borics G, L Nagy, S Miron, I Grigorszky, Z László-Nagy, BA Lukács, G. Várbíró.  2013. Which factors affect phytoplankton biomass in shallow eutrophic lakes? Hydrobiologia 714 (1), 93-104
• Borics,G.,  G Várbíró, J Padisák. 2013. Disturbance and stress: different meanings in ecological dynamics? Hydrobiologia 711 (1), 1-7.
• Várbíró G, G Borics, B Csányi, G Fehér, I Grigorszky, KT Kiss, A Tóth, …2012. Improvement of the ecological water qualification system of rivers based on the first results of the Hungarian phytobenthos surveillance monitoring. Hydrobiologia 695 (1), 125-135
• Borics G, A Abonyi, E Krasznai, G Várbíró, I Grigorszky, S Szabó, C Deák, …2011. Small-scale patchiness of the phytoplankton in a lentic oxbow.  Journal of Plankton Research 33 (6), 973-981.

Composition and diversity of algal assemblages reflects spatial and temporal heterogeneity of the environment and complexity of biotic interactions. Theoretical and methodological improvements in ecology helped to understand the main drivers of diversity in the recent decades, and application of large databases, together with new statistical tools provided opportunities to study phytoplankton diversity at large spatial and productivity scales. Researches of our group focuses on various aspects of phytoplankton (species and functional) diversity, including definitions and measures, mechanisms maintaining diversity, and its dependence on productivity, or habitat size. Recently, functional approaches have been developed for benthic algae, especially for benthic diatoms. These approaches provide new perspectives for assessing the environment-benthic algae’ relationships in freshwater ecosystems. Our group has been involved in the development of these new tools.

Selected publications:

• Á Bolgovics, B Viktória, G Várbíró, EÁ Krasznai-K, É Ács, KT Kiss, … G Borics. 2019. Groups of small lakes maintain larger microalgal diversity than large ones. Science of the Total Environment 678, 162-172
• Görgényi, J., B Tóthmérész, G Várbíró, A Abonyi, T Enikő, B Viktoria, …G.Borics. 2019. Contribution of phytoplankton functional groups to the diversity of a eutrophic oxbow lake. Hydrobiologia 830 (1), 287-301
• RMW Muhl, DL Roelke, T Zohary, M Moustaka‐Gouni, U Sommer … G. Borics. …… 2018. Resisting annihilation: relationships between functional trait dissimilarity, assemblage competitive power and allelopathy. Ecology letters 21 (9), 1390-1400
• Á Lukács, Zs Kókai, P Török, I Bácsi, G Borics, G Várbíró, E T-Krasznai, B Tóthmérész, V B-Béres. 2018. Colonisation processes in benthic algal communities are well reflected by functional groups. Hydrobiologia 823: 231-245.
• Várbíró G, J Görgényi, B Tóthmérész, J Padisák, É Hajnal, G Borics 2017. Functional redundancy modifies species–area relationship for freshwater phytoplankton. Ecology and evolution 7 (23), 9905-9913
• Bolgovics Á, É Ács, G Várbíró, J Görgényi, G Borics. 2016. Species area relationship (SAR) for benthic diatoms: a study on aquatic islands. Hydrobiologia 764 (1), 91-102
• Borics G, B Tóthmérész, G Várbíró, I Grigorszky, A Czébely, J Görgényi, 2016. Functional phytoplankton distribution in hypertrophic systems across water body size. Hydrobiologia 764 (1), 81-90
• Görgényi J, G Várbíró, A Abonyi, B Tóthmérész, G Borics, 2016. A fitoplankton funkcionális csoportjainak hatása a fajtelítődési görbék alakjára egy eutróf állóvíz esetén= Effect of phytoplankton functional group on the shape of the species accumulation curves. HIDROLÓGIAI KÖZLÖNY 96 (Ksz.), 32-36
• P Török, E Krasznai, V Bácsiné Béres, I Bácsi, G Borics, B Tóthmérész 2016. Functional diversity supports the biomass-diversity humped-back relationship in phytoplankton assemblages. Functional Ecology 30 (9), 1593-1602.
• B-Béres, V, Á Lukács, P Török, Zs Kókai, Z Novák, E T-Krasznai, B Tóthmérész, I Bácsi. 2016. Combined eco-morphological functional groups are reliable indicators of colonisation processes of benthic diatom assemblages in a lowland stream. Ecological Indicators 64: 31–38.
• B-Béres, V. I Bácsi, E T-Krasznai, Zs Kókai, K Buczkó. 2015. First report of Navicula jakovljevicii Hustedt (Bacillariophyta) from Hungary: distribution, comparative morphology and a related species. Acta Botanica Croatica 74: 253-264.
• Borics, G. J Görgényi, I Grigorszky, Z László-Nagy, B Tóthmérész, …G.Várbíró. 2014. The role of phytoplankton diversity metrics in shallow lake and river quality assessment. Ecological indicators 45, 28-36
• Görgényi J, Á Bolgovics, G Borics. 2013 Miként befolyásolja az élőhely mérete a fitoplankton aktuális diverzitását? HIDROLÓGIAI KÖZLÖNY 93 (5-6), 30-32
• Bolgovics, Á., G Borics, J Görgényi. 2013. A tóméret és a fajszám közötti összefüggés bentikus és planktonikus algák esetén? HIDROLÓGIAI KÖZLÖNY 93 (5-6),
• Borics, G., B Tóthmérész, BA Lukács, G Várbíró. 2012. Functional groups of phytoplankton shaping diversity of shallow lake ecosystems. Phytoplankton responses to human impacts at different scales, Hydrobiologia. 251-262

One of the most challenging topics in ecology is studying how climate change impacts and modifies community composition. Without this knowledge, no effective biomonitoring programs, cost-effective environmental protection and biodiversity conservation strategies could be planned and accomplished. In the Carpathian Basin, climate change led to changes in water regime of watercourses inducing flash floods in rivers and streams or even drying up of ponds and formerly permanent small watercourses. However, only few data are available how drought induced changes influence freshwater ecosystems and the ecological status of waters. Thus, researchers in our group focus on the impacts of these extreme events on the water regime of water currents, and on structure, composition and diversity of benthic algal communities.

• Várbíró G, G Borics, MH Novais, MM Morais, F Rimet, A Bouchez, K Tapolczai, I Bácsi, P Usseglio-Polatera, V B-Béres. 2020. Environmental filtering and limiting similarity as main forces driving diatom community structure in Mediterranean and continental temporary and perennial streams. Science of the Total Environment accepted.
• Ács É, A Földi, CF Vad, Z Trábert, KT Kiss, M Duleba, G Borics. 2019. Trait-based community assembly of epiphytic diatoms in saline astatic ponds: a test of the stress-dominance hypothesis. Scientific reports 9 (1), 1-11
• B-Béres V, B Tóthmérész, I Bácsi, G Borics, A Abonyi, K Tapolczai, F Rimet, A Bouchez, G Várbíró, P Török. 2019. Autumn drought drives functional diversity of benthic diatom assemblages of continental streams. Advances in Water Resources 126: 129-136.
• Lukács Á, Zs Kókai, P Török, I Bácsi, G Borics, G Várbíró, E T-Krasznai, B Tóthmérész, V B-Béres. 2018. Colonisation processes in benthic algal communities are well reflected by functional groups. Hydrobiologia 823: 231-245.
• B-Béres V, Á Lukács, P Török, Zs Kókai, Z Novák, E T-Krasznai, B Tóthmérész, I Bácsi. 2016. Combined eco-morphological functional groups are reliable indicators of colonisation processes of benthic diatom assemblages in a lowland stream. Ecological Indicators 64: 31–38.
• Kókai Zs, I Bácsi, P Török, K Buczkó, E T-Krasznai, Cs Balogh, B Tóthmérész, V B-Béres. 2015. Halophilic diatom taxa are sensitively indicating even the short term changes in lowland lotic systems. Acta Botanica Croatica 74: 287–302.
• B-Béres V, P Török, Zs Kókai, E T-Krasznai, B Tóthmérész, I Bácsi. 2014. Ecological diatom guilds are useful but not enough sensitive indicators of extremely changing water regimes: is it necessary to establish guild subdivisions? Hydrobiologia 738: 191–204

Biovolume is one of the most important characteristics of planktic organisms which basically influences their functional properties like sinking velocity or tolerance to grazing. Biovolume calculation of microalgae is based on the determination of the geometrical shapes that approximate best the shape of the algal cells. After measuring the necessary dimensions of the cells and using the formulas for the geometric shapes cell biovolumes can be calculated. However, this approach may have uncertainties in the case of complicated forms.  Our group is working on a novel approach, which uses 3D models to visualise algae, and calculates the volume and the surface of these virtual models. On the bases of these models, specific shape and surface area constants can be calculated. These species-specific constants can be stored in a database, and enable a quick and accurate surface area and volume computation even for the most complicated algal forms. Precise estimation of these metrics could help in the calculation of size-related metrics and traits like surface area/volume ratio or diameter of spherical equivalent, which allows more accurate data analysis and interpretation of results in phytoplankton ecology.

The littoral zones of freshwater lakes are considered as buffer zones, which protect the aquatic ecosystem from the perturbations arriving from the shoreline. However, the littoral not simply buffers the undesirable impacts, but actively takes place in shaping the phytoplankton diversity of the open water, since it serves as a source of various algal groups. Metaphytic algae i.e. algae living among the macrophytes, comprise divers assemblages both in terms of their phylogeny and functional properties. Our previous studies suggest that a specific source-sink dynamics should exists between the metaphytic algal assemblages of the littoral zone and the phytoplankton of the pelagial. Details of this process have not been addressed previously, therefore within this research we aim to give a comprehensive overview of this topic by accomplishing field investigations, pond-enclosure and laboratory experiments. The expected results will contribute to the deeper understanding of phytoplankton diversity and also be conducive to the effective management of lake ecosystems.

• Borics, G., Abonyi,A.,  Salmaso N., & Ptacnik R. Freshwater phytoplankton diversity: models, drivers and implications for ecosystem properties Hydrobiologia

Laboratory experiments imitating field circumstances provide appropriate tools for studying interactive relations between alga-alga and alga-toxic cyanobacteria or even alga-non-toxic cyanobacteria cultures under well-controlled conditions. Our research group in strong cooperation to Debrecen University focuses on taxon and/or trait-dependent competition and allelopathy in algal assemblages.

• Dobronoki D, V B-Béres, G Vasas, S Gonda, SA Nagy, I Bácsi. 2019. Potential role of the cellular matrix of Aphanizomenon strains in the effects of cylindrospermopsin—an experimental study. Journal of Applied Phycology 31: 1805–1817.
• B-Béres V, G Vasas, D Dobronoki, S Gonda, SA Nagy, I Bácsi. 2015. Effects of cylindrospermopsin producing cyanobacterium and its crude extracts on a benthic green alga – competition or allelopathy? Marine Drugs 13: 6703-6722.
• B-Béres V, I Grigorszky, G Vasas, G Borics, G Várbíró, SA Nagy, Gy Borbély, I Bácsi. 2012. The effects of Microcystis aeruginosa (cyanobacterium) on Cryptomonas ovata (Cryptophyta) in laboratory cultures: why these organisms do not coexist in steady-state assemblages? Hydrobiologia 691: 97-107.

Planktiviorous fish play crucial role in controlling autotrophic potential of the pelagial. Artificial introduction of the non-native filter-feeder Asian carp (Hypophthalmichthys spp.) in Hungarian waterbodies resulted in controversial effects on the quality of waters. Stocking of this fish frequently eliminated zooplanktonic filter feeders and initiated a trophic cascading response, which ended in huge waterblooms. Within this research, we studied the planktic components in the alimentary track of the Asian carp, and survival success of algae, which enables their dispersion.

• Görgényi J, G Boros, Z Vitál, A Mozsár, G Várbíró, G Vasas, G Borics. 2016.The role of filter-feeding Asian carps in algal dispersion. Hydrobiologia 764 (1), 115-126.
• Mozsár A, A Specziár, I Battonyai, G Borics, J Görgényi, H Horváth, …2017. Influence of environmental factors and individual traits on the diet of non-native hybrid bigheaded carp (Hypophthalmichthys molitrix× H. nobilis) in Lake Balaton, Hungary. Hydrobiologia 794 (1), 317-332
• Battonyai I, A Specziár, Z Vitál, A Mozsár, J Görgényi, G Borics, LG Tóth, …2015. Relationship between gill raker morphology and feeding habits of hybrid bigheaded carps (Hypophthalmichthys spp.). Knowledge and Management of Aquatic Ecosystems, 36
• Vitál Z, A Specziár, A Mozsár, P Takács, G Borics, J Görgényi, L G-Tóth,  2015. Applicability of gill raker filtrates and foregut contents in the diet assessment of filter-feeding Asian carps. Fundamental and Applied Limnology/Archiv für Hydrobiologie 187 (1), 79-86.

Other research activities of the group include issues on toxic algal blooms, algal taxonomy, and other themes within limnology

• Novák Z, S Harangi, E Baranyai, S Gonda, V B-Béres, I Bácsi. 2020. Effects of metal quantity and quality to the removal of zinc and copper by two common green microalgae (Chlorophyceae) species. Phycologial Research 12422.
• Szabó S, ETHM Peeters, G Borics, S Veres, PT Nagy, BA Lukács, 2020. The ecophysiological response of two invasive submerged plants to light and nitrogen, Frontiers in plant science 10, 1747
• Figler A, V B-Béres, D Dobronoki, K Márton, SA Nagy, I Bácsi. 2019. Salt tolerance and desalination abilities of nine common green algae isolates. Water 11: 2527.
• Szabó S, E Peeters, G Várbíró, G Borics, BA Lukács 2019. Phenotypic plasticity as a clue for invasion success of the submerged aquatic plant Elodea nuttallii. Plant Biology 21 (1), 54-63
• Riba M, A Kiss-Szikszai, S Gonda, G Boros, Z Vitál, AK Borsodi, G Krett, .Borics, G.    ..2019. Microcystis chemotype diversity in the alimentary tract of bigheaded carp. Toxins 11 (5), 288
• Trábert Z, K Buczkó, G Borics, MG Udovic, B Karthick, L Ector, A Földi, …2019. Biogeography and morphology of a poorly known diatom Dorofeyukea rostellata (Hustedt) Kulikovskiy & Kociolek. Limnetica 38 (2), 743-758.
• Grigorszky I, KT Kiss, LJ Szabó, G Dévai, SA Nagy, I Somlyai, C Berta, ..G.Borics….. 2019. Drivers of the Ceratium hirundinella and Microcystis aeruginosa coexistence in a drinking water reservoir. Limnetica 38 (1), 41-53
• Bácsi, I.,  J Deli, S Gonda, I Mészáros, G Veréb, D Dobronoki, SA Nagy, V B-Béres, G Vasas. 2018. Non-steroidal anti-inflammatory drugs initiate morphological changes but inhibit carotenoid accumulation in Haematococcus pluvialis. Algal Research 31C: 1-13.
• Schmera D, D Árva, P Boda, E Bódis, Á Bolgovics, G Borics, A Csercsa, …2018. Does isolation influence the relative role of environmental and dispersal‐related processes in stream networks? An empirical test of the network position hypothesis usinmultiple taxa. Freshwater Biology 63 (1), 74-85
• Krasznai-K EÁ, P Boda, G Borics, BA Lukács, G Várbíró. 2018. Dynamics in the effects of the species–area relationship versus local environmental factors in bomb crater ponds. Hydrobiologia 823 (1), 27-38
• Bácsi, I., V B-Béres, Zs Kókai, S Gonda, Z Novák, SA Nagy, G Vasas. 2016. Effects of non-steroidal anti-inflammatory drugs on cyanobacteria and algae in laboratory strains and in natural algal assemblages. Environmental Pollution 212: 508-518.
• Padisák J, G Vasas, G Borics, 2016. Phycogeography of freshwater phytoplankton: traditional knowledge and new molecular tools. Hydrobiologia 764 (1), 3-27
• Bácsi, I.,  Z Novák, M Jánószky, V B-Béres, I Grigorszky, SA Nagy. 2015. The sensitivity of two Monoraphidium species to zinc – their possible future role in bioremediation. International Journal of Environmental Science and Technology 12: 2455-2466.
• Bácsi, I., S Gonda, V B-Béres, Z Novák, SA Nagy, G Vasas. 2015. Alterations of phytoplankton assemblages treated with chlorinated hydrocarbons: effects of dominant species sensitivity and initial diversity. Ecotoxicology 24: 823–834.
• Lukács BA, B Tóthmérész, G Borics, G Várbíró, P Juhász, B Kiss, Z Müller, 2015.  Macrophyte diversity of lakes in the Pannon Ecoregion (Hungary).  Limnologica 53, 74-83
• Bácsi, I., T Török, V B-Béres, P Török, B Tóthmérész, SA Nagy, G Vasas. 2013. Effects of chlorinated hydrocarbons on a laboratory cyanobacterium strain (Synechococcus PCC 6301) and on natural assemblages of phytoplankton enclosed in microcosms. Hydrobiologia 710: 189–203.
• Schindler S, M Kropik, K Euller, SW Bunting, C Schulz-Zunkel, A Hermann, …G. Borics…2013. Floodplain management in temperate regions: is multifunctionality enhancing biodiversity? Environmental Evidence 2 (1), 10
• Vasas G, O Farkas, G Borics, T Felföldi, G Sramkó, G Batta, I Bácsi, …2013. Appearance of Planktothrix rubescens bloom with [D-Asp3, Mdha7] MC–RR in gravel pit pond of a shallow lake-dominated area. Toxins 5 (12), 2434-2455.
• Viktoria B, I Grigorszky, G Vasas, G Borics, G Várbíró, SA Nagy, G Borbély,  2012. The effects of Microcystis aeruginosa (cyanobacterium) on Cryptomonas ovata (Cryptophyta) in laboratory cultures: why these organisms do not coexist in steady-state assemblages? Hydrobiologia 691 (1), 97-107
• Vasas G, M Márta, G Borics, S Gonda, C Máthé, K Jámbrik, ZL Nagy 2012. Occurrence of toxic Prymnesium parvum blooms with high protease activity is related to fish mortality in Hungarian ponds. Harmful algae 17, 102-110
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