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B-Beres V.,Environmental Protection and Nature Conservation Authority | Torok P.,Mta Of Biodiversity And Ecosystem Services Research Group | Kokai Z.,Environmental Protection and Nature Conservation Authority | Krasznai E.T.,Environmental Protection and Nature Conservation Authority | And 2 more authors.
Hydrobiologia | Year: 2014

Classification of taxa into ecological guilds is based on the relation of respective taxa to nutrient enrichment and their resistance to physical disturbance. We hypothesized that ecological guild's proportion and their taxa composition were strongly effected both by extremely changing water regime and nutrient contents. Diatom composition, guild dynamics and the diatom-based ecological status assessment index were studied in the Sebes-Körös River (South-East Hungary) in a year with extremely changing water regimes. There were highly pronounced changes in species composition during the whole vegetation period including the formation of running and standing water segments in autumn. While the proportions of ecological guilds showed no significant correlations with the studied environmental parameters, they were more balanced in high water discharge period than in the low water discharge period. Taxa compositions of segments were mainly determined by the preferences and strategies of a respective species and/or genera, regardless to their guild affiliation. These results point out that ecological guild characterisation should be refined using ecological knowledge at the subgenus level. We suggest to establish several subdivisions within the guilds to consider the differences in life strategies (CSR model) and life forms, and to implement the accumulated knowledge of nutrient preferences/indication of a respective taxa. © 2014 Springer International Publishing Switzerland. Source


B-Beres V.,Environmental Protection and Nature Conservation Authority | Bacsi I.,Debrecen University | T-Krasznai E.,Environmental Protection and Nature Conservation Authority | Kokai Z.,Environmental Protection and Nature Conservation Authority | Buczko K.,Hungarian Natural History Museum
Acta Botanica Croatica | Year: 2015

In Hungary Navicula jakovljevicii was firstly recorded in biofilm of Elodea nuttallii in 2005 in an oxbow of the catchment area of the River Danube. Subsequently, in 2006, N. jakovljevicii was also found in the same oxbow on reed stems as well. In the following years it appeared in another oxbow, suggesting an expanding distribution in the tributaries of the Danube in Hungary. The Hungarian population can be characterised as having mixed morphological features in comparison with other known N. jakovljevicii populations of Europe. When the morphological study was expanded, a similar, but 'giant form' was detect ed in fossil material. We found similarities and a possible connection between N. jakovljevicii and Navicula lucida, a diatom taxon described from a Neogene deposit in the Carpathian Basin. Despite the morphological similarities in the shape, apices, striae pattern and raphe structure of these two species, there are significant differences in valve dimensions: the valves of N. lucida are larger and more heavily silicified than N. jakovljevicii. Source


Kokai Z.,Environmental Protection and Nature Conservation Authority | Bacsi I.,Debrecen University | Torok P.,Mta Of Biodiversity And Ecosystem Services Research Group | Buczko K.,Hungarian Natural History Museum | And 4 more authors.
Acta Botanica Croatica | Year: 2015

The occurrence and spread of halophilic diatom taxa in freshwater lotic ecosystems are influenced both by natural processes and anthropogenic pollution. Diatom assemblages were regularly monitored in lowland lotic systems in Hungary (Central Europe) during the unusually dry year of 2012. Highly pronounced changes in diatom composition were observed from spring to autumn. Halophilic taxa (especially Nitzschia sensu lato species) appeared in the dry autumn. In addition, the total relative abundances of halophilic species also increased up to autumn. Abundance of Nitzschia cf. lorenziana and Nitzschia tryblionella showed a positive correlation with chloride and phosphate concentration, while that of other taxa like Tryblionella apiculata or Tryblionella calida showed a positive correlation with the concentration of nitrate. Our findings clearly demonstrated that these halophilic and mesohalophilic diatom taxa were sensitive indicators of even short-term changes in lowland lotic ecosystems, such as the increasing salt concentration from spring to autumn caused by the lack of rainfall and/or environmental loads. Source


Novak Z.,Debrecen University | Janoszky M.,Environmental Protection and Nature Conservation Authority | B-Beres V.,Environmental Protection and Nature Conservation Authority | Nagy S.A.,Debrecen University | Bacsi I.,Debrecen University
Bulletin of Environmental Contamination and Toxicology | Year: 2014

Effects of zinc on growth, cell morphology, oxidative stress, and zinc removal ability of the common phytoplankton species Desmodesmus communis were investigated at a concentration range of 0.25-160 mg L-1 zinc. Cell densities and chlorophyll content decreased in treated cultures, changes in coenobia morphology and elevated lipid peroxidation levels appeared above 2.5 mg L-1 zinc. The most effective zinc removal was observed at 5 mg L-1 zinc concentration, while maximal amount of removed zinc appeared in 15 mg L-1 zinc treated culture. Removed zinc is mainly bound on the cell surface. Dead biomass adsorbed more zinc than living biomass relative to unit of dry mass, but living biomass was more effective, relative to initial zinc content. This study comprehensively examines the zinc tolerance and removal ability of D. communis and demonstrates, in comparison with published literature, that these characteristics of different isolates of the same species can vary within a wide range. © Springer Science+Business Media New York 2014. Source


Bacsi I.,Debrecen University | Novak Z.,Debrecen University | Janoszky M.,Environmental Protection and Nature Conservation Authority | B-Beres V.,Environmental Protection and Nature Conservation Authority | And 2 more authors.
International Journal of Environmental Science and Technology | Year: 2015

Effects of zinc on growth, cell morphology, oxidative stress responses and zinc removal activity of two common phytoplankton species, Monoraphidium pusillum (Printz) Komárková-Legnerová and Monoraphidium griffithii (Berkeley) Komárková-Legnerová were investigated at a concentration range of 0.2–160 mg l−1 zinc. Cell densities and chlorophyll content decreased compared with controls in cultures of both species, effective concentrations causing 50 % growth inhibition within 72 h on the basis of cell numbers were 33.69 and 25.63 mg l−1 zinc for M. pusillum and M. griffithii, respectively. Changes in cell morphology and elevated lipid peroxidation levels appeared in zinc-treated cultures of both species, but only at higher (>10 mg l−1) zinc concentrations. The most effective zinc removal appeared at 20 and 10 mg l−1 zinc concentration for M. pusillum and M. griffithii, respectively. Removed zinc is mainly bound on the cell surface in the case of both species. This study provides new data for the zinc tolerance and zinc removal ability of the green algae M. pusillum and M. griffithii and shows that green algal species common in surface waters could have zinc tolerance and zinc-binding abilities, which makes them feasible in treatment of waters contaminated with 10–20 mg l−1 zinc. © 2014, Islamic Azad University (IAU). Source

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