G. Varbiro

G. Varbiro
Hungarian Academy of Sciences | HAS · Danube Research Institute



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I am an ecologist- hydrobiologist at the Hungarian Centre for Ecology. My research interests focus on ecosystem ecology, aquatic macroinvertebrates and ecological assessment.
Additional affiliations
January 2011 - October 2014
Hungarian Academy of Sciences
  • Researcher


Projects (10)
Archived project
The term potamoplanton collects algae occurring in river plankton, independently of possible origins like autochthonous growth in the river flow, drifted from the phytobenthos, or originated from connected laterals. While compositional changes of other river biotas in relation to environmental gradients are well known, longitudinal patterns of potamoplankton have been less frequently studied. For this reason, the potamoplankton of the relatively unregulated River Loire is presented in this Dissertation at the whole river scale from years 2009 to 2011. Research as well as monitoring programs of river potamoplankton use species or genus level data, which are often difficult to interpret. Contrary, modelling studies often simplify potamoplankton to major algal classes, which might be insufficient to cover the functional complexity required for an ecology-based implementation of river processes. As an alternative method, the grouping of algae into functional groups―’FGs’ may hold the potential for new approaches in potamoplankton ecology and in river water quality management. Compositional change of FGs is expected to follow longitudinal processes in rivers, and also better indicate ecological status than other systems based on taxa composition or species richness. In order to prove the reliability of FGs in rivers, their compositional changes are related to natural gradients like geography, as well as to physical and chemical anthropogenic pressures, occurring along the Loire.
Archived project
Long-term changes in phytoplankton (microscopic algae living in suspension) have been addressed in marine and lake ecosystems, but rarely in rivers. Large rivers, however, are highly human-impacted, where global warming may constrain further ecosystem functioning at a long-term scale. The middle section of the Danube River is an excellent large river example for long-term human and global warming impacts. Similar to other large European rivers, the Danube was among the most eutrophic (polluted) ones in the 70s and 80s, which trend has been reversed due to enhanced efficiency in wastewater management, but also to other human impacts like damming. A long-term decrease in phytoplankton quantity (i.e. Chlorophyll-a, biomass) and taxonomic richness (how many species occur in the Danube) has formerly been observed. However, the functional community composition (i.e. what those species can do) that relates to ecosystem functioning directly (how the system works) has not been addressed previously. Here, we analysed a 34-year long dataset from the middle river section at Göd (N-Budapest), Hungary. We focused on 1) gradual changes in environmental conditions, and functional composition and diversity of phytoplankton; 2) how global warming and human impacts affected the cell size (body size) of phytoplankton since reduced body size is among the universal ecological responses to global warming.
Archived project
The major aim of our project is to better understand environmental constraint shaping the rheoplankton functional composition in the rivers of the Carpathian Basin, Hungary). We are mainly interested in the functional group composition (FG) of river phytoplankton sensu Reynolds (Reynolds et al. 2002; Borics et al. 2007; Padisák et al. 2009) and characterization of niche space of FGs sensu Reynolds using the OMI approach (for details see; Doledec et al. 2000). We intend to answer the role of FGs niche charateristics (i.e breadth and position) may play in the regional occupancy of phytoplankton FGs. Further plans related to the project are under development phase. Preliminary results; a, we could identify habitat template characteristics of each riverine phytoplankton functional group; and therefore we provide niche characteristics (i.e niche position and breadth) for the occurrence of functional groups under specific set of environmental conditions. b, all the identified FGs could be merged in six functional niche groups. c, we demonstrated that niche characteristics may play important role in the regional occupancy of riverine phytoplankton FGs, and these are related weakly to each other! d,We showed, that niche breadth and niche position of rheoplankton (i.e. notion proposed for phytoplankton taxa of rvers in rivers) FGs have similar importance in the regional distribution of FGs . e,we concluded that niche space breadth and position role in the regional occupancy .distribution can be separated as they were weakly related to each other. for details see our published article here and https://academic.oup.com/plankt/article/42/3/355/5837349 now already with open access Some ideas about our future plans , aims and concepts . We aim to answer whether niche characteristics of FGs differ significantly among different river typology classes of Hungarian lowland rivers. Furthermore, we want to answer whether niche characteristics of FGs show considerable changes along the longitudinal sections of Hungarian large rivers (i.e.River Danube, River Tisza drainage area). And so on...... We hope that ; Our final project results can be expanded later to further watersheds of the rivers or watersheds from Europe ,and even to other temperate zones of the Continents. and that characterization of niche space of phytoplankton taxa or FGs can expand our ability to understand what environmental factor can be considered essential for occurrence, regional distribution and even ( reccuring and non-reccuring) successional dynamics of phytoplankton taxa or FGs in the rivers. Project content modified by Nagy-László Zsolt on 16.november.2021