Head of Department:  Lajos Vörös, DSc

The research team studies the species composition and dynamics of phytoplankton (pico-, nano- and microplankton), phytobenthos and periphyton communities. Long term phytoplankton monitoring is continued in the four basins of the lake. The components and the function of the microbial loop are studied. The light and temperature dependency of the growth and photosynthesis of the phytoplankton, phytobenthos and periphyton communities are investigated. Studies on the diversity and production of autotrophic picoplankton in shallow lakes are in progress. Measurements are conducted on the underwater light climate. The research team constructed an algal culture collection (Algal Culture Tihany=ACT) containing the most abundant and characteristic cyanobacteria (picocyanobacteria, N-fixing filamentous cyanobacteria etc.), diatoms and green algae of Lake Balaton and various strains from other shallow lakes.

The research activity of the working team is focused on the cycling of the main nutrients (carbon, nitrogen and phosphorus). The aim of investigation is to predict the effect of the change in nutrient load and water level on the water quality of Lake Balaton. The concentrations of the different phosphorus and nitrogen forms in the water column and sediment are regularly analysed. Uptake of phosphorus and nitrogen are studied using ³²P and ¹⁵N labelled compounds, both under natural conditions and in pure cultures. Experiments are conducted on the competition between the bacteria and algae for these resources. Atmospheric nitrogen fixation, ammonium regeneration and denitrification processes in the water column and sediment are investigated. The origin, physical and chemical characteristics of the dissolved organic (humic) compounds, their bioavailability and contribution to the carbon pool, transformations, degradation due to UV radiation and their ecological effects are studied.

The research team study the effect of different limiting factors on the spatial distribution of aquatic macrophytes in lake Balaton. The team looks at the effect of abiotic factors on the morphology and physiology of reed (Phragmites australis) and thus on distribution of reed stands in lake Balaton. As a part of this research we examine the genetic diversity of reed in lake Balaton and its surroundings. With the help of orthophotographs and GIS we map the dynamics of spatial distribution of reed in lake Balaton.

The other field of work of the team is the effect of major abiotic factors on the distribution of submerged macrophytes in lake Balaton. We study the effect of light and temperature on the processes of photosynthesis and respiration. Thus we can estimate the spatial distribution of plants in the lake and correlate with its real spread.