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.

Our focus is on the relationship between environmental pollution and health problems according to the following major points:

1. Screening-level risk assessment of pollutants (SLRA), with special reference to heavy metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls. The use and drawing up proper site models to identify pollution sources, pathways and fate of contaminants of potential concern.

2. Toxic effect assessment of pollutants of both human and „natural” origin (like toxins produced by cyanobacteria): comprising hazard identification, accumulation and dose-response studies as well as exposure assessment using both invertebrate and vertebrate aquatic model organisms as well as cell culture models.

2.1. The neuronal mechanisms are studied on different levels of neuronal integration from behavior to individual nerve cells of the neuronal networks involved in the potentially toxic effects of environmentally concerned pollutants. By combining biochemical, morphological and electrophysiological techniques the exact target of the effects are determined on cellular and membrane functions, interneuronal connections as well as on neurotransmitter levels which modulate neuronal activity.

2.2. Application of in vitro toxicological techniques on different cell lines. Follow up the influence of toxic substances (including cyanobacterial toxins as microcystine, cylindrospermopsin) on regulation of the cell cycle, chromatin condensation, cell death process, cascade reactions of the signal transduction pathways, and the structure of the cytoskeleton.

SERFŐZŐ, Zoltán	PhD, team leader	serfozo, ext#130, 202
GYŐRI, János	PhD	gyori, ext#219
FARKAS, Anna	PhD	farkas, ext#217
VEHOVSZKY, Ágnes	PhD	agnes, ext#206
BALÁZSNÉ HOLLÓSY, Eugénia	technician	geni, ext#111
ERŐSNÉ IHÁSZ, Katalin	technician	ikati, ext#217