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Research Description
Selected Publications
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Our research were and are aimed at the application of biomanipulation as a new ecological tool for improvement in water quality of shallow waters in Hungary. The biomanipulation or the manipulation of fish communities means biological interference into the food web to get improved water quality. The in situ and pond experiments pointed to the applicability of the biomanipulation technique in Hungarian shallow water ecosystems following a reduction of external nutrient load to a technologically possible minimal level.

The majority of the Hungarian waters are shallow with a mean depth typically 1-3m. Fifty- hundred years ago most of our lakes were clear with many submerged macrophytes. They had considerable stocks of predatory fish and rich in flora-fauna as well as much plant eating birds and diving ducks. Due to increased nutrient supply most natural water have shifted to a turbid state with phytoplankton blooms. Cyprinids such as breams and roach dominate fish communities. However, with changing biological structures we can see opportunities to control the water quality of our natural waters parallel with decreasing the external nutrient supply.

Experiments under controlled conditions have proved that the older age classes of cyprinids resuspend sufficient amount of suspended and particulate particles along with the absorbed nutrients from the sediments to the overlying water as a result of bioturbation. Consequently benthivorous fish behaviour may significantly influence the nutrient budget of the ecosystems they inhabit at high stocking rate (>100 kg/ha). Since both the direct and indirect effects of cyprinids proved to be stock dependent, it was necessary to search for the “optimal” fish stock of the given age-class structure in the larger scale experiments at which natural standing waters give the best water quality. It become clear from our simulated pond experiments of wide range of fish stock (0-500kg/ha) that at the minimising or if possible exclusion of the external nutrient loading the biomass ratio of cyprinid potential preyfish (breams, roach and carp) and predators (pike-perch and pike) of 60:40% gave the best results as regards the water quality parameters. With the predatory fish stocking we were able to reverse eutrophication processes in the system with cyprinid fish biomass not higher than 100kg/ha. The conclusion that the fish manipulation may be an efficient management tool in the near future in relation to improving water quality of shallow water ecosystems seems to be realistic.

Tátrai, I. (1995): Food chain manipulation as a tool in management of shallow lakes. Case study: Lake Balaton, pp. 163-171. In: R. De Bernardi & G. Giussani (Eds.) Guidelines of Lake Management, Vol. 7., Biomanipulation in Lakes and Reservoirs Management. ILEC/UNEP, Kusatsu, Shiga, Japan.

Tátrai, I., Oláh, J., Józsa, V., Kawiecka, B.J., Mátyás, K., Paulovits, G., (1997a). Biomass dependent interactions in pond experiments: responses of lower trophic levels to fish manipulations. Hydrobiologia 345, 117-129.

Tátrai, I., Oláh, Paulovits, Mátyás, K G ., Kawiecka, B.J., Pekár, F.(1997b). Changes in the lower trophic levels as a consequence of the level of fish manipulation in the ponds. Int. Rev. ges. Hydrobiol., 82, 213-224.

Tátrai, I., Paulovits, G., Mátyás, K., Korponai, J. and Pomogyi, P. (1998). Long-term food web interactions in Kis-Balaton reservoir. Int. Rev. ges. Hydrobiol., 83, 515-522.

Tátrai, I., Mátyás, K., Korponai, J. Paulovits, G., Pomogyi, P. and Présing, M. (1999). Stable isotope analysis of food webs in wetland areas of Lake Balaton, Hungary. Arch. Hydrobiol. 146, 117-128.

Tátrai, I., Mátyás, K., Korponai, J. Paulovits, G., Pomogyi, P.(2000). The role of Kis-Balaton Water protection system in the control of water quality of Lake Balaton. Ecological Engineering 16: 73-78.

Tátrai, I. and Istvánovics,V. (1986). The role of fish in the regulation of nutrient cycling in Lake Balaton. Freshwater Biol., 16, 417-424.

Tátrai, I. (1987). The role of fish and benthos in the nitrogen budget of Lake Balaton. Arch. Hydrobiol., 110, 291-302.

Tátrai, I. and de Bernardi, R. (1992). Indirect impact of cyprinid fish fry on the growth and fecundity of Daphnia obtusa. Arch. Hydrobiol.,125:371-381.

Breukelaar, E..,Lammens, E.H.R.R., Klein Breteler, J.G.P. and Tátrai, I.(1994a). Effects o benthivorous bream (Abramis brama L.) and carp on sediment resuspension and the concentra tions of nutrients and chlorophyll-a. Freshwater Biol., 32, 113-121. 

LIST OF PUBLICATIONS

Dr. Jan Kubecka- Hydrobiological Research Institute, Ceske Budejovice, Czech Republic in application of hydroacoustic survey in studying distribution of fish communities in Lake Balaton.

Dr. Josef Wanzenböck, Limnological Institute, Mondsee, Austria, in sampling fish fry in lakes using tow nets 

Dr. Soren Berg, Institute for Fisheries Research, Silkeborg, Denmark, Studying the fish activities and feeding behaviour using radio telemetry

OTKA- T-06363, 2.4 MFt/yr, 1993-1996, Fish biomanipulation in pond ecosystems, co-ordinator 

OTKA- T 0 22991, 1.6 MFt/yr, 1997-98, Fish biomanipulation in pond ecosystems, co-ordinator 

OTKA-T 029099, 2.2 MFt/yr, 1999-2002, Manipulation of the fish communities in the Kis-Balaton Water Protection Reservoir I. 

OVIBER Kft, NYUDUVIZIG, 1.3 MFt/yr 1995-2001, Feeding relationships of fish and transfer of matter in the open water areas of Kis-Balaton Water Protection Reservoir, co-ordinator 

Prime Minister Office, 4.2 MFt/yr, 1995-1999, Management of fish communities of Lake Balaton: predator-prey relationships in the littoral region, co-ordinator 

Prime Minister Office, 3.6 MFt/yr, 2000-2002: Stocks of the introduced fish communities in Lake Balaton, co-ordinator

1997, University of Helsinki, Lammi Biological Station

1998, Limnological Institute, Mondsee, Austria

1999, Hydrobiological Research Institute, Ceske Budejovice, Czech Republic

2000, Institute for Fisheries Research, Silkeborg, Denmark