Dr. Murai Éva - Gubányi András szerk.: Parasitologia Hungarica 29-30. (Budapest, 1997)

© Hungarian Natural History Museum Hungarian Society of Parasitologists Preliminary survey of the parasite fauna of some important fish species in the Upper-Reservoir of the Kis-Balaton System Csaba SZÉKELY and Kálmán MOLNÁR Veterinary Medical Research Institute, Hungarian Academy of Sciences, H-1143 Budapest, Hungária kr t. 21, Hungary (Received 12 January, 1997) Abstract: Parasitic infections of a total of 100 specimens of 13 fish species inhabiting the Upper-Reservoir (Hídvégi Lake) of Kis-Balaton were surveyed in the first year of a four-year project. During the survey, which involved five samplings in the season that lasted from spring to autumn, 36 parasites were identified to the species while 14 others to the genus level. The commonest parasite of Kis-Balaton is Diplostomum spathaceum s. 1. which causes infection of high prevalence but low intensity in many fish species. It is interesting that, despite the abundance of birds acting as definitive hosts, many of the helminth parasites common in Lake Balaton are absent from Kis-Balaton, probably because of the lack of intermediate hosts or due to differences in other ecological factors. Of the parasites found, 45 species are reported for the first time from Kis-Balaton. Key words: Parasites: Protozoa (Mastigophora, Apicomplexa, Myxozoa, Ciliophora), Platyhelminthes (Monogenea, Cestoda, Trematoda), Nemathelminthes (Nematoda), Annelida (Hirudinea), Mollusca (Bivalvia), Arthropoda (Crustacea), hosts: Esox lucius, Abramis brama, Alburnus alburnus, Carassius auratus gibelio, Scardinius erythrophthalmus, Blicca bjoerkna, Cyprinus carpio, Rutilus rutilus, Tinea tinea, Silurus glanis, Gymnocephalus cernuus, Perca fluviatilis, Stizostedion lucioperca, parasite fauna, Kis-Balaton Water Reservoir, Hungary INTRODUCTION The Kis-Balaton is a reconstructed wetland and water reservoir whose most important role is to protect and improve, through its filtering and storage functions, the water quality of Lake Balaton, the biggest lake of Central Europe. It is also an important nature conservation and fishing area. Due to its shallow water and partially "cassette-like" structure, this water reservoir is highly sensitive to environmental influences; therefore, factors affecting its biological balance frequently lead to fish mortality. Zoological research of the Kis-Balaton was started several years ago. That research involved a study of fish population structure in the Upper-Reservoir (Hídvégi Lake) which was flooded years ago, and fish-faunistic studies on the Lower-Reservoir (Fenéki Lake) which is still being filled