Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 84. (Budapest 1992)

Kristiansen, J. ; Padisák, J.: Silica-scaled chrysophytes (Chrysophyceae and Synurophyceae) from the Kis-Balaton Reservoir, Hungary

ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 84. Budapest, 1992 p. 7-16 Silica-scaled chrysophytes (Chrysophyceae and Synurophyceae) from the Kis-Balaton Reservoir, Hungary by J. KRISTIANSEN, Copenhagen & J. PADISÁK, Budapest KRISTIANSEN, J. & PADISÁK, J: Silica-scaled chrysophytes (Chrysophyceae and Synurophyceae) from the Kis-Balaton Reservoir, Hungary. -Annls hist.-nat Mus. natn. hung. 1992, 84: 7-16. Abstract - Eight species of silica-scaled chrysophytes were identified by electron microscopy of phytoplankton samples from the newly opened Kis-Balaton Water Protecting Reservoir, Hungary. The composition of this flora of silica-scaled chrysophytes is characteristic for eutrophic to hypertrophic localities. Most of the species are common and widely distributed, even cosmopolitan. The record of Chrysosphaerella annulata, which was recently described from Austria and has been recorded from widely separated places in the world, is interesting. This and three further species (Spiniferomonas trioralis, Synura petersenii and S. curtispina) are new to Hungary, while the others {Paraphysomonas vestita, Mallomonas acaroides, M. alpina, M. tonsurata) were recorded before mainly on the basis of light microscopy. Electron micrographs of the above species are presented in the paper. A checklist of all the previous records of scaled chrysophytes in Hungary is added as an Appendix. With 10 figures. The Hungarian flora of silica-scaled chrysophytes has so far only been known from light-microscopy (LM) investigations with the exception of an electron microscopical (EM) study of Paraphysomonas vestita (HAJDU 1975). Several species have been recorded, but most of these records are based on obsolete names (e. g. Mallomonas horrida, Synura verrucosa) which cannot be identified. Others have been identified with recognized species (e. g. Synura uvella, Mallomonas acaroides), but these identifications are questionable. Only a few LM identifications are reasonably trustworthy (e. g. Mallomonas tonsurata). A checklist of all scaled chrysophytes previously recorded in Hungary is given in the Appendix. However, it has long been established that electron microscopy of silica scales is necessary for reliable identifications. Thus it was decided to make a chrysophyte survey by means of EM of the samples from the Kis-Balaton, a newly constructed Water Protection Reservoir. The reservoir was opened in June 1985 at the mouth of the Zala River, the largest and most polluted inflow of Lake Balaton, which is the largest shallow lake in central Europe. The reservoir has a surface area of 18 km

2 and an average depth of 1.2 m. It is a highly eutrophic body of water, in which summer phytoplankton biomass can exceed 150 mg 1 (POMOGYI 1991). Many species of algae can be found in the reservoir. In 1988 the detailed floristic survey established the presence of 382 taxa of algae (VÍZKELETI 1991), most of which belong to Chlorococcales. Water blooms frequently occur mostly by heterocytic blue-green algae (Anabaena spp., Aphanizomenon spp., Cylindrospermopsis raciborskii), Microcystis spp., small unicellular centric diatoms and Crypto-