Taxonomical and Ecological investigations of freshwater Dinophyta species

The aim of the work was to characterise the Hungarian Dinophyta species at various levels as follows: development of methods for preservation and investigation, taxonomy, ecology.
Within the frames of this study we developed methods for preservation and the „examination process” of Dinophyta taxa. Plate structure analysis and morphology of an freshwater Dinophyta species established its as a new species for the science, Peridiniopsis kevei. Peridinium lomnickii Woloszynska was investigated both by light and scanning electron microscopy with special attention to the importance of development of cellulose plates during the life cycle. We suggest that the three varieties of Peridinium lomnickii, represent only different life cycle stages of the species. The present study provides the first report on the quantitative occurrence of the unknown temporary cysts and palmella life cycle stages of the common Dinophyta species Peridinium aciculiferum and two special life cycle stages microspores and nucleoid stage which was not known for freshwater Dinophyta species. The presence of microspores – "orange-brown" bodies – in high quantity, if they are propagula indeed, can result in a much higher rate of population increase than it would be possible with the "traditional" doubling. It also may explain the rapid development of Dinophyta blooms.
Peridinium palatinum belongs to a group of algal species of which we have only a few taxonomical and ecological data, although in some running and standing waters it can be found in large numbers. The aim of our study, accomplished from 1990 to 1996, was revealing the occurrence of this species. Comparing eleven types of waters in which it either appeared or not, it could be established that P. palatinum occurs in waters that exceed a relatively high level of organic matter concentration. The temperature is important in the excystment and in the development of vegetative cells. Consequently, its occurrence can well indicate relatively high concentrations of organic nutrients during the winter season in freshwaters.