Remains of Pediastrum kawraiskyi Schmidle (Chlorophyta, Protococcales) in the sediments of Lake Balaton. A paleolimnological study

Sebestyén, Olga (1968) Remains of Pediastrum kawraiskyi Schmidle (Chlorophyta, Protococcales) in the sediments of Lake Balaton. A paleolimnological study. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 35. pp. 203-226. ISSN 0365-3005

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Abstract

In nine samples of a core from sediments of Lake Balaton which is representative in palynological view, remains were found of those Pediastrum species which inhabit our lake at present (P. simplex, P. duplex and P. boryanum). Remains both of P. biradiatum and P. tetras noted in our time as planktoxene elements carried by draining canals from adjacent marshy meadows (ancient bays of the lake) and by the river Zala were absent in the analysis of quantitative slides. In the sections, 290-123 cm depth, corresponding the age ±8000-±1000 b. p., of the 410 cm long core В 28, remains of Pediastrum kawraiskyi were found in decreasing percentage frequency. Such remains were recovered from other cores from deeper (earlier) layers. There are several data on the recent occurrence of P. k. in the literature. It occurs in both recent and subfossil conditions in one lake in the Baikal region and, only the remains were found in the sediments of Lake Balaton. All data refer to the active state of the life-cycle of this species. From the subfossil Balaton data we might conclude th a t its ecological valence is more restricted than that of the other three Pediastrum species which inhabit our lake at present. It seems that the environmental conditions, offered by our lake, could satisfy the ecological demands of P. к. only in a section of its past history: Late Pleistocene + part of the Holocene. This means, that the period when P. k. was a member of the biota of the lake marks a distinct portion in the history of Lake Balaton. From the literature we learn that P. k. is a northern form with stenotopic nature and perhaps has a demand for higher temperature for a brief period for both the development and the maintenance of the population. From the differences of the results of the analysation for cladoceran and Pediastrum remains in Pleistocene samples originated from two different cores but from the same layer - as could be established on palynological ground the conclusion might be drawn th a t the limnological situations in that part of the lake which situated south from the Tihany-peninsula were not uniform in the Late Pleistocene or at least a part of that age. This would also suggest that in the Late Pleistocene perhaps there were no connections between the water-bodies represented by the profiles Boglár-Révfülöp and Balatonifenyves -Szigliget. (Pre-Balaton condition?, Sebestyén 1968b See Lóczy 1916, p. 585, Fig. 274.) No more could be concluded from the analysis of the microfossils recovered in the course of this study and from the pertinent literature which, however, the author was not in the position to consider in its full extent. Results of the investigations of more samples both of the core В 28 and other cores of the sediments of the present Lake Balaton and the same of the "berkek", chemical analysis of the samples, and more knowledge on the ecology of P. k. (literature, culture experiments) are needed in order to approach the goal: to gain an insight into the environmental situations in a particular part of the past history of Lake Balaton.

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