Szekessy Vilmos (szerk.): A Magyar Természettudományi Múzeum évkönyve 53. (Budapest 1961)
Halász, M.: The microvegetation of the acrothermae of Harkány
Sites III to VI, since they are not the immediate biodynamic habitats of the springs but constitute a large, open water surface, are exposed to aerial effects, but they are still free of biotic or mechanic pollution, and they do not mix with foreign waters. Biotopes I and II, being the artificial stone sinks of the two hot springs, receive the spouting thermal waters directly from the very depths of the earth. As the original thermal waters are conveyed by closed pipes from the well to the four other biotopes, it is quite impossible that pollution could occur at any of these places. In biotope VI, on the bottom of the great mud basin, there settles down a specific mud of hcaUng power, developed by chain reactions in the genuine waters of the well. In this mud, there appears a considerable amount of pure, elementar Sulphur, freed by the chain reactions. A part of the mud is made up from the sedimentation of rock granules swept up by the waters from the deep (C s a j á g h i 1956). In the hot vapour of the thermal waters above the mud, there develop specific microvegetational colonies on the wooden walls. Beside the important fact that all six collecting sites are situated in the biodynamical space of the pollution-free, clear, thermal spring waters, it is a very essential oecological factor that these six biotopes are in the open air, exposed to sunshine and fresh air the whole year round. That there could develop, both quabtatively and quantitatively, one of the richest acrothermal vegetation of the country in Harkány, one of the most decisive contributing factors, aside of the high temperature of the water and its other special chemical and physical properties, was assuredly this very oecological circumstance. According to the results of my observations in Harkány through many years, the microvegetational zones developed on both biotopes of the spouting thermal waters in strict accordance with Schwabe's rule (Schwabe 1949, p. 447). Also substantiated by my observations gained in the years of survey, the microvegetational zones form, in the biotopes evolving at the points of eruption of the hot springs of Harkány, in strict accordance with this rule. In Survey Site I, namely in the well-basin of Hot Spring I, where the temperature ranges from 42° C to 27° C — decreasing gradually in the rate of distance from the eruption of the thermal w r aters and in the overlaying zones of the biodynamical habitat — the thickness of the algal crust varies between 0,5 mm and 4 mm, differentiated into corresponding zones visible also by the naked eye. The algal cover is locally coriaceous, at other points gelatinous, or again filamentous ; its color, in subsequent zones from the bottom to the top, a deep bluish-green, ohve green, greenish-brown, reddish-brown, the uppermost layer being mainly bght greenish to yellow. In Survey Site II, that is, in the basin of the second hot spring (46° C, respectively 50° C to 27° C), the microvegetational coating is of an almost identical arrangement and consistency, with only the temperature being higher by a few degrees due to the setting of the spring being narrower than that of the first one. In Survey Sites III, IV, and V, (the three cooling basins), the temperature ranges from 54° C to 28° C. The microvegetational coating is on the inner side of the basins and also of a zonal arrangement. It is a considerable difference that the lower zones are situated under the surface of the thermal water. The depth of the algal crust ranges from 0,1 mm to 2,6 mm. The temperature of Site III is 54° C, that of the fourth from 40° C to 31° C, and 31° C-28° C in the fifth habitat. The consistency of the coating of Site III is very fine, minutely granulated. Its color is yellowish-green. On the other hand, the consistency of the algal coating of Sites IV and V is sbmy, gelatinous, and partly coriaceous, its color ranging from a dark bluish-green to a light ohve green. In Site VI, the algal cover developed on the walls of the mud basins, in a constantly warm, steamy atmosphere above the surface of the water, at a temperature about 37° C. The depth of the coating varies between 0,5 — 2,5 mm, constituting zones above one another. The coating is of a finely granulöse consistency, its color varying from yellowish green to obve green. It is an essential feature of the microvegetations of these habitats that, though all locabties are in the open, the microvegetation is completely identical in winter or in summer, since the hot waters spouting from the depth of the earth cover, by their vapours and gases, the microvegetational biotopes with a constant atmospheric envelope. Schwabe's heterozoic rule of the „umraumfremde Quellen" (Schwabe 1954, p. 544) asserts itself here, too, with some deviation showing only in the virulency of the individuals. SYSTEMATICAL PART In the following chapter, — after long years of study, — I intend to discuss systematically and critically all species and forms of the microvegetation of those biodynamic habitats of the Harkány acrothermae which are free
