The algal vegetation of Neusiedlersee

Abstract

Apart from the considerable fluctuations in the salt concentration of Neusiedlersee resulting from its changeable water level, long-term alterations are detectable in the proportion of the individual ions. Formerly, Neusiedlersee was regarded as a soda lake, but recent research has shown that this is nowadays true only of the southern part, whereas Ca, Mg and SO₄ have greatly increased in the northern section (Neuhuber 1971). A drop in the water level can bring about the drainage of large marginal areas and salt concentrations may rise rapidly. Heavy rains, on the other hand, can lead to a decrease in salinity. In locations of this nature the algae must therefore be able to endure high osmotic stresses in addition to possessing ion-specific resistance. Since algae present in brackish waters on the sea-shore are exposed to similar factors it is not in the least surprising to find algae of marine littoral origin thriving in Neusiedlersee (e.g. Bacillaria paradoxa, Gyrosigma macrum, Enteromorpha intestinalis). Many species found in the lake also exist in other saline inland waters (they will be discussed in more detail in connection with diatoms). A specific soda species is one that is also encountered in other soda waters, e.g. Surirella peisonis, which has been found in Guru Göl in Iran (Löffler 1956) and which was termed a ‘brackish water species bound to soda waters by Hustedt 1959, and Cholnoky 1968.