Half a century of research on diatoms in athalassic habitats in central Poland

Part of the geology in the Lodz province was formed during the Upper Permian period when rich Zechstein salt was deposited. Groundwater drains the deposits and flows out in the village of Pelczyska, creating a unique hydrogeological site in Central Poland. An inland, athalassic ecosystem can be a reference site for halophile microflora. The outflow with surrounding marshes has been an algological research site since 1964. The research reveals changes recorded in diatom assemblages from athalassic habitats, characterized by a wide range of salinity levels, and verifies the tolerance of taxa to salinity. The comparative analysis was based on the diatom material sampled in 1964-1965, 1992-1994 and on recently collected samples. The analysis revealed the temporal change in assemblages caused by a change in the chloride concentration, and the spatial change from one to another habitat type, characterized by varying salinity levels. The halophilic species in the studied habitats included e.g. Halamphora dominici, H. tenerrima, Navicula digitoconvergens, N. meulemansii, Staurophora salina. The analysis of changes allowed the verification of the species' requirements and tolerance range to the salinity factor. Therefore, in the case of Fragilaria famelica and Halamphora sydowii, we propose a change in the halobion system classification.