The epilithon of a cooling tower of the power plant at Bełchatów, Poland

We studied the diversity of the photosynthetic microscopic epilithon overgrowing the concrete walls of a cooling tower of the power plant at Bełchatów, central Poland. Epilithon samples were collected from the open upper part of concrete walls of a cooling tower in March 2006 and examined in labs as dried material in September 2006, and again in March 2011. The aerophytic assemblages were strongly dominated by a nostocalean cyanobacterium, Scytonema myochrous C. Agardh ex Bornet et Flahault. Other cyanobacteria and algae occurred very sporadically and in low abundance. The trichome morphology of S. myochrous growing directly on the tower differs considerably from that of lab-cultured ones. Trichomes from field material were very long, conspicuously sheathed and dark brown, with relatively sparse ramification and with cylindrical cells and heterocytes. Trichomes cultivated in the laboratory were shorter and thicker, with thin, hyaline sheaths which were not layered; they were frequently ramified, and the cells and heterocytes were discoid. Besides Scytonema myochrous, the first revitalized cyanobacteria growing in laboratory conditions included Nostoc sp., Leptolyngbya gracillima (Zopf ex Hansgirg) Anagnostidis et Komárek, and Gloeothece rupestris (Lyngbye) Bornet in Witrock et Nordstedt.