Fine structure of a terrestrial cyanobacterial mat from Antarctica

The fine structure of a cyanobacterial mat collected from the fellfield ecosystems of Signy Island, Antarctica, was examined using some novel light and scanning electron microscope techniques. The mat was up to 5 mm thick and was distinctly layered. The surface of the mat consisted of nonliving material above a zone of Phormidium autumnale (Ag.) Gom. filaments. We suggest that the surface layer protects the cyanobacterium from the effects of desiccation or high irradiance. Lower layers were less structured than the upper layer and included other taxa of cynobacteria and eukaryotic algae, although still dominated by Phormidium. The lowest layers consisted of dead organic material. The mat bound large amounts of inorganic material within and between the subsurface layers.