The caves are the biodiversity centers for different types of microorganisms, especially for cyanobacteria. They are also present in almost all extreme environments, and their importance in terrestrial ecosystems is greater because of the decreased competition from vascular plants. Cyanobacteria occurring on rocks are epilithic (colonizing the substrate surface), hypolithic (growing under pebbles and small stones), and endolithic (present in an upper layer of rock). There are three limiting factors for cyanobacteria growing in caves: light or its lack, high humidity, and constant temperature. In caves, one can find not only the cosmopolitan cavernicolous species but also rare taxa. Light, transmission, and scanning electron microscopy (SEM), laboratory cultures, as well as molecular phylogenetic studies are important tools in the study of cave cyanobacteria.
Part of the book: Cyanobacteria