Distribution of cyanobacteria at the Gelada Cave (Spain) by physical parameters

As part of an extensive study of the caves in the Province of Alicante (SE Spain), the distribution of cyanobacteria and physical data for the Gelada Cave are presented. This cave is 9.4 m deep, 0.9 to 5.0 m high, 1.2 m wide, and is located in a karst region. Photon flux density, relative humidity, and temperature were measured, and the environmental ranges of conditions where growth occurred fluctuated between 0.0008-0.06 mE.m 22 s 21 , 55.0-95.0% and 5.4-18.0 uC, respectively. All the microorganisms determined from the Gelada Cave were cyanobacteria. Other frequently observed groups in caves, such as Bacillariophyta and Chlorophyta, were not detected because the cave was too weakly illuminated and dry. Cyanobacteria were found to be grouped as blue, brown, green, or gray patina according to the sampling sites and their constituent organisms. The primary common stress factor on the distribution of algal communities in the Gelada Cave is light shortage, followed by humidity, lack of nutrients, and temperature. Twenty-two epilithic cyanobacteria were identified, ten of which have not been previously reported in caves. The species studied are included in the Chroococcales order (77.30%), followed by the Oscillatoriales order (13.60%) and by the Nostocales (4.55%) and Stigonematales (4.55%) orders. The extreme values of the environmental parameters are presented for each taxon in this cave.