Distribution of chasmoendolithic cyanobacteria in gypsiferous soils from semi-arid environments (SE Spain) by chemical and physical parameters

As part of an extensive study of the gypsiferous regions of the province of Alicante (SE Spain), the distribution of cyanobacteria and chemical-physical data for the Los Cabezos area in Villena are presented. Thirty-five cyanobacteria were identified and maximum photosynthetically active radition, relative humidity and temperature values are shown for each taxon included in the Chroococcales, followed by the Oscillatoriales and the Nostocales. Cyanobacterial growth was chasmoendolithic since the environmental conditions from semi-arid environments were frequently adverse and to escape such hostile conditions these cyanobacteria take refuge within the rock. The presence of chasmoendolithic cyanobacterial communities in gypsiferous substrata had not been previously reported. We identified two different cyanobacterial growth types: a) among gypsum crystals where the patina were greenish-bluish, orange or pinkish formed exclusively by coccoid species, and b) below gypsum crystals with brownish-greenish patina formed by coccoid species and filamentous forms where the genera Nostoc, Scytonema or Tolypothrix predominated and brownish-yellowish patina constituted by coccoid and filamentous species where the genera Leptolyngbya, Microcoleus, Phormidium or Schizothrix predominated. Soil characteristics of the sampling sites were measured and correlated with the number of species which grew at each site: the gypsum concentrations was inversely proportional to the number of species, high cyanobacterial growth increased the nitrogen in the soil and, finally, the number of species of the genus Gloeocapsa decreased when the percentage of stable aggregates increased.