Algae promote growth of stalagmites and stalactites in karst caves (?kocjanske Jame, Slovenia)

摘要

Growth of stalagmites and stalactites is in karst caves controlled by different parameters. In illuminated cave entrances growth of such carbonate structure is not controlled just by abiotic factors, but also by cyanobacteria. At present just a few examples are known where growth of speleothems is linked with biolithogenic activity of certain organisms. This work presents species composition of stromatolitic stalagmites and of stalactites the growth of which is enhanced by carbonate deposition promoted by cyanobacteria towards sun light. From the cave entrance in Škocjanske jame (Slovenia) in the algal community of stromatolitic stalagmites 35 taxa were identified with a low portion of coccoid cyanobacteria and taxa such asCalothrix sp.,Homeothrix sp. andSchizothrix sp. In carbonate depositions on the illuminated side of stalactites 14, mainly coccoid, cyanobacteria were identified. It seems that such biogenic carbonate formations could be far more widespread in subaerial habitats when algal propagulas meet adequate ecological factors for growth.