Ecological evaluation of air and water habitats in the Great Cavern of Santo Tomás, Cuba

Air and water habitats in the Great Cavern of Santo Tomás were investigated using cultivable indicator microbial groups. In addition, cave pools were sampled to evaluate the biomass and diversity of aquatic meiofauna. In the climatically dynamic entrance part named Cueva de las Antorchas, concentrations of total cultivable airborne bacteria ranged from 2 to 15 CFU/20 cm2/20 min, and of airborne yeasts and moulds from 2 to 23 CFU/20 cm2/20 min. Different pools fed by constant percolation water or occasional underground floods were sampled. Microbial indicators of water habitats (total bacteria, coliforms, Escherichia coli, Enterobacteriaceae) showed that microbial load very likely depended on the sampling position in the vertical transection of the cave system and closeness to the entrance. During the underground flow of Santo Tomás Stream through the cave system, the concentration of isolates typical for E. coli was reduced from 56 CFU/ml at the ponor in Valle de Santo Tomás to a concentration below the detection limit at the spring in Valle de Quemado. In some cave pools, apart from microorganisms, aquatic fauna contribute highly to the total biomass. Investigation for aquatic meiofauna diversity in cave pools revealed relative high abundances of copepods and ostracods