Culturable microorganisms in sandy beaches in south Baltic Sea

The abundance of culturable heterotrophic microorganisms (bacteria, fungi, yeasts, actinomycetes) and their spatial and vertical variability were studied in marine-bay ("Sopot") and open-sea ("Czołpino") sandy beaches (southern Baltic Sea). Among studied microorganisms, halotolerant (13.4 - 308.4 x 10[^3] CPU g[^-1] dry wt of sand) and limnotolerant (7.4 - 69.2 x 10[^3] CPU g[^-1] dry wt. of sand) bacteria predomi.nated in the sand of both beaches. Filamentous fungi, yeasts, and actinomycetes constituted only a slight percentage (0.2-3.0%) of all isolated heterotrophic microorganisms. The numbers of all studied microorganisms were much higher on marine-bay beach characterized by a high level of accumulation of organic matter (4.1 mg g[^-1] dry wt. of sand) than in the sand of the open-sea beach, where the content of organic matter was lower (1.9 mg g[^-1] dry wt. of sand). There were marked differences in the horizonatal profile distribution of heterotrophic microorganisms inhabiting marine-bay and open-sea beaches. In both studied beaches higher numbers of microorganisms were determined in the surface (0-5 cm) than in subsurface (5-10cm) sand layer.