LOCAL VERSUS GLOBAL DIVERSITY OF MICROORGANISMS - CRYPTIC DIVERSITY OF CILIATED PROTOZOA

Microbial species diversity both global and local, is still poorly und erstood. III this study all species of ciliated protozoa were recorded microscopically from similar to 1 cm(2) sediment collected from a sma ll lake and item a marine shallow-water bay. Additional adjacent sedim ent samples (together representing < 50 cm(2)) were then incubated und er a variety of culture conditions to reveal ''cryptic species'' that are present as resting cysts or are too rare to be found microscopical ly. About 85 and 57% of the total number of observed species from the limnic and marine sediment, respectively, were such cryptic species. I n both cases the number of species found in < 50 cm(2) of sediment rep resented about 75% of all ciliate species ever recorded from these two previously well-studied habitats, and about 8% of all named free-livi ng ciliates. These observations support the assumption thar in the cas e of microorganisms ''everything is everywhere'' and that their global species diversity is relatively limited.