In this dissertation, heterotrophic protists in biocrusts from unstudied habitats of German dunes in the Baltic Sea and Icelandic grasslands were investigated. A detailed study of the diversity and community composition of heterotrophic protists revealed the dominance of amoebae and flagellates in dunes biocrusts. Further, taxa from the dominant group Cercozoa were categorized by their feeding behavior. This showed a high amount of protists feeding on bacteria in dunes and grasslands. The detailed investigations in this thesis finally led to the discovery of new protist species in biocrusts.<eng>
