Ökologische und systematische Studien über das Neuston alpiner Kleingewässer, mit besonderer Berücksichtigung der Ciliaten.

Abstract Ecological and Systematic Studies on the Neuston of Alpine Pools, with Special Regard to Ciliated Protozoa The qualitative and quantitative composition of the neuston of 31 alpine pools with different degrees of organic pollution was investigated. Phytoflagellata and Ciliophora dominated in highly eutrophic pools, Phycomycetes in less eutrophic ones. The light‐dependent migration of the photoautotrophic heloneuston from the plankton to the surface film caused a strong depression of the neustonic Phycomycetes. Ciliates specially adapted to a neustonic mode of life were not found. The morphology, infraciliature, silverline system and ecology of nine species occuring more frequently in the hyponeuston were studied. A new species ( Kreyella minuta )., a new genus ( Pseudochilodonopsis ). and a new family (Kreyellidae). are described. Some problems dealing with the ecology of ciliates in the surface films of natural pools and of enrichment cultures are discussed.