Ciliates in coastal dune soils of different stages of development

Abundance and diversity of soil ciliates were studied in the dunes of the North Sea island Norderney (D). Live counts of ciliates were carried out in spring and fall 1999. The eight examined sites show a sequence from freshly thrown sand beach to heath, including primary dunes, white dunes, gray dunes, bushes and forest. Ciliate abundance was low (5–13 ind g–1 dm) in the young sites without humus horizon (beach, primary and white dune), with dominance of hymenostomes and hypotrichs. The dune soils in older stages showed high abundance, between 39 and 264 ind g–1 dm. Here, the Colpodea were the dominant group. Bacterial feeders were highly dominant at all sites. While in young sites nano- and microtrophic ciliates were important, in the older sites the community was much more diverse with fungivorous and omnivorous ciliates in addition. By using ordination methods, the young soil sites separated as a group, but the older sites, which differ clearly in community structure, did not. The results show the importance of organic matter as a factor for abundance and species richness of soil ciliates.