Epiphytic Protozoa [testate amoebae and ciliates] associated with Sphagnum in peatbogs: relationship to chemical parameters

The composition and abundance of microorganisms (testate amoebae and ciliates) dwelling in the water in the patches of Sphagnum palustre L. in three peatbogs with different pH values of the Poleski National Park (Eastern Poland) and their relationship to chemical parameters were studied. From April to October 2005 from each peatbog twice a month, eight samples were collected by washing 10 g of a wet mass of plant material in 50 ml of distilled water. A total of 11 testate amoebae taxa and 32 ciliate taxa occurred among Sphagnum palustre. Testate amoebae and ciliates richness and abundance were significantly greater (33 taxa and> 15 ind. g⁻¹, respectively) in low pH (4.5) peatbog. Generally, the moss dwelling testacean fauna was dominated by cosmopolitan and ubiquitous taxa. Only four testate amoebae taxa (Arcella vulgaris, Assulina muscurum, Hyalosphenia sp. and Euglypha sp.) showed a clear preference for a low pH. Ciliate communities were dominated by Colpodea, Cyrtophorida, Scuticociliatida and Suctorida. In all peatbogs bacterivorous protozoa occurred in the highest numbers (up to 60%), while algivorous and mixotrophic in the lowest (range from 3 to 10%). Moisture conditions appeared to play a key role in determining the distribution pattern of testacean communities, while pH and the content of total organic carbon in water correlated positively with the total numbers or biomass of testate amoebae and ciliates.