ECOLOGY OF TESTACEANS (PROTOZOA, RHIZOPODA) IN MIRES IN SOUTHERN FINLAND .1. AUTECOLOGY

The distribution of 38 testacean species (Protozoa: Rhizopoda) and a rotifer, Habrotrocha angusticollis (Rotifera: Bdelloidea) were analyzed by range and weighted average ordination techniques of seven chemical and four physical variables from 90 microsites in virgin mires in southern Finland. Both living and dead individuals were counted and the absolute numbers of individuals per unit area were determined. The absolute numbers varied from 13 to 2300 individuals/cm3. All species or species groups but one, Lesquereusia spiralis, a species of nutrient-rich fen microsites, were found to occur in ombrotrophic sites. Only three species (Arcella discoides, Bullinula indica, and Heleopera sylvatica) were not found in eutrophic sites, whereas the remaining taxa were widely distributed across the ecological gradient from ombrotrophic to eutrophic microsites. Three species, Amphitrema wrightianum, Arcella discoides, and Hyalosphenia elegans were found to be in very low numbers in Sphagnum. All other testacean species were found to be well represented in both Sphagnum and Bryales mosses.