Community structure and distribution of ciliated protozoa in a freshwater pond covered by lemna minor

Abstract

Ciliated protozoa living over a one year period in a small pond covered by a dense floating bed of Lemna minor were identified. The total number of taxa observed was 40, and the correspondence of each taxon with the habitats of surface layer and water-sediment interface was noted. The ciliate taxocoenosis in the surface layer covered by duckweed had a higher number of species than that in the water-sediment interface. Two distinct communities of ciliates were observed in the pond. Nevertheless, an overlap existed between the two communities due chiefly to the large heterotrich Spirostomum teres that had become the predominant species. This population reached a peak in late autumn-winter at the watersediment interface, related to the litter decomposition. During spring and summer, when at the bottom waters anoxic conditions were established, S. teres migrated toward the surface layer and reached the highest values of density. © 1991, Taylor & Francis Group, LLC.