Changes in the testacean community structure along small soil profiles

Abstract

The testate amoebae (Protozoa, Rhizopoda) fauna was studied along several small soil profiles, which were collected in the wet valley soils of Île de la Possession (Crozet Archipelago, sub-Antarctica). All soil cores were divided into 3 zones (0-3 / 3-6 / 6-10 cm) and results were compared with an earlier soil study on the island, when soil samples were taken at a depth of 5 to 10 cm. There was no turn-over of testacean taxa between the different soil layers, but the changes in the community structure of the communities along the soil horizons were remarkable. In the upper soil layers (0-3 cm) more taxa belonging to characteristic morphological soil test types were observed, test types which were rarely encountered in the soil samples taken at a depth of 5 to 10 cm. The genera Assulina, Centropyxis, Corythion, Heleopera and Nebela were more abundant in the upper soil horizons, which led to a reduced dominance of the genus Trinema. Also the living fraction of the testacean fauna was significantly higher in the upper soil zones, whereas the highest amount of cysts was observed in the lowest soil horizon (6-10 cm). Some notes are made on the different disappearance patterns of "Filose" and "Lobose" taxa along the valley soil profiles of Île de la Possession. All observed changes along the small soil profiles emphasize the importance of the soil sampling strategy.