Testacean communities in perturbed soils: the influence of the wandering albatross

摘要

On Ile de la Possession (Crozet Archipelago, sub-Antarctica), the testate amoebae (Protozoa, Rhizopoda) fauna in soils around abandoned and occupied nests of the wandering albatross (Diomedea exulans) was investigated. A comparison with control samples, a cluster analysis and several ordination techniques indicated that the presence of the breeding albatrosses induced modifications in physico-chemical soil characteristics and in the soil inhabiting testacean fauna. Only 11 testate species occurred frequently in the soils in the albatross' zone. Soils around occupied nests had significantly higher moisture values, less acid pH values, an increased specific conductance and elevated phosphate and ammonium concentrations. Highly influenced testacean communities were characterised by high abundances of Difflugiella oviformis and extremely high abundances of Trinema lineare, resulting in a very low diversity and evenness within these communities. The intermediary situation of one abandoned nest indicated that soils around abandoned nests evolve gradually back to undisturbed soils. Although an overall negative influence on the testacean diversity, a limited albatross' influence may increase the living fraction within the testacean soil communities.