SPATIAL DISTRIBUTION OF ARCELLINIDA TESTATE AMOEBAE IN AAPA MOOR AT DIFFERENT SCALES

Abstract

Background. Testate amoebae are an important component of marsh, freshwater and soil ecosystems. Many species have clear environmental preferences, making them useful bioindicators. Currently, more and more investigations are devoted to the study of the structural organization of the testate amoebae communities in different types of biotopes and to the identification of the main causes of changes in the species composition and abundance. However, issues related to the identification of mechanisms that ensure the coexistence of closely related species still remain without due attention. Materials and methods. The study was conducted on the aapa moor, located in the northern subzone of the taiga in the vicinity of the Pertsov White Sea Biological Station, Moscow State University (WSBS MSU). We studied the horizontal distribution of testate amoebae on a macro- (40 × 150 m), meso- (10 × 10 cm), microscale (3 × 3 cm), and vertical distribution in the deep of the sphagnum. Results. In 86 samples revealed 11 574 tests belonging to 109 species and subspecies from 33 genera. Representatives of the order Arcellinida make up a significant share in the testate amoebae community (from 36 to 63 % of the total abundance in different samples). Testate amoebae are characterized by rare joint occurrence in samples throughout the whole aapa moor. The average index of similarity of distributions of the most abundant species (more than 5 % of the total abundance) is 0,2 (Brey – Curtis index). The distribution of the amoebae in the area of 100 cm2 was significantly more homogeneous (the average Brey – Curtis index is 0,78). The distribution of amoebae on a microscale (10 cm2) was very heterogeneous: some species (Hyalosphenia papilio, Heleopera rosea and Heleopera sphagni) show high similarity indices of 0,7–0,78, others (Centropyxis elongata) are characterized by a low level of overlap (average 0,26). The average index of similarity in a microscale is 0,47. The vertical divergence of species is very weak (the average Brey – Curtis similarity index is 0,75). Conclusions. The testate amoebae community is structured mainly due to the differentiation of ecological niches of species on the scale of the whole aapa-mire, as well as individual groups diverge on a microscale. The role of horizontal distribution at the mesoscale and vertical distribution in the divergence of spatial components of ecological niches is significantly lower.

Keywords

• testate amoebae
• protist
• wetland ecosystems
• coexistence of species
• community structure