Species richness of testate amoebae in different environments from the upper Paraná river floodplain (PR/MS)

Abstract

This study evaluated the species richness of testate amoebae in the plankton from different environments of the upper Paraná river floodplain. Samplings were performed at subsurface of pelagic region from twelve environments using motorized pump and plankton net (68 μm), during four hydrological periods. We identified 67 taxa, distributed in seven families and Arcellidae, Difflugiidae and Centropyxidae were the most representative families. Higher values of species richness were observed in the lakes (connected and isolated) during the flood pulses. Centropyxis aculeata, Difflugia gramem and D. pseudogramem were frequent throughout the study period. Seasonal variability of species in the channels and isolated lakes was evidenced by beta diversity. Besides that, in the rivers, extreme changes in species composition were verified during the high-water period. Our results highlight the importance of the present study to improve the knowledge about the diversity and geographic distribution of these organisms in Brazil and emphasize the importance of current flow in the displacement of testate amoebae from their preferred habitats, marginal vegetation and sediment.