Abstract
This study evaluated the differences in composition, abundance and morphology of testate amoebae among different habitats of the same aquatic environment (plankton, aquatic macrophyte and sediment) in the Upper Paraná River floodplain. Triplicate samplings were undertaken monthly at each habitat from April 2007 to March 2008. The structure of the community of testate amoebae was different among the habitats. The species typical for each habitat, according to Indval, were classified by their shell morphology. Arcella species together with Difflugia gramen and Difflugia pseudogramem were more abundant for plankton. Trinema and Phryganella stood out by their abundance and frequency in aquatic macrophytes. Centropyxis was an indicator of sediment. The results indicated a higher frequency of hemispherical and spherical shells in plankton and spherical and elongated shells in aquatic macrophytes. In the sediment, there was a high frequency of elongated species. Our results support the hypothesis that the community of testate amoebae has different structures among the habitats, refuting the idea that the organization of this community in plankton is guided by random events like the resuspension of organisms from the sediment and their displacement from marginal vegetation.
Highlights
Testate amoebae are protists whose protoplasm is inserted into a test with an oral aperture through which the pseudopods emerge during locomotion or feeding (Smith et al, 2008)
In addition to studies of Alves et al (2010, 2012) that evaluated, respectively, two components of species diversity and the relationship between the size structure of testate amoebae in distinct habitats of a marginal lake in the Upper Paraná River floodplain, this study aimed to evaluate the differences in composition, abundance and morphology of testate amoebae among the populations present in these same habitats
No similar trends of an increase or decrease were detected in the number of individuals among the populations present in plankton, aquatic macrophytes and sediment in this period (Figure 2)
Summary
Testate amoebae are protists whose protoplasm is inserted into a test (shell) with an oral aperture through which the pseudopods emerge during locomotion or feeding (Smith et al, 2008). These protists are present in a wide variety of habitats, such as lakes, lagoons, rivers, wet soils, mosses, bogs (Mattheeussen et al, 2005), estuarine environments (Ferreira et al, 2006) and in the marine supralittoral sand (Golemansky and Todorov, 2004). There are few studies that concomitantly evaluate the community structure of these protists in these three habitats within the same environment (Alves et al, 2010, 2012)
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