Chlorophyll-a and Suspended Inorganic Material Affecting the Shell Traits of Testate Amoebae Community

Shell composition is considered an important functional trait in testate amoebae community. Differences in the composition of shells may represent adaptations of these organisms to changes in the availability of environmental resources. We aimed to evaluate the influence of these environmental resources on the presence of different testate amoeba species, based on observation of one important functional trait (shell composition), in floodplain environments. We hypothesised that species diversity would increase with increased availability of food (chlorophyll-a; a critical environmental requirement). We also predicted that a higher concentration of suspended inorganic material would contribute to the occurrence of species that have an exogenous shell. Testate amoeba samples were taken between 2002 and 2011 in plankton of ten floodplain environments. A significant positive correlation was noted between the concentration of chlorophyll-a and the diversity of testate amoeba species according to a simple regression analysis. Furthermore, non-metric multidimensional scaling showed distinct groups with lower and higher concentration of suspended inorganic material. The occurrence of testate amoeba species with smaller exogenous shells was the most influenced by environments with higher concentrations of suspended inorganic material. Thus, our results emphasised that the evaluated environmental resources are important as assembly factors to shell traits in testate amoebae community.