Turbellarian assemblages in freshwater lagoons in southern Brazil

Turbellarians, which typically feed on bacteria, algae, rotifers, oligochaetes, dipteran larvae, microcrustaceans, and other organisms, are abundant in diverse types of wetlands. Despite their importance, abundance, and species richness in freshwater environments, turbellarians are seldom considered in studies on biodiversity. We analyzed the structure of turbellarian communities in shore areas of three categories of permanent wetlands classified according to their perimeter as small, intermediate, and large during an annual cycle. In total, 1847 turbellarians were collected representing 42 species and 15 genera, from the orders Catenulida, Macrostomida, Lecithoepitheliata, Rhabdocoela, and Tricladida. Sixteen species were common to the three categories of wetlands, whereas nineteen species were unique to a particular category. Species composition varied among wetlands of different sizes; small, intermediate, and large wetlands had different dominant species. We found seasonal differences in community composition over the year, but no significant differences in mean values of observed species richness among wetlands with different sizes and among seasonal samples. The estimated species richness was, however, higher in the small wetlands, followed by the large and intermediate wetlands. In the summer, abundance was significantly lower in the small water bodies than in the intermediate and large bodies of water. Our results reinforce the need for conservation of wetlands of different sizes.