Estrutura de comunidades de turbelários em áreas úmidas da planície Costeira do Sul do Brasil, com revisão da diversidade de microturbelários no país

Abstract

Microturbellarians are abundant in freshwater and marine ecosystems and may occur in moist terrestrial habitats. However, they are seldom taken into account in studies of biodiversity. Most studies on Brazilian microturbellarians had taxonomical purposes and were done in the years 1940-1950. Thus, information on their occurrence and ecological aspects are dispersed throughout several papers. They are generally benthic, found in diverse environments, such as macrophyte beds, among filamentous algae, directly in substratum, among others. The main goals of this dissertation are (1) to summarize the geographical distribution and ecological aspects of microturbellarians recorded for Brazil, indicating the main gaps in their knowledge and possible actions to enhance studies on this group and (2) to analyze the community structure of turbellarians in different classes of palustrine permanent wetlands in Coastal Plain of Southern Brazil. To reach the first goal we made an extensive literature review of all works with microturbellarian in Brazil. To analyse the community structure, we sampled 25 water bodies, with one sample in each wetland, from October 2013 to February 2014, in the middle coast of Rio Grande do Sul. There are 240 species of microturbellarians registered for Brazil, with records distributed in 12 states. However, just three states located in south Brazil have records of 94% of microturbellarian species. A total of 1257 specimens of turbellarians was collected, representing 62 species and 23 genera, from the orders Catenulida, Lecithoepitheliata, Macrostomida, Rhabdocoela and Tricladida in the middle coastal plain of Rio Grande do Sul. Significant differences were found in abundance and richness in relation to vegetal composition (p<0.05), multi-stratified and floating-leaves wetlands had higher abundance than others and multi-stratified and emergent wetlands had higher richness than others, wetlands without vegetation had lower abundance and richness of this study (p<0.001). The community structure of turbellarians were different among wetlands, being influenced by temperature (p<0.05) and dissolved oxygen (p=0.007) were significantly related to ordenation. From the results of this study, it can be seen that the turbellarian assemblage are strongly related to the habitat heterogeneity. Turbellarians need various environments for their occurrence, thus the conservation of all ecosystems is necessary. Knowledge on the systematics and geographical distribution of Brazilian microturbellarians clearly reflect the scientific activity over many years or decades in two states of southeast and southern Brazil. Considering the scant information on this group in Brazil, which is also the situation of the Neotropical microturbellarians in general, some actions should be proposed. First, it would be necessary to sample in the diverse biomes, as well as in the various river and sea basins, based on standardized sampling protocols. Second, it would be necessary to encourage diverse research groups to include microturbellarians and/or turbellarians in general in biodiversity inventories and studies on community structure of invertebrates. Third, it is necessary to increase the number of research groups on microturbellarians, in order to augment the studies on their morphology, systematic, and ecology.