Estrutura e composição da assembléia de Chironomidae (Insecta, Diptera) em córregos de primeira ordem da Mata Atlântica

Abstract

Low-order streams in the Atlantic Forest present high habitat heterogeneity and shelter high diversity of invertebrates. The present study evaluated the structure and composition of the Chironomidae assemblage in mesohabitats of first-order streams located in three areas of biological conservation. Samples of litter in ten pool areas and in ten riffle areas were obtained with the aid of a Surber sampler in different months during the dry period of 2010. Identification of most larvae was at genus level. We found 3665 of Chironomidae larvae in Fazenda Floresta, 4368 in Santa Cândida and 6373 in Ibitipoca. Corynoneura (25.87%) was more abundant in the Fazenda Floresta and Tanytarsus in Santa Cândida (23.28%) and Ibitipoca (20.63%). Estimated richness was observed in Ibitipoca. Difference in the faunistic composition among the streams (DCA and MRPP) were explained based on the geographic distance (Mantel Partial). For mesohabitats, riffles had 8273 larvae of Chironomidae and pools 6133 larvae. Tanytarsus occurred in greater abundance in both mesohabitats. Riffle had a higher estimated richness and it was related to Rheotanytarsus, Onconeura, Limnophyes, Metriocnemus, prox. Paratendipes and Nilothauma in Analysis Indicator Species. The difference in faunal composition between mesohabitats (DCA, ANOSIM) was not explained by the composition of litter (Mantel). The results of this study confirm that the presence of allocthonous material associated with different mesohabitats in lotic environments create spatial heterogeneity and, as a consequence, higher diversity. Moreover, it was possible to attest that the geographic distance among regions, determine different faunistic composition of Chironomidae. Therefore, this work contributed to demonstrate the importance of the conservation of remaining areas of the Atlantic Forest in different locations, because they shelter different faunistic compositions.