Assembleias de ephemeroptera, plecoptera e trichoptera em riachos tropicais

Abstract

This thesis was divided into two parts, the first of which aimed to address the influence of mesohabitats riffle and pools and land use on assemblage of Ephemeroptera, Plecoptera and Trichoptera in tropical streams. For the first chapter, the collection was performed only once in the month of August of the year 2012 in three forested streams, three streams in pasture and three streams urban located in the region of Juiz de Fora, Minas Gerais, Brazil. At each stream, the substrates were collected in five riffle and five pools with Surber sampler. The principal component analysis (PCA) and Detrended correspondence analysis (DCA) showed separation of streams for the different land uses, as well as the distinction between riffle and pools. Phylloicus was the most abundant genus in pool and Smicridea the most abundant genus in riffle. Both genera were abundant in forested streams. Hydroptilla, Americabaetis and Oxyethira were the most abundant in the rate of pasture and urban streams. Data from this study confirm the expected composition of the assemblage of EPT between different land uses and between mesohabitats, which helps to emphasize the importance of physical habitat heterogeneity and the presence of riparian vegetation for greater richness and diversity of EPT difference. Additionally, riffle and pool were similar in detecting the effect of land use, which allows us to suggest the use of only one of mesohabitats when using the EPT meeting in studies aimed at diagnosing the ecological conditions in lotic ecosystems of low order. In the second chapter were verified the effects of periods of rain and drought in different land uses on the assemblage EPT, the same locations , and also the same methodology for this research, with the difference that this held in February (period rainy) and August (dry season) , and sampling occurred only in tubing to reduce the effect of spatial variation. The temperature and turbidity were the most correlated with the rainy season in all areas of environmental variables on PCA. The faunal similarity was high between periods of rain and drought in streams with different landscapes according to the permutation test for homogeneity of multivariate dispersion (PCoA). However, some genera such as Farrodes, Leptohyphes, Americabaetis, Nectopsyche and Paragripopteryx were considered indicators of the dry period in streams under different land uses. The study results show that the rainfall was not able to lead to disruption of assemblage EPT, independent of the characteristics of the surrounding streams. However, Farrodes, Leptohyphes, Americabaetis, Nectopsyche and Paragripopteryx seem to be affected by increased rainfall being recorded in greater abundance and frequency only in the dry season.