Influência de diferentes usos de solo na estrutura da comunidade de macroinvertebrados aquáticos em cursos d’água de baixa ordem no município de Cabo Verde - MG

Abstract

Environmental degradation of aquatic ecosystems resulting from anthropic activities have increased significantly in recent decades, mainly due to the growth of urban centers, the increased exploration of natural resources and agricultural expansion. The biological communities that depend of these natural resources are exposed to these impacts, among these, the fauna of aquatic macroinvertebrates. In this context the present study aims to analyze the structure and distribution of aquatic macroinvertebrate community in different surroundings uses. Samples taken in the rainy and dry seasons in 11 low-order streams in the city of Cabo Verde, placed in areas with different surrounding uses (monoculture of coffee and sugarcane, pasture, natural and reforested vegetation). Aquatic macroinvertebrates were sampled with type "D" grid and sampling effort of 3 minutes at a distance of 50 m. The specimens identified up to the lowest possible taxonomic level. The measured abiotic variables were: pH, electrical conductivity, total suspended solids (TDS), dissolved oxygen, stream width, depth of the water column and the flow speed, concentrations of organic matter, clay, silt, gravel and fine sand. For the characterization of habitats was applied an assessment protocol. The results are organized into two chapters. Chapter 1: The results showed that there is a difference in the fauna composition of aquatic insects in relation to the prevalence of surrounding land use. Preserved and reforested areas have better environmental quality than the others for the fauna of aquatic insects. The order Diptera showed the greatest relative frequency among all orders. There was a trend of the orders Coleoptera, Ephemeroptera and Plecoptera associated with non-disturbed areas. Already Trichoptera was mainly related to coffee cultivation points. Chapter 2: in total were collected 300 specimens of aquatic Oligoquetos divided into four families, eight genera and twelve species. The Naididae family showed the greatest richness and abundance, and the Allonais chelata was the most abundant. The points with pasture predominance in the surround were those who had the greatest abundance, the greatest wealth was found in points with the surrounding pasture and preserved area. Through this study, we understand that the type of the surrounding use determines the structure and distribution of both the community of aquatic insects as the Oligoquetos community. And that streams with the surroundings of coffee cultivation presents better environmental condition among areas under cultivation for the insect community.