Determinantes da estrutura de comunidades de insetos aquáticos em riachos na Amazônia: o papel do habitat e da escala especial

Abstract

Aquatic ecosystems are highly complex environments, mainly due to interactions between their abiotic and biotic components; they are dependent on variation in physical structure and limnological characteristics, which in general, are factors that specifically act on different spatial and temporal scales. Therefore, considering this complexity in structuring stream habitats, particularly in Amazonian lotic ecosystems, this doctoral thesis aims to evaluate which are the determining factors to structure aquatic insect communities and their distribution according to environmental variation and geographical distances. To meet this goal the thesis is divided into four chapters. In the first, a systematic revision was carried out with a global assessment about the use of insects (Chironomidae: Diptera) in monitoring aquatic ecosystems and their responses as bioindicators. We found that the main issues presented in the studies were related to anthropogenic impacts on aquatic ecosystems and the taxonomic difficulties on the use of species identification to biomonitoring. The second shows analysis of distribution patterns and diversity of Chironomidae communities, under predictions of Metacommunity models, to evaluate the relations of the assemblages with the spatial scale and the environment. The main results showed that the assemblages were mainly affected by components of the physical habitat structure and partly the communities were limited by dispersal among the streams when considered at large scale in the region studied. The third showed analysis of functional composition on the communities of aquatic insects (Coleoptera, Diptera, Ephemeroptera, Hemiptera, Lepidoptera, Megaloptera, Odonata, Plecoptera, Trichoptera) and their responses to variation in habitat structure considered under the assumptions of the Habitat Templet. Overall, we found relationships between the distribution of morphological and functional traits with the physical habitat variables. The fourth chapter evaluates the effect of spatial distance on the community similarity of Ephemeroptera, Trichoptera, Plecoptera communities in two regions of Eastern Amazon. In this final chapter, we find differences in the composition of communities expressed as species replacement because of the geographical distance and local environmental characteristics of each region. Finally, the studies developed in this thesis summarized how the structure of the habitat of streams can affect the aquatic insect communities and variation in the riparian structure and physical habitat, can cause variation in taxonomical composition and functional attributes. In summary, from these findings, we conclude that the physical habitat variables are determining factors in structuring aquatic insect communities. In addition, it is highlighted the importance of local factors (riparian vegetation structure/composition of substrates/limnological characteristics) as explanatory variables for taxonomical and functional composition. In addition, the regional factors (geographical distance / dispersal limitation) are essential components to affect similarity and structure of the communities.