Distribuição da Assembleia de Odonata (INSECTA) em riachos com diferentes níveis de conservação em uma região de Ecótono Amazônia - Cerrado

Abstract

Transitions between large biomes, known as ecotones, have unique environmental conditions that support high biodiversity, but they also suffer intensely from agricultural expansion and environmental degradation. This dissertation investigated the influence of different levels of environmental conservation on the Odonata community (dragonflies and damselflies) in streams located in the ecotone between the Amazon and Cerrado biomes, in the southwest and north of the states of Maranhão and Tocantins, respectively. The approach was carried out through standardized sampling in 30 stream reaches distributed among environments classified as conserved, altered, and impacted, evaluating environmental variables and their relationship with the composition, richness, and abundance of Odonata species. Multivariate analyses were applied, including Generalized Linear Models (GLMs) and Threshold Indicator Taxa Analysis (TITAN), in addition to Principal Component Analysis (PCA). The results indicate that environmental integrity significantly influences the structure of the assemblages, with greater richness and abundance of Zygoptera in conserved environments, while Anisoptera showed greater tolerance to altered environments. The indicator species analysis identified sensitive taxa associated with preserved plant cover and a stable microclimate, while TITAN revealed ecological thresholds related to the variables temperature, electrical conductivity, and habitat integrity index. The diversity of Odonata proved to be an efficient bioindicator tool for the environmental quality of the evaluated streams, reinforcing the importance of preserving riparian vegetation and controlling agricultural expansion in the region. In the end, the study shows that ecotones, despite their complexity and richness, remain underexplored in ecological research and demand greater attention in conservation strategies.