Aplicação das proporções de Zygoptera e Anisoptera (Odonata:Insecta) para monitorar a integridade ambiental de riachos de Cerrado

Abstract

The natural landscapes of the Cerrado are increasingly altered due to the conflicting development model between economic growth and the maintenance of ecosystems and their biodiversity. The total or partial suppression of the natural vegetation of the Cerrado promotes greater entry of light into the streams. Due to the thermoregulation characteristics, the higher light intake alters the communities of Odonata (Insecta) causing an increase in the proportions of the suborder Anisoptera and the decrease of the suborder Zygoptera. Our objective was to verify whether the proportion of individuals and the proportion of species richness of Zygoptera and Anisoptera change due to the loss of environmental quality of Cerrado streams. The study was conducted in 18 streams in the municipalities of Nova Xavantina and Nova Nazaré, MT. In each stream, communities of Odonata were collected and their environmental integrity was measured using the Habitat Integrity Index (IIH). To evaluate the environmental quality of Cerrado streams, we made four simple linear regression models using in each model the proportion of species richness and abundance of individuals of the zygoptera and anisoptera suborders as response variable and IIH values as a predictor variable. Together, 38 species and 514 individuals of Zygoptera and 49 species and 664 individuals of Anisoptera were collected in a gradient of environmental integrity represented by the IIH ranged between 0.118 and 0.963. All regressions demonstrated that the loss of environmental integrity causes a decrease in Zygoptera and anisoptera increase: Zygoptera% richness with IIH (r2= 0.506, p= 0.0009), Anisoptera % richness with IIH (r2= 0.506, p= 0.0009), abundance of Zygoptera % with IIH (r2= 0.445, p= 0.0025) and abundance of Anisoptera % with IIH (r2= 0.445, p= 0.0025). From our results we can conclude that the proportions of Zygoptera and Anisoptera may be an indicator of environmental quality of cerrado streams, as has been observed by other authors in streams of the Amazon and the Atlantic Forest.