Influência da integridade do habitat e das variáveis ambientais sobre a comunidade de Odonata em igarapés florestados em Roraima

Abstract

The Amazon forest has been suffering environmental impacts resulting from changes in land use for anthropic purposes. One of these impacts is the alteration of the riparian forest, which is responsible for protecting and providing resources and conditions for aquatic biodiversity, its removal or reduction can generate negative effects for the aquatic insect community. The objective of this work was to evaluate the effect of environmental variables and environmental integrity on the Odonata community in forested streams in the Amazon. We tested the hypotheses that: I. Intact forested streams positively affect the richness and abundance of species of the suborder Zygoptera and negatively affect species of Anisoptera and II. Environmental variables, dissolved oxygen, riparian forest width, water temperature and electrical conductivity influence the richness, abundance and composition of Odonata species in forest streams. Fourteen streams were sampled, where we applied the Habitat Integrity Index (IIH) to assess the environmental preservation status and measured environmental metrics such as riparian forest width, dissolved oxygen, electrical conductivity and water temperature. 188 specimens of Odonata were collected, distributed in four families, 13 genera and 27 species. Of the 27 species, 12 are new records for the state of Roraima. The environmental integrity (IIH) ranged between 0.432 and 0.887. The decrease in the physical integrity of the streams did not have a significant effect on the richness and abundance of the order Odonata, however we found a positive relationship between the width of the riparian forest and the species richness of the suborder Zygoptera. We also highlight that other metrics such as water temperature, riparian forest width and flow affected the richness and abundance of the Odonata community. The positive relationship of zygopters with the increase in riparian forest width may indicate a positive relationship of this suborder with environments that have more intact riparian forest. Habitat integrity showed no effect on the Odonata community. This fact may have occurred due to the low variation in the integrity of the streams, as 11 streams had high levels of integrity. The positive relationships of environmental variables with the Odonata community demonstrated that environmental characteristics such as riparian forest width and water temperature are important metrics for structuring the dragonfly community.