Variação temporal na diversidade de Ephemeroptera em um riacho temporário no cerrado

Abstract

Objective: The research aimed to evaluate the distribution of Ephemeroptera diversity throughout the hydrological cycle in an intermittent stream in the Cerrado. Methods: Collections were carried out in a 150-meter stretch of a single stream, biweekly, from April to August 2023, covering the rainy, transition and dry seasons. The 150-m stretch was divided into 15 equidistant longitudinal sections of 10 m, where the substrates and specimens were collected with the help of a D-net. The specimens were stored in Eppendorf tubes with 90% ethyl alcohol and identified to the genus level. Simultaneously, the physical and chemical characteristics of the stream, such as pH, dissolved oxygen, conductivity, water temperature, depth and width in each section of the stream, were evaluated. Within four months, there was a significant reduction in stream width and dissolved oxygen, in addition to an increase in conductivity during the dry season. Results: A total of 3,473 individuals were collected, belonging to 05 families and 13 genera. Callibaetis was the most abundant, with approximately 2,295 individuals, while Aturbina and Traverhyphes presented only 1 individual each. The genera of the Caenidae Family (Caenis and Brasilocaenis) were found throughout the study, regardless of the ecosystem dynamics, with greater abundance in the transition period (175 individuals) and the presence of a rare genus, Cloeon. Conclusions: These animals can survive even when they move from a lotic to a lentic environment for reasons such as the "storage effect", where the temporarily formed pools function as islands that help in the colonization of habitats when the flow resumes, causing the dispersion of both nymphs and adults. The permanence of these genera indicates that they can be used in monitoring intermittent streams in the Cerrado.