Does the damming of streams in the southern Amazon basin affect dragonfly and damselfly assemblages (Odonata: Insecta)? A preliminary study

Abstract

Our goal was to investigate whether the loss of riparian forests alters the structure of assemblages and populations of dragonflies and damselflies. We tested the hypothesis that the composition of the odonate assemblages found upstream from dams are significantly different from those found downstream of these barriers. To test the hypothesis, we investigated stream sectors upstream and downstream of three dams located at the extreme of the southern Amazon basin, in the Brazilian state of Mato Grosso. We collected 111 adult odonates, 45 upstream and 69 downstream, representing 18 species, 12 upstream and 10 downstream. The most abundant species was Epipleoneura williamsoni Santos, 1957 (n = 41, 36.9%), followed by Epipleoneura metallica Racenis, 1955 (n = 20, 18%) and Hetaerina curvicauda Garrison, 1990 (n = 17, 15.3%). Statistical ordination separated the different sectors, with the greatest dissimilarity being found between the upstream and downstream I (DS I), and our hypothesis was further supported b...