Effects of small changes in riparian forest complexity on aquatic insect bioindicators in Brazilian subtropical streams

Abstract

Riparian forests have positive effects on water quality and biodiversity. However, most studies have only tested the effects of distinct vegetation types or streams with and without forests, despite the fact that riparian forests differ in degrees of complexity. The aim of the present study was to test whether riparian forest complexity affected the composition and abundance of the Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa across a small environmental gradient. We also measured whether EPT genera or feeding groups responded to changes in riparian forest complexity. The study was conducted in two protection areas (i.e. Lagoa do Peri Municipal Park, PERI; and the Permanent Protection Area of Ratones, RAT) of Santa Catarina Island, Brazil. Primary production increased in streams with lower canopy percentage, and EPT assemblages differed among streams with different riparian forest complexity. In RAT, the water quality and forest variables affected EPT composition; however, in PERI, only water quality variables were important. Indicator species analysis based on genera suggested Kempnyia (Plecoptera) and Zelusia (Ephemeroptera) to be indicative of streams with greater forest complexity, whereas Farrodes (Ephemeroptera) was significant in streams of intermediate riparian forest complexity; however, no one functional group dominated. The results of the present study show that small changes in riparian forest complexity influence the composition of EPT insects in subtropical streams.

Environmental drivers and composition of assemblages of immature odonates (Insecta) in a subtropical island in southern Brazil

“…In the UCAD, five stream reaches were sampled in the summer of 2012 (February) ( Figure 1). Family-level studies on aquatic insects have been conducted in these areas by Pires et al (2015) and Siegloch et al (2016).…”

Effects of riparian vegetation width and substrate type on riffle beetle community structure

“…Allochthonous organic matter is the main energy source for benthic invertebrates in forested streams, and therefore has an important role in the trophic structure of aquatic communities (Vannote et al ; Tank et al ). Thus, removal or changes in riparian vegetation width can alter not only stream water quality, but also the structure of macroinvertebrate communities (Heino et al ; Lee et al ; Li & Dudgeon ; Siegloch et al ). Decreases in overall richness (e.g.…”

Influence of different riparian vegetation widths and substrate types on the communities of larval Odonata (Insecta) in southern Brazilian streams

“…However, most of the aforementioned studies assess the effects of the conversion of riparian vegetation to anthropic land uses rather than variation in riparian vegetation widths (i.e., broadly corresponding to the amount of forest cover). The effects of reductions in the riparian vegetation width on stream insect communities and particularly on Odonata remain, in general, largely unknown in subtropical regions of Brazil, where fewer studies have been carried out (Siegloch et al, 2017). In this sense, recent studies showed that changes in the amount of forest cover affect the composition of odonates, as detected by Rodrigues et al (2016Rodrigues et al ( , 2019 and Valente-Neto et al (2016) in streams running through the transition between semi-deciduous and savanna landscapes.…”

“…land use, and is assumedly of high importance in subtropical regions, where the input of material to streams is constant (Allan & Castillo, 2007). For instance, Siegloch et al (2017) demonstrated that even small changes in the complexity of the riparian vegetation (e.g. canopy coverage, tree and shrub sizes) elicited changes in aquatic insects in southern Brazilian streams.…”