Landscape effects on the occurrence of ichthyofauna in first-order streams of southeastern Brazil

Abstract

Objective In this study we aimed to understand how extrinsic environmental factors measured in the watercourses and the surrounding landscape influence the ichthyofauna of first-order streams. Methods Data were collected within the Corumbataí River Basin, São Paulo, southeastern Brazil, during the dry season of 2012. We sampled the ichthyofauna in 13 stretches of streams distributed across four river sub-basins. The stretches differed in relation to the presence/absence of riparian forest, the predominant type of matrix and the percentage of forest. Response variables were species richness and the occurrence of functional groups and explanatory variables include both local and landscape structures from the surrounding environment. Local variables comprised the following water quality and structural attributes: pH, temperature, conductivity, turbidity, flow rate, depth, width, type of substrate. Landscape variables included presence/absence of riparian vegetation, type of vegetation, type of matrix, percentage of forest and canopy cover. Results A total of 268 individuals were recorded, which were distributed among 12 species. The landscape structure influenced the occurrence of functional groups in first-order streams, especially allochthonous-feeders, nektonic and hypoxia-intolerant species. The presence of riparian forest was the most important predictor. Species richness was negatively related to the presence of riparian vegetation, supporting the hypothesis that degraded landscapes lead to a reduction in diversity. Conclusion The protection of riparian vegetation is critical to the maintenance of ichthyofauna diversity in first-order streams. The presence or absence of riparian vegetation differently affected the occurrence of species depending on their functional characteristics, particularly those related to the tolerance to hypoxia, source of alimentary items and the position in the water column.

Fish assemblage structure in a Neotropical urbanised prairie stream exposed to multiple natural and anthropic factors

“…In fact, low occurrence and density of individuals of the order Characiformes evidenced effects of urban pollution on fish assemblages (Cunico et al, 2006). The diversity of these nektonic species is positively influenced by the heterogeneity of available habitat (Ferreira & Casatti, 2006; Tibúrcio et al, 2016). Combined effects of available pool habitats and preserved riparian conditions at the more distant downstream reach in the LS would also contributed to the exclusively occurrence of the piscivorous Characiformes H. argentinensis , the largest freshwater fish predator of the Pampa Plain.…”

“…Overall, a reduction in water quality is coupled with less diverse assemblages and few dominant species (Bertora et al, 2018a). Higher species richness and assemblage equitability are associated with larger heterogeneity of available habitats (Ferreira & Casatti, 2006) and larger vegetation cover in preserved riparian corridors (Cetra & Petrere, 2007; Tibúrcio et al, 2016). A high proportion of piscivorous was collected in streams with low total suspended solids, high coverage of macrophytes (Granitto et al, 2016) and high riparian quality (Bertora et al, 2018a; Granitto et al, 2016).…”

Land cover, riparian zones and instream habitat influence stream fish assemblages in the eastern Amazon

“…The strength of the relationship between land cover and fish assemblages is highly variable among regions (e.g., Tiburcio, Carvalho, Ferreira, Goitein, & Ribeiro, 2016). Over the last few decades, the Amazon region has undergone changes in forest cover with impacts to both terrestrial and aquatic ecosystems (Juen et al, 2016;Laurance et al, 2014).…”