Identification of key microhabitats for fish assemblages in tropical Brazilian savanna streams

Abstract

The habitat use by stream fish can provide an understanding of this important component of species niches, and the changes in the availability of certain structures of instream habitats have a strong influence on the occurrence and abundance of fish species. In this study, we identified the interaction networks between fish and microhabitats in 19 streams of three watersheds from the Brazilian savanna, known as the "Cerrado". We also investigated whether the connectance between fish species and microhabitats depends on either the species abundance or availability of microhabitats and verified whether the use of stream microhabitats vary among watersheds. The data for the fish were obtained using standardized fish collections and underwater (snorkeling) observations to record the association of fish species with 11 stream microhabitats. We used the incidence data to calculate the connectance of species with different microhabitats, a Spearman correlation analysis to test the dependence of the connectance to the species abundance and microhabitat availability, and an Analysis of Similarity to test whether the use of stream microhabitats by fish can vary among watersheds. In all of the watersheds, the tetras of the family Characidae used the largest number of microhabitats. The most-used microhabitats by the fish watersheds were the lateral surface, column surface, and unconsolidated substrate, which were differentially used by the fish in each watershed, indicating the variable importance of microhabitats. Despite this observation, the fish occurred more frequently in the lateral microhabitats. When the data for all of the streams were combined, the species connectance was correlated with the species abundance. We also discuss the consequences of the elimination of certain bottom structures in the context of siltation, which is the main issue in the studied region. The results of our study allowed the detection of key microhabitat structures and can be used for the aquatic ecosystems restoration.

Habitat use by Astyanax taeniatus (Jenyns, 1842) (Characiformes: Characidae) in a coastal stream from Southeast Brazil

“…Nonetheless, A. taeniatus was characterized as a pool indicator in another coastal stream of the same basin (Rezende et al, 2010), corroborating the findings of Romero & Casatti (2012) that discuss the adaptive niche plasticity of Astyanax species that allows the species to use a broader array of microhabitats and environmental features. Stream-dwelling fish species can be very plastic and tolerant to environmental changes (Abelha et al, 2001;LuzAgostinho et al, 2006;Menezes et al, 2007;Manna et al, 2012), and differences in habitat availability could be responsible for different patterns of habitat use by this group of species (Schlosser, 1982).…”

More of the Same: High Functional Redundancy in Stream Fish Assemblages from Tropical Agroecosystems

“…Values of 1-9 were assigned to each species to represent its main feeding tactic: 1 = grubber excavating while moving, feeding on bottom animals d ; 2 = picker of items in the water column e ; 3 = crepuscular to nocturnal predator of bottom animals d ; 4 = ambush predator among roots of submerged vegetation e ; 5 = digger of localized excavations, feeding on bottom animals d ; 6 = grazer e ; 7 = surface picker d ; 8 = sit-and-wait predator of bottom animals d ; 9 = mud-eater d a Watson and Balon (1984), b Teresa and Casatti (2012), c Romero and Casatti (2012), d Sazima (1986), e Casatti (2002) Environmental Management…”

Microhabitat segregation and fine ecomorphological dissimilarity between two closely phylogenetically related grazer fishes in an Atlantic Forest stream, Brazil

“…Therefore, beyond all the theoretical implications, an approach drawing on the use of microhabitat may bring important insights to suggest priorities for the improved management of stream systems and their biodiversity. Such approach has been scarcely applied to tropical stream ichthyofauna (e.g., Romero and Casatti 2012).…”