Meso and microhabitat analysis and feeding habits of small nektonic characins (Teleostei: Characiformes) in Neotropical streams

Abstract

The habitat use and feeding habits of a set of nektonic fish species often found in small low-gradient streams in Brazil were investigated. The core species in the present study was Knodus moenkhausii (Eigenmann & Kennedy, 1903), the most abundant of five species in the nektonic guild. Records of the species in 22 streams indicate that K. moenkhausii is associated, on a mesohabitat scale, with runs, and on a microhabitat scale, with sandy bottoms, intermediate depth, and open sites without coverage or submerged vegetation. During snorkeling observations, two additional nektonic registered species showed spatial segregation from K. moenkhausii with respect to foraging microhabitats. Feeding habits of the observed nektonic species were significantly correlated with riparian vegetation. The six species studied appear to use different resources, as suggested by a non-metric ordination of diet, and sites with characteristic riparian vegetation. The studied species may be considered generalists with a tendency to insectivory, with K. moenkhausii feeding on the widest variety of resources. Such opportunism explains its ability to successfully occupy instream habitats with low complexity

Functional differentiation between fish assemblages from forested and deforested streams

“…Species from this group are often dominant in Neotropical streams (Castro, 1999) and were well represented in our streams, except in one of the deforested streams (D2), possibly due to higher water flow and the reduced availability of macrophyte-free space in the water column. Group 6 species are known for their trophic plasticity and opportunism and are capable of successfully using available resources, even in degraded environments (Melo et al, 2004;Ceneviva-Bastos et al, 2010) -which may explain their low sensitivity to deforestation.…”

<b>Co-occurrence patterns of fish communities in littorals of three floodplain lakes of the Orinoco River, Venezuela</b>

“…This could be a strategy of M. eleotrioides to avoid competition. For other characins a partition of foraging patches has been described as a mechanism that might relieve interspecific competition (Ceneviva-Bastos et al 2010 (Malabarba et al 2013). Further research is needed, however, to corroborate our assumptions.…”

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

“…Astyanax taeniatus, as well as many other Astyanax species (Uieda, 1984;Abilhoa et al, 2008), also selected slow to moderate water velocities with bedrock and sandy bottoms. Ceneviva-Bastos et al (2010) observed two Astyanax species associated with sandy bottoms. These patterns of habitat use could be reflecting the feeding tactics frequently described for Astyanax species that forage in the water column, feeding on drift items available throughout the year in these coastal streams (Motta, 1988;Motta et al, 1995;Casatti & Castro, 2006;Gibran, 2007).…”

“…specific behaviors of fish of different ages. Nonetheless, the study site contained all the mesohabitats frequently found in many rain forest streams from the Mata Atlântica (Mazzoni et al, 2011), including a combination of depths, water velocities and substrata, which represented pools, runs, and riffles, creating conditions suitable for high species diversity (Angermeier & Schlosser, 1989;Ceneviva-Bastos et al, 2010). Depths below 30 cm were avoided by the studied species; this is a typical behavior of mid-water pelagic fish (Costa, 1987;Casatti, 2002;Fogaça et al, 2003;Abilhoa et al, 2008).…”

“…The microhabitat parameters selected by Astyanax taeniatus cover a set of characteristics that describe areas of runs similar to those occupied by many Astyanax species from Mata Atlântica streams (Ceneviva-Bastos et al, 2010;Teresa & Casatti, 2013;Costa, 1987;Casatti, 2002;Fogaça et al, 2003;Abilhoa et al, 2008). 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.…”