Abstract
The Mato Grosso is a typical Atlantic Forest stream located on the East coast of Brazil, approximately 70 km from Rio de Janeiro city. From its source at about 800m a.s.l, the stream drains a 30km2 area of the Northwestern part of the municipality of Saquarema, state of Rio de Janeiro and flows into the Saquarema Lagoon system. We hypothesized that fish species occupy distinct mesohabitats, with the prediction that their occurrences and densities differ among the microhabitats of riffles, runs and pools. A 250m-long stretch of the stream located in its uppermost part was selected for this study, where it becomes second-order. Mesohabitat description and their fish characterization were undertaken. Fish sampling was conducted by electroshocking and after their identification and counting, they were returned to the stream. For mesohabitat characterization, a Discriminant Function Analysis (DA) was applied. The total number of samples was estimated by the Zippin method and the recorded densities were used as an Indicator Species Analysis (ISA), followed by a Monte Carlo test for 1 000 permutations. The DA significantly separated the three predetermined mesohabitats (pool, riffle and run) (WL = 0.13, F = 187.70, p = 0.001). We found five species of fishes, belonging to four families and three orders. The fishes Rhamdia quelen, Phalloceros harpagos, Pimelodella lateristriga and Astyanax taeniatus are indicators of the pool environment in the Mato Grosso stream, whereas Characidium cf. vidali is an indicator of the riffle environment. The Monte Carlo test detected non-random mesohabitat use only for P. lateristriga and A. taeniatus in the pools and for Characidium cf. vidali in the riffles. We concluded that the Mato Grosso stream contains three well-defined mesohabitats, with indicator species present in two of these mesohabitats.
Highlights
Rivers and streams may be regarded as hierarchical systems of patches that differ in age, size and environmental conditions
We selected the Mato Grosso stream, where the fish assemblage in this site is essentially composed of five species from three orders and four families: Characiformes - Characidae Astyanax taeniatus (Jenyns 1842) and Crenuchidae Characidium cf. vidali Travassos 1967; Siluriformes - Heptapteridae, Pimelodella lateristriga (Lichtenstein 1823) and Rhamdia quelen (Quoy & Gaimard 1824) and Cyprinodontiformes - Poeciliidae, Phalloceros harpagos Lucinda 2008
The riffle environments were dominated by Characidium cf. vidali, which represented 58% of the individual density (Table 4)
Summary
Rivers and streams may be regarded as hierarchical systems of patches that differ in age, size and environmental conditions Both anthropogenic and natural processes create patchiness across a wide range of spatial scales, resulting in a complex biotope structure (Beisel et al 1998). Many studies have demonstrated high specificity between fish species composition and mesohabitat - some fishes are exclusively recorded in runs or riffles, whereas others are typical inhabitants of pools (Schlosser 1982, Moyle & Senanayake 1984, Bisson et al 1988, Wikramanayake & Moyle 1989, Greenberg 1991, Lobb & Orth 1991, Pouilly 1993) These specificities can be related to a species’ life history, including evolutionary and behavioral processes, physiological and morphological mechanisms (Wootton 1998). Considering the phylogenetic distance and the evident differences in external morphology among these species, we hypothesized that they occupy (in different occurrences and densities) longitudinal mesohabitats (riffles, runs and pools)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
