Biochemical comparison of two Hypostomus populations (Siluriformes, Loricariidae) from the Atlântico Stream of the upper Paraná River basin, Brazil

Two syntopic morphotypes of the genus Hypostomus - H. nigromaculatus and H. cf. nigromaculatus (Atlântico Stream, Paraná State) - were compared through the allozyme electrophoresis technique. Twelve enzymatic systems (AAT, ADH, EST, GCDH, G3PDH, GPI, IDH, LDH, MDH, ME, PGM and SOD) were analyzed, attributing the score of 20 loci, with a total of 30 alleles. Six loci were diagnostic (Aat-2, Gcdh-1, Gpi-A, Idh-1, Ldh-A and Mdh-A), indicating the presence of interjacent reproductive isolation. The occurrence of few polymorphic loci acknowledge two morphotypes, with heterozygosity values He = 0.0291 for H. nigromaculatus and He = 0.0346 for H. cf. nigromaculatus. FIS statistics demonstrated fixation of the alleles in the two morphotypes. Genetic identity (I) and distance (D) of Nei (1978) values were I = 0.6515 and D = 0.4285. The data indicate that these two morphotypes from the Atlântico Stream belong to different species

Fish assemblage structure of the Ipanema River, a small lotic environment partially protected by a Conservation Unit in southeastern Brazil

A study on the fish assemblage of the Ipanema River, a small affluent of the Tietê River basin in southeastern Brazil, was performed aiming to look for structural patterns of species diversity in small lowland lotic environments. Fish samplings were performed every two months from June 2003 to April 2004 at four sample sites located on the lower stretch of the river. Local assemblage showed to be species rich, with fifty-two species belonging to Characiformes (25 spp.), Siluriformes (19 spp.), Cyprinodontiformes (3 spp.), Gymnotiformes (2 spp.), Perciformes (2 spp.), and Synbranchiformes (1 sp.). Fish fauna was composed of small-sized species (<200 mm SL) and by individuals of medium (up to 400 mm SL) to large (more than 400 mm SL) sized species. The Ipanema River, such as other small lotic transitional environments in the upper Paraná River drainage, is considered important for conservation of fish fauna because they cover available habitats for persistent populations of small-sized species and for non-persistent individuals or shoals of medium and large-sized fish species, which occupy other habitats along their life-history (e. g. floodplains, oxbow lakes, main channel of great rivers). The importance of the Ipanema River basin for fish fauna conservation is also reinforced by the fact that it is located in a highly impacted region of southeastern Brazil, near the São Paulo metropolitan area

Fish assemblage structure of the Ipanema River, a small lotic environment partially protected by a Conservation Unit in southeastern Brazil

A study on the fish assemblage of the Ipanema River, a small affluent of the Tietê River basin in southeastern Brazil, was performed aiming to look for structural patterns of species diversity in small lowland lotic environments. Fish samplings were performed every two months from June 2003 to April 2004 at four sample sites located on the lower stretch of the river. Local assemblage showed to be species rich, with fifty-two species belonging to Characiformes (25 spp.), Siluriformes (19 spp.), Cyprinodontiformes (3 spp.), Gymnotiformes (2 spp.), Perciformes (2 spp.), and Synbranchiformes (1 sp.). Fish fauna was composed of small-sized species (<200 mm SL) and by individuals of medium (up to 400 mm SL) to large (more than 400 mm SL) sized species. The Ipanema River, such as other small lotic transitional environments in the upper Paraná River drainage, is considered important for conservation of fish fauna because they cover available habitats for persistent populations of small-sized species and for non-persistent individuals or shoals of medium and large-sized fish species, which occupy other habitats along their life-history (e. g. floodplains, oxbow lakes, main channel of great rivers). The importance of the Ipanema River basin for fish fauna conservation is also reinforced by the fact that it is located in a highly impacted region of southeastern Brazil, near the São Paulo metropolitan area

Fishes from the Itapecuru River basin, State of Maranhão, northeast Brazil

The Itapecuru is a relatively large river in the northeastern Brazilian state of Maranhão. During several expeditions to this basin, we collected 69 fish species belonging to 65 genera, 29 families and 10 orders. Characiformes and Siluriformes were the orders with the largest number of species and Characidae, Loricariidae, Cichlidae, Auchenipteridae and Pimelodidae were the richest families. About 30% of the fish fauna of the Itapecuru basin is endemic or restricted to northeastern Brazil. Just over a fifth (22%) of the species is also known to occur in the Amazon basin and only a few are more widely distributed in South American