Diversidade das assembléias de peixes nas quatro unidades geográficas do rio Paraíba do Sul

Abstract

ABSTRACT. Diversity of fish assemblages in the four geographic units of the Paraíba do Sul river. Diversity patterns of fish assemblages along the four geographic units (upper, middle-upper, middle-lower and lower reaches) of the Paraíba do Sul river were studied aiming to assess spatial (geographic units) and seasonal (wet/dry periods) variations. Twenty-five sites were sampled between December 2002 and March 2003 (summer/wet) and, August to November 2003 (winter/dry). Fish were caught by a standardized effort, using gill nets, cast nets and mesh trays. A total of 81 species were recorded comprised in 9 orders, 29 families and 55 genera. Characiformes showed the highest number of species (28) followed by Siluriformes (23). Perciformes, mainly Tilapia rendalli and Geophagus brasiliensis, and Cyprinodontiformes, mainly Poecilia vivipara and Poecilia reticulata, were the most numerically abundant groups, while Siluriformes, mainly Hypostomus luetkeni, and Perciformes, mainly Geophagus brasiliensis showed the highest biomass. Poecilia vivipara was recorded only in dry period. Spatially, Hoplosternum littorale predominated in the middle-upper reaches, Pimelodus fur, Hypostomus luetkeni, Glanidium albescens in the middle-lower, and Loricariichtys spixii and Prochilodus lineatus, in the lower reach. Number of species and Margalef's richness showed an increase from the upper to the lower river reaches, mainly during the wet period. Species widely distributed along all over the river extent (G. brasiliensis, Oligosarcus hepsetus e P. reticulata) are opportunistic and can use the available resources despite poor environmental conditions, reflecting the state alteration of the river. Differentiation on the physiography throughout the longitudinal extent of the basin does not match shifts in fish assemblages, suggesting that factors associated to habitat alterations could be structuring fish community at local scale. KEYWORDS.Fish assemblages, spatial patterns, fish distribution, ichthyofauna, neotropical rivers. espécies e a riqueza de Margalef apresentaram um aumento do trecho superior para o inferior, principalmente durante o período de cheia. Espécies que apresentaram ampla distribuição ao longo do rio (G. brasiliensis, Oligosarcus hepsetus e P. reticulata) são consideradas oportunistas por se aproveitarem dos recursos disponíveis em ambientes pobres, refletindo o estado de alterações do rio. Diferenciações na fisiografia ao longo da extensão longitudinal da bacia não coincidiram com mudanças nas assembléias de peixes, sugerindo que fatores associados a alterações de hábitats poderiam estar estruturando a comunidade de peixes a nível local. PALAVRAS-CHAVE.Assembléias de peixes, padrões espaciais, distribuição de peixes, ictiofauna, rios neotropicais.O rio Paraíba do Sul é um dos mais utilizados sistemas lóticos do Brasil, por situar-se entre os maiores centros urbano-industriais do país, e tem sofrido alterações de origem antrópica ao longo dos últimos quatro séculos. A intensa urbanização e industrialização são os mai...

Distribution of guppies Poecilia reticulata (Peters, 1860) and Phalloceros caudimaculatus (Hensel, 1868) along a polluted stretch of the Paraíba do Sul River, Brazil

“…In this scope, P. reticulata and P. caudimaculatus have been reported as indicators of poor water condition due to their ability to thrive in harsh environmental conditions (Araújo, 1983). Both species have been recorded along the Paraíba do Sul River mainly in more polluted stretches (Araújo et al, 2001;Teixeira et al, 2005;Pinto et al, 2006b;Pinto and Araújo, 2007). On the other hand, fish condition indicates health and can be influenced by environmental conditions (Vila-Gispert and Moreno-Amichi, 2001).…”

Ichthyofauna diversity of Taperoá II reservoir, semi-arid region of Paraíba, Brazil

“…A good example of this is the coexistence between A. bimaculatus and A. fasciatus in the reservoir, both abundant during the dry seasons. The abundance and coexistence of these two species was also observed by Hoffmann et al (2005), Galetti Junior et al (1990), Agostinho et al (1997aAgostinho et al ( ,1997b, Schifino et al (2004) and Teixeira et al (2005).…”

“…These events play an important role in the organisation and functioning of aquatic ecosystems, inducing adaptive surviving strategies by species, which enhance intra and inter-specific competition, alterations in the community structure, and alterations in the availability of food resources. Teixeira et al (2005) stated that investigating biodiversity, particularly fish assemblage structure and its variation patterns through space and time, is relevant to assess environmental quality, given that fishes occupy different positions in aquatic food webs. According to Wootton (1990), the communities from a specific environment can be analysed according to various aspects, including diversity, richness and evenness parameters.…”

Knodus moenkhausii (Characiformes: Characidae): one fish species, three hydrographic basins - a natural or anthropogenic phenomenon?

“…However, in general, the impact of transpositions of rivers due to hydroelectric power dams are rarely recorded. The Paraíba do Sul River, the most anthropogenically impacted river of Brazil [8], is a well-documented case of the transposition of water by…”