Ecologia trófica das assembléias de peixes do reservatório de Chavantes (Medio rio Paranapanema. SP/PR)
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Data
2009-02-16
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Universidade Estadual Paulista (Unesp)
Resumo
Este estudo foi conduzido no reservatório de Chavantes, médio rio Paranapanema, SP/PR, Brasil, sendo o seu objetivo avaliar o papel da compartimentalização deste grande reservatório na distribuição das espécies, partilha de recursos e estrutura e organização trófica das assembléias de peixes. Os peixes foram coletados trimestralmente entre outubro/2005 e julho/2006, com redes de espera, redes de arrasto e peneirão em seis trechos ao longo do gradiente longitudinal do reservatório, representado por dois trechos lóticos (ITA e VER), dois trechos intermediários ou de transição (PAR e FAR) e dois trechos lênticos (BAR e RCL). Foram coletadas 57 espécies no reservatório, sendo que no capítulo 1 apresentam-se a distribuição, abundância e biomassa das espécies nos diferentes trechos, as análises de diversidade (H’), Equitabilidade (E) e β diversidade, e ainda do agrupamento dos trechos de acordo com a abundância das espécies. No capítulo 2 estão apresentadas a composição da dieta, organização trófica, amplitude e sobreposição de nicho trófico de 44 espécies das assembléias de peixes. No capítulo 3 foi analisada a estrutura trófica das assembléias, utilizando-se as variações na abundância e biomassa de 36 espécies pertencentes a 9 guildas tróficas. Os resultados indicam que: 1) as assembléias de peixes apresentam diferenças quanto a composição, abundância e diversidade ao longo do gradiente longitudinal 2) a dieta é um fator importante na segregação das espécies entre os trechos, influenciado pelo elevado consumo de detrito, insetos aquáticos e fragmentos vegetais nos trechos lóticos e intermediários e peixe nos trechos lênticos; 3) as maioria das espécies apresentam alta especialização trófica devido aos baixos valores de amplitude de nicho; 4) a baixa sobreposição de nicho trófico entre os pares de espécies indica...
This study was carried out in the Chavantes Reservoir Middle Paranapanema River, SP/PR, Brazil, to evaluate the role of the longitudinal compartmentalization of this large reservoir in the species distribution, resource partitioning and trophic structure of fish assemblages. Fish were collected every three months from October/2005 to July/2006, with gill nets in six sites along the longitudinal gradient of the reservoir, represented by two lotic (ITA and VER), two transitional (PAR e FAR) and two lentic ones (BAR e RCL). We registered 57 fish species in the reservoir. The chapter 1 presents the distribution, abundance and biomass of fish species, with analysis of species diversity (H’), evenness (E), β diversity, and cluster of the six sites based on the abundance of fish species. The chapter 2 presents the diet composition, trophic organization, niche breadth and niche overlap of 44 species from the fish assemblages. In the chapter 3 was evaluated the trophic structure of assemblages, based in the variation of abundance and biomass of 36 species belonging to 9 trophic guilds. The results indicate that 1) fish assemblages differ in species composition, abundance and diversity along the longitudinal gradient; 2) the diet of fish species is important in their segregation along the sites, affected by the high consumption of detritus, aquatic insects and vegetal matter in the lotic and transitional sites and by fish in the lentic ones; 3) great number of species present high trophic specialization, due to the low values of niche breadth; 4) the low niche overlap observed between pairs indicate that species partition food resources, with no evidence of competition; 5) the high abundance of detritivorous and insectivorous sustain great biomass of piscivorous in many sites. All the results reinforce that longitudinal compartmentalization and environmental aspects of each site are important... (Complete abstract click electronic access below)
This study was carried out in the Chavantes Reservoir Middle Paranapanema River, SP/PR, Brazil, to evaluate the role of the longitudinal compartmentalization of this large reservoir in the species distribution, resource partitioning and trophic structure of fish assemblages. Fish were collected every three months from October/2005 to July/2006, with gill nets in six sites along the longitudinal gradient of the reservoir, represented by two lotic (ITA and VER), two transitional (PAR e FAR) and two lentic ones (BAR e RCL). We registered 57 fish species in the reservoir. The chapter 1 presents the distribution, abundance and biomass of fish species, with analysis of species diversity (H’), evenness (E), β diversity, and cluster of the six sites based on the abundance of fish species. The chapter 2 presents the diet composition, trophic organization, niche breadth and niche overlap of 44 species from the fish assemblages. In the chapter 3 was evaluated the trophic structure of assemblages, based in the variation of abundance and biomass of 36 species belonging to 9 trophic guilds. The results indicate that 1) fish assemblages differ in species composition, abundance and diversity along the longitudinal gradient; 2) the diet of fish species is important in their segregation along the sites, affected by the high consumption of detritus, aquatic insects and vegetal matter in the lotic and transitional sites and by fish in the lentic ones; 3) great number of species present high trophic specialization, due to the low values of niche breadth; 4) the low niche overlap observed between pairs indicate that species partition food resources, with no evidence of competition; 5) the high abundance of detritivorous and insectivorous sustain great biomass of piscivorous in many sites. All the results reinforce that longitudinal compartmentalization and environmental aspects of each site are important... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Peixe - Ecologia - Paranapanema, Rio (SP/PR), Reservatórios, Longitudinal gradient, Trophic guild
Como citar
MAGNONI, Ana Paula Vidotto. Ecologia trófica das assembléias de peixes do reservatório de Chavantes (Medio rio Paranapanema. SP/PR). 2009. 115 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Biociências de Botucatu, 2009.