é nozes

Ocorrência e ecologia trófica de quatro espécies de Astyanax (Characidae)...

247

Ocorrência e ecologia trófica de quatro espécies de Astyanax
(Characidae) em diferentes rios da bacia do rio Tibagi, Paraná, Brasil
Sirlei Terezinha Bennemann1, Ana Maria Gealh2, Mário Luís Orsi1 & Leda Maria de Souza2
1. Centro de Ciências Biológicas, Departamento de Biologia Animal e Vegetal, Universidade Estadual de Londrina, Campus Universitário,
Caixa Postal 6001, 86051-990 Londrina, Paraná, Brasil. ([e-mail])
2. Departamento de Biologia Geral, Universidade Estadual de Ponta Grossa, Praça Santos Andrade, s/n., 84010-970 Ponta Grossa,
Paraná, Brasil.

ABSTRACT. Occurrence and trophic ecology of four species of Astyanax (Characidae) in different rivers of the Tibagi
River Basin, Paraná, Brazil. Stretches of the Rivers Fortaleza, Iapó and Tibagi were monthly sampled with gillnets of different mesh sizes and castnets from May 2001 to April 2002 in the Tibagi River basin. Specimens of four species of the Astyanax genera were captured. In order to assess how they use habitat and food resources in the different rivers, their constancy was calculated and the number of specimens was compared by using the Bray-Curtis similarity analysis. The composition (percentage) of food items consumed was ordered by using the Principal Components Analysis (PCA). The proportion of different food items in the diet was assessed and classified according to type (animal or plant material) and origin (allochtonous or autochtonous). The low similarity and constancy showed differences in the type of habitat preferred by the four fish species. Astyanax altiparanae Garutti & Britski, 2000 and A. fasciatus (Cuvier, 1819) were present in the large rivers but were constant only in the Tibagi River. Astyanax eigenmanniorum
(Cope, 1894) was present in all rivers but prefers habitats in the mouth of affluents of large rivers. Astyanax scabripinnis (Jenyns,
1842) was restricted to Fortaleza