Abstract
This study investigated the morphological and dietary relationships of the fish assemblage in a stream with an endemic fauna and low species richness. The ichthyofauna was sampled quarterly from September 2011 to July 2012, through the electrofishing technique. The stomach contents of 419 individuals belonging to seven species were analyzed by the volumetric method, and the ecomorphological traits of 30 specimens of each species were estimated. The main food items consumed were detritus, aquatic and terrestrial insects, and other aquatic invertebrates. We observed low levels of trophic niche breadth and diet overlap between most species. The PCA scores indicated the occurrence of three ecomorphotypes. PCA axis 1 segregated at one extreme, species with dorsoventrally depressed bodies, longer caudal peduncles, and well-developed swimming fins; and at the other extreme, species with compressed bodies and peduncles, and relatively larger eyes and anal fins. PCA axis 2 segregated species with elongated bodies and ventrally oblique mouths. The partial Mantel test revealed a significant correlation between diet and morphology, indicating independence from the phylogeny. The patterns observed suggest that the low richness did not result in a broadening of the species' trophic niches, or in the absence of some of the main ecomorphotypes expected.
Highlights
Iguaçu National Park (INP) is known worldwide for the Iguaçu Falls, and represents, in Brazil, one of the largest remaining continuous areas of Atlantic Forest (Tabarelli et al, 2005)
Assemblages of fish in streams of the Iguaçu River basin contain between six and 10 species (Abilhoa et al, 2008), and the basin as a whole contains about 130 species (Baumgartner et al, 2012)
The dietary analysis showed that the main food items consumed by the fish assemblage were detritus, aquatic and terrestrial insects, and other aquatic invertebrates (Table 1)
Summary
Iguaçu National Park (INP) is known worldwide for the Iguaçu Falls, and represents, in Brazil, one of the largest remaining continuous areas of Atlantic Forest (Tabarelli et al, 2005). The fish fauna in these systems and all of the Iguaçu River above the falls is endemic, with about 80% of its species found only in this basin (Garavello et al, 1997; Zawadzki et al, 1999; Baumgartner et al (2012) This pattern is explained by its geographical isolation from the rest of the fish fauna of the Paraná River basin (Garavello et al, 1997). Assemblages of fish in streams of the Iguaçu River basin contain between six and 10 species (Abilhoa et al, 2008), and the basin as a whole contains about 130 species (Baumgartner et al, 2012). This diversity is low compared to other streams or even to other tributaries of similar order in other stretches of the Paraná River basin (Langeani et al, 2007; Delariva & Silva, 2013)
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