Importance of lateral lagoons for the ichthyofauna in a large tropical reservoir

Abstract

This study aimed to analyse the composition and the ecological attributes of small-sized fish assemblages in four lagoons and in the main channel of Rosana Reservoir (SE Brazil). Fieldwork was carried out in September and November/2004 and January, March, May and August/2005. In each sampling station and period five manual throws were performed towards aquatic macrophyte stands, using a hand net (1.5 × 5 m; 0.3 cm of mesh size). The ichthyofauna collected was represented by 42 species, totalizing 3,424 individuals, 2,186 g in weight. The order Characiformes was dominant, mainly in the lagoons with low connectivity with the river. The main taxon (Importance Index) was Hemigrammus marginatus. Higher richness, abundance, biomass, diversity and lower individual mean length were observed in the lagoons, especially during the rainy period. Spatial segregation of some species was showed by the canonical correspondence analysis indicating the habitat complexity. The results validate the hypotheses that lateral lagoons have a prominent ecological role in the life cycle of juveniles and small fish and demonstrate how the connectivity river/lagoons may be important for assemblages maintenance.

Ecomorphology and use of food resources: inter- and intraspecific relationships of fish fauna associated with macrophyte stands

“…Considering a method adopted by Casatti et al (2003), Ferrareze & Nogueira (2011) and Gomes et al (2012), fish were collected with a 1.0 m x 1.5 m sieve, 0.05 mm mesh, which was passed three times across each macrophyte stand from the bottom to the surface. Thus, different sizes of fishes were captured (CP of 5.45 mm to 36.06 mm).…”

Differences in ichthyofauna feeding habits among lateral lagoons and the river channel in a large reservoir

“…They exhibit a clear segregation among river and lagoons segments. In lagoons, a higher number of trophic guilds are represented as well as higher values of niche amplitude and lower values of niche overlap, despite the greater abundance of fish living in these environments (Ferrareze and Nogueira, 2011a). This result confirms the importance of lateral river lagoons and other kinds of floodplain habitats for fish ecology, including feeding processes (Hahn et al, 1997b;Meschiatti and Arcifa, 2002;Crippa et al, 2009).…”

“…Thus, reservoirs can endanger local ichthyofauna once they transform a lotic and diversified system in a more simplified lentic environment (Agostinho et al, 2008). The effects of reservoirs can extend to lateral lagoons and other floodplain habitats that are of major importance for the ichthyofauna life cycle , especially for small-sized species (Ferrareze and Nogueira, 2011a).…”

New occurrence of a non-native ornamental cichlid in the Paranapanema River, southern Brazil

“…The female fertility varies between 338 and 1,602 oocytes (Souza-Filho and Casatti, 2010), which is considered high in relation to its size, and in comparison to other cichlids, i.e., Cichlasoma paranaense Kullander 1983 (Casatti et al, 2003;Pelicice et al, 2005;Ferrareze and Nogueira, 2011;Orsi, 2010). Spawning occurs in circular nests located at sandy bottoms, and next to roots and macrophyte leaves.…”

“…(Graça and Pavanelli, 2007;Langeani et al, 2007). However, previous studies still had not registered its introduction to the Paranapanema River basin (Casatti et al, 2003;Pelicice et al, 2005;Ferrareze and Nogueira, 2011;Kipper et al, 2011). Only one specimen had been registered at the Rosana Hydroelectric Reservoir in April of 2012 (NUP 13838) (Figure 2).…”