Padrões espaciais e temporais na estrutura de assembleias de peixes de lagos de várzea: efeitos de fatores abióticos e da predação

Abstract

We sampled nine floodplain lakes in 2010, by two seasons of the hydrological cycle (rising water and receding water). The samplings were made by two spatial scales, the first one represented by the type of lake (coastal, island and terra firme) and second by the type of habitat (open water, macrophyte banks and flooded forest). We collected 18,783 individuals (1,406 kg) belonging 167 species. The order Characiformes and the family Characidae showed the highest species richness and abundance. Psectrogaster rutiloides and Pygocentrus nattereri were the most abundant. The terra firme lakes showed the highest richness, with 130 species, and coastal lake showed the highest abundance, by number of individuals caught (42%) and weight (38%). Flooded forest habitat and the receding water season showed the greatest occurrence of unique species, with 20 species. The structure of fish assemblages showed spatial pattern, distinguishing terra firme lakes from coastal and island lakes. The Analysis of Variance - ANOVA identified statistical difference about richness for habitat type, diversity and evenness for type of lake and type of habitat. The Analysis of Similarity – ANOSIM showed similarity (p>0.05) in the fish composition for the type of lake and type of habitat. The ANOVA with environment date showed pH, O2S and transparency were different between the types of lake. Depth was different between the habitats. The temperature was different by season and type of lake. The Canonical Correspondence Analysis - CCA showed that its first axe was structured by the type of lake and its second axe by the type of habitat. The richness and abundance of predators influenced the fish diversity of floodplain lakes. Transparency, depth and dissolved oxygen were determinant for the predators.