Variação espacial e temporal em peixes com estratégias similares : explorando padrões em guildas reprodutivas de uma planície de inundação.

Abstract

The seasonal flooding regime is the most important structuring force determining community structure and functioning of floodplains, providing great spatiotemporal heterogeneity of habitats and high biological diversity. The magnitude of dependence for fish species reproduction to this environmental seasonality is associated with the high variation in reproductive patterns, which can hamper the study of these communities. Thus, a classification in ecological reproductive guilds is a great alternative, since it reduces a large number of species in a few groups with similar responses within. We tested the hypothesis that fish reproductive guilds from the upper Paraná river floodplain exhibit spatial and seasonal distribution. Samples were taken quarterly in 2010 from 20 sampling stations, which represents the several biotopes and subsystems of the floodplain. Fish species were categorized into four reproductive guilds. The PERMANOVAs performed indicate that the guilds presented spatial structure, possibly due to the influence of limnological and hydrological characteristics of the environments and species dispersion that may act in structuring fish assemblages. Baía and Ivinhema subsystems were more similar between them (NMS) when compared to the Paraná, demonstrating the negative effects of the dams built in this river on fish assemblages. It was also observed seasonal structure of the guilds; in the flood season (March) and in December the guilds had similar abundances and species richness among biotopes and subsystems (factors). In the other months, there was difference of these metrics in one or another factor. Thus, the seasonal flood promotes biotic homogenization and the local characteristics of environments of the floodplain habitats have influence in structuring fish assemblages of the upper Paraná river floodplain.