Implicações de macrófitas invasoras na planície de inundação do alto rio Paraná sobre a estrutura da comunidade perifítica.

Abstract

In the floodplain of the upper Paraná River, the occurrence of Hydrilla verticillata (L. f.) Royle and Egeria najas Planch has become dominant. Until then, Eichhornia azurea Kunth was the most important and dominant substrate. Thus, it is believed that the proliferation and abundance of submerged macrophytes altered the species composition, richness and abundance of epiphytic algae in both lentic and lotic environments, and on the substrate E. azurea. Thus, it was necessary to understand the likely changes in the structure and dynamics of periphytic community, an important primary producer and the base of the trophic web of these ecosystems. Sampling was conducted quarterly in 2009, was used as substrate petioles of emergent macrophyte Eichhornia azurea and parts of submerged macrophyte Egeria najas. In 2000, samples were collected from petioles of E. azurea, using the same methodology in 2009. Initially, we analyzed the richness, density and diversity of epiphytic algae on macrophytes morphologically different in a lentic environment (Lake Pombas) located in the floodplain of the upper Paraná River, and later, described and compared the composition of periphytic algae in 2000 (no submerged macrophytes) and 2009 (the abundant presence of these macrophytes) in lentic and lotic environment of the floodplain of the upper Paraná River. The results suggest that the hydrological dynamics of the floodplain is the controlling factor directly on the community structure of epiphytic algae, and the heterogeneity of the substrate an indirect controlling factor, and the increase was also observed loosely bonded species between the years 2000 and 2009, due to the proliferation of submersed, that these changes are more pronounced in low water period, especially for the lotic environment.