INTER-ANNUAL VARIATION OF OSTRACOD (CRUSTACEA) COMMUNITIES IN THE UPPER PARANÁ RIVER FLOODPLAIN, BRAZIL

Riverine floodplains have a large environmental heterogeneity, with lentic and lotic environments and a variety of aquatic macrophytes, providing habitat for various aquatic and terrestrial organisms. Here, we evaluate species composition and beta diversity of ostracod communities over a period of 14 years in two permanently connected lakes (Patos and Guaraná) and two rivers (Ivinhema and Baía) of the Upper Paraná River floodplain. We predict that the ostracod species composition differs in both types of environments amongst the years, and that beta diversity changes over time. Thirty-eight ostracod species were recorded, including new taxa that remain to be described. The change in ostracod species composition over time may be a result of natural or anthropogenic events occurring in the floodplain, in addition to the influence of local abiotic factors. The sequence of floods and droughts might also explain the difference in the contribution of replacement (turnover) and richness difference (loss or gain) components over time. These results show the importance of long-term research to understand the temporal dynamics of the communities, mainly in dam-regulated floodplains