Persistence and stability of cichlid assemblages in neotropical floodplain lagoons

In this study, we evaluated how cichlid assemblages are affected by seasonal and interannual variations in water volume in the floodplain lagoons of the Cuiaba River in the Pantanal wetland. Eleven lagoons were sampled in the early dry season and the early rainy season over a three-year period. Analysis of similarity (ANOSIM) showed that the species compositions and relative abundances were distinct between the seasons, which indicates that neither persistence nor stability was maintained on a seasonal basis. However, the interannual comparisons show the opposite tendency, indicating strong stability and persistence on an annual basis. These results indicate that the cichlid assemblages in these lagoons have two equilibrium points, one in the early dry season and the other in the early rainy season, and that the assemblages alternate between these points through the hydrologic cycle. In addition to the effect of the water level variation, the abundance distribution is also affected by conductivity and pH, which also influence the total abundance of the species in the assemblage.