Importance of temporal variability at different spatial scales for diversity of floodplain aquatic communities

Summary Long‐term ecological data were used to evaluate diversity components of aquatic communities at different spatial scales in the Upper Paraná River floodplain. Diversity of aquatic macrophytes, fish and zooplankton communities were expected to vary in response to temporal variability in hydrological regime and associated environmental heterogeneity. Results support the importance of β‐diversity (diversity among sites within a floodplain) for γ‐diversity (regional diversity) at both small (e.g. lakes within a subsystem) and large spatial scales, such as subsystems comprised of a main river channel and associated lakes. Interestingly, diversity components for all groups exhibited low temporal variability, despite relatively high temporal variation in γ‐diversity. Temporal variability of diversity components and environmental variables were not correlated, indicating that the underlying ecological mechanisms driving diversity were not related to environmental variability of the floodplain. For management and conservation of floodplain communities our findings imply that efforts designed to preserve biodiversity and maximise environmental heterogeneity at a specific spatial scale should be effective, with conservation focused on maintaining spatial heterogeneity that promotes β‐diversity.