Annual and non‐annual fish assemblages respond differently to environmental and spatiotemporal variations of temporary wetlands from southern Brazil

Abstract

Abstract The fish community of temporary wetlands is highly dynamic due to the marked seasonal changes in hydrological and limnological conditions. In this study, we evaluated spatiotemporal variation in the fish community and the influence of environmental factors on this variation in temporary wetlands in southern Brazil. Two different life cycles—annual and non‐annual fishes—were recorded among species. Variation in the fish community appeared to be associated with differences in the life history strategy of species. While species of annual fish were present throughout the hydroperiod, gradually decreasing in density over time, non‐annual fish species had an opposite pattern, with higher densities in the final phase of the hydrological cycle. Variations in the composition and abundance of fish community in temporary wetlands were related to habitat and landscape attributes (area, number of microhabitats and isolation between temporary wetlands) and climate indicators of water availability (air temperature, average rainfall, and water level of the São Gonçalo channel), but not to water conditions (dissolved oxygen, pH, conductivity and water temperature). We concluded that the ichthyofauna of temporary wetlands are composed both of rare species, highly specialised for life within these ephemeral environments, and widespread generalist species that reach the wetlands opportunistically for short periods. Habitat and landscape attributes and changes in climate and hydrological variables over the hydroperiod are the factors that had the greatest influence on spatiotemporal variation of the fish community. Maintaining physical characteristics and the hydrological cycle of temporary wetlands is critical for the conservation of fish species inhabiting these vulnerable environments in southern Brazil. Habitat and landscape attributes and climate and hydrology fluctuations affect the annual and non‐annual fishes inhabiting temporary wetlands differently.