Connectivity of fish communities in a tropical floodplain river system and predicted impacts of potential new dams

Longitudinal and lateral connectivity is important for mobile aquatic species in rivers reproductive migrations, recruitment, gene flow access to food resources across habitat types. Water resource developments such as dams levees may disrupt these connections, causing river fragmentation loss of highly productive habitats floodplain wetlands. We used sulfur stable isotopes a tracer estimate patterns fish movement an unregulated tropical northern Australia, taking advantage observed spatial variation isotope values their the catchment. also modelled barrier related impacts potential dam development scenarios on movement. Fish with significantly different from local prey were determined be migrants. In ‘no dams’ scenario, varied among (0–44% migrant within where n > 5) sites (0–40% 5), immigration was higher more connected sites. Impacts water between scenarios, predictions that main channel Mitchell River would have highest impact three individual scenarios. This study provides critical information how flow-mediated supports community system. The generic quantitative approach combining tracers modelling powerful predictive tool. While we movement, our can other otoliths acoustic telemetry, making it widely applicable guide sustainable systems.