Inland wetlands of arid and semiarid regions are unique ecosystems shaped by pronounced salinity gradients that strongly regulate biodiversity patterns. However, comparative studies of multiple aquatic taxa along the salinity gradient remain limited. To disentangle taxon-specific responses, we surveyed aquatic invertebrates and zooplankton across 48 wetlands in the western Songnen Plain, Northeast China. Diversity patterns deviated from the "intermediate disturbance" hypothesis: Both groups declined with increasing salinity, with zooplankton showing greater diversity differences among salinity types than aquatic invertebrates. Indicator species analysis revealed strong taxon-specific responses: Sensitive taxa dominated freshwater wetlands, while hypersaline wetlands were characterized by a few highly tolerant species, confirming distinct salinity-dependent filtering. Elevated salinity reduced ecological network complexity, underscoring its destabilizing effects on community interactions. These results highlight distinct strategies of aquatic assemblages under salinity stress, demonstrate the value of multitaxon approaches for bioindication, and call for reevaluating saline-alkaline wetlands as a distinct ecosystem type requiring tailored, nature-based restoration strategies beyond conventional freshwater frameworks.