Salinity gradients shape the resilience of estuarine microbial ecosystems to extreme weather events

Extreme weather events are increasing pressure on coastal ecosystems and the biogeochemical services they sustain, but the factors shaping microbial resistance and recovery after typhoons remain unclear. Here we tracked bacterioplankton community dynamics across the Jinjiang River–Quanzhou Bay estuary before and after Typhoon Haikui and analysed seven additional storm-event datasets. Preexisting salinity gradients were strongly associated with poststorm community stability. Low-salinity riverine communities showed a prolonged compositional shift, expansion of fast-growing opportunistic taxa, and reduced co-occurrence network complexity. In contrast, high-salinity bay communities showed greater compositional resistance and faster apparent recovery, patterns consistent with stronger environmental filtering, rare-taxon responses, and more connected co-occurrence networks. A meta-analysis of additional storm-event datasets supported the broader relevance of this pattern. Together, these findings suggest that poststorm microbial recovery is temporally delayed and spatially heterogeneous, and that salinity gradients may help identify relatively stable and vulnerable zones in coastal ecosystems.