Flood‐Mediated Hydrological Connectivity Is Associated With Water Quality and Eutrophication Risk in the Lake Poyang Basin

Hydrological connectivity is closely associated with water quality in floodplain lake systems, yet its relationship with nutrient levels and differences between wet and dry seasons across lake networks remains insufficiently assessed. This study investigated 35 peripheral lakes surrounding Lake Poyang under three hydrological connectivity regimes: year‐round connection, wet‐season connection and no connection. Field surveys during the wet and dry seasons of 2024 evaluated nutrients, hydrochemical characteristics and chlorophyll‐a (Chl‐a) as an indicator of algal biomass. Hydrological connectivity and season were both significantly associated with multivariate water quality conditions, whereas their interaction was not significant. Unconnected lakes had the highest total nitrogen (TN), total phosphorus (TP) and Chl‐a concentrations, indicating comparatively greater eutrophication risk. Wet‐season connected lakes showed comparatively low dissolved nutrient concentrations during the survey under high water conditions, while year‐round connected lakes generally had lower nutrient and Chl‐a concentrations than unconnected lakes. Although individual variables showed different patterns between wet and dry seasons among connectivity regimes, the overall multivariate seasonal response did not differ significantly among regimes. Overall, hydrological connectivity was associated primarily with differences in water quality conditions and nutrient accumulation under the hydrological conditions observed in 2024. These findings provide a basis for differentiated monitoring and further evaluation of management related to hydrological connectivity.