Water-sediment regulation drives multi-taxon biodiversity and ecological network dynamics in the Yellow River Estuary

The Yellow River's high sediment load requires the Water-Sediment Regulation Scheme (WSRS) to manage sediment and water flow, leading to significant environmental changes and changes in biodiversity in the Yellow River Estuary (YRE). The present study used an environmental DNA approach to assess changes in biodiversity and community structure of invertebrates and fish in the YRE during WSRS. A total of 301 invertebrate species were identified using COI, and invertebrate communities remained stable from July to August 2022. Fish diversity declined significantly, with 14 detected species. Community stability analysis based COI revealed increased average degree and strong connections in invertebrates but reduced modularity in August, while the co-occurrence networks shifted from multiple modules (July) to a single dominant structure (August). Dominant species S. crassa abundance significantly declined from 24 % in July to 7 % in August (p < 0.05), but functioned as a bridging species in the invertebrate taxa. Redundancy analysis revealed significant shifts in invertebrate taxa between July and August (p = 0.001), driven by temperature, pH, dissolved oxygen, nitrate nitrogen, and ammonia nitrogen. Fish species were mainly influenced by suspended solids and phosphate. The results show that environmental factors have varying effects on different biological taxa in YRE. This study helps to better understand the impact of water-sediment regulation on the ecological structure and provides new insights for future ecological management in the YRE.