Abstract: An investigation was conducted in the summer of 2021 (pre-restoration) and summer 2022 (post-restoration) to evaluate the restoration effectiveness of replacing the invasive Spartina alterniflora with mangrove Kandelia obovata in a coastal wetland in Yueqing Bay. We compared macrobenthic community structure, diversity, stability, and their relationships with environmental variables among three habitat types: native mangroves, the S. alterniflora removal area, and bare mudflat. The results showed that: (1) A total of 36 macrobenthic species belonging to 5 phyla and 22 families were identified, with Mollusca accounting for 61.11% of the total number of species; (2) Following restoration, species richness and diversity indices in the S. alterniflora removal area increased, but remained lower than those in the native mangrove habitat, indicating that the community was still at an early stage of recovery; (3) Abundance-biomass comparison (ABC) curves showed only minor interannual changes in the abundance-biomass pattern in the S. alterniflora removal area, suggesting relatively balanced short-term community stability, whereas the bare mudflat exhibited high biomass (80.60 g·m^-2) but low stability; and (4) Combined stress from sediment heavy metals (Zn and Cu) and inorganic nitrogen in porewater significantly constrained community diversity (Mantel test, P<0.05). Overall, the replacement of S. alterniflora with K. obovata promoted the recovery of macrobenthic communities. However, stable and sustainable restoration outcomes will require effective pollution control and long-term monitoring.

Key words: mangrove, macrobenthos, community stability, plant replacement