Abstract: Spartina alterniflora is a typical invasive species in the coastal zone of China. The removal of S. alterniflora has become a major national ecological restoration mission. The combination of mowing and ploughing is one of the main methods of S. alterniflora eradication. To evaluate the effect of this method on the macrobenthos in coastal salt marsh, we investigated the macrobenthos and sediment physicochemical indices of 12 sampling sites in September to December of 2021-2022, before and after the physical control of S. alterniflora in the ecological restoration project of Nanhui tidal flat. The results showed that 22 species of macrobenthos belonging to 3 phyla, 5 classes, 12 orders, and 19 families were identified during the two years. After the project, species number, density, biomass, Shannon diversity index and Chao1 index of macrobenthos significantly increased. In terms of macrobenthos community, the proportions of Polychaeta, Bivalvia and Malacostraca all increased, but the proportions of Gastropoda and Insecta showed a decreasing trend. The results of non-metric multidimensional scaling (NMDS) and analysis of similarities (Anosim) indicated that community structure of macrobenthos was significantly different before and after the project, and that dominant species changed from Assiminea latericea, Cerithideopsis largillierti and Notomastus latericeus to Assiminea sp., Assiminea latericea, Notomastus latericeus, Glauconome chinensis and Cerithideopsis largillierti. The results of redundancy analysis (RDA) indicated that physicochemical factors such as sediment salinity, water moisture changed after the project, which affected the community structure of macrobenthos.

Key words: Spartina alterniflora, ecological restoration, macrobenthos, sediment physicochemical factor