Beta diversity can explain the changes inman species composition on the spatial and temporal scales, which is a hot issue in the field of biodiversity research. However, the patterns and drivers of the beta diversity in mangrove ecosystems are still unclear, especially in mangrove macrobenthic ecosystems in China, and their underlying processes were understudied. To explore the patterns and driving factors of beta diversity of macrobenthos, and reveal the underlying processes of community assembly, we investigated macrobenthic community composition in individual mangroves in Yanpu Bay, Aojiang Estuary, Oujiang Estuary, and Ximen Island mangroves, which located in the northern margin of China. This study used Baselga’s approach of beta diversity partitioning based on the Sørensen dissimilarity index, and decomposed beta diversity into turnover and nestedness components to better understand the patterns behind beta diversity. We sampled the macrobenthic organisms and corresponding environmental data (e.g., water temperature, salinity, dissolved oxygen, sediment factors) and latitude data about four mangroves that are in the northern margin of China. We calculated the beta diversity of macrobenthic communities and quantified the relative contributions of turnover and nestedness to beta diversity. In addition, the Mantel test and multiple regression on distance matrices (MRM) analysis and variation partitioning analysis (VPA) were employed to determine the effect of environmental variables and spatial distance on beta diversity and its components of macrobenthic communities. These methods further revealed the role of environmental filtering and dispersal limitation in community assembly. The results showed that ① There were significant differences in species composition of macrobenthos among different mangroves (P<0.01). The contribution of mangrove turnover components to beta diversity increased with increasing latitude, and it dominated the community beta diversity, indicating that they were caused by the replacement of species in space or between communities. ② The beta diversity increased with the increase of spatial geographical distance, and the similarity of species composition showed an obvious distance attenuation pattern (Mantel test: P<0.05), it means that the dispersal limitation affected the species composition of the community. ③ Multiple regression on distance matrices (MRM) analysis showed that sediment silt content is a key environmental factor driving beta diversity of macrobenthic communities. Moreover, the results also indicate that environmental filtration and dispersal limitation played important roles in the community assembly process.

This study demonstrates that environmental and spatial factors jointly drive the patterns of beta diversity of macrobenthos communities in mangroves, and environmental filtering and dispersal limitation are important regulatory mechanisms in the process of community assembly. In addition, this study can lay a theoretical foundation for the formation and maintenance mechanism of species diversity of mangrove macrobenthos community in the northern margin of China.