Abstract: The β diversity of biological communities, as an important hub connecting local (α) diversity and regional (γ) diversity, has always been a research hotspot in ecology in terms of its spatial pattern and construction mechanism. However, the research in Marine macrobenthos communities is still relatively weak.This research is grounded in the survey data of macrobenthos in the northern Beibu Gulf in August 2024. The β-diversity decomposition method proposed by Baselga, which is based on the Sørensen index, was employed to partition it into the sum of turnover and nestedness components. Moreover, the β-diversity decomposition method put forward by Legendre et al. was utilized to decompose it into the contributions of individual stations (LCBD) and individual species (SCBD) to the overall β-diversity.On this basis, by applying correlation analysis and canonical correspondence analysis, the relationships between the β diversity of macrobenthos in the Beibu Gulf and their LCBD and SCBD indices and species richness and environmental factors were systematically explored. With the aim of comprehensively revealing the β diversity pattern and its driving factors. The results show that: (1) A total of 73 species of macrobenthos were recorded in the Beibu Gulf, belonging to 9 phyla, 16 classes, 32 orders, 52 families and 63 genera. Among them, the dominant species composition was polychaete annelids, followed by crustaceans, echinoderms and mollusks; (2) The β diversity level of the macrobenthic species composition in this area is relatively high. At all stations, the cycling components are dominant, indicating that there is significant spatial heterogeneity in the composition of macrobenthic species in the study area; (3) The maximum value of SCBD is contributed by the amphipod Amphioplus depressus (0.095), while the echinoderms and annelids have larger SCBD values; (4) The maximum value of LCBD is contributed by the stations with high contents of total nitrogen, total carbon, and organic carbon (0.057) at the S02-3 site. The stations with larger contributions are mainly distributed in the coastal area of the Beibu Gulf. The LCBD value is negatively correlated with species richness (R² = 0.018); (5) TC, pH and water depth are the three main environmental variables that significantly affect the macrobenthos community. In summary, the results of this study reveal the β diversity pattern of macrobenthos in the northern part of the Beibu Gulf and its driving factors, providing a scientific reference for regional biodiversity conservation and management.

Key words: Beibu Gulf, macrobenthic, beta diversity, species contributions to beta diversity, local contributions to beta diversity