Abstract: To gain a deeper understanding of the diversity and driving mechanisms of macrobenthic communities in Nansi Lake of Shandong Province, we conducted benthic surveys at 10 sampling sites in July and November 2024. We analyzed the β-diversity of macrobenthic communities and its turnover and nestedness components by using the Baselga method. We further explored the effects of multiple environmental factors and spatial distance among sites by Mantel analysis to reveal the roles of environmental filtering and dispersal limitation in driving β-diversity patterns of macrobenthic communities, and analyzed the contributions of sampling sites and species to β-diversity by the Legendre method. The results showed that the overall β-diversity of macrobenthic communities in Nansi Lake was higher in summer (0.88) than in autumn (0.83). Turnover components contributed more to β-diversity than nestedness components in both seasons, accounting for 94.3% and 89.2% of the total β-diversity, respectively. At the station level, the turnover component generally contributed more to β-diversity than the nestedness component. The partial Mantel test revealed that β-diversity in summer showed no significant correlation with environmental factors and spatial distance, while that in autumn was significantly positively correlated with spatial distance, indicating that dispersal limitation played an important role in shaping autumn β-diversity patterns. Legendre analysis indicated that sampling sites S1, S9, and S10 contributed significantly to β-diversity indices in both seasons. In summer, β-diversity was mainly driven by key species, including Procladius sp., Bellamya sp., Polypedilum sp., and Microchironomus sp., while in autumn, the contributions of Procladius sp., Alocinma longicornis, and Glyptotendipes sp. were more prominent. Redundancy analysis showed that key species abundance was mainly influenced by total phosphorus, transparency and permanganate index in summer, and that conductivity and dissolved oxygen were the main environmental factors affecting key species abundance in autumn.

Key words: macrobenthos, beta diversity, seasonal change, driving factor, Nansi Lake