Abstract: The hard substrate introduced by offshore wind turbine foundations creates new habitats for sessile organisms. Understanding sessile community structure on wind piles is essential for evaluating the ecological impact of offshore wind farm construction. We analyzed the vertical distribution of sessile communities on wind piles using multivariate statistical methods based on sampling conducted in July 2023 at depths of 0, 5, 10, 15, and 20 m across four wind pile stations at the Zhuanghe Offshore Wind Farm in the North Yellow Sea. A total of 49 sessile species were recorded, with arthropods (17 species) as the most abundant. The dominant species on wind pile surfaces were Hiatella orientalis, Mytilus galloprovincialis, and Crassostrea gigas. The biomass (980.3-3118.8 g·m^-2) and abundance (1970.7-4706.7 ind·m^-2) of sessile organisms, as well as the Margalef index, Pielou index and Shannon index showed depth gradients. Cluster analysis revealed that the surface layer dominated by barnacles and M. galloprovincialis, and the deeper layers characterized by mobile benthic species such as polychaetes, small bivalves, and crustaceans. The results of ABC curve, AMBI, and M-AMBI analyses showed that after 2-3 years of wind pile construction, the surface sessile organism was less stable, while the submerged sessile organism was relatively stable. The results could provide references for the ecological evaluation of offshore wind farms and the prevention and control of fouling caused by sessile organisms.

Key words: offshore wind farm, North Yellow Sea, sessile organism, community structure analysis, biodiversity