Community Structure of Macrobenthos Inhabiting the Integrated Offshore Wind Power and Marine Ranching Area of Laizhou Bay, China, and Assessment of Its Ecological Quality

To investigate the community structure of macrobenthos inhabiting an area integrating offshore wind farms and marine ranching and assess its benthic ecological quality, four seasonal surveys were conducted in January (winter), April (spring), July (summer), and October (autumn), 2024. The study was carried out in Laizhou Bay, covering three fields, the wind-reef (wind power foundation with artificial reefs), the wind foundation (wind power foundation without artificial reefs), and the blank control (without wind power foundations and artificial reefs). A total of 120 macrobenthic species were collected, which included 94 in the wind-reef field, 79 in the wind foundation field, and 63 in the blank control field. Polychaetes accounted for the highest (the dominant, 48.15%), representing the leading taxonomic group within the community. The overall abundance and biomass of macrobenthos peaked in autumn and troughed in spring. Annual average abundance and biomass trended as the wind-reef field (340.89 ind/m², 12.27 g/m²)> the wind foundation field (284.82 ind/m², 10.86 g/m²)> the blank control (275.41 ind/m², 10.27 g/m²). Cluster and principal coordinates analyses (PCoA) revealed that seasonal variation in community structure was more pronounced than spatial differences among fields. SIMPER analysis identified species such as Micronephthys oligobranchia, Nephtys ciliata, and Phyllophorus ordinata as the primary contributors to community differences across seasons and fields, along with other species that collectively influenced the observed variations. ABC curve analysis showed that biomass curves consistently remained above abundance curves, indicating that the macrobenthic communities were not significantly disturbed. The AZTI's marine biotic index (AMBI) for macrobenthos ranged from 0.12 to 3.72, with the macrobenthic community in the study area generally experiencing light seasonal disturbance. The M-AMBI index for macrobenthos ranged from 0.33 to 0.91. Overall, the benthic ecosystem in the study area is at a relatively good status.