Responses of macrobenthic communities to artificial seawalls and coastal ecological restoration in the intertidal zone of Yueqing Bay, China

Human activities have caused considerable ecological losses, and while large-scale restoration efforts have already been initiated, the ecological effectiveness of these coastal artificial measures and projects remains unclear. To elucidate the ecological impacts of artificial seawalls and coastal ecological restoration, this study quantified macrobenthic biodiversity across six representative intertidal habitats — natural rock reefs, artificial seawalls, bare tidal flats (in the middle and low intertidal zones), Spartina alterniflora marshes, and restored tidal flats (following S. alterniflora removal) — in Yueqing Bay, China, during May and October 2024. Intuitively, natural rock reefs supported greater abundance, biomass, and diversity than artificial seawalls. Compared to bare tidal flats, transplantation mangroves exhibited higher biomass but lower species richness and diversity, and restored tidal flats showed seasonally increased species richness but decreased diversity. Additionally, no significant differences in macrobenthic communities were observed between artificial seawalls and natural rock reef or between bare and restored tidal flats, suggesting that variations were primarily reflected in species diversity rather than shifts in dominant species or compositional structure. In contrast, the community structure in transplantation mangroves differed significantly from that in other habitats. Overall, the negative effects on macrobenthic diversity of artificial seawalls in the high intertidal zone and positive signals from coastal ecological restoration in the middle intertidal zone are evident. Given the expanding scale of artificial constructions and coastal ecological restoration in intertidal zones, continuous ecological monitoring is essential to ensure sustainable development. • Assessed macrobenthic biodiversity across six intertidal habitats to evaluate the ecological effects of artificial seawalls and coastal ecological restoration (i.e. transplantation mangroves and Spartina alterniflor a eradication). • Natural rock reefs supported higher abundance, biomass, and diversity than artificial seawalls. • Transplantation mangroves had higher biomass but lower species richness and diversity than bare tidal flats. • Compared to bare tidal flats, restored tidal flats showed seasonal increases in species richness but decreases in diversity. • Continuous ecological monitoring is required to ensure sustainable development under expanding artificial constructions and coastal ecological restoration.