Habitat change driven by plant invasion restructures benthic diversity in intertidal wetlands

Since its introduction to China in 1979, Spartina alterniflora has steadily expanded along the southeast coast of China and reshaped the intertidal ecosystem by altering the properties of sediments. These changes, in turn, will affect the composition and diversity of benthic communities. To explain the response of benthic faunas to this habitat change, we conducted a seasonal survey of three habitats in the Tiaozini in Jiangsu Province, which is an important stopover on the East Asian–Australasian Flyway. The study sites exhibit three gradients of invasion: S. alterniflora colonized zone, mudflat– S. alterniflora transition zone, and mudflat zone. We assessed alpha and beta diversity patterns of benthic communities in each zone and examined how key species were associated with sediment physicochemical properties. The results indicated that the invasion of S. alterniflora led to a decrease in alpha diversity and significant changes in community composition. The Beta diversity patterns were primarily shaped by species turnover. The changes in the properties of sediments, such as the increase in organic matter content and the expansion of grain size, are closely related to the changes in these benthic communities. These new habitats seem to favor species like Cerithidea largillierti and exclude others, including Diastylis tricincta and Terebra taylori . Overall, our study highlights the profound impact of S. alterniflora on intertidal benthic communities and reveals how invasive species alter food webs and ecosystem functions, which may have significant implications for waterbirds and other species dependent on benthic prey. • Spartina alterniflora invasion enriches organic carbon and nitrogen while reducing sediment grain size. • Sediment changes drive species turnover that dominates beta diversity in both spring and autumn. • Spartina alterniflora invasion may alter food webs and ecosystem functions, with potential effects on benthic fauna linked to waterbirds.