Abstract: Since Spartina alterniflora was transplanted on the Jiangsu coast in 1979, its rapid expansion has a great impact on the native coastal ecosystem. In Rudong, Fistulobalanus albicostatus provides a typical example of the influence by the expansion of Spartina alterniflora. In the present study, 28 quadrates along 5 tidal creeks were sampled during October 2012, to collect the above-ground parts of Spartina alterniflora plants and the barnacles attached to the plants. The maximum elevation at which barnacles attach to the plants were measured. Analyses of the samples reveal that the barnacles are distributed within a narrow zone, on average 5 m wide on both sides of the tidal creek; their landward extension is determined by the size of the tidal creek, i.e. a larger creek is associated with a longer extension. The maximum elevation at which barnacles attach to the plants shows the same level at different sites. Fistulobalanus albicostatus is the only barnacle species in the study area; its average biomass is 273±69 g·m^-2, and most barnacles have a diameter of 2~10 mm in the autumn. Biomass of Spartina alterniflora is 981±81 g·m^-2. Plants near the tidal creeks are tall and lower popularity density, while plants far away from the tidal creeks are undersized but higher popularity density. Correlation analysis indicates that although Spartina alterniflora provides the barnacles with an attachment base, its influence on the biomass and spatial distribution pattern is weak. The dominant factor of barnacle attachment-distribution is seawater inundation. The importance of the inundation time implies that the negative topography in relation to tidal creeks is beneficial to the attachment and survival of the barnacles. Meanwhile, higher velocity in tidal creek is advantageous for barnacle attachment, and flooding and ebbing tides in the creek will bring abundant food for barnacles.

Key words: Fistulobalanus albicostatus, Spartina alterniflora marsh, threshold of inundation time, tidal creeks, tidal flat morphology, Jiangsu coast