Abstract: Temporal and spatial variation of mollusc community structures (i.e. species composition and taxonomic diversity) in the intertidal zone of Yellow River Delta were explored in four flow path of Yellow River to the sea in autumn of 2018 and spring of 2019. A total of 45 species of mollusc were collected and identified to be from 24 families and 11 orders in 2 classes. Among them, Littorina brevicula, Umbonium costatum, Batillaria cumingi, and Nassarius concinnusc were dominant species. The annual average density and average biomass of molluscs were 411.56 ind·m^-2 and 222.25 g·m^-2, respectively. At four flow path to the sea, the Margalef richness index (d) value ranged from 0.329 to 1.648, the Pielou index (J) value ranged from 0.302 to 0.678, and the Shannon-Wiener index (H') value ranged from 0.298 to 1.384. The variance analysis indicates that only average biomass had significant interactions between locations and seasons (P<0.05). The annual average density, average biomass, richness index and diversity index had extremely significant difference among different locations (P<0.01), and the seasonal difference was not significant (P>0.05). The spatial distribution of molluscs was significantly affected by the change of flow path of Yellow River to the sea, which had a certain relationship with the water and sediment discharge regulation and ecological water dispatching project. The molluscs, as the main food source of migratory water birds, are vitally important to the protection of water birds, so that their monitoring and protection should be strengthened.

Key words: mollusc, biodiversity, intertidal zone, Yellow River Delta