外来植物互花米草（Spartina alterniflora）通过沉积食性螺类进入盐沼食物网：稳定同位素与脂肪酸分析

Whether exotic plants change the energy base for native consumers, altering the trophic structure and food web interactions, is controversial and system specific. The response of deposit-feeding animals to plant invasions is unclear because their food sources are difficult to identify. We examined the effect of the exotic plant species, Spartina alterniflora, on the food source of two dominant snail species, Assiminea latericea and Cerithidea largillierti, in Yangtze River estuary salt marsh using combined stable isotope and fatty acid analysis. We collected the snails and potential food material (sediment organic matter, particulate organic matter, and plant material) in S. alterniflora and native plant Phragmites australis habitats. Our results indicated that A. latericea and C. largillierti are deposit feeders grazing sedimentary particles originating from diatoms, bacteria, and vascular plants. The invasive species S. alterniflora did not result in a change in the relative contribution of microalgae, bacteria, and vascular plants to the food source of the snails. The invasive S. alterniflora was confirmed to be assimilated by both snail species. The higher assimilation of S. alterniflora by A. latericea compared with C. largillierti is probably related to the greater ability of A. latericea to assimilate plant materials. Overall, S. alterniflora was incorporated into the food web of the estuarine salt marsh by the dominant snail species with generalist-feeding habits.