Effect of the exotic plant Spartina alterniflora on macrobenthos communities in salt marshes of the Yangtze River Estuary, China

The Yangtze River Estuary is an important eco-region of China; it has, however, been heavily infested with the invasive plant Spartina alterniflora. This study examined the benthic communities associated with the invasive S. alterniflora and two native plants (Scirpus mariqueter and Phragmites australis) at three tidal elevations to provide a comprehensive evaluation of the impacts of marsh plant invasions on intertidal macrofauna of the Yangtze River Estuary. Spartina alterniflora had significantly sparser and taller stems than S. mariqueter, whereas the traits of S. alterniflora and P. australis were relatively similar. A total of 23 macrofaunal taxa were recorded during this study and their mean density was 1885 ind. m−2. Numerically, gastropods and bivalves were the dominant group; together they constituted 95.72% of the total macrofaunal individuals. The differences in macrofaunal community structure were greater among different elevations than between native and exotic plants. The effects of plant types on species richness and densities of macroinvertebrates were generally weak. Densities of only one species (Glaucomya chinensis) differed significantly between S. alterniflora and S. mariqueter marshes at the lower elevation. The tolerance of the macrobenthos to plant invasions thus depends on various factors, including habitats, species of macrofauna, and local plants.