Invasive cordgrass facilitates epifaunal communities in a Chinese marsh

Structural aspects of the environment frequently influence the taxonomic and functional diversity of associated ecological communities. Spartina alterniflora and Phragmites australis both are structure-forming species in salt marshes but reciprocal invaders. Epifaunal communities on invasive Phragmites on the east coast of North America are reduced relative to native Spartina. But, the impacts of invasive Spartina on epiphytic communities in Phragmites dominated marshes in the Western Pacific are unknown. We examined epifauna on live and dead stems of invasive S. alterniflora and native P. australis in the Yangtze River estuary in China. Epiphytic invertebrate abundance on S. alterniflora was similar to 5x greater than on P. australis, suggesting that S. alterniflora supports more abundant epiphytic communities than P. australis, irrespective of region. For both live and dead stems, most epifaunal groups, including Namatoda, Copepoda, Halacarida and Oligochaeta, were more abundant on S. alterniflora than P. australis. Enhanced epifaunal abundance could benefit the nursery function of marshes by increasing secondary production. Dead S. alterniflora were the best habitat for nematodes, especially bacterivores and fungivores. This suggests that differences in litter quality may be important in these nematode communities and that more active biological processes may occur on Spartina influencing nutrient cycling rates.