Effects of Spartina alterniflora invasion on macrobenthic faunal community in different habitats of a mangrove wetland in Zhanjiang, South China

Abstract

Mangroves are indispensable for maintaining biodiversity and human well-being in local or global, and their structure and functioning highly depend on the macrobenthos Although exotic cordgrass, Spartina alterniflora Loisel, is an increasing threat to the mangrove wetlands (including the associated unvegetated shoals) of China, its effects on the macrobenthic fauna in such wetlands is poorly understood. The macrobenthic faunal communities were compared in (1) an Avicennia marina monoculture vs. an S. alterniflora-invaded A. marina stand (a mixture of A. marina and S. alterniflora) and in (2) an unvegetated shoal vs. an S. alterniflora-invaded shoal that had rapidly become an S. alterniflora monoculture in Zhanjiang, China. The presence of S. alterniflora had little influence on indices of the macrobenthic faunal community in the A. marina monoculture, but significantly decreased the density and biomass of macrobenthic faunal community in the unvegetated shoal. The composition of the macrobenthic faunal community was more similar between the invaded and non-invaded A. marina stand than between the invaded and non-invaded unvegetated shoal. Compared the four habitats, the presence of vegetation significantly decreased the density and biomass of macrobenthic faunal community. Further analysis showed that differences in the macrobenthic faunal community between invaded and non-invaded habitats were associated with increases in the sediment organic matter content and plant density. These results indicate that the effects of S. alterniflora on the macrobenthic faunal community depend on habitat type of mangrove wetland is invaded, whereas additional research is needed to confirm and clarify these findings.