Changes in the Community Structure and Diet of Benthic Macrofauna in Invasive Spartina alterniflora Wetlands Following Restoration with Native Mangroves

The community structure and diet of benthic macrofauna in a Spartina alterniflora wetland and restored native Kandelia obovata mangrove forests of different ages were compared in Zhangjiangkou estuary, China. The biodiversity and total density of benthic macrofauna did not change after the restoration of Spartina wetlands with native mangrove species. However, the total biomass decreased significantly approximately half a year after physical treatments. This decrease in total biomass resulted from a change in the dominant gastropod from the larger Cerithidea djariensis to the smaller Assimine abrevicula. Gastropod and crab species in the Spartina wetland derived more than 80 % of their organic carbon from Spartina. Preliminary physical treatment and plantings of K. obovata did not change the diets of benthic macrofauna during year one of the restoration, but delta C-13 values in gastropod and crab species collected in both 10- and 40-year K. obovata forests were more depleted than those measured in the Spartina wetland, indicating a change in the diet of benthic macrofauna from homogenous to heterogeneous. These results suggest that biological replacement using native mangrove species can not only successfully control the spread of invasive Spartina, but also restore the diverse food web typical of a mature mangrove ecosystem.