The effect of Spartina alterniflora eradication on waterbirds and benthic organisms

There has been an increasing number of coastal restoration projects to eradicate Smooth cordgrass (Spartina alterniflora) and restore bare tidal flats to conserve waterbirds. However, the evidence for the assumed benefits to waterbirds and benthic organisms after such restoration efforts remains limited. We evaluated the impact of S. alterniflora eradication on waterbirds and benthic organisms in southern China. We deployed time-lapse cameras and satellite trackers to quantify and compare the occurrence frequency and habitat use of birds in different habitats. We compared the density and biomass of benthic organisms collected in bare tidal flats and areas where S. alterniflora had been eradicated. We found that almost all waterbirds, except gulls, avoided areas where S. alterniflora was present. Once S. alterniflora was eradicated, the species richness and species-level diversity of shorebirds and waterbirds did not differ significantly from those of the bare tidal flats. At least 9 out of 14 tracked individual shorebirds used areas where S. alterniflora had been eradicated, with Common Redshank (Tringa totanus) demonstrating a clear preference for such habitat. The density and biomass of benthos in deeper sediments (5-20 cm below the surface) were significantly lower in areas where S. alterniflora had been eradicated than in bare tidal flats, indicating that the food resources for birds may take longer than 1 year to recover. This research demonstrates that the eradication of S. alterniflora is important for the restoration of waterbird habitats, and such efforts should be made in areas that are important to waterbirds.