Macrobenthic community structure of Rudong coastal wetland, China: the impact of invasive Spartina alterniflora and its implication for migratory bird conservation

Spartina alterniflora is an invasive plant whose effects on macrobenthic communities are still unclear. The Rudong coast has been invaded by S. alterniflora for years. The effects of S. alterniflora on the macrobenthic community structure have rarely been investigated along the Rudong coast. As the Rudong coastal wetland is an important staging site for migratory birds along the East Asian-Australasian Flyway, an alteration in its macrobenthic community structure may have implications for the conservation of coastal wetland birds and rare waterbirds along that flyway, since macrobenthos are a major food source for these migratory birds. We conducted a survey in the Rudong coastal wetland to compare the macrobenthic community structure and sediment properties between a S. alterniflora-invaded area and a bare mud flat. The results showed that there was no significant difference in the biomass, abundance, species number or biodiversity between the invaded area and the mud flat. However, there were significantly higher heavy metal concentrations in the invaded area, and the community structure was obviously altered. The dominant Mactra veneriformis in the bare mud flat was replaced by another surface-feeding bivalve, Laternula anatina, in the invaded area. Our study suggested that the growth stage of the plants might be an important factor when assessing the impact of S. alterniflora on the macrobenthic community structure. Short and sparse S. alterniflora plants altered the benthic environment and species composition but did not necessarily reduce the biodiversity, abundance or biomass of macrobenthos. The dominant bivalve (L. anatina) living in the sparsely vegetated area was abundant, small, and soft-shelled, which might make it a better food source for the birds than the hard-shelled bivalve (M. veneriformis). Thus, S. alterniflora cannot be simply classified as a threatening factor to the Rudong coastal wetland ecosystem, and its advantages must also be considered.

Automated summary

We conducted a survey comparing the macrobenthic community structure and sediment properties between an invaded area and a bare mud flat. The results showed no significant difference in biomass, abundance, species number, or biodiversity between the invaded area and the mud flat. However, higher heavy metal concentrations and altered community structure were observed in the invaded area. The growth stage of S. alterniflora might be an important factor when assessing its impact on the macrobenthic community structure.