Effects of mangrove wetland restoration on macrobenthos communities in the Pearl River Estuary Delta, China

Mangrove wetland restoration projects have been conducted for many years and it is important to evaluate their success. In this study, we explored the role of monitoring macrobenthos in assessing the success of mangrove restoration. In particular, we sampled soil and macrobenthos from a mangrove wetland area after restoration for one, three, and five years in the Pearl River Estuary Delta in China to explore the effects of different restoration periods on the macrobenthos community structure. The results showed that the macrobenthos collected in the study area mainly comprised Polychaete annelids and Bivalvia mollusks, and there were no significant differences in the species, biomass, richness index, diversity index, and evenness index among different mangrove wetland restoration stages. The macrobenthos biomass, species richness, diversity index, and evenness index were mainly correlated with the soil electrical conductivity, pH, total phosphorus, and soil organic carbon. Compared with mangrove restoration for one year, the average species richness, Margalef richness index, Shannon diversity index, and Pielou evenness index for macrobenthos were significantly higher after three years, thereby indicating that the macrobenthos species diversity increased significantly after mangrove wetland restoration for three years. However, the macrobenthos diversity was lower after mangrove wetland restoration for five years, which may have been due to human activities and soil pollution. The findings obtained in this study provide basic information to facilitate mangrove wetland restoration and conservation.