Macrobenthic diversity in protected, disturbed, and newly formed intertidal wetlands of a subtropical estuary in China

•Biodiversity in five intertidal wetlands of Yangtze estuary was assessed.•Diversity differences among protected, disturbed, and new wetlands were analyzed.•Nature reserves were unique in positive succession of biodiversity.•Degradation in diversity and ecological health occurred in heavy reclamation zone.•Evolution process of macrobenthic community was slow in the newly formed wetland. In this study, intertidal macrobenthic diversity in protected, disturbed, and newly formed wetlands of Yangtze estuary was assessed using PRIMER 5.2 based on species diversity and species relatedness. We observed high diversity in nature reserves and low diversity in adjacent disturbed and newly formed wetlands. These diversity data were then integrated with historical data to detect the variation in macrobenthic diversity over the past two decades. The integrated data indicated that the intertidal macrobenthic diversity sharply decreased in heavy reclamation tidal flats whereas markedly increased in non-disturbed nature reserve and newly formed wetland. Benthic health was observed with the departure degree of average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) from the simulated 95% confidence funnel. All the habitats were subjected to different levels of human interference, except Jiuduansha and Beigangbeisha. The degradation of intertidal wetland in Yangtze estuary was mainly attributed to land reclamation, overgrazing, and overfishing.