Community structure of benthic macroinvertebrates in reclaimed and natural tidal flats of the Yangtze River estuary

Previous studies have found differences between communities of benthic macroinvertebrates living in constructed tidal flats compared with natural ones. We analyzed the distributional characteristics of benthic macroinvertebrates in a blowing sand reclamation area (Area A), a dike-building silting area (Area B), an out-of-siltation area (Area C), and a natural tidal flat (Area D) in order to characterize the community structure and diversity of benthic macroinvertebrates in a human-disturbed estuarine tidal-flat wetland. A total of 32 benthic macroinvertebrate species were identified (Area A = 7; Area B = 12; Area C = 10; Area D = 27). The diversity index was variable where: Area B < Area C < Area A < Area D. A higher average annual abundance of benthic macroinvertebrates was found at Area B (840.43 ± 569.23) ind/m2 than in Area D (203.00 ± 5.85) ind/m2, Area A (42.87 ± 10.21) ind/m2, and Area C (17.64 ± 1.50) ind/m2. The biomass in Area C (3.18 ± 0.39) g/m2 was lower than in the other areas. One-Way ANOVAs detected significant differences (P< 0.05) in the abundance and biomass within Area B among seasons; however, there were no significant seasonal differences (P > 0.05) in the abundance and biomass of Areas A, C, and D. An abundance/biomass curve showed that the habitat in Areas A, B, and C could be categorized as moderately disturbed, whereas Area D was categorized as undisturbed. The results of cluster analysis suggested distinct assemblages in the four sampling areas. Reclamation raised the altitude of tidal flats, weakening the tidal power and changing the physical and chemical parameters of the water, leading to a change in the community structure of benthic macroinvertebrates. Keywords: Reclamation area, Tidal flat, Benthic macroinvertebrates, Community structure