| Macrobenthos is an essential biological group of wetland and marine ecosystems and they have a broad distribution in the benthic area. The succession of their community can reflect the health condition of the ecosystem. This paper discuss the influence of enclosing project on species distribution and community organization feature of macrobenthos and disturbance conditions of different enclosing methods to ecological environment of wetland. Meanwhile, the macrobenthos has been divided into different functional groups to reveal spatial and temporal distribution of reclamation and natural tidal flats as well as the influence of enclosing project to the macrobenthos functional groups. On the basis of above research, this paper has thoroughly studied the characteristics of community structure and standing crop of macrobenthos for evaluating achievement of Artificial Oyster Reef project(North and South Guide Dikes), hoping to supply theory evidence of rehabilitation and reconstruction of oyster reef and renovation of ecosystem structure and function.The main research conclusions are the following:1. Influence of reclamation on macrobenthic community in the Hengsha East Shoal of Yangtze River EstuaryUsing ecological methods, we investigated the influence of reclamation on macrobenthic community in the terrestrial zone, the siltation zone and the nature tidal flat of the Hengsha East Shoal from April to December in2011. The investigation showed that a total of28species were found. The rank of the number of macrobenthos species were the nature tidal flat (22species)> the siltation zone (19species)> the terrestrial zone (7species). The rank of the dominant species were the nature tidal flat (6species)> the siltation zone (5species)> the terrestrial zone (2species). The rank of the average abundance of macrobenthos were the siltation zone (118.68ind./m2)> the terrestrial zone (100.67ind./m2)> the nature tidal flat (57.67ind./m2). The rank of the average biomass were the siltation zone (35.71g/m2)> the nature tidal flat (27.56g/m2)> the terrestrial zone (1.52g/m2). The rank of the Shannon-Wiener index(/H), Margalef index(d), Pielou index(J’) of macrobenthos were the nature tidal flat> the siltation zone> the terrestrial zone. The results of CLUSTER and MDS showed that there were significant differences among the three different habitats. The ABC curves also indicated that the macrobenthic community of the siltation zone and the terrestrial zone had been changed while the nature tidal flat were relatively undisturbed. In conclusion, reclamation has significantly changed the composition of macrobenthos.2. Macrobenthic functional groups at the reclamation and natural tidal flats of Hengsha East Shoal, the Estuary of Changjiang RiverFunctional groups of macrobenthos are vital for the assessment of the changes of ecological functions of wetland driven by natural and human factors. In order to get a better understanding of the functional groups of macrobenthos, the surveys were conducted in the reclamation tidal and the natural tidal flats of Hengsha East Shoal. The results demonstrated that19species and22species were found in and outside the dyke, respectively. Based on their food preferences, the macrobenthos were classified into5functional groups:Planktophagous group, Phytophagous group, Camivorous group, Omnivorous group and Detritivorous group. The number of species in each functional group was4,5,4,3,3in the reclamation tidal flat, and6,3,5,6,2in the natural tidal flat. The abundance of each functional group in proper order was Phytophagous> Planktophagous> Carnivorous> Omnivorous> Detritivorous in the reclamation tidal flat, and Planktophagous> Omnivorous> Camivorous> Detritivorous> Phytophagous in the natural tidal flat. The species number and abundance of each functional group were analyzed by the two-way ANOVA method. For the reclamation tidal flat, there was no significant difference among seasons for all of the species number and abundance except for the species number of Planktophagous group and Phytophagous group. Similarly, no significant difference was found among the tidal flats for the species number and abundance of each functional group except for the abundance of Phytophagous group. For the natural tidal flat, the difference was significant for the species number of Planktophagous group among the seasons, but not for others. However, most of the functional groups had significant difference among the tidal flats except for the species number and abundance of Phytophagous group. The Planktophagous group and Phytophagous group were the dominant functional groups at three tidal flats of the reclamation tidal flat. The dominant functional groups of the natural tidal flat, however, were Planktophagous at high tidal flat, Planktophagous and Omnivorous at middle tidal flat, Omnivorous at low tidal flat, respectively. In the reclamation tidal flat, Planktophagous group and Phytophagous group had the higher diversity indices(H’, J’, d), while Omnivorous group had the lower diversity indices. In the natural tidal flat, Camivorous group and Omnivorous group had the higher diversity indices, while Phytophagous group had the lower diversity indices.In conclusion, the composition of functional groups between the reclamation tidal flat and the natural tidal flat was distinctly different. And the changes of the functional groups among the tidal flats were often associated with habitats. The reclamation had resulted in the variations of the communities and functional groups in macrobenthos.3. The ecological research of macrobenthos of constructed oyster reef in the Yangtze River EstuaryAn intertidal oyster reef was created by planting hatchery-reared seed oysters on an artificial concrete modular reef in the Deepwater Navigation Channel Regulation Project of the Yangtze River estuary. We examined the macrobenthos of artificial oyster reef in. July and October of2012. The results indicated that the average abundance and average biomass of Crassostrea rivularis were416.33ind./m2and7197g/m2, while that of Fistulobalanus albicostatus were1706.11ind./m2and 3856.69g/m2respectively. The oyster reef also supported22species of macrobenthos. which were not including C. rivularis and F. albicostatus. The abundance and biomass of these macrobenthos were457.64ind./m2and83.61g/m2, while the reef-associated communities were numerically dominated by Neanthes japonica, Perinereis aibuhitensis, Nerita yoldi, Littorina brevicula and Gnorimosphaeroma rayi. Two-way ANOVA analysis of data on C. rivularis, F. albicostatus and other macrobenthos were adopted to analyze the difference among the six sampling sites and three tidal flats. The results demonstrated that the abundance of C. rivularis were significant different among three tidal flats as well as the biomass of C. rivularis and F. albicostatus, while the abundance and biomass of other macrobenthos were significant different among the sampling sites. The results of cluster and correlation analysis showed that the characteristics of species composition and community structure had obvious relationship with changes in salinity. |
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