Ecological And Environmental Effect On Macrofaunal Communities In Mangrove And Salt Marshes In Quanzhou Bay

The mangrove and Spartina alterniflora are two typical ecological wetlands on intertidal zone, while the macrofaunal community is a key part of intertidal ecosystem. Studies on macrofaunal community not only supply the more crucial ecological process of intertidal coast, but also accurately assess ecological and environmental quality of the intertidal zone. Although many studies on macrofauna in intertidal mangrove and salt marshes in China have been done, two key problems have not been solved.(1) Different dentification lelve has been found in many researchers, which got different results, even the opposite.(2) Few studies on comparing macrofaunal communities in different habitats. In this study, the samplings were set depending on different habitats, a variety of mathematical statistics and biological index were used, especially the M-AMBI and so on, for comparing and evaluating the environmental quality of the mangrove and Spartina alterniflora wetlands. The rusults might providing the scientific basis for mangrove planning, Spartina alterniflora controlling and utilization of resources. The main results are as follows:1. One hundred and seventy-one macrofaunal species were identified in mangrove and salt marshes of Quanzhou Bay intertidal zone. Among them,67species belonged to Polychaeta,46species belonged to Crustacean,21species belonged to Gastropoda and24species belonged to Bivalvia. There were57species of macrofauna in Luoyang estuarine mangrove wetland,89species in Baisha inertidal zone and101species in Xunpu inertidal zone. The species numbers had an increasing trend from inner bay to outer bay.2. CLUSTER and MDS analysis showed that there were three macrofaunal communities from inner bay to outer bay. Oligochaeta-Actinia sp.-Assiminea brevicula were dominant macrofaunal species in Luoyang estuarine mangrove wetland. NepHtys oligobranchia-Capitella capitata-Assiminea brevicula were dominant macrofaunal species in Baisha mangrove wetland and salt marsh. Mediomastus californiensis-Nephtys oligobranchia-Glycera chirori were dominant macrofaunal species in Xunpu salt marsh.3. The average density of macrofauna in Luoyang, Baisha and Xunpu mangrove and salt marshes was870.4ind·m-2,462.0ind·m-2and1628.3ind·m-2respectively, While the average biomass was46.10g·m-2,25.97g·m-2and50.00g·m-2respectively. The reason of the low density and biomass in Baisha intertidal zone was that the aquaculture wastewater was discharged, which led to higher density of pollution resistant species Capitella capitata and lower density of big individuals of macrofauna.4. The average species diversity index of macrofaunal community in Spartina alterniflora wetland in Luoyang and Xunpu (3.70and2.80) was higher than other habitats within each intertidal zone, which showed the Spartina alterniflora habitats in Quanzhou Bay intertidal zone were favorable for the living of macrofauna. MPI, AMBI and M-AMBI showed that ecological quality of majority intertidal zones in Quanzhou Bay belonged to good or even not disturbed habitats.5. Salinity in Baisha intertidal zone was lower than those in Luoyang and Xunpu intertidal zones, which was related to discharging aquaculture wastewater. There was not significant correlation between majority parameters of macrofaunal community and environment factors, sedimental grain size in Quanzhou Bay intertidal zone. The relationship between the species of macrofauna and the groups, density, biomass of meiofauna was significant correlation, while the relationship between density, biomass of macrofauna and groups, biomass of meiofauna was not. These results indicated that the environmental factors effecting on macrofaunal communities in Quanzhou Bay intertidal zones were not intense, and there was existing food web between meiofaunal community and macrofaunal community.6. Composition of macrofaunal functional groups in Quanzhou Bay. There was no planktophagous group in Luoyang estuarine mangrove wetland, the detritivorous group accounted for a higher proportion of macrofaunal density, while the phytophagous group accounted for a higher proportion of macrofaunal biomass. The desity composition in Baisha and Xunpu intertidal zone was more complex, simultaneously, the phytophagous group accounted for a higher proportion of biomass in Baisha and Xunpu intertidal zones.