Study On The Composition Of Benthic Fauna And The Heavy Metal Content Of Surface Sediments In The Migratory Habitat Of Plovers Along The Coast Of Southern Jiangsu

Shorebirds in long-distance migrations need to utilize a series of stopover sites for supplementing food and accumulating energy,so that they can continue the next migration.In addition,shorebirds may face harsh environmental conditions such as severe cold and lack of food with arriving early at breeding ground,so the food and nutrients which were saved in stopover sites would play a key role in successful breeding.In conclusion,stopover sites have vital significance in shorebirds smooth migration and completing the full life cycle.The paper chose important shorebirds stopover site-Southern Jiangsu intertidal zone(Tiaozini,Yangkou,Dongling)as the study area.The community structure of zoobenthos,the relationship between zoobenthos and physical and chemical factors and the distribution,pollution status and sources of heavy metals were investigated in study area.The research results will provide scientific basis for protecting wetlands ecosystem and migratory shorebirds.The main results were as follows:1.A total of 126 species of zoobenthos were found,belonging to 10 phyla,32 orders and 71 families.Among them,16 species have distribution on all survey transects and intertidal zones.2.There were no significant differences in species,density and biomass of zoobenthos between spring and autumn,among different transects and among different intertidal zones.There were significant differences in Shannon-Weiner index and Pielou index among different transects.There were significant differences in Margalef index among transects and among intertidal zones.Hierarchical cluster and Non-Matric Multi-Dimentional Scaling(MDS)showed that the similarity and grouping were different among different positions in spring and autumn,and similarity in spring being slightly higher than in autumn.In addition,the grouping did not show the obvious differentiation between bare flats and Spartina alterniflora zones and among different intertidal zones.3.The changes of dominant species composition and density caused by physical and chemical factors(pH,mV,salinity,TDS,ELE and RES)would influence zoobenthos community structure.The correlation between physical and chemical factors and dominant species varied with seasons and species.And the influence of physical and chemical factors on heavy metals content and distribution varied with seasons and heavy metals.4.The content of Cu,Zn,Cd,Cr and Hg were overall at low level.The content of Pb was about the same with other area.The content of As was slightly higher than the surrounding area.There were no significant differences in the contents of heavy metals in shorebird stopover sites of southern Jiangsu,except for As and Hg in different season,Cu and Zn among different intertidal zones,and Cd in different transects.5.The assessment by geoaccumulation index in the whole areas indicated that Zn,Cr,Hg and Cu were practically uncontaminated,As and Pb were uncontaminated to moderately contaminated both in spring and autumn,and Cd was moderately contaminated in spring and uncontaminated to moderately contaminated in autumn.The assessment by the potential ecological risk index indicated that the potential ecological risk of As,Pb,Cu,Hg,Zn and Cr were at the low risk level,and Cd was at considerable risk level in the whole.6.PCA showed the heavy metals mainly came from industrial emissions of the Rudong Economic Development Zone,motor vehicle exhaust and the ship pollution emissions of the local fishing ports.