Community Structure Of Invertebrate Resting Eggs In Shanghai Waters

When aquatic invertebrates come across the stress, such as malignant transformation of environment, lacking of food and population density increased sharply, many taxa can produce resting eggs. Varieties of resting eggs accumulate in the sediment and form an egg bank. Aquatic invertebrate resting eggs play an important role in the species abundance, diversity of community, species evolution and diffusion. Urbanization is the trend of social and economic development and the environmental problems caused by the urbanization can be directly reflected in the urban aquatic ecosystem. Formation of a large number of resting eggs was usually related to the water pollution. Therefore, abundance and diversity of resting eggs probably referred to the degree of water pollution.I chose the reclaimed urban reclamation area (Chongming Dongtan), rivers network (5 rivers, Suzhou River included), small lakes (30 lakes in Parks) as the research areas, and investigated the species diversity and community structure of resting eggs. After separating the resting eggs from sediment by sucrose density gradient centrifugation, extracting the DNA of a single resting egg by HotShot method, and amplifying the COI gene by invertebrate universal primer LCOI490 and HCO2198, a DNA sequence of 700 bases was obtained and species information was searched from the NCBI database. Following the molecular identification of resting eggs, I counted resting eggs under the microscope and finally obtained the community structure of resting eggs.The main conclusions were listed as follows:(1) I found 94 species resting eggs in sediment of Shanghai waters, including cladoceras (18 kinds), copepods (11 kinds), rotifers (29 kings) and others (36 kinds). I obtained 204 COI gene sequences through the molecular identification method. And 67 species’ COI gene sequences had been obtained, including Arthropoda, Porifera and Bryozoan and so on. Nineteen of them were classified to species, forty three of them were classified to taxa, and five of them couldn’t be classified successfully.(2) Resting eggs were found in tidal creeks and flat in city’s reclamation area, with lower abundance and species diversity. The community structure was dominated by copepods, and rotifers were more than cladoceras. The dominant resting eggs were Sinocalanus tenellus, Labidocera rotunda and Centropages tenuiremis. Abundance of resting eggs in reclamation was significantly higher than natural tidal creeks, with the same dormant resting eggs and community structure.(3) Artificial rivers’abundance of resting eggs was significantly lower than the natural rivers in network of rivers in Shanghai, similar with tidal flat tidal creeks and flat. Community structure was mainly dominated by Brachionus calyciflorus or Sinocalanus tenellus, and the Cladocera was least. The distribution of resting eggs among the most natural rivers sampling stations was different. Abundance and species diversity of resting eggs in most sampling stations of Artificial rivers was low, with simpler community structure and consistent trend. Abundance of resting eggs increased significantly in junctional region between urban and suburban areas, which had high population density and industrial emissions. However, Community structure tent to simplify, dominated by Sinocalanus tenellus or Brachionus calyciflorus.(4) Resting eggs were found in all small lakes in Shanghai and the species diversity was high. Resting eggs’abundance was low and had similar community structures in lakes in Changxing Island and Hengsha Island. The distribution of resting eggs in other lakes was significantly different in species, abundance and community structure without obvious regional differences.This research on distribution of resting eggs in typical waters in Shanghai, not only could broaden the research on distribution of resting eggs, but also could promote the understanding about the characteristics of resting eggs’community structure. Furthermore, it has provided scientific data for elucidating the influence of urbanization on city waters’ ecosystem.