Seasonal Variation Of Zooplankton Community Structure And Diversity Characteristics In Zhoushan Offshore

Based on the plankton surveys conducted in 2019 on four cruises off the coast of Zhoushan in the spring(April),autumn(November),summer(August)and winter(December)of 2020,this thesis presents a survey of plankton in the waters off the coast of Zhoushan,to study the community structure and biodiversity of zooplankton in the waters off the coast of Zhoushan Zhoushan,and to explore the relationship between the seasonal variation of zooplankton and environmental factors.Using the similarity percentage analysis and single factor similarity analysis,we analyzed the differences of zooplankton in the four seasons off the coast of Zhoushan,and the species and contribution rates that caused the seasonal differences,Pearson correlation analysis and canonical correspondence analysis(CCA)were used to study the relationship between zooplankton and environmental factors,the non-parametric multivariate variance analysis(Permanova)was used to study the significance of the difference of the four-season community structure and Biodiversity Index.The results showed that 100 species of zooplankton of 14 species were identified in the study area,there are 37 species of Copepoda,23 species of Medusae,9species of Pelagic larvae,5 species of Mysida,4 species of Acropoda,4 species of Decapoda,4 species of Polychaeta,2 species of Pelagic mollusks,2 species of Krill,2species of Chaetognathus,2 species of Ostracoda,2 species of Cladocera,2 species of Tunicate species and 2 species of others.There are 3 dominant species in spring,namely C.sinicus、N.scintillans、M.atlantica;There are 9 dominant species in summer,namely M.zoea、S.nagae、Brachyura zoea larva、Oikopleura dioica、Genus Acartia、L.intermedius、C.sinicus、D.chamissonis、E.concinna;There are 7 dominant species in autumn,namely P.sinica、Brachyura zoea larva、Order Microseteua、Calanus sinicus larva、S.nagae、E.pacifica、L.subtiloides;There are 5 dominant species in winter,namely C.sinicus、D.chamissonis、L.intermedius、E.concinna、S.nagae.Copepoda is the first dominant group in all seasons.The total zooplankton species in spring,summer,autumn and winter accounted for 33.3%,34.0%,39.1% and 33.3% respectively.The abundance of zooplankton was Spring > Autumn > Summer > Winter,and the diversity index of zooplankton was Winter > Autumn > Summer > Spring.The results of Permanova test showed that seasons had significant effects on the community structure,species number s,abundance D,evenness J and Diversity H of zooplankton,but there was no significant difference in the spatial distribution of zooplankton between islands and reefs.CCA results showed that salinity was the main environmental factor,temperature and CHLOROPHYLL-A were the main environmental factors,the low temperature and high chlorophyll content in spring are favorable for the outbreak of zooplankton dominant species.In this study,the seasonal variation of zooplankton community structure and biodiversity in the coastal waters of Zhoushan and its relationship with environmental factors were studied,to provide a scientific basis for ecological restoration of fishing grounds in Zhoushan.