Studies On Assemblages Of Benthic Polychaetes In Beibu Gulf

Polychaetes is an important component of the benthic ecosystem as well as a positive comsumer of material cycling and energy flowing. Many species work as bio-indicators to appraise the quality of sediment. Polychaeta as the largest species number and density group among benthic animals, the study of which species composing, biomass change, seasonal difference and the relationship with environmental factors is very significant. It can not only light the particular of a specific research area, also provide a benthic ecological basis for marine environment restoration, protection and exploitation.Base on the National Inshore Research and Appraisal Project (908 Project), we choosed Beibu Gulf as the research area, focus on the polychaeta from benthic animals, and analyzed species composing, biomass change, seasonal difference of polychaeta, different univariate and multi-variable analysis were used to study the community traits of polychaeta from Beibu Gulf. Compared with the history data and the change of species number and biomass of polychaeta were found. The main results are as follows:1. Total 308 species of benthic polychaeta were identified in the four seasons in Beibu Gulf, they belonged to 45 families and 152 genus. The three most populated areas are the coast of Guangxi province, the area near Bailongwei island and the south area of Hainan island. The species number of polychaeta was 171 in spring, 207 in summer, 135 in autumn and 180 in winter. The dominant species are Aglaophamus dibranchis, Notomastus latericeus, Magelona crenulifrons, Prionospio malmgreni, Paralacydonia paradoxa in spring, Magelona crenulifrons and Terebellides stroemii in summer, Aglaophamus dibranchis in autumn, Aglaophamus dibranchis, Magelona crenulifrons, Aglaophamus sp. and Lumbrineris sp.in winter.2. The benthic polychaeta mean density is 193.41 ind/m~2, mean biomass is 2.62g/m~2. In summer,the polychaeta mean density is the highest, spring and winter are average, and it's the lowest in autumn. In winter, the polychaeta mean biomass is the highest, summer and spring are average , and it's the lowest in autumn3. Used the mean similarity of benthic polychaeta from each season from each research station, cluster analysis was done and the result showed there were three main communities of benthic polychaeta in Beibu Gulf. One located in the north of Beibu Gulf, the second one located in the west of Hainan island and the third one located in the south of Hainan island.4. Used the PCA analysis, it showed that the different environmental factors in each season had certain relativity with polychaeta density. Used the CCA analysis, it showed the different environmental factors in each season had certain relativity with certain polychaeta species.5. Comparing with the history data from the same and world wide research area, it shows that the polychaeta species composition, density and seasonal change was quite different in Beibu Gulf.