Long-term Changes Of The Macrobenthic Community Structure In The Cold Water Mass Of The Southern Yellow Sea

Based on the data of macrobenthic samples collected from southern Yellow Sea in the summer of 1959,2004,2011,2012 and 2013 and the data of community characteristics of mollusc in the summer of 2011—2013 were studied.The aim of this study is to analysis the community structure inside and outside of the cold water mass core of the souther Yellow Sea(YSCWMC)and the relationships between the mollusc community and the cold water mass of the Yellow Sea(YSCWM).Shannon-Wiener index(H'),Pielou index(J'),Margalef index(d),average taxonomic distinctness index(?+),abundance and biomass were calculated to describe the community characteristics.AMBI?M-AMBI index,Variation in taxonomic distinctness index(?+)and abundance-biomass comparison(ABC)curves were used to determine the status of the communities.One-way ANOVA and two-way ANOVA were used to analyze the significance between communities.In the five surveys,altogether 45/104 species were found in/out of the YSCWMC.Specie kinds in YSCWMC slightly reduce during 50 years.The variation in community component was slightly greater in the outside than the inside,which is also true as shown in ABC curve.Molluscs were obviously more abundant inside than outside in biomass with very little change in species composition.Polychaeta and Echinodermata were major contributor to biomass but very few in varieties inside the core,while in the outside,they dominated in both biomass and variety.Thyasira tokunagai,Raetellops pulchella,Periplomatidae,Nuculanida,and Portlandia japonica were main and common species inside the water mass.Therefore,YSCWMC could provide a favorable condition for mollusc growth and propagation,also maintain its community structure.The analysis in 2011 to 2013 shows that the abundance of molluscs decreased from the north area to the south in the southern Yellow Sea.Moreover,the abundance in the YSCWM was higher than that outside of the YSCWM.Mollusc community structure in the southern Yellow Sea was relative stable compared with the research in 2006.