The Community Characteristics Of Zooplankton From WP2Net In The Yellow Sea In Summer And Autumn Of2011

Study of zooplankton was conducted on two cruises of investigation for theYellow Sea in summer（2011.6）and autumn（2011.11）. Zooplankton speciescomposition, abundance and biodiversity were studied. Zooplankton communitystructure was analyzed through multivariate analysis method. The purpose of thisresearch is to provide fundamental information for the long-term monitoring ofzooplankton ecology in the Yellow Sea. In addition，this study selected four sectionsof surveyed area in summer to evaluate the role of tidal fronts in the ecology ofParacalanus parvus and the primary production. The research provided significantinformation about the hydrological environment of the tidal front changes on thebiological element across the tidal fronts and even the marine ecosystem.A total of102zooplankton taxa（not including26pelagic larvae) were identifiedduring two surveys. The adult zooplankton species belong to Protozoa, Cnidaria,Ctenophora, Annelida, Arthropoda, Chaetognatha and Urochordata, respectively.Crustacea and pelagic larvae were the most abundant two components of thezooplankton. The species number of pelagic crustacean represented above33%oftotal species richness and copepods were the most dominant crustacean in surveyedwaters.During summer, the mean abundance value of zooplankton in surveyed waterswas12288.0ind/m3. The peak value was located in the northeast adjacent sea watersof Changjiang River Estuary and the coastal region of Shandong and Liaodongpeninsula. During winter, the mean value of which was2834.8ind/m3. The peak valuewas located in the central North Yellow Sea and the low value was located in the South Yellow Sea.In summer, the mean Margalef richness, Pielou’s evenness Shannon-Weaner indexvalue was1.15,0.51,1.52.The variation tendency of the species number, Margalefrichness, Pielou’s evenness and Shannon-Weaner index of zooplankton was thesame,high in the offshore area and low in the pelagic area;In autumn, the meanMargalef richness, Pielou’s evenness Shannon-Weaner index value was1.67,0.49,1.78.The variation tendency of the species number, Margalef richness, Pielou’s evennessand Shannon-Weaner index of zooplankton was the same.During summer,three groups were distinguished by the cluster analysis method,based on the species composition and abundance of zooplankton.ⅰ) CoastalCommunity（Cs）,the dominated species was Labidocera euchaeta. ⅱ)Yellow SeaMixed-water Community (YMs). It was influenced by the Yellow Sea cold water andthe offshore hot water.Its dominated species was Paracalanus parvus. ⅲ) Yellow SeaCommunity (Ys). It was influenced by the Yellow Sea cold water, and was dominatedwith Oithona similis,Calunus sinicus, Paracalanus parvus, Centropages abdominalis,Acartia clausi.During autumn,three groups were distinguished by the cluster analysismethod. ⅰ)Coastal Community（Ca）,the dominated species were Labidoceraeuchaeta. ⅱ) Yellow Sea Mixed-water Community (YMa), Oithona similis,Paracalanus parvus were the representative species.ⅲ) Yellow Sea Community (Ya),the dominated species were Oithona similis, Paracalanus parvus,Sagitta crassa,Corycaeus affinis.The survey results showed that the tidal fronts were existed in the surveyed areaand the abundance of P. parvus was one order of magnitude higher in the tidalfronts(18266.7ind/m3) than in the adjacent mixed areas(1480.0ind/m3) and itsabundance increased gradually from the stratification zone to the tidal fronts. Thesurface chlorophyll a concentration was high in the stratification zone(4.7μg/L) andlow in the tidal fronts(2.2μg/L).In the tidal fronts the abundance of P. parvus was highand the surface chlorophyll a concentration was low and this phenomenon suggestedthat the feeding pressure have an impact on the primary production.