| Study of zooplankton was conducted on two cruises of investigation for the South Yellow Sea in December 2009 and January 2010.Species composition, abundance, biomass and dominant species were studied. Zooplankton community structure and biodiversity were analyzed through multivariate analysis method. The indication of warm water zooplankton to the warm the Yellow Sea Warm Current (YSWC) was also analyzed based on these data.A total of 87 zooplankton taxa were identified during two surveys. The zooplankton community was dominated by temperate and warm-temperate species. Calanus sinicus, Sagitta crassa, Themisto gracilipes were still the overwhelming species. The mean abundance value of zooplankton collected with 500μm net was 22.13 ind/m~3,and the mean biomass was 41.03 mg/m~3.Both of them were correlated with depth, which was opposite to the abundance of zooplankton collected with 160μm net. It was caused by the capture efficiency of the different nets to the small mesozooplankton. Three groups were distinguished by the cluster analysis method, based on the species composition and abundance of zooplankton. Few influence of YSWC on Shannon-Weaver Index, Richness Index and Evenness Index was found during the study period.In December 2009, most warm water species were found in the southeast part of survey area where YSWC intruding. In January 2010, more warm water species were found between 35 and 36°N. The locations of the tropical species Candacia truncata and Clausocalanus furcatus were consistent with the path of the YSWC. The distribution of the amount of Euchaeta rimana presented the northward trend in comparison with that in December, 2009. Principal Component Analysis (PCA) analysis indicated that occurring of warm species was related to seawater temperature, which showed the indication of the path and range of Yellow Sea Warm Current. The warm tongue was observed in December, and the intruding of nutrient happened in the southeast part of survey area.
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