Community Structure Of Zooplankton In The East China Sea And The Yellow Sea

In this paper, zooplankton communities, their species composition and indicator species in the East China Sea and the Yellow Sea were examined with multivariate methods. In the southern part of the Yellow Sea, where was known as an important spawning ground of anchovy, the seasonal variations of zooplankton were studied in details with respect to species composition, abundance, biomass and vertical distribution. Furthermore zooplankton indication of the Yellow Sea Warm Current (YSWC) in winter was discussed. Results as following:In the East China Sea and the Yellow Sea, zooplankton showed higher diversity in the low latitude and warm species occurred mainly in the south of 31°N, five communities were distinguished by TWINSPAN method, based on data of species composition and environmental factors. They are: i) Yellow Sea Neritic Community (F) with indicator species of Labidocera euchaeta in autumn and Centropages mcmurrichi in spring; ii) Yellow Sea Central Community (HC) with indicator species of Themisto gracilipes, Calanus sinicus and Euphausia pacifica, the latter two species occurred only in autumn; iii) East China Sea Continental Shelf Mixed Water Community (K) with indicator species such as Rhincalanus cornutus and Pterosagitta draco which were confined in waters with high temperature and salinity, iv) Yellow Sea and East China Sea Mixed Water Community (HE) and v) East China Sea Inshore Mixed Water Community (M). Both the HE and M communities were consisted of species belonging to diverse ecotypes, but temperate species was more dominant in HE whilewide-distributed warm species showed more preference in M. From the mutiple-regression, temperature and salinity in surface water were the most important environmental factors for the zooplankton distribution and community classification.In the southern part of the Yellow Sea, zooplankton showed decennial changes as the abundance, biomass and diversity of zooplankton, the ratio of abundance of Calanus sinicus to that of Sagitta crassa all increased comparing with the data correspondingly in 1959. The distribution pattern of the warm water species showed clearly that the YSWC flows beneath the surface northwards into the Yellow Sea along the Yellow Sea Trough, the north limit to what the YSWC can penetrate was about 35-36°N and the intrusion of the warm water took place mainly in the middle layer. Temperature was the determinative factor for zooplankton vertical distribution according to canonical correlation analysis(CCA). The seasonal variations of vertical distribution of C. sinicus and T. gracilipes, provided evidence that Yellow Sea Bottom Cold Water was served as an oversummering site by some temperate species which preferred to live in waters with relative low temperature.