Studies On The Meso-and Macro-zooplankton Community Ecology In The Yellow River Estuary And Its Adjacent Waters In Summer And Autumn

Zooplankton community structure and its influencing factors were studied by means of multi-variable and bio-environmental analysis based on the samples collected in the Yellow River Estuary and its adjacent waters during two survey cruises which was conducted in summer (Jul. 2009) and in autumn (Sep. 2010) separately. The research can provide important fundamental information for the long-term monitoring of zooplankton structure ecology in the Yellow River Estuary.A total of 63 zooplankton taxa and 16 pelagic larvae were identified during two surveys, and they belonged to Protozoa, Cnidaria, Ctenophora, Mollusca, Arthropoda, Chaetognatha and Urochordata. Crustacea and Chaetognatha were the most abundant two components of the zooplankton. The species percentage of pelagic crustacean represented above 57.1% of total species richness and copepods were the most dominant crustacean in surveyed waters.In summer, the mean abundance of zooplankton was 303.8 ind/m~3. The high abundance was near the estuary and the north part of the surveyed waters. In autumn, the mean abundance value of zooplankton was 229.6 ind/m~3. The abundance in the north-eastern area of the surveyed waters was also higher than other area. Copepods, pelagic larvae and Chaetognatha was the most important dominant groups in the Yellow River Estuary which greatly controlled the distribution of tatal zooplankton abundance.In summer, the mean biomass was 325.1 mg/m~3. The biomass was higher near the estuary waters and the northern part of surveyed area, though the biomass is relatively lower in the southern area. In autumn, the mean biomass was 924.1 mg/m~3, the biomass in the north-eastern waters was higher than that in the southern waters.Sagitta crassa, Calanus sinicus, Macrura larvae, Paracalanus parvus and Labidocera euchaeta were the dominant species in summer, while Sagitta crassa, Calanus sinicus, Eirene ceylonensis, Pleurobrachia globosa and Centropages dorsispinatus were the dominant species in autumn.According to the multivariate analysis, significant differences of zooplankton communities were detected in the Yellow River Estuary. Three assemblages or communities were differentiated for the zooplankton by using the method of cluster analysis. GroupⅠ, with simple species composation, was detected in the neighborhood of Yellow River Estuary, as a result of the great influence from the Yellow River discharge. GroupⅡ, which was detected in autumn, was influenced by LaiZhou waters and the Yellow River discharge. GroupⅢ, with relatively more number of zooplankton species, was influnced by the waters which was under the control of both Yellow River discharge and BoHai coastal waters. The present study showed a clear relationship between zooplankton assemblages and water masses distributions. Surface salinity and water depth were the most important abiotic factors for the zooplankton distribution and community classification in summer, while in antumn, bottom salinity, bottom temperature and depth were the primary factors which influenced the zooplankton distribution and abundance in the surveyed area.Zooplankton biodiversity was significantly higher in summer than that in autumn. In summer, the average value of Species number, Shannon-Weaner Diversity, Pielou′s evenness index and Margalef species richness were 21, 2.45, 0.59 and 2.49, while in winter, the values were 15, 2.31, 0.54 and 1.80 respectively.