Analysis on Community Structure of Zooplankton in Zhoushan Fishing Ground and Its Adjacent Area in Summer

Based on the data acquired within the Zhoushan fishing ground and its adjacent area (29°30′ −31°30′ N, 121°30′ −124°30′ E), species composition, abundance, and species diversity of zooplankton were sampled by plankton net (50 cm mouth-diameter, 145 cm net length, 0.505 mm mesh-aperture) during August 2006. The results identified 93 species (exclude Larvae) from the samples, among which Copepods were the most diverse with 50 species. According to the standard of IRI (the species with IRI above 0.02 were regarded as dominant species in this paper), there were 12 dominant species: Euchaeta concinna, Dolioletta gegenbauri, Sagitta enflata, Sagitta bedoti, Calanus sinicus, Undinula vulgaris, Canthocalanus paupe, Macruran larvae, Diphyes chamissoni, Centropages dorsispinatus, Evadne tergestina, Acartia pacifica. The stations of high abundance were mainly in the southern part and oceanic sea, and low in the northern and near shore waters. Zooplankton in the Zhoushan fishing ground and its adjacent area exhibited high in evenness (0.70), high species number and high diversity indices (4.98). By hierarchical cluster analysis and non-metric multidimensional scaling (MDS) assisted analyzing, zooplankton in Zhoushan fishing ground and its adjacent area could be formed into three assemblages joining at a distance of 17.13%. The biota-environment matching (BIOENV) analysis showed that the abundance of zooplankton was correlated closely not only to salinity, nitrate, silicate, but also to the Cd and Pb.