Ecological characteristics of meso-and micro-zooplankton in macro-jellyfish bloom areas of Southern Yellow Sea.

From May to September 2007,a survey was conducted to investigate the species composition,community characteristics,and dominant species of meso-and micro-zooplankton in the macro-jellyfish bloom areas of Southern Yellow Sea(121°15′E-122°09′E,31°53′N-32°53′ N) . Zooplankton net(0.160 mm mesh size) was used to collect the samples from six investigation sites(St.1,St.2,St.3,St.4,St.5,and St.6) . A total of 58 species belonging to 11 groups and 5 phyla were identified,among which,Copepod was the most dominant group,consisting of 80.86% of the total abundance of zooplankton. The average abundance of the zooplankton was 783.17 ind·m-3(ranging 452.23-1241.86 ind·m-3) ,with the highest density at St.4,and the mean value of diversity index(H′) was 2.76(2.44-2.95) ,being higher at southern part(St.4-St.6) than at northern part(St.1-St.3) . Paracalanus parvus was the most dominant species and concentrated at St.4,with the average abundance being 263.76 ind·m-3(152.23-451.89 ind·m-3) . The total abundance and gross biomass of the zooplankton in the investigated areas depended on the abundance of P. parvus. There was a significant positive correlation between zooplankton biomass and gross catch per unit effort(CPUE) ,and a significant negative correlation between macro-jellyfish CPUE and gross CPUE,and between macro-jellyfish CPUE and Pseudosciaena polyactis CPUE.