Study on ecology of meso-small pelagic copepods in the Southern Yellow Sea and the East China Sea II. species composition and community characteristics

The relationship between community compositon and environmental condition of meso small pelagic copepods netted with mesh size 0.16 mm in the southern Yellow Sea and the East China Sea (28°00′-34°00′N、121°00′-127°00′E) was focally discussed in the paper. The experimental results show that there were 71 species of meso small pelagic copepods grown in four seasons, accounting for 83.1% of the total species. The seasonal variation in the community composition was not remarkable. More species existed in the southern part and oceanic sea, and less in the northern and nearshore waters. There were 15 dominant species appearing in four seasons, among them Oithona similis, Paracalanus parvus, Corycaeus affinis, etc were main dominants (dominance Y≥0.02) . In autumn,Aegisthus mucronatus,Calocalanus pavo , Calocalanus pavoninus, etc would be instead of the above species. The calculated value of alternative rate R for dominant species showed that the habitant environment for meso small copepods community in the investigated area varied greatly in summer turning to autumn and relatively less in winter turning to summer. The average value for species diversity ( H′), homogeneity (J′) and single purity (C) of pelagic copepods in four seasons were 2.58(2.27-2.99), 0.72( 0.64 -0.7)and 0.26(0.21-0.38) respectively. The horizontal distribution of H′value was basically correspondent to the species distribution.