Abstract: Based on the investigations in four seasons from 1997 to 2000, this paper studied the seasonal quantitative variation and geographical distribution characters of Ctenophora in East China Sea (23°30′～33°00′N、118°30′～128°00′E). The results showed that the abundance of Ctenophora peaked in autumn (6.3 ind·（100 m³）^-1), followed by in spring (1.6 ind·（100 m³）^-1), winter (1.4 ind·（100 m³）^-1), and summer (0.6 ind·（100 m³）^-1) . A total of six species were observed, among which, Pleurobrachia globosa was the most important species, Hormiphora palnata and Beroe cucumis were the common species, Cestum sp. was the subordinate species, while Ocyropsis crystalline and B. avata were the rare species. The Ctenophora in East China Sea was a kind of warm water species, because its quantitative variation had a close relation with the motion of warm water current, and the key factor affecting Ctenophora abundance was warm water current but not the seasonal change of temperature. In all species of Ctenophora,P. globosa had stronger adaptability to its environment, followed by Cestum sp. and B. cucumis, and H. palnata, Ocyropsis crystalline and B. avata.

Key words: Fenpropathrin, Phoxim, Mixture of pesticides, Soil microbe, Degradation