Abstract:Based on the data from eight seasonal oceanographic censuses in the Changjiang Estuary (28°00′-32°00′N, 122°00′-123°30′ E) in 1959 and 2002, this paper discussed temporal\|spatial distributions of Sagitta crassa and Sagitta enflata and effects of global warming on them in the Changjiang Estuary. The results show that the average abundance of S. crassa was less than 1.00 ind/m3, and its occurrence frequency was lower, had no aggregate feature during spring, summer and autumn. In the winter of 1959 the average abundance was 3.24 ind/m3, and the occurrence frequency and aggregation intensity were higher, while in winter, 2002, the average abundance sharply decreased to 0.001 ind/m3, and almost disappeared. The average abundance, occurrence frequency and aggregation intensity of S. enflata were much higher in summer than in other seasons. The average abundance was as high as 16.06 ind/m3 in the summer of 2002, increasing by 3.71 ind/m3 compared to the same season in 1959, and the distribution area clearly expanded. It is obvious that responses of S. crassa and S. enflata to water temperature warming are different in the Changjiang Estuary, and both species could be awarded as important indicators of global warming.