[Labidocera euchaeta: its distribution in Yangtze River Estuary and responses to global warming].

Based on the investigation data from eight oceanographic censuses in Yangtze River Estuary (28 degrees 00'-32 degrees 00' N, 122 degrees 00'-123 degrees 30' E) in four seasons of 1959 and 2002, the seasonal distribution pattern of Labidocera euchaeta in the Estuary and the responses of this zooplankton to global warming were analyzed. In the study area, L. euchaeta had a higher average abundance in winter and spring than in summer and autumn, with the highest occurrence frequency in winter and an obvious aggregation in spring and summer. Water salinity was the key factor determining the horizontal distribution of L. euchaeta. The optimal water temperature and salinity for L. euchaeta were 16 degrees C and 12-20, respectively, indicating that this zooplankton belonged to a warm temperate brackish water species. Comparing with that in 1959, the abundance of L. euchaeta in 2002 decreased obviously, which could be related to global warming and suggested that L. euchaeta could be used as an important indictor species of ocean warming in Yangtze River Estuary. The high abundance of L. euchaeta in spring appeared in the most turbid zone of Yangtze River Estuary, being of significance in maintaining the functions of fishing grounds in the waters.