中文摘要：

根据1997—2000年东海23°30＇-33°00’N、118°30’-128°00’E海域4个季节海洋调查资料，从环境因素与优势种的聚集强度等不同侧面探讨了东海水母类多样性指数（H＇）的分布特征及其成因。东海4季共发现水母类103种，主要分布在东海南部和北部外海。大部分水域水母物种多样性较高，且冬夏季高于春秋季。南部高于北部，外海高于近海。分析成因如下：（1）多样性指数与物种数密切相关，但与丰度相关性不显著。优势种的聚集导致个别海区物种多样性降低。春季五角水母（Muggiaea atlantica）在浙江近海、秋季双生水母（Diphyes chamissonis）在长江口海域聚集，导致春秋季东海近海水母类多样性指数较低。（2）水温是影响多样性指数分布的主要环境因子，盐度是次要因子。冬春季多样性指数值与10m层水温相关，夏季与表层水温相关，秋季与10m层盐度相关。（3）多样性指数的分布还受不同水团的影响。春季、夏季和冬季多样性指数（H3等值线分布全面反映了东海海流走向和水团的变化。是分析东海水团的良好指标。

英文摘要：

Based on the maritime data collected from 23°30＇-33°00＇ N and 118°30＇-128°00＇ E of the East China Sea in four seasons during 1997-2000, we analyzed the dynamics of medusa diversity and the causes. A total of 103 medusa species were observed, which were mainly distributed in southern and northern offshore of the East China Sea. Higher species diversity indices （H9 of medusa occurred, respectively, in the southern part of the sea, offshore, and in summer and winter. The number of species was closely correlated with H＇ value, whereas the abundance was not correlated with it significantly. The lower H＇ value nearshore in spring and autumn resulted from the aggregation of Muggiaea atlantica nearshore of Zhejiang Province and Diphyes chamissonis at the Yangtze River estuary. Water temperature, followed by salinity, was main environmental factor influencing the distribution of species diversity. H＇ value was related to the water temperature of 10 m layer in winter and spring, while it is associated with surface water temperature in summer and with 10 m-salinity-layer in autumn. The isoline distribution of H＇ value reflected the direction of currents and changes in water masses in the East China Sea, the H＇ isoline was a good indicator for analyzing the East Sea cold masses.