中文摘要：

根据2005年4和11月、2006年4 和9月在长江河口水域进行的鱼卵、仔稚鱼种类和数量调查, 并结合1990 年9 月和1991年3月的历史数据, 对该水域的鱼卵、仔稚鱼群落结构的种类组成和数量的季节变化作了研究,其结果共发现鱼卵、仔稚鱼36 种（类）, 以海洋鱼类种类最多。秋季航次鱼卵、仔稚鱼的平均种类数和丰度均高于春季。河口咸淡水区鱼卵总数显著高于淡水区, 而仔稚鱼总数略低于淡水区。与1990-1991 年数据相比,2005-2006 年春、秋季的鱼卵和仔稚鱼丰度均有所增加。1990、2006 年秋季（9 月）鱼卵、仔稚鱼种类组成差异较大, 特别是翘嘴红鲌和太湖新银鱼丰度差异较大。这些都说明近20 年来, 长江河口水域鱼卵、仔稚鱼种类组成和数量均发生了明显的改变。

英文摘要：

Based on four surveys of eggs and larvae in the Yangtze estuary in 2005 （April and November） and 2006 （April and September）, combined with the historical data of the wetland in 1990 （September） and 1991 （March）, we analyzed seasonal changes in fish species composition and quantity of ichthyoplankton. Thirty-six species of egg and larvae were collected and marine fish species were the highest represented ecological guild. Average fish species and average abundance in spring were lower than in autumn for every survey. The total number of eggs in brackish water was higher than in fresh water, but the total number of larvae and juveniles in brackish water was lower. The abundance of eggs and larvae during from 2005 to 2006 in both spring and autumn was higher compared to those from 1990 to 1991. Obvious differences in species composition in September between 1990 and 2006 were found, especially for Erythroculter ilishaeformis and Neosalanx taihuensis. Fish species composition and quantity within the ichthyoplankton community has obviously changed in the Yangtze estuary over the last 20 years.