春、夏季长江口邻近水域浮游动物优势种的生态特征

依据2000～2003年长江口邻近海域5月和8月8个航次的调查资料，对长江口浮游动物优势种的生态特征进行了研究。根据优势种出现的年份，平均丰度、优势度、聚集强度和对总丰度变化的回归贡献，确定本区优势种的重要性为真刺唇角水蚤（Labidocera euchaeta）〉中华哲水蚤（Calanus sinicus）〉背针胸刺水蚤（Centropage dorsispinatus）。太平洋纺锤水蚤（Acartia pacifica），火腿许水蚤（Schmackeria poplesia）和虫肢歪水蚤（Tortanus vermiculus）为次要优势种。马蹄娩螺（Limacina trochiformis）是偶然出现的优势种。中华哲水蚤在春季对总丰度贡献最大。真刺唇角水蚤是8个航次唯一的优势种，种群年间变化不显著。太平洋纺锤水蚤，火腿许水蚤和虫肢歪水蚤分布范围相对狭小，火腿许水蚤和虫肢歪水蚤分布在沿岸偏淡水的水体，适合较低的温度。太平洋纺锤水蚤分布在近岸偏成水的水体，适合较高的温度。

Ecological characters of zooplankton dominant species in the waters near the Changjiang estuary in spring and summer

Based on the data of 8 voyage's investigations in May and August from 2000 to 2003 in the fisheries waters near the Changjiang estuary,this paper dealt with the approach to ecological characters of zooplankton dominant species in this area.The importance of three main dominant species was determined as follows: Calanus sinicus>Labidocera euchaeta >Centropages dorsispinatus according to number of occurrence,mean abundance,dominance,aggregate intensity and regression contribution for abundance of dominant species to zooplankton total abundance.Acartia pacifica,Schmackeria poplesia and Tortanus vermiculus were three subordinate dominant species.Limacina trochiformis was the dominant species appeared one or two years.The contribution of Calanus sinicus to total abundance was the most valuable because of its high intensity and aggregation in May.It could become dominant species in Aug.when high salinity water invaded closely to the Changjiang estuary.Labidocera euchaeta,the only species occurred in all 8 voyage's investigations was low in ecological character value(mean abundance etc.) that seldom changed yearly and could adapt quite to wide temperature and salinity as though a alongshore species compared with other dominant species.Acartia pacifica,Schmackeria poplesiaand,Tortanus vermiculus distributed in a narrow area though they had rather high value of meanabundance,dominance,aggregate intensity and regression contribution for abundance of dominantspecies to total abundance.In these species,Acartia pacifica distributed in fresh-salt waters of offshore and adapted to higher water temperature while Schmackeria poplesia and Tortanus vermiculus at the seacoast are saitable to lower water temperature.