2011年夏季胶州湾三种大型水母的种群动态研究

摘要

2011年8月1日-9月30日，对胶州湾三种大型水母沙海蛰（Nemopilemanomurai）、白色霞水母fCyaneanozakii）、海月水母似ureliaaurita）的种群数量变动及空间分布情况开展了目测调查，同步获得了气象、水温、盐度、叶绿素a、浮游动物丰度、种类组成等数据，调查频率为每周2次。调查期间，海月水母表现出逐渐降低的趋势，沙海蛰与白色霞水母种群均于8月11日达到数量高峰，8月底及9月中旬之后依次衰落，至9月底，三种水母基本消失。三种水母的种群平均丰度变化范围分别为：沙海蛰0—230．8ind／km0；霞水母0—150．2ind／km2；海月水母0—123．4ind／km2。从分布区域来看，海月水母主要位于近岸区，沙海蜇主要分布于湾口和中部深水区，而白色霞水母则在高峰期和次高峰期分别集中于深水区和近岸区。结合往年资料，作者认为，海月水母种群能够在胶州湾内进行自我补充并完成其生活史，而胶州湾沙海蛰与霞水母的种群补充则可能主要依赖于湾外种群。另外，目测方法的准确性可能受到气象条件的影响。%During August 1 to September 30, 2011, the population abundances and distributions of three scyphozoa jellyfish species Nemopelima nomurai, Cyanea nozakii and Aurelia aurita were examined by visual observation twice per week, along with the investigation of the metrological conditions, water temperatures, salinities, chlorophyll a concentra- tions and the zooplankton abundances. All the three jellyfish species showed great variations on both population abundance and distribution. The mean abundances of N. nomurai, C. nozakii, and A. aurita were 0--230.8ind/km2, 0--150.2ind/km2 and 0--123.4ind/km2, respectively. We also discussed the possible reasons of the three jellyfish species population dy- namics and the limitations of visual observation method in estimation of the scyphozoan jellyfish population abundance.