黄海中华哲水蚤空间细结构分布特征及其影响机制研究

Yellow Sea Cold Water Mass is a typical hydrographic phenomenon in the Yellow Sea, where the major over-summering area of Calanus sinicus. The vertical distribution of Calanus sinicus may be affected by stable vertical structure of hydrology, temperature and subsurface chlorophyll maximum(SCM) according to the previous studies. Calanus sinicus adjust its movement in order to over-summering. The project focus on the adaptation of over-summering - Diel Vertical Migration (DVM), the sub-meter visualization analysis of vertical finestructure distribution, in order to explore the role and control factors in the process of over-summering in summer and introduce the mechanism of interpretation for over-summering details. The project will attend the multi-season voyage which cover the entire Yellow Sea Cold Water Mass, studying the temporal-spatial distribution and DVM of Calanus sinicus at finestructure in the Yellow Sea and those obtained by Video Plankton Recorder. The use of high precision, multi-parameter and in situ techniques to observe the finestructure changes of biological and environmental factors (including turbulence), consider the relationship between the vertical mixing intensity, SCM and DVM amplitude in order to illustrate ecological benefits by comparing the strong thermocline region and frontal area, which combined with the characteristics of spring and autumn. Studying on environmental and hydrological factors can improve the understanding of the driving factors, energy budget and population structure change of Calanus sinicus. The aim of the present study is to provide scientific basis for understanding the key life history strategy of Calanus sinicus.

黄海冷水团所在区域是桡足类优势种—中华哲水蚤的主要度夏场所。已有发现中华哲水蚤的垂向分布，可能受该海域稳定的水文垂向结构及温度和叶绿素最大层的位置影响，其通过调整自身移动模式以完成度夏过程。本项目聚焦度夏时的关键适应行为—昼夜垂直移动（DVM），力求推动中华哲水蚤的空间细结构分布格局对生物—物理因子响应的研究，阐明度夏细节并引入机制性解释。本项目将搭载相关航次，拟利用可视浮游生物记录仪（VPR），调查黄海冷水团区域中华哲水蚤的昼夜垂直分布和移动规律，运用高精度、多参数原位观测技术解析生物特征、环境因子的细结构变化及其耦合关系。通过夏季强跃层区和锋面区的对比，结合春、秋两季的时空特点，研究DVM幅度与垂向混合强度和叶绿素最大层等物理及生态因子之间的关系。本研究将有助于阐明中华哲水蚤度夏过程中昼夜垂直移动的驱动因素、能量收支及种群结构变化的过程，为充分理解中华哲水蚤的关键生活史策略奠定基础。

浮游动物的研究是海洋生态系统动力学研究中的核心问题之一，中华哲水蚤是黄海浮游动物关键种。本项目应用新的观测（高频、原位的光学观测）手段，试图将海洋动力过程与区域浮游动物优势种的分布相联系。夏季，通过初步分析采集时间、温跃层强度变化、叶绿素最大层深度与营养盐跃层等相关信息，发现叶绿素最大层位置和强度受温跃层强弱影响，常分布在温跃层内部或下方；叶绿素最大层可以是中华哲水蚤度夏期间的重要食物来源，满足其摄食需求，并规避表层高温的伤害。营养盐跃层附近引起浮游植物生长率的提高称为SCML（Subsurface Chlorophyll Maximum Layer）的形成机制。中华哲水蚤夏季主要分布在黄海冷水团海区的底部或近底部，由于底部水域水温较低、食物较匮乏，生物个体往往会降低其发育率和生殖能力以适应现有的环境条件。多次现场观测发现中华哲水蚤在温跃层内的SCM层出现，推断傍晚到清晨期间，温跃层附近出现叶绿素最大层，为中华哲水蚤进入温跃层进行短暂的摄食提供了便利的条件。温度和饵料适宜时，溶解氧与水深也是其分布应考虑的因素。当环境适宜同时由于能量摄入的需要，跃层附近丰富的饵料是植食性桡足类上升，进而摄食满足自身能量需求的重要影响因素。因此，对于桡足类来说，在夜间短暂停留在SCM层中可能是一个综合权衡的选择。