南海北部中华哲水蚤动物地理学研究及其对环境的响应

Calanus sinicus, the dominant species of planktonic copepod in the continental shelf waters of China. And it is also the key species in the structural and functional research on ecological system in China's offshore. Previous research showed that the C. sinicus is carried into the Taiwan Strait from population centers in the East China Sea by the China Coastal Current during the northeast monsoon period in winter. C. sinicus was transported from the East China Sea to the northwest continental shelf of South China Sea by the Guangdong Coastal Current, which was driven by the northeast monsoon in spring. The presence of coastal upwelling driven by the southwest monsoon provided suitable survival conditions for C. sinicus in summer. This species disappeared in autumn due to high temperatures and did not begin to enter into the northwest continental shelf of South China Sea from the East China Sea during the period of investigation in winter. However, recent study found that neither population recruitment from the East China Sea nor the provided protection from cold eddy and upwelling, there are still having C. sinicus in the northwest continental shelf of the South China Sea. Compared with C. sinicus in the Yellow Sea and East China Sea, if there is Geographical differentiation on C. sinicus in the northern South China Sea? How much does ocean currents transport and local supplement make relative contribution to the C. sinicus populations supplementary in the South China Sea? Based on the analysis and calculation of the gene sequences, we will discuss the genetic diversity, population genetic structure among China seas. Meanwhile, population differentiation, population recruitment and life history strategy of C. sinicus in the northern South China Sea will be analysised. We aim to find out the molecular evidence to population differentiation of C. sinicus in the northern South China Sea, and to reveal the essential physical processes influencing on their recruitment mechanism and life history strategy, which is important for the study of population dynamics of C. sinicus.

中华哲水蚤作为我国近海浮游桡足类优势种，是近海生态系统结构和功能研究的关键种。以往研究表明，东北季风盛行的秋冬季浙闽沿岸流携带东海的中华哲水蚤进入台湾海峡，在翌年春季抵达南海西北部海域，夏季沿岸的上升流为其提供了避难所，秋季这些海域的中华哲水蚤随上升流的消失和水温升高而消失，在秋冬季节南海北部没有中华哲水蚤。而最近研究显示，在既没有东海种群输送也没有上升流提供保护的情况下，南海北部依然有中华哲水蚤分布。南海与中华哲水蚤的主要分布区黄东海的环境差异较大，那么与黄东海中华哲水蚤相比，南海北部中华哲水蚤是否存在地理分化？海流输送和本地补充在南海北部中华哲水蚤种群补充中相对贡献是怎样的？针对上述问题，本项目从中华哲水蚤的遗传多样性研究入手，揭示不同地理种群之间的遗传差异以及在不同环境条件下种群分化的遗传学证据，探讨其在南海北部的生存策略和种群补充机制，为中华哲水蚤的种群动力学等研究提供科学依据。

本项目采集和整理我国沿岸中华哲水蚤样品，利用传统的形态分析研究方法与分子生物学方法相结合对中华哲水蚤不同地理种群之间的遗传多样性进行分析和研究，发现这些海域的种群之间无明显的群体隔离，六个区域大部分测得的序列是无差异的，但是粤东粤西采集的样品变异程度更大。虽然南海北部中华哲水蚤可能存在一定程度的本地补充，但由于中国沿岸流的运输，南海北部中华哲水蚤除了本地补充，应该还存在大量的外源性输入补充。同时通过对南海北部中华哲水蚤的调查以及整理历年来调查数据和资料，发现中华哲水蚤在南海北部四个季节都出现过。4月份以后，南海北部在没有得到黄东海种群补充的情况下依靠自身繁殖维持种群丰度，这是因为夏季西南季风期间，粤东上升流、雷州半岛东部的冷涡和琼东沿岸上升流为中华哲水蚤提供了庇护。中华哲水蚤在南海北部的丰度与南海北部的上升流出现和消亡的时间，上升流的强弱程度等有很大关系。本研究探讨了中华哲水蚤在南海北部的生存策略和补充机制，为南海北部中华哲水蚤的种群动力学研究提供了科学依据。