黄海太平洋磷虾的幼体分布及发育途径

SPATIAL DISTRIBUTION OF LARVAE AND LARVAL DEVELOPMENT OF EUPHAUSIA PACIFICA IN THE YELLOW SEA

通过镜检分析网采样品和现场培养实验相结合的方法,研究了2006年4月份黄海太平洋磷虾的幼体分布、早期幼体发育和幼体发育途径。结果表明,4月份是南黄海太平洋磷虾繁殖发育的高峰期,幼体在种群组成结构中占绝对优势,占种群总数量的90.85%,其中原状幼体和状幼体占种群比例分别是51.9%和26.9%。相关性分析结果表明,太平洋磷虾不同幼体发育期丰度存在显著的正相关关系;卵丰度分布跟叶绿素a浓度有显著的正相关关系;原状幼体和状幼体丰度分布跟叶绿素a浓度、海水温度等环境因子没有显著相关关系。在南黄海,太平洋磷虾的幼体发育主要遵循以下途径:卵→无节幼体→后期无节幼体→原状幼体→状幼体F1(0′7,1′7)→状幼体F2(1′4″7,3′1″7)→状幼体F3(5″7)→状幼体F4(5″5)→状幼体F5(5″3)→状幼体F6(5″1)。太平洋磷虾在15℃下的幼体发育速度明显快于4℃。15℃下幼体发育到C1期只需5.6天,而4℃下则需要16.1天。

As one of six important Euphausiids species being commercially harvested, Euphausia pacifica Hansen is widely distributed in the North Pacific Ocean and its adjacent coastal waters. E. pacifica is the dominant zooplankton species and functional group in the Yellow Sea and is regarded as one of the most important zooplankton species and functional group in the Yellow Sea ecosystem in China-GLOBEC （China-Global Ocean Ecosystem Dynamics） program by virtue of its great abundance, large body size, and the significant role it plays in the marine food chains. We believe that the changes in distribution and abundance of E. pacifica could directly influence the whole Yellow Sea ecosystem. Study on spatial distribution of E. pacifica larvae and its larval development in the Yellow Sea shows that, E. pacifica population recruited vigorously in April, of which the larvae dominated （90.85% of the population）. Egg abundances were positively correlated with chl a concentration. Frequencies of furcilia developmental forms did not related to environmental factors （seawater temperature and chl a concentration）. Adults preferentially spawned and reproduced in the sea areas of high chl a concentration. The larvae developmental pathway was ascertained from net samples collected in the southern Yellow Sea in the sequence of egg→nauplius→metanauplius→calyptopis→furcilia F1（0′7,1′7）→furcilia F2（1′4＂7,3′1″7）→furcilia F3（5″7）→furcilia F4（5″5）→furcilia F5（5″3）→furcilia F6（5″1）. Early larval development of E. pacifica was observed under controlled condition in laboratory. The development of E. pacifica larvae took obviously a longer time in 4℃ than in 15 ℃. Eggs can be successfully developed into stage C 1 within 5.6 days in 15℃, but 16.1 days in 4℃.