南海北部不同粒级浮游动物氮稳定同位素研究

Stable nitrogen isotope of size fractionated zooplankton in northern South China Sea

在2015年夏季和冬季开展了南海北部海域不同粒级浮游动物生物量和氮稳定同位素特征的研究。按照浮游动物粒径大小将其分成3个类群,即小型浮游动物(180~380μm)、中型浮游动物(380~500μm)和大型浮游动物(>500μm)。结果显示浮游动物生物量和氮稳定同位素空间分布差异明显,高值区多分布于珠江口、东沙群岛和台湾海峡南部海域。浮游动物氮稳定同位素δ^(15)N值出现显著的季节和粒径结构差异,其中夏季δ^(15)N平均值高于冬季,以小型浮游动物尤为明显(P<0.01)。各粒级浮游动物δ^(15)N值随粒径增大而增加。小型和中型浮游动物δ^(15)N值与浮游动物生物量有显著的相关性,而大型浮游动物与浮游动物生物量则关系不明显。

The stable nitrogen isotope and biomass of zooplankton based on size fractionation were studied in the northern South China Sea during summer and winter, 2015. The zooplankton was divided into three groups according to size structure, i.e., micro-zooplankton （180～380 μm）, meso-zooplankton （380～500 μm） and macro-zooplankton （〉500 μm）. The results show that significant spatial difference exist between zooplankton biomass and stable nitrogen isotope. And high values appeared around the Pearl River estuary, Dongsha Islands and south Taiwan Strait. The mean δ^15N value of zooplankton in summer was higher than that in winter, especially that of the micro-zooplankton （P〈0.01）, and the δ^15N value of size-fractioned zooplankton generally increased from small to large size zooplankton. The correlation analysis shows that both the δ^15N value of micro- and meso-zooplankton are closely related to zooplankton biomass, while the δ^15N value of macro-zooplankton is not.