南海北部夏、冬季今生颗石藻分布

Distribution of living coccolithophores in the northern South China Sea in summer and winter

本研究对2009年南海北部（17°~24°N,108°~122°E）夏季和2010年冬季的颗石藻群落结构进行了描述。颗石藻镜检工作以偏光显微镜为主,并辅助于扫描电镜进行物种的鉴定与计数,共鉴定物种11属13种。总体来说,冬季的颗石藻细胞丰度明显高于夏季,夏季细胞丰度介于0.3×103~71.8×103 cells/L之间,平均丰度6.0×103 cells/L;冬季介于0.3×103~64.4×103 cells/L之间,平均丰度6.7×103 cells/L。夏季多样性指数和均匀度指数分别介于0.30~1.98和0.30~0.99之间,冬季分别介于0.51~2.25和0.33~0.99之间。夏季颗石藻细胞表层丰度分布规律不显著,冬季颗石藻分布高值区位于珠江口的外海站位;垂直分布上,颗石藻细胞丰度高值通常出现于次表层水体。调查期间颗石藻类群出现的优势种为纤细伞球藻（Umbellosphaera tenuis（Kamptner）Paasche）、赫氏艾密里藻（Emiliania huxleyi（Lohmann）Hay et Mohler）以及大洋桥石藻（Gephyrocapsa oceanica Kamptner）。典范对应分析（Canonical Correspondence Analysis,CCA）结果表明,夏季优势种赫氏艾密里藻和大洋桥石藻与大部分环境因子呈正相关关系,冬季响应特征不同。

According to the samples taken from the northern South China Sea（17°-24°N,108°-122°E）during 2009 summer and 2010 winter cruise living coccolithophores（LCs）community structure were statistically studied.The LC samples were identified under polarizing microscope,associated with scanning electron microscope（SEM）dealing with the uncertain taxa.A total of 13 taxa belonging to 11 genera were identified.The LCs cell abundance ranged 0.3×103-71.8×103 cells/L in the summer cruise with an average 6.0×103 cells/L,and ranged 0.3×103-64.4×103 cells/L in the winter cruise with an average 6.7×103 cells/L.The Shannon-Wiener index of LCs in summer and winter were ranged from 0.30-1.98 and 0.51-2.25,respectively,and Pielou evenness index were ranged from 0.30-0.99 and 0.33-0.99,respectively.The LCs cell abundance was higher in winter than that in summer.In winter LCs abundance was more prevailing in the deep basin as compared to that in the continental shelf,while in summer it was not in that case.Vertically,high cell abundance of LCs were typically distributed in the sub-surface layer.Umbellosphaera tenuis（Kamptner）Paasche,Emiliania huxleyi（Lohmann）Hay et Mohler and Gephyrocapsa oceanica Kamptner were predominant species in both cruises.E.huxleyi and G.oceanica were positively correlated with the main environmental factors indicated by canonical correspondence analysis（CCA）in summer,nevertheless,the responsing characters varied in winter.