中文摘要：

本文对南海北部SCS-N站（116°E，18°30’N，2016年5月）和菲律宾海西部PADST02-34站（129°59．7’E，17°29．7’N，2016年1月）真光层中颗石藻种群结构进行了对比。总体而言，南海北部真光层颗石藻丰度高于西菲律宾海，而物种多样性指数低于西菲律宾海，这与南海北部真光层中营养盐浓度高于同纬度西菲律宾海有关；两个海域颗石藻丰度极大值都出现在次表层，但在南海北部出现的深度要浅于西菲律宾海，这是由于南海北部真光层营养盐、温、盐跃层较西菲律宾海更浅。Florospheraprofunda是两个海域颗石藻种群的主要优势种，南海北部次级优势种为Emilianiahuxleyi和Gephyrocapsaoceanica，而西菲律宾海次级优势种则为Umbellosphaerairregularis。颗石藻属种的垂直分布构成在两个海域具有相似的特征，其中F．profunda主要分布在真光层中深层（〉80m）；G．oceanica和Gladiolithusflabellatus也主要出现在真光层中深层；Umbellosphaerairregularis，Syracosphaerapulchra，Helicosphaeracarteri和Discosphaeratubifera等则主要分布在100m以浅；E．huxleyi和Calcidiscusleptoporus在南海北部主要分布在i00m以浅，但在西菲律宾海则出现在深层（150m附近）。

英文摘要：

Community structures of living coccolithophores （LCs） in the euphotic zone at SCS-N station （116° E, 18°30＇ N, May 2016） in the northern South China Sea （NSCS） and PAC-ST02-34 station （129° 59.7＇ E, 17°29.7＇ N, January 2016） in the western Philippines Sea （WPS） were compared in detail in present work. Overall, the abundance of LCs was shown higher in the NSCS than that in the WPS, due to the higher concentration of nutri- ents in the euphotic zone in the NSCS . LCs abundance maximum appeared in the subsurface layer both in the NSCS and WPS, but it was shallower in the NSCS as a result of shallower nutricline, thermocline and halocline. Floro- sphera profunda was the predominant species in both areas, and Emiliania huxleyi and Gephyrocapsa oceanica were the secondary dominant species in the NSCS, while Umbellosphaera irregularis was the second dominant species in the WPS. Shannon-Wiener index of LCs in the NSCS was lower than that in the WPS, indicating relatively higher di- versity of LCs species in the more oligotrophic WPS. Similarities of vertical distribution of LCs species was shown in the NSCS and WPS= F. profunda, as a typical deep-water species, was mainly distributed at depth of 〉 80 m, and the same as G. oceanica and Gladiolithus flabellatus. Umbellosphaera irregularis, Syracosphaera pulchra, Heli cosphaera carteri and Discosphaera tubifera were mainly found at depth of 〈 100 m. E. huxleyi and Calcidiscus leptoporus were more abundant at depth of 〈100 m in the NSCS, however more common in the deep WPS （-150 m）.