Abstract:

Responses of Prochlorococcus (Pro),Synechococcus (Syn), pico eukaryotes (Euk) and heterotrophic bacteria (Bact) in pelagic marine ecosystems to external nutrient perturbations were examined using nitrogen (N), phosphorus (P),iron (Fe), and cobalt (Co) enriched incubations in the South China Sea in November 1997. Variations in abundance of the 4 groups of microorganism and cellular pigment content of the autotrophs during incubation were followed by flow cytometric measurements for seven days. During the incubation, Syn and Euk showed a relatively higher demand on Fe and N, while Pro required higher levels of Co and P. The Fe was inadequate for all the organisms in the deep euphotic zone (75 m) of the study area. The experimental results also implied that biological interaction among the organisms played a role in the community structure shift during the incubation. It seemed that besides the effects of temperature, there are some other physical and chemical limitations as well as impacts from biological interactions on Pro distribution in coast waters.

从营养扰动实验看原绿球藻在近海分布的制约因素
焦念志^1* 杨燕辉¹ Hiroshi KOSHIKAWA ²

（厦门大学海洋环境科学教育部重点实验室，厦门361005 2. National Institute for Environmental Studies, Tsukuba, Ibaraki 305-0053,Japan)

摘要： 地球上细胞最小、丰度最大的放氧光合自养原核生物原绿球藻（Prochlorococcus）发现于热带大洋，并被证实可在某些近海甚至近岸水域大量分布。但除温度之外，原绿球藻自然分布的控制因子尚不明了。从近海和大洋生态条件的主要差别考虑，在南海进行了主要营养盐———氮、磷和微量元素———铁、钴扰动的现场培养实验，并应用流式细胞技术监测原绿球藻及聚球藻（Synechococcus）、超微型真核浮游植物（pico-eukaryotes）的细胞丰度和单细胞色素含量的响应以及细菌的影响。结果表明，磷和钴的添加有利于原绿球藻，而氮和铁的添加更有利于聚球藻和超微型真核浮游植物。同时，由环境条件引起的生物响应又间接地导致超微型生物之间的相互作用。因而，原绿球藻在近海的分布，可能受到营养盐组成等环境因子以及生物之间的相互作用等多方面的限制和影响。
关键词： 原绿球藻；超微型浮游生物；营养盐；铁；钴；南海

通讯作者. E-mail: jiao @ xmu.edu.cn.

Key words: Prochlorococcus, picoplankton, nutrients, iron, cobalt, South China Sea