本研究針對南海北部海域超微浮游植物（Picophytoplankton），包括原核綠球藻（Prochlorococcus）、聚球藻（Synechococcus）及超微真核藻類（Picoeukaryotes）細胞數量之季節變化及空間分布進行探討，並利用培養實驗（光線及營養鹽）探討影響其生長的主要因子為何。調查於2004年2月到2005年1月，共進行7航次，涵蓋13測站的採樣。所採集樣品以流式細胞儀（flow cytometer）分析計數三類超微浮游植物。
結果顯示南海中Synechococcus細胞密度約在1×104 cells ml-1左右。冬季所有測站平均（1.37±0.30×104 cells ml-1）顯著比夏季及秋季者（分別為0.51±0.13×104 cells ml-1及0.54±0.22×104 cells ml-1）高。相同季節中Synechococcus細胞密度以陸棚-坡區較海盆區高；夏季 Synechococcus細胞密度與表水營養鹽濃度呈現正相關，相對的冬季細胞密度與表水營養鹽濃度無相關，且冬季添加硝酸鹽後對其成長並無幫助，顯示夏季細胞密度低可能是由於夏季營養鹽缺乏。另由光強度控制實驗，顯示Synechococcus可能在光線充足的環境中會有較好的生長，此由垂直分布上呈現表水細胞數量往往不低，細胞數量最大值多出現在表層或次表層水，且此最大值水深在冬季比夏季淺等可知。冬季表水在添加鐵後，Synechococcus細胞數量顯著增加，顯示南海冬季時可能受到鐵的限制。
Picoeukaryotes細胞密度全年皆在0.5×104 cells ml-1以下。冬季所有測站平均（0.46±0.10×104 cells ml-1）比夏季及秋季者高（分別為0.15±0.02×104 cells ml-1及0.19±0.03×104 cells ml-1）。相同季節中Picoeukaryotes細胞密度以陸棚-坡區比海盆區高，尤其冬季的陸棚-坡區（0.70±0.11×104 cells ml-1）為最高。冬季時細胞密度與表水營養鹽濃度均呈現正相關，但培養實驗中，添加硝酸鹽及鐵對其皆無顯著的影響。
本研究有關Prochlorococcus之分布因使用流式細胞儀FL3 PMT時，加速電壓設定不同，只採用冬季（OR1-743航次）之數據。Prochlorococcus垂直分布顯示在有光區內細胞數量皆在5.5×104 cells ml-1以上，最深分布可達200公尺深。光強度控制實驗結果顯示，表水者比深水者對於較強光線有較好的生長能力，深水者可以在較低的光強度中生長。此外深水樣品中培養於透光度9%下之Prochlorococcus仍能生長，此說明Prochlorococcus垂直分布上可分布至較深的現象。另外從添加培養實驗中發現冬季的Prochlorococcus在添加硝酸鹽或鐵後，成長不會被促進。

This research investigated the seasonal and spatial distributions of picophytoplankton, including Prochlorococcus, Synechococcus and picoeukaryotes, in the northern South China Sea. Monitoring experiments including light intensity control and nutrient enrichment were conducted concurrently with on board sampling to examine factors affecting their cell densities dynamics. Quantification of cell numbers was carried out by flow cytometry. Averaged Synechococcus abundance in the South China Sea was 1×104 cells ml-1, high in winter (1.37±0.30×104 cells ml-1) and low in summer or fall (0.51±0.13×104 cells ml-1 and 0.53±0.22×104 cells ml-1, respectively). During a same season of the year, there was more Synechococcus in the shelf-slope region than in the basin. The cell density in summer, but not in winter, was significantly positively related to surface water nutrient concentration. Nutrient enrichment experiment carried out in winter also indicated that the growth of Synechococcus did not respond to addition of nitrate. On the other hand, Synechococcus seemed to prefer high illumination. In the light intensity experiment, Synechococcus collected from surface water grew better at 100% surface illumination than <100% light intensities. Synechococcus collected from deep water grew best at 30% and 18% of surface illuminations. Vertically, Synechococcus concentrated mostly in surface water with maximum cell number occurring at the surface or a few meters deep. Nutrient enrichment experiment in winter also showed that Synechococcus responded significantly to iron addition.
Average cell density of picoeukaryotes was always less than 0.5×104 cells ml-1, being high in winter (0.46±0.10×104 cells ml-1) and low in summer or fall (0.15±0.02×104 cells ml-1 and 0.19±0.03×104 cells ml-1, respectively). Picoeukaryotes was always more concentrated in the shelf-slope region than in the basin, especially in winter when cell density in the shelf-slope region was 0.70±0.11×104 cells ml-1. Although in winter picoeukaryotes was significantly positively related to surface water nutrient concentration, enrichments of nitrate or iron did not enhance their growth.
Prochlorococcus had a cell density > 5.5×104 cells ml-1 in the euphotic zone, and distributed as deep as 200 m. Light intensity monitoring experiment showed that Prochlorococcus from surface water grew better under high illumination than those from deep water and vice versa. Under 9% of surface illumination, deepwater Prochlorococcus population showed a positive growth, corresponding well with its deep distribution. Nutrient enrichment experiment conducted in winter showed that Prochlorococcus did not respond to enrichment of nitrate or iron.

目錄
章次 頁數


中文摘要…………………………………………………………………… I
英文摘要…………………………………………………………………… III
目錄………………………………………………………………………… V
表目錄……………………………………………………………………… VI
圖目錄……………………………………………………………………… VII
附錄目錄…………………………………………………………………… VIII
壹、前言……………………………………………………………………… 1
貳、文獻回顧………………………………………………………………… 3

陸、參考文獻
（本論文英文文獻採用Deep-Sea Research I之格式）
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韓舞鷹，1998。南海海洋化學，科學出版社，共289頁。
梁文德，2002。南海上層海溫及海流變化之研究，博士論文，國立台灣大學海洋研究所，共127頁。
廖嘉文，2003。台灣附近海域聚球藻（Synechococcus）生長率受到營養鹽種類限制之研究，碩士論文，國立海洋大學海洋生物研究所，共50頁。
Agawin, N.S.R., Carlos, M.D., Agust