本研究針對黑潮上游與北南海海域單細胞固氮生物生物量之時空分布，及影響其分布之生態因子進行探討。在南海有文獻報告指出Trichodesmium及Richelia生物量遠比黑潮低，但南海水中N*值頗高，意謂應有頗活躍之固氮作用，究竟是否南海的固氮貢獻來自單細胞固氮生物的存在，過去在本研究海域無相關之報告可解明。本研究首次針對此海域單細胞固氮生物生物量進行有系統地探討。研究期間自2008年8月至2009年8月，共有四個航次，包括夏(CR1310及CR910)、冬(CR886)、晚春(CR899)三季，採樣測站在北緯21至22度，東經116至122度間，涵蓋黑潮及南海陸棚與海盆區。單細胞固氮生物之生物量為利用全細胞免疫化學染色法，以固氮酵素為抗體，進行抗原-抗體反應，偵測具有固氮酵素之單細胞生物，而後以顯微鏡計數其個數。單細胞固氮生物依體型分成四類型，即直徑為1-3 μm之圓形細胞(1-3 μm C)，直徑為1-3 μm之橢圓形細胞(1-3 μm R)，直徑為>3-10 μm之圓形細胞(>3 μm C)，直徑為>3-10 μm之橢圓形細胞(>3 μm R)。結果發現黑潮與南海表水單細胞固氮生物之生物量皆以冬季最高，夏季次之，晚春最低。比較不同類型單細胞固氮生物量的多寡，均以1-3 μm C最多，> 1-3 μm R次之，>3 μm R再次之，而>3 μm C最少。小體型的兩類細胞(1-3 μm C與1-3 μm R)生物量間有顯著正相關，大體型的兩類細胞(>3 μm C與>3 μm R)生物量間亦有顯著正相關，但小型細胞(1-3 μm C+R)與大型細胞(>3 μm C+R)生物量間無顯著相關。比較黑潮與南海表水間單細胞固氮生物之生物量，發現在夏季及晚春皆是南海比黑潮多，夏季在南海的生物量為黑潮的2倍，晚春時南海的生物量則為黑潮的1.3倍；冬季則是黑潮比南海稍多，黑潮的生物量為南海的1.2倍。1-3 μm C、>3 μm C、>3 μm R及大型細胞(>3 μm C+R)生物量皆與表水溫度呈顯著負相關。但表水溫度又與表水葉綠素a、[NO2+NO3]濃度、SRP濃度及N:P成顯著負相關。因此各類細胞與溫度間之關係可能伴隨其他生態因子之影響效應。1-3 μm C生物量分布可能主要受溫度的影響，溫度越低，生物量越高；但>3 μm C、>3 μm R及大型細胞(>3 μm C+R)的分布可能主要與磷的高低有關，磷酸鹽濃度越高，生物量越高。表水單細胞個體(包括固氮及非固氮生物)中，固氮生物佔60-90 %。單細胞固氮生物生物量之垂直分布，在夏季及晚春以深水層較表水多，冬季則是表水生物量高於深水。

Seasonal dynamics of unicellular diazotrophs were investigated in the upstream Kuroshio and the northern South China Sea (SCS). Unicellular diazotrophs had been postulated as an important N2-fixing contributor for the phenomenon of N* in the SCS where abundances of filamentous Trichodesmium and Richelia were scarced. Samples were collected during four cruises between August 2008 and August 2009 in summer (CR1310 and CR910), winter (CR886), and late spring (CR899), respectively. Sampling stations located between 21°N-22°N and 116°E-122°E in the upstream Kuroshio off southeast Taiwan and covering the shelf and basin waters of the northern SCS. The abundance of the unicellular diazotrophs was determined using whole-cell immunocytochemical method in which antibody of nitrogenase was used as the probe. Cells containing nitrogenase can be visualized and counted after the antigen-antibody reaction under microscope. Unicellular diazotrophs were classified to four types according to their sizes and shapes. For diameters of those with 1-3 μm and in coccoid shape are called 1-3 μm C, diameters of 1-3 μm and in rod shape are called 1-3 μm R, diameters of >3-10 μm and in coccoid shape are called >3 μm C, and diameters of >3-10 μm and in rod shape are called >3 μm R.
Surface abundance of the unicellular diazotrophs was highest in winter in both the Kuroshio and the SCS, followed by summer, and was least in late spring. Among four cell types, 1-3 μm C usually was the most abundant group, followed by 1-3 μm R and >3 μm R, and was least for the group of >3 μm C. The abundances between groups of 1-3 μm C and 1-3 μm R were positively correlated. Likewise, the abundances between >3 μm C and >3 μm R were positively correlated. However, the total abundance of small cells (1-3 μm C+R) was not significantly related to the large cells (>3 μm C+R). During summer and late spring, the abundance of unicellular diazotrophs in the SCS was 1.3-2 times of that in the Kuroshio. However, in winter the abundance in the Kuroshio was 1.2 times of that in the SCS. Surface water temperature was found negatively correlated to the abundance of 1-3 μm C, >3 μm C, >3 μm R, and large cells (>3 μm C+R), respectively. Significant correlations among surface water temperature and surface chlorophyll a, [NO2+NO3], SRP and N:P ratio implicated that the dynamics of cell abundances could be attributed to the correlated ecological variables of surface water temperature. The dynamics for the abundances of >3 μm C, >3 μm R, and large cells (>3 μm C+R) were suggested to relate with the fluctuation of SRP concentration. Unicellular diazotrophs accounted for 60-90 % of total unicellular cells in terms of cell number. Vertical distributions of unicellular diazotrophs in the Kuroshio and the SCS were in similar trends, with maximum abundance in deep water during summer and late spring, and on surface water during winter.

中文摘要…………………………………………………………………………… i
英文摘要…………………………………………………………………………… iii
第一章 前言……………………………………………………………………….. 1
第二章 文獻回顧………………………………………………………………….. 4
2.1 黑潮海域之地理環境與水文資料………………………………………. 4
2.2 單細胞固氮生物的細胞生物學……………………………………….… 6
2.3 單細胞固氮生物之重要性……………………………………….……… 8
2.4 單細胞固氮生物與環境因子之關係……………………………………. 11
第三章 材料與方法……………………………………………………………….. 16
3.1 水文資料測定與水樣採集………………………………………………. 16
3.2 <10 μm單細胞固氮生物之生物量分析………………………………… 17
3.3 營養鹽測定………………………………………………………………. 20
3.4 數據分析…………………………………………………………………. 21
第四章 預備實驗………………………………………………………………….. 22
第五章 結果……………………………………………………………………….. 23
5.1 夏季………………………………………………………………………. 23
5.2 冬季………………………………………………………………………. 28
5.3 晚春………………………………………………………………………. 31
5.4 不同季節之比較…………………………………………………………. 34
5.5 黑潮與南海區域比較……………………………………………………. 37
5.6 各類型固氮生物其生物量間的變動趨勢………………………………. 39
5.7 綜合全部數據看表水各類型單細胞固氮生物細胞密度與生態因子之關
係………………………………………………………………………….. 39
第六章 討論……………………………………………………………………….. 40
6.1 表水的分布………………………………………………………………. 40
6.2 垂直分布…………………………………………………………………. 43
6.3 單細胞固氮生物與生態因子之關係……………………………………. 44
參考文獻…………………………………………………………………………… 48

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