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Diel variation of community composition in photosynthetic picoeukaryotes in the northeastern coastal water of Taiwan in warm season
|Authors: ||Liu, Wei-Ting|
|Issue Date: ||2017-11-15T08:45:45Z
|Abstract: ||超微真核藻類(cell size < 3 μm)的多樣性相當高，包含有綠藻 (Chlorophyte)、著鞭毛藻 (Haptophyte) 與隱藻 (Cryptophyte)等，是海洋中重要的基礎生產者。先前的研究指出超微真核藻類的數量有日夜變化，但目前對於造成日夜變動的種類為何並不清楚。本研究利用色素分析(< 20 μm)、18S DNA定序與螢光原位雜合法與來研究台灣東北沿岸超微真核藻類數量日夜變化與其種類組成。研究結果顯示，色素分析中綠藻的特徵色素chlorophyll b (Chl b) 濃度有日夜周期變化並且Chl b濃度與超微真核藻類數量有正相關，代表含Chl b之物種可能是超微真核藻類的重要貢獻者。18S rDNA定序結果顯示，白天與晚上的種類組成大不相同，白天時段大多以矽藻為主，晚上時段，Mamiellophyceae (綠藻門) 的比例會大幅增加，包含有Micromonas和Ostreococcus。螢光原位雜合法結果顯示Mamiellophyceae平均佔超微真核藻類數量的 90% 以上。七月與八月以Micromonas為主，而九月以Ostreococcus為主。以上的結果顯示超微真核藻類數量的日夜變化主要是由Mamiellophyceae所造成，代表他們對於沿岸生態系中的碳循環佔有重要地位，未來可進一步對優勢族群進行能量傳遞之評估。|
Photosynthetic picoeukaryotes (PPEs, < 3μm) are highly diverse, comprising chlorophytes, haptophytes and cryptophytes, and so on. Also, they are abundant in the ocean, playing an important role as primary producers in the ocean. Previous studies have pointed out that a diel variation of picoeukaryotes abundance existed, but little is known about what PPEs were responsible for diel variation. In this study, we try to understand the diel variation of PPEs regarding to their abundance and community in the northeastern coastal water of Taiwan based on the High-Performance Liquid Chromatography (HPLC), 18S rDNA clone libraries and Tyramide Signal Amplification - Fluorescent In Situ Hybridization (TSA-FISH). The HPLC results showed that there is a diel variation on Chl b concentrations which was correlated with PPE abundances, implying that Chl b concentrations were mainly contributed by PPEs. The result of 18S rDNA clone libraries showed that PPE community composition was distinct between day and night, and diatom sequence was dominant in daytime. At night, Mamiellophyceae sequences containing Micromonas and Ostreococcus. The results of TSA-FISH showed that Mamiellophyceae (Chlorophyta) accounted for > 90% of PPE abundance. In Mamiellophyceae, Micromonas was dominant in July and August while Ostreococcus was dominant in September. The above results showed that the diel variation of PPE abundance was caused by the Mamiellophyceae implying their importance on carbon cycles in a coastal ecosystem. In the future, energy flow in dominant population is worth to evaluate.
|Appears in Collections:||[海洋環境與生態研究所] 博碩士論文|
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