- 學位論文
東沙環礁之造礁珊瑚共生藻多樣性研究
Study on Symbiodinium diversity in scleractinian corals of Dong-Sha Atoll
摘要
東沙環礁為南中國海中最北端且發育完整的環礁。一九九八年的聖嬰現象造成的海水升溫，使得東沙環礁內的造礁珊瑚大量白化接續死亡。欲瞭解東沙環礁造礁珊瑚與其體內共生藻(以下合稱珊瑚共生體)的生物種系多樣性與組合、不同深度的分佈、以及其與溫度變化的相關性，以為未來擬定保育策略，特別是收集面對未來氣候變遷下的持續升溫，東沙環礁珊瑚共生體與珊瑚礁抵抗力與恢復力探討的基礎資料。 本實驗分別於2009與2010年在東沙環礁內的塊礁(Patch reef)之礁頂(Reef Top)和礁底(Reef Base)，採集了七科二十一屬，共九百零三株造礁珊瑚，利用聚合酶連鎖反應(PCR)放大共生藻的細胞核核糖體核酸大次單位(nlsrDNA)基因片段後，再利用限制性片段長度多態性(RFLP)分析來評估東沙環礁內造礁珊瑚體內共生藻的多樣性。結果顯示東沙環礁造礁珊瑚體內的共生藻主要為C系群與D系群。在2009年的771個樣本中，只與C系群共生的共生體為71.34%，只與D系群共生佔19.71%，同時與C和D系群共生為8.95%，此結果與印度太平洋其他珊瑚礁共生藻多樣性皆以C系群為主相似。進一步分析塊礁礁頂與礁底共生藻分佈，結果顯示礁頂共生藻D系群的比例24.48%顯著高於礁底共生藻D系群14.88% (chi-square, p=0.007)，這可能與礁頂年均溫較礁底年均溫高有關。在2010年因反聖嬰現象引發的白化事件中，白化珊瑚中，84.78%為C系群珊瑚共生體，D系群珊瑚共生體為10.87%，而未白化珊瑚其D系群珊瑚共生體比例為62.79%。顯示與D系群共生的珊瑚宿主可能可以抵抗因高溫引起的珊瑚白化。
並列摘要
Dong-Sha Atoll is the northernmost and well developed atoll in the South China Sea. For further study on reef-building corals and zooxanthellae (symbionts) diversity in coral hosts and their correlation with temperature fluctuation within different depths is necessary, to enact the conservation strategy in Dong-Sha Atoll, and important basic data to understand coral reef resistance and resilience to the gradual elevated seawater temperature caused by climate change. Coral samples were collected in 2009 and 2010 period in patch reefs of Dong-Sha lagoon from 2 different depths (Reef Top 1-5 meters and Reef Base 10–15 meters). A total of 903 samples belong to 7 families and 21 genera of reef-building corals were collected. Symbiodinium diversity was assessed using restriction fragment length polymorphism (RFLP) of the nuclear large subunit ribosomal DNA (nlsrDNA) of Symbiodinium DNA. In the present study, the results showed that the reef-building corals in Dong-Sha were associated with only two Symbiodinium clades: clade C and clade D. From the analysis of 771 samples collected in 2009, the Symbiodinium clade C, D and C+D proportion was 71.34%, 19.71% and 8.95% respectively. The results were similar to the pattern observed in corals from the Indo-Pacific where the Symbiodinium diversity of coral reefs is dominated by Symbiodinium clade C. Symbiodinium distribution analysis between Reef Top and Reef Base showed that clade D proportion in Reef Top (24.48%) was higher than Reef Base (14.88%)(chi-square, p=0.007). This might be due to the higher annual average seawater temperature at the Reef Top compared to Reef Base. In 2010 bleaching event caused by La Niña, the clade C proportion in bleached corals was up to 84.78% compared to clade D proportion of 10.87%. However, 62.79% of the non-bleached corals that were associated with clade D. This may support that Symbiodinium clade D can cope with coral bleaching caused by high seawater temperature.
參考文獻
延伸閱讀
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