南海原核生物群聚結構的控制因子隨時空尺度之變異

The factors affect tempo-spatial variation of prokaryotic community structure at various scale in the South China Sea

柯叡澤(Jui-Tse Ko)

指導教授 ： 謝志豪

國立臺灣大學/理學院/海洋研究所/碩士(2021年)

https://doi.org/10.6342/NTU202102676

摘要

原核生物(prokaryotes)藉由物質循環影響海洋生態系，扮演重要角色。因此過往研究致力於調查影響原核生物群聚結構之因子，並顯示原核生物群聚的高變異性被多個環境因子影響，包含溫度、營養鹽、葉綠素和光線；但鮮少研究檢測群聚結構和環境的相關性是否受時空變化的影響。本篇研究於南海上相距330公里的兩個區域採集表層和葉綠素最大層之海水。同時，相同測站每三或六小時連續採集，持續兩天。以上步驟每年進行一次，共計三年（2016夏季、2017和2018秋季）。
　　本研究利用微生物體16S擴增子方法定序共計138個微生物樣本，以降趨對應分析(detrended correspondence analysis)和線性混合模式分析原核生物群聚結構、物種豐富度(richness)和環境間之相關性，以不同位置、深度和季節間變異作為隨機效應。
　　物種排序結果顯示原核生物的群聚結構、物種豐富度和溫度、無機氮、葉綠素濃度呈高度相關，其中，無機氮濃度對群聚結構的影響來自深度間變異，葉綠素濃度對群聚結構的影響來自季節間變異。再者，即使環境在兩日內變動不大，其因子仍影響群聚結構，但不影響物種豐富度。此結果說明區域效應(regional effect)，如季節、深度和位置，影響群聚結構和相對豐度，但在地效應(local effect)只影響群聚結構。不同原核生物的生態功能，如自營、異營作用，導致其群聚結構同時被區域效應和在地環境影響。最後，結果顯示單日內原核生物相具高變異性，因此本研究建議若欲比較不同季節間海洋原核生物相變化，單日多次採集為佳，否則其季節間和單日內變化量將難以合理比較。

關鍵字

原核生物群聚結構 ； 環境因子 ； 區域效應

並列摘要

The factors affecting marine prokaryotic communities are essential to study since prokaryotes crucially contribute to ecosystem functions. Previous studies have attributed community variation to various environmental factors; however, the comparison of factors across tempo-spatial scales (e.g., different sampling sites, depths, and time) is relatively scarce. Here, we collected prokaryotic communities from two sites that are 330 km apart and two depths, including the surface and the deep chlorophyll-a maximum (DCM; 35 to 80 m) layers, in the South China Sea. For each site, we collected prokaryotic communities every three (six) hours throughout two days, while the anchored diel sampling procedure was conducted in the summer of 2016 and the autumn of 2017, and 2018 to compare seasonal variation with daily variation.
　　A total of 138 prokaryotic communities were analyzed by using 16S rRNA gene-based amplicon sequencing. Community ordination was revealed by detrended correspondence analysis, and the relationships between community structure and diversity versus environmental factors were examined by linear mixed models after accounting for season, depth, and site effects.
　　The ordination results revealed an environmental gradient underlied community structure, particularly, temperature, dissolved inorganic nitrogen (DIN) and chlorophyll-a (Chla) could affect prokaryotic community sturcture and diversity. Among them, community-DIN relationship was driven by between-depth variation, while community-Chla relationship was driven by between-season variation. On the other hand, even though environmental factors exhibited low variation in two days, they were correlated to community structure; however, they exhibited no correlation with community diversity. In summary, regional effects (i.e., season, depth, and site) would cause community structure and diversity varying, while local environmental effects only change the community structure. We observed that prokaryotic community variation was caused by their functional difference. In addition, our findings suggest, to reliably examine changes in community structure across sampling seasons, multiple collections of community samples within a day may be needed.

並列關鍵字

Prokaryotic community structure ； Environmental factor ； regional effect

參考文獻

Azam, F. (1998). Microbial Control of Oceanic Carbon Flux: The Plot Thickens. Science, 280 (5364), 694.

Berry, D., Ben Mahfoudh, K., Wagner, M., Loy, A. (2011). Barcoded Primers Used in Multiplex Amplicon Pyrosequencing Bias Amplification. Applied and Environmental Microbiology, 77(21), 7846-7849.

Burson, A., Stomp, M., Greenwell, E., Grosse, J., Huisman, J. (2018). Competition for nutrients and light: testing advances in resource competition with a natural phytoplankton community. Ecology, 99(5), 1108-1118.

Chen, C. C., Shiah, F. K., Chung, S. W., Liu, K. K. (2006). Winter phytoplankton blooms in the shallow mixed layer of the South China Sea enhanced by upwelling. Journal of Marine Systems, 59(1), 97-110.

Chen, T. Y., Tai, J. H., Ko, C. Y., Hsieh, C. H., Chen, C. C., Jiao, N., et al. (2016). Nutrient pulses driven by internal solitary waves enhance heterotrophic bacterial growth in the South China Sea. Environ Microbiol, 18(12), 4312-4323.