Investigating the Impact of Global Change on the Ecosystem and Environmental Conditions in the East China Sea and Kuroshio Region on Microbial Carbon Flux---Viral Lysis and Nanoflagellate Grazing

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Project title

Code/計畫編號

NSC102-2611-M019-009-MY2

Translated Name/計畫中文名

全球變遷對西北太平洋臺灣海域海洋生物地球化學與生態系統影響之長期觀測與研究(I)－子計畫：全球變遷因子對東海及西北太平洋黑潮海域微生物循環圈能量傳遞的影響－病毒裂解與微細鞭毛蟲攝食

Project Coordinator/計畫主持人

An-Yi Tsai

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Institute of Marine Environment and Ecology

Website

https://www.grb.gov.tw/search/planDetail?id=8106007

Year

2014

Start date/計畫起

01-08-2014

Expected Completion/計畫迄

01-07-2015

Bugetid/研究經費

1485千元

ResearchField/研究領域

海洋科學

"在海洋環境中基礎生產力約有50%的有機碳經同化作用被異營性細菌所利用.而異營性細菌則是扮演著控制微生物環之能量及物質循環的重要角色,據研究了解到異營性細菌的生產量是受到生物及非生物因子所影響. 非生物因子包括溫度,鹽度及有機物質的利用(bottom-up control). 而生物因子則透過原生動物的攝食與病毒裂解 (top-down control)的過程而有效控制異營性細菌的生產量.在能量的傳遞上,細菌如被原生動物攝食會將能量往上一階傳遞,如細菌被病毒所裂解其微生物環的能量會繼續在水體中循環,進而快速地被異營性細菌所利用.因此了解原生動物的攝食與病毒裂解的重要性,可讓我們更深入探討水體中能量流動的方向.本研究的海域---東海位於西北太平洋的西部邊緣海域,其中除長江沖淡水會注入陸源性物質及營養鹽會影響此海域物理化學與生物空間變化外,尚還有來自東海北方的黃海水,東海東邊貧養鹽之黑潮水與入侵東海南邊的台灣暖水.直到現在,對現今的研究而言,在東海海域環境中病毒與微細鞭毛蟲攝食對細菌數量及能量傳遞的影響尚未有完整的資料報導過. 本研究計畫的目的則是希望利用修正後之稀釋培養法(modified dilution method) 同時測量到病毒與上階攝食者(如微細鞭毛蟲)對東海海洋不同生態環境中之細菌生產量所產生的影響,據此可進一步了解病毒與原生動物攝食者對東海海域之細菌所扮演的生態角色." "Heterotrophic bacteria assimilate a significant fraction of the primary production (approximately 50%) in marine environments. Bacterial production is dependent on both abiotic and biotic factors. Abiotic factors (bottom-up control) include temperature, salinity and substrate availability. The biotic factors (top-down control) that may control bacterial production in aquatic systems are predation by protists as well as viral infection and lysis. When bacterial cells are grazed, energy is made available to higher trophic levels, whereas when they are lysed, organic carbon and nutrients are dissolved and bacterial carbon is recycled as bacterial production in a closed loop. Therefore, it is important to estimate both viral- and grazing-induced bacterial mortality to obtain better insight into the forces underlying nutrient flow within an aquatic food web. The East China Sea (ECS) is located on the western edge of the Northwest Pacific Ocean, and is characterized by dynamic interactions among water systems including nutrient enriched freshwater input from the Changjiang River. In addition to freshwater input from Changjiang River, there are three other water masses which influence the ECS: the Yellow Sea Coastal Water (YSCW) from north to south along the northwest coast of the sea, the Kuroshio Water (KW) coming from the western equatorial Pacific in the east and Taiwan Current Warm Water (TCWW) from the south. To date, no studies have investigated the effect of viral-mediation of bacterial production in the ECS. In this study, we estimated grazing and viral mortality of bacteria with the used of the modified dilution approach to compare the relative contributions of viral lysis and nanoflagellate grazing on bacterial mortality and explore the variation in these loss factors in the ECS."

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Investigating the Impact of Global Change on the Ecosystem and Environmental Conditions in the East China Sea and Kuroshio Region on Microbial Carbon Flux---Viral Lysis and Nanoflagellate Grazing

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