Plankton Ecological Processes in Subtropical-Shelf Ecosystems: Dissolved Primary Productivity and Its Passive Leakage Model in the East China Sea(I)

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Project title

Code/計畫編號

MOST107-2611-M019-010

Translated Name/計畫中文名

子計畫：副熱帶陸棚浮游生物食物網生態過程研究-東海溶解態基礎生產力及其被動釋放機制探討(I)

Project Coordinator/計畫主持人

Tzong-Yueh Chen

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=12673136

Year

2018

Start date/計畫起

01-08-2018

Expected Completion/計畫迄

31-07-2019

Bugetid/研究經費

1206千元

ResearchField/研究領域

海洋科學

"溶解態基礎生產力 (DPP) 是微生物環的主要驅動者之一，可提供異營性細菌的有機碳需求 (BCD) 高達100%。在全球暖化議題的驅動下，科學家們長期以來一直偏重於顆粒態基礎生產力 (PPP) 在海洋有機碳通量上的研究，而較少關注溶解態基礎生產力在海洋微生物生態系的角色。然而，很多證據顯示溶解態基礎生產力會隨著總基礎生產力 (TPP=DPP+PPP) 的升高而增加，但其胞外釋放比 (PER; =DPP/TPP )，也就是溶解態基礎生產力佔總基礎生產力的比例卻是隨之下降。這暗示著在低生產力的環境下，浮游植物會釋出較高比例的溶解態有機碳。因此，本研究延續過去計畫提出的假設：「在低生產力的環境下，微生物環傳遞光合作用有機碳的角色可能遠比我們現在的認知更為重要」，收集更多支持的證據。再者，過去對於為何浮游植物會釋放溶解態有機碳，科學家們也提出了一些可能的機制，本研究同時將檢視被動釋放機制 (擴散作用) 在東海是否適用。現階段對溶解態基礎生產力的研究多集中在極區、大西洋及地中海，而臺灣所處的西太平洋地區則自上年度計畫起，本人開始進行溶解態基礎生產力的調查。東海是個同時具有貧養、中養及優養的系統，亦即具有很高的生產力梯度，因此推測可能也會有很高的PER梯度，自然成為一個絕佳測試假說的試驗場所。在本研究中，將進行顆粒態與溶解態基礎生產力 (不同浮游植物大小)、異營性細菌生產力 (BP)、細菌呼吸率 (BR)、異營性細菌生物量 (BB)、溶解態與顆粒態有機碳 (DOC & POC) 、葉綠素甲 (不同尺寸浮游植物) 與無機營養鹽的量測，將可對東海光合作用有機碳分別進入攝食食物網與微生物環的比例有量化的估計。本研究屬多年期計畫，將於三年內達成五大目標：1. 延續定量溶解態基礎生產力及其在東海的空間分佈。2. 延續定量溶解態基礎生產力佔總基礎生產力的比例及其在東海的空間分佈。3. 延續定量溶解態基礎生產力對異營性細菌碳需求 (BCD=BP+BR)4. 定量溶解態基礎生產力及其相關參數在東海的季節性變化。5. 驗證擴散作用是否為東海溶解態基礎生產力的重要機制。" "Dissolved primary productivity (DPP; i.e. phytoplankton extracellular released dissolved organic matter) is considered an important driven force for the microbial loop, which contributes up to 100% of heterotrophic bacterial carbon demand (BCD) in the ocean. Under global warming scenario, researchers have paid much attention on the cycling of particulate primary productivity (PPP) in the past decades, whereas the DPP contribution on organic carbon cycling is usually omitted or estimated as a rough fraction. However, the dynamics of DPP, which represents the proportion of total primary productivity (TPP; TPP=DPP+PPP) entering the microbial loop, may significantly regulate the carbon flux within the microbial loop. The knowledge of DPP is relatively limiting. Previous studies have addressed that DPP is positively related to TPP. However, the percent extracellular release (PER; defined as DPP/TPP) is negatively related to TPP, indicating phytoplankton releases higher fractions of DPP in low TPP conditions. Therefore, a hypothesis in previous proposal has been postulated that microbial loop may play a more important role in the transport of photosynthetically fixed carbon in low TPP environments than we thought before. There are few mechanisms that explain how phytoplankton release dissolved organic carbon (DOC) to the surroundings. In this proposal, I will test how passive leakage model (diffusion) is applicable to DPP in the East China Sea (ECS). To date, most DPP studies have been conducted in the Atlantic Ocean, Mediterranean Sea, and Polar Regions. I just initiated DPP survey in the western Pacific and ECS. The ECS might be an excellent area for the hypothesis test due to the wide range of nutrient conditions (from oligotrophic to eutrophic), therefore primary productivity. In this study, determinations of PPP and DPP (in different size of phytoplankton communities), heterotrophic bacterial production (BP) and respiration (BR), heterotrophic bacterial biomass (BB), DOC and particulate organic carbon (POC), chlorophyll-a concentration (in different size), and inorganic nutrients will be conducted. This proposal will be a multi-year study and will be able to quantify how much photosynthetically produced carbon transported in the grazing food webs and the microbial loop in the ECS. Five objectives will be accomplished in 3 years:1. To continue to quantify the DPP and to identify its spatial distribution in the ECS.2. To continue to quantify the PER and to identify its spatial distribution in the ECS.3. To continue to quantify the contribution of DPP to heterotrophic bacterial carbon demand (BCD; defined as BP+BR) in the ECS.4. To quantify the seasonal variation of DPP and its related parameters in the ECS.5. To testify if the passive leakage (diffusion) model is applicable to DPP in the ECS."

Keyword(s)

溶解態基礎生產力
顆粒態基礎生產力
胞外釋放百分比
異營性細菌生產力
細菌呼吸率
細菌碳需求
Dissolved Primary Productivity
Particulate Primary Productivity
Percent Extracellular Release
Heterotrophic Bacterial Production
Bacterial Respiration
Bacterial Carbon Demand

DSpace CRIS

Plankton Ecological Processes in Subtropical-Shelf Ecosystems: Dissolved Primary Productivity and Its Passive Leakage Model in the East China Sea(I)

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