Abstract
摘要:高屏峽谷向上連接源自玉山的高屏溪,向下匯至超過五千公尺深的馬尼拉海溝,因地震、強降雨引發的海底濁流,複雜地形引發的強烈內潮,高屏峽谷已成為國際知名沉積物源匯過程及海底地質災害的自然實驗室。過去我們發現內潮在高屏峽谷引發的強烈底流,不但直接降低生物數量、多樣性及改變生物組成,也掏選有機質較低的粗顆粒泥沙,進而減少食物供給,再間接影響生物數量及多樣性。而本計畫將沿續過去的成果,利用高屏峽谷內外強烈對比的物理環境及底棲生物群聚結構,進一步探討底棲生物在高輸砂量峽谷碳循環中所扮演的角色。
我們預計分年分區建立高屏峽谷及斜坡上、中、下部有機碳循環模式,主要執行步驟如下: (1)測量底棲生物及沉積物有機碳含量;(2) 測量(如沉積物群聚耗氧量)或使用文獻資料(如顆粒有機碳通量、有機碳埋藏量等)來估計各碳庫(stocks)間的源匯通量(carbon flows);(3) 假設穩定狀態,以線性逆模型(Linear Inverse Model)推估碳庫間未知的通量及掠食關係。為了估計模式中的參數,我們將發展新的觀測技術,例如以深海著陸器觀測沉積物群聚呼吸率、營養鹽再生、海床水文及流速資料,以錨錠攝影機及陷阱拍攝或捕捉底棲生物。除此之外,我們也將同步進行傳統的沉積物採樣、培養、水文觀測以及底拖網採集,並用現場(in-situ)觀測資料來驗證船載(ship-board)的測量資料。
物質或能量在不同食階或環境間的轉換為生態系最重要的功能,透過觀測或模式估計,本計畫將提供台灣西南海域基礎底棲生態系功能及生物多樣性資料。這些資料將幫助我們了解,受環境變遷影響的生物多樣性是否影響生態系統功能性,以及由功能衍生的生態系價值及貢獻(見CIF2102博士後研究計畫書)。我們也將透過與其他子計畫合作,測量沉積物及底棲動物體內的多環芳香烴,進一步探討人為活動產生的持久性有機物染物是否經沉積物源匯過程進入底棲食物鏈。
Abstract: Submarine canyons are major conduits of terrestrial and shelf organic matters, potentially benefiting the seafloor communities in food-deprived deep sea; however, strong bottom currents driven by internal tides and the frequent turbidity flows triggered by storm surges, river flooding, and earthquakes can also be detrimental. In this proposed study, we will investigate carbon cycling in the Gaoping Submarine Canyon (GPSC), a high-particle-yield canyon connected to a small mountain river (SMR) off the SW Taiwan. By contrasting the benthic food web within and outside the GPSC with distinct benthic communities, we aim to examine the role of sediment benthos on organic carbon (OC) cycling in the submarine canyons associated with SMRs.
In the previous FATES projects, we showed that variation in benthic community structure between the GPSC and the adjacent slope was controlled by bottom-intensified current associated with internal tides. In this proposal, we select two locations from the previous surveys with the most contrasted community structure, the head of GPSC and the upper slope, to investigate the benthic community function related to carbon cycling (i.e. carbon remineralization). To contrast the two benthic carbon food webs, we will first measure the standing stocks of living and non-living components of sedimentary OC. The second step is to couple the input and loss of OC (e.g. rain of POC, sediment community oxygen consumption, OC burial rate and predation) with the stock estimates. These rates and processes will be estimated by in-situ, ship-board and laboratory approaches or from literature data (mostly published by FATES project). The third step will be algebraic solution of the unknown predator-prey interactions and carbon flows in the conceptual food web by linear inverse modeling (LIM) assuming steady state.
Over the past decade, the FATES team has contributed significantly to understand source-to-sink dynamic of sediments and OC transports off the SW Taiwan; however, the role of sediment benthos have not been considered previously. In this proposed study, we will focus our carbon budget estimates on biological processes to better understand the fates of OC in the SMR associated canyon. We will use novel benthic lander technology to conduct in-situ sediment incubation, autonomously sediment and water samples recovery, and direct visual observation of deep-sea organisms to estimate the key processes or stocks in the system. All of which will be compared with the ship-board measurement and traditional biological sampling. Carbon cycling is the most important ecosystem function of the seafloor. A postdoctoral researcher applied through this proposal will generate complimentary biodiversity data from the sediment samples, which will be linked to our measured or modeled carbon flow estimates to understand biodiversity-ecosystem functioning relationship (see form CIF2102 for details). We will also collaborate with FATES sub-project to measure the concentrations of polycyclic aromatic hydrocarbons (PAHs) in the surface sediments and in the tissues of the benthos to trace the fates of the PAHs in the marine benthic food webs.
Keyword(s)
屏峽谷
碳循環
微生物
小型
大型
巨型底棲生物
沉積物群聚耗氧量
深 海著陸器
生物多樣性
生態系統功能
Submarine canyons
Gaoping Submarine Canyon
benthic community
carbon cycling
sediment community oxygen consumption
benthic lander
biodiversity-ecosystem functioning relationship