2015-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/705128摘要：生物多樣性的喪失是生態系永續發展所面臨的迫切問題。各種理論和實驗已證明了生物多樣性對生態系功能呈一正相關係，然而在自然狀態下的觀測研究結果卻未必和操控實驗的結果一致(其結果可能為正向的,負向的,單峰的,或是沒有關係)。而這個不一致性可能源於過度簡化的操控實驗設計與許多不實際的假設，使得其無法在自然狀態下得到印證。這些不實際的假設包含: (1)多數現有實驗只考慮單一營養階層；(2)實驗設計的環境維持穩定；(3)實驗可操控的生物多樣性梯度相對較小。 為了彌平理論與實證的落差，本研究對台灣周邊海洋生態系進行調查，以期探討在環境變化下營養階層間生物多樣性的關係及其對生態系功能的影響。在此，生態系功能著重於生產力和能量傳遞效率，因為這些功能與人類所仰賴的生態系服務密切相關。營養階層則著重於掠食者與獵物，並探討其生物多樣性之間的關係以及其對生態性功能的影響。我們提出以下幾個假說逐一進行檢驗：(H1)依據生態棲位分化理論，掠食者多樣性會隨獵物的多樣性升高而增加；(H2)掠食者多樣性的增加會促使能量傳遞效率的提升，但獵物多樣性的增加卻會降低能量傳遞效率。這是因為掠食者的攝食率會隨自身多樣性增加而提升，但隨獵物多樣性增加而下降。抑或是因為獵物的防禦會因自身多樣性增加而增強，但隨掠食者多樣性增加而降低；最後並比較與檢驗生物多樣性和生態系功能關係的經典假說，即(H3)單一營養階層的生產力會隨其多樣性增加而提升，但此一假說並不考慮掠食者與獵物間的交互作用。 本研究主要先探討兩種捕食者與獵物的關係(即浮游動物-浮游植物、原生生物-細菌)。透過傳統顯微鏡計數、影像分析與次世代定序量化群聚結構以估算其生物多樣性，而估算方法包含物種分類多樣性、系統演化多樣性與功能特徵多樣性。由於判斷功能特徵的困難，我們以體型大小為代表，其為生物最重要的功能特徵。而生態系功能則以即時測量(on-board incubation experiments)之生產力與營養階層間的能量傳遞效率為代表，這兩個功能皆在食物網完整性上扮演重要角色。而該處的環境效應(如溫度、鹽度、營養鹽等)也會納入考量。為了避免不符合實際狀況的實驗設定，我們對一個涵蓋明顯環境梯度和生物多樣性梯度的海域進行採樣和量測，而非人為的操控物種與環境梯度。 本研究的主要目標為實證多個營養階層之生物多樣性對其生態系功能的影響，此一結果將有助於海洋生態系管理以及漁業管理的應用。本研究計畫屬跨領域計劃的一部分，該計畫為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。 <br> Abstract: Biodiversity lost is a pressing concern for ecosystem sustainability, because various theoretical studies and experiments have demonstrated a positive relationship between biodiversity and ecosystem functioning (known as BEF). However, observational studies in natural systems revealed complicated patterns (positive, negative, uni-modal and no clear BEF); these findings are inconsistent with manipulative experimental results. The inconsistency may arise because several unrealistic assumptions have been made in overly simplified experimental design that cannot be justified in natural systems: 1) most of existing experiments consider only single trophic level, 2) environmental conditions are hold constant in experiment, and 3) relative small gradient of diversity was considered. To fill the knowledge gap, we propose to study multi-trophic level diversity relationships and the consequences on ecosystem functioning in the context of environmental changes in the marine ecosystems surrounding Taiwan. Here, for ecosystem functioning, we focus on production and trophic transfer efficiency, because these functionings are closely related to ecosystem services that human beings necessarily rely upon! Specifically, we focus on predator-prey pairs, and we investigate their diversity relationship as well as the effects of multi-trophic level diversities on ecosystem functioning. We have the following hypotheses to guide our research. H1: Predator diversity increases with prey diversity, according to the niche diversification theory. H2: Trophic transfer efficiency increases with predator diversity but decreases with prey diversity. This is because predator consumption increases with predator diversity but decreases with prey diversity, and/or, prey defense increases with prey diversity but decreases with predator diversity. As a comparison, we also test the classic hypothesis, H3: Production increases with diversity within a trophic level. The caveat of this hypothesis is that predator-prey interaction is not considered. To begin to tackle this complex issue, we focus on two predator-prey pairs: zooplankton VS phytoplankton and protists VS bacteria. Biodiversity quantification includes taxonomic diversity, phylogenetic diversity, and trait diversity where data are available, through traditional microscopic counting, image analysis, and molecular methods based on Next Generation Sequencing. Due to the difficulty in gathering traits data in field, here we focus only on size, as bodysize has been considered as the master trait of organisms. For ecosystem functioning, we focus on production and trophic transfer efficiency across adjacent trophic levels; those processes are critical for foodweb integrity and will be measured using on-board incubation experiments. As those variables will be measured in situ, the environmental effects (e.g. temperature, salinity, nutrients, and etc.) will have to be accounted for statistically. Note that we choose to carry out sampling and measurements across a large gradient of environmental conditions as well as diversity to study the BEF, instead of artificially manipulating the gradient by introducing species or changing environmental condition, to avoid unrealistic setting. The main objective here is to integrate and test empirically the effects of multi-trophic level biodiversity on ecosystem functioning. Our results have strong implications to marine ecosystem management as well as fisheries. Our project is part of the interdisciplinary project: Effects of Global Change on Ocean Biogeochemistry and Ecosystems in the Seas surrounding Taiwan in the Northwest Pacific (ECOBEST).生物多樣性跨營養階層功能特徵取向的方法攝食關係氣候變遷生態系功能生態系完整性Biodiversitymultiple trophic levelstrait-based approachtrophic interactionsclimate changeecosystem functioningecosystem integrity