Abstract
摘要:台灣西南海底峽谷是海洋沉積物從源到匯的活教材。它們是陸源及海源有機碳進入深海的主要通道,滋養食物匱乏的深海生態系。但峽谷裡的海底山崩,洪水引發的異重流,地震或颱風造成的重力流都可能引發海底地質災害,摧毀生物的棲地。一般而言,沉積物中底棲無脊椎生物具有沉積物改造,碳循環和營養鹽再生等生態系功能,影響海洋生地化循環。另一方面,底棲生物也忠實反應環境擾動及變遷。雖然西南海域的地質研究已產生了豐富的文獻,我們仍然不了解海底峽谷對底棲生物的影響,及這些生物在沉積物生態系扮演的角色。因此我們將對台灣西南海域(水深200〜3200公尺)底棲無脊椎生物群聚結構及生態系統功能進行定量研究。1) 我們將調查海底峽谷(高屏峽谷)和非峽谷(高屏斜坡)之間的生產力和環境擾動梯度,將如何影響底棲多樣性及組成。2) 受環境梯度影響的多樣性變化,將如何影響生態系功能以及由功能衍生的生態系服務。氣候變遷及人類活動將可能改變風暴和洪水的頻率和強度,及其引發的海底地質災害,本研究將有助於了解人類活動對深海生物群聚結構及生態系功能的可能影響。並透過連結生物多樣性與生態系功能,來評估喪失海洋生物多樣性對海洋生態系統及人類社會造成的影響。
Abstract: Submarine canyons off SW Taiwan have been an instructional source-to-sink pathway of sediment transports. They are not only the conduits for terrestrial and marine organic carbon to the deep sea, potentially nourishing the food-depriving life on the seafloor, but also a devastated force that can exterminate the benthic communities through strong tidal-driven internal waves, sediment slumping, turbidity and debris flows. Despites a wealth of rich literatures and intense geological studies in the region, no information is available to comprehend the fate and ecological role of the sediment-dwelling infauna invertebrates, which may have important ecosystem functions such as sediment reworking, carbon cycling and nutrient regenerations in the ocean.
Due to rich in food supplies, submarirne canyons are often recognized as hotspots of biomass, productivity biodiversity, and important fishing grounds; however, these observations are mostly based on researches on passive margins surrounding the developed countries. Little information is available to understand the ecological processes of submarine canyon in the active margin setting, which often subjected to high-particle-yield small mountain rivers and frequent submarine geohazards.
In this study, we will conduct a quantitative investigation of deep-sea (200 to 3000-m depth) sedimentary communities and ecosystem functioning on the continental margin off SW Taiwan. 1) We will examine how the unique productivity and disturbance gradients between the submarine canyons (Gaoping Submarine Canyons) and non-canyon slope (Gaoping Slope) may influence the diversity and composition of deep-sea benthos, and 2) how the changes in biodiversity may affect the ecosystem functioning, as well as the goods and service it may generate. The main sampling tool will be mega-multicorer for benthic meiofauna and macrofauna. The recovered sediment cores will be subjected to ship-board incubations at in-situ temperature to measure sediment total oxygen utilization (TOU) and nutrients regeneration. Sediment porewater microprofile will also be conducted to measure oxygen penetration depth and the diffusive oxygen untilization (DOU). The benthos oxygen utilization (BOU) will then be inferred from the difference between TOU and DOU to examine the effects of fauna bioturbation and bioirrigation on sediment oxygen dynamics. All of these activities are aimed to quantify and understand the community structure and function in the submarine canyon vs. slope setting off SW Taiwan.
Given that climate changes and anthropogenic impacts may alter the frequencies and intensities of the storm and flood induced submarine geohazards, this study will demonstrate how the human activities on land can possibly affect the life and functions on the seafloor thousands of meters below the ocean surface. It is also urgent to bridge the gap between deep-sea diversity and ecosystem functioning, so the consequence of the loss of marine biodiversity through human activities can be evaluated.
Keyword(s)
台灣西南海底峽谷
底棲無脊椎生物
沉積物生態系
生物多樣性
生態系統功能性
Submarine canyons off SW Taiwa
sediment-dwelling infauna
abundance
biomass
diversity
ecosystem functioning