在海底溫泉的極端環境中存活的生命

原文網址：https://www.uni-kiel.de/en/details/news/363-hot-springs

在海底溫泉的極端環境中存活的生命

基爾大學的海洋學者破解了生活在台灣活火山的生物群體如何適應環境的機制

台灣的火山島―龜山島的淺海地區空照圖，可以透過被硫染成白色的海水來看出酸性溫泉的位置。圖片來源：Mario Lebrato, Uni Kiel

對於海洋生物來說，台灣東北方的火山島――龜山島是環境十分極端的棲地。由於龜山島是座活火山，因此近海地區成為獨特的熱液場域，具有許多溫泉並冒出火山氣體，使得研究區域的海水酸度是世上首屈一指，而這裡也出現了某些相當特化的海洋生物，像是螃蟹。因為龜山島附近的淺海區域相當容易到達，所以是理想環境來研究海洋生物如何適應酸度和毒性都很高的海水。

基爾大學地球科學研究所的海洋學者，聯合中國杭州浙江大學和台灣基隆國立台灣海洋大學的研究人員，用了十年左右定期採集此處的地質、化學和生物作用的樣品。途中在2016年發生了兩次擾動事件而對這段時間的結果有所干擾。首先是龜山島受到了一場地震的劇烈晃動，接著在短短數個禮拜之後，又遭遇了強烈颱風尼伯特的襲擊。基爾大學、中國和台灣的研究人員根據他們多年來蒐集到的資料，首次呈現出大地震與強烈颱風帶來的後果，會讓生地化作用出現什麼樣的變化；此外，他們也描述了不同生物如何在短短的一年之內就適應了海水的生物地球化學變化。這項跨領域研究援用的大量資料最早可追溯到1960年代。他們的第一批成果最近發表在自然集團之下的國際期刊《科學報告》(Scientific Reports)。

基爾大學地球科學研究所的Mario Lebrato博士表示：「我們的研究清楚顯示了大氣、地質、生物和化學作用的交互關係有多麼密切，同時也顯示出有火山為熱源的海底，這類生存環境相當極端的生態系，如何因應自然事件帶來的擾動。」基爾大學地球科學研究所的Dieter Garbe-Schönberg 博士和Mario Lebrato博士領導的研究團隊，多年來持續研究龜山島的淺海熱液系統。他們選定的研究地點有大量的二氧化碳從淺海冒出，同時也釋放出有毒的金屬。大範圍的海水因為硫而被染成不同顏色，帶有高濃度硫化物的火山氣體也讓海水的酸度大幅提高。透過空中無人機調查、電腦模擬、定期採樣和實驗室試驗來研究這處熱液場域，可以提供相當重要的資訊來讓我們了解海洋酸化對海洋生物的影響。在最靠近熱源的區域只有幾種特化過的生物可以生存，像是螃蟹、螺類和細菌，但到了幾公尺之外，就像是熱帶海洋般擁有各式各樣的生物。

台灣的火山島―龜山島附近的淺海地區冒出氣體的水下照片。這些富含二氧化碳和硫化物的氣體使得海水酸化。圖片來源：Mario Lebrato, Uni Kiel

共同作者Yiming Wang最近剛從基爾大學轉往耶拿的馬克斯普朗克人類歷史科學研究所。她說：「由於此處常見的生活環境中海水具備高酸性、大量有毒物質和高溫的特性，因此可以視為一處天然實驗室來探討人類造成嚴重環境汙染後會帶來的影響。故在研究未來可能面臨的狀況時，龜山島的熱源便是理想對象之一。」

2016年的重大事件發生之後，研究區域完全變了個樣。海床被一層厚厚的沉積物和礫石覆蓋住，酸性海水的來源也跟著枯竭，使得此處的海水性質發生了重大且持續許久的變化。無人機拍下的空照圖、基爾大學與台灣研究人員潛入水下採集的樣品以及對生地化特性的研究，都清楚顯示了事件的擾動範圍之大並造成了劇烈的化學變化。生物學家暨潛水研究員Mario Lebrato夥同台灣的曾立鈞將這些變化紀錄下來之後，和更早以前的樣品進行比對。研究主持人，基爾大學地質研究所的Dieter Garbe-Schönberg博士解釋：「對當時我們正在連續進行的研究來說，最初看起來就像是場重大災難的事件，卻在之後變成意料之外的好運。透過搜集各個層面的資料，這給了我們相當難得的機會來觀察生物如何適應突然出現的嚴重擾動。」

這是研究計畫「以龜山島熱液場域為天然實驗室來探討海洋酸化的影響」(2020年12月20日結案)的第一批成果。經費來自德國聯邦科技教育部，歸屬於永續發展研究的計畫架構之下，並和台灣與中國的研究人員密切合作下執行。

Life under extreme conditions at hot springs in the ocean

Marine researchers at Kiel University decipher adaptation mechanisms of biological communities to an active volcano in Taiwan.

The volcanic island of Kueishantao in northeastern Taiwan is an extreme habitat for marine organisms. With an active volcano, the coastal area has a unique hydrothermal field with a multitude of hot springs and volcanic gases. The acidity of the study area was among the highest in the world. The easily accessible shallow water around the volcanic island therefore represents an ideal research environment for investigating the adaptability of marine organisms, some of which are highly specialised, such as crabs, to highly acidified and toxic seawater.

For about ten years, marine researchers from the Institute of Geosciences at Kiel University (CAU), together with their Chinese and Taiwanese partners from Zhejiang University in Hangzhou and the National Taiwan Ocean University in Keelung, regularly collected data on geological, chemical and biological processes when two events disrupted the results of the time series in 2016. First, the island was shaken by an earthquake and hit by the severe tropical typhoon Nepartak only a few weeks later. On the basis of data collected over many years, the researchers from Kiel, China and Taiwan were now able to demonstrate for the first time that biogeochemical processes had changed due to the consequences of the enormous earthquake and typhoon and how different organisms were able to adapt to the changed seawater biogeochemistry in the course of only one year. The first results of the interdisciplinary study, based on extensive data dating back to the 1960s, were recently published in the international journal Nature Scientific Reports.

"Our study clearly shows how closely atmospheric, geological, biological and chemical processes interact and how an ecosystem with extreme living conditions such as volcanic sources on the ocean floor reacts to disturbances caused by natural events," says Dr. Mario Lebrato of the Institute of Geosciences at Kiel University. For years, scientists led by Dr. Dieter Garbe-Schönberg and Dr. Mario Lebrato from the Institute of Geosciences at the CAU have been researching the shallow hydrothermal system "Kueishantao". The selected site has a large number of carbon dioxide emissions in the shallow water. In addition, the sources release toxic metals. Sulphur discolours the water over large areas. The volcanic gases - with a high sulphur compounds - lead to a strong acidification of the sea water. Through methods of airborne drone surveying, modelling, regular sampling and laboratory experiments research into the hydrothermal field therefore makes an important contribution to the effects of ocean acidification on marine communities. Only a few specialized animal species such as crabs, snails and bacteria live in the immediate vicinity of the sources. A few metres away, on the other hand, is the diverse life of a tropical ocean.

"Due to the high acidity, the high content of toxic substances and elevated temperatures of the water, the living conditions prevailing there can serve as a natural laboratory for the investigation of significant environmental pollution by humans. The sources at Kueishantao are therefore ideal for investigating future scenarios," says co-author Dr. Yiming Wang, who recently moved from Kiel University to the Max Planck Institute for the Science of Human History in Jena.

After the severe events in 2016, the study area changed completely. The seabed was buried under a layer of sediment and rubble. In addition, the acidic warm water sources dried up, and the composition of the sea water had significantly and continuously changed over a long period of time. Aerial photos taken with drones, samples taken by research divers from Kiel and Taiwan as well as biogeochemical investigations clearly showed the spatial and chemical extent of the disturbances. These were recorded by the biologist and research diver Mario Lebrato and his Taiwanese colleague Li Chun Tseng and compared with the results of earlier samplings. "What initially looked like a catastrophe for our current time series study turned out to be a stroke of luck afterwards. This gave us the rare opportunity to observe how organisms adapt to the severe disturbances. We were able to draw on a comprehensive database to do this" explains project manager Dr. Dieter Garbe-Schönberg from the Institute of Geosciences at Kiel University.

The study is the first result of the project "The Kueishantao hydrothermal field as a natural laboratory for the investigation of the effects of ocean acidification" (until December 2020), funded by the Federal Ministry of Education and Research (BMBF) within the framework of the programme Research for Sustainable Development (FONA3) and have been carried out in close cooperation with Taiwanese and Chinese partners.

原始論文：Mario Lebrato, Yiming V. Wang, Li-Chun Tseng, Eric P. Achterberg, Xue-Gang Chen, Juan-Carlos Molinero, Karen Bremer, Ulrike Westernströer, Emanuel Söding, Hans-Uwe Dahms, Marie Küter, Verena Heinath, Janika Jöhnck, Kostas I. Konstantinou, Yiing J. Yang, Jiang-Shiou Hwang, Dieter Garbe-Schönberg. Earthquake and typhoon trigger unprecedented transient shifts in shallow hydrothermal vents biogeochemistry. Scientific Reports, 2019; 9 (1) DOI: 10.1038/s41598-019-53314-y

引用自：Kiel University. "Life under extreme conditions at hot springs in the ocean."