利用對底棲生物群聚及其特徵的了解來優化珊瑚復育方法

珊瑚礁是重要的海洋生態系之一，然而近年來全球氣候變遷和各種有害的人為活動造成了珊瑚礁的衰退。為了減緩衰退，不同的珊瑚復育方法因而被提出來，例如使用遠端遙測技術來偵測衰退的珊瑚礁、珊瑚種苗放流、選擇較具抵抗性的珊瑚群體進行繁殖以及藉由優先選取特定表徵的物種來刺激基因流動以幫助珊瑚演化的目的。然而，上述這些方法大多所費不貲且無法顯著地在大空間尺度上保育這個生態系。本研究提出了一個可以應用在一定空間規模的復育方法，藉由鑑定出不同的底棲群聚，再挑選這些群聚內關鍵的石珊瑚型態功能群(morpho-functional groups)並優先種植以促進群聚的動態消長。我們在菲律賓馬比尼阿尼洛的五個區域內橫跨三個深度(5、10、15米) 共記錄了55條穿越線，並且記錄在每條側線上拍攝的21張照片中出現的型態功能群來計算底棲生物的組成。我們使用 k-平均演算法(k-means)來找尋最佳的分群數量以代表底棲群聚數量,並計算每個群聚的hill指數以作為此群聚的多樣性特徵。我們在每個群聚的共現網絡(Co-occurrence) 分析中取最高介數中心性的底棲生物型態功能群做為此群聚內的關鍵型態功能群。k-平均演算法表示七個群聚為最佳的分群數量，且各群聚皆擁有不同的特性和多樣性。然而因為群聚4缺乏重複的穿越線，只有六個共現網絡能被分析，。在這六個網絡中，關鍵的底棲生物生長型態為葉片狀的石珊瑚(群聚1、2、5)、皮質較厚的藻類(群聚3)、表覆型海綿(群聚5)、枝狀石珊瑚(群聚6)和桌狀石珊瑚(群聚7)。有趣的是，每個群聚的關鍵底棲型態功能群皆不相同。在這些群聚中，我們以關鍵的石珊瑚生長型態為移植的目標，並從中挑選出不受人為壓力影響的群體來當作移植的母群體，以作為當地在未來可以實施的珊瑚復育指南。這些從關鍵的石珊瑚生長型態上採取的分枝很有可能會加快當地生態動態的消長。本研究旨在發展一個不昂貴的珊瑚移植方法來連結科學和當地的保育工作以造就更好的珊瑚移植策略。

關鍵字

珊瑚礁；底棲群落；共現網絡；介數中心性

並列摘要

The coral reefs are important marine ecosystems but they face degradation due to anthropogenic climate change and other harmful human activities. To slow down this decline, various coral restoration approaches exist such as remote sensing technology in detecting degraded coral reefs, reseeding reefs with cultivated larvae, assisting their evolution such as selecting and breeding resistant genets, and/or stimulating gene flow by prioritizing coral species with desirable phenotypic traits. However, these procedures are often expensive and difficult to apply at a spatial scale that could be significant for conserving these ecosystems. Here, we propose a scalable restoration method based on a prior identification of the benthic communities (BC) and the selection of scleractinian key morpho-functional groups that should be outplanted to encourage dynamic succession. A total of 55 transects among 5 geographical areas in Anilao, Mabini, Philippines at three depths (5m, 10m, 15m) were selected for survey in this study. For each transect, the benthic composition in morpho-functional categories was documented after examining 21 photographs of the organisms present. The optimum k number of clusters, reflecting the number of BCs, was identified by using k-means clustering (unsupervised learning algorithm). The characterization of the diversity was measured by calculating the hill numbers in each of the delineated BCs. In each BC, co-occurrence network analysis was built to identify the key morpho-functional group with the highest betweenness centrality. The results identified seven BCs with varying characteristics and diversities. However, only six co-occurrence networks were built due to lack of replicate in the 4th BC. Within the six networks, the key morpho-functional groups are foliose hard corals (BC 1, 2, 5), corticated foliose algae (BC3), encrusting sponge (BC5), arborescent hard corals (BC6), and tabular hard corals (BC7). Interestingly, the results of the key morpho-functional groups varied in each community. Among these benthic communities, scleractinian key morpho-functional groups will be targeted and resilient colonies presenting no obvious sign of stress will be selected as donor colonies to implement a coral restoration protocol with local communities in the future. Potentially, coral nubbins of the key morpho-functional groups will impulse ecological dynamic succession. This project aims to advance towards a coral restoration strategy by developing an inexpensive methodology to bridge science and conservation efforts by local communities.

並列關鍵字

coral reefs ； benthic communities ； co-occurrence network ； betweenness centrality

參考文獻

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利用對底棲生物群聚及其特徵的了解來優化珊瑚復育方法

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