桃園觀塘地區柴山多杯孔珊瑚之分布

Abstract

柴山多杯孔珊瑚是台灣的一級保育類珊瑚，目前已知的最大族群位於桃園的大潭藻礁。其存在突顯了大潭藻礁的生物多樣性，卻因為第三天然氣接受站在當地的開發案而受到威脅，使其成為各界關注的爭議焦點。然而此珊瑚在野外的紀錄相當稀少觀，在缺乏資料的情況下難以進行客觀評估，導致爭議大幅延宕。 本研究利用臺灣中油公司在該地所進的監測資料進行分析，使用地理資訊系統將珊瑚點位和環境數據進行疊合，以了解此物種的棲地偏好和潛在分布範圍。結果顯示： 1. 在Mann-Whitney U-test statistic的檢定中，將珊瑚點位和隨機點位的環境因子進行比較，發現水深、離岸距離和低潮線距離等三項環境因子幾乎在每一季的調查中都呈現顯著差異，而懸浮固體濃度和濁度在半數以上的調查中皆未呈現顯著差異。2. 在Wald-Wolfowitz runs test檢定中，族群特徵的部分在群落數量和平均面積皆無特定趨勢，環境因子的部分僅有懸浮固體濃度呈現非隨機的變化，在濁度、深度、離岸距離和低潮線距離等項目皆無特定趨勢。3.在分布熱點的部分，過去16季的調查皆集中出現於少數特定區塊，並未隨著季節或年度而出現明顯變化。4. 在潛在分布範圍的部分，以深度、離岸距離、低潮線距離等三項環境因子的數值範圍進行疊合，呈現出狹長的區塊，沿著岸邊呈現水平分布並緊貼低潮線的兩側。 綜合以上結果推論，柴山多杯孔珊瑚的主要限制因子可能是光照條件而非絕對深度，其分布範圍可能超乎以往的認知，未來的調查應採取水下作業的方式進行，擴大調查範圍以發現未知的潛在族群；同時也應針對潮間帶的潮池進行重點保育，維護潛在的棲地範圍以確保此物種的存續。

Polycyathus chaishanensis has been classified as an "endangered species" in Taiwan, with its largest known population located at the Datan algal reef in Taoyuan. Its presence underscores the crucial importance of biodiversity in Datan algal reef. However, this population was threatened by the construction of third liquefied natural gas (LNG) receiving terminal, which has sparked considerable controversy. Unfortunately, the records of this coral in the wild are quite sparse. The lack of data complicates the assessment, thus remaining a contentious issue. In this study, data sourced from the Chinese Petroleum Corporation, Taiwan, were analyzed to understand the habitat preferences and potential distribution of Polycyathus chaishanensis. We utilize geographical information system (GIS) to correlate coral locations with environmental data. The results indicate: 1. In the Mann-Whitney U-test, comparisons between environmental factors at coral points and random points revealed that water depth, offshore distance, and low tide line distance consistently showed significant differences across nearly every survey season, whereas suspended solids concentration and turbidity did not exhibit significant differences in more than half of the surveys. 2. The Wald-Wolfowitz runs test indicated no specific trends in the number and average area of colony. Among environmental factors, only suspended solids concentration exhibited non-random changes, while turbidity, depth, offshore distance, and low tide line distance showed no specific trends. 3. The distribution of hotspots over the past 16 seasons concentrated in a few specific areas, with no apparent seasonal or annual changes. 4. The potential distribution range was depends on the overlapping of the numerical ranges of depth, offshore distance, and low tide line distance, which perform a narrow block and horizontally distributed along the shore. Based on these results, it can be inferred that the primary limiting factor for Polycyathus chaishanensis may be the light availability rather than absolute depth, and its distribution range may exceed previous knowledge. Future research should include underwater surveys to broaden the investigative area and discover previously undetected populations. Additionally, conservation efforts should focus on tide pools in the intertidal zone to maintain the potential habitat range and ensure the survival of this species.