東沙島周圍海草分布特徵
Other Title
Distributional Characteristics of the Seagrasses Encircling the Dongsha Island
Journal
航測及遙測學刊
Journal Volume
16
Journal Issue
3
Start Page
167
End Page
180
ISSN
1021-8661
Date Issued
2012-08
Author(s)
Abstract
海草為淺海域水質與污染的敏感指標，透過萃取則可用於多類產品的開發，具有高度的生態與經濟價值。東沙島為茂密的海草床所環抱，出現的海草至少有六種，占全世界海草種數的10%，是為亞洲地區海草的分布重鎮。本研究結合東沙島周圍海草床的地面調查與測深光達資料（LiDAR），探討東沙島周圍海域海草的分布特性，並以橢球高（altitude）作為調查點平均水深的基礎，分析各項海草因子與水深之間的關係。調查結果顯示，水深範圍從0到6.8公尺處皆有海草分布，混生情形從單種到四、五種海草共存，在水深1到3公尺可觀察到最多種類的海草共存，水深1公尺內則多為單種或兩種海草混生；而在水深小於3公尺的樣點中，有超過93%出現海草，覆蓋度以50%到80%的頻度最高；從各種海草的分布來看，圓葉水絲草與泰來草的分布深度顯著小於水韭菜與鋸齒葉水絲草。整體而言，東沙島周圍海草大致呈現固定的種類分布，水深則是影響不同種類海草分布與共存之重要因子，並影響海草在東沙島周圍的地理分布。此外，由測深光達資料衍生之環境因子（如水深）有助於生物分布與生態監測研究。
Seagrasses are as important indicator of water quality and pollution in the shallow-ocean zone and extracts from seagrasses can be used widely, leading them to a high value on both ecology and economy. Dongsha Island, surrounded by abundant seagrass meadow and composed of at least six species accounted for 10% of the world, is a main habitat for seagrasses in Asia. We combined field data of the seagrasses with environmental factors derived from LiDAR around the Dongsha Island to understand distributional characteristics of the seagrasses and to compare effects of water depth on seagrasses' distributions. Our results indicated that, seagrasses were found in the depth of 0 to 6.8m, with the coexistence of 1 to 5 species. The highest number of seagrass species was coexisted in the depth of 1 to 3m while single or two seagrass species were often observed within depth of 1m. In the depth within 3m, the seagrass bed had the highest occurrence frequency, up to 93%, where the most sites had the leaf cover within 50% to 80%. We also found that the seagrasses Cymodocea rotundata and Thalassia hemprichii occupied the depths less than Cymodocea serrulata and Syringodium isoetifolium. Overall, the seagrasses encircled the Dongsha Island show specific preference, and their distributional characteristics and coexistence are affected most by water depth. The environmental data derived from LiDAR can be further useful on species distributions and ecological monitoring.
Subjects
分布
distribution
東沙島
海草
測深光達
Dongsha Island
LiDAR
seagrass
Publisher
中華民國航空測量及遙感探測學會
Type
journal article