Seagrasses are among the most important ecosystems of continental and island coastal waters globally. Analyses of the species diversity, structure, and distribution mapping of seagrass communities provide a scientific basis for seagrass conservation and development and protection of the marine environment. The application of remote sensing, especially using very high-resolution remote sensing data, in mapping seagrass distribution confers high accuracy and detailed results. The distribution of seagrass communities and benthic biomes typical of Nam Yet Island, Truong Sa Archipelago, Vietnam was mapped using object-based classification of Pléiades satellite imagery with four spectral bands (red, blue, green, and near-infrared) and the Green–Blue Normalized Difference Vegetation Index, combined with handheld positioning devices (total field samples 100, overall accuracy 91%, kappa coefficient = 0.88). Besides, by sampling and measurement in the field, two seagrass species, Thalassia hemprichii and Halophila ovalis were identified with the same structure, density, and biomass in the northern and southern parts of the island. The application of high-resolution remote sensing images combined with field surveys contributes to improving the accuracy of seagrass distribution maps as well as benthic biome ones for shallow sea areas. Establishing a seagrass distribution map and assessing the diversity of seagrass is the basis for the conservation and development of the current seagrass community at Nam Yet Island.

海草是全球大陆和岛屿沿海水域最重要的生态系统之一。对海草群落的物种多样性、结构和分布图进行分析，为海草的保护和开发以及海洋环境的保护提供科学依据。遥感应用，特别是使用非常高分辨率的遥感数据，在绘制海草分布图时可以获得高精度和详细的结果。使用具有四个光谱带（红色、蓝色、绿色和近红外）和绿色-蓝色归一化差异植被指数，结合手持定位设备（总现场样本100个，整体精度91%，kappa系数=0.88）。此外，通过野外采样和测量，两种海草，Thalassia hemprichii和Halophila ovalis在该岛的北部和南部被确定为具有相同的结构、密度和生物量。高分辨率遥感影像与实地调查相结合的应用有助于提高海草分布图以及浅海地区底栖生物群落分布图的准确性。建立海草分布图和评估海草多样性是南耶岛当前海草群落保护和发展的基础。