In recent years, anthropogenic impacts are causing a dramatic decline of marine ecosystems, especially in seagrass ecosystems located exclusively in subtidal zone. A full understanding of seagrass dispersal mechanisms and connectivity is very important for successful restoration, conservation, and management of seagrasses.

Halophila ovalis, a seagrass considered a pioneer species that is widely distributed in the Indo-Pacific region, was collected from 4 sites (one in the lagoon and three from open water area) situated in the waters of Dongsha Island to reveal its fine scale connectivity with newly developed microsatellite loci. The results of F-statistics, principal coordinates analysis, and assignment test showed a concordant result that the population inhabiting the semiclosed lagoon is genetically isolated from other populations inhabiting the coastal area of the island. This fine scale genetic structure may shape by physical barriers (restricted water exchange) and the low dispersal capacity of H. ovalis. In conclusion, the lagoon of Dongsha Island could be an isolated habitat in which taxa have experienced unique evolutionary histories; future studies investigating the potential genetic novelty of additional taxa in that area are needed in order to validate the conservation significance of the lagoon of Dongsha Island.

近年来，人为影响导致海洋生态系统急剧下降，尤其是仅位于潮下带的海草生态系统。全面了解海草扩散机制和连通性对于成功恢复、保护和管理海草非常重要。

从位于东沙岛水域的 4 个地点（一个位于泻湖，三个来自开阔水域）收集被认为是广泛分布于印度洋-太平洋地区的先驱物种的海草Halophila 椭圆藻，以揭示其精细尺度的连通性具有新开发的微卫星位点。F统计、主坐标分析和分配检验的结果表明，居住在半封闭泻湖中的种群与居住在岛屿沿海地区的其他种群在遗传上是隔离的。这种精细尺度的遗传结构可能是由物理障碍（限制水交换）和卵圆形H.的低扩散能力形成的. 总之，东沙岛泻湖可能是一个孤立的栖息地，其中的分类群经历了独特的进化历史；未来的研究需要调查该地区其他类群的潜在遗传新颖性，以验证东沙岛泻湖的保护意义。