Silicon is a major driver of global primary productivity and CO₂ sequestration, and is a beneficial element for the growth and environmental stress mitigation of many terrestrial and aquatic plants. However, only a few studies have examined the occurrence of silicon in seagrasses, and its function within seagrass ecosystems and the role of seagrasses in silicon cycling remain largely unexplored. This study uses for the first time two methods, the wet-alkaline digestion and the hydrofluoric acid digestion, to quantify silicon content in seagrass leaves using the species Zostera marina and elaborates on the potential role of silicon in seagrass biogeochemistry and ecology, as well as the role of seagrass ecosystems as a silicon reservoir. The results revealed that seagrass leaves contained 0.26% silicon:dry-weight, which is accumulated in two forms of silica: a labile form digested with the alkaline method and a resistant form digested only with acid digestion. These findings support chemical digestions for silicon quantification in seagrass leaves and provide new insights into the impact of seagrasses on the marine silicon cycle. Labile silica will be recycled upon leaf degradation, benefiting siliceous organisms, while refractory silica will contribute to the ecosystem’s buried silica stock and coupled carbon sequestration. In the Bay of Brest (France), the seagrass silicon reservoir was estimated at 0.18 ± 0.07 g Si m⁻², similar to that of benthic diatoms, underscoring the potential role of seagrasses in silicon biogeochemistry in the land–ocean continuum, where they might act as a buffer for silicon transport to the ocean.

硅是全球初级生产力和 CO₂ 封存的主要驱动力，是许多陆生和水生植物生长和缓解环境压力的有益元素。然而，只有少数研究检查了硅在海草中的存在，其在海草生态系统中的功能以及海草在硅循环中的作用在很大程度上仍未得到探索。本研究首次使用湿碱消解和氢氟酸消解两种方法，使用 Zostera marina 物种量化海草叶中的硅含量，并详细阐述了硅在海草生物地球化学和生态学中的潜在作用，以及海草生态系统作为硅库的作用。结果显示，海草叶含有 0.26% 的硅：干重，它以两种形式的二氧化硅形式积累：一种是用碱性方法消化的不稳定形式，另一种是仅用酸消化消化的抗性形式。这些发现支持海草叶中硅定量的化学消化，并为海草对海洋硅循环的影响提供了新的见解。不稳定的二氧化硅将在叶片降解时回收利用，使硅质生物受益，而难降解二氧化硅将有助于生态系统的埋藏二氧化硅存量和耦合碳封存。在布雷斯特湾（法国），海草硅储层估计为 0.18 ± 0.07 g Si m⁻²，与底栖硅藻相似，强调了海草在陆地-海洋连续体中硅生物地球化学中的潜在作用，在那里它们可能充当硅向海洋运输的缓冲器。