Cymodocea nodosa , a typical marine angiosperm species in the Mediterranean Sea, hosts a range of epiphytic algae. Epiphyte abundance varies at different spatial scales, yet epiphyte diversity and community composition are poorly understood. This study explores the epiphytes on C. nodosa from two reference meadows (Thasos, Vrasidas) and one anthropogenically stressed meadow (Nea Karvali) in the northern Aegean Sea (Kavala Gulf, Greece). A nested destructive sampling design at three spatial scales (metres, hundreds of metres, kilometres) and stereoscopic/microscopic observations were used. Light microscopy revealed a total of 19 taxa of macroalgae populating the leaves of C. nodosa . The most commonly encountered taxa with highest cover (%) were Hydrolithon cruciatum and Feldmannia mitchelliae . DNA sequencing (18S rDNA) confirms the presence of a number of dinoflagellate and red algal epiphytes, and this represents the first application of DNA metabarcoding to study the diversity of seagrass epiphytes. Epiphytic communities studied at species/taxon and functional (Ecological Status Groups) levels separated the reference low-stressed meadows from the degraded one, with the functional approach having higher success. The ecological evaluation index classified the studied meadows into different Ecological Status Classes according to anthropogenic stress.

中文翻译：

---

地中海海草Cymodocea nodosa藻类附生植物的多样性和组成：一项基于规模的研究

夜蛾（Cymodocea nodosa）是地中海中典型的海洋被子植物，拥有一系列附生藻类。附生植物的丰度在不同的空间尺度上变化，但是对附生植物的多样性和群落组成知之甚少。这项研究探索了北部爱琴海（希腊卡瓦拉湾）的两个参照草甸（Thasos，Vrasidas）和一个人为胁迫的草甸（Nea Karvali）上结节藻的附生植物。使用了三个空间尺度（米，数百米，公里）的嵌套破坏性采样设计和立体/显微镜观察。光学显微镜显示共有19种大型藻类分布于结球藻的叶子。覆盖率最高（％）的最常见的分类单元是十字绣水Hydro（Hydrolithon cruciatum）和米德耳（Feldmannia mitchelliae）。DNA测序（18S rDNA）证实了许多鞭毛藻和红色藻附生植物的存在，这代表了DNA元条形码技术首次用于研究海草附生植物的多样性。在物种/分类群和功能（生态状态组）水平上研究的附生群落将参考低应力草地与退化草地分离开来，其中功能性方法取得了较高的成功。生态评估指数根据人为压力将研究的草地分为不同的生态状况等级。在物种/分类群和功能（生态状态组）水平上研究的附生群落将参考的低应力草甸与退化的草甸分离开来，其中功能性方法取得了较高的成功。生态评估指数根据人为压力将研究的草地分为不同的生态状况等级。在物种/分类群和功能（生态状态组）水平上研究的附生群落将参考低应力草地与退化草地分离开来，其中功能性方法取得了较高的成功。生态评估指数根据人为压力将研究的草地分为不同的生态状况等级。