礁石表生藻席（Epilithic algal matrix, EAM）是珊瑚礁区普遍存在的底质类型，在初级生产、营养供应、沉积物富集及珊瑚礁底质演变等关键过程中均发挥重要的功能。为了解礁石表生藻席的群体特征与分布规律，于2022年1月、4月、7月、10月在三亚典型岸礁区设置了调查断面（1m、3m、6m），通过水肺潜水方法调查了礁石表生藻席的分布范围及对不同基底的选择性，同时采集了不同底质类型（分枝状、团块状、坪状珊瑚礁石）中珊瑚碎片上的藻席样品，分析了藻席的群体特征及其时空差异。结果显示，礁石表生藻席分布具有显著空间差异但无明显的季节差异， 覆盖率在1m和6m水深处较高，平均为66.96%，与活珊瑚覆盖率呈现负相关的关系。礁石表生藻席偏爱孔隙度高的硬质基底表面，在坪状珊瑚礁石上具有最高的覆盖度（~98%），但团块状珊瑚礁石上的藻席具有最高的藻体高度（11.16±0.68 mm）、密度（(118.51±33.64 g·m^-3)）和有机质含量（102.49±32.94 g C·m^-2），可能与团块状珊瑚礁石具有比较高的表面孔隙度有关。藻席的表观特征与生物量均有水深和季节的差异，3米水深处最高，1米最低，在时间上则表现为夏季最高，冬季最低，说明温度和光照是影响藻席特征变动的关键因子。研究结果表明，三亚鹿回头近岸珊瑚礁生态系统中，礁石表生藻席均为>5mm的多沉积物型藻席（long sediment-laden algal turfs, LSATs），这种类型的藻席不利于珊瑚幼体附着和植食性鱼类摄食。藻席表观特征与有机质含量有明显的底质和时空差异，藻席中丰富的有机质可为众多底栖小型无脊椎动物提供食物，可能在珊瑚礁生态系统的食物网中发挥不可或缺的重要功能。

The epilithic algal matrix (EAM) is widely distributed in coral reef ecosystems and plays a crucial role in key processes such as primary production, nutrient recycling, sediment deposition, and coral reef phase shift. In order to investigate the morphological characteristics and distribution patterns of EAM, a survey was conducted in the typical fringing reef of Sanya in January, April, July, and October 2022. The survey consisted of three sections (1m, 3m, 6m). The substrate types and their coverage were recorded by video, and three substrate types (branched, massive, planiform) with epiphytic algae were sampled by scuba diving. The results showed significant spatial differences but no seasonal differences in the coverage of EAM in the study area. The coverage rate was higher at depths of 1 and 6 meters, but lower at a depth of 3 meters, with averages of 66.96% and 16.55%, respectively. The coverage of EAM showed a negative correlation with the live coral coverage rate. The EAM is mainly distributed on hard substrate surfaces with high porosity and has the highest coverage degree.98 % of the dead planiform coral reefs appeared. However, the EAM on the dead massive coral reefs exhibited the highest algal height (11.16 ± 0.68mm), biomass (118.51 ± 33.64g∙m^-2), and organic matter content (102.49 ± 32.94g C∙m^-2). This could be attributed to the relatively high surface porosity of the dead massive coral reefs. The morphological characteristics and biomass of EAM vary with depth and season. The highest value is observed at a depth of 3 meters, while the lowest value is found at a depth of 1 meter. In terms of time, the height, density, and biomass of EAM were highest during the summer and lowest during the winter. The results here show that the benthic community in the studying area of Luhuitou, Sanya consists mainly of long sediment-laden algal turfs (LSATs) with high sediment content and a height greater than 5mm. This type of benthic community is not conducive to the settlement of coral larvae and is not consumed by herbivorous fish. The morphological characteristics and organic matter content of EAM exhibit obvious differences in substrate, depth, and seasons. Furthermore, the rich organic matter in the EAM can provide potential food resources for numerous benthic small invertebrates, which play an essential and significant role in the food web of the coral reef ecosystem.