The seagrass Cymodocea nodosa and the chlorophyte Ulva rigida growing in the upper sublittoral zones of the Mediterranean Sea are exposed to air during low tides. We compared the desiccation coefficient (k), and the photosynthetic performance (ΔF/Fm’) of C. nodosa leaves with and without epiphytes to that of U. rigida. The recovery ability of these two species was assessed by ΔF/Fm’, after re-immersion. The desiccation coefficient (k) significantly (p < 0.01) varied among the three macrophyte materials, while the lowest k values were measured both in C. nodosa leaves with epiphytes and U. rigida. ΔF/Fm’ significantly declined with decreasing RWC for all materials, while significant differences in the physiological response were observed between U. rigida and the other two materials. Thallus pieces of U. rigida showed higher desiccation tolerance compared to C. nodosa leaves, with its ΔF/Fm’ under 75% degree of dehydration reaching to its initial values thirty (30) minutes after re-immersion, when C. nodosa only reached the 50%. This study provides valuable information on possible changes in the two species distribution under different desiccation scenarios.

地中海海沿岸上亚带生长的海草Cymodocea nodosa和绿藻Ulva hardica在退潮期间暴露于空气中。我们比较了干燥系数（k），和光合性能（ΔF/ FM'）C.性多动脉炎的叶子有和没有附生到的U.杜松。重新浸没后，通过ΔF/ Fm'评估这两种物质的恢复能力。在三种大型植物材料中，干燥系数（k）显着（p <0.01）变化，而在附生植物和硬皮U. nodosa叶片中均测得了最低的k值。对于所有材料，ΔF/ Fm'随RWC的降低而显着下降，而在刚性链霉菌和其他两种材料之间观察到生理反应的显着差异。的菌体件U.杜松相比显示出更高的耐干燥C.性多动脉炎下脱水的75％程度达到其初始值的叶子，其ΔF/ FM” 30后（30）分钟再浸泡，当C.性多动脉炎只达到50％。这项研究提供了有关不同干燥情况下两种物种分布可能变化的有价值的信息。