Fisheries Research Institute (HAO-DEMETER), 640 07, Nea Peramos, Kavala, Greece.
Fisheries Research Institute (HAO-DEMETER), 640 07, Nea Peramos, Kavala, Greece; Department of Botany, School of Biology, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece.
Mar Environ Res. 2020 Jun;158:104948. doi: 10.1016/j.marenvres.2020.104948. Epub 2020 Mar 10.
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.
在潮间带上区生长的海草床中，高盐度和强风浪的生境条件有利于大型底栖动物的生长，这些动物反过来又会促进沉积物的再悬浮，从而增加营养物质的供应。在低潮水期间，地中海的海草床中的海洋草 Cymodocea nodosa 和绿藻 Ulva rigida 会暴露在空气中。我们比较了有和没有附生植物的 C. nodosa 叶片以及 U. rigida 的脱水系数 (k) 和光合作用性能 (ΔF/Fm')。通过再浸泡后 ΔF/Fm'来评估这两个物种的恢复能力。脱水性系数 (k) 在三种大型植物材料之间差异显著 (p < 0.01)，而 C. nodosa 叶片上有附生植物和 U. rigida 的 k 值最低。对于所有材料，ΔF/Fm'随 RWC 的降低而显著下降，而 U. rigida 与其他两种材料的生理响应存在显著差异。与 C. nodosa 叶片相比，U. rigida 的藻体片段具有更高的耐旱性，其在 75%脱水程度下的 ΔF/Fm'在再浸泡 30 分钟后达到初始值，而 C. nodosa 仅达到 50%。本研究为这两个物种在不同干旱情景下的分布可能发生的变化提供了有价值的信息。
