Botany and Plant Science, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland.
Botany and Plant Science, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland.
Mar Pollut Bull. 2018 Sep;134:27-37. doi: 10.1016/j.marpolbul.2017.12.057. Epub 2018 Jan 10.
Global warming is emerging as one of the most critical threats to terrestrial and marine species worldwide. This study assessed the effects of simulated warming events in culture on two seagrass species, Posidonia oceanica and Cymodocea nodosa, which play a key role in coastal ecosystems of the Mediterranean Sea. Changes in fatty acids as key metabolic indicators were assessed in specimens from two geographical populations of each species adapted to different in situ temperature regimes. Total fatty acid (TFA) content and composition were compared in C. nodosa and P. oceanica from natural populations and following exposure to heat stress in culture. After heat exposure, individuals of C. nodosa and P. oceanica adapted to colder temperatures in situ accumulated significantly more TFA than controls. For both species, the proportion of polyunsaturated fatty acids (PUFA) decreased, and the percentage of saturated fatty acids (SFA) increased significantly after the heat treatment. These results highlight that populations of both species living at warmest temperatures in situ were more thermo-tolerant and exhibited a greater capacity to cope with heat stress by readjusting their lipid composition faster. Finally, exposure of seagrasses to warmer conditions may induce a decrease in PUFA/SFA ratio which could negatively affect their nutritional value and generate important consequences in the healthy state of next trophic levels.
全球变暖正成为全球陆地和海洋物种面临的最关键威胁之一。本研究评估了模拟变暖事件对两种海草物种——海洋波叶菊（Posidonia oceanica）和地中海真海枣（Cymodocea nodosa）——的影响，这两种海草在地中海沿海生态系统中起着关键作用。研究人员评估了适应不同原位温度条件的两个物种的两个地理种群标本中的脂肪酸变化作为关键代谢指标。比较了自然种群中海枣树和海洋波叶菊的总脂肪酸（TFA）含量和组成，并在培养过程中暴露于热应激下。热暴露后，与对照组相比，原位温度较低的 C. nodosa 和 P. oceanica 个体积累的 TFA 明显更多。对于这两个物种，多不饱和脂肪酸（PUFA）的比例下降，饱和脂肪酸（SFA）的百分比在热处理后显著增加。这些结果表明，生活在原位温度最高的两个物种的种群具有更强的耐热性，并且通过更快地调整其脂质组成来应对热应激的能力更强。最后，海草暴露在温暖条件下可能会导致 PUFA/SFA 比例降低，这可能会对它们的营养价值产生负面影响，并对下一营养级的健康状态产生重要影响。
