Horwitz Rael, Borell Esther M, Yam Ruth, Shemesh Aldo, Fine Maoz
1] The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel [2] The Interuniversity Institute for Marine Sciences, P.O. Box 469, Eilat 8810300, Israel.
The Interuniversity Institute for Marine Sciences, P.O. Box 469, Eilat 8810300, Israel.
Sci Rep. 2015 Mar 5;5:8779. doi: 10.1038/srep08779.
Contemporary cnidarian-algae symbioses are challenged by increasing CO2 concentrations (ocean warming and acidification) affecting organisms' biological performance. We examined the natural variability of carbon and nitrogen isotopes in the symbiotic sea anemone Anemonia viridis to investigate dietary shifts (autotrophy/heterotrophy) along a natural pCO2 gradient at the island of Vulcano, Italy. δ(13)C values for both algal symbionts (Symbiodinium) and host tissue of A. viridis became significantly lighter with increasing seawater pCO2. Together with a decrease in the difference between δ(13)C values of both fractions at the higher pCO2 sites, these results indicate there is a greater net autotrophic input to the A. viridis carbon budget under high pCO2 conditions. δ(15)N values and C/N ratios did not change in Symbiodinium and host tissue along the pCO2 gradient. Additional physiological parameters revealed anemone protein and Symbiodinium chlorophyll a remained unaltered among sites. Symbiodinium density was similar among sites yet their mitotic index increased in anemones under elevated pCO2. Overall, our findings show that A. viridis is characterized by a higher autotrophic/heterotrophic ratio as pCO2 increases. The unique trophic flexibility of this species may give it a competitive advantage and enable its potential acclimation and ecological success in the future under increased ocean acidification.
当代刺胞动物与藻类的共生关系正受到二氧化碳浓度上升（海洋变暖和酸化）的挑战，这影响着生物的生物学性能。我们研究了共生海葵绿海葵中碳和氮同位素的自然变异性，以调查意大利武尔卡诺岛沿自然pCO₂梯度的饮食转变（自养/异养）。随着海水pCO₂的增加，绿海葵的藻类共生体（共生藻）和宿主组织的δ(¹³)C值均显著变轻。再加上在较高pCO₂位点时两个部分的δ(¹³)C值之间的差异减小，这些结果表明在高pCO₂条件下，绿海葵的碳预算中有更大的净自养输入。沿着pCO₂梯度，共生藻和宿主组织中的δ(¹⁵)N值和C/N比没有变化。其他生理参数显示，各站点之间海葵蛋白质和共生藻叶绿素a保持不变。各站点之间共生藻密度相似，但在pCO₂升高的情况下，海葵中的共生藻有丝分裂指数增加。总体而言，我们的研究结果表明，随着pCO₂的增加，绿海葵的特征是自养/异养比更高。该物种独特的营养灵活性可能使其具有竞争优势，并使其在未来海洋酸化加剧的情况下有可能适应环境并在生态上取得成功。
