Direct and indirect effects of high pCO2 on algal grazing by coral reef herbivores from the Gulf of Aqaba (Red Sea)
Direct and indirect effects of high pCO2 on algal grazing by coral reef herbivores from the Gulf of Aqaba (Red Sea)
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DOI：
10.1007/s00338-013-1066-5
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发表时间：
2013-12-01
期刊：
影响因子：
3.5
通讯作者：
Fine, M.
中科院分区：
文献类型：
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作者：
Borell, E. M.;Steinke, M.;Fine, M.
捕食海洋大型藻类是珊瑚礁群落的一个关键结构过程。然而，大气二氧化碳浓度上升导致的海洋酸化预计将对许多海洋动物产生不利影响，而海藻群落可能会受益并繁荣发展。我们测试了暴露在不同的PCO(2)(400、1,800和4,000亩大气压)下如何影响来自亚喀巴湾(红海)北部珊瑚礁的草食性鱼类和海胆对绿藻Lactuca的捕食，无论是直接通过改变草食动物的行为，还是间接通过改变藻类的适口性。我们还测定了PCO(2)对藻类组织中蛋白质和放牧威慑次生代谢物二甲基磺酸丙酸酯(DMSP)浓度的影响。在实验室和现场进行了一系列多选择摄食实验，分别在14d(藻类)和28d(草食动物)暴露后测试了放牧偏好和总摄食量。4,000亩ATM对生菜的生化组成和适口性有显著影响。与400亩ATM(对照)相比，1800亩没有观察到影响。莴苣暴露在4000亩ATM下，蛋白质含量显著下降，DMSP浓度显著升高。这与海胆Tripneustes gratlla和不同草食性鱼类(棘藻科、Siganidae和Pomacanthidae)对这些藻类的偏好减少不谋而合。在实验室条件下，没有观察到兔鱼的摄食偏好。暴露于高水平的PCO(2)并不直接影响锥虫和河豚对藻类的总摄取量。我们的结果表明，二氧化碳有可能改变藻类对不同草食动物的适口性，这可能对藻类丰度和珊瑚群落结构产生重要影响。然而，只有在4,000亩大气压的PCO(2)上才能观察到PCO(2)的影响，这一事实表明，在不久的将来，藻类与食草动物的相互作用可能会对预测的PCO(2)浓度产生阻力。
Grazing on marine macroalgae is a key structuring process for coral reef communities. However, ocean acidification from rising atmospheric CO2 concentrations is predicted to adversely affect many marine animals, while seaweed communities may benefit and prosper. We tested how exposure to different pCO(2) (400, 1,800 and 4,000 mu atm) may affect grazing on the green alga Ulva lactuca by herbivorous fish and sea urchins from the coral reefs in the northern Gulf of Aqaba (Red Sea), either directly, by changing herbivore behaviour, or indirectly via changes in algal palatability. We also determined the effects of pCO(2) on algal tissue concentrations of protein and the grazing-deterrent secondary metabolite dimethylsulfoniopropionate (DMSP). Grazing preferences and overall consumption were tested in a series of multiple-choice feeding experiments in the laboratory and in situ following exposure for 14 d (algae) and 28 d (herbivores). 4,000 mu atm had a significant effect on the biochemical composition and palatability of U. lactuca. No effects were observed at 1,800 relative to 400 mu atm (control). Exposure of U. lactuca to 4,000 mu atm resulted in a significant decrease in protein and increase in DMSP concentration. This coincided with a reduced preference for these algae by the sea urchin Tripneustes gratilla and different herbivorous fish species in situ (Acanthuridae, Siganidae and Pomacanthidae). No feeding preferences were observed for the rabbitfish Siganus rivulatus under laboratory conditions. Exposure to elevated pCO(2) had no direct effect on the overall algal consumption by T. gratilla and S. rivulatus. Our results show that CO2 has the potential to alter algal palatability to different herbivores which could have important implications for algal abundance and coral community structure. The fact that pCO(2) effects were observed only at a pCO(2) of 4,000 mu atm, however, indicates that algal-grazer interactions may be resistant to predicted pCO(2) concentrations in the near future.