CO_2驱动海洋酸化对角叉菜影响研究

Impacts of CO_2-driving Ocean Acidification on Macroalgae(Chondrus ocellatus)

在实验室构建大气CO2浓度升高的生态模拟系统,研究CO2驱动海洋酸化对大型海藻角叉菜(Chondrus ocellatus)的影响。7天实验结果显示,大气CO2浓度由正常387 mg/L左右升高至500 mg/L,促进角叉菜生长,实验系统中角叉菜生物量增加量和相对生长速率分别比对照系统的高出47.5%和47.9%;当CO2浓度升高至600 mg/L和800 mg/L,反而抑制角叉菜生长,实验期间实验系统中角叉菜生物量增加量和相对生长速率分别比对照系统的降低13.2%和13.5%(600 mg/L)、12.9%和13.3%(800 mg/L)。实验系统中,角叉菜的叶绿素a含量随CO2浓度升高逐渐降低,实验结束时叶绿素a含量分别为实验初始时的97.0%(P<0.05)(387 mg/L)、88.9%(500 mg/L)、82.9%(600 mg/L)和75.9%(800 mg/L);角叉菜的类胡萝卜素含量随CO2浓度升高逐渐增加,实验结束时类胡萝卜素含量分别为实验初始时的99.8%(P<0.05)(387 mg/L)、120.1%(500 mg/L)、131.9%(600 mg/L)和162.7%(800 mg/L)。研究表明大型红藻角叉菜通过减少合成叶绿素a以降低光合作用、增加合成类胡萝卜素以加强保护海藻细胞的方式适应海洋酸化;角叉菜生长受到大气CO2浓度升高致使海水中无机碳源增加和驱动海洋酸化正负两方面共同作用。

Laboratory simulation of ecological systems of rising atmospheric CO2 levels was conducted, highlighting the in-fluences of driving ocean acidification on macroalgae （C, ocellatus）. The results of the simulation experiment which involved four independent tests in seven days showed that CO2 concentration at 500 mg/L, risen from 387 mg/L, the normal level, growth of C. ocellatus was enhanced compared with that in the control tests, leading to the increased biomass （IB） rate of 47.5%, and the increased relative growth rate （RGR） of C. ocellatus 47.9%; however, when CO2 concentration rising to 600 ppm or 800 mg/L, growth of C. ocellatus was inhibited. It has been showed that with the increase of CO2 levels, Chl. a content of C. ocellatus gradually declined; in contrast, when CO2 levels were increased, carotenoid content of C. ocellatus gradually in- creased as well. Findings of the simulation study suggested that C. ocellatus attenuated its photosynthesis through reducing synthesis of Chl.a, and that inacroalgae cells could be protected by increasing synthesis of carotenoid for adapting to ocean acidification. In addition, growth of C. ocellatus was impacted by the synergetic effects of ocean acidification in both positive and negative ways, the higher HCO3 concentration due to increased CO2 resulted in more carbon sources for macroalgae growth, lower pH in oceanic surface waters was detrimental to macroalgae.