The effect of ocean acidification on tropical coral calcification: Insights from calcification fluid DIC chemistry
The effect of ocean acidification on tropical coral calcification: Insights from calcification fluid DIC chemistry
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DOI：
10.1016/j.chemgeo.2018.09.004
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发表时间：
2018-10-10
期刊：
影响因子：
3.9
通讯作者：
Finch, Adrian
中科院分区：
文献类型：
--
作者：
Allison, Nicola;Cole, Catherine;Finch, Adrian
海洋酸化通常会减少热带海洋珊瑚的钙化，但这一过程的机制尚不清楚。我们使用骨骼硼地球化学（B/Ca和δ B-11）重建钙化流体DIC的珊瑚培养在高和低海水pCO（2）（180，400和750 μ大气压）。我们观察到钙化液pH值和可能与文石沉淀有关的DIC物质浓度之间存在强正相关性（无论是CO 32-、HCO 3-还是HCO 3- + CO 32-）。同样，除了一个异常值，沉淀DIC物种的流体浓度与珊瑚钙化率呈强正相关。在高海水pCO（2）下培养的珊瑚通常具有低钙化液pH值和低浓度的沉淀DIC，这表明钙化部位DIC底物的减少是钙化减少的原因。异常珊瑚在高海水pCO（2）下保持高pH值（CF）和DICCF，但钙化率降低，表明珊瑚的能量预算有限，无法支持质子从钙化液中排出，并满足其他钙化需求。我们没有发现增加海水pCO（2）会增强CO2扩散到钙化部位的证据。相反，海水pCO（2）处理之间可扩散到钙化部位的覆盖[CO2]似乎大致相当，这意味着代谢活动（呼吸和光合作用）在钙化部位附近产生类似的[CO2]，而不管海水pCO（2）。
Ocean acidification typically reduces calcification in tropical marine corals but the mechanism for this process is not understood. We use skeletal boron geochemistry (B/Ca and delta B-11) to reconstruct the calcification fluid DIC of corals cultured over both high and low seawater pCO(2) (180, 400 and 750 mu atm). We observe strong positive correlations between calcification fluid pH and concentrations of the DIC species potentially implicated in aragonite precipitation (be they CO32-, HCO3- or HCO3- + CO32-). Similarly, with the exception of one outlier, the fluid concentrations of precipitating DIC species are strongly positively correlated with coral calcification rate. Corals cultured at high seawater pCO(2) usually have low calcification fluid pH and low concentrations of precipitating DIC, suggesting that a reduction in DIC substrate at the calcification site is responsible for decreased calcification. The outlier coral maintained high pH(CF) and DICCF at high seawater pCO(2) but exhibited a reduced calcification rate indicating that the coral has a limited energy budget to support proton extrusion from the calcification fluid and meet other calcification demands. We find no evidence that increasing seawater pCO(2) enhances diffusion of CO2 into the calcification site. Instead the overlying [CO2] available to diffuse into the calcification site appears broadly comparable between seawater pCO(2) treatments, implying that metabolic activity (respiration and photosynthesis) generates a similar [CO2] in the vicinity of the calcification site regardless of seawater pCO(2).