Influences of coral genotype and seawater pCO2 on skeletal Ba/Ca and Mg/Ca in cultured massive Porites spp. corals
Influences of coral genotype and seawater pCO2 on skeletal Ba/Ca and Mg/Ca in cultured massive Porites spp. corals
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DOI：
10.1016/j.palaeo.2018.06.015
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发表时间：
2018-09
期刊：
影响因子：
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通讯作者：
N. Allison;C. Cole;C. Hintz;K. Hintz;A. Finch
中科院分区：
文献类型：
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作者：
N. Allison;C. Cole;C. Hintz;K. Hintz;A. Finch
珊瑚骨骼中的Ba/Ca可以代替海水中的Ba/Ca，用来推断大洋上升流和陆源径流，而[Mg2+]与珊瑚的生物矿化有关。我们培养了3种大体成虫的大个体(直径12 cm)。在一系列海水pCO2上采集珊瑚样本，以测试大气中二氧化碳的变化如何影响骨骼中的Ba/Ca和Mg/Ca。对经过5个 月驯化后沉积的骨骼进行鉴定，并用二次离子质谱仪分析骨骼中的Ba/Ca和Mg/Ca。相同珊瑚基因的一些重复群体之间的骨骼镁/钙差异很大，这阻碍了基因和海水pCO2效应的鉴定。珊瑚文石：相同珊瑚基因的两个重复群体之间的海水BA/Ca分配系数(KDBa/Ca)没有显著差异。我们观察到不同地体之间的KDBa/Ca有很大的差异。珊瑚的基因分型与海水二氧化碳分压无关。这些变化与珊瑚的钙化、光合作用或呼吸速率无关，也与骨骼的Kdmg/Ca或Kdsr/Ca无关。海水pCO2对两种基因型的KDBa/Ca无显著影响，但在1P.luteage型中，750 μ大气压海水pCO2的KDBa/Ca显著高于180 μ大气压。不同种群间KDBa/Ca的基因型差异。在比较珊瑚之间的Ba/Ca比值时，海水Ba值的重建会产生很大的误差(~250%)。对低海水二氧化碳沉积的化石珊瑚样品的分析，与现代样品相比，可能低估了过去的海水BA/Ca和海洋上升流/淡水输入，但与观察到的珊瑚基因型之间的差异相比，影响较小。
Coral skeletal Ba/Ca is a proxy for seawater Ba/Ca, used to infer oceanic upwelling and terrigenous runoff while [Mg2+] is implicated in the control of coral biomineralisation. We cultured large individuals (>12 cm diameter) of 3 genotypes of massive adultPoritesspp. corals over a range of seawater pCO2to test how atmospheric CO2variations affect skeletal Ba/Ca and Mg/Ca. We identified the skeleton deposited after a 5 month acclimation period and analysed the skeletal Ba/Ca and Mg/Ca by secondary ion mass spectrometry. Skeletal Mg/Ca varies significantly between some duplicate colonies of the same coral genotype hampering identification of genotype and seawater pCO2effects. Coral aragonite:seawater Ba/Ca partition coefficients (KDBa/Ca) do not vary significantly between duplicate colonies of the same coral genotype. We observe large variations in KDBa/Ca between different massivePoritesspp. coral genotypes irrespective of seawater pCO2. These variations do not correlate with coral calcification, photosynthesis or respiration rates or with skeletal KDMg/Ca or KDSr/Ca. Seawater pCO2does not significantly affect KDBa/Ca in 2 genotypes but KDBa/Ca is significantly higher at 750 μatm seawater pCO2than at 180 μatm in 1P.luteagenotype. Genotype specific variations in KDBa/Ca between differentPoritesspp. could yield large errors (~250%) in reconstructions of seawater Ba when comparing Ba/Ca between corals. Analysis of fossil coral specimens deposited at low seawater pCO2, may underestimate past seawater Ba/Ca and ocean upwelling/freshwater inputs when compared with modern specimens but the effect is small in comparison with the observed difference between coral genotypes.