Calibration of seawater temperature and δ 18Oseawater signals in Tridacna maxima's δ 18Oshell record based on in situ data
Calibration of seawater temperature and δ 18Oseawater signals in Tridacna maxima's δ 18Oshell record based on in situ data
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DOI：
10.1007/s00338-014-1245-z
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发表时间：
2015-06-01
期刊：
影响因子：
3.5
通讯作者：
Cabioch, G.
中科院分区：
文献类型：
--
作者：
Duprey, N.;Lazareth, C. E.;Cabioch, G.
巨蛤（Tridacna maxima）具有很强的古气候重建潜力，但其壳稳定氧同位素比值（δ O-18（贝壳））与海表温度（SST）和海水稳定氧同位素比值（δ O-18(sw)）之间的关系尚未标定，限制了其应用。在本研究中，用钙黄蛋白染色最大t鱼标本，并在水箱中培养1.5年。每周监测水箱海水的表面盐度，每小时记录海水的稳定氧同位素比值（δ O-18(sw)）和海温。壳层薄切片的显微观察显示出微观的、简单的和复杂的生长增量。染色实验表明，这些生长增量是每天沉积的。周δ O-18（壳）记录表明，壳在与海水的同位素平衡中沉淀，δ O-18（壳）- δ O-18（sw）变化的63%可以用海温变化来解释。将T. maxima高分辨率δ O-18（壳）记录、原位δ O-18（sw）和海表温度数据联系起来的常规线性函数(1)计算为：其中海表温度单位为摄氏度，δ δ O-18为壳与海水（δ O-18（壳）- δ O-18(sw)）稳定氧同位素比值之差，单位为欧度VPDB。由该方程重建的海表温度均方根误差为+/- 1.41℃，揭示了T. maxima在古气候研究中的潜力。通过对本研究和前人研究结果的综合整理，提出了巨蛤平均海温= f（δ O-18（壳）- δ O-18(sw)）方程，该方程允许从尚未校准的巨蛤物种或没有现代同种生物的化石巨蛤物种的同位素值中获得海温记录。
The giant clam Tridacna maxima presents a strong potential for paleoclimatic reconstructions but its use remains limited by the fact that the relationship between the shell stable oxygen isotopes ratio (delta O-18(shell)), the sea surface temperature (SST), and the stable oxygen isotopes ratio of seawater (delta O-18(sw)) has not been calibrated yet. In this study, a T. maxima specimen was stained with calcein and grown in a tank for 1.5 yr. The tank seawater was monitored weekly for sea surface salinity, and the stable oxygen isotopes ratio of seawater (delta O-18(sw)) and SST was recorded hourly. Microscopic observations of outer shell layer thin sections revealed micrometric, simple and complex, growth increments. The staining experiment demonstrated that these growth increments were deposited on a daily basis. The weekly delta O-18(shell) record showed that the shell was precipitated in isotopic equilibrium with seawater and that 63 % of the (delta O-18(shell) - delta O-18(sw)) variations were explained by SST variations. A conventional linear function (1) linking T. maxima high-resolution delta O-18(shell) record, in situ delta O-18(sw), and SST data was calculated as:where SST is in degree Celsius and Delta delta O-18 is the difference between the stable oxygen isotopes ratio of the shell and of the seawater (delta O-18(shell) - delta O-18(sw)), in aEuro degrees VPDB. The root mean square error of the SST reconstructed by this equation is +/- 1.41 A degrees C revealing the potential of T. maxima for paleoclimatic studies. An average SST = f(delta O-18(shell) - delta O-18(sw)) equation for giant clam is proposed by compiling the equations from the present study and previous worksThis equation permits one to obtain SST records from isotopic values of giant clams species that have not been calibrated yet or from fossil giant species that do not have living modern conspecifics.