Sensitivity of planktic foraminiferal test bulk density to ocean acidification
Sensitivity of planktic foraminiferal test bulk density to ocean acidification
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DOI：
10.1038/s41598-019-46041-x
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发表时间：
2019-07-05
影响因子：
4.6
通讯作者：
Uchida, H.
中科院分区：
文献类型：
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作者：
Iwasaki, S.;Kimoto, K.;Uchida, H.
人为CO2在海洋中的积累降低了海水碳酸盐离子浓度，并可能降低海洋钙质生物的钙化率。根据南极有孔虫测试重量的几个替代指标已被用来评估海洋酸化对这些生物的影响。不幸的是，由于缺乏一种方法来评估测试的体积密度，海水碳酸盐化学对测试钙化的影响仍然没有完全了解。在这项研究中，我们测量了活的Globigerina bulloides（浮游有孔虫）测试的体积密度与X射线微计算机断层扫描（XMCT）扫描仪，并将其与周围海水的特性进行比较。结果表明，测试体积密度控制环境海水碳酸根离子浓度和测试体积密度的变化是伴随着变化的内部超微结构的微米至亚微米尺度的孔隙度。这些结果表明，由于环境海水酸化的有孔虫试验的体积密度的变化可以直接观察到的XMCT扫描。因此，钙化强度的一个有用指标是用XMCT对测试密度进行物理测量。
The anthropogenic CO2 accumulating in the ocean is lowering seawater carbonate ion concentration and may reduce calcification rates of marine calcareous organisms. Several proxies based on test weights of planktic foraminifera have been used to evaluate the impact of ocean acidification on these organisms. Unfortunately, because of the absence of a method to evaluate the bulk density of a test, the impact of seawater carbonate chemistry on test calcification is still not fully understood. In this study, we measured bulk densities of living Globigerina bulloides (planktic foraminifera) tests with an X-ray micro-computed tomography (XMCT) scanner and compared them with ambient seawater characteristics. Results demonstrated that test bulk densities were controlled by ambient seawater carbonate ion concentrations and that changes of test bulk densities were accompanied by changes in micron to submicron scale porosity of internal ultrastructure. These results suggest that alteration of the bulk density of foraminiferal tests due to acidification of ambient seawater can be directly observed by XMCT scanning. A useful metric of calcification intensity would therefore be physical measurements of test densities with XMCT.