Biomineralization in Deep-sea Corals: Empirical Tracer Calibration Coupled to a Mechanistic Model of Skeletal Growth

深海珊瑚的生物矿化：经验示踪剂校准与骨骼生长机制模型相结合

• 批准号: 1737404
• 负责人: Jess Adkins
• 金额: $ 43.67万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1737404&HistoricalAwards=false
• 关键词: Biomineralization; Deep; sea; Corals; Empirical

Our direct record of how the climate has changed is limited to the relatively recent period of time where calibrated instruments (thermometers, hygrometers, wind vanes, etc.) have been deployed. This instrumental record covers the last 100-150 years. If we want to exploit the large changes in past climate to better understand how the system works, we need archives capable of recording 'proxies' of the variables we care about. Far and away the most successful archive of past climate from the oceans comes from the shells of calcium carbonate secreting organisms. Shells from open ocean dwellers like foraminifera and coccoliths make up a large percentage of the seafloor sediments. Archives also include the annually banded skeletons of corals and mollusks. However, all of these incorporate proxies for past climate (Mg/Ca as a thermometer for instance) through the filter of biomineralization. These organisms modify the chemistry of their skeletons in only partially known ways, and these 'vital effects' hinder our ability to decode how climate has changed in the past. This project aims to better understand this biomineralization process through a combination of well-posed observations and a newly successful model of the calcification process. This project will focus on deep-sea corals because these animals live in an environment today that does not change very much. This makes them a good 'lab rat' since we can study a modern organism in the wild and still have controlled experiments. The broader impacts of this project include support for a graduate student to work directly on the research and outreach through public lectures and videos to reach a wide range of audiences.The deep-sea coral D. dianthus has a regular banding pattern and correlated geochemical tracer values that follow the banding. These patterns, and the ubiquity and usefulness of the archive, make this species an ideal target for further tracer development. Growing in near constant conditions, variations in stable isotopes and Me/Ca ratios within this coral's skeleton can only be due to 'vital effects'. This project will develop better thermometers and carbonate system proxies in D. dianthus using a two-pronged approach. The existing modern sample collection contains 41 individuals from a wide range of temperature, carbonate and phosphate concentrations. Bulk measurements of Li, B, Mg, Ca, Sr, Ba, and U using a multi-element ICP-MS method will give the empirical relationship between skeleton and seawater. Microanalysis of individual skeletons using SIMS and NanoSIMS will elucidate the internal structure of the geochemistry and add del11B. A new model of the biomineralization process in the coral's Extracellular Calcifying Fluid shows that it can correctly predict the linear relationship between del18O and del13C seen in D. dianthus and a wide array of marine calcifiers. This project will expand this model to include Me/Ca ratios and to test it against the SIMS and bulk analysis observations. The goal of the project is to create better tracers through improved characterization of the biomineralization process. While the model is already showing its worth, the plan to collect an empirical modern sample calibration dataset ensures that it can also improve modern calibrations.

我们对气候变化的直接记录仅限于经过校准的仪器(温度计、湿度计、风叶等)相对较近的一段时间。已经部署好了。这一乐器记录涵盖了过去100-150年的时间。如果我们想要利用过去气候的巨大变化来更好地理解这个系统是如何工作的，我们需要能够记录我们所关心的变量的“替代物”的档案。海洋过去气候的最成功记录无疑来自碳酸钙分泌生物体的外壳。有孔虫和球石等远洋生物的贝壳构成了海底沉积物的很大比例。档案还包括每年一次的珊瑚和软体动物带状骨骼。然而，所有这些都包含了过去气候的替代品(例如，作为温度计的镁/钙)，通过生物矿化的过滤器。这些生物只以部分已知的方式改变其骨骼的化学成分，这些“重要影响”阻碍了我们破译过去气候变化的能力。这个项目旨在通过良好的观察和一个新成功的钙化过程模型相结合来更好地理解这种生物矿化过程。这个项目将专注于深海珊瑚，因为这些动物生活在今天没有太大变化的环境中。这使它们成为一只很好的“实验室老鼠”，因为我们可以在野外研究现代生物体，而且仍然可以进行对照实验。该项目的更广泛影响包括支持一名研究生通过公开讲座和视频直接从事研究和外联工作，以接触到广泛的受众。深海珊瑚石珊瑚具有规则的带状图案和遵循带状图案的相关地球化学示踪值。这些模式，以及档案的无处不在和有用，使该物种成为进一步示踪开发的理想目标。在近乎恒定的生长条件下，这种珊瑚骨骼中稳定同位素和Me/Ca比值的变化只能是“生命效应”造成的。该项目将采用双管齐下的方法，在石竹中开发更好的温度计和碳酸盐体系代理。现有的现代样本收集包含41个个体，来自广泛的温度、碳酸盐和磷酸盐浓度。用多元素电感耦合等离子体质谱(ICP-MS)方法对锂、硼、镁、钙、锶、钡、铀等元素进行批量测量，可以得到骨骼与海水之间的经验关系。使用SIMS和NanoSIMS对单个骨骼进行微观分析将阐明地球化学的内部结构，并添加del11B。一个新的珊瑚细胞外钙化流体中生物矿化过程的模型表明，它可以正确地预测在石竹和一系列海洋钙化物质中看到的del18O和del13C之间的线性关系。该项目将扩展该模型以包括Me/Ca比率，并根据SIMS和整体分析观察对其进行测试。该项目的目标是通过改进生物矿化过程的特征来创造更好的示踪剂。虽然该模型已经显示出其价值，但收集经验现代样本校准数据集的计划确保了它也可以改进现代校准。

项目成果

Carbonic anhydrase, coral calcification and a new model of stable isotope vital effects

• DOI: 10.1016/j.gca.2018.02.032
• 发表时间: 2018-09-01
• 期刊: GEOCHIMICA ET COSMOCHIMICA ACTA
• 影响因子: 5
• 作者: Chen, Sang;Gagnon, Alexander C.;Adkins, Jess F.
• 通讯作者: Adkins, Jess F.

A Cenozoic record of seawater uranium in fossil corals

珊瑚化石中海水铀的新生代记录

• DOI: 10.1016/j.gca.2019.01.039
• 发表时间: 2019
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Gothmann, Anne M.;Higgins, John A.;Adkins, Jess F.;Broecker, Wally;Farley, Kenneth A.;McKeon, Ryan;Stolarski, Jarosław;Planavsky, Noah;Wang, Xiangli;Bender, Michael L.
• 通讯作者: Bender, Michael L.