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.

我们对气候如何变化的直接记录仅限于相对较近的一段时间，在那段时间里，已经部署了校准仪器（温度计、湿度计、风向标等）。这一仪器记录涵盖了过去100-150年。如果我们想利用过去气候的巨大变化来更好地理解系统是如何工作的，我们需要能够记录我们所关心的变量的“代理”的档案。毫无疑问，海洋历史气候最成功的档案来自于分泌碳酸钙的生物的外壳。有孔虫和球石等开放海洋生物的贝壳构成了海底沉积物的很大一部分。档案还包括珊瑚和软体动物每年的带状骨骼。然而，所有这些都通过生物矿化过滤纳入了过去气候的代理（例如，Mg/Ca作为温度计）。这些生物仅以部分已知的方式改变其骨骼的化学成分，而这些“重要影响”阻碍了我们解码过去气候变化的能力。该项目旨在通过结合良好的观察结果和最新成功的钙化过程模型，更好地了解这种生物矿化过程。这个项目将重点关注深海珊瑚，因为这些动物生活在一个今天变化不大的环境中。这使它们成为一个很好的“实验室老鼠”，因为我们可以在野外研究现代生物，并且仍然有对照实验。该项目的更广泛影响包括支持研究生直接从事研究工作，并通过公开讲座和视频向更广泛的受众进行宣传。深海珊瑚石竹具有规则的带状分布，地球化学示踪值与带状分布相关。这些模式，以及档案的普遍性和实用性，使该物种成为进一步开发示踪剂的理想目标。在近乎恒定的条件下生长，这种珊瑚骨架内稳定同位素和Me/Ca比率的变化只能归因于“重要影响”。本项目将采用双管齐下的方法开发更好的石竹体温计和碳酸盐体系代用品。现有的现代样本收集包含41个个体，范围广泛的温度，碳酸盐和磷酸盐浓度。使用多元素ICP-MS方法对Li， B, Mg, Ca, Sr， Ba和U进行大量测量，将给出骨架与海水之间的经验关系。使用SIMS和NanoSIMS对单个骨架进行微观分析将阐明地球化学的内部结构并添加del11B。珊瑚细胞外钙化液生物矿化过程的新模型表明，该模型可以正确预测石竹中del18O和del13C与多种海洋钙化物之间的线性关系。该项目将扩展该模型，包括Me/Ca比率，并针对SIMS和批量分析观察进行测试。该项目的目标是通过改进生物矿化过程的表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.