Ocean Acidification: Collaborative Research: The response of calcareous nannoplankton to ocean acidification during the Paleocene-Eocene thermal maximum

海洋酸化：合作研究：古新世-始新世热最大值期间钙质超小型浮游生物对海洋酸化的响应

• 批准号: 1415958
• 负责人: James Zachos
• 金额: $ 25.56万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1415958&HistoricalAwards=false
• 关键词: Ocean; Acidification; Collaborative; Research; response

One of the most significant threats for marine organisms is acidification as a result of unabated anthropogenic CO2 emission. On a global scale, acidification has the potential to impact biota that make their shells out of the minerals aragonite and calcite, that have a hard time forming shells in low pH waters. One such group, the calcareous nannoplankton (haptophyte algae including coccolithophores that build shells of the mineral calcite), are a vital part of the open-ocean food chain. Laboratory experiments suggest that coccolithophores can adapt to more acidic conditions, but whether the group can adapt in the natural environment is uncertain. The geological record contains a series of natural experiments that allow us to address the biological response of nannoplankton to greenhouse gas perturbations. The Paleocene-Eocene thermal maximum (PETM), a ~200,000 year long transient warming event 56 million years ago, is likely the best ancient model for the impact of massive greenhouse gas on marine ecosystems. Studies of nannoplankton from deep-sea sites show new taxa during the PETM including an increase in malformed morphotypes that could signify adaptation to lower calcite saturation. Moreover, geochemical evidence suggests a similar magnitude pH decline during the initial stages of the event as projected to occur in the 21st century. The insight gained from this study will complement modern experimental and ecological studies, allowing mapping of the impact of progressive carbonate undersaturation on the ancestors of modern nannoplankton through space and time. In addition to better understanding the long-term consequences of ocean acidification, broader impacts include training of students at the graduate and undergraduate level, support of a postdoctoral researcher, and outreach to K-12 classrooms.Much of the information on the PETM derives from the study of cores drilled in the deep sea. However, as the deep ocean also acidified during the event, the key early stage of the PETM and likely when the maximum surface ocean acidification took place, calcium carbonate has been dissolved in most deep-sea locations. Thus to study the full impact of ocean acidification on nannoplankton, this research focuses on nannoplankton contained within sedimentary sections deposited at continental shelf water depths. A superb opportunity to explore the impact of ocean acidification on PETM plankton exists in cores from the shelf on the Atlantic Coastal Plain where some of the shallowest and most expanded records of the event are found. These core sections offer high temporal resolution and preserve a high-fidelity record of the early part of the PETM. This project will use new and existing cores from Maryland and New Jersey to study the development and impact of acidification on the coastal ocean over millennial time scales. The goal is to address the following hypotheses: (1) Surface ocean carbonate saturation reached a minimum within the first twenty thousand years of the PETM then slowly recovered; (2) The response of nannoplankton to surface acidification was systematic with existing species tolerant of low saturation increasing in abundance followed by the evolution of new species and morphotypes; and (3) Eutrophication in the coastal ocean amplified the impact of acidification locally and played a critical role in drawing down CO2 during the early stages of the PETM. These hypotheses will be addressed using closely integrated: (a) nannoplankton assemblage studies to determine how species composition and morphology changed; (b) a suite of inorganic and organic proxies to elucidate the nature of environmental changes and particularly to unravel acidification from temperature signals; and (c) models to simulate the temporal variability of pH, saturation state and eutrophication on the shelf.

海洋生物最重要的威胁之一是由于人为二氧化碳的发射不足而导致的酸化。 在全球范围内，酸化有可能影响生物群，从而使其壳从矿物矿物和方解石中产生，这些壳在低pH水域中很难形成壳。 这样的一组，即钙质的Nannoplankton（包括生成矿物方解石壳的甲状腺藻类藻类）是开放态食物链的重要组成部分。实验室实验表明，球藻可以适应更酸性的条件，但是该组是否可以在自然环境中适应。 地质记录包含一系列自然实验，使我们能够解决Nannoplankton对温室气体扰动的生物学反应。古新世 - 新世热最大值（PETM）是5600万年前的约20亿年级短暂变暖事件，可能是大型温室气体对海洋生态系统影响的最佳古老模型。深海站点的Nannoplankton的研究显示了PETM期间的新分类单元，包括畸形的形态型的增加，这可能表明适应性降低方解石饱和度。 此外，地球化学证据表明，在事件的初始阶段，pH值类似，预计在21世纪发生。从这项研究中获得的洞察力将补充现代实验和生态研究，从而可以通过时空和时间和时间来映射渐进式碳酸盐的不饱和对现代Nannoplankton祖先的影响。 除了更好地了解海洋酸化的长期后果外，更广泛的影响还包括对研究生和本科生的学生培训，支持博士后研究人员的支持，以及向K-12教室进行宣传。有关PETM信息的信息来自于深海钻探核心的研究。 然而，随着事件期间深海也酸化，PETM的关键早期阶段以及最大表面海洋酸化时，碳酸钙已在大多数深海位置溶解。因此，为了研究海洋酸化对Nannoplankton的全部影响，这项研究的重点是沉积在大陆架水深沉积的沉积切片中包含的Nannoplankton。一个极好的机会来探索海洋酸化对PETM浮游生物的影响，从岩心中存在于大西洋沿海平原上的架子中，那里发现了一些最浅，最膨胀的事件记录。 这些核心部分提供了高时间分辨率，并保留了PETM早期的高保真记录。 该项目将利用马里兰州和新泽西州的新核心和现有核心研究千禧一代尺度上酸化对沿海海洋的发展和影响。 目的是解决以下假设：（1）表面海洋碳酸盐饱和度达到了PETM的前2-万年，然后缓慢恢复； （2）Nannoplankton对表面酸化的反应是系统的，现有的物种耐受性低的丰度增加，随后是新物种和形态型的演变； （3）沿海海洋中的富营养化在局部酸化的影响，在PETM的早期阶段降低二氧化碳方面起着至关重要的作用。 这些假设将使用紧密整合：（a）Nannoplankton组合研究，以确定物种组成和形态如何改变； （b）一套无机和有机代理，以阐明环境变化的性质，尤其是从温度信号中解散酸化的性质； （c）模拟架子上pH，饱和状态和富营养化的时间变化的模型。