Improving High Latitude Foraminiferal Paleoproxies: Insights from Northern California Current Modern and Historical Records

改善高纬度有孔虫古代理：来自北加州当前现代和历史记录的见解

• 批准号: 2222365
• 负责人: Brittany Hupp
• 金额: $ 26.87万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2222365&HistoricalAwards=false
• 关键词: Improving; Latitude; Foraminiferal; Paleoproxies; Insights

This project will improve our ability to reconstruct past ocean conditions, such as sea surface temperatures, in high-latitude regions. These regions experience a more extreme response to climate change than low-latitude regions. One of the best ways to study past ocean-climate change is by studying fossil plankton called planktic foraminifera or “forams”. Forams are microscopic zooplankton that have existed for over 200 million years and live near the surface of the ocean. As these organisms grow, they build small shells. The shell chemistry records the conditions at the time the shells were formed. When the organism dies, its shell sinks to the seafloor and becomes part of the geological fossil record. Thus, the chemical composition of fossil shells recovered from deep-sea sediments can be used to reconstruct the surface ocean conditions in the past. This study will generate the geochemical-environmental relationships (i.e., calibration equations) used to evaluate fossil foram records. The composition of the shells of living and recently deceased forams collected from the surface ocean will be compared to the conditions and chemical makeup of the seawater they are living in. Samples for this study will include an archive of plankton tow samples from the last decade. Newly collected plankton tow and water samples from throughout the Northern California Current region off the coast of northern California, Oregon, and Washington states will also be studied. Although forams are found globally, this study will focus on constraining geochemical-environmental relationships for species that live in intermediate- to high-latitude regions to better predict how these vulnerable regions will respond to our changing climate. The research team will also investigate how the composition of foram shells may change throughout the organism’s life cycle. This study will help ensure that the calibration equations used to interpret fossil records are accurate. The project includes support for an early career scientist and for undergraduate students. The research team will share the results and scientific process of the research with the public through several public outreach events.The dynamic Northern California Current (NCC) system has been extensively monitored for nearly half a century, through a series of hydrographic transects off the coasts of California, Oregon, and Washington, resulting in a robust archive of plankton tow samples and concurrent environmental data. This study will use historical plankton tow samples, and collect new plankton samples, to further develop a range of trace element/calcium (TE/Ca) paleoproxies for intermediate to high latitude planktic foraminiferal species living in the NCC. Species common to the NCC include temperate and high-latitude genotypes of Globigerina bulloides, Neogloboquadrina pachyderma, N. incompta, N. dutertrei, and Turborotalita quinqueloba. These species are common in higher latitude regions, including the Artic Ocean, where temperature change in response to climate change tends to be greatest. The research objectives are to: 1) establish Mg/Ca-temperature and Na/Ca-salinity calibrations for understudied temperate to polar planktic foraminiferal taxa and investigate the potential for other TE/Ca-environmental relationships, 2) investigate potential vital effects and mechanisms for TE incorporation in planktic foraminiferal shells as they transition from life to death, and 3) characterize the d18O(seawater) signature in the study region and establish species specific seawater foraminiferal calcite isotopic offsets in order to constrain the depth habitats of the study taxa, a critical step to establishing calibrations based on data in a “natural laboratory” setting. The proposed research will further develop novel and existing planktic foraminiferal TE/Ca proxies for use in paleoclimatic and paleoceanographic reconstructions, with particular emphasis on improving our ability to reconstruct past environmental conditions in intermediate to high latitude regions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目将提高我们重建过去海洋状况的能力，例如高纬度地区的海面温度，这些地区比低纬度地区对气候变化的反应更为极端。气候变化是通过研究被称为浮游有孔虫或“有孔虫”的浮游生物化石来实现的。有孔虫是微小的浮游动物，已经存在了 2 亿多年，生活在海洋表面附近。随着这些生物体的生长，它们的体积越来越小。贝壳化学记录了贝壳形成时的条件，当生物死亡时，其贝壳沉入海底并成为地质化石记录的一部分，因此，从深海沉积物中回收了贝壳化石的化学成分。可用于重建过去的表面海洋状况。这项研究将生成地球化学-环境关系（即校准方程），用于评估从活体和最近死亡的有孔虫的壳的组成。将把表层海洋与它们所生活的海水的条件和化学成分进行比较。这项研究的样本将包括过去十年中新收集的浮游生物拖曳样本和来自整个北加州海流区域的水样本。尽管在全球范围内都发现了有孔虫，但这项研究将重点关注生活在中高纬度地区的物种的地球化学-环境关系，以更好地预测这些物种的地球化学与环境关系。脆弱地区将研究小组还将研究有孔虫壳的成分在生物体的整个生命周期中如何变化，该研究将有助于确保用于解释化石记录的校准方程是准确的。研究团队将通过几次公共宣传活动与公众分享研究结果和科学过程。近半个世纪以来，动态的北加州洋流 (NCC) 系统一直受到广泛监测。离海岸线不远的一系列水文横断面加利福尼亚州、俄勒冈州和华盛顿州，形成了丰富的浮游生物拖曳样本档案和同时存在的环境数据。本研究将使用历史浮游生物拖曳样本，并收集新的浮游生物样本，以进一步开发一系列微量元素/钙 (TE/Ca)。 ) 生活在 NCC 的中高纬度浮游有孔虫物种的古代表 NCC 常见的物种包括温带和高纬度基因型 Globigerina bulloides、Neogloboquadrina。这些物种在包括北冰洋在内的高纬度地区很常见，这些地区对气候变化的响应趋势最大。研究目标是：1) 确定。正在研究的温带至极地浮游有孔虫类群的 Mg/Ca 温度和 Na/Ca 盐度校准，并研究其他潜在TE/Ca-环境关系，2) TE 在浮游有孔虫壳从生到死的转变过程中掺入 TE 的潜在重要影响和机制，3) 表征研究区域的 d18O（海水）特征并建立物种特异性海水有孔虫方解石同位素偏移以限制研究类群的深度栖息地，这是根据“自然实验室”环境中的数据建立校准的关键步骤。进一步开发新型和现有的浮游有孔虫 TE/Ca 代理，用于古气候和古海洋重建，特别强调提高我们重建中高纬度地区过去环境条件的能力。该奖项反映了 NSF 的法定使命，并被认为值得通过使用基金会的智力优势和更广泛的影响审查标准进行评估来提供支持。