Collaborative Research: Did small, non-fossilizing plankton dominate primary productivity and shape the recovery of calcareous plankton after the end Cretaceous mass extinction?

合作研究：小型非化石浮游生物是否在白垩纪末期大规模灭绝后主导了初级生产力并影响了钙质浮游生物的恢复？

• 批准号: 2037750
• 负责人: Julio Sepulveda
• 金额: $ 39.83万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2037750&HistoricalAwards=false
• 关键词: Collaborative; Research; Did; small; non

Phytoplankton, which live in the surface ocean, produce organic matter from sunlight and carbon dioxide. This primary production forms the base of most marine food webs and is a critical part of the global carbon cycle. In the modern ocean plankton are being impacted by warming and ocean acidification. Natural changes in ocean temperature and chemistry in the geologic past can help us understand the long-term effects of stressors such as warming and acidification. The Cretaceous-Paleogene (K-Pg) mass extinction event ~66 million years ago was one such time of global change. Calcareous (fossil-forming) nanoplankton were one of the dominant primary producers in the Cretaceous ocean. However, 93% of species of this group went extinct at the K-Pg boundary, and they were never again as dominant. Previous studies of the plankton response to the K-Pg event have generally been limited to studies of species which leave a physical fossil record. Thus, these studies provided only a partial view of ancient plankton ecosystems. The proposed work will overcome this limitation by using chemical fossils called biomarkers. These new data will be used together with traditional physical fossils to reconstruct changes in the marine plankton community following the K-Pg event. It has often been assumed that non-fossilizing phytoplankton filled the gap left by the decline in calcareous nannoplankton. This study will help test that hypothesis. Documenting the changes in both non-fossilizing and fossilizing plankton will improve our understanding of long-term changes in plankton ecology, and of how those changes could alter the ocean carbon cycle. This project will train early career researchers and undergraduate students, and will disseminate results to broader audiences through outreach and educational activities in partnership with organizations and programs in Austin, TX and Boulder, CO.The project will develop datasets of lipid biomarkers, calcareous nannoplankton, and planktic foraminifera from 5 sites in Tunisia, Spain, and the US Gulf Coast. Three sites in Tunisia (El Kef, Elles, and El Melah) represent a depth transect on a continental shelf (paleodepths of 200-500 m), Caravaca represents deeper water (~600-1000 m), while Brazos represent a shallow shelf which will allow us to test regional variability between north Africa and the US Gulf Coastal Plain. These data will allow tests of the following hypotheses:1. A low-diversity assemblage of non-fossilizing phytoplankton bloomed in the aftermath of the K-Pg extinction, during the time of low diversity calcareous nannoplankton “disaster” assemblages.2. Subsequent recovery of calcareous nannoplankton diversity is associated with a decline in non-fossilizing phytoplankton.3. Shifts in the heterotrophic planktic foraminifera assemblages are tied to turnover in the whole autotrophic plankton assemblage.4. The post-extinction community of primary producers was dominated by smaller phytoplankton like algae and cyanobacteria, and would have increased carbon recycling in shallow waters and reduced carbon export to the deep sea.The study will improve our understanding of the recovery after the end Cretaceous mass extinction and in our overall understanding of the role of plankton ecology in marine ecosystem change. Additionally, reconstructing the whole plankton ecosystem, and not just the part that fossilizes, would represent a significant improvement of our toolkit to investigate ancient oceans.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.

生活在地面海洋中的浮游植物，从阳光和二氧化碳产生有机物。这种初级生产构成了大多数海洋食品网的基础，并且是全球碳循环的关键部分。在现代海洋浮游生物中，正在受到变暖和海洋化的影响。地质过去海洋温度和化学的自然变化可以帮助我们理解压力源（例如变暖和酸化）的长期影响。白垩纪 - 巴雷元（K-PG）质量扩展事件约6600万年前就是全球变化的一个时代。钙化（化石形成）纳米膨胀是白垩纪海洋中主要的原始生产商之一。但是，该群体中有93％在K-PG边界灭绝了，它们再也没有占主导地位。先前对浮游生物对K-PG事件的反应的研究通常仅限于对留下物理化石记录的物种的研究。这些研究仅提供了古代浮游生物生态系统的部分视图。拟议的工作将通过使用称为生物标志物的化学化石来克服这一限制。在K-PG活动之后，这些新数据将与传统的物理化石一起使用，以重建海洋浮游生物社区的变化。通常认为，非化学化浮游植物填补了钙质Nannoplankton的下降所留下的空白。这项研究将有助于检验该假设。记录非俄罗斯化和化石浮游生物的变化将提高我们对浮游生物生态的长期变化以及这些变化如何改变海洋碳循环的理解。该项目将培训早期的职业研究人员和本科生，并通过与奥斯汀，德克萨斯州奥斯汀和博尔德的组织和计划合作，通过外展和教育活动将结果传播到更广泛的观众。突尼斯（El Kef，Elles和El Melah）的三个地点代表了连续架子上的深度（200-500 m的古兴趣），卡拉瓦卡代表更深的水（〜600-1000 m），而Brazos则代表一个浅层架子，这将使我们能够测试北非和US Gulf Castal Plins之间的区域可变性。这些数据将允许测试以下假设：1。在低多样性的延伸后，在低多样性的钙质多样性的钙质钙质钙质Nannaplankton“灾难”组合中，非质量浮游植物的低多样性组合在K-PG扩展后开花。2。随后的钙质内膨胀多样性的恢复与非质化浮游植物的下降有关3。在整个自动营养浮游生物组合中，异养岩石有孔虫组合的转移与营业额相关。4。主要生产者的后灭界以藻类和蓝细菌等较小的浮游植物为主，并且会增加在浅水区域中的碳回收，并减少碳出口到深海的碳导出。该研究将提高我们对最终质量扩展和对浮游植物ecosology ecosology ecosypom ecosypom ecosypom ecosypom concosecomeptic ecosstom ecosypomecomecomeptom ecosystom ecosystom ecosystom ecosystom ecosystom ecosypom ecosystom ecosystom ecosystom ecosystom ecosysty ecosy ecosyst of consology consocy的理解。此外，重建整个浮游生物生态系统，而不仅仅是化石化的部分，将代表我们的工具包的重大改进，以调查古老的海洋。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子和广泛影响的评估来评估的珍贵支持。

项目成果

Stratigraphy of the Cretaceous/Paleogene (K/Pg) boundary at the Global Stratotype Section and Point (GSSP) in El Kef, Tunisia: New insights from the El Kef Coring Project

突尼斯埃尔凯夫全球层型剖面和点 (GSSP) 的白垩纪/古近纪 (K/Pg) 边界地层学：埃尔凯夫取芯项目的新见解

• DOI: 10.1130/b36487.1
• 发表时间: 2023
• 期刊: GSA Bulletin
• 作者: Jones, Heather L.;Westerhold, Thomas;Birch, Heather;Hull, Pincelli;Hédi Negra, M.;Röhl, Ursula;Sepúlveda, Julio;Vellekoop, Johan;Whiteside, Jessica H.;Alegret, Laia
• 通讯作者: Alegret, Laia