RAPID: Assessing the role of hurricanes and microbes in enhancing coastal sediment accumulation

超过六千万美国人生活在墨西哥湾和大西洋沿岸。美国的这些地区最容易受到飓风和海平面上升的影响。然而，稳定海岸线和增加沉积物堆积可以减少这些危害。这项研究探索了微生物如何影响特克斯和凯科斯群岛上一个无人居住的小岛——小龙柏香礁上的这些过程。2022年9月，菲奥娜飓风从该岛附近经过。本研究考察了飓风过后，微生物如何稳定泻湖和沿海地区的沉积物。这项研究的结果将通过与特克斯和凯科斯群岛环境和沿海资源部（DECR）的伙伴关系与当地社区分享。这项研究还为帮助社区稳定海岸线的干预措施提供了概念证明。这将增强抵御海平面上升和飓风强度增加的能力。该项目的教育影响更广泛，包括科罗拉多大学的一名研究生和加州大学伯克利分校的一名博士后参加了抽样旅行。这项研究追踪了微生物垫沉积物稳定和飓风角砾岩胶结在菲奥娜飓风恢复期间发生的反应，菲奥娜飓风于2022年9月以3级飓风的形式经过小龙骨礁附近。2022年6月之前的野外季节观测提供了飓风前的基线。拟开展的工作包括：(i)利用溶解O2、H2S和pH的微电极图谱来追踪地垫中地球化学梯度的重建，并通过16S rRNA基因测序来比较群落恢复与irma前后和fiona前的观测结果；（ii）安装小型地面高程表装置，以定量地跟踪一系列地点的草席生长的净厚度；（iii）重复原位显微镜观察和短期捕获和结合实验，以确定垫层对增加的沉积物的响应是否随时间变化而变化（即，新沉积物的输送是垂直增加的主要要求），或者垫层的响应是否随着生态系统的恢复而变化（即，飓风对微生物生态系统的扰动与沉积物的输送同样重要）；(4)现场飓风角砾岩岩化实验，测量岩化的时间尺度和微生物活性。这项工作将在2023年进行三个实地季节，允许在飓风扰动后的第一年对岛屿的反应进行短期（每日）和中期（长达数月）观察。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Over 60 million Americans live along the coasts of the Gulf of Mexico and Atlantic. These regions of the United States are the most vulnerable to hurricanes and sea level rise. However, stabilizing coastlines and increasing sediment accumulation can reduce these hazards. This study explores how microbes affect these processes on Little Ambergris Cay, a small uninhabited island in the Turks and Caicos Islands. In September 2022, Hurricane Fiona passed near the island. This study examines how microbes stabilize sediment in both lagoonal and coastal settings after the hurricane. Results from this study will be shared with local communities through partnership with the Turks and Caicos Islands Department of Environment and Coastal Resources (DECR). This study also provides proof of concept for interventions that could help communities stabilize their coastlines. This would enhance resilience against sea level rise and increasing hurricane intensity. The project educational Broader Impacts include participation of a graduate student from University of Colorado and a postdoc from University of California, Berkeley in the sampling trips.This study tracks responses of microbial mat sediment stabilization and cementation of hurricane breccias that occur during the recovery from Hurricane Fiona, which passed close to Little Ambergris Cay as a Category 3 hurricane in September 2022. Observations from a prior field season in June 2022 provide a pre-hurricane baseline. Proposed work includes: (i) microelectrode profiles of dissolved O2, H2S, and pH to track re-establishment of geochemical gradients in mats and 16S rRNA gene sequencing to compare community recovery to our pre/post-Irma and pre-Fiona observations; (ii) installation of small-scale surface elevation table devices to quantitatively track net thickness of mat growth in a suite of locations; (iii) repeated in situ microscopy observations and short-term trapping-and-binding experiments to determine whether mat response to added sediment is the same over time (i.e., the delivery of new sediment is the primary requirement for vertical accretion) or if the mat response changes as the ecosystem recovers (i.e., the hurricane perturbation to the microbial ecosystem is as important as the delivery of sediment); and (iv) in situ hurricane breccia lithification experiments to measure the timescale of lithification and the microbial activity present. This work will be carried out over three field seasons during 2023, allowing both short-term (daily) and medium-term (months-long) observations of the island response during the first year following hurricane perturbation.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.