Collaborative Research: Biologically-driven island-building during sea-level rise and its implications for promoting resilient coastlines

由于气候变化，沿海地区面临洪水和侵蚀的高风险。红树林通过捕获被称为泥浆的小沉积物来帮助保护海岸线。泥层的堆积抵消了海平面的上升。这个项目将研究微生物垫的沉积物捕获，微生物层状群落。微生物垫在红树林生态系统中很常见，以前的研究表明，微生物垫可以捕获比红树林更大的沉积物。pi假设微生物垫可能在捕获沙粒大小的沉积物中起着重要但未被重视的作用。这将通过实地观察和建模来测试，以了解微生物垫是否有助于在三个研究地点建立紧急土地。结果将用于评估在更广泛的沿海管理实践中考虑微生物垫是否有用。将制作一部教育短片，介绍该项目的主要结论，并与当地社区和广大公众分享。该项目还将为高中生和研究生提供培训。PIs将测试这样一个假设：微生物垫可以增强红树林的粮食捕获效应，导致粗沉积物的积累和早期胶结，从而使海岸能够抵御海平面上升和飓风强度增加。主要的研究地点是小龙骨礁（LAC），这是特克斯和凯科斯群岛上一个无人居住的岛屿，在过去的大约一万年中逐渐增加，其特征是厚厚的微生物垫，碳酸盐胶结的硬地和红树林灌木丛，其底层沉积物主要由海水沉淀形成的碳酸盐沙粒组成。该项目将采用多学科方法来研究海平面上升期间生物学如何对紧急地形的构建做出贡献，并评估如何将所涉及的过程应用于增强其他地区的沿海复原力。该项目将由四个部分组成：(1)微生物垫稳定沉积物的速率和机制的实时观测；(2)分析1万年全新世沉积记录，评估沉积物堆积速率和空间变化；(3)泥沙运移建模，用于重建岛屿的发展，以测试当地的水动力和无机胶结作用是否足以形成所观察到的紧急地形，或者，如果需要生物影响，也可以这样做；(4)将拉美和加勒比地区的微生物群落和沉积物积累模式与两个不同的海岸系统（一个在佛罗里达群岛，一个在伯利兹）进行比较，以确定拉美和加勒比地区独特的生态与其他海岸线的关系。除了评估微生物垫与红树林的相互作用以及沉积物运输动力学是否会影响海平面上升风险的沿海地区的沉积物积聚外，该项目还将有助于了解红树林相关微生物群落的多样性、活动和形态。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。

Coastal regions are at high risk for flooding and erosion due to climate change. Mangroves help protect coastlines by trapping small sediment called mud. The accumulation of mud layers counteracts sea-level rise. This project will examine sediment trapping by microbial mats, layered communities of microorganisms. Microbial mats are common in mangrove ecosystems and previous research has shown that microbial mats can trap larger sediment than mangroves. The PIs hypothesize that microbial mats may be playing an important but under-appreciated role in trapping sand-sized sediment. This will be tested using field observations and modeling to understand whether microbial mats helped build emergent land in three study sites. Results will be used to evaluate whether it is useful to consider microbial mats in coastal management practices more broadly. A short educational film featuring the key conclusions of this project will be shared with local communities and the broader public. This project will also provide training to high school and graduate students.The PIs will test the hypothesis that microbial mats can augment grain-trapping effects of mangroves, resulting in the accumulation and early cementation of coarse sediment that makes coasts resilient to sea-level rise and increased hurricane intensities. The primary study site is Little Ambergris Cay (LAC), an uninhabited island in the Turks and Caicos Islands that accreted over approximately the last 10,000 years, characterized by thick microbial mats, carbonate-cemented hardgrounds, and mangrove thickets with underlying sediment dominantly composed of ooids, carbonate sand grains that form via precipitation from seawater. The project will apply a multidisciplinary approach to examine how biology contributed to the construction of emergent topography during sea-level rise and evaluate how the processes involved could be applied to enhance coastal resiliency in other areas. The project will consist of four components: (1) real-time observations of rates and mechanisms of sediment stabilization by microbial mats; (2) analysis of a 10,000 year, Holocene, depositional record to assess rates and spatial variations in sediment accumulation; (3) sediment transport modeling to reconstruct island development to test whether local hydrodynamics and inorganic cementation are sufficient to create the emergent topography observed or, alternately, if biological influence is required; and (4) comparing LAC microbial community and sediment accumulation patterns with two contrasting coastal systems (one in the Florida Keys and one in Belize) to identify how the unique ecology of LAC relates to other coastlines. In addition to evaluating whether the interactions of microbial mats with mangroves and sediment transport dynamics affect sediment accumulation in coastal regions at risk from rising sea-level, this project will also contribute to understanding of the diversity, activity, and morphology of mangrove-associated microbial communities.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.