Collaborative Research: NSF-BSF: Photophysiology and bio-optics of Red Sea mesophotic corals

热带珊瑚礁是生物多样性的热点，为全球众多沿海社区提供重要服务。全球和当地的压力因素导致了浅水珊瑚礁群落前所未有的退化。最重要的是，水温升高加上过量的太阳辐射会导致珊瑚白化，这描述了珊瑚共生藻类的损失，被认为是对浅水珊瑚礁未来存在的主要威胁。因此，来自深水的珊瑚越来越受到关注，因为它们有望缓冲在浅水中更常见的极端环境影响。令人惊讶的是，珊瑚在阳光几乎无法到达的栖息地茁壮成长，30-150米深度的中孔珊瑚礁生态系统（MCEs）以独特的珊瑚群落为特征，可以作为浅水珊瑚的避难所。在这个项目中，我们的目标是利用多学科方法，结合最先进的生物工程、生物光学和珊瑚生理学工具，研究允许珊瑚在这种光受限条件下茁壮成长的光收集机制。由于珊瑚是最有效的水生光合系统之一，研究珊瑚生物光学也可以导致发现新的光收集机制和开发新的珊瑚启发光子材料，以建立更有效和可持续的光生物反应器。这是一个美以两国项目，旨在通过一系列公共宣传活动促进国际合作和多样性，包括博物馆展览和创意体验设计，以支持代表性不足的群体参与STEM。光照是珊瑚群落沿珊瑚礁深度梯度变化的关键驱动因素。然而，辐照度对珊瑚生存和生长的重要性主要是在浅层物种中研究的，而中厚珊瑚如何在极其有限的光照条件下茁壮成长的知识在很大程度上缺乏。本研究将对介孔深度的光收集进行定量评估，并对生物光学和辐照度在珊瑚群落结构中的作用提供新的见解。为了实现我们的目标，我们将采用跨学科的方法来建立介孔珊瑚的生物光学特性。我们的工作流程结合了(1)在埃拉特（以色列红海）的珊瑚礁实地调查，沿着深度-辐照度梯度收集和分析珊瑚，(2)基于实验室的光微传感器测量，结合内源性绿色荧光蛋白分析和光合作用分析；(3)光学相干断层扫描和微计算机断层扫描，用于表征组织和骨骼形态，用于开发使用蒙特卡罗模拟的3D光捕获模型；(3)一种新的生物3D打印方法，用于实验确定珊瑚骨架形态对光合作用的作用。总而言之，本研究将为寻求了解中叶珊瑚礁生态系统空间分布和预测其对环境变化的响应的理论模型提供必要的基础，从而为珊瑚礁管理和保护提供实用的工具。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。

Tropical coral reefs are hotspots of biodiversity and provide critical services to numerous coastal communities worldwide. A combination of global and local stressors have led to the unprecedented degradation of shallow water coral reef communities. Most importantly, elevated water temperatures combined with excess solar radiation can cause coral bleaching, which describes the loss of the coral’s symbiotic algae and is regarded as the major threat to the future existence of shallow-water reefs. Thus, corals from deep waters are gaining interest as they are expected to be buffered from extreme environmental impacts more commonly experienced in shallow waters. Surprisingly, corals are flourishing in habitats where sunlight barely reaches, and 30-150 m depth mesophotic coral reef ecosystems (MCEs) are characterized by unique coral communities that could serve as a refuge for shallow water corals. In this project, we aim to study the light-harvesting mechanisms that allow corals to thrive under such light-limited conditions using a multidisciplinary approach that combines state-of-the-art bioengineering, bio-optics, and coral physiology tools. Since corals are among the most efficient aquatic photosynthetic systems, studying coral bio-optics can also lead to the discovery of novel light-harvesting mechanisms and the development of novel coral-inspired photonic materials to build more efficient and sustainable photobioreactors. This is a US-Israel binational project that aims to promote international collaboration and diversity through a range of public outreach activities, including museum exhibitions and the design of creative experiences to support the participation of under-represented groups in STEM.Light is a key driver of coral community change along the coral reef depth gradient. However, the importance of irradiance for the existence and growth of corals has been predominantly studied in shallow species, and knowledge of how mesophotic corals thrive despite extremely limited light conditions is largely lacking. This study will provide a quantitative assessment of light-harvesting at mesophotic depths and offer novel insights into the role of bio-optics and irradiance in structuring coral communities. To achieve our goal, we will employ an interdisciplinary approach to establish the bio-optical properties of mesophotic corals. Our workflow combines (1) in-situ coral reef fieldwork in Eilat (Red Sea, Israel) to collect and analyze corals along a depth-irradiance gradient, (2) lab-based light microsensor measurements combined with analyses of endogenous green fluorescent protein and photosynthetic assays; (3) optical coherence tomography and microcomputed tomography to characterize tissue and skeletal morphology for the development of 3D light-capture models using Monte Carlo simulations; and (3) a novel 3D bioprinting approach to experimentally determine the roles of coral skeleton morphology on photosynthesis. Altogether, this research will provide the essential basis for theoretical models that seek to understand the spatial distribution of mesophotic coral reef ecosystems and predict their responses to environmental change, therefore offering a practical tool for reef management and conservation.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.