BEACON: BErmuda ocean Acidification and COral reef iNvestigation

人为排放二氧化碳造成的海洋酸化是对珊瑚和珊瑚礁等海洋钙化生物和生态系统的重大和紧迫的威胁。作为未来海洋酸化的结果，即增加海水二氧化碳，降低pH、碳酸盐离子浓度[CO3]和碳酸盐饱和状态，海洋钙化物很可能难以以目前的速度生长其碳酸钙(CaCO3)的外壳和骨架。碳酸盐沉积物和结构的溶解也可能增加，最终可能超过钙化作用和CaCO3的产生，导致个别珊瑚群落、珊瑚群落和珊瑚礁生态系统的碳酸盐物质从净积累过渡到净损失。由于百慕大的纬度相对较高(32°N)，百慕大的年平均表层海水[CO3]低于靠近热带的地区。因此，由于持续的海洋酸化，百慕大珊瑚礁很可能在热带珊瑚礁之前经历临界[CO3]值和净溶解。此外，[CO3]的自然梯度沿百慕大珊瑚礁存在，环境参数，如光、温度和营养物质几乎相同。这种梯度允许对自然环境中不同[CO3]下的单个钙化物和钙化群落的钙化进行独特的交叉比较。在这项研究中，百慕大海洋科学研究所(BIOS)的研究人员将启动Beacon项目，以进一步了解海洋酸化对钙化和CaCO3生产过程的影响，在三个不同的空间尺度上，包括(1)单个珊瑚殖民地，(2)当地珊瑚礁群落，和(3)区域珊瑚礁生态系统。他们将开展(1)现场和体外实验，以评估百慕大和加勒比共同的三个不同物种在自然和受控实验条件下暴露于不同[CO3]环境下的个别珊瑚群落的生长和净钙化情况；(2)Diel和准拉格朗日钙化实验，以评估当地珊瑚礁群落以及百慕大平台沿自然[CO3]梯度移动的水团的净钙化情况；(3)跨百慕大平台和近海收集的时间序列数据，以评估百慕大珊瑚礁生态系统和平台在季节性和年度循环中的净钙化和CaCO3的产生。更广泛的影响：该项目将在不同的时间和空间尺度上提供有关海洋酸化对珊瑚礁的影响的基本数据。综合起来，每个尺度上的知识将有助于在更广泛的背景下更好地理解这一问题，即在过去、现在和未来的海水化学条件下，作为一个全球实体对珊瑚礁的影响和在全球碳循环中的作用。顾名思义，研究小组设想灯塔将作为指导灯，帮助研究人员和政策制定者制定未来战略，并就珊瑚礁管理和二氧化碳排放政策做出决定，以建立二氧化碳稳定目标。该项目的科学理解和研究产品将专门用于基本输入输出系统探索者计划、COE POGO海洋酸化模块和在基本输入输出系统教授的珊瑚礁生态课程。它还将有助于培养基本输入输出系统的一名研究生和一名研究技术员的研究和技术技能，并将包括每年该项目的实习生和国家科学基金会REU奖学金学生的参与。

Ocean acidification owing to anthropogenic emission of CO2 is a significant and imminent threat to marine calcifying organisms and ecosystems such as corals and coral reefs. As a result of future ocean acidification, i.e., increasing seawater CO2, and decreasing pH, carbonate ion concentration [CO3], and carbonate saturation state, it is likely that marine calcifiers will have difficulty growing their shells and skeletons of calcium carbonate (CaCO3) at their present rates. Dissolution of carbonate sediments and structures are also likely to increase, and could ultimately exceed calcification and CaCO3 production, leading to a transition from net accumulation to a net loss in carbonate material of individual coral colonies, coral communities and coral reef ecosystems. Because of Bermuda's relatively high-latitude location (32° N), the annual average surface seawater [CO3] is lower in Bermuda than regions closer to the tropics. As a consequence, the Bermuda coral reef is likely to experience critical [CO3] values and net dissolution before its tropical counterparts as a result of continued ocean acidification. Furthermore, a natural gradient in [CO3] exists along the Bermuda reef with environmental parameters such as, light, temperature, and nutrients being near identical. This gradient allows for unique cross-comparisons of calcification of individual calcifiers and calcifying communities under different [CO3] in a natural environment. In this study, researchers at the Bermuda Institute of Ocean Science (BIOS) will launch the BEACON project to further our understanding of the consequences of ocean acidification to the process of calcification and CaCO3 production at three different spatial scales including (1) individual coral colonies, (2) local reef communities, and (3) regional coral reef ecosystems. They will conduct (1) in situ and in vitro experiments to assess growth and evaluate net calcification of individual coral colonies of three different species common to Bermuda and the Caribbean exposed to different [CO3] under both natural and controlled experimental conditions; (2) diel and quasi-lagrangian calcification experiments to evaluate net calcification of local reef communities and in moving water masses along the natural [CO3] gradient existent on the Bermuda platform; and (3) time series data collected across the Bermuda platform and offshore, to evaluate net calcification and CaCO3 production of the Bermuda coral reef ecosystem and platform over seasonal and annual cycles. Broader impacts : This project will provide fundamental data on the consequences of ocean acidification to coral reefs on different temporal and spatial scales. Combined, knowledge at each of the scales will contribute to an improved understanding of this problem in a broader context, i.e., the effect on coral reefs as a global entity and role in the global carbon cycle during past, present and future seawater chemical conditions. As the meaning implies, the research team envisions BEACON to serve as a guiding light to assist researchers and policymakers in framing future strategies and making decisions regarding the management of coral reefs and CO2 emission policies in order to establish CO2 stabilization targets. Scientific understanding and research products from the project will be specifically used in the BIOS explorer program, CoE POGO ocean acidification module, and the coral reef ecology class taught at BIOS. It will also contribute to developing the research and technical skills of one graduate student and one research technician at BIOS, and will include the involvement of interns and NSF REU fellowship students each year of the project.