Carbon Cycling in Carbonate-Dominated Benthic Ecosystems: Eddy Covariance Hydrogen Ion and Oxygen Fluxes

海底之内和之上发生的化学和生物过程可造成元素与海水的化学交换，并对浅水沿海系统的碳和营养物循环作出重大贡献。然而，这些过程极难在海洋中直接测量，目前还没有令人满意的方法来量化其全部影响。承担该项目的研究人员开发了一种独特的现场仪器，称为涡流协方差H+和O2交换系统（ECHOES）。这些对海底和上覆海水之间的氢离子（H+）和氧（O2）交换的新测量将允许对重要的生物和化学反应进行独特的直接评估。来自ECHOES的数据将改变对海底过程对经历海水化学快速变化的沿海生态系统恢复力的潜在关键贡献的理解。该项目的成果将为改进沿海酸化后果模型提供关键数据。 此外，本发明还该项目将通过伍兹霍尔海洋研究所的暑期学生奖学金计划资助一名早期职业科学家和指导海洋科学研究的本科生。实验室实验已经成功地研究了单个生物的底栖反应和与海水化学变化有关的化学反应，但由于对所需的一套地球化学通量进行现场测量的方法不令人满意。在百慕大以碳酸盐为主的各种海底站点部署ECHOES是同时测量净群落生产（NCP）和净群落钙化（NCC）的开创性努力。这项研究将侧重于传统上难以研究的系统，包括复杂的珊瑚礁，垂直海草冠层，裸露的渗透性沉积物，评估昼夜变化，斑块，上游通量对下游生态系统的影响。重要的地球化学参数（如pH、CO2、O2、碱度等）由于大气中二氧化碳含量的增加，在这些多产的浅水环境中，大气中二氧化碳含量的日波动幅度可能比100年模型预测的开阔海洋的动态范围更大。因此，这项研究产生的新的现场数据将有助于确定潜在的关键和迄今为止不明确的作用，浅，生产性碳酸盐沉积物的生态系统对海洋酸化的响应的预测模型。

Chemical and biological processes that occur in and on the seafloor can create chemical exchange of elements with seawater and make significant contributions to carbon and nutrient cycling in shallow coastal systems. However, these processes are exceedingly difficult to measure directly in the ocean, with no satisfactory methods currently available to quantify their full impact. The researchers undertaking this project have developed a unique, field instrument referred to as the Eddy Covariance H+ and O2 Exchange System (ECHOES). These novel measurements of hydrogen ion (H+) and oxygen (O2) exchange between the seafloor and the overlying seawater will allow unique, direct evaluation of the important linked biological and chemical reactions. Data from ECHOES will transform understanding of the potentially critical contribution of seafloor processes to the resilience of coastal ecosystems experiencing rapid changes in seawater chemistry. Results from this project will provide critical data for improved models of the consequences of coastal acidification. Additionally, this project will fund an early career scientist and the mentorship of undergraduate students in ocean science research through the Woods Hole Oceanographic Institute's Summer Student Fellowship Program.Laboratory experiments have successfully examined the benthic response of individual organisms and chemical reactions to stress related to changing seawater chemistry but the integrated response of intact ecosystems has been very difficult to quantify due to unsatisfactory methods for in situ measurements of the required suite of biogeochemical fluxes. This deployment of ECHOES at a variety of carbonate-dominated seafloor sites in Bermuda is a pioneering effort to simultaneously measure net community production (NCP) and net community calcification (NCC). The study will focus on traditionally difficult-to-study systems including complex reefs, vertical seagrass canopies, and bare permeable sediments, evaluating diel variability, patchiness, and the impact of upstream fluxes on downstream ecosystems. Important biogeochemical parameters (e.g. pH, CO2, O2, alkalinity, etc.) in these productive shallow environments can experience daily fluctuations over a greater dynamic range than 100-year model projections for the open ocean due to increasing atmospheric CO2. Therefore, the novel field data generated by this research will help define the potentially critical and heretofore ill-defined role for shallow, productive carbonate sediments in predictive models of ecosystem response to ocean acidification.