Ocean Acidification: Collaborative Research: Quantifying the potential for biogeochemical feedbacks to create 'refugia' from ocean acidification on tropical coral reefs

海洋表面温度上升和海洋酸化可能会威胁钙化生物建造碳酸盐珊瑚礁的能力，但尚不清楚特定珊瑚礁是否有能力承受全球变化。目前对OA对珊瑚礁影响的了解源于单一物种的实验室研究，主要集中在硬珊瑚上。传统上，这些实验试图在假设沿海地区与开放的海洋表面水域一样恒定--并将以同样的速度酸化--的假设下，模拟未来的静态条件。基于这些过于简化的情景的预测是不切实际的，因为包括钙化生物和初级生产者在内的许多底栖生物在一天的循环中显著改变了大量海水碳酸盐的化学组成。此外，最近在一些珊瑚礁上普遍存在的海底pH极端波动表明，底栖物种可能已经适应了未来的碳酸盐条件。为了在珊瑚礁上寻找潜在的避难所，斯克里普斯海洋研究所(加州大学圣地亚哥分校)和拉蒙特·多尔蒂地球天文台(哥伦比亚大学)的一个研究小组将对中太平洋的一个偏远的无人居住的岛屿巴尔米拉环礁进行一项独特的机械研究，该岛屿没有受到当地人类影响的退化。他们将探索珊瑚礁底栖群落对上述海水化学的生物地球化学反馈的强度和控制，并通过实验确定这种自然波动如何影响关键类群对OA的生理反应。具体地说，它们将：(1)将一项新的原位海底通量技术与正在进行的高空间分辨率海底群落动力学研究紧密结合起来，这项技术能够对净生态系统代谢率(生产和钙化)进行连续、高时间分辨率的测量，以量化已知物种组合对所观察到的海水碳酸盐化学自然时空变异性的反馈；以及(2)利用实验室中的小规模共同花园二氧化碳增加实验和生产力/呼吸分析，并结合现场相互移植实验，对二氧化碳升高和/或波动对共同框架建筑生物体及其海底竞争对手的生长、钙化和光生理学的影响进行经验量化。这将使他们能够在没有其他令人困惑的人类影响的情况下，在其自然环境中审查海洋生态系统与不同的海底珊瑚礁生物之间的相互作用。更广泛的影响。海洋酸化预计将影响人类社会已经开始依赖的一些生态系统商品和服务。具体地说，珊瑚礁提供的防止海岸侵蚀的物质保护将减少，可能会加剧海平面上升的影响，而海洋酸化对渔业和旅游业的影响尚不确定。一个核心目标是与当地社区和组织合作，更好地教育公众了解开放式获取将如何影响人、社会及其使用的自然资源，并为个人提供工具，使他们能够成为解决方案的一部分。为此，研究小组与圣地亚哥当地非营利性公共广播服务机构KPBS建立了强有力的伙伴关系，以开发开放式获取通信和教育的新产品。此外，他们将与SIO的桦树水族馆合作，开发一个交流项目结果的展览。最后，该项目将直接培训实习生、学生和研究人员，并将通过各种外联活动促进多样性，包括公开讲座、培训水族馆讲解员和开发基于网络的教材。

Rising sea surface temperatures and ocean acidification (OA) may threaten the ability of calcified organisms to build carbonate reefs, but it is unclear if particular reefs have the capacity to tolerate global change. Current understanding of the effects of OA on coral reefs originates from single-species laboratory studies largely focused on scleractinian corals. Traditionally, these experiments attempt to mimic static future conditions under the assumption that coastal regimes are as constant as -- and will acidify at the same rate as -- open ocean surface waters. Predictions based on these oversimplified scenarios are unrealistic because numerous benthic organisms, including calcifiers and primary producers, significantly alter the bulk seawater carbonate chemistry over a diurnal cycle. Further, the prevalence of recently appreciated extreme diel fluctuations in pH across some reefs suggests that benthic species may be acclimated to future carbonate conditions. To look for potential OA refugia on reefs, a research team from the Scripps Institute of Oceanography (University of California at San Diego) and the Lamont Dougherty Earth Observatory (Columbia University) will undertake a unique mechanistic study on Palmyra Atoll, a remote uninhabited island in the central Pacific that lacks degradation from local human influence. They will explore the strengths and controls of biogeochemical feedbacks from coral reef benthic community assemblages to the seawater chemistry above and experimentally determine how this natural fluctuation affects physiological responses of key taxa to OA. Specifically they will: (1) tightly integrate a novel benthic flux technique in situ that allows continuous, high-temporal resolution measurements of net ecosystem metabolic rates (production and calcification) with an ongoing high spatial resolution benthic community dynamics study to quantify feedbacks of known species assemblages to observed natural spatiotemporal variability in seawater carbonate chemistry; and (2) use small scale common garden CO2 enrichment experiments and productivity/respiration assays in the lab paired with reciprocal transplant experiments in situ to empirically quantify the effects of elevated and/or fluctuating pCO2 on growth, calcification and photophysiology of common framework building organisms and their benthic competitors. This should allow them to examine the coupled interactions between OA and diverse benthic coral reef organisms in their natural environment in the absence of other confounding human impacts. BROADER IMPACTS. Ocean acidification is expected to affect a number of ecosystem goods and services that human societies have come to depend on. Specifically, the physical protection that coral reefs provide from coastal erosion will be reduced, potentially exacerbating the effects of sea level rise, and the effects of OA on fisheries and tourism are yet to be determined. One central goal is to work with local communities and organizations to better educate the public about how OA will affect people, societies and the natural resources they use and to give individuals tools that can allow them to be part of the solution. To that end, the research team has established strong partnerships with a local non-profit public broadcasting service KPBS, San Diego to develop novel products for OA communication and education. Further, they will work with the Birch Aquarium at SIO to develop an exhibit that communicates the results of the project. Finally, the project will directly train interns, students and researchers and will promote diversity through a variety of outreach activities including public lectures, training of aquarium docents and the development of web-based educational materials.