Collaborative Research: Defying Dissolution: Unraveling the Enigma of North Pacific Deep-Sea Scleractinian Reefs in Undersaturated Water

就像浅水珊瑚一样，深海珊瑚为各种无脊椎动物和商业上重要的鱼类提供了结构和栖息地。然而，由于海洋酸化影响了表层和深海的水化学，深海珊瑚礁的未来是高度不确定的，因为海洋酸化使珊瑚更难以建立这些生态系统所依赖的三维结构。北太平洋天然恶劣的水化学条件正因海洋酸化而加剧，因此以前人们认为该地区不可能出现深海珊瑚礁的发育。尽管有这些期望，但最近在西北夏威夷群岛（NWHI）和皇帝海山链（ESC）发现了珊瑚礁，其中7个地点中的4个位于对构成深海珊瑚礁的珊瑚骨架具有腐蚀性或可能溶解的水域。随着这些珊瑚礁的发现，我们有了一个前所未有的机会来调查海洋酸化对这些重要生态系统的潜在影响，因为与之前的研究相反，在我们的研究地点，在相同的深度，有一个水化学的梯度。这项研究将解决有关深海珊瑚礁发育的基本问题，包括：深海珊瑚礁能否在对珊瑚骨骼有腐蚀性的水中发育？在有利的水化学条件下形成的珊瑚礁一旦经历了腐蚀性的水，它们的命运会怎样？珊瑚礁在腐蚀性的水中能坚持多久？通过解决这些问题，本研究将为深海珊瑚礁的形成、持久性、分布以及海洋酸化对深海珊瑚群落的影响提供关键的见解。调查人员和NOAA有合作记录吗？美国的深海珊瑚研究和技术计划，并与包括北太平洋渔业委员会和国际海底管理局在内的积极在该地区为海底山深海珊瑚群落做出管理决策的机构合作。研究结果将通过出版物、向博物馆提供的珊瑚收藏和公共数据库广泛分发给科学界。该项目将通过培训一名代表性不足的博士后科学家、三名研究生和本科生研究人员，促进发展一支多元化和有竞争力的STEM劳动力队伍。与WhaleTimes公司的合作将包括潜入深海项目的ROV远程呈现、K-12学校访问和电子书。尽管人们认为在北太平洋恶劣的碳酸盐化学条件下不可能存在深海硬石质珊瑚礁，但最近在西北夏威夷群岛（NWHI）和皇帝海山链（ESC）中发现了珊瑚礁，其中7个地点中有4个处于文石不饱和的水域。这些珊瑚礁的发现，超过一半的地点在不饱和的水域，为研究海洋酸化对这些重要生态系统的潜在影响提供了前所未有的机会。由于文石饱和层（ASH）在全球海洋酸化的影响下逐渐变浅，因此更好地了解文石饱和度在深海硬核礁分布中的作用变得至关重要。在不久的将来，随着文石饱和度的下降和ASH的浅滩，更多的深海珊瑚礁将经历欠饱和，这使得深海珊瑚礁及其所支持的具有生态和经济价值的生态系统的未来高度不确定。基于在西北海洋保护区和ESC发现的深海珊瑚礁，本项目的首要问题是：虽然个别珊瑚可能在不饱和的海水中钙化，但由于深海钙化速度缓慢，而且大多数珊瑚礁基质是易溶解的死骨架，因此不太可能形成三维的珊瑚礁结构。因此，需要验证的假设是：1)这些深海珊瑚礁在饱和水域发育，现在处于欠饱和水域，因为ASH已经浅滩；2)欠饱和水域的珊瑚礁正处于净溶解状态；3)除文石饱和度外，其他环境参数也影响着珊瑚礁的分布。为了验证这三个假设，我们计划了两次研究巡航，以表征横跨文石饱和度梯度的九个海山的珊瑚礁和环境参数，其中珊瑚礁存在于ASH上方和下方。将收集珊瑚和水样，ROV将进行视频样带调查，并在珊瑚礁地点部署实验溶解块和原位仪器，以调查：在diel（原位仪器）到百年（骨骼硼同位素作为pH值代表）尺度上的碳酸盐化学变化，钙化和溶解速率以及珊瑚礁生态。此外，物种分布模型将用于检查决定这些深海珊瑚礁分布的环境因素。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。

Like their shallow-water counterparts, deep-sea corals provide structure and habitat that support a diverse community of invertebrates and commercially important fish species. However, as ocean acidification impacts the water chemistry of the surface and deep ocean, the future of deep-sea reefs is highly uncertain because ocean acidification makes it more difficult for corals to build the three-dimensional structure that these ecosystems depend on. The naturally harsh water chemistry conditions of the North Pacific are being exacerbated by ocean acidification therefore it was previously thought that deep-sea coral reef development could not occur in the region. Despite these expectations, reefs were recently discovered in the Northwestern Hawaiian Islands (NWHI) and the Emperor Seamount Chain (ESC), with 4 of 7 sites in waters that are corrosive to, or likely to dissolve, the coral skeletons that make up deep-sea reefs. With the discovery of these reefs, we have an unprecedented opportunity to investigate the potential impact of ocean acidification on these important ecosystems because, in contrast to previous studies, there is a gradient of water chemistry across our study sites, all at the same depth. This study will address basic questions regarding reef development in the deep sea, including: Can deep-sea coral reefs develop in water that is corrosive to coral skeletons? What is the fate of reefs that developed under supportive water chemistry conditions once they experience corrosive water? How long can reefs persist in corrosive water? Through addressing these questions, this study will provide critical insights into deep-sea reef formation, persistence, distribution, and the effects of ocean acidification on deep-sea coral communities. The investigators have a track record of partnerships with NOAA?s Deep-Sea Coral Research and Technology Program, and with the agencies actively making management decisions in this region for seamount deep-sea coral communities including the North Pacific Fisheries Commission and the International Seabed Authority. Results will be broadly circulated to the scientific community through publications, coral collections contributed to museums, and public databases. This project will contribute to developing a diverse and competitive STEM workforce through training of an underrepresented postdoctoral scientist, three graduate students, and undergraduate researchers. A partnership with WhaleTimes, Inc. will include ROV telepresence for the Creep into the Deep Program, K-12 School Visits, and e-books. Despite expectations that deep-sea scleractinian reefs could not exist under the harsh carbonate chemistry conditions of the North Pacific, reefs were recently discovered in the Northwestern Hawaiian Islands (NWHI) and the Emperor Seamount Chain (ESC), with 4 of 7 sites in waters undersaturated with respect to aragonite. The discovery of these reefs, with more than half the sites in undersaturated water, provides an unprecedented opportunity to investigate the potential impact of ocean acidification on these important ecosystems. It is becoming critical to gain a better understanding of the role of aragonite saturation in the distribution of deep-sea scleractinian reefs because it has been documented that the aragonite saturation horizon (ASH) is shoaling throughout the world oceans due to ocean acidification. More deep-sea reefs will experience undersaturation in the near future as aragonite saturation declines and the ASH shoals, making the future of deep-sea reefs and the ecologically and economically valuable ecosystems they support highly uncertain. Building on the discovery of deep-sea coral reefs in the NWHI and ESC, the overarching question of this project is: How is it that deep-sea scleractinian coral reefs can occur in undersaturated water, well below the hypothesized reef development limit Although individual corals may be capable of calcifying in undersaturated water, it is unlikely that a three-dimensional reef structure could develop since deep-sea calcification rates are slow and most of the reef matrix is dead skeleton susceptible to dissolution. Therefore the hypotheses to be tested are: 1) These deep-sea reefs developed in saturated water and are now in undersaturated water because the ASH has shoaled; 2) The reefs in undersaturated water are now net dissolving; and 3) Environmental parameters other than aragonite saturation are driving reef distribution. To test these three hypotheses, we plan two research cruises to characterize the reefs and environmental parameters of nine seamounts across an aragonite saturation gradient where reefs exist above and below the ASH. Coral and water samples will be collected, an ROV will conduct video transect surveys, and experimental dissolution blocks and in situ instrumentation will be deployed at the reef sites to investigate: carbonate chemistry variability on diel (in situ instruments) to centennial (skeletal boron isotopes as a pH proxy) scales, calcification and dissolution rates, and reef ecology. Further, species distribution modeling will be used to examine the environmental factors that determine the distribution of these deep-sea reefs.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.