Ocean Acidification: Effects on Morphology and Mineralogy in Otoliths of Larval Reef Fish

如果一条幼鱼不能避开捕食者，不能在三维空间中定位自己，对个体和种群的影响是巨大的。耳石（耳石），从富含碳酸氢盐和碱性pH值的流体中沉淀碳酸钙形成，对鱼类的运动和定向至关重要。虽然海洋鱼类补偿周围沃茨中的二氧化碳水平，但人们对溶解的二氧化碳增加和碳酸氢盐浓度的变化如何影响耳石的形成知之甚少。大气中二氧化碳浓度增加，导致海洋pH值下降（海洋酸化），可能会对这些关键结构的沉积、生长和功能产生深远影响，特别是对幼鱼。专注于前结算年龄的幼体礁鱼（Amphiprion clarkii和Chrysiptera parasema），这项研究整合了碳酸盐矿物学，耳石发育和礁鱼生物学的专业知识，并利用这种独特的专业知识组合来回答有关海洋酸化对耳石结构和功能的影响的基本问题。具体来说，这项研究将回答两个基本问题：在生长的耳石中，自然形态和矿物学的变化是什么？当幼虫暴露在高浓度的溶解二氧化碳中时，这些变化是如何发生的？将在高二氧化碳诱导的低pH值下孵化和饲养幼虫，并在实验期间提取三种类型的耳石（箭石、火山石、石砾）。碳酸钙矿物学从文石（最常见）到球文石（不太常见，密度较低）的变化以及晶体习性的变化（形成良好到形成不良）将使用显微镜和形态测定技术的组合进行评价。在理解耳石形态学和矿物学方面的差距排除了我们准确评估海洋酸化对幼鱼生存的影响的能力。鉴于我们知道很少的形态学和矿物学的所有三种耳石类型的幼虫海洋鱼类，这项研究将提供有关自然变异的基础数据。未暴露和暴露的幼虫的数据将告知我们的耳石和结构功能关系的发展的理解。此外，耳石提供了长期的环境生活史的记录，可以更好地利用，如果我们了解环境条件和耳石形态和矿物学之间的关系。这项研究代表了马萨诸塞州波士顿大学（少数民族服务机构），新英格兰水族馆（NEAq;非营利研究水族馆）的教师和学生之间独特的跨学科合作，并通过与NEAq，罗杰威廉姆斯大学（主要是本科院校）的正式合作伙伴关系。NEAq是波士顿最重要的旅游景点之一，每年有超过130万游客，也是主要的公共教育资源。除了重要的研究成果，该项目还支持非正式科学教育材料的开发，这些材料将分发给公众，并在NEAq Harborside学习实验室和NEAq海洋中心展出。该项目还支持培养1名博士生和1名本科生。

If a larval fish cannot avoid predators and cannot orient itself in three-dimensional space, the consequences to the individual and the population are dramatic. Otoliths (ear stones), formed precipitation of calcium carbonate from a bicarbonate-rich and alkaline pH fluid, are critical to fish movement and orientation. Although marine fish compensate for carbon dioxide levels in the surrounding waters little is known about how increased dissolved carbon dioxide and changes in bicarbonate concentrations will impact the formation of otoliths. Increasing atmospheric carbon dioxide concentrations, leading to decreased ocean pH (ocean acidification) may have profound impact on the deposition, growth and function of these critical structures, particularly in larval fish. Focusing on pre-settlement age larval reef fish (Amphiprion clarkii and Chrysiptera parasema), this research integrates expertise in carbonate mineralogy, otolith development, and reef fish biology and leverages this unique combination of expertise to answer fundamental questions regarding the impact of ocean acidification on the structure and function of otoliths. Specifically, the research will answer two fundamental questions: What are the natural morphological and mineralogical variations within growing otoliths? How do these change when larvae are exposed to high dissolved carbon dioxide concentrations? Larvae will be hatched and reared under high carbon dioxide-induced low pH and three types of otoliths (sagittae, lapilli, asterisci) will be extracted over the duration of the experiments. Changes in calcium carbonate mineralogy from aragonite (most common) to vaterite (less common, less dense) as well as changes in crystal habit (well formed to poorly formed) will be evaluated using a combination of microscopic and morphometric techniques. The gap in understanding of otolith morphology and mineralogy precludes our ability to accurately evaluate the impact of ocean acidification on larval fish survival. Given that we know very little about the morphology and mineralogy of all three otolith types in larval marine fish, this research will provide fundamental data regarding natural variability. Data from unexposed and exposed larvae will inform our understanding of the development of otoliths and structure-function relationships. Additionally, otoliths provide long-term records of environmental life histories that could be better exploited if we understood the relation between environmental conditions and otolith morphology and mineralogy. This research represents a unique interdisciplinary collaboration between faculty and students at the University of Massachusetts Boston (a minority-serving institution), New England Aquarium (NEAq; not-for-profit research aquarium), and, through a formal partnership with NEAq, Roger Williams University (primarily undergraduate institution). NEAq is one of the premier visitor attractions in Boston, with over 1.3 million visitors a year, and a major public education resource. In addition to significant research outcomes this project also supports the development of informal science education materials that will be distributed to the public and displayed at the NEAq Harborside Learning Lab and NEAq Ocean Center. The project also supports the training of 1 PhD student and 1 undergraduate student.