Collaborative Research: Ocean Acidification: RUI: Multiple Stressor Effects of Ocean Acidification and Hypoxia on Behavior, Physiology, and Gene Expression of Temperate Reef Fishes

对于居住在加州海流等上升流生态系统的近岸海洋物种来说，人为向大气中排放二氧化碳所引起的气候变化可能会导致海洋酸化和缺氧的并行条件，在季节性上升流期间，这种情况会加剧。尽管海洋鱼类由于具有酸碱调节能力而被普遍推定为对OA具有耐受性，但最近在热带地区的研究表明，早期生命阶段可能通过损害呼吸、酸碱调节和神经递质功能而对溶解CO2水平的升高特别敏感(这会降低海水的pH)。低水平的溶解氧(DO)在低氧时发生，同样会影响海洋鱼类的行为、生理和生存。很少有研究涉及低pH、低DO环境的潜在交互影响。从分子工具到整个动物生理学，这项研究将深入检查一个内在的整合过程。这项研究将使用多应激源框架来解决OA和低氧对温带珊瑚鱼的行为、生理能力和基因表达的独立和综合影响所构成的潜在威胁。由于早期生命阶段的死亡率具有重要的遗留效应，因此了解这些应激源的影响对于预测未来全球鱼类种群的气候变化反应至关重要。这些信息将为进一步研究多种应激源的协同效应和加州当前物种的特征奠定基础，这些特征影响它们在快速变化的气候中容忍或适应海洋化学变化的能力。该项目的更广泛影响包括为4所院校的研究生和本科生提供教育机会，以及通过教学强化方案为K-12学生和教师开展外联和教育活动。结果将被传达给渔业管理机构、海洋观测方案和科学界，以提供关于气候变化对具有经济价值的底层鱼类的影响的信息。该项目的目标是利用实验室和实地研究相结合的方式，检查岩鱼幼体对海洋酸化和低氧的独立和交互影响的生态和生理相关的反应。岩鱼将在野外捕获，然后在实验室中以4种不同的二氧化碳水平和4种不同的DO水平饲养，以模拟环境条件的变化。响应变量包括：(1)测量嗅觉能力、大脑功能不对称和解决问题的能力的变化，以及(2)对游泳能力、呼吸、有氧运动和生长的影响。此外，我们将使用下一代转录组测序来检测全基因组Na/K ATPase(NKA)、柠檬酸合成酶(CS)和乳酸脱氢酶(LDH)的基因表达和酶活性的变化，作为酸碱补偿和有氧代谢和无氧代谢之间代谢转换的代用品。将在实地部署海洋传感器，以确定加利福尼亚州北部和中部近岸栖息地发生缺氧和低pH事件的频率和强度。对岩鱼幼鱼的适应性采样将被用来评估在现场暴露于低pH和低DO事件的个体的基因表达和生理反应。我们将比较不同生活史(如幼体持续时间、产卵时间等)的岩鱼物种对OA和缺氧的影响。并从暴露于低pH/低DO事件的不同地区收集，以应对局部适应的可能性。该项目的重点是定居时早期幼体阶段的反应，因为这一阶段在关键时期暴露于近岸海洋化学的变化，在这一时期，由于捕食风险增加，生理应激和行为中断可能具有最强烈的人口统计学影响。

For near shore marine species inhabiting upwelling ecosystems such as the California Current, climate change resulting from the anthropogenic release of CO2 into the atmosphere is likely to induce concurrent conditions of ocean acidification (OA) and hypoxia, which are exacerbated during periods of seasonal upwelling. Although marine fishes have generally been presumed to be tolerant of OA due to their competence in acid-base regulation, recent studies in tropical regions suggest that early life stages may be particularly sensitive to elevated levels of dissolved CO2 (which lowers seawater pH) by impairing respiration, acid-base regulation, and neurotransmitter function. Low levels of dissolved oxygen (DO), which occur during hypoxia, can likewise impact the behavior, physiology and survival of marine fishes. Few studies have addressed the potential interactive effects of a low pH, low DO environment. From molecular tools to whole animal physiology, this research will provide an in-depth examination of an inherently integrative process. The study will use a multiple stressor framework to address the potential threats posed by the independent and combined effects of OA and hypoxia on behavior, physiological capacity, and gene expression in temperate reef fishes. Because mortality in early life stages has important carryover effects, understanding the effects of these stressors is critical for predicting future climate change responses of global fish populations. Such information will lay the groundwork for further studies that address the synergistic effects of multiple stressors and the characteristics of California Current species that influence their ability to tolerate or adapt to changes in ocean chemistry in a rapidly changing climate. Broader impacts of the project include educational opportunities for graduate and undergraduate students at 4 institutions and outreach and educational activities for K-12 students and teachers through the Teaching Enhancement Program. Results will be communicated to fisheries management agencies, oceanographic observing programs, and the science community to provide information on climate change impacts for economically valuable groundfish.The project goals are to use a combination of laboratory and field studies to examine ecologically and physiologically relevant responses of juvenile rockfish (genus Sebastes) to the independent and interactive effects of ocean acidification and hypoxia. Rockfish will be captured in the field and then reared in the lab at 4 different pCO2 levels and 4 different DO levels to simulate changes in environmental conditions. Response variables include: (1) measures of changes in olfactory capabilities, brain functional asymmetry and problem-solving ability and (2) effects on swimming capabilities, respiration, aerobic performance, and growth. In addition, we will use next generation transcriptome sequencing to examine genome-wide changes in gene expression and enzyme activity for Na+/K+ ATPase (NKA), citrate synthase (CS), and lactate dehydrogenase (LDH), as proxies for acid-base compensation and metabolic shifts between aerobic and anaerobic metabolism. Oceanographic sensors will be deployed in the field to determine the frequency and intensity of hypoxia and low pH events in near shore habitats in Northern and Central California. Adaptive sampling of juvenile rockfish will be used to evaluate gene expression and physiological responses in individuals exposed in situ to low pH and low DO events in the field. The effects of OA and hypoxia will be compared across rockfish species with different life histories (e.g. larval duration, timing of spawning, etc.) and collected from regions differing in exposure to low pH/low DO events to address the potential for local adaptation. The focus of this project is on responses of the early juvenile stage at the time of settlement, because this stage is exposed to near shore changes in ocean chemistry during a critical period where physiological stress and behavioral disruptions may have the strongest demographic effects due to increased risk of predation.