Respiratory Acclimation of Marine Fish to Ocean Deoxygenation

包括气候变化在内的人为因素正在增加世界各地海洋中的低氧区(即海洋除氧)，在墨西哥湾北部尤其如此，那里经常出现大的季节性最低含氧区。沿海水域的除氧对海洋生物有严重影响，包括这些区域特有的经济和生态上重要的鱼类物种。人们假设，遭受这种环境变化的物种的长期生存部分取决于它们通过改变生理来适应的能力，这一概念被称为表型可塑性。这项建议将结合分子生物学、生物化学和全动物生理学来探索经济上重要的鱼种--红鱼在长期暴露于氧气供应不足的情况下，提高呼吸摄氧量的能力。这项工作的成果将纳入针对K-12学生的公共教育倡议。这些努力的目标将是提高青年和公众的科学素养，重点是了解海洋健康、气候变化的核心原则，以及健康海洋和鱼类种群对沿海社区的重要性。此外，还将为几名本科生和研究生以及一名博士后提供综合生理学方面的指导研究培训。本工作的主要目的是探讨具有代表性的海水鱼类红鱼在长期低氧环境中呼吸可塑性的生理机制和生态学意义。这些暴露将发生在物种的临界氧气阈值以上，并将评估红鼓最大限度地扩大有氧范围的能力，这将增加生态上重要活动的能力。这项工作整合了多个层次的组织，首先利用基因表达和生物化学来探索红细胞、心脏和红肌的可塑性，然后将测量整个动物的表现。该项目涉及与缺氧暴露有关的下列假说：1)鱼类将表现出与红细胞和血浆中可及碳水化合物酶水平一致的改变的血红蛋白表达模式，这将协同作用加强心脏和肌肉中的氧负荷；2)心脏和肌肉将显示出减少的线粒体质子泄漏，从而每单位氧气产生更多的能量；3)驯化将导致生物组织水平的游泳成绩和有氧能力提高；4)红鼓在生命的早期阶段暴露在低氧水平下将表现出刚性的表型可塑性，导致晚年生命的表型发生变化。这一综合评估将为海洋鱼类抵消海洋脱氧对呼吸性能的有害影响的能力提供宝贵的洞察力。这些活动还将有助于研究生和本科生以及博士后的培训，其成果将纳入公共教育举措，重点是气候变化和海洋除氧对海洋生物的影响。该奖项由海洋科学地球科学分部、生物海洋学计划和综合组织系统、生理机制和生物力学计划生物部共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Anthropogenic factors, including climate change, are increasing the prevalence of low-oxygen zones in oceans around the world (i.e., ocean deoxygenation), and this is especially true in the northern Gulf of Mexico where large seasonal oxygen minimum zones are common. Deoxygenation of coastal waters has serious implications for marine life, including the economically and ecologically important fish species endemic to these regions. It is hypothesized that the long-term survival of species subjected to this type of environmental change depend in part on their ability to acclimate by altering their physiology, a concept known as phenotypic plasticity. This proposal will use a combination of molecular biology, biochemistry, and whole-animal physiology to explore the ability of an economically important fish species, the red drum (Sciaenops ocellatus), to enhance respiratory oxygen uptake following exposure to prolonged periods of reduced oxygen availability. Results of this work will be incorporated into public education initiatives targeting K-12 students. The goal of these efforts will be to increase the scientific literacy of youth and the general public with an emphasis on understanding the core principles of ocean health, climate change, and the importance of healthy oceans and fish populations for coastal communities. In addition, mentored research training in integrative physiology will be provided for several undergraduate and graduate students and a post-doctoral fellow. The primary objective of this work is to explore the physiological mechanisms and ecological significance of respiratory plasticity in a representative marine fish, the red drum, exposed to prolonged environmental hypoxia. These exposures will occur above the critical oxygen threshold for the species, and the capacity of red drum to maximize aerobic scope, which would increase the capacity for ecologically important activities, will be assessed. This work integrates across multiple levels of organization by first exploring plasticity in the red blood cells, heart and red muscle using gene expression and biochemistry, after which whole-animal performance will be measured. The project addresses the following hypotheses related to hypoxia exposure: 1) fish will exhibit an altered pattern of hemoglobin expression coincident with elevated red blood cell and plasma accessible carbonic anhydrase that will work cooperatively to enhance oxygen offloading in the heart and muscle; 2) the heart and muscle will exhibit reduced mitochondrial proton leak, thereby generating more energy per unit oxygen; 3) acclimation will result in increased swimming performance and aerobic scope at the organismal level; 4) red drum exposed to reduced oxygen levels at early life stages will exhibit rigid phenotypic plasticity that results in altered phenotypes later in life. This comprehensive evaluation will provide invaluable insight into the ability of marine fishes to offset the deleterious effects of ocean deoxygenation on respiratory performance. These activities will also contribute to graduate and undergraduate student and post-doctoral training, and results will be integrated into public education initiatives focused on implications of climate change and ocean deoxygenation on marine life. This award was co-funded by the GEO-Division of Ocean Sciences Biological Oceanography Program and the BIO-Division of Integrative Organismal Systems Physiological Mechanisms and Biomechanics Program.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.