Ocean Acidification: Implications for Respiratory Gas Exchange and Acid-Base Balance in Estuarine Fish

人为二氧化碳释放正在造成海洋碳酸盐系统（二氧化碳分压、pH值和碱度）的前所未有的变化，如果目前的趋势继续下去，海洋二氧化碳分压可能在世纪结束前达到1 000 µatm。海洋化学的这种预测变化已被证明会以多种方式影响海洋鱼类，从感官和行为干扰到生长和生存减少。据估计，这些累积影响将深刻影响全球鱼类种群;然而，要真正理解海洋酸化对种群的影响，关键是要了解影响个体的潜在生理机制。呼吸是控制体内PCO 2水平和酸碱状态的关键生理过程，因此在考虑海洋酸化的影响时尤为重要。最近的研究表明，海洋酸化会损害鱼类的二氧化碳排泄，导致代偿性呼吸性酸中毒，并对肠道水平衡产生下游生理影响。这项研究将侧重于河口红鼓，通过继续调查海洋酸化的呼吸和酸碱后果，以及应对环境变化的生理适应潜力，建立在以前的工作基础上。更具体地说，这项工作将研究与呼吸气体交换和海洋酸化的酸碱影响相关的三个具体领域：1）河口鱼类对海洋酸化的净化反应，2）呼吸气体交换途径对海洋酸化的适应能力，以及3）酸碱调节的个体发育及其在确定幼体对海洋酸化敏感性方面的作用。这些研究将利用分子生物学、生物化学和整个动物生理学的结合，对一个内在的综合过程进行深入研究。此外，这项工作不仅将寻求提供海洋酸化的最坏情况，而且还将调查应对这一前所未有的环境变化的生理适应的可能途径。这些研究活动将培养多名本科生和研究生，以及一名博士后研究员。这项工作的结果还将用于各种外联方案，旨在向公众宣传海洋酸化对鱼类种群的影响。

Anthropogenic carbon dioxide release is causing unprecedented change in the oceanic carbonate system (partial pressure of CO2, pH and alkalinity), and if current trends continue ocean PCO2 could reach 1,000 µatm before the end of the century. This predicted change in ocean chemistry has been shown to impact marine fish in a number of ways, from sensory and behavioral disturbances to reduced growth and survival. These cumulative impacts are estimated to profoundly affect global fish populations; however, to truly comprehend the population level consequences of ocean acidification, it is crucial to understand the underlying physiological mechanisms that impact individuals. Respiration is the key physiological process governing internal PCO2 levels and acid-base status, and therefore is particularly important when considering the impacts of ocean acidification. Recent work has shown ocean acidification to impair CO2 excretion in fish, resulting in a compensated respiratory acidosis with downstream physiological implications related to intestinal water balance. This research will focus on the estuarine red drum to build upon previous work through continued investigation of the respiratory and acid-base consequences of ocean acidification, as well as the potential for physiological adaptations in response to environmental change. More specifically this work will examine three specific areas related to respiratory gas exchange and acid-base implications of ocean acidification: 1) the ventilatory responses to ocean acidification in estuarine fish, 2) the adaptive capacity of respiratory gas exchange pathways in response to ocean acidification, and 3) the ontogeny of acid-base regulation and its role in determining larval sensitivity to ocean acidification. These studies will provide an in-depth examination of an inherently integrative process, using a combination of molecular biology, biochemistry and whole animal physiology. Furthermore, this work will not only seek to provide a worst-case scenario for ocean acidification, but also investigate possible routes of physiological adaptation in response to this unprecedented environmental change. These research activities will train multiple undergraduate and graduate students, as well as one post-doctoral researcher. The findings of this work will also be used in a variety of outreach programs intended to inform the public about the impacts of ocean acidification on fish populations.