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.
