Award: EF-1416917

Nearshore marine species inhabiting upwelling ecosystems such as the California Current are exposed to low levels of pH and dissolved oxygen (DO) during periods of seasonal upwelling. These episodes mimic future climate change scenarios resulting from the anthropogenic release of CO2 and subsequent ocean acidification (OA) and serve as a model for examining of the combined effects of OA and DO. Although marine fishes have generally been presumed to be tolerant of OA due to their competence in acid-base regulation, few studies have addressed the potential interactive effects of a low pH, low DO environment. This study used 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. The project used 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 were captured in the field and then reared in the lab using different combination of DO/OA factors and exposure times to simulate changes under four different environmental conditions: 1) Independent effects of OA and DO; 2) Independent and synergistic effects of OA and DO, and 3) Static vs. simulated upwelling using OA and DO. We measured responses in the changes in olfactory capabilities, brain functional asymmetry and problem-solving ability; and in the effects on swimming capabilities, respiration, aerobic performance, and growth. We found that: 1) reductions in DO appear to have a much stronger effect than changes in pH on rockfish; 2) there was a potential for synergistic effects of pH and DO; 3) effects of ph/DO exposure manifest over a time scale of days and hours; 4) copper and black rockfish have the ability to recover from these effects in 5-6 days. Neither brain lateralization nor escape trials indicated strong effects associated with exposure to reduced pH or DO, with one exception: faster escape by copper rockfish at reduced DO. This might be a response to seek better-oxygenated water during oxygen stress. 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. The broader impacts of the project include training opportunities for graduate and undergraduate students and an elementary school teacher. Results were communicated to fisheries management agencies, the science community, and the public to provide information on potential climate change impacts on economically and ecologically valuable groundfish. The laboratory facility used to conduct the study is a now a major contributor to new studies at the marine laboratories on climate change involving DO and OA. Last Modified: 12/03/2018 Submitted by: Brian N Tissot