Understanding the Impacts of Future Fluctuating CO2 Concentrations on the Behavior of Amphiprion percula

As human activity and production of atmospheric CO₂ increases, there is a corresponding increase in pCO₂ in shallow ocean waters, leading to a decrease in pH - coined ocean acidification. This increase in pCO₂ and corresponding decrease in pH in ocean waters has been shown to have significant impacts on tropical coral reef fish behavior. Most ocean acidification research to date focused on the impact a static pCO₂ change would cause when compared to a static present day control pCO₂. However, the living photosynthetic organisms in the shallow ocean waters, such as corals, anemones, and seaweeds absorb CO₂ and respire O₂ during the photosynthetic period, and only respire CO₂ at night. These photosynthetic organisms significantly impact the local CO₂ concentration, which may impact the extent ocean acidification will impact fish behavior, especially in species tightly coupled with a photosynthetic host. Here, we examine how both static and diel fluctuating elevated pCO₂ impacts behavioral lateralization, or the preference for left or right. This behavior is indicative of increased neural network efficiency and corresponds to improved task performance. Amphiprion percula, a common Indo-Pacific reef anemonefish was exposed to four pCO₂ treatments over the course of five days: present day static (500ppm CO₂), present day fluctuating (500-700ppm CO₂), future day static (850ppm CO₂), and future day fluctuating (850-1000ppm CO₂). Significant differences in both the CO₂ treatment and days in treatment were detected. This research not only supports the findings of previous work when comparing the research of both present day and future day static pCO₂ exposure, but advances the field of ocean acidification by incorporating diel fluctuations in an ecologically relevant anemonefish species. It is vital that we incorporate the most realistic exposure treatment when making predictions on future oceans.