EFFECT OF OCEAN ACIDIFICATION ON GROWTH AND OXYGEN CONSUMPTION OF FALSE CLOWNFISH Amphiprion ocellaris

Abstract

There is widespread concern that increase of CO₂ levels affects essential physiological processes of many aquatic organisms, impact on marine diversity and ecosystem function. Yet the ability for coral reef fish at early life stage to adjust their growth, size-based hierarchies and metabolic rate to elevated CO₂ concentrations are limited. In this study, newly settling juvenile clownfish Amphiprion ocellaris were ranked, tagged and exposed to three different ocean acidification scenarios: control (present condition, PCO₂403 µatm, pH 8.0), moderate acidification (PCO₂806µatm, pH 7.7), and high acidification (PCO₂1445 µatm, pH 7.4). Fish growth (body weight and total length), size-based hierarchies and oxygen consumption were measured at the half and the end of 38 days of the experiment. Our results suggest juvenile A. ocellaris are tolerant of moderate increases in environmental CO₂, but further acidification of the ocean have a significant effect on growth and initially induced the changes in relative size of a fish in rank. Energy cost for maintaining homeostasis in juvenile coral reef fish under ocean acidification might not result in an increase of the metabolic rate.