Warming has a greater effect than elevated CO on predator-prey interactions in coral reef fish.

Ocean acidification and warming, driven by anthropogenic CO emissions, are considered to be among the greatest threats facing marine organisms. While each stressor in isolation has been studied extensively, there has been less focus on their combined effects, which could impact key ecological processes. We tested the independent and combined effects of short-term exposure to elevated CO and temperature on the predator-prey interactions of a common pair of coral reef fishes ( and its predator, ). We found that predator success increased following independent exposure to high temperature and elevated CO Overall, high temperature had an overwhelming effect on the escape behaviour of the prey compared with the combined exposure to elevated CO and high temperature or the independent effect of elevated CO Exposure to high temperatures led to an increase in attack and predation rates. By contrast, we observed little influence of elevated CO on the behaviour of the predator, suggesting that the attack behaviour of was robust to this environmental change. This is the first study to address how the kinematics and swimming performance at the basis of predator-prey interactions may change in response to concurrent exposure to elevated CO and high temperatures and represents an important step to forecasting the responses of interacting species to climate change.