Juvenile fish must immediately learn to catch prey and to escape enemies. Additionally, at this stage of their lives, they are highly sensitive to environmental factors such as temperature, oxygen and the pH of the water. These factors are currently changing on a global scale—temperature is rising, the oxygen content of the ocean is decreasing and more carbon dioxide (CO2) from the atmosphere is dissolving in the seawater, where it forms carbonic acid and lowers the pH level. But indirectly elevated CO2 also affects the survival of fish larvae, because it can change their food supply.