Between the acidic reef and the normal reef, species abundance, richness, and composition seemed to be unchanged. "The fish are metabolically the same between the control reef and the CO2 reef," Dixson says. "At this point, we have only seen effects on their behavior." What's more, acidic reefs tend to be safer places for fish, with fewer concentrations of predators in the first place. So, there's a possibility the projected acidification could be a wash, at least in terms of fish mortality.