In the academic equivalent of “shots fired,” a newly published paper evaluates a number of prior studies on the effects of ocean acidification on fish—and finds it can’t replicate any of the results.

A number of studies in recent years has conducted experiments on the behavior of coral fish in normal and high-CO₂ water. (Increasing dissolved CO₂—which is happening due to human-caused emissions—lowers the pH of seawater, hence the term “acidification.”) These studies have found some surprising impacts, from a failure to recognize and avoid the smell of a predator to a loss of “handedness” (preferring left or right turns) during development. These behaviors have been linked to CO₂ interfering with a specific receptor in the brain.

Individual variation

But a group of researchers found itself skeptical of these results and hatched a plan to replicate them in a standardized experimental setup. Over the course of several years, the researchers repeated some of these experiments with a variety of fish species, carefully documenting and filming each step to create an accessible database of results. And those results seem markedly different.