For over a decade, scientists have warned that the acidification of ocean water could decimate fish populations. Acidification changed fish behavior, several studies found, making them less likely to evade predators.
As carbon emissions pushed pH levels higher and higher, climate advocates sounded an apocalyptic tone. Fewer fish would mean fewer fisheries, which would imperil the livelihoods of millions of fishermen across the globe. It could also mean fewer medicines, many of which are derived from marine life.
According to a new paper in a top-ranked biology journal, these concerns are vastly overblown.
The paper, published in PLOS Biology on Feb. 3, reviewed 91 studies of the effect of ocean acidification on fish behavior. It found that better-quality studies tended to find smaller effects on fish behavior—and that the studies with the most dramatic results tended to have low sample size, making them less statistically reliable.
Those lower-quality studies are nonetheless "published in high-impact journals and have a disproportionate influence," the authors said. "We contend that ocean acidification has a negligible direct impact on fish behavior."
The paper adds to a growing body of evidence for the so-called replication crisis, in which scientific findings fail to hold up upon repeated testing. While the crisis is thought to be most acute in the social sciences, it has also affected medicine and biology: Many findings in cancer research, for example, fail to replicate.
The PLOS Biology paper is not the first to question the consensus on ocean acidification. A 2020 study in Nature found that "ocean acidification does not impair the behavior of coral reef fishes."