Climate change threatens coral reef fishes in myriad ways, but maybe not in all the ways we thought. Some studies have suggested that ocean acidification, one consequence of climate change, might warp fish behavior. But new research shows that fish may be far more resilient.
Scientists predict that as atmospheric carbon dioxide levels continue to rise, and oceans absorb even more, the waters will increasingly acidify. About a decade ago, a series of high-profile studies alarmed biologists with reports of severe behavioral impairments in coral fishes exposed to mildly acidified water. Larval fish lost the ability to smell predators and became dangerously hyperactive and confused when exposed to ocean acidification levels projected for 2100 if fossil fuel use continues at current levels (SN: 7/6/10). Research into the effects of ocean acidification then ballooned, becoming one of the most studied subjects in marine science.
But a three-year attempt to replicate and improve upon some of those earlier studies paints a starkly different picture. Tests of over 900 individuals from six different species of coral reef fish showed that exposure to acidified waters had no significant adverse effects on fish activity or predator avoidance, researchers report January 8 in Nature.
“Climate change is a huge threat to reef fishes,” says Timothy Clark, a comparative physiologist at Deakin University in Geelong, Australia. But “the acidification levels we’ll see by the end of this century aren’t going to have any real impact on fish, even beyond just coral reef fish.”