Early Life History Determines the Effects of Ocean Acidification on the Behavior and Physiology of Juvenile Rockfishes in Central California

The rapid increase of anthropogenic carbon dioxide (CO₂) emissions to the atmosphere is altering seawater chemistry at an alarming rate. Many studies have shown that elevated dissolved seawater CO₂ (i.e. pCO₂) concentrations and associated decreases in seawater pH will have negative impacts on marine organisms that secrete calcium carbonate structures. Recent research has shown that decreased pH affects the behavior and physiology of several tropical and temperate fishes, but some species appear to be resilient to near future pH levels. We investigated how two early life history strategies of Central California nearshore rockfishes determine susceptibility to pH mediated behavioral and physiological impairments. We reared three canopy recruiting rockfish species and three benthic recruiting rockfish species in 4 pH treatments (8.0, 7.8, 7.5, and 7.2) for 3 months. During that time, we examined the effect of decreased pH on behavioral lateralization, critical swimming speed, and aerobic scope. We found that benthic recruiting species appear resistant to pH-mediated impairments while canopy recruiting species suffer behavioral and physiological impairments at low pH.  These findings indicate that ocean acidification may differentially affect the fitness of Central California nearshore rockfishes, which could alter the species composition of California’s kelp forests in the future.