Paper Reviewed
Andrade, J.F., Hurst, T.P. and Miller, J.A. 2018. Behavioral responses of a coastal flatfish to predation-associated cues and elevated CO2. Journal of Sea Research 140: 11-21.

According to Andrade et al. (2018), only one study to date has investigated the effects of ocean acidification (OA) on flatfish behavior; and that study was conducted by Sampaio et al. (2016). Thus, it was the desire of these three U.S. researchers to obtain some additional information on the subject.

To accomplish their objective, Andrade et al. examined the effects of elevated CO2 levels (~900 µatm and ~1500 µatm) on the posture, activity, foraging and behavioral responses to a predation-associated cue of speckled sanddab (Citharichthys stigmaeus). Fish specimens were collected from Yaquina Bay, Oregon, and acclimated under treatment conditions in the laboratory for 4-6 weeks prior to examination; while the responses of the fish during their trials were then examined via contemporary video recordings.

And what did the results of the experiment reveal? Quite simply, they revealed that there was no significant impact of elevated CO2 on any of the behavioral characteristics examined. And in regard to this resiliency, Andrade et al. opine that "it may be related to their distribution in a coastal upwelling region with seasonally elevated CO2 levels" that can reach 1000 µatm or more. Or, as a second possibility, they write that "the observed resiliency of speckled sanddab may be related to the experimental approach or the specific set of behaviors examined," noting that "the 4-6 week acclimation time to elevated CO2 conditions used in this study is longer than that applied in many studies that have shown OA-induced behavioral disruptions."

Whatever the reason, one thing is certain, predicted negative effects of ocean acidification on fish species are, quoting the authors, "far from universal." And that is good news for those concerned about the potential impacts of OA on marine life.

Reference
Sampaio, E., Maullvault, A.L., Lopes, V.M., Paula, J.R., Barbosa, V., Alves, R, Pousao-Ferreira, P., Repolho, T., Marques, A. and Rosa, R. 2016. Habitat selection disruption and lateralization impairment of cryptic flatfish in a warm, acid, and contaminated ocean. Marine Biology 163: 217, doi: 10.1007/s00227-016-2994-8.