Bignami, S., Enochs, I. C., Manzello, D. P., Sponaugle, S., Cowen, R. K.

Ocean acidification alters the otoliths of a pan-tropical fish species with implications for sensory function

2013

University of Miami

Proceedings of the National Academy of Sciences

110

18

7366-7370

"Ocean acidification affects a wide diversity of marine organisms and is of particular concern for vulnerable larval stages critical to population replenishment and connectivity. Whereas it is well known that ocean acidification will negatively affect a range of calcareous taxa, the study of fishes is more limited in both depth of understanding and diversity of study species. We used new 3D microcomputed tomography to conduct in situ analysis of the impact of ocean acidification on otolith (ear stone) size and density of larval cobia (Rachycentron canadum), a large, economically important, pantropical fish species that shares many life history traits with a diversity of high-value, tropical pelagic fishes. We show that 2,100 units of microatmospheres partial pressure of carbon dioxide (pCO2) significantly increased not only otolith size (up to 49% greater volume and 58% greater relative mass) but also otolith density (6% higher). Estimated relative mass in 800 units of microatmospheres pCO2 treatments was 14% greater, and there was a similar but nonsignificant trend for otolith size. Using a modeling approach, we demonstrate that these changes could affect auditory sensitivity including a about 50% increase in hearing range at 2,100 units of microatmospheres pCO2, which may alter the perception of auditory information by larval cobia in a high-CO2 ocean. Our results indicate that ocean acidification has a graded effect on cobia otoliths, with the potential to substantially influence the dispersal, survival, and recruitment of a pelagic fish species. These results have important implications for population maintenance/replenishment, connectivity, and conservation efforts for other valuable fish stocks that are already being deleteriously impacted by overfishing."

National Coral Reef Monitoring Plan (NCRMP); climatic monitoring

10.1073/pnas.1301365110

FY2013 CRCP Project ID 743; Project Title: National Coral Reef Monitoring Plan (NCRMP) Implementation (Climatic Monitoring); Principal Investigator: Jessica Morgan