The growth and development of the aragonitic CaCO3 otoliths of teleost fish could be vulnerable to processes resulting from ocean acidification. The potential effects of an increase in atmospheric CO2 on the calcification of the otoliths were investigated by rearing Atlantic cod Gadus morhua L. larvae in 3 pCO2 concentrations-control (370 µatm), medium (1800 µatm) and high (4200 µatm)-from March to May 2010. Increased otolith growth was observed in 7 to 46 d post hatch (dph) cod larvae at elevated pCO2 concentrations. The sagittae and lapilli were usually largest in the high pCO2 treatment followed by the medium and control treatments. The greatest difference in mean otolith surface area (normalized to fish length) was for sagittae at 11 dph, with medium and high treatments being 46 and 43% larger than the control group, respectively. There was no significant pCO2 effect on the shape of the otoliths nor were there any trends in the fluctuating asymmetry, defined as the difference between the right and left sides, in relation to the increase in otolith growth from elevated pCO2.

European Community's Seventh Framework Programme (FP7/ 2007-2013) under the Marie Curie Initial Training Network 'Calcification by Marine Organisms' (CalMarO)RTD project 'European Project on Ocean Acidification' (EPOCA), grant agreement (N211384)'Biological Impacts of Ocean ACIDification' (BIOACID), funded by the German Ministry for Education and Research (BMBF)In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne and Gattuso, 2011) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010).

Supplement to: Maneja, Rommel H; Frommel, Andrea Y; Geffen, Audrey J; Folkvord, Arild; Piatkowski, Uwe; Chang, M Y; Clemmesen, Catriona (2013): Effects of ocean acidification on the calcification of otoliths of larval Atlantic cod Gadus morhua. Marine Ecology Progress Series, 477, 251-258