The role of light in mediating the effects of ocean acidification on coral calcification

• Published in: Journal of Experimental Biology
• Main Authors: Dufault, Aaron M., Ninokawa, Aaron, Bramanti, Lorenzo, Cumbo, Vivian R., Fan, Tung-Yung, Edmunds, Peter J.
• Format: Text
• Language: English
• Published: Company of Biologists 2013
• Subjects: Research Article; Ocean acidification
• Online Access: http://jeb.biologists.org/cgi/content/short/jeb.080549v1; https://doi.org/10.1242/jeb.080549

We tested the effect of light and pCO 2 on the calcification and survival of Pocillopora damicornis recruits settled from larvae released in southern Taiwan. In March 2011, recruits were incubated at 31, 41, 70, 122, and 226 μmol photons m-2s-1 under ambient (493 μatm) and high pCO 2 (878 μatm). After 5 days calcification was measured gravimetrically and survivorship estimated as the number of living recruits. Calcification was affected by the interaction of pCO 2 with light, and at 493 μatm pCO 2 the response to light intensity resembled a positive parabola. At 878 μatm pCO 2 , the effect of light on calcification differed from that observed at 493 μatm pCO 2 , with the result that there were large differences in calcification between 493 μatm and 878 μatm pCO 2 at intermediate light intensities (ca. 70 μmol photons m-2s-1), but similar rates of calcification at the highest and lowest light intensities. Survivorship was affected by light and pCO 2 , and was highest at 122 μmol photons m-2s-1 in both pCO 2 treatments, but was unrelated to calcification. In June 2012 the experiment was repeated, and again the results suggested that exposure to high pCO 2 decreased calcification of P. damicornis recruits at intermediate light intensities, but not at lower or higher intensities. Together, our findings demonstrate that the effect of pCO 2 on coral recruits can be light-dependent, with inhibitory effects of high pCO 2 on calcification at intermediate light intensities that disappear at both higher and lower light intensities.