We tested the hypothesis that taxonomically diverse cnidarians display dissimilar responses to ocean acidification (OA), and did so by comparing the individual responses to OA of one hydrocoral and three scleractinians. The hydrocoral Millepora platyphylla and the scleractinians massive Porites spp., Acropora pulchra and Pocillopora meandrina provided a contrast of three clades of calcifying cnidarian (Milleporidae, Robusta, and Complexa). Corals were collected from the shallow back reef of Moorea, French Polynesia, and were incubated under orthogonal contrasts of 408 and 913 μatm pCO2, and 28.0 and 30.1 °C. After 19 days in these treatments, calcification of P. meandrina was reduced 55 % at 913 μatm pCO2 and 30.1 °C, but the calcification of the other three taxa was unaffected by high pCO2 at 30.1 °C; the calcification of all taxa was unaffected by high pCO2 at 28.0 °C. These results show that P. meandrina (Robusta) was strongly and negatively affected by OA, whereas A. pulchra and massive Porites spp. (Complexa) and M. platyphylla (milleporine) were unaffected by OA. The assignment of these taxa to different clades suggests that evolutionary constraints could play a role in determining the sensitivity of cnidarian calcification to OA.
Brown D. & Edmunds P. J., 2016. Differences in the responses of three scleractinians and the hydrocoral Millepora platyphylla to ocean acidification. Marine Biology 163:62. Article (subscription required).
