Figure 8. Calcification rate of corals by genotype and previous temperature treatment.

Calcification rate by coral genotype and temperature preconditioning group (ambient vs high temperature) after 1 year while on trees during a natural warming event. For both species, only genotype main effects were significant (A) M. capitata (p = 0.0004) and (B) M. flabellata (p = 0.0002). Temperature preconditioning main effects were not significant (M. capitata p = 0.82; M. flabellata p = 0.49), and there was no significant interaction between genotype and temperature group (p = 0.92 and p = 0.91, respectively). For both species, exposure to elevated temperatures while in mesocosms did not benefit growth during a heat stress event in the ocean nursery. Variation in growth is explained by genotype but not previous temperature stress-hardening exposure. Error bars are SE, and different letters indicate significant difference among genotypes.