Thermal priming and bleaching hormesis in the staghorn coral, Acropora cervicornis (Lamarck 1816)
Article
Martell, HA. (2023). Thermal priming and bleaching hormesis in the staghorn coral, Acropora cervicornis (Lamarck 1816)
. JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY, 560 10.1016/j.jembe.2022.151820
Martell, HA. (2023). Thermal priming and bleaching hormesis in the staghorn coral, Acropora cervicornis (Lamarck 1816)
. JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY, 560 10.1016/j.jembe.2022.151820
Stress memory is a highly conserved phenomenon that enables the survival of organisms. There is evidence of stress memory in stony corals, but its costs and benefits remain largely unknown. To characterize coral stress memory, eight genets of Acropora cervicornis corals were primed with varying doses of thermal stress in the laboratory, allowed to recover for eight days and then experimentally bleached. Symbiont density and chlorophyll decreased linearly with increasing priming intensity, demonstrating a dose-dependent upfront ‘cost’ of priming. The highest priming dose (8.8 °C·days) led to bleaching after priming and mortality at the end of the recovery period, however, in lower priming intensity treatments, differences in symbiont density and chlorophyll detected immediately after priming did not persist after recovery. Primed corals did not bleach significantly less than naïve corals, owing to high within treatment variance between genets. However, the relationship between priming intensity (°C·days) and thermal bleaching severity (i.e., symbiont density) was hormetic (p = 0.055). Priming with low doses of thermal stress (1.8 to 4.6 °C·days) resulted in 32–51% greater symbiont retention, but the highest dose (8.8 °C·days) led to severe bleaching like that observed in naïve corals. This study empirically demonstrates coral bleaching hormesis in the laboratory, providing support for environmentally mediated priming in Scleractinians. The presence of coral bleaching hormesis suggests there may be the potential to extend resilient bleaching phenotypes for some corals. However, not all host genotypes may benefit from hardening, an essential consideration in the applicability of stress hardening for coral restoration.
