Photophysiology and molecular responses of the soft coral Sarcophyton cf glaucum exposed to heat and high light stress

An experiment testing different temperatures (26 vs 32 ºC) and light intensities (high light HL and low light LL, ∼662 and 253 µmol photons m^-2 s^-1) was carried out using the soft coral Sarcophyton cf glaucum (leather coral) as model species.

In summary, corals were exposed to the different light intensities for 30 days (Photoacclimation, time-point 1) and a subsequent marine heatwave simulation was carried out for 10 days (Marine heatwave, time-point 2). Subsequently, corals were returned to control temperature and allowed to recover for 30 days (Recovery, time-point 3). Photophysiological performance (maximum quantum yield of photosystem II (Fv/Fm), a measure of photosynthetic activity; dark-level fluorescence (F₀), as a proxy of chlorophyll a content; and zooxanthellae density) and stress biomarkers (total protein, catalase - CAT, superoxide dismutase - SOD, glutathione-S-transferase - GST, total antioxidant capacity - TAC, lipid peroxidation - LPO, ubiquitin - UBI, and heat shock protein 70 - Hsp70) were assessed in corals at these three time-points.