Physiological responses (Hsps 60 and 32, caspase 3, H2O2 scavenging, and photosynthetic activity) of the coral Pocillopora damicornis under thermal and high nitrate stresses

• Published in: Marine pollution bulletin 2021-10, Vol.171, p.112737, Article 112737
• Main Authors: Thummasan, Montaphat, Casareto, Beatriz Estela, Ramphul, Chitra, Suzuki, Toshiyuki, Toyoda, Keita, Suzuki, Yoshimi
• Format: Article
• Language: English
• Subjects: Apoptosis; Bleaching; Caspase 3 and apoptosis; Caspase-3; Combined stress; Corals; Density; Discoloration; Heat shock; Heat shock proteins; High nitrate stress; Hsp60 and 32; Hsp60 protein; Hydrogen peroxide; Nitrates; Oxidation; Oxidative stress; Photosynthesis; Physiological responses; Physiology; Pocillopora damicornis; Scavenging; Symbiodiniaceae; Thermal stress; Tissue
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2021.112737

This study explored the physiological responses of the coral Pocillopora damicornis to high nitrate concentrations and thermal stresses. The expression of heat shock proteins Hsp60 and Hsp32, Symbiodiniaceae density, Chl a concentration, Fv/Fm, H2O2 scavenging, and caspase 3 activity varied during 60 h incubations at 28 °C or 32 °C, ambient or high nitrate (~10 μM) concentrations, and their combinations. In combined stresses, corals showed a rapid and high oxidation level negatively affecting the Symbiodiniaceae density and Chl a concentration at 12 h, followed by caspase 3 and Hsps upregulations that induced apoptosis, bleaching and tissue detachment. Corals under thermal stress showed the highest oxidation and upregulation of Hsps and caspase 3 resulting in coral discoloration. High nitrate treatment alone did not seriously affect the coral function. Results showed that combined stress treatment severely affected coral physiology and, judging from the condition of detached tissues, these corals might have lower chances to recover. •Physiological responses of P. damicornis to NO3- and thermal stresses were studied.•High temperature and NO3- concentration caused coral bleaching and tissue detachment.•Hsps and caspase 3 upregulation was high under thermal and combine stress.•Combined stresses affected the Symbiodiniaceae density and Chl a concentration.•The findings can boost effective coral reef management in developed coastal areas.