Key Takeaways & Executive Findings
- •• • Cyphastrea japonica exhibits a shock wave tolerance threshold of 6.74 MPa; beyond 8.82 MPa, protein content drops by up to 59.6%, indicating severe host tissue damage. • • At 11.01 MPa, zooxanthellae density decreases by 87% and photosynthetic rate by 49%, directly linking shock wave intensity to coral bleaching. • • Antioxidant enzyme activities (superoxide dismutase and catalase) significantly decline with increasing shock wave pressure, compromising the coral's defense against oxidative stress. • • Shock wave exposure increases microbial community diversity at the phylum level and complexity at the genus level, potentially destabilizing the holobiont's symbiotic balance.
Abstract
Underwater blasting is indispensable for marine engineering, yet its shock waves can damage reef-building corals. This study investigated the physiological damage to Cyphastrea japonica holobiont from underwater explosion shock waves, examining coral host, symbiotic zooxanthellae, and microbiota. The coral's tolerance threshold was 6.74 MPa. Protein content decreased with increasing shock wave intensity, with a maximum reduction of 59.6%. At 11.01 MPa, zooxanthellae density dropped by 87% and photosynthetic rate by 49%, causing significant bleaching. Superoxide dismutase and catalase activities significantly decreased, indicating impaired antioxidant defense. Microbial community diversity at the phylum level increased significantly, and genus-level structure became more complex. The study reveals a stepwise damage pathway from host to zooxanthellae photosynthesis to microbial community, providing scientific basis for coral protection during marine blasting.
1. Introduction
Underwater blasting remains essential for marine construction, yet its shock waves pose a significant threat to sessile reef-building corals, which cannot evade disturbances. Previous research on blast effects has focused on fish, sea turtles, and mammals, but the impact on coral holobionts—comprising the host, symbiotic zooxanthellae, and associated microbiota—has been largely unexplored. This study addresses the gap by systematically quantifying physiological responses of Cyphastrea japonica to controlled underwater explosions.
Existing studies on coral stress have centered on climate change, ocean acidification, and pollution, but none have established dose-response relationships for shock wave pressure. By employing a controlled experimental setup with varying explosive charges, this research provides precise thresholds for protein loss, zooxanthellae mortality, and enzymatic dysfunction, offering critical data for environmental risk assessment in marine blasting operations.
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TAO Chen, LI Huiyu, WANG Xin, TANG Dan, SU Changwang, QIU Zhangsheng, TANG Tao, LIN Mingqing (2026). Physiological Damage Effects of Underwater Explosion Shock Waves on Cyphastrea japonica. Chinese Journal of Energetic Materials (含能材料). https://doi.org/10.11943/CJEM2026125
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Frequently Asked Questions
What is the exact pressure threshold at which Cyphastrea japonica begins to show physiological damage?
The tolerance threshold is 6.74 MPa. Below this, no significant protein loss or enzyme activity changes were observed. Above 8.82 MPa, protein content drops sharply, with a maximum reduction of 59.6%.
How does shock wave intensity affect zooxanthellae density and photosynthetic efficiency?
At 11.01 MPa, zooxanthellae density decreases by 87% and photosynthetic rate by 49%, indicating severe damage to the symbiotic algae and leading to coral bleaching.
What is the impact of shock waves on the coral's antioxidant defense system?
Superoxide dismutase and catalase activities significantly decrease with increasing shock wave pressure, indicating impaired antioxidant capacity and increased oxidative stress.
How does the microbial community respond to shock wave exposure?
Shock wave exposure increases microbial diversity at the phylum level and complexity at the genus level, suggesting a shift in community structure that may affect coral health.
Are there any visible skeletal damages at the highest tested pressure?
At 11.01 MPa, no macroscopic skeletal fractures were observed, but physiological indicators were severely compromised, suggesting that skeletal tissue may have a higher tolerance than soft tissues.
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