Large-amplitude internal waves benefit corals during thermal stress

Area of Science:

• Marine Biology
• Oceanography
• Climate Change Science

Background:

• Tropical corals are vulnerable to rising sea surface temperatures (SSTs) due to global warming.
• Elevated SSTs cause coral bleaching and mortality by disrupting coral-algal symbiosis.
• Local variations in coral bleaching severity are not fully explained by regional SST anomalies.

Purpose of the Study:

• To investigate the role of internal waves in local coral bleaching and mortality patterns.
• To understand how internal wave activity mitigates or exacerbates coral bleaching during thermal stress events.
• To identify potential conservation strategies for coral reefs in a warming climate.

Main Methods:

• Analysis of coral bleaching and mortality data in the Andaman Sea during a May 2010 SST anomaly.
• Correlation of local bleaching patterns with the occurrence of large-amplitude internal waves (LAIW).
• Observation of cold water intrusions associated with breaking LAIW.

Main Results:

• Frequent cold water intrusions from breaking LAIW mitigated coral bleaching and mortality in shallow waters.
• LAIW-sheltered areas experienced severe bleaching and total mortality in susceptible coral species.
• Internal waves play a significant role in determining local coral bleaching severity.

Conclusions:

• Large-amplitude internal waves (LAIW) act as a protective mechanism for coral reefs during thermal stress.
• The swash zones of LAIW can serve as crucial refugia for bleaching-susceptible corals.
• Incorporating LAIW dynamics into predictive models can enhance coral reef conservation and management strategies.