Coral tissue depth reconstructed using skeletal microstructural offsets is driven by environmental stress.

Area of Science:

• Marine Biology
• Paleoclimatology
• Geochemistry

Background:

• Coral tissue depth is a vital indicator of coral health and susceptibility to environmental changes.
• Reconstructing past coral tissue depth on seasonal timescales has been a significant challenge in marine science.

Purpose of the Study:

• To develop a novel method for reconstructing seasonal coral tissue depth.
• To investigate the influence of environmental stressors, such as thermal stress and volcanic events, on coral tissue depth.

Main Methods:

• Utilized spatial offsets between growth cycles in corallite porosity and geochemical proxies (Li/Mg, Ba/Ca) from a Siderastrea siderea coral core.
• Analyzed geochemical signatures and porosity variations to infer changes in coral tissue depth over time.

Main Results:

• Demonstrated systematic variations in coral tissue depth over multiyear timescales.
• Observed decreased tissue depth linked to thermal stress, affecting coral extension and calcification.
• Documented significant impacts on tissue depth following the 2021 La Soufrière volcanic eruption, likely due to ash deposition and metal release.

Conclusions:

• The developed method provides a robust tool for reconstructing past seasonal coral tissue depth.
• Coral tissue depth variations are sensitive indicators of both chronic (thermal stress) and acute (volcanic events) environmental disturbances.
• Further validation across multiple coral colonies can enhance the reconstruction of regional and global environmental stressors.