Logo image
Back
Evaluating coral fogging as a mass bleaching intervention tool and improving optical measures of pigmentation
Thesis   Open access

Evaluating coral fogging as a mass bleaching intervention tool and improving optical measures of pigmentation

Conor Augustus Hendrickson
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2026
DOI:
https://doi.org/10.25918/thesis.608
Appears in  Recent Southern Cross PhD Theses
pdf
Hendrickson C PhD 20266.06 MBDownloadView
Open

Metrics

1 File views/ downloads
2 Record Views

Abstract

coral bleaching solar radiation management coral pigmentation imaging spectroscopy
Coral reef ecosystems are severely threatened by anthropogenic climate change. Rising ocean temperatures, which can be exacerbated by high levels of solar radiation, drive mass bleaching events that endanger reefs globally. Shading coral during high-stress events can ameliorate a portion of the environmental stress on corals and may reduce bleaching. However, shading at reef-level scales is not feasible using shade cloths and other rigid structures. Larger reef areas could be shaded via aerosol generation from marine cloud brightening or seawater fogging. The stress-reduction capabilities of lower levels of shade (<40%) that represent feasible targets for these large-scale fogging/shading methods are not well understood. In this thesis, laboratory-based simulated bleaching experiments were conducted to investigate the effect of seawater fog on corals for the first time. These studies found the variable shading from the seawater fog was able to reliably reduce irradiance and mitigate a portion of bleaching stress, but that there is likely a minimum shading threshold that must be met for the shading to have an effect. Additionally, shading from seawater fog continued to benefit coral and enhance their recovery after the heat-stress period ended. As global demand and the necessity of reef restoration escalate, there will be an increased need for accessible and efficient ways to measure the success of interventions like seawater fogging. In this thesis, commonly used colour-based bleaching metrics were compared, a low-cost hyperspectral imaging technique was investigated and recommendations for implementation and improvement of the methods are provided. Key findings include: 1) Commonly used colour-based bleaching metrics performed comparably to hyperspectral indices for predicting coral pigment content, though RGB imaging and hyperspectral imaging provide other advantages like spatial data and cross-study comparability. 2) The low-cost hyperspectral camera produced spectral shapes similar to a commercial hyperspectral camera but was unable to resolve finer differences in coral reflectance due to bleaching; this suggests that the current design is better suited to classification tasks rather than quantitative stress detection. Together, these findings address two areas critical to reef restoration: scalable interventions to protect coral ecosystems, and accessible and accurate methods to detect bleaching and measure reef health. These findings may help inform management strategies to preserve vulnerable reef ecosystems in the coming decades.

Details

Logo image