Large-scale mapping of live corals to guide reef conservation

Area of Science:

• Marine Biology
• Ecology
• Remote Sensing

Background:

• Coral reefs are vital marine ecosystems threatened by ocean warming and human activities.
• Accurate, large-scale mapping of live coral cover is essential for effective reef management and conservation.
• Current methods often lack the scale and detail needed for broad policy-relevant assessments.

Purpose of the Study:

• To develop and validate an airborne mapping approach for quantifying live coral cover across the Hawaiian archipelago.
• To assess the condition of coral reefs and identify potential refugia using high-resolution coral cover data.
• To understand the key environmental and human-driven factors influencing live coral distribution.

Main Methods:

• Combined airborne laser-guided imaging spectroscopy with deep learning models for coral cover quantification.
• Validated airborne estimates against extensive field-based measurements, achieving high correlation (R² = 0.94).
• Utilized geospatial modeling to analyze factors driving coral cover variation.

Main Results:

• Generated large-scale maps of live coral distribution down to 16-m water depth across the main Hawaiian Islands.
• Identified significant correlations between airborne and field-based live coral cover estimates.
• Found that water depth, wave power, and nearshore development were major drivers of coral cover variation (>60%).

Conclusions:

• The developed airborne mapping approach is a reliable tool for assessing live coral cover at ecologically relevant scales.
• The generated maps provide critical insights into reef condition, identifying potential coral refugia and informing management strategies.
• Understanding the interplay of natural and anthropogenic factors is key to guiding environmental management for enhanced coral reef resiliency.