Researchers report development of an airborne approach for large-scale mapping of live coral distribution in the Hawaiian Islands to depths of 16 meters. Coral, the foundational species of tropical reefs, are under pressure from marine heat waves, coastal development, and other factors. Gregory Asner and colleagues sought to fill the gap between the high resolution but limited coverage field surveys and low resolution satellite imaging using an airborne mapping strategy and deep learning models. The authors collected data from above the eight main Hawaiian Islands at an altitude of 2 km by employing laser-guided imaging spectroscopy to capture 95% of known shallow reefs up to a depth of 16 m. They developed a deep learning model, trained with approximately 37,000 data points, to analyze the percentage of live coral in a given map section. Geospatial modeling with the resulting map suggested that, in addition to natural factors like maximum wave power that positively affect live coral cover, nearshore development negatively regulates live coral cover. According to the authors, at a cost of approximately $4 per hectare to operate at the scale of the Hawaiian Islands, this airborne mapping strategy could provide a cost-effective option for ongoing, high-resolution monitoring of coral health in island archipelagos.
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Article #20-17628: "Large-scale mapping of live corals to guide reef conservation," by Gregory P. Asner et al.
MEDIA CONTACT: Gregory P. Asner, Arizona State University, Tempe, AZ; tel: 1-808-757-9194; e-mail: < gregasner@asu.edu >
Proceedings of the National Academy of Sciences