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Abstract Coral reefs support the world’s most diverse marine ecosystem and provide invaluable goods and services for millions of people worldwide. They are however experiencing frequent and intensive marine heatwaves that are causing coral bleaching and mortality. Coarse-grained climate models predict that few coral reefs will survive the 3 °C sea-surface temperature rise in the coming century. Yet, field studies show localized pockets of coral survival and recovery even under high-temperature conditions. Quantifying recovery from marine heatwaves is central to making accurate predictions of coral-reef trajectories into the near future. Here we introduce the world’s most comprehensive database on coral recovery following marine heatwaves and other disturbances, called Heatwaves and Coral-Recovery Database (HeatCRD) encompassing 29,205 data records spanning 44 years from 12,266 sites, 83 countries, and 160 data sources. These data provide essential information to coral-reef scientists and managers to best guide coral-reef conservation efforts at both local and regional scales.
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ReScape: transforming coral-reefscape images for quantitative analysis
Abstract Ever since the first image of a coral reef was captured in 1885, people worldwide have been accumulating images of coral reefscapes that document the historic conditions of reefs. However, these innumerable reefscape images suffer from perspective distortion, which reduces the apparent size of distant taxa, rendering the images unusable for quantitative analysis of reef conditions. Here we solve this century-long distortion problem by developing a novel computer-vision algorithm,ReScape, which removes the perspective distortion from reefscape images by transforming them into top-down views, making them usable for quantitative analysis of reef conditions. In doing so, we demonstrate the first-ever ecological application and extension of inverse-perspective mapping—a foundational technique used in the autonomous-driving industry. TheReScapealgorithm is composed of seven functions that (1) calibrate the camera lens, (2) remove the inherent lens-induced image distortions, (3) detect the scene’s horizon line, (4) remove the camera-roll angle, (5) detect the transformable reef area, (6) detect the scene’s perspective geometry, and (7) apply brute-force inverse-perspective mapping. The performance of theReScapealgorithm was evaluated by transforming the perspective of 125 reefscape images. Eighty-five percent of the images had no processing errors and of those, 95% were successfully transformed into top-down views.ReScapewas validated by demonstrating that same-length transects, placed increasingly further from the camera, became the same length after transformation. The mission of theReScapealgorithm is to (i) unlock historical information about coral-reef conditions from previously unquantified periods and localities, (ii) enable citizen scientists and recreational photographers to contribute reefscape images to the scientific process, and (iii) provide a new survey technique that can rigorously assess relatively large areas of coral reefs, and other marine and even terrestrial ecosystems, worldwide. To facilitate this mission, we compiled theReScapealgorithm into a free, user-friendly App that does not require any coding experience. Equipped with theReScapeApp, scientists can improve the management and prediction of the future of coral reefs by uncovering historical information from reefscape-image archives and by using reefscape images as a new, rapid survey method, opening a new era of coral-reef monitoring.
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- PAR ID:
- 10501078
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 14
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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