Coral-spawn slicks: Reflectance spectra and detection using optical satellite data

This study provides the first report of reflectance spectra of coral-spawn slicks and their detection using optical satellite data. The reflectance spectra show that coral-spawn slicks can be discriminated from other sea-surface features such as wave foam and floating Sargassum. Analysis of Planet D...

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Bibliographic Details
Published in:Remote sensing of environment 2020-12, Vol.251, p.112058, Article 112058
Main Authors: Yamano, Hiroya, Sakuma, Asahi, Harii, Saki
Format: Article
Language:English
Subjects:
Coral bleaching
Coral bundle
Coral mass spawning
Coral-spawn slick
Foams
Planet Dove
Reflectance
Satellite constellation
Satellite constellations
Satellite data
Satellite observation
Satellites
Sentinel-2
Slicks
Spatial discrimination
Spatial resolution
Spawning
Spectra
Temporal resolution
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Summary:This study provides the first report of reflectance spectra of coral-spawn slicks and their detection using optical satellite data. The reflectance spectra show that coral-spawn slicks can be discriminated from other sea-surface features such as wave foam and floating Sargassum. Analysis of Planet Dove and Sentinel-2B imagery allowed successful detection of coral-spawn slicks at Ishigaki Island, Okinawa, Japan (24°31′40″N, 124°17′31″E), by using reflectance values in the green and red wavelength regions. This detection was attributable to both their high spatial resolution (3.7 m and 10 m, respectively) and high temporal resolution (1 day and 5 days, respectively), given that coral spawning occurs within a short period (up to several days), typically once a year, and that the coral-spawn slicks have narrow widths of ~10 m. The number of the detected coral-spawn slicks was small, possibly because of coral decline around Ishigaki Island caused by the 2016 worldwide mass coral bleaching event. High-frequency satellite observations, including those from satellite constellations, should provide a powerful tool for understanding coral-reef processes and features whose detection requires high spatial and temporal resolution. •First report of reflectance spectra of coral-spawn slicks and their detection.•The reflectance spectra can be discriminated from other sea-surface features.•Satellite constellations allowed observation after a coral mass spawning event.•The red/green band ratio detected coral-spawn slicks successfully.•Detected slicks were small, possibly because of the 2016 coral bleaching event.
ISSN:0034-4257
1879-0704
DOI:10.1016/j.rse.2020.112058