How Much Shallow Coral Habitat Is There on the Great Barrier Reef?

Roelfsema, Chris M., Lyons, Mitchell B., Castro-Sanguino, Carolina, Kovacs, Eva M., Callaghan, David, Wettle, Magnus, Markey, Kathryn, Borrego-Acevedo, Rodney, Tudman, Paul, Roe, Meredith, Kennedy, Emma V., Gonzalez-Rivero, Manuel, Murray, Nicholas, and Phinn, Stuart R. (2021) How Much Shallow Coral Habitat Is There on the Great Barrier Reef? Remote Sensing, 13 (21). 4343.

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Australia’s Great Barrier Reef (GBR) is a globally unique and precious national resource; however, the geomorphic and benthic composition and the extent of coral habitat per reef are greatly understudied. However, this is critical to understand the spatial extent of disturbance impacts and recovery potential. This study characterizes and quantifies coral habitat based on depth, geomorphic and benthic composition maps of more than 2164 shallow offshore GBR reefs. The mapping approach combined a Sentinel-2 satellite surface reflectance image mosaic and derived depth, wave climate, reef slope and field data in a random-forest machine learning and object-based protocol. Area calculations, for the first time, incorporated the 3D characteristic of the reef surface above 20 m. Geomorphic zonation maps (0–20 m) provided a reef extent estimate of 28,261 km2 (a 31% increase to current estimates), while benthic composition maps (0–10 m) estimated that ~10,600 km2 of reef area (~57% of shallow offshore reef area) was covered by hard substrate suitable for coral growth, the first estimate of potential coral habitat based on substrate availability. Our high-resolution maps provide valuable information for future monitoring and ecological modeling studies and constitute key tools for supporting the management, conservation and restoration efforts of the GBR.

Item ID: 73315
Item Type: Article (Research - C1)
ISSN: 2072-4292
Keywords: Benthic, Coral reef, Geomorphic, Great Barrier Reef, Habitat map, Sentinel-2
Copyright Information: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Date Deposited: 10 May 2022 22:23
FoR Codes: 37 EARTH SCIENCES > 3709 Physical geography and environmental geoscience > 370999 Physical geography and environmental geoscience not elsewhere classified @ 40%
41 ENVIRONMENTAL SCIENCES > 4102 Ecological applications > 410206 Landscape ecology @ 20%
37 EARTH SCIENCES > 3704 Geoinformatics > 370499 Geoinformatics not elsewhere classified @ 40%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1805 Marine systems and management > 180501 Assessment and management of benthic marine ecosystems @ 100%
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