Characterizing the spatial distribution of coral reefs in the South-Central Coast region of Viet Nam using Planetscope imagery

Khanh V Nguyen; Vinh C Duong; Kinh T Kieu; Thuong V Tran; Cho-Ying Huang; Ruth Reef; Thien M Hoang

doi:10.7717/peerj.12413

Characterizing the spatial distribution of coral reefs in the South-Central Coast region of Viet Nam using Planetscope imagery

PeerJ. 2021 Nov 2:9:e12413. doi: 10.7717/peerj.12413. eCollection 2021.

Authors

Khanh V Nguyen¹, Vinh C Duong², Kinh T Kieu¹, Thuong V Tran³, Cho-Ying Huang⁴, Ruth Reef⁵, Thien M Hoang¹

Affiliations

¹ Faculty of Biology and Environment, The University of Danang-University of Science and Education, Danang City, Viet Nam.
² Department of Environment and Natural Recourses, Gia Lai Campus, Nong Lam University - Ho Chi Minh, Pleiku city, Gia Lai Province, Viet Nam.
³ Institute of Engineering and Technology, Thu Dau Mot University, Thu Dau Mot city, Binh Duong Province, Viet Nam.
⁴ Department of Geography, National Taiwan University, Taipei, Taiwan.
⁵ School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria, Australia.

Abstract

This study aims to understand the spatial distribution of coral reefs in the central region of Viet Nam. We classified live coral cover in Son Tra Peninsula (ST) and Cu Lao Cham Island (CLC) in the South-Central Coast Region of Viet Nam using the Maximum Likelihood Classifier on 3 m Planetscope imagery. Confusion matrices and the accuracy of the classifier were assessed using field data (1,543 and 1,560 photographs in ST and CLC, respectively). The results showed that the reef's width ranged from 30 to 300 m across the study site, and we were able to detect live coral cover across a depth gradient of 2 to 6 m below the sea surface. The overall accuracies of the classifier (the Kappa coefficient) were 76.78% (0.76) and 78.08% (0.78) for ST and CLC, respectively. We found that 60.25% of coral reefs in ST were unhealthy and the live coral cover was less than 50%, while 25.75% and 11.46% of those in CLC were in good and excellent conditions, respectively. This study demonstrates the feasibility of utilizing Planetscope imagery to monitor shallow coral reefs of small islands at a high spatial resolution of 3 m. The results of this study provide valuable information for coral reef protection and conservation.

Keywords: Coral health; Coral reef management and protection; Cu Lao Cham Island; Dove satellite; Live coral cover; Shallow fringing reefs; Son Tra Peninsula; Supervised classification.

Grants and funding

This research was funded by the Ministry of Education and Training, grant number B2019-DNA-04 under the project “Applying GIS and remote sensing to understand coral reef conservation in the South Central, Viet Nam”. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.