Evaluation of ROV-Based Coral Reef Monitoring System: A Comparative Analysis with Underwater Photo Transect in Nabire Waters, Cenderawasih Bay National Park, Indonesia

Nicodemus Rahanra (Universitas Papua)
Abdul Hamid Toha (Universitas Papua)
Paulus Boli (Universitas Papua)
Selvi Tebay (Universitas Papua)

Majority Science Journal
Vol. 4 No. 3 (2026): MSJ - August

Background: Coral reef monitoring in tropical archipelago regions faces persistent challenges including limited diver availability, high operational costs, and safety risks. Remotely Operated Vehicles (ROV) have emerged as a promising technological alternative, yet systematic evaluation of their accuracy and efficiency relative to established quantitative methods remains limited, particularly in Indonesian waters. Methods: A parallel comparative survey was conducted on 6 January 2025 at Nusi Island, Cenderawasih Bay National Park, Nabire, Papua Province, Indonesia. Two stations (Nusi 1 and Nusi 2) were monitored simultaneously using Underwater Photo Transect (UPT) analysed with Coral Point Count with Excel extensions (CPCe) software and a Gladius Mini ROV (MORAL-BOT system). Each UPT station generated ~1,500 random-point classifications from 50 photographic frames along a 50-m transect. Relative deviation analysis and descriptive statistics (Shapiro-Wilk, Mann-Whitney U, Cohen’s d effect size) were applied to compare methodological performance. Cost and time efficiency were assessed using activity-based costing and time-motion study. Results: UPT-CPCe detected live hard-coral cover (HC) of 29.89% at Nusi 1 (Moderate category) and 3.13% at Nusi 2 (Poor category), with a statistically significant difference (Mann-Whitney U, p < 0.05; Cohen’s d = 1.008, large effect size). ROV estimated HC < 5% at both stations. Mean relative deviation between methods was 87.8% at Nusi 1 (patchy habitat) and 13.1% at Nusi 2 (homogeneous degraded habitat). ROV surveys were completed 3.8× faster (55 min vs. 210 min) and at 83% lower operational cost (Rp 2,100,000 vs. Rp 12,500,000) compared with UPT. Conclusions: UPT-CPCe outperforms ROV in quantitative precision and taxonomic resolution, especially in heterogeneous reef habitats. Conversely, ROV provides significant advantages in operational efficiency, safety, and the ability to access greater depths. A hybrid monitoring protocol—ROV for rapid spatial coverage and UPT for quantitative baseline validation—is recommended as the optimal approach for large-scale, cost-effective reef monitoring in Indonesia’s eastern archipelago.