A Comparative Analysis of Coral Reef Degradation in Nabire Bay, Indonesia, Using ROV-Based Quantitative Assessment: A Tale of Two Sites

Coastal marine ecosystems in the Coral Triangle are facing unprecedented threats, yet high-resolution data to guide management remains scarce. This study presents a comparative analysis of coral reef health at two contrasting sites in Nabire Bay, Indonesia, using quantitative data from a Remotely Operated Vehicle (ROV). Site 1 (Nabire) and Site 2 (Pulau Nusi) were surveyed to assess benthic composition. The results reveal a stark picture of degradation at both locations, but driven by different ecological dynamics. Site 2 (Pulau Nusi) is in a critical state, with live coral cover at a mere 3.13% and dominated by sand (61.73%) and rubble (21.20%), indicating chronic sedimentation stress. Site 1 (Nabire) shows slightly better but still poor conditions, with live coral cover at 6.64%, but with a higher proportion of dead coral (17.27%). The comparative analysis highlights that while both sites are severely degraded, the dominant degradation driver at Pulau Nusi is likely terrestrial runoff and sedimentation, whereas Site 1 may be experiencing a combination of stressors including a recent mass mortality event. This study underscores the utility of ROV technology for rapid, cost-effective, and quantitative assessment, providing crucial, site-specific data needed to develop targeted conservation and management strategies in a high-priority marine biodiversity region.

1. Ardianor, Supandi, S., Saputra, Y. H. E., Asmawi, S., Yunandar, Y., Sofarini, D., Gunawan, M. A., Handayani, T., Ardani, B., Purnaningsih, T., & Khasanah, R. (2025). Comparative assessment of marine pollution in coral reef sites of South Kalimantan across dry and rainy seasons. Egyptian Journal of Aquatic Biology and Fisheries. https://doi.org/10.21608/ejabf.2025.438038.6915
2. Bruno, J. F., et al. (2007). Thermal stress and coral cover as drivers of coral disease outbreaks. PLoS Biology, 5(6), e124.
3. Burke, L., Reytar, K., Spalding, M., & Perry, A. (2011). Reefs at Risk Revisited. World Resources Institute.
4. De Jong, C., Van Os, I., Sepúlveda-Rodríguez, G., De Baat, M., & Schoepf, V. (2025). High-resolution temporal assessment of physicochemical variability and water quality in tropical semi-enclosed bays and coral reefs. Science of the Total Environment, 968, Article 178810. https://doi.org/10.1016/j.scitotenv.2025.178810
5. Fabricius, K. E. (2005). Effects of terrestrial runoff on the ecology of corals and coral reefs: review and synthesis. Marine Pollution Bulletin, 50(2), 125-146.
6. Friedman, A., et al. (2012). A new era for coral reef science: the advent of cost-effective and autonomous underwater robotic imaging. Journal of Experimental Marine Biology and Ecology, 424, 1-7.
7. Gilmour, J., Cook, K., Ryan, N., Puotinen, M., Green, R., & Heyward, A. (2021). A tale of two reef systems: Local conditions, disturbances, coral life histories, and the climate catastrophe. Ecological Applications. Advance online publication. https://doi.org/10.1002/eap.2509
8. Ginting, S. (2023). Limitations of Conventional Diving Methods in Marine Research. Indonesian Journal of Maritime Studies, 25(1), 1-10.
9. Hadi, T. A., et al. (2019). Status Terumbu Karang Indonesia 2019. Pusat Penelitian Oseanografi LIPI.
10. Hoegh-Guldberg, O., Mumby, P. J., Hooten, A. J., Steneck, R. S., Greenfield, P., Gomez, E., Harvell, C. D., Sale, P. F., Edwards, A. J., Caldeira, K., Knowlton, N., Eakin, C. M., Iglesias-Prieto, R., Muthiga, N., Bradbury, R. H., Dubi, A., & Hatziolos, M. E. (2007). Coral reefs under rapid climate change and ocean acidification. Science, 318(5857), 1737-1742.
11. Kohler, K. E., & Gill, S. M. (2006). Coral Point Count with Excel extensions (CPCe): A Visual Basic program for the determination of coral and substrate coverage using random point count methodology. Computers & Geosciences, 32(9), 1259-1269.
12. Mumby, P. J., & Steneck, R. S. (2008). Coral reef management and conservation in light of rapidly evolving ecological paradigms. Trends in Ecology & Evolution, 23(10), 555-563.
13. Obura, D. O., & Grimsditch, G. (2009). Resilience Assessment of Coral Reefs-Assessment Protocol for Coral Reefs, focusing on coral bleaching and thermal stress. IUCN.
14. Paterson, I., Dawson, K. E., Mogg, A., Sayer, M., & Burdett, H. (2024). Quantitative comparison of ROV and diver-based photogrammetry to reconstruct maerl bed ecosystems. Aquatic Conservation: Marine and Freshwater Ecosystems. Advance online publication. https://doi.org/10.1002/aqc.70007
15. Rogers, C. S. (1990). Responses of coral reefs and reef organisms to sedimentation. Marine Ecology Progress Series, 62, 185-202.
16. Saputra, R. A. (2024). Enhancing coral reef restoration assessment using machine learning in Gili Asahan and Kecinan Bay, Lombok, Indonesia. https://doi.org/10.18258/69839