The RRAP Rubble Stabilisation R&D Subprogram is investigating methods to stabilise damaged reef surfaces where dead or degraded corals have become loose and unconsolidated rubble, preventing or slowing reef recovery.
Natural and man-made disturbances (for example, cyclones, ship groundings, crown-of-thorns starfish outbreaks or coral bleaching) can reduce functional and diverse coral reefs to fields of rubble, with an unstable and mobile surface. The lack of stability and frequent motion inhibits recruitment (settlement and regrowth) of young corals back onto reefs and hampers recovery.
Rubble stabilisation, as a reef restoration technique, is in its infancy.
It is also important to be able to identify coral reefs that can most benefit from restoration strategies: those most vulnerable to rubble formation, and those where prevailing wave regimes can make mobile rubble persist and hinder recovery.
The initial four-year program has the following objectives:
Of interest is identifying reefs where rubble is most likely to be generated through cyclone disturbance, crown-of-thorns starfish outbreaks and/or bleaching events, each of which can generate different rubble volumes and characteristics. In addition, we will identify where the hydrodynamic conditions can maintain or continue to mobilise rubble, preventing stabilisation and thus coral settlement and recovery.
Evidence will be drawn from existing reef restoration activities to assess the effectiveness of rubble stabilisation on ecosystem recovery. While some of this information will be available from other trials, we will run an evaluation of the efficacy of at least one existing methodology under a range of physical conditions. We will also begin innovative research to explore the potential of biogeochemical binding methods as a future prospect for rubble stabilisation at larger scales than currently economically feasible.
Drawing on the above outcomes, a dedicated package of rubble stabilisation guidance tools will be produced (such as manuals, maps, and standing operating protocols) to assist reef managers to prioritise assessment of rubble stabilisation interventions and allow users to decide where stabilisation activities are likely to be both useful and feasible.
The data and outcomes of this subprogram will also be utilised by the RRAP Modelling and Decision-Support Subprograms to be integrated alongside a broader suite of ecological dynamics and alternative restoration strategies.
The project aims to determine where rubble will be a persistent problem on the Great Barrier Reef, hindering recovery of the reef after storms, bleaching or crown-of-thorns starfish predation.
This project aims to evaluate and test the efficacy of existing approaches to rubble stabilisation and explore new bio-geochemical-binding methods.
This project will not only synthesis results of RRAP rubble stabilisation research but build new rubble stabilisation modelling and analysis tools and guidelines for local practitioners.
Ceccarelli, D. M., McLeod, I. M., Boström-Einarsson, L., Bryan, S. E., Chartrand, K. M., Emslie, M. J., Gibbs, M. T., Gonzalez Rivero, M., Hein, M. Y., Heyward, A., Kenyon, T. M., Lewis, B. M., Mattocks, N., Newlands, M., Schläppy, M.-L., Suggett, D. J., & Bay, L. K. (2020). Substrate stabilisation and small structures in coral restoration: State of knowledge, and considerations for management and implementation. PLOS ONE, 15(10), e0240846. https://doi.org/10.1371/journal.pone.0240846
Lewis, B. M., Suggett, D. S., Prentis, P. J., & Nothdurft, L. D. (2022). Cellular adaptations leading to coral fragment attachment on artificial substrates in Acropora millepora (Am-CAM). Scientific Reports, 12, Article 18431. https://doi.org/10.1038/s41598-022-23134-8
Kenyon, T. M., Mumby, P. J., Callaghan, D. P., Baldock, T. E., & Doropoulos, C. (2023). Coral rubble dynamics in the Anthropocene and implications for reef recovery. Limnology and Oceanography, 68(12), 2955–2969. https://doi.org/10.1002/lno.12254
Harris, D. L., Webster, J. M., Vila-Concejo, A., Duce, S., Leon, J. X., & Hacker, J. (2023). Defining multi-scale surface roughness of a coral reef using a high-resolution LiDAR digital elevation model. Geomorphology, 439, 108852. https://doi.org/10.1016/j.geomorph.2023.108852
Kenyon, T. M., Harris, D., Baldock, T., Callaghan, D., Doropoulos, C., Webb, G., Newman, S. P., & Mumby, P. J. (2023). Mobilisation thresholds for coral rubble and consequences for windows of reef recovery. Biogeosciences, 20(20), 4339–4357. https://doi.org/10.5194/bg-20-4339-2023
Kenyon, T. M., Jones, C., Rissik, D., Brassil, W., Callaghan, D. P., Mattocks, N., & Baldock, T. E. (2025). Bio-degradable ‘reef bags’ used for rubble stabilisation and their impact on rubble stability, binding, coral recruitment and fish occupancy. Ecological Engineering, 210, 107433. https://doi.org/10.1016/j.ecoleng.2024.107433
Kenyon TM, Eigeland K, Wolfe K, et al. Material Legacies on Coral Reefs: Rubble Length and Bed Thickness Are Key Drivers of Rubble Bed Recovery. Glob Chang Biol. 2024;30(11):e17574. doi:10.1111/gcb.17574
Deng, W., Kenyon, T., Eigeland, K., Callaghan, D. P., & Baldock, T. E. (2025). Structural and hydrodynamic modelling of the probability of breakage of branching and plate coral colonies. Coastal Engineering, 195, 104647. https://doi.org/10.1016/j.coastaleng.2024.104647
Liu, D., Callaghan, D. P., Wuppukondur, A., & Baldock, T. E. (2025). A probabilistic coral rubble mechanical instability model applied with field observations from the Great Barrier Reef. Coastal Engineering, 195, 104655. https://doi.org/10.1016/j.coastaleng.2024.104655
Kenyon, T. M., Mumby, P. J., Webb, G. E., Dove, S., Newman, S. P., & Doropoulos, C. (2025). Trajectories and agents of binding in stabilized and unstabilized coral rubble across environmental gradients. Ecosphere, 16(2), e70195. https://doi.org/10.1002/ecs2.70195
Liu, D., Callaghan, D. P., & Baldock, T. E. (2025). Accelerating coral rubble instability assessments with machine learning: Insights from the Great Barrier Reef. Applied Ocean Research, 158, Article 104580. https://doi.org/10.1016/j.apor.2025.104580
Liu, D., Callaghan, D. P., & Baldock, T. E. (2025). Quantifying the impact of future climate change on the risk of coral rubble instability across the Great Barrier Reef by 2100. Journal of Environmental Management, 386, Article 125716. https://doi.org/10.1016/j.jenvman.2025.125716
Cheung, Mandy W.M., Chaloupka, Milani, Mumby, Peter J., and Callaghan, David P. (2025). The spatial risk of cyclone wave damage across the Great Barrier Reef. Ecological Informatics 89 103175 103175-89. https://doi.org/10.1016/j.ecoinf.2025.103175
Deng, W., Kenyon, T., Eigeland, K., Callaghan, D. P., & Baldock, T. E. (2025). Structural and hydrodynamic modelling of the probability of breakage of branching and plate coral colonies. Coastal Engineering, 195, 104647. https://doi.org/10.1016/j.coastaleng.2024.104647
Lewis, B., Suggett, D., Prentis, P., Cooper, C., & Nothdurft, L. (2025). Asexual reproduction in reef-building corals: insights into fragment attachment to improve restoration and predict natural recovery. Royal Society Open Science, 12(10), Article 251209. https://doi.org/10.1098/rsos.251209
Deng, W., Simonnet, C., Nolan, L., Callaghan, D. P., & Baldock, T. E. (2026). Investigating coral rubble dynamics through tilting base and flume experiments. Coastal Engineering, 205, 104931. https://doi.org/10.1016/j.coastaleng.2025.104931
Kenyon, T. M., Eigeland, K., Richardson, M. A., Baldock, T. E., Wolfe, K. D., Sjahruddin, F. F., & Mumby, P. J. (2025). Threshold velocities for coral rubble bind breakage across varying reef environments. Marine Ecology Progress Series, 773, 1–16. https://doi.org/10.3354/meps14982
Supported by the Queensland State Government Small Business Innovation Research Program.
