Evaluating coral propagation outcomes and costs in a monsoon-dominated reef

Full text: Evaluating coral propagation outcomes and costs in a monsoon-dominated reef environment | Coral Reefs

The global decline in tropical hard coral cover has intensified efforts and investments in reef restoration. Despite advancements in restoration methodologies, long-term data on restoration outcomes and costs remain limited in many regions, restricting effective decision-making and large-scale implementation. Therefore, this study evaluates the survival, growth, and planting cost of 250 coral propagules from six branching hard coral species over a ~ 3-year monitoring period. Corals were propagated across a fringing reef in northeastern Peninsular Malaysia, a region subject to strong annual northeast monsoon conditions. Using Coralclip®, propagules were outplanted following a 414-day nursery phase, allowing comparisons of survival and growth rates between nursery-reared corals and their outplanted counterparts to assess the predictive value of nursery performance. Survival rates over the 1085-day monitoring period varied significantly among species (2.9–47.7%), as did specific growth rates (0.05–0.22% growth day⁻¹), leading to species-specific realized planting costs (PC_R) ranging from $12.06 to $248.08 per coral. While nursery growth rates were generally predictive of post-outplanting growth for five of the six species, survival rates of propagules were markedly lower. However, Coralclip® efficiently secured propagules until they self-attached, and monsoon conditions did not disproportionately affect propagule survival, but overall low survival and high planting costs highlight the need to optimize restoration strategies in monsoon-exposed reef environments. Ultimately, these findings provide critical insights for improving cost efficiency and the long-term outcomes of coral restoration efforts in this region