Cost-efficiency and effectiveness of coral restoration pathways

Coral reefs play a crucial role in supporting over half a billion human livelihoods through their contributions to fisheries, tourism, and coastal protection. In light of substantial global declines in coral cover and the deterioration of reef habitats due to climate change and other human-driven influences, the urgency of coral reef restoration has escalated to help preserve their vital ecosystem services. Comprehending the economic costs associated with existing and potential future coral restoration approaches has become time-sensitive. The median cost of coral reef restoration is estimated to be 400,000 USD/ha (at base year 2010). This estimate comes with limitations due to its reliance on reported project costs associated with various techniques. Here we look to standardize expenses through uniform costing of reported efforts based on the time invested to estimate specific per-unit costs for restoration methods. We complement literature-extracted values with independent estimates based on real-world operations. Using this approach, we decipher comparative costs of different nursery and outplanting approaches and identify incorporated dependencies. To gain insights into the impact of labor costs on global coral reef restoration expenditures, we examine variations in the costs of labor in two coral reef regions. Overall, our data-based approach identifies limitations within the most commonly practiced restoration pathways, opportunities to reduce operational costs, and points toward priorities for future research and development.