Impacts of Climate Change on Site Selection for Coral Restoration

Coral reefs are predicted to decline by 70-90% in the next 20 years due to bleaching from global warming of 1.5°C in addition to several other anthropogenic impacts. To combat this, coral restoration initiatives can boost the recovery of degraded reefs by increasing live coral coverage. Despite these efforts, transplanted corals often face low survival rates due to poor planning and site selection based on convenience and need for mitigation rather than likelihood and suitability for coral survival. Anthropogenic and environmental factors such as excessive nutrient input, warming waters, and unexpected wave action from storms compound existing climate-based vulnerabilities causing restoration projects to fail. As climate change increases sea surface temperature (SST) and ocean acidification, primary drivers of coral bleaching, it is critical to locate ideal restoration sites that maximize chances of survivorship - characterized by low change in SST, low change in pH, low wave energy, low eutrophication and disturbance from human impact. This study examines site selection in future climate scenarios for the successful establishment of coral transplants in tropical regions as well as globally. Potential sites are assessed for their restoration suitability by accounting for projected environmental characteristics and proxies for human impact through a regression analysis. Given current restoration standards and practices, this model finds that there are few to no suitable sites by the year 2100. It is imperative to include suitability analysis in the design of future projects to enhance the potential for successful restoration and maximize efficiency by focusing resources on promising sites. These findings contribute to ongoing work of evaluating restoration protocols and can inform necessary modifications to restoration practices as well as increasing efforts to decrease CO2 emissions to prevent the loss of coral reefs. Identifying more suitable sites in a higher atmospheric CO2 future will assist in the effectiveness of current programs and the likelihood for successful restoration efforts.