Reported and Reassessed Outcomes of Coral Reef Restoration in the Philippines

Baquiran, Ethel Ruth A.

Ecosystem restoration is a key nature-based solution for climate change adaptation, biodiversity loss, and food insecurity. However, the extent at which coral reef restoration (CRR) has aided Philippine reef recovery remains unreported. I addressed this gap through a systematic review, a field reassessment of restored sites in the Bolinao-Anda Reef Complex (BARC) using metrics aligned with an Evaluation Tool, and a comparison with nearby unrestored sites using the Point-Intercept-Transect method. My systematic review reveals that the genus Acropora and the species Porites cylindrica were the most reported. Asexual propagation was the predominant method across all data sources, with a median percent survival of 75%. Restoration amounted to ~160,000 USD per hectare and outcomes were typically reported after 1.25 years of monitoring. Only four of eleven revisited studies retained more than two living outplants after nearly two decades. Evaluation of four reassessed studies mirrors nationwide trends in reporting outcomes: survival and growth are well-documented, while partial mortality and total restored area were not. Survival declined to below 50% for competitive Acropora tenuis and weedy Porites cylindrica while stress-tolerant Favites abdita maintained a ~70% survival among the four coral species after 13 years. Marine heatwaves (MHW) in BARC have doubled in frequency in the last 18 years compared to records from 1982 to 2000. Both coral life histories, site characteristics, and local marine resource management allowed coral populations in restored and unrestored sites to persist. Social and ecological diversity in future CRR initiatives may prolong reef-to colony-level outcomes.