Early life stages of stress-tolerant corals (Favites spp.) exhibit tolerance to acute thermal stress.

The Bolinao-Anda Reef Complex (BARC) in northwestern Philippines is one of the most heavily impacted reef systems in the Philippines, experiencing recurring marine heat waves and declining water quality due to coastal development and mariculture. As ocean warming and declining water quality continue, stress-tolerant coral species are expected to become increasingly dominant. Understanding how these corals respond to elevated temperatures in the early stages is critical for predicting future reef trajectories. In this study, we examined survival and development of embryos, settlement and survival of larvae, and survival of recruits of the stress-tolerant corals Favites abdita and Favites colemani collected from BARC under control (28°C) and elevated (33-35°C) temperatures. In both species, elevated temperature did not significantly affect embryo survival and development, larval survival and settlement, or recruit survival. Results show that early stages of Favites development can tolerate temperatures ranging from 28 to 35°C. These findings support the classification of Favites spp. as stress-tolerant corals capable of persisting in BARC despite repeated thermal anomalies. While early life stages exhibited short-term thermal tolerance, further research is needed to determine whether thermally exposed recruits experience long-term physiological or ecological trade-offs.