Assessing acute thermal assays as a rapid screening tool for coral restoration

Abstract

Escalating environmental threats to coral reefs coincides with global advancements in coral restoration programs. To improve long-term efficacy, practitioners must consider incorporating genotypes resilient to ocean warming and disease while maintaining genetic diversity. Identifying such genotypes typically occurs under long-term exposures that mimic natural stressors, but these experiments can be time-consuming, costly, and introduce tank effects, hindering scalability for hundreds of nursery genotypes used for outplanting. Here, we evaluated the efficacy of the acute Coral Bleaching Automated Stress System (CBASS) against long-term exposures on the bleaching response of Acropora cervicornis, the dominant restoration species in Florida’s Coral Reef. Comparing bleaching metrics, Fv/Fm, chlorophyll, and host protein, we observed similar responses between the long-term heat and the CBASS treatment of 34.3 °C, which was also the calculated bleaching threshold. This suggests the potential of CBASS as a rapid screening tool, with 90% of restoration genotypes exhibiting similar bleaching tolerances. However, variations in acute bleaching phenotypes arose from measurement timing and experiment heat accumulation, cautioning against generalizations solely based on metrics like Fv/Fm. These findings identify the need to better refine the tools necessary to quickly and effectively screen coral restoration genotypes and determine their relative tolerance for restoration interventions.