UC San Diego

Coral reefs, vital ecosystems supporting marine biodiversity, face unprecedented threats from anthropogenic climate change. The resulting reef degradation necessitates urgent restoration research. While conventional methods have focused on fragmentation, the potential of coral micropropagates for restoration remains unexplored. Polyp bailout, where polyps detach in response to acute stress, offers a promising source of micropropagates. This study pursues two objectives: 1) developing a hypersalinity-induced bailout protocol and 2) assessing micropropagate attachment to common restoration substrates. Specifically, this study tests the viability of micropropagates following hypersalinity stress using chlorophyll a fluorimetry and morphological characterization. Following successful micropropagate development, attachment and growth are observed over 14 days on CaCO3, PVC, and cement. A salinity gradient of approximately 1 ppt/hr induced bailout for Stylophora pistillata, producing micropropagates characterized by healthy morphology and average FV/FM values of 0.45 +/- 0.04. Micropropagates attachment was highest on CaCO3 (73.81% +/- 10.75%) surpassing PVC (47.62% +/- 11.66%) and cement (4.76% +/- 7.38%). Post-settlement, micropropagates displayed varying growth rates, with PVC (0.057 +/- 0.008 mm²/day) exhibiting the highest growth rate, followed by CaCO3 (0.037 +/- 0.002 mm²/day), and cement (-0.0068 +/- 0.008 mm²/day). These results show that viable S. pistillata micropropagates can be produced via hypersalinity stress in a reproducible manner and that artificial substrates made from CaCo3 produce successful attachment and healthy lateral tissue growth. Together, these findings suggest that polyp bailout has potential as a technique for generating micropropagates for coral restoration.