Abstract
The rapid decline of coral reefs has made optimizing ex-situ coral growth rates and developing restoration and outplanting strategies essential for the long-term survival of reef ecosystems. This study evaluates whether continuous calcium hydroxide dosing in a controlled flow-through environment will enhance pH and alkalinity to optimize ex-situ coral propagation. Because coral calcification is strongly influenced by pH and alkalinity, elevated parameters are hypothesized to reduce the energetic cost of skeletal deposition, promoting faster growth. This study used two species of commonly propagated coral, Orbicella faveolata (OFAV) and Diploria labyrinthiformis (DLAB), with two genotypes of each species. We found that, with continuous dosing even in a constant flow-through system, both alkalinity and pH of the systems were significantly increased. While the short timeframe of the experiment limited its ability to detect changes in coral growth, positive trends in relation to increased pH were still documented. The findings from this study will be used to inform and optimize ex-situ coral propagation procedures to enhance coral growth and coral restoration efforts.