Environmental drivers of recruitment success in Caribbean corals: Applications to aid the recovery of threatened coral populations

Caribbean coral reefs are amongst the most threatened marine ecosystems on Earth. About one third of their reef-building coral species (Scleractinia) are currently at risk of extinction due to habitat destruction, overexploitation and climate change. The successful establishment of coral larvae, also known as larval recruitment, is a pivotal process determining the long-term survival of coral populations. Under suitable conditions, adult corals can produce thousands of larvae that contribute to the replenishment of coral populations and to the maintenance of genetic variation in these populations. Along with the decline of adult Caribbean coral communities, however, the abundance of coral recruits decreased dramatically over the past three decades. This thesis aimed to gain a better understanding of the environmental processes affecting larval recruitment in Caribbean corals, with a particular focus on identifying the conditions under which recruitment will be successful. This was investigated through a series of observational studies and manipulative experiments in the laboratory and under natural conditions. Findings collected during these studies were then used to optimize restoration efforts aimed at increasing larval recruitment in threatened coral communities. For instance, we developed a new seeding approach in which coral larvae are reared in the laboratory and settled on artificial substrates, which are then sown out over the reef. This thesis has shown how studies on coral species’ reproductive biology and early life ecology provide invaluable insights on the factors contributing to their successful recruitment, and demonstrates that such findings can be used to assist the recovery of imperiled coral species