Abstract Summary
The severe loss of hard coral cover over the past 30 years has prompted an interest in reef restoration by transplanting coral fragments. However, not all coral transplants are equally successful and the ecological conditions necessary for transplant resiliency in the face of disturbances are not well understood. To address this lack of knowledge, we combined a long-term reef community census with a longitudinal study of coral transplant survival on fifteen reefs in the middle Florida Keys. A total of 276 coral fragments of five species were transplanted along permanent transects and photographed quarterly from June 2013 to June 2018. During this period, two species of coral transplants were exposed to two acute thermal stress events (2014, 2015) and four species endured a category four hurricane (2017). In general, Siderastrea siderea showed higher resiliency to bleaching compared to Porites asteroides. Of all the abiotic and biotic factors measured, the amount of Dictyota spp. algae present was the factor that best explained individual variance in the propensity for bleaching. Porites asteroides, Siderastrea radians, and Orbicella faveolata had the highest survival after a physical disturbance with more than 50% of transplants surviving. Acropora cervicornis transplants were most susceptible to physical disturbance with only 16% survival. The complexity of the reef directly surrounding the coral transplant influenced the survival of A. cervicornis and O. faveolata corals, but not P. asteroides or S. radians transplants. Local topography and species composition rather than regional characteristics, such as depth, distance to shore, and visibility, explained more variation in coral resiliency. These results suggest some species are more resilient to thermal stress while others are more resilient to physical disturbance and local conditions may be the best predictors of transplant success.
