Balancing the benefits and risks of population connectivity to coral restoration in the age of emergent disease

Abstract The dispersal of propagules from restored coral populations is a critical consideration in restoration planning. However, coastal currents that disperse these propagules also have the potential to disperse disease. On Florida’s Coral Reef (FCR), stony coral tissue loss disease (SCTLD) has severely degraded coral populations, simultaneously creating a need and a challenge for restoration activities. Here we have applied biophysical simulation to identify high-value restoration locations with low disease risk. We simulated the dispersal of five species of coral larvae and the SCTLD pathogenic agent in a high-resolution coastal ocean circulation model. We then developed a restoration indicator that penalized the restoration value afforded by seeding potential by the risk of disease exposure. Simulations suggest that during this disease outbreak populations were more connected by disease than by larvae, and many locations that facilitate network connectivity of corals would also facilitate disease transmission. We’ve identified species-specific and multispecies disease-penalized restoration hotspots throughout FCR that may represent good candidates for coral outplanting, and provide scores for Mission Iconic Reefs restoration sites. Cheeca Rocks and Carysfort reefs were predicted to be exceptional multispecies restoration candidates. This study confirms that the restoration and conservation goal of promoting population connectivity becomes thorny in a time of increasing disease emergence and virulence. There are many considerations in restoration planning, and seeding potential is just one. An approach that considers disease transmission alongside population connectivity may provide better restoration outcomes.