Coral Propagation: Land-based and Offshore Nursery Phase II

The purpose of this project was to propagate the coral species that were most impacted by the disease outbreak, Montastraea cavernosa, Orbicella faveolata, Pseudodiploria clivosa, P. strigosa, and Colpophyllia natans using sexual and asexual reproduction modes. This will allow us to increase the live coral biomass available for future restoration projects, preserve the genetic diversity of the corals that survived the disease (potentially more disease resistant), and increase the genetic diversity of the populations on the reef (new genotypes are formed through genetic recombination). 

Our assessment of coral fecundity through histology revealed that most corals in field in Broward County are reproductive; about 67% of the P. clivosa and nearly all O. faveolata were fecund. M. cavernosa colonies held in an indoor recirculating system for the past year spawned synchronously when their temperature, and (moon and sun) light cycles were manipulated, with spawning occurring mostly in August 2020. Larvae of all coral species successfully settled on tiles conditioned for two months in the indoor recirculating system, and sprinkled with (crushed) crustose coralline algae. For the land-based nursery, the training of staff, optimization of light levels and improved food led to higher survival and growth rates than observed in previous years at this facility. For the offshore nursery, survival of the 6-months sexual recruits was lower than in the land-based nursery, as expected; however, predation did not appear to be very high. Our results also suggest that while the grow-out of massive corals through processes of microfragmentation in offshore nurseries is in its infancy, it appears to be very successful.