Improving Early Life Survival of Priority Grazers – Phase II

This work was designed to advance scalable production of two reef grazers, Diadema antillarum and Maguimithrax spinosissimus, and to maintain a living archive of the federally Endangered Atlantic pillar coral, Dendrogyra cylindrus, in support of active restoration on Florida's Coral Reef. For D. antillarum land-based production, results suggest that supplemental benthic diets developed at research scale (an initial feeding with Navicula sp. followed by a transition to flocculated Rhodomonas salina and Chaetoceros muelleri) should not be applied at the first observation of settlement, but rather delayed until a satisfactory proportion of the cohort has settled, as early application showed a potential negative effect on continued settlement success. Reduced among-vessel variance in survival in supplemented vessels indicates that standardized diets can improve production predictability by mitigating variation in naturally derived biofilm development across replicate vessels, and continued refinement of delivery methods is recommended. Offshore in situ nursery systems supported continued survivorship and growth of juvenile D. antillarum under two cage configurations evaluated, and cage partitioning may improve survival and growth during juvenile grow-out. These findings support the use of offshore nurseries as an intermediate phase between land-based aquaculture and direct reef stocking. Preliminary observations from the integrated coral-urchin experiment suggest that low to moderate urchin densities may provide grazing benefits without substantial negative impacts to co-cultured coral fragments, but continued monitoring is needed to identify optimal stocking densities. For M. spinosissimus, growth and survival data from reciprocal transfers between recirculating and flow-through seawater systems will inform a growth model predicting time to target stocking size, with details to be provided in the final report. Husbandry of all 145 D. cylindrus colonies at The Florida Aquarium continued without mortality through the project period, with a subset of 85 colonies maintained in conditions promoting post-award spawning to support genotype banking.