Microfragmenting for the successful restoration of slow growing massive corals

Slow growing, massive stony corals have often been overlooked in reef-restoration activities, despite their resilience to climate change and contribution to reef framework. Techniques to effectively propagate and outplant these species have proven challenging. However, advancement in methodology may increase rates of success. In 2013, Orbicella faveolata and Montastrea cavernosa fragments were outplanted on reefs in the Florida Keys at a nearshore and offshore location, to determine whether “microfragmenting” corals, the process of creating ∼1 cm2 fragments, increased outplant survival and growth compared with larger fragments (16–64 cm2). Arrays of eight microfragments were planted near one larger fragment of similar size at each location. Six replicate pairs were haphazardly placed within each ∼700 m2 study site. Fragments at both sites were monitored for growth and survival over 31 months, spanning two bleaching events. Initial predation occurred on microfragments, but was absent in the larger fragments. Survival and growth differed between sites, but did not differ between the larger fragments and microfragment arrays. However, excluding plots with >40% predation at the nearshore site showed that O. faveolata microfragment arrays produced 10 times more tissue than traditionally used larger fragments. Results from this study suggest that if predation events are reduced, massive corals can be successfully grown and outplanted for restoration purposes.