Long‐term survival and colony growth of Acropora palmata fragments transplanted by volunteers for restoration

Many branching corals are fragmented by storms, which can serve as a mechanism of asexual reproduction for species that are able to reattach themselves to the substratum and form new colonies. Fragments can also be manually reattached as a means of reef restoration. The growth and survival of 832 fragments of Elkhorn coral, Acropora palmata, that were transplanted for a restoration project in the British Virgin Islands was modelled. Mortality was higher in the first year after transplanting than in subsequent years, perhaps reflecting stress from handling or failure of the attachment method. Survival also varied with the year of transplantation (from 2005–2011), and was lowest in years with major storms (2007 and 2010). Fragment survival increased with increasing initial size, with the largest fragments (surface area roughly 1000 cm²) faring substantially better than the smallest (roughly 10 cm²) and average sized fragments (roughly 100 cm²). Colony size (surface area of live tissue) tended to decrease slightly in the first 3 months after being reattached, presumably due to stress from transplanting. Subsequently, the surface area of surviving colonies tended to progressively increase over time, with fragments typically reaching 3000 cm² after 7 years. Colony growth was, however, extremely variable and largely independent of initial colony size. Despite initial reductions in growth and survival due to transplanting, long‐term survival of transplanted fragments was roughly comparable with that of natural colonies. Transplanting fragments is thus a promising tool for grass‐roots restoration projects. Copyright © 2013 John Wiley & Sons, Ltd.