The threatened status (both ecologically and legally) of Caribbean staghorn coral, Acropora cervicornis, has prompted rapidly expanding efforts in culture and restocking, although tissue loss diseases continue to affect populations. In this study, disease surveillance and histopathological characterization were used to compare disease dynamics and conditions in both restored and extant wild populations. Disease had devastating effects on both wild and restored populations, but dynamics were highly variable and appeared to be site-specific with no significant differences in disease prevalence between wild versus restored sites. A subset of 20 haphazardly selected colonies at each site observed over a four-month period revealed widely varying disease incidence, although not between restored and wild sites, and a case fatality rate of 8%. A tropical storm was the only discernable environmental trigger associated with a consistent spike in incidence across all sites. Lastly, two field mitigation techniques, (1) excision of apparently healthy branch tips from a diseased colony, and (2) placement of a band of epoxy fully enclosing the diseased margin, gave equivocal results with no significant benefit detected for either treatment compared to controls. Tissue condition of associated samples was fair to very poor; unsuccessful mitigation treatment samples had severe degeneration of mesenterial filament cnidoglandular bands. Polyp mucocytes in all samples were infected with suspect rickettsia-like organisms; however, no bacterial aggregates were found. No histological differences were found between disease lesions with gross signs fitting literature descriptions of white-band disease (WBD) and rapid tissue loss (RTL). Overall, our results do not support differing disease quality, quantity, dynamics, nor health management strategies between restored and wild colonies of A. cervicornis in the Florida Keys.

In the current era of reduced coral populations, the effects of predation are likely to compromise the growing investment in restocking of imperiled coral populations and may be a strong, chronic deterrent of natural population recovery. A 2 yr surveillance study documented highly variable prevalence of predation by the fireworm Hermodice carunculata on both wild (0 to 51%) and restocked (0 to 53%) populations of the Caribbean staghorn coral Acropora cervicornis, but significantly higher prevalence overall in 2012 than 2011. In addition, individual predation scars (branch tips) were tagged to determine the costs of predation both in terms of healing time (i.e. to recover positive rates of branch growth) and in terms of likelihood of progressive diseaselike tissue loss on preyed branch tips. The risk of preyed branches showing progressive tissue loss at the subsequent survey was 10 times higher than for non-preyed branches. A survival analysis indicated an estimated mean time to healing for preyed branch tips of 110 ± 6 d (95% confidence). Finally, an experiment conducted in 2013 tested whether removing the dead skeleton from preyed branch tips could accelerate recovery. Indeed, this intervention shortened the mean time to formation of a new apical tip to 46 d (range: 22 to 92 d). Thus, fireworm predation imposes significant costs on both remnant wild and restocked staghorn colonies, but removing dead tips, rather than leaving them to bioerode, is a useful strategy to accelerate recovery from predation.

18The threatened status (both ecologically and legally) of Caribbean staghorn coral, Acropora 19 cervicornis, has prompted rapidly expanding efforts in culture and restocking, although tissue 20 loss diseases continue to affect populations. In this study, disease surveillance and 21 histopathological characterization were used to compare disease dynamics and conditions in both 22 restored and extant wild populations. Disease had devastating effects on both wild and restored 23 populations, but dynamics were highly variable and appeared to be site-specific with no 24 significant differences in disease prevalence between wild versus restored sites. Disease affected 25 up to 80% of colonies at one site following a tropical storm. A subset of 20 haphazardly selected 26 colonies at each site observed over a single field season revealed widely varying disease 27 incidence, although not in a consistent way between restored and wild sites, and a case fatality 28 rate of 8%. Lastly, two field mitigation techniques, (1) excision of apparently healthy branch 29 tips from a diseased colony, and (2) placement of a band of epoxy fully enclosing the diseased 30 margin, gave equivocal results with no significant benefit detected for either treatment compared 31 to controls. Tissue condition of associated samples was fair to very poor; unsuccessful 32 mitigation treatment samples had severe degeneration of mesenterial filament cnidoglandular 33 bands. Polyp mucocytes in all samples were infected with suspect rickettsia-like organisms; no 34 bacterial aggregates were found. Overall results do not support differing disease quality, 35 quantity, dynamics, or health management strategies between restored and wild colonies of A. 36 cervicornis in the Florida Keys. 37 38PeerJ PrePrints | http://dx.doi.org/10.7287/peerj.preprints.328v1 | CC-BY 4.0