Coral nursery and outplanting practices have grown in popularity worldwide for targeted restoration of degraded "high value" reef sites, and recovery of threatened taxa. Success of these practices is commonly gauged from coral propagule growth and survival, which fundamentally determines the return-on-effort (RRE) critical to the cost-effectiveness and viability of restoration programs. In many cases, RRE has been optimized from past successes and failures, which therefore presents a major challenge for locations such as the Great Barrier Reef (GBR) where no local history of restoration exists to guide best practice. In establishing the first multi-taxa coral nursery on the GBR (Opal Reef, February 2018), we constructed a novel scoring criterion from concurrent measurements of growth and survivorship to guide our relative RRE, including nursery propagule numbers (stock density). We initially retrieved RRE scores from a database of global restoration efforts to date (n = 246; 52 studies) to evaluate whether and how success commonly varied among coral taxa. We then retrieved RRE scores for Opal Reef using initial growth and survivorship data for six key coral taxa, to demonstrate that RRE scores were high for all taxa predominantly via high survivorship over winter. Repeated RRE scoring in summer is therefore needed to capture the full dynamic range of success where seasonal factors regulating growth versus survivorship differ. We discuss how RRE scoring can be easily adopted across restoration practices globally to standardize and benchmark success, but also as a tool to aid decision-making in optimizing future propagation (and outplanting) efforts.

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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.

Global threats to reefs require urgent efforts to resolve coral attributes that affect survival in a changing environment. Genetically different individuals of the same coral species are known to exhibit different responses to the same environmental conditions. New information on coral physiology, particularly as it relates to genotype, could aid in unraveling mechanisms that facilitate coral survival in the face of stressors. Metabolomic profiling detects a large subset of metabolites in an organism, and, when linked to metabolic pathways, can provide a snapshot of an organism’s physiological state. Identifying metabolites associated with desirable, genotype-specific traits could improve coral selection for restoration and other interventions. A key step toward this goal is determining whether intraspecific variation in coral metabolite profiles can be detected for species of interest, however little information exists to illustrate such differences. To address this gap, we applied untargeted 1 H-NMR and LC-MS metabolomic profiling to three genotypes of the threatened coral Acropora cervicornis . Both methods revealed distinct metabolite “fingerprints” for each genotype examined. A number of metabolites driving separation among genotypes were identified or putatively annotated. Pathway analysis suggested differences in protein synthesis among genotypes. For the first time, these data illustrate intraspecific variation in metabolomic profiles for corals in a common garden. Our results contribute to the growing body of work on coral metabolomics and suggest future work could identify specific links between phenotype and metabolite profile in corals.

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