Search

Coral restoration efforts have rapidly increased worldwide, including the development of several programmes on the Great Barrier Reef (GBR) in recent years. While many restoration programmes utilise in-water nurseries to accelerate coral biomass yields, the impact of nursery environments on propagule quality has not been examined despite the importance of coral fitness for ensuring resistant populations. Here, we investigated two fitness indicators (lipid diversity and tissue protein abundance) of Acropora millepora adults and eggs grown on coral nurseries versus native reef on the GBR, with adults assessed at two sites (Blue Lagoon and Rayban) and eggs assessed at one site (Blue Lagoon). Lipid profiles of adult colonies varied by site and origin (nursery versus wild reef), with adult nursery corals exhibiting an elevated relative abundance of storage lipids (diacylglycerols and triacylglycerols) and lipid classes responsible for regulating membrane structure (phosphatidylcholines and sterol esters), while wild corals were characterised by a greater relative abundance of fatty acids and classes involved in immunoregulation. Comparing eggs from different origins, nursery offspring were richer in energy-storing triacylglycerols, as well as ceramides and phosphatidylcholines essential for membrane structure, while wild eggs had a greater relative abundance of wax ester species also important for energy storage. No differences were found in total protein abundance (adult or eggs) or egg physical characteristics (count and size) between nursery and wild origins. Variations in lipid profiles are consistent with differences in environmental conditions between reef sites and origin (nursery versus wild), highlighting the need to consider site selection and propagation conditions when planning restoration projects. Importantly, these findings demonstrate that the lipid classes with the highest relative abundance in A. millepora nursery and wild eggs differed from those in adults from the same origin, suggesting that propagation origin is more important for driving lipid profiles in coral eggs compared to parental effects. [ABSTRACT FROM AUTHOR]

The achievements in successfully establishing coral nurseries using asexually reproduced transplants in Kavaratti Island, Lakshadweep archipelago are presented. During the present study, the survival and growth of 180 fragments of corals fixed on concrete blocks with iron frames laid over a 40 m2 area near reefs inside the lagoon of Kavaratti atoll were assessed. Significant differences in growth were observed between acroporid and non-acroporid corals after two years of transplantation. Acropora muricata (31.1 ± 0.4 cm) and Isopora palifera (15.9 ± 3.4 cm) displayed the highest and lowest growth rates among acroporid corals and Pocillopora damicornis (481.9 ± 68.4 cm3) and Hydnophora microconos (33.4 ± 15.7 cm3) had the highest and lowest rates, among non-acroporid corals. A diverse fish assemblage comprising 21 species belonging to 10 families was observed at the transplantation site, with Chromis viridis and Dascyllus aruanus being the dominant species. The success achieved in this study makes it an ideal approach to be used elsewhere in the Lakshadweep archipelago and the wider Indian Ocean region to develop underwater tourism and promote science-based management and restoration of coral reefs. [ABSTRACT FROM AUTHOR]

Compact bushy and expansive branching Acropora survival rates were compared in an experimental restoration setting. Coral fragments were sourced as corals of opportunity (CoPs) or refragmented from CoPs reared on a floating mid‐water rope nursery. Fragments were attached in single‐species and mixed‐species aggregations to modular substrate stabilization structures (reef stars) on degraded, unconsolidated dead coral rubble slopes in Wakatobi Marine National Park, central Indonesia. In total, 1440 Acropora fragments were outplanted to 96 reef stars across five experimental restoration blocks at 14 m depth. Fragment survival was recorded 40–44 months post‐attachment. Survival had a significant relationship with fragment morphology (p < 0.001) and aggregation type (p < 0.01). Sourcing fragments as CoPs or from the nursery did not have a significant relationship with survival. No significant relationships were found with fragment survival for any interactions between morphology, outplanted aggregation, and source. Survival rates for bushy Acropora were 3.44 times and 5.25 times higher than for expansive species for direct CoP outplants and nursery‐reared corals, respectively. The results demonstrate the potential efficacy of returning complex bushy branching Acropora morphologies to mid‐depth reef slopes previously dominated by the genus, using single‐species aggregations interspersed with mixed‐species aggregations. The study also supports using mid‐water nurseries to create a closed or semi‐closed nursery cycle to scale up restoration, and proposes introducing the term "biomass production system" to distinguish this as a process distinct from other coral nursery approaches. [ABSTRACT FROM AUTHOR]

BACKGROUND: Coral diseases are one of the leading causes of declines in coral populations. In the Caribbean, white band disease (WBD) has led to a substantial loss of Acropora corals. Although the etiologies of this disease have not been well described, characterizing the coral microbiome during the transition from a healthy to diseased state is critical for understanding disease progression. Coral nurseries provide unique opportunities to further understand the microbial changes associated with diseased and healthy corals, because corals are monitored over time. We characterized the microbiomes before and during an outbreak of WBD in Acropora cervicornis reared in an ocean nursery in Little Cayman, CI. We asked (1) do healthy corals show the same microbiome over time (before and during a disease outbreak) and (2) are there disease signatures on both lesioned and apparently healthy tissues on diseased coral colonies? METHODS: Microbial mucus-tissue slurries were collected from healthy coral colonies in 2017 (before the disease) and 2019 (during the disease onset). Diseased colonies were sampled at two separate locations on an individual coral colony: at the interface of Disease and ∼10 cm away on Apparently Healthy coral tissue. We sequenced the V4 region of the 16S rRNA gene to characterize bacterial and archaeal community composition in nursery-reared A. cervicornis. We assessed alpha diversity, beta diversity, and compositional differences to determine differences in microbial assemblages across health states (2019) and healthy corals between years (2017 and 2019). RESULTS: Microbial communities from healthy A. cervicornis from 2017 (before disease) and 2019 (after disease) did not differ significantly. Additionally, microbial communities from Apparently Healthy samples on an otherwise diseased coral colony were more similar to Healthy colonies than to the diseased portion on the same colony for both alpha diversity and community composition. Microbial communities from Diseased tissues had significantly higher alpha diversity than both Healthy and Apparently Healthy tissues but showed no significant difference in beta-diversity dispersion. Our results show that at the population scale, Healthy and Apparently Healthy coral tissues are distinct from microbial communities associated with Diseased tissues. Furthermore, our results suggest stability in Little Cayman nursery coral microbiomes over time. We show healthy Caymanian nursery corals had a stable microbiome over a two-year period, an important benchmark for evaluating coral health via their microbiome.

The degradation of coral reefs during the last decades has turned attention toward management and restoration interventions. This study seeks to operationalize coral gardening of Pocillopora spp. fragments in low profile bottom‐anchored nurseries and to compare survival and growth patterns between sites, time, and fragment size in the southern Mexican Pacific. After 357 days, fragments showed high survival (96.4%), growth rates (4.35 cm/year), and an increase in coral coverage from 3.62 ± 1.3% (mean ± SD) to 17.42 ± 4.8% (approximately 480%). Coral growth rate did not show differences between sites (pseudo‐F[1,635] = 0.21, p = 0.63), but corals grew more significantly during the upwelling season in the Gulf of Tehuantepec. According to linear and local regression analysis, the extension rate in nurseries was significantly higher when corals were smaller (<7 cm in diameter) being of relevance for operationalizing coral gardening from donor colonies; nevertheless, coral shrinkage (13.1%), when corals were smaller (i.e. during the early phases of the coral gardening protocol), calls for precaution and close monitoring. Operationalizing coral gardening of Pocillopora spp. fragments, including successful metrics in upwelling areas, are relevant for reef restoration in the eastern tropical Pacific; nevertheless, lessons regarding shrinkage and differential growth rates related to coral size should also be considered. [ABSTRACT FROM AUTHOR]

Background. Coral diseases are one of the leading causes of declines in coral populations. In the Caribbean, white band disease (WBD) has led to a substantial loss of Acropora corals. Although the etiologies of this disease have not been well described, characterizing the coral microbiome during the transition from a healthy to diseased state is critical for understanding disease progression. Coral nurseries provide unique opportunities to further understand the microbial changes associated with diseased and healthy corals, because corals are monitored over time. We characterized the microbiomes before and during an outbreak of WBD in Acropora cervicornis reared in an ocean nursery in Little Cayman, CI. We asked (1) do healthy corals show the same microbiome over time (before and during a disease outbreak) and (2) are there disease signatures on both lesioned and apparently healthy tissues on diseased coral colonies? Methods. Microbial mucus-tissue slurries were collected from healthy coral colonies in 2017 (before the disease) and 2019 (during the disease onset). Diseased colonies were sampled at two separate locations on an individual coral colony: at the interface of Disease and ~10 cm away on Apparently Healthy coral tissue. We sequenced the V4 region of the 16S rRNA gene to characterize bacterial and archaeal community composition in nursery-reared A. cervicornis. We assessed alpha diversity, beta diversity, and compositional differences to determine differences in microbial assemblages across health states (2019) and healthy corals between years (2017 and 2019). Results. Microbial communities from healthy A. cervicornis from 2017 (before disease) and 2019 (after disease) did not differ significantly. Additionally, microbial communities from Apparently Healthy samples on an otherwise diseased coral colony were more similar to Healthy colonies than to the diseased portion on the same colony for both alpha diversity and community composition. Microbial communities from Diseased tissues had significantly higher alpha diversity than both Healthy and Apparently Healthy tissues but showed no significant difference in beta-diversity dispersion. Our results show that at the population scale, Healthy and Apparently Healthy coral tissues are distinct from microbial communities associated with Diseased tissues. Furthermore, our results suggest stability in Little Cayman nursery coral microbiomes over time. We show healthy Caymanian nursery corals had a stable microbiome over a two-year period, an important benchmark for evaluating coral health via their microbiome. [ABSTRACT FROM AUTHOR]

Identifying factors that influence nursery coral growth can help estimate nursery productivity and optimize yield. We examined the growth rates of Acropora cervicornis fragments from a nearshore nursery in Fort Lauderdale, Florida to determine how time after fragmentation, fragment type, donor colony nursery structure, and genotype influenced growth. Growth rates were calculated from linear extension measurements of fragments representing 10 coral host genotypes 27 and 61 days after fragmenting. Fragments were classified as apical (obtained from branch tips) or proximal (obtained midbranch), based on photographs. Donor colony nursery structure did not influence growth. A linear mixed‐effects model was performed to assess the influence of time, fragment type, and genotype on growth. Growth rates at 61 days were faster than at 27 days, and apical fragments grew faster than proximal fragments in 2 out of 10 genets at 61 days, providing some evidence for a trade‐off between growth and healing. We found no significant genet growth differences at 27 days. However, differences between genets were detected in 61‐day growth rates, suggesting that growth differences among distinct A. cervicornis genets propagated by asexual fragmentation may not emerge before 2 months, regardless of donor colony structure or fragment type. Our results suggest that restoration practitioners need not monitor growth between genets before 2 months to save resources from ongoing monitoring. In addition, scientists using coral fragments in experiments should be aware that growth differences between genets may take longer than 60 days to appear, posing some risk of confounding experimental results. [ABSTRACT FROM AUTHOR]

Background Coral diseases are one of the leading causes of declines in coral populations. In the Caribbean, white band disease (WBD) has led to a substantial loss of Acropora corals. Although the etiologies of this disease have not been well described, characterizing the coral microbiome during the transition from a healthy to diseased state is critical for understanding disease progression. Coral nurseries provide unique opportunities to further understand the microbial changes associated with diseased and healthy corals, because corals are monitored over time. We characterized the microbiomes before and during an outbreak of WBD in Acropora cervicornis reared in an ocean nursery in Little Cayman, CI. We asked (1) do healthy corals show the same microbiome over time (before and during a disease outbreak) and (2) are there disease signatures on both lesioned and apparently healthy tissues on diseased coral colonies? Methods Microbial mucus-tissue slurries were collected from healthy coral colonies in 2017 (before the disease) and 2019 (during the disease onset). Diseased colonies were sampled at two separate locations on an individual coral colony: at the interface of Disease and ∼10 cm away on Apparently Healthy coral tissue. We sequenced the V4 region of the 16S rRNA gene to characterize bacterial and archaeal community composition in nursery-reared A. cervicornis. We assessed alpha diversity, beta diversity, and compositional differences to determine differences in microbial assemblages across health states (2019) and healthy corals between years (2017 and 2019). Results Microbial communities from healthy A. cervicornis from 2017 (before disease) and 2019 (after disease) did not differ significantly. Additionally, microbial communities from Apparently Healthy samples on an otherwise diseased coral colony were more similar to Healthy colonies than to the diseased portion on the same colony for both alpha diversity and community composition. Microbial communities from Diseased tissues had significantly higher alpha diversity than both Healthy and Apparently Healthy tissues but showed no significant difference in beta-diversity dispersion. Our results show that at the population scale, Healthy and Apparently Healthy coral tissues are distinct from microbial communities associated with Diseased tissues. Furthermore, our results suggest stability in Little Cayman nursery coral microbiomes over time. We show healthy Caymanian nursery corals had a stable microbiome over a two-year period, an important benchmark for evaluating coral health via their microbiome.

As coral reefs continue to degrade at an alarming rate, coral restoration efforts are increasing worldwide in an attempt to keep up with the global challenge of preserving these iconic ecosystems and the many services they provide. Coral gardening, the farming and outplanting of coral fragments, is a commonly applied practice; however, regional validation is required before upscaling can be considered. This study follows up from the successful farming of fragments in mid‐water rope nurseries, by reporting on the successive outplanting of these corals. Specifically, 60 Pocillopora verrucosa colonies were outplanted to a degraded reef at different depths (1–12 m), applying three arrangement patterns (equal, clustered, random). After 1 year, 72% were considered successfully outplanted (alive and still attached), with detachment being the main challenge at wave‐impacted shallow depths, while loose coral rubble caused more partial mortality at depth. Outplanting stress was observed at 1–6 m depth, but had no impact on survival or growth. Drupella sp. predation was most common at 3 m and 79% of colonies hosted mutualistic fauna after 1 year. Outplanting significantly benefitted the reef environment with a higher fish abundance and diversity along with a higher increase in natural coral cover (H = 2.7; 6.2% increase) in comparison with the control sites. These are promising results, considering that the restoration site has shown little natural recovery in the last few years (coral cover <4%). We hope that our findings provide useful initial insights and help to guide effective restoration practices in the Maldives. [ABSTRACT FROM AUTHOR]

Since 1950, coral abundance has declined worldwide by an estimated 60%, and further dramatic declines are predicted. Although global reductions in carbon emissions are essential to prevent further loss, coral reef restoration has become imperative to maintain the ecosystem services that coral reefs provide to humans at local scales. Yet, currently coral restoration and gardening efforts are too expensive to scale up due to the labor-intensive nature of the methods and low success rates. Here, we present a suite of technologies that improve coral reef restoration and rehabilitation’s scalability, efficiency, and effectiveness. Our modular technologies are designed to streamline in and ex situ nursery workflows, reduce maintenance times, solve problems in transporting corals to outplanting sites, and enable rapid outplanting on natural and artificial substrates. These novel structures can act as coral seeding hubs, which placed strategically, can have the capacity to enhance coral reproduction and replenish degraded nearby reefs with larvae. They can be applied to coral restoration and reefscaping, complemented by unique eco-friendly, low-carbon-emission structures for the creation of architecturally and visually appealing habitats and underwater landscapes. Our technologies integrate novel monitoring approaches that support intelligent solutions to track genotypes, optimize and control stock management, apply assisted evolution approaches, and adaptive management through long-term monitoring.

The global decline of coral reefs has driven considerable interest in active coral restoration. Despite their importance and dominance on mature reefs, relatively few coral restoration projects use slower growth forms like massive and encrusting coral species. Micro-fragmentation can increase coral cover by orders of magnitude faster than natural growth, which now allows cultivation of slow growing massive forms and shows promise and flexibility for active reef restoration. However, the major causes of variation in growth and survival of outplanted colonies remain poorly understood. Here, we report simple outplanting assays to aid in active reef restoration of slower growing species and increase the likelihood of restoration success. We used two different micro-fragmentation assays. Pyramid assays were used to examine variation associated with fragment size (ranging from ≈1-9 cm2), nursery residence time (for both in-situ and ex-situ nurseries), and 2D vs. 3D measurements of growth. Block assays were used to examine spatial variation among individual performance at outplanting sites in the field. We found 2D and 3D measurements correlated well, so measured survivorship and growth using top-down planar images for two of the main Hawaiian reef building corals, the plating Montipora capitata and the massive Porites compressa. Pyramid assays housed and outplanted from the in-situ nursery showed no effect of residence time or size on overall survivorship or growth for either species. Results from the ex-situ nursery, however, varied by species, with P. compressa again showing no effect of nursery residence time or size on survivorship or growth. In contrast, nursery culture resulted in improved survivorship of small M. capitata fragments, but net growth showed a weak positive effect of nursery time for medium fragments. Small fragments still suffered higher mortality than either medium or large fragments. Due to their lower mortality, medium fragments (≈3 cm2) appear to be the best compromise between growth and survivorship for outplanting. Likewise, given weak positive gains relative to the investment, our results suggest that it could be more cost-effective to simply outplant medium fragments as soon as possible, without intermediate culture in a nursery. Furthermore, the block assay revealed significant differences in survivorship and growth among sites for individuals of both species, emphasizing the importance of considering spatial variation in coral survival and growth following outplanting. These results highlight the value of using short-term micro-fragmentation assays prior to outplanting to assess size, and location specific performance, optimizing the efficiency of active reef restoration activities and maximizing the probability of success for active coral restoration projects. [ABSTRACT FROM AUTHOR]

The global decline of coral reefs has driven considerable interest in active coral restoration. Despite their importance and dominance on mature reefs, relatively few coral restoration projects use slower growth forms like massive and encrusting coral species. Micro-fragmentation can increase coral cover by orders of magnitude faster than natural growth, which now allows cultivation of slow growing massive forms and shows promise and flexibility for active reef restoration. However, the major causes of variation in growth and survival of outplanted colonies remain poorly understood. Here, we report simple outplanting assays to aid in active reef restoration of slower growing species and increase the likelihood of restoration success. We used two different micro-fragmentation assays. Pyramid assays were used to examine variation associated with fragment size (ranging from ≈1–9 cm2), nursery residence time (for both in-situ and ex-situ nurseries), and 2D vs. 3D measurements of growth. Block assays were used to examine spatial variation among individual performance at outplanting sites in the field. We found 2D and 3D measurements correlated well, so measured survivorship and growth using top-down planar images for two of the main Hawaiian reef building corals, the plating Montipora capitata and the massive Porites compressa. Pyramid assays housed and outplanted from the in-situ nursery showed no effect of residence time or size on overall survivorship or growth for either species. Results from the ex-situ nursery, however, varied by species, with P. compressa again showing no effect of nursery residence time or size on survivorship or growth. In contrast, nursery culture resulted in improved survivorship of small M. capitata fragments, but net growth showed a weak positive effect of nursery time for medium fragments. Small fragments still suffered higher mortality than either medium or large fragments. Due to their lower mortality, medium fragments (≈3 cm2) appear to be the best compromise between growth and survivorship for outplanting. Likewise, given weak positive gains relative to the investment, our results suggest that it could be more cost-effective to simply outplant medium fragments as soon as possible, without intermediate culture in a nursery. Furthermore, the block assay revealed significant differences in survivorship and growth among sites for individuals of both species, emphasizing the importance of considering spatial variation in coral survival and growth following outplanting. These results highlight the value of using short-term micro-fragmentation assays prior to outplanting to assess size, and location specific performance, optimizing the efficiency of active reef restoration activities and maximizing the probability of success for active coral restoration projects.

The drastic decline in coral coverage has stimulated an interest in reef restoration, and various iterations of coral nurseries have been used to augment restoration strategies. Here we examine the growth of two species of Hawaiian Montipora that were maintained in mesocosms under either ambient or warmed annual bleaching conditions for two consecutive years prior to outplanting to determine whether preconditioning aided coral restoration efforts. Using coral trees to create a nearby ocean nursery, we examined whether: (1) previous ex situ mesocosm growth would mirror in situ coral tree nursery growth; and (2) thermal ex situ stress-hardening would predict future success during natural warming events in situ for corals moved from tanks to trees. For Montipora capitata, we found that variation in growth was explained primarily by genotype; growth rates in the mesocosms were similar to those in situ, irrespective of preconditioning. Variation in M. flabellata growth, however, was explained by both genotype and culture method such that an individual M. flabellata colony that grew well in the tanks did not necessarily perform as well on the coral trees. For both species, previous exposure to elevated temperatures in the mesocosms provided no benefit to either growth or survival during a warming event in the coral tree nursery compared to those grown in ambient temperatures. Overall, M. capitata performed better in the tree nursery with higher net growth, lower mortality, and was subject to less predation than M. flabellata. Our results show little benefit of the additional cost and time of stress-hardening these corals prior to outplanting because it is unlikely to aid resilience to future warming events. These results also suggest that selecting corals for restoration based on long-term genotype growth performance may be more effective for optimal outcomes but should be weighed against other factors, such as coral morphology, in situ nursery method, location, and other characteristics. [ABSTRACT FROM AUTHOR]

The drastic decline in coral coverage has stimulated an interest in reef restoration, and various iterations of coral nurseries have been used to augment restoration strategies. Here we examine the growth of two species of Hawaiian Montipora that were maintained in mesocosms under either ambient or warmed annual bleaching conditions for two consecutive years prior to outplanting to determine whether preconditioning aided coral restoration efforts. Using coral trees to create a nearby ocean nursery, we examined whether: (1) previous ex situ mesocosm growth would mirror in situ coral tree nursery growth; and (2) thermal ex situ stress-hardening would predict future success during natural warming events in situ for corals moved from tanks to trees. For Montipora capitata, we found that variation in growth was explained primarily by genotype; growth rates in the mesocosms were similar to those in situ, irrespective of preconditioning. Variation in M. flabellata growth, however, was explained by both genotype and culture method such that an individual M. flabellata colony that grew well in the tanks did not necessarily perform as well on the coral trees. For both species, previous exposure to elevated temperatures in the mesocosms provided no benefit to either growth or survival during a warming event in the coral tree nursery compared to those grown in ambient temperatures. Overall, M. capitata performed better in the tree nursery with higher net growth, lower mortality, and was subject to less predation than M. flabellata. Our results show little benefit of the additional cost and time of stress-hardening these corals prior to outplanting because it is unlikely to aid resilience to future warming events. These results also suggest that selecting corals for restoration based on long-term genotype growth performance may be more effective for optimal outcomes but should be weighed against other factors, such as coral morphology, in situ nursery method, location, and other characteristics.

Efforts to manage coral reef declines are increasingly turning towards in situ propagation of corals to aid reef recovery. Understanding the factors that influence 'success' throughout the propagation process is therefore critical to ensure efforts are viable and cost-effective, yet the extent to which propagation practices potentially impact the underlying coral biology remains unknown. Given growing evidence for the importance of the coral microbiome, we examined the influence of nursery-based propagation and out-planting on the bacterial communities of two coral species–Acropora millepora and Pocillopora verrucosa–increasingly propagated on the northern Great Barrier Reef (Opal Reef). Bacterial communities of coral fragments were characterised over four months of nursery propagation (sampling points: zero, seven and 125 days) and one month of subsequent out-planting (sampling points: zero, one and 30 days). Bacterial community structure differed between A. millepora and P. verrucosa throughout the experiment and species-specific temporal dynamics were observed during the transplantation of corals into nurseries and subsequent out-planting back to the reef. P. verrucosa bacterial community structure remained stable over time in the natural reef environment and within the nursery. In contrast, A. millepora bacterial communities within the nursery significantly changed over time, whereas those associated with source colonies within the natural reef environment remained unchanged. However, after one month of out-planting, the composition, richness and diversity of A. millepora bacterial communities were not statistically different to those associated with the source colonies. We interpret the transient shift of A. millepora bacterial communities within the nursery as an impact of distinctive environmental conditions in nurseries compared to natural reef settings, and the greater responsiveness of A. millepora bacterial communities to environmental change. Our observations highlight that different coral species exhibit distinct microbial responses to coral propagation and out-planting, and we recommend that these should be considered when designing and scaling future coral management strategies. [ABSTRACT FROM AUTHOR]

For decades, coral reef ecosystems have been in decline due to environmental stressors such as rising sea temperatures, increased disease prevalence, and other local anthropogenic sources. Considering this decline, coral restoration efforts in the Caribbean have been implemented to promote reef recovery with a focus on the coral genus Acropora. Current methods target the threatened species Acropora cervicornis and A. palmata, but little is known about the restoration potential of their hybrid taxon, A. prolifera. Using interspecific hybrids with higher fitness than one or both parental species has gained traction as a novel restoration technique. For this study, three in situ coral tree nurseries were established around Great Stirrup Cay, The Bahamas, to compare the growth and survival among acroporid taxa. Three 150 mm fragments from six putative genotypes of each acroporid taxa were collected from reefs around New Providence, The Bahamas, and transported to Great Stirrup Cay in June 2018. One fragment from each genotype was transported to each nursery site, cut into three sections (apical, middle, and basal), and suspended from PVC coral trees. Fragment survival was collected monthly for 13 months, and Total Linear Extension (TLE) values were calculated for each fragment monthly for 12 months. Nursery site significantly affected fragment survival, while taxon and fragment section did not. Total fragment mortality was 29.3% in the first month but ranged from 0 to 5% for the rest of the study period until July 2019 (32.7% of remaining fragments died primarily at N1). Overall, A. prolifera growth was significantly greater than the parental species. Taxon, nursery site, and fragment section were identified as important factors affecting TLE. Apical A. prolifera fragment sections at site N3 had the greatest average linear growth at 12 months and had the greatest average growth rate per month. This study highlights the rapid growth rate of hybrid corals and suggests that fragment sections have equivalent survival and growth. Consequently, these results suggest that restoration managers may capitalize on fast growing hybrids for outplanting to degraded reefs and to increase the scale of nursery projects.

Understanding the structural and mechanical properties of coral skeletons is important to assess their responses to natural and anthropogenic challenges and to predict the long-term viability of hermatypic corals in a changing ocean. Here, we describe the microstructure of the critically endangered staghorn coral (Acropora cervicornis) skeleton and its mechanical properties, spectral and fluidic behavior, including uniaxial compressive strength, resistance to plastic deformation, spectral vibrational response, and flow-field analysis. We evaluated skeletons of A. cervicornis retrieved from a nursery off Broward County, Florida, USA. Optical micrographs and X-ray computed topography revealed a complex system of canals and pores that allow rapid skeletal elongation while retaining sufficient strength to withstand currents, waves, and other physical forces. Compressive loading of the aragonite skeleton resulted in complex stress–strain deformation behavior; the unique pore arrangement resisted catastrophic cracks and prevented instantaneous failure. Vickers microhardness was 3.56 ± 0.31 GPa, which is typical for soft aragonite materials yet sufficient to withstand the hydraulic pressure of ocean waves. Impressions made by the diamond indenter had almost no cracks radiating from their corners, which again demonstrated the ability of the complex skeleton microstructure to suppress crack formation and growth (e.g., from the bites of grazers). Maps of the ν1 mode Raman peak of identation surfaces showed evidence of residual strain. However, the ν1 peak's position barely changed (from 1083.6 cm−1 outside the impression to 1083.9 cm−1 in the center), indicating weak stress sensitivity. Flow-field analysis revealed small-scale, counter-rotating vortices formed in the skeleton's wake, which can entrain food particles within range of polyp tentacles and facilitate transport of respiratory gases and wastes. Considered together, our results demonstrate that the perforate skeleton of A. cervicornis is well-adapted to withstand physical forces normally encountered in its shallow-water habitat, but may be susceptible to anthropogenic stressors that alter its architecture. [ABSTRACT FROM AUTHOR]

The 'gardening coral reefs' method is part of the approaches proposed for counteracting the substantial impacts of global climate change on the survival of coral reefs. It incorporates ecosystem engineering strategies for coral nursery farming and coral colonies out-planting. This study explores the reproductive output of three sets of nursery-grown Stylophora pistillata colonies along eight reproductive seasons following transplantation, as compared to that of native corals. When native and transplanted corals grew side by side in a disturbed environment, the nursery-grown transplants showed enhanced larval release (2.6–22.5 times more planulae/colony; multiyear average: 11.6±1.8 planulae/transplant vs. 1.5±0.3 planulae/native colony) with higher percentages of gravid colonies (91±2.1% transplants vs. 34±7.6% native colonies). The inherently enhanced larval production of transplants, maintained for such a long period of time post-transplantation, reveals a possible enduring impact of the nursery conditions on future fitness and ecological traits of transplants. This is further supported by the emerging documentation regarding the enhanced growth of corals under nursery conditions, which continues to be detected even years after transplantation was conducted on the natural reef. The above enhancement of coral reproduction can be harnessed as a human intervention tool for countering global climate change impacts. [ABSTRACT FROM AUTHOR]

Coral reefs support a biologically rich ecosystem and are economically invaluable. Unfortunately, due to several reasons including, but not limited to, human activities, global warming effects, and both biotic and abiotic stressors, coral reefs are gradually disappearing from Hawaii’s shorelines. This study introduces novel coral husbandry techniques to help restore injured coral reef habitats. The techniques presented in this work are focused on saving whole coral colonies detached from their bases (via wave action or other physical disturbances) instead of fragmenting existing colonies. Design, fabrication, assembly, and installation details of an in-water Fiberglass Reinforced Plastic (FRP) coral nursery structure are discussed in this work. Material selection and novel design of the coral nursery were specifically adapted to physical ocean conditions of the south shore of O’ahu, Hawaii. Factors such as safety, practicality, cost efficiency, transportation, installation, and attachment of coral colonies for systematic restoration efforts, while maintaining minimal environmental impact, were considered to design and build the coral nursery. Structural fatigue was investigated via finite element methods considering underwater loading and boundary conditions. FRP was chosen for the material by a trade-off comparison method. This structure was built, assembled, and deployed in south shore O’ahu, Hawaii, in April 2018. This study demonstrated the design, engineering, and build of a durable coral nursery structure.

Disease mortality has been a primary driver of population declines and the threatened status of the foundational Caribbean corals, Acropora palmata and A. cervicornis. There remain few tools to effectively manage coral disease. Substantial investment is flowing into in situ culture and population enhancement efforts, while disease takes a variable but sometimes high toll in restored populations. If genetic resistance to disease can be identified in these corals, it may be leveraged to improve resistance in restored populations and possibly lead to effective diagnostic tests and disease treatments. Using a standardized field protocol based on replicated direct-graft challenge assays, we quantified this important trait in cultured stocks from three field nurseries in the Florida Keys. Field tests of 12 genotypes of A. palmata and 31 genotypes of A. cervicornis revealed significant genotypic variation in disease susceptibility of both species measured both as risk of transmission (percent of exposed fragments that displayed tissue loss) and as the rate of tissue loss (cm2 d–1) in fragments with elicited lesions. These assay results provide a measure of relative disease resistance that can be incorporated, along with consideration of other important traits such as growth and reproductive success, into restoration strategies to yield more resilient populations.

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. [ABSTRACT FROM AUTHOR]

Disease mortality has been a primary driver of population declines and the threatened status of the foundational Caribbean corals, Acropora palmata and A. cervicornis. There remain few tools to effectively manage coral disease. Substantial investment is flowing into in situ culture and population enhancement efforts, while disease takes a variable but sometimes high toll in restored populations. If genetic resistance to disease can be identified in these corals, it may be leveraged to improve resistance in restored populations and possibly lead to effective diagnostic tests and disease treatments. Using a standardized field protocol based on replicated direct-graft challenge assays, we quantified this important trait in cultured stocks from three field nurseries in the Florida Keys. Field tests of 12 genotypes of A. palmata and 31 genotypes of A. cervicornis revealed significant genotypic variation in disease susceptibility of both species measured both as risk of transmission (percent of exposed fragments that displayed tissue loss) and as the rate of tissue loss (cm² d-1) in fragments with elicited lesions. These assay results provide a measure of relative disease resistance that can be incorporated, along with consideration of other important traits such as growth and reproductive success, into restoration strategies to yield more resilient populations. [ABSTRACT FROM AUTHOR]

In the Caribbean, corals are commonly cultured in ocean-based nurseries and outplanted back to reefs for population enhancement. Intraspecific diversity in host and symbiont is an important consideration for nursery and resource managers. We built upon a previous study that quantified Acropora cervicornis growth phenotypes in a nursery by outplanting the same genets across two reef sites and tracking their performance for 1 yr. Further, we identified the Symbiodinium ‘fitti’ strains present in each of the A. cervicornis genets during the restoration process from the initial wild collection as early as 2008 to 24 months post-outplant in 2017. Survival to 1 yr post-outplant was consistent with regional averages and did not differ significantly among A. cervicornis genets or between outplant sites. Outplant site and host genet had significant effects on coral growth. However, genet growth response did not depend on outplant site, providing no evidence for site-genet matching. Conversely, growth rates measured for each genet in the nursery were not predictive of performance following outplanting. Instead, A. cervicornis genets appear to exhibit differences in relative growth through the restoration process. Despite this variability, relative differences in growth among genets were consistent within a given timeframe, even across varying environments. Most colonies sampled were infected by one of five unique strains of S. ‘fitti’. Host-symbiont specificity varied among coral genets, but four out of five genets exhibited spatial and/or temporal differences in symbiont strain composition throughout the restoration process. The ability for A. cervicornis to associate with more than one S. ‘fitti’ strain and the lack of correlation between nursery and outplant growth performance contribute to a growing understanding of the A. cervicornis population enhancement process. [ABSTRACT FROM AUTHOR]

Acropora cervicornis is the most widely used coral species for reef restoration in the greater Caribbean. However, outplanting methodologies (e.g., colony density, size, host genotype, and attachment technique) vary greatly, and to date have not been evaluated for optimality across multiple sites. Two experiments were completed during this study, the first evaluated the effects of attachment technique, colony size, and genotype by outplanting 405 A. cervicornis colonies, from ten genotypes, four size classes, and three attachment techniques (epoxy, nail and cable tie, or puck) across three sites. Colony survival, health condition, tissue productivity, and growth were assessed across one year for this experiment. The second experiment assessed the effect of colony density by outplanting colonies in plots of one, four, or 25 corals per 4 m2 across four separate sites. Plot survival and condition were evaluated across two years for this experiment in order to better capture the effect of increasing cover. Colonies attached with a nail and cable tie resulted in the highest survival regardless of colony size. Small corals had the lowest survival, but the greatest productivity. The majority of colony loss was attributed to missing colonies and was highest for pucks and small epoxied colonies. Disease and predation were observed at all sites, but did not affect all genotypes, however due to the overall low prevalence of either condition there were no significant differences found in any comparison. Low density plots had significantly higher survival and significantly lower prevalence of disease, predation, and missing colonies than high density plots. These results indicate that to increase initial outplant success, colonies of many genotypes should be outplanted to multiple sites using a nail and cable tie, in low densities, and with colonies over 15 cm total linear extension.

Elkhorn coral (Acropora palmata) populations provide important ecological functions on shallow Caribbean reefs, many of which were lost when a disease reduced their abundance by more than 95% beginning in the mid-1970s. Since then, a lack of significant recovery has prompted rehabilitation initiatives throughout the Caribbean. Here, we report the first successful outplanting and long-term survival of A. palmata settlers reared from gametes collected in the field. A. palmata larvae were settled on clay substrates (substrate units) and either outplanted on the reef two weeks after settlement or kept in a land-based nursery. After 2.5 years, the survival rate of A. palmata settlers outplanted two weeks after settlement was 6.8 times higher (3.4%) than that of settlers kept in a land-based nursery (0.5%). Furthermore, 32% of the substrate units on the reef still harbored one or more well-developed recruit compared to 3% for substrate units kept in the nursery. In addition to increasing survival, outplanting A. palmata settlers shortly after settlement reduced the costs to produce at least one 2.5-year-old A. palmata individual from $325 to $13 USD. Thus, this study not only highlights the first successful long-term rearing of this critically endangered coral species, but also shows that early outplanting of sexually reared coral settlers can be more cost-effective than the traditional approach of nursery rearing for restoration efforts aimed at rehabilitating coral populations.

Acropora cervicornis is the most widely used coral species for reef restoration in the greater Caribbean. However, outplanting methodologies (e.g., colony density, size, host genotype, and attachment technique) vary greatly, and to date have not been evaluated for optimality across multiple sites. Two experiments were completed during this study, the first evaluated the effects of attachment technique, colony size, and genotype by outplanting 405 A. cervicornis colonies, from ten genotypes, four size classes, and three attachment techniques (epoxy, nail and cable tie, or puck) across three sites. Colony survival, health condition, tissue productivity, and growth were assessed across one year for this experiment. The second experiment assessed the effect of colony density by outplanting colonies in plots of one, four, or 25 corals per 4 m² across four separate sites. Plot survival and condition were evaluated across two years for this experiment in order to better capture the effect of increasing cover. Colonies attached with a nail and cable tie resulted in the highest survival regardless of colony size. Small corals had the lowest survival, but the greatest productivity. The majority of colony loss was attributed to missing colonies and was highest for pucks and small epoxied colonies. Disease and predation were observed at all sites, but did not affect all genotypes, however due to the overall low prevalence of either condition there were no significant differences found in any comparison. Low density plots had significantly higher survival and significantly lower prevalence of disease, predation, and missing colonies than high density plots. These results indicate that to increase initial outplant success, colonies of many genotypes should be outplanted to multiple sites using a nail and cable tie, in low densities, and with colonies over 15 cm total linear extension. [ABSTRACT FROM AUTHOR]

Phase shifts from coral- to algal-dominated reefs have grave effects on reef biodiversity and key ecosystem functions, further influencing management approaches that have generated fewer returns than desired. Harnessing the ability of corals to ‘self-anchor’ to substrates and of tissue fusions between isogeneic fragments, we develop here a novel ecological engineering approach based on the 2D Coral Preparative (2D-CP) tool. Using this tool we propose to create flat, two dimensional coral units that are first grown in a mid-water coral nursery and then transplanted to overlay phase-shifted coral reef surfaces as floor tiles. Here, we assess the feasibility of the 2D-CP’s first stage- growth in the nursery. Ten coral colonies from each of the species: Stylophora pistillata , Pocillopora damicornis and Cyphastrea spp. were collected from localities at the northern Gulf of Eilat (Red Sea, Israel), fragmented into nubbins and glued onto flat surfaces (CDs) to create 235 2D-CP units (32 nubbins/unit). All 2D-CPs were hung in a mid-water coral nursery, in both horizontal and vertical positions, and were digitally photographed once a month for a year. Images of each 2D-CP were used to determine the percentages of live coral tissue coverage on the substrates and the nubbins’ survival percentage. Results revealed high survival rates, with >80% of the 2D-CPs possessing live coral tissues at 12 months post setup (mps). The nubbins of all three species displayed an extensive 2D growth on the substrates, and as of 6–7 months (species and genotype specific) many of the 2D-CPs were completely covered with coral tissue (20% of all the 2D-CPs showed >100% coral coverage at 12 mps). The coral coverage of S. pistillata and P. damicornis 2D-CPs was significantly higher in the vertical placement position, 1.5 and 3 times, respectively. Overall, these results imply that the 2D-CP units can be successfully grown in a coral nursery for the purpose of creating ‘live tiles’ that can be placed directly over a denuded reef covered by turf algae, a novel ecological engineering tool to be used for coral-algae phase shifts reversals. We further anticipate that even in completely/partially dead 2D-CP units, newly exposed calcium carbonates would be expended as preferable substrates for either coral larval recruitment or coralline algae growth, boosting reef rehabilitation. [ABSTRACT FROM AUTHOR]

Seawalls, which have replaced many natural shorelines in coastal cities, are increasingly built to alleviate the impacts of rising sea levels. To mitigate the consequential loss of biodiversity, novel approaches such as ecological engineering have been adopted to enhance the biodiversity on these artificial structures. However, the majority of research to date has focused on physical modifications of intertidal seawalls, and such habitat enhancement efforts are labour- and cost-intensive. We examined the feasibility of transplanting nursery-reared scleractinian corals on subtidal seawalls in Singapore with the help of volunteers. Fragments of six hard coral species ( Pocillopora damicornis, Hydnophora rigida , Merulina ampliata, Podabacia crustacea, Echinopora lamellosa, Platygyra sinensis ) were tested. Fragments of all species fared well in the nurseries with a mean survival rate of 98.5% and 1.1 to 4-fold increase in live tissue area. Six months after transplantation to a seawall, only 50% of P. damicornis transplants survived, while those of M. ampliata decreased in size. Transplants of the other four species exhibited sustained growth and high survival rates (>90%), suggesting that they were more suitable than the former two species as candidates for transplantation onto subtidal seawalls. Scleractinian cover at the transplant site increased from 3% to 20% and generic richness increased from two to eight. The estimated project costs were almost US$ 23,000 if only researchers were involved in the effort, but the inclusion of volunteers in fieldwork and data analyses could help to bring the expenditure down by up to 23%. The study demonstrated the feasibility of transplanting corals onto subtidal seawalls to mitigate the impacts of coastal development, and highlighted its potential for application on other artificial structures. The findings also show that synergy between the community and scientists helps to reduce overall costs and is beneficial for biodiversity enhancement initiatives. [ABSTRACT FROM AUTHOR]

Since the listing of Acropora palmata and A. cervicornis under the US Endangered Species Act in 2006, increasing investments have been made in propagation of listed corals (primarily A. cervicornis, A. palmata to a much lesser extent) in offshore coral nurseries and outplanting cultured fragments to reef habitats. This investment is superimposed over a spatiotemporal patchwork of ongoing disturbances (especially storms, thermal bleaching, and disease) as well as the potential for natural population recovery. In 2014 and 2015, we repeated broad scale (>50 ha), low precision Acropora spp. censuses (i.e., direct observation by snorkelers documented via handheld GPS) originally conducted in appropriate reef habitats during 2005–2007 to evaluate the trajectory of local populations and the effect of population enhancement. Over the decade-long study, A. palmata showed a cumulative proportional decline of 0.4 –0.7x in colony density across all sites, despite very low levels of outplanting at some sites. A. cervicornis showed similar proportional declines at sites without outplanting. In contrast, sites that received A. cervicornis outplants showed a dramatic increase in density (over 13x). Indeed, change in A. cervicornis colony density was significantly positively correlated with cumulative numbers of outplants across sites. This study documents a substantive reef-scale benefit of Acropora spp. population enhancement in the Florida Keys, when performed at adequate levels, against a backdrop of ongoing population decline.

Coastal development is often at odds with coral reef conservation. In Aqaba, Jordan, authorities proposed a plan to relocate the existing port services to a new area on Al-Dirreh Bay towards the southern end of the Gulf of Aqaba. As a mitigation measure, 7000 endangered coral colonies were moved from Al-Dirreh and transplanted into degraded reef sites in Aqaba Marine Park. Sample survival and linear growth rates were determined biannually for 2 years and compared to growth rates at a control site. The overall survival rate for the transplanted colonies was estimated to exceed 87 % and the linear growth rates of the 16 species studied showed very similar values to colonies of the same species at the control site. Three species, Goniastrea edwardsi, Acropora arabensis and Stylophora pistillata, demonstrated more than 1 cm of linear growth per year. In addition, a nursery of coral nubbins from three species, Acropora hemprichii, S. pistillata and Pocillopora damicornis, was established to be a sustainable source of fully grown colonies. Their survival and linear growth rates were also measured over the 2-year period. The overall survival rate of the nubbins was 88 %, and the annual linear growth rate ranged from 0.32 cm for A. hemprichii to 0.99 cm for S. pistillata. High survival and linear growth rates indicate that the transplantation site selection and the techniques employed were successful. The results of this work support the premise that endangered coral colonies can be translocated to other reef areas and that coral nurseries can be set up to produce multiple fully grown colonies for future reef rehabilitation projects. [ABSTRACT FROM AUTHOR]

Abstract Coral nurseries and active restoration efforts are becoming widespread throughout the world as coral reef ecosystems collapse from local and global threats. This workshop brought ~ 45 local and national participants together at the Hawai‘i Institute of Marine Biology (HIMB) in July 2017 to form a working group and discuss past, present, and future coral restoration efforts in Hawai'i. Although restoration efforts in Hawai‘i are in the formative stages, there are currently several large projects including: (1) an ex-situ (land based) Coral Restoration Nursery facility recently constructed by the State of Hawai‘i Division of Aquatic Resources (DAR); (2) in-situ restoration activities by NOAA, and HIMB; (3) cultivation and transplantation work by the Maui Ocean Center (MOC), and; (4) ongoing experimental work at UH Mānoa. This workshop focused on Hawai‘i specific challenges, and developing new capacity and tools such as coral nurseries, transplantation methods, micro-fragmentation, assisted evolution, cryopreservation, conservation genetics, genomics, transcriptomics, and proteomics. The goal of the workshop was to provide an overview of current efforts and highlight the array of tools available to provide a foundation to fuel future coordination and collaboration efforts. [ABSTRACT FROM AUTHOR]

The continued decline of coral reefs worldwide due to natural and anthropogenic drivers necessitates the development of effective restoration schemes. Two of the approaches frequently used nowadays are (1) the direct transplantation of coral fragments/colonies to degraded reefs; and (2) the “coral gardening” approach, which supports coral transplantation only following an intermediate nursery phase, where corals are farmed until reaching suitable sizes. Both approaches are evaluated for the quality of transplanted coral material, employing two field experiments on fragments from Echinopora lamellosa and Merulina scabricula , non-branching, slow growing coral species (Scleractinia) commonly residing in the reef of Bolinao, Pangasinan, northwestern Philippines. Each experiment included an abridged (shortened) nursery phase of 1 year. The first experiment assessed the performance of two newly collected groups of coral fragments, one reared in situ within a coral nursery and the second directly transplanted to coral-denuded bommies. The second experiment evaluated the post-transplantation performance of nursery-reared colonies against similar-sized freshly collected coral fragments, both transplanted onto denuded bommies. Growth rate (buoyant weight and size increments), survivorship and attachment were compared within each experiment. While in the first experiment, clear patterns for enhanced growth, survivorship and attachment rates were recorded in the nursery farmed fragments as compared to directly transplanted nubbins, no such differences were found between the two coral groups in the second experiment, indicating that short-term nursery farming of slow growing corals does not improve their post-transplantation performance. However, since growth and survivorship during the nursery phase are enhanced, an abridged nursery farming stage may serve as an ecological engineering tool for the production of augmented numbers of coral material for transplantation. Follow-up studies such as testing the fragment size along with nursery time for various coral species of different growth patterns are indispensable for the improvement of the “coral gardening” protocols. [ABSTRACT FROM AUTHOR]

Abstract: The ‘gardening concept’ for reef restoration focuses on coral colonies farming in mid-water nurseries before their transplantation onto denuded reef areas. Nurseries situated in a nutrient-enriched environment significantly curtail nursery time, but extend labor, as nursery construction and farmed corals must be frequently cleaned from competing fouling organisms. Mass farming of corals calls, therefore, for efficient and cheap maintenance methodologies, which we here tested by employing Aqua-guard M250, an anti-fouling agent used in the fish farming industry. We found that this anti-fouling paint, while reducing fouling organisms on nursery components during the crucial phase of coral ramets'' development from nubbins and small fragments sizes to colony sizes suitable for transplantation, is not toxic to maricultured coral fragments that staged more than 2 cm away from the paint. Applying small quantities of such antifouling paint to coral nurseries, while restricting its use to nursery components that are not in direct contact with farmed coral material, reduces fouling coverage and cleaning procedures by 90%. [Copyright &y& Elsevier]

Hard bottom substrates that are the hallmark property of the coral reefs can be expanded by transforming sedimentary areas into engineered reefs. Testing this rationale, we developed here two preset coral-carpet prototypes ('coral sods'; 6 units, each 7.5 m2), one containing branching species and one with both coral forms (mixed-units) that were transplanted on a soft bottom area, containing 10 coral species (five branching, five massive; 354 ramets from 30 genotypes and 181 whole-colonies). Ramets from branching genotypes were distributed in central and peripheral coral-sod locations, whereas all massive colonies were put in central locations. The 'coral sod' carpets were set-up at the Eilat, Red Sea nursery, held in place for 2–8 months, then transplanted into a highly hostile soft-bottom area (15 m depth) and monitored for up to 17 months. Results revealed high survival rates for corals in the peripheral/center positions (80–100%; most combinations). A fast increase in ecological volume (EV) was recorded during 447 residency days, up to 112% in EV for Acropora variabilis mixed-units in the peripheral position. There was no statistically significant difference between treatments and sod's locations, except for the Pocillopora. damicornis branching/mixed treatment. At day 514, corals' aerial coverage has increased from 50% at onset to 67.3% for the branching units and to 61.5% in the mixed-units. Larvae released from transplanted Stylophora pistillata corals outperformed those of natal colonies in the two following reproductive seasons, significantly higher in the first reproductive season when compared to the second. Coral recruitment (day 485) was up to 4 times higher in the centers compared to the peripheries, in both coral-sod types. Using gypsum sticks dissipation, we recorded reduced water velocities at lateral and uppermost colonial architectures and in the coral sod centers as compared to peripheries. These results reveal the first steps for improved 'coral sod' units aiming to shape sandy tropical areas into flourishing coral reef sites. [ABSTRACT FROM AUTHOR]

Since the listing of Acropora palmata and A. cervicornis under the US Endangered Species Act in 2006, increasing investments have been made in propagation of listed corals (primarily A. cervicornis , A. palmata to a much lesser extent) in offshore coral nurseries and outplanting cultured fragments to reef habitats. This investment is superimposed over a spatiotemporal patchwork of ongoing disturbances (especially storms, thermal bleaching, and disease) as well as the potential for natural population recovery. In 2014 and 2015, we repeated broad scale (>50 ha), low precision Acropora spp. censuses (i.e., direct observation by snorkelers documented via handheld GPS) originally conducted in appropriate reef habitats during 2005-2007 to evaluate the trajectory of local populations and the effect of population enhancement. Over the decade-long study, A. palmata showed a cumulative proportional decline of 0.4 -0.7x in colony density across all sites, despite very low levels of outplanting at some sites. A. cervicornis showed similar proportional declines at sites without outplanting. In contrast, sites that received A. cervicornis outplants showed a dramatic increase in density (over 13x). Indeed, change in A. cervicornis colony density was significantly positively correlated with cumulative numbers of outplants across sites. This study documents a substantive reef-scale benefit of Acropora spp. population enhancement in the Florida Keys, when performed at adequate levels, against a backdrop of ongoing population decline., Competing Interests: The authors declare there are no competing interests.