Coral Nurseries Research Articles

Intraspecific variation in polar and nonpolar metabolite profiles of a threatened Caribbean coral.

Research aimed at understanding intraspecific variation among corals could substantially increase understanding of coral biology and improve outcomes of active restoration efforts. Metabolomics is useful for identifying physiological drivers leading to variation among genotypes and has the capacity to improve our selection of candidate corals that express phenotypes beneficial to restoration. Our study aims to compare metabolomic profiles among known, unique genotypes of the threatened coral Acropora cervicornis. In doing so, we seek information related to the physiological characteristics driving variation among genotypes, which could aid in identifying genets with desirable traits for restoration. We applied proton nuclear magnetic resonance (1H-NMR) and liquid chromatography-mass spectrometry (LC-MS) to identify and compare metabolomic profiles for seven unique genotypes of A. cervicornis that previously exhibited phenotypic variation in a common garden coral nursery. Significant variation in polar and nonpolar metabolite profiles was found among A. cervicornis genotypes. Despite difficulties identifying all significant metabolites driving separation among genotypes, our data support previous findings and further suggest metabolomic profiles differ among various genotypes of the threatened species A. cervicornis. The implementation of metabolomic analyses allowed identification of several key metabolites driving separation among genotypes and expanded our understanding of the A. cervicornis metabolome. Although our research is specific to A. cervicornis, these findings have broad relevance for coral biology and active restoration. Furthermore, this study provides specific information on the understudied A. cervicornis metabolome and further confirmation that differences in metabolome structure could drive phenotypic variation among genotypes.

Coral Reef Restorations Can Be Optimized to Reduce Coastal Flooding Hazards

Coral reefs are effective natural coastal flood barriers that protect adjacent communities. Coral degradation compromises the coastal protection value of reefs while also reducing their other ecosystem services, making them a target for restoration. Here we provide a physics-based evaluation of how coral restoration can reduce coastal flooding for various types of reefs. Wave-driven flooding reduction is greatest for broader, shallower restorations on the upper fore reef and between the middle of the reef flat and the shoreline than for deeper locations on the fore reef or at the reef crest. These results indicate that to increase the coastal hazard risk reduction potential of reef restoration, more physically robust species of coral need to be outplanted to shallower, more energetic locations than more fragile, faster-growing species primarily being grown in coral nurseries. The optimization and quantification of coral reef restoration efforts to reduce coastal flooding may open hazard risk reduction funding for conservation purposes.

The performance of coral nursery with rope tree techniques in the moderate sea current environment: Morotai pilot project

Acknowledged as the famous destination for shark diving tourism, Morotai waters poses increasing coral reef degradation risk in recent years. Coral restoration program is needed to battle the decreasing coral cover in this waters. Instead of garnering the fragment directly from healthy coral reef habitat, which is potentially damaging the healthy coral reef, a coral nursery can be proposed as an alternative method to maintain the pristine environment of coral reef habitat in Morotai waters with future coral restoration programs. Coral rope tree nursery has proven to be effective at achieving growth speed compared to other coral nursery methods as well as high performance to withstand moderate current risk. Performance of a pilot project of coral tree rope nursery in Morotai waters has been studied for more than five months and it shows as promising method for future massive nursery.

Conservation actions and ecological context: optimizing coral reef local management in the Dominican Republic.

Over the past few decades, coral reef ecosystems have been lost at accelerated rates as a result of global climate change and local stressors. Local management schemes can help improve the condition of coral reefs by enhancing their ecosystem recovery capacity. Caribbean conservation efforts include mitigation of local anthropogenic stressors, and integrating social participation. Here, we analyzed the case of the Bayahibe reefs in the Southeastern (SE) Dominican Republic to identify conservation actions and illustrate a conceptual example of local seascape management. We assessed reef health indicators from 2011 to 2016. Overall, our results show increases in total fish biomass, in both commercial and herbivorous fishes. Mean live coral cover was 31% and fleshy macroalgae was 23% after multiple disturbances such as Hurricanes Sandy and Isaac (2012), Mathew (2016) and heat stress presented in the study area in 2015. We also described actions taken by stakeholders and government institutions, including the implementation of a policy declaring an area of 869,000 ha as a marine protected area (MPA), enhanced water quality treatment, local restrictions to vessel traffic, enforcement of fishing regulations, and the removal of invasive lionfish (Pterois spp.). In addition, a restoration program for the threatened staghorn coral (Acropora cervicornis) was established in 2011, and currently has eight coral nurseries and six outplanting sites. Considering the biology and ecology of these reefs, we observed good results for these indicators (live coral cover, fish biomass, and water quality) in contrast with severely degraded Caribbean reefs, suggesting that optimizing local management may be a useful example for improving reef condition. Our results provide an overview of trends in reef condition in the SE Dominican Republic and could support current strategies to better protect reefs in the region. Given that Caribbean coral reefs face extreme challenges from global climate change, management measures may improve reef conditions across the region but stronger policy processes and increased scientific knowledge are needed for the successful management of coral reefs.

Coral growth, survivorship and return-on-effort within nurseries at high-value sites on the Great Barrier Reef.

Coral reefs are deteriorating worldwide prompting reef managers and stakeholders to increasingly explore new management tools. Following back-to-back bleaching in 2016/2017, multi-taxa coral nurseries were established in 2018 for the first time on the Great Barrier Reef (GBR) to aid reef maintenance and restoration at a "high-value" location-Opal Reef-frequented by the tourism industry. Various coral species (n = 11) were propagated within shallow water (ca. 4-7m) platforms installed across two sites characterised by differing environmental exposure-one adjacent to a deep-water channel (Blue Lagoon) and one that was relatively sheltered (RayBan). Growth rates of coral fragments placed onto nurseries were highly variable across taxa but generally higher at Blue Lagoon (2.1-10.8 cm2 month-1 over 12 months) compared to RayBan (0.6-6.6 cm2 month-1 over 9 months). Growth at Blue Lagoon was largely independent of season, except for Acropora tenuis and Acropora hyacinthus, where growth rates were 15-20% higher for December 2018-July 2019 ("warm season") compared to August-December 2018 ("cool season"). Survivorship across all 2,536 nursery fragments was ca. 80-100%, with some species exhibiting higher survivorship at Blue Lagoon (Acropora loripes, Porites cylindrica) and others at RayBan (A. hyacinthus, Montipora hispida). Parallel measurements of growth and survivorship were used to determine relative return-on-effort (RRE) scores as an integrated metric of "success" accounting for life history trade-offs, complementing the mutually exclusive assessment of growth or survivorship. RRE scores within sites (across species) were largely driven by growth, whereas RRE scores between sites were largely driven by survivorship. The initial nursery phase of coral propagation therefore appears useful to supplement coral material naturally available for stewardship of frequently visited Great Barrier Reef tourism (high-value) sites, but further assessment is needed to evaluate how well the growth rates and survival for nursery grown corals translate once material is outplanted.

Evaluating the potential for autonomous measurements of net community production and calcification as a tool for monitoring coral restoration

As coral restoration efforts increase globally, there is a growing need to not only increase post-restoration monitoring, but also advance reef restoration monitoring methods. Utilizing autonomous technology to compliment manual, SCUBA-based monitoring will diversify the types of data available to coral restoration practitioners and aid in determining the efficacy of restoration efforts. This study sought to investigate how existing reef monitoring technologies can be applied to coral restoration to improve monitoring resolution and assess restoration progress. The Benthic Ecosystem and Acidification Measurement System, which uses the gradient flux approach to measure benthic community metabolism, was used to monitor two arrays of nursery grown Acropora cervicornis within an offshore coral nursery in the Florida Keys. The first deployment monitored corals arranged in a density mimicking pre-restoration coral cover, while the second deployment monitored corals arranged in a density mimicking a reef site recently restored with nursery-grown A. cervicornis. The post-restoration density demonstrated a 36% increase in the observed ratio of net community calcification to net community production as compared to the pre-restoration density. Additionally, the post-restoration density demonstrated net accretion throughout the observation period (20 mmol CaCO3 m−2d−1) as compared to the pre-restoration density which experienced net dissolution (−5.0 mmol CaCO3 m−2d−1). Overall, the results of this study are promising indicators that metabolic monitoring could one day be widely utilized within the coral restoration field to remotely monitor benthic composition changes associated with coral restoration progress over time, providing valuable information to restoration practitioners, stakeholders, and resource managers.

Micro-Fragmentation as an Effective and Applied Tool to Restore Remote Reefs in the Eastern Tropical Pacific.

Coral reef ecosystems are continuously degraded by anthropogenic and climate change drivers, causing a widespread decline in reef biodiversity and associated goods and services. In response, active restoration methodologies and practices have been developed globally to compensate for losses due to reef degradation. Yet, most activities employ the gardening concept that uses coral nurseries, and are centered in easily-accessible reefs, with existing infrastructure, and impractical for coral reefs in remote locations. Here we evaluate the effectiveness of direct outplanting of coral micro-fragments (Pavona clavus and Pocillopora spp.) as a novel approach to restore remote reefs in the Islas Marías archipelago in the Eastern Tropical Pacific. Coral growth (height-width-tissue cover), survival percentage, extension rates (cm year−1), skeletal density (g cm−3) and calcification rates (g cm−2 year−1) were assessed over 13 months of restoration. In spite of detrimental effects of Hurricane Willa, transplants showed a greater-than-twofold increase in all growth metrics, with ~58–61% survival rate and fast self-attachment (within ~3.9 months) for studied species, with Pocilloporids exhibiting higher extension, skeletal density, and calcification rates than Pavona. While comprehensive long-term studies are required, direct transplantation methodologies of coral micro-fragments are emerging as time-effective and affordable restoration tools to mitigate anthropogenic and climate change impacts in remote and marginal reefs.

Long-term heightened larval production in nursery-bred coral transplants

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.

Detachment of Porites cylindrica nubbins by herbivorous fishes

A form of active restoration for coral assemblages involves culturing coral nubbins at nursery sites before transplantation to recipient reefs. Incidental grazing and/or directed predation by local fish assemblages are major sources of dislodgement and mortality for coral nubbins in nurseries. However, the rate of coral nubbin detachment, how this varies across fish taxa, and whether nubbin size affects rates of detachment warrant further investigation. We used field and aquaria experiments to examine the effect of incidental grazing and predation on the detachment of Porites cylindrica nubbins of different sizes (0.5, 1, 2, 3, 4, and 5 cm height). Short‐term (6 hours) exposure of nubbins to local fish assemblages at Lucero Reef, northwestern Philippines, caused higher detachment (1.93% ± 0.53 SE) compared to caged controls (0.16% ± 0.16 SE), with no detectable effect of nubbin size. To identify the impact of individual fish species, nubbins were exposed to one of four locally abundant herbivorous and corallivorous fish species in aquaria for 8 hours. Nubbin detachment was greater when exposed to Chlorurus spilurus (1.20–36.2%) and Siganus fuscescens (0.00–15.0%) than Chaetodon lunulatus (0.00–4.00%) and Chaetodon kleinii (0.00–1.20%), with the smallest nubbins (0.5 cm) being the most vulnerable. Our results suggest that incidental grazing by herbivorous fishes, especially parrotfishes, may potentially be an important source of detachment and likely mortality of nubbins. Optimizing coral nursery protocols should consider potential trade‐offs between excluding grazing fishes and the accumulation of algal material on caging structures to minimize nubbin mortality and improve coral restoration success.

Coral reef restoration in the Eastern Tropical Pacific: feasibility of the coral nursery approach

Due to the worldwide degradation of coral reefs, the active restoration of these ecosystems has received considerable attention in recent decades. This study investigated (1) the feasibility of using coral nurseries for restoration projects, (2) the minimum size required for a Pocillopora damicornis (Pocilloporidae) coral fragment to survive and grow in a nursery, and (3) the optimal transplant size of a fragment when transplanted to a degraded reef at Gorgona Island (Colombian Pacific). For this investigation, 230 fragments were transplanted directly to El Remanso reef, and another 150 fragments were maintained in in situ nurseries. Every 2 months, the length, weight, and survival of the fragments were recorded. After growing for 134 days in the nurseries, the 52 surviving fragments were transplanted to El Remanso reef, and after 5 months, the same variables were measured. Among the nursery‐reared fragments, the largest (4 to <8 cm) had the highest survival and growth rates, whereas among the directly transplanted fragments, the smallest fragments (<2 cm) had the highest survival and growth rates. However, the nursery‐reared fragments acquired greater structural complexity (arborescent morphology), and they were all alive 156 days after transplantation and presented a maximum linear growth rate of over 2 cm, which was higher than that of the directly transplanted fragments. Apparently, the arborescent morphology acquired during the nursery period provides advantages to the colonies that favor greater success when transplanted. Therefore, nursery‐reared fragments of P. damicornis between 2 and 4 cm are the most appropriate for use in restoration projects.

Design, Fabrication, Installation, and Population of a Novel Fiberglass Reinforced Plastic Coral Nursery Structure Off the South Shore of O’ahu, Hawaii

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. Fiberglass Reinforced Plastic (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.

The role of in situ coral nurseries in supporting mobile invertebrate epifauna

Coral nurseries are commonly employed to generate coral material for reef restoration projects, but observations of epifaunal organisms utilising the nurseries for food and shelter indicate that they can also provide important functions beyond that of coral propagation. To examine the level of biodiversity that can be supported by coral nurseries, and investigate if epifaunal communities were influenced by the presence of live coral tissue, we compared the abundance, diversity and community composition of mobile invertebrate epifauna associated with live and dead fragments of three coral species (Pocillopora acuta, Echinopora lamellosa, Platygyra sinensis) that were reared in an in situ nursery. A total of 418 mobile invertebrates spanning 63 taxa were recorded from 22 coral colonies. The three coral species hosted significantly different epifaunal communities, most likely a consequence of the difference in growth forms of the coral hosts. Significant differences in epifaunal communities were only observed between live and dead colonies of P. acuta, indicating that resource provisioning in this species is particularly influenced by the presence of live tissue. Our findings showed that coral nurseries can support a range of mobile invertebrates and function as tools to conserve threatened mobile invertebrates. This ecological function is under-studied and should be assessed in restoration programs for the conservation of corals and associated fauna.

Using naturally occurring climate resilient corals to construct bleaching-resistant nurseries

Ecological restoration of forests, meadows, reefs, or other foundational ecosystems during climate change depends on the discovery and use of individuals able to withstand future conditions. For coral reefs, climate-tolerant corals might not remain tolerant in different environments because of widespread environmental adjustment of coral physiology and symbionts. Here, we test if parent corals retain their heat tolerance in nursery settings, if simple proxies predict successful colonies, and if heat-tolerant corals suffer lower growth or survival in normal settings. Before the 2015 natural bleaching event in American Samoa, we set out 800 coral fragments from 80 colonies of four species selected by prior tests to have a range of intraspecific natural heat tolerance. After the event, nursery stock from heat-tolerant parents showed two to three times less bleaching across species than nursery stock from less tolerant parents. They also retained higher individual genetic diversity through the bleaching event than did less heat-tolerant corals. The three best proxies for thermal tolerance were response to experimental heat stress, location on the reef, and thermal microclimate. Molecular biomarkers were also predictive but were highly species specific. Colony genotype and symbiont genus played a similarly strong role in predicting bleaching. Combined, our results show that selecting for host and symbiont resilience produced a multispecies coral nursery that withstood multiple bleaching events, that proxies for thermal tolerance in restoration can work across species and be inexpensive, and that different coral clones within species reacted very differently to bleaching.

The coral settlement box: A simple device to produce coral stock from brooded coral larvae entirely in situ

Coral reef restoration requires efficient, effective and scalable techniques and methodologies to counteract the continued decline of coral reefs. Here we tested an in situ method to collect and settle fully developed planulae shed by the brooding coral species (Stylophora pistillata). Three devices called Coral Settlement Boxes (CSB; L × W × H: 50 × 40 × 6 cm; V: 4.5 L) were built from transparent Plexiglas and designed to be easily assembled and disassembled. Each CSB contained two integrated biofilm-covered nets (0.5 × 0.5 cm mesh size), which functioned as settlement substrate. The trap container of a traditional planulae trap was replaced by the CSB, and this new construction was used to collected planulae over 4 consecutive days. The CSBs were then transported to a mid-water coral nursery at 12 m depth. One CSB was disassembled immediately, the two settlement substrates were removed and each was placed in a protective cage (mesh size 4 cm2). The other two CSBs were opened after a 4-month period, leaving the four settlement substrates attached to the Plexiglas plates and covered by protective cages. None of the settlement substrates were cleaned of fouling organisms in the nursery. After 5 months in the mid-water nursery, a total of 120 healthy juvenile coral colonies had resulted from the estimated 2045 planulae initially trapped. This inexpensive and simple approach to producing sexually propagated stocks of colonies entirely in situ may enhance the efficiency, effectiveness and scalability of restoration activities that include brooding coral species.

Benefits of herbivorous fish outweigh costs of corallivory in coral nurseries placed close to a Kenyan patch reef

Coral mariculture involves time-consuming removal of fouling. On natural reefs, this service is provided by grazers. As natural reefs also harbour corallivores, it is debated whether reef-bound fish have a positive or negative effect on coral maricultured near natural reefs. This study quantified the net impact of herbivorous and corallivorous fish on coral mariculture. Nursery trees either uncaged, caged or as cage-control (15 per treatment) were placed near a patch reef at Wasini, Kenya, each hosting 10 Acropora verweyi fragments. From April to July 2016, survival and growth of the corals and bite marks on the corals were monitored. Using remote underwater video, bites by herbivorous and corallivorous fish were quantified. Upon termination of the experiment, dry weight of fouling from the nursery trees was determined. Caging of nurseries strongly reduced herbivory and corallivory. Results of cage-controls were not significantly different from uncaged trees. In caged nurseries, coral survival and growth were significantly lower than in uncaged nurseries, respectively 9% and 40% lower. Fouling was nearly 800% higher in caged nurseries. Herbivory was dominated by the surgeonfish Ctenochaetus striatus, which was responsible for 77% of the grazing. Monthly assessments showed bite marks on 10% of the uncaged coral fragments. Our study reveals that fouling control by herbivorous fish outweighs the costs of incidental corallivory on the survival and growth of A. verweyi. The vigour of unrestricted fouling, its negative impact on coral performance and the scarcity of corallivory justify the recommendation to place coral nurseries in Wasini near the reef.

Optimizing return‐on‐effort for coral nursery and outplanting practices to aid restoration of the Great Barrier Reef

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.

Books for budding scientists

From audacious space missions and quantum physics, to clean cookstoves and coral nurseries, this year's finalists for the AAAS/Suburu SB&F Prizes for Excellence in Science Books dare to go where few children's titles have gone before. Sponsored by Subaru of America and facilitated by the American Association for the Advancement of Science (AAAS, the publisher of Science ), the competition celebrates high-quality children's science books. Read on for reviews written by the staff of the Science family of journals and a few friends.

Genetic diversity of farmed and wild populations of the reef‐building coral, Acropora tenuis

Transplantation of nursery‐farmed corals is a primary management tool for restoration of degraded coral reefs. However, there have been concerns about the potential loss of genetic diversity in nurseries due to asexual propagation methods used to prepare transplants. Two coral nurseries at Maeganeku and Onna, Okinawa Island, Japan, furnish source material for regional restoration activities. Using 13 microsatellite markers, this study compared the genetic diversity of 132 Acropora tenuis colonies from these nurseries with that of 298 wild colonies from 15 sites across the Nansei Islands. Even though no clonal colonies were detected at wild sites, we estimated clonal richness of farmed corals to be 0.523 (Maeganeku) and 0.579 (Onna). Genotypic diversity is high in the nursery populations, 0.894 (Maeganeku) and 0.937 (Onna), but lower than in the natural populations (1.000). However, expected heterozygosity did not differ significantly between locations, including the coral nurseries (one‐way analysis of variance, p > 0.05). Inbreeding coefficients of nursery populations (Onna, −0.019 to Maeganeku, 0.097) fell within the range of estimates from wild populations (Sesoko, −0.058 to Maeda, 0.278). Furthermore, based on Structure analysis, farmed A. tenuis comprises the same genetic population that occupies the surrounding natural area. Thus, given no additional statistically significant increase of clonal colonies within nurseries, using farmed coral assemblages for reef restoration may be preferable to transplanting and damaging wild assemblages. Coral gametes of farmed colonies may also be used to produce coral larvae for transplantation of sexually propagated corals.

First record of cuttlefish egg-deposition at an <i>in situ</i> coral nursery

First record of cuttlefish egg-deposition at an <i>in situ</i> coral nursery

Coral nursery and transplantation of the staghorn coral, Acropora downingi in Sabah Al-Ahmad Sea City, Kuwait, Arabian Gulf

The present work describes the first attempt at cultivating corals in the northern Arabian Gulf where seawater temperature ranges from 13 to 33°C and salinity exceeds 40 psu, exceeding normal letha...