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Coral Reef Restoration as a strategy to improve ecosystem services: A guide to coral restoration methods
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With accelerating declines of coral reefs globally and the start of the UN Decade on Ecosystem Restoration, the need for better understanding the effectiveness of coral reef restoration efforts, particularly in supporting the maintenance of ecosystem services, is accelerating. This document presents an overview of the best-available knowledge in the field and provides realistic recommendations for the use of restoration as a management strategy for coral reefs to assist managers, practitioners, policy makers, and funding agencies to make informed decisions.
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... Corals are threatened by anthropogenic impacts, such as land-use change (urban, industrial and agricultural), nutrient enrichment, chemical and noise pollution, resource exploitation, damage from fishing gear and destructive fishing activity, invasive species, disease, and declining water quality (Souter et al. 2021). Climate change and increasing levels of atmospheric greenhouse gases continue to have serious direct and indirect effects, including ocean acidification, more frequent bleaching events and increasing frequency and intensity of storms (Hein et al. 2020). The Status of the Coral Reefs of the World 2020 report, by the Global Coral Reef Monitoring Network (GCRMN) reported that between 2009 and 2018 there was a loss of 14% of the global average cover of stony (hard) coral on the world's coral reefs (Souter et al. 2021). ...
... As coral colonies can take many years or even centuries to recover from damage (Boch et al. 2019), the priority should be effective measures to protect existing reefs, and colonies, followed by measures to mitigate anthropogenic impacts and threats. Restoration should work in conjunction with protection and mitigation (Montero-Serra et al. 2019;Boström-Einarsson et al. 2020;Souter et al. 2021). All these measures must be combined with global efforts to tackle climate change and reduce the devastating impact on the world's corals such as a rise in ocean temperature and increased ocean acidification, as well as the equally deleterious impacts of excess nutrient input and eutrophication (Silbiger et al. 2018). ...
... Marine Protected Areas) have been carried out (e.g. Pendleton et al. 2018;Montero-Serra et al. 2018, NASEM 2019, Boström-Einarsson et al. 2020. However, the evidence for the effectiveness of all actions targeting coral conservation or reef restoration has not yet been synthesized and assessed under a formal review. ...
Coral Conservation: Global evidence for the effects of actions provides an essential resource for anyone dedicated to conserving or restoring corals. This comprehensive synthesis of global scientific evidence examines the effectiveness of conservation and restoration actions targeting stony, soft and cold-water coral species inhabiting a diverse range of marine habitats in tropical, temperate and arctic waters from shallow coasts to the deep sea.
Addressing the urgent threats posed by climate change, invasive species, overfishing, and habitat destruction, this work summarizes evidence from actions in three core themes: protecting healthy reefs, mitigating human impacts, and undertaking active restoration. From establishing Marine Protected Areas to innovative techniques like coral gardening, the synopsis summarizes the evidence for practical actions and offers insights into their outcomes and applicability.
Designed to guide decision-makers—resource managers, conservationists, policymakers, and local advocates—as well as those curious to learn about actions that could help corals, this accessible guide provides succinct information to support evidence-based conservation.
By identifying the existing evidence and highlighting gaps in the knowledge, Coral Conservation can support practitioners and policymakers to allocate resources effectively by prioritising actions that work. By doing more of what works, we can reverse the loss of coral species and restore these vital habitats for the benefit of current and future generations.
The authors consulted an international group of coral experts and conservationists to produce this synopsis. Funding was provided by A.G. Leventis Foundation and Oceankind.
Coral Conservation is the 25th publication in the Conservation Evidence Series Synopses, and is freely available from the online Conservation Evidence database (www.conservationevidence.com) ensuring that users have ongoing access to updated research and assessments. Others in the series include Eel Conservation in Inland Habitats, Biodiversity of Marine Artificial Structures, Sub-tidal Benthic Invertebrate Conservation, Marine and Freshwater Mammal Conservation, and Marine Fish Conservation.
... To increase the growth rate of coral communities, we consider it effective to install structures in areas with moderate waves and currents, to provide water channels through the structures, to increase the shallow area and effective slope of the cross-sectional shape, and to include surface processing on surfaces in locations with favorable environments for coral colonization. Table 2 summarizes the challenges of restoring coral habitats by using artificial structures, and recommendations from this study, focusing on three criteria-efficiency, cost, and scalability-presented by Hein et al. 5 . ...
... For example, the cost-effectiveness of restoring coral communities in ATPs by utilizing the shallow areas of breakwaters is comparable to that of transplantation in developed countries 31 . The use of artificial structures also helps to Criteria coming from Hein et al. 5 Challenges suggested by this and previous studies Implications from this study Efficiency ⋅Limited evidence of success linked to structures being overgrown by corals 5 ...
... For example, the cost-effectiveness of restoring coral communities in ATPs by utilizing the shallow areas of breakwaters is comparable to that of transplantation in developed countries 31 . The use of artificial structures also helps to Criteria coming from Hein et al. 5 Challenges suggested by this and previous studies Implications from this study Efficiency ⋅Limited evidence of success linked to structures being overgrown by corals 5 ...
Rising seawater temperatures from climate change have caused coral bleaching, risking coral extinction by century’s end. To save corals, reef restoration must occur alongside other climate-change mitigation. Here we show the effectiveness of habitat creation on artificial structures for rapid coral restoration in response to climate change. We use 29 years of field observations for coral distributions on breakwaters and surrounding reefs (around 33,000 measurements in total). Following bleaching in 1998, breakwaters had higher coral cover (mainly Acropora spp.) than did surrounding natural reefs. Coral recovery times on breakwaters matched the frequency of recent bleaching events (~ every 6 years) and were accelerated by surface processing of the artificial structures with grooves. Corals on breakwaters were more abundant in shallow waters, under high light, and on moderately sloped substrate. Coral abundance on breakwaters was increased by incorporating shallow areas and surface texture. Our results suggest that habitat creation on artificial structures can increase coral community resilience against climate change by increasing coral recovery potential.
... Efforts to restore coral reefs are accelerating worldwide as local and global anthropogenic pressures continue to erode coral reef ecosystems . Management strategies increasingly incorporate stewardship-led restoration activities (e.g., Hein et al. 2020;Shaver et al. 2020;Suggett et al. 2023) that are often coupled to research and development portfolios spanning fundamental science and engineering (e.g., Bay et al. 2023;Voolstra et al. 2021) to recover degraded reef sites. In parallel, financing and commercialization mechanisms to support and scale these restoration activities have diversified (Suggett et al. 2023) and the number of restoration projects around the world has rapidly grown. ...
... In parallel, financing and commercialization mechanisms to support and scale these restoration activities have diversified (Suggett et al. 2023) and the number of restoration projects around the world has rapidly grown. While reef restoration activities continue to expand in approach, location, socio-ecological context, and expertise (e.g., Boström-Einarsson et al. 2020;Hein et al. 2020Hein et al. , 2021Suggett et al. 2023;Peixoto et al. 2024), the vocabulary now used to describe restoration activities and practices has evolved to the point where new (and not-so-new) to-thefield practitioners, scientists, policy makers, communicators, and investors must navigate an increasingly confusing set of Abstract Global coral reef restoration efforts continue to diversify in approach, location, and socio-ecological context. In parallel, vocabulary has evolved such that practitioners, scientists, policy makers, communicators, and investors must navigate an increasingly confusing set of terms that are inconsistently defined. ...
... Core processes form the framework for common "reef restoration workflows" (sensu Hein et al. 2020, specifically, coral propagation using either in-water (in situ) or land-based (ex situ) nurseries and subsequent coral planting, the latter of which may involve substrate preparation steps such as removal of space competitors (e.g., macroalgae, farming damselfish) and predators (e.g., Drupella snails) or substrate stabilization and addition (Table 3). Collectively, the common restoration workflow describes the core practice of coral restoration (or gardening) via both pro-and re-active restoration (Hein et al. 2021) and "biological support to accelerate natural reef recovery" (Bay et al. 2019) (Table 1), with the respective key terms and definitions in Table 3. ...
Global coral reef restoration efforts continue to diversify in approach, location, and socio-ecological context. In parallel, vocabulary has evolved such that practitioners, scientists, policy makers, communicators, and investors must navigate an increasingly confusing set of terms that are inconsistently defined. Precision around terms and definitions is an important attribute underpinning the rate and extent with which restoration can scale. However, in contrast with more established ecological restoration fields, coral reef restoration lacks a formal lexicon for its core approaches and processes. Here we synthesize, distill, and clarify a core lexicon proposed for coral reef restoration. We navigate readers systematically through terms used for various coral reef restoration approaches, project planning and intent, process workflows, and biological material. We also consider vague terms commonly used that present challenges to singularly define. While we expect this proposed lexicon to continue to evolve, we offer an important first step toward more integrated communications around coral reef restoration.
... Below (3.1-3.6), we discuss the most important manners in which biodiversity can be mischaracterised and its effects on conservation and restoration (see also Chenuil et al. (2019) for similar discussions). We also identify ways in which cryptic taxa and hybridisation could potentially aid restoration (3.5). Figure 5 outlines some possible consequences of cryptic coral taxa to current restoration actions such as direct transplantation and coral gardening (Rinkevich, 1995) and other actions that are being actively researched for managing coral populations to improve their resilience to climate change (National Academies of Sciences, 2019; Anthony et al., 2020;Hein et al., 2020;Bay et al., 2023). ...
... Figure 5 -How cryptic coral taxa and hybridisation could affect coral reef restoration actions that aim to preserve biological diversity, counter population declines, and/or promote resilience to climate change through biological adaptation. Terminologies follow National Academies of Sciences, 2019;Hein et al., 2020;Bay et al., 2023) and are not mutually exclusive. For example, assisted movement could be undertaken on fragments (direct transplantation), larvae, or via the progeny of captive, sexually propagated corals. ...
The conservation and management of coral reef ecosystems will benefit from accurate assessments of reef-building coral species diversity. However, the true diversity of corals may be obfuscated by cryptic yet genetically distinct groups, which are likely more pervasive than currently recognised. Here, we investigate the prevalence of cryptic coral groups and assess evidence for their permeability to gene flow (hybridisation) via a structured literature review of genomic studies. Using reproducible criteria to detect distinct genetic groups that are sympatric, we find that 68% of nominal species represented in population genomic studies show evidence for comprising partially reproductively isolated groups and that these distinct groups are often linked by gene flow. Cryptic genetic groups frequently segregate by environment, especially depth, and may differ by phenotypic characteristics including resilience to heat stress. This hidden biodiversity creates challenges for coral conservation and restoration planning that are not well appreciated, including hiding true population declines, biasing estimates for species’ phenotypic breadth, overestimating the resilience of species to stressors, yielding uncertainty in evolutionary dynamics inferred from past studies, and implying that reproductive barriers may limit mating between local and translocated corals. Incorporating the expectation that coral cryptic taxa with incomplete species boundaries will frequently be encountered is critical to the long-term success of coral conservation and restoration programs. Studying these phenomena in more detail will directly benefit conservation and restoration goals. Thus, we detail recommendations for best practice and strategies for identifying cryptic taxa and hybridisation. In addition, cryptic coral taxa present an untapped resource for studying speciation which could provide rich opportunities for collaboration among coral and speciation biologists and fill key knowledge gaps relevant to conservation and restoration.
... Active reef rehabilitation has only gradually become accepted by the scientific community as a credible conservation tool and therefore ample opportunities remain to improve this management intervention [3,4]. A commonly-used rehabilitation method is coral gardening, where coral fragments are grown in nurseries before being outplanted onto degraded or artificial reefs [5,6]. While coral gardening has been shown to improve coral cover and reef biodiversity locally [7,8], there remain concerns about the feasibility and costs of upscaling this labour-intensive method [9]. ...
Restoration and artificial reefs can assist the recovery of degraded reefs but are limited in scalability and climate resilience. The Mineral Accretion Technique (MAT) subjects metal artificial reefs to a low-voltage electrical current, thereby creating a calcium-carbonate coating. It has been suggested that corals on MAT structures experience enhanced health and growth. However, prior studies report conflicting results potentially due to different conditions, species and approaches used. We investigated how MAT influences the bleaching resilience, condition and growth of four coral species and natural coral recruitment in Kenya. Coral fragments were outplanted on charged iron tables using commonly-applied settings (6 V; 0.84 A m⁻²). After one month, when all tables had acquired a calcium-carbonate coating, half of the tables were taken off electricity to serve as controls. Both treatments (MAT and Control) were monitored on coral brightness, condition (live tissue cover), growth and natural recruitment for one year, during which a marine heatwave occurred. Coral bleaching was significantly more severe on MAT for all studied species. For three species, coral condition dropped sharply during the heatwave and this decline was faster and more severe on MAT. Coral growth was reduced during the heatwave for all corals and remained low for one species on MAT. After one year, the Control harboured 34 coral recruits, whereas none were found on MAT. Thus, while MAT can be useful to prevent corrosion of metal artificial reefs, we do not recommend MAT as reported here to improve coral growth, condition, heat resilience or recruitment.
... Over the last years, several methods have been developed and applied with varying levels of success. Here, the term restoration describes a suite of interventions aimed at improving reef structure, ecosystem function and increasing populations of key species in areas that have been damaged (see Hein et al. 2020). Some reef restoration strategies were initially adapted from methods used in the terrestrial ecosystems, as the concept of transplantation and coral gardening developed in the 1990s (Rinkevich 1995). ...
This chapter focuses on discussing the main strategies for the conservation and management of Brazilian reefs. Marine Protected Areas (MPAs) are one of the key components of reef conservation. Although the existing system of MPAs covers 15.3% of the total reef area, the reality of this figure is misleading because only a fraction of reef habitats is covered by no-take MPAs (3.6%), and several reef types have no coverage by fully-protected MPAs. Discrepancies between the amount of coverage by all MPAs and what is covered by no-take ones were stronger on the Northeastern continental shelf and decreased towards oceanic, deep reef areas, thus confirming the strong protection bias. Existing system of MPAs also does not meet the minimum requirements to adequately protect threatened species, particularly the endemic ones. The predominance of multiple-use MPAs highlights critical gaps between MPA coverage and protection levels afforded. The conservation effectiveness of Brazilian MPAs is variable and the difference between MPA coverage and protection level reached up to 94%. The extensive amount of reef area lying within priority areas for further protection highlights the need of expanding and strengthening the existing system of MPAs. We also identified a general lack of long-term monitoring programs running over no-take MPAs and the absence of more specific studies developing recovery tools designed for coral reefs.
... The sheer number of projects and diversity of organisations involved in Indonesian coral reef restoration presents various challenges for standardisation. Current efforts are hampered by mismatches between programme objectives and assessment metrics used (Hein et al. 2020b); selecting appropriate metrics enables more rigorous assessments of performance and the employment of adaptive strategies to improve efficacy. There remains a widespread lack of effective ecological monitoring and consistent reporting: only 16% of projects since 1990 have incorporated a post-installation monitoring programme to gauge ecological responses to restoration . ...
Indonesia is the global coral reef restoration leader by number of projects, yet these remain diverse and disparate. This study reviews the status of Indonesian coral reef restoration within a framework of international common best practice (CBP) that incorporates internationally-recognised Standards for Ecological Restoration (SER). This framework is used to formulate recommendations for a formal network of reef restoration practitioners with the purview to develop and implement a national restoration roadmap. Forty-five projects were surveyed to determine how projects have been planned and implemented. This was compared with recommendations from CBP. There is particular scope to increase quantitative data collection, reinforce community involvement, improve ecological data collection, and standardise monitoring protocols. While 84% of projects reported quantifiable goals, 64% did not quantify goals during planning and 61% did not incorporate climate-smart design features. Quantitative reef monitoring surveys were absent in 22% of projects. The majority of projects did not quantify important ecological metrics like coral community composition/diversity (96%), coral health/bleaching (89%), benthic community (62%), and coral survival (62%). Indonesia has the capacity, regulations, and networks to position itself as a reef restoration driver in the Coral Triangle region; this will require increased coordination, alignment, and quantification of restoration. A structured, collaborative, and iterative national network of various stakeholders would facilitate the development of a national restoration roadmap based on adaptive management strategies. This would aid in standardising project planning, monitoring, and reporting. Efforts should include an increased focus on climate change adaptation goals.
... The practice of coral reef restoration broadly describes any active conservation intervention designed to assist or accelerate the recovery of coral populations and associated reef structure, function and ecosystem services (Hein et al. 2021a). Despite decades of research and practice, there are only a handful of case studies showing promising outcomes (Williams et al. 2019;Hein et al. 2021b;Peterson et al 2023). This is partly due to a lack of systematic long-term monitoring of restoration projects, but there has also been a focus on methods that can be applied at sub-hectare scales (e.g., reattaching corals of opportunity) and on certain coral taxa and life histories (primarily fast-growing branching species) (Boström-Einarsson et al. 2020;Ferse et al. 2021). ...
Efforts to restore coral reefs usually involve transplanting asexually propagated fast-growing corals. However, this approach can lead to outplanted populations with low genotypic diversity, composed of taxa susceptible to stressors such as marine heatwaves. Sexual coral propagation leads to greater genotypic diversity, and using slow-growing, stress-tolerant taxa may provide a longer-term return on restoration efforts due to higher outplant survival. However, there have been no reports to date detailing the full cycle of rearing stress-tolerant, slow-growing corals from eggs until sexual maturity. Here, we sexually propagated and transplanted two massive slow-growing coral species to examine long-term success as part of reef restoration efforts. Coral spat were settled on artificial substrates and reared in nurseries for approximately two years, before being outplanted and monitored for survivorship and growth for a further four years. More than half of initially settled substrates supported a living coral following nursery rearing, and survivorship was also high following outplantation with yields declining by just 10 to 14% over four years. At 6-years post-fertilisation over 90% of outplanted corals were reproductively mature, demonstrating the feasibility of restoring populations of sexually mature massive corals in under a decade. Although use of slower growing, stress tolerant corals for reef restoration may provide a longer-term return on investment due to high post-transplantation survival rates, considerable time is required to achieve even modest gains in coral cover due to their relatively slow rates of growth. This highlights the need to use a mix of species with a range of life-history traits in reef restoration and to improve survivorship of susceptible fast-growing taxa that can generate rapid increases in coral cover.
Coral Conservation: Global evidence for the effects of actions provides an essential resource for anyone dedicated to conserving or restoring corals. This comprehensive synthesis of global scientific evidence examines the effectiveness of conservation and restoration actions targeting stony, soft and cold-water coral species inhabiting a diverse range of marine habitats in tropical, temperate and arctic waters from shallow coasts to the deep sea.
Addressing the urgent threats posed by climate change, invasive species, overfishing, and habitat destruction, this work summarizes evidence from actions in three core themes: protecting healthy reefs, mitigating human impacts, and undertaking active restoration. From establishing Marine Protected Areas to innovative techniques like coral gardening, the synopsis summarizes the evidence for practical actions and offers insights into their outcomes and applicability.
Designed to guide decision-makers—resource managers, conservationists, policymakers, and local advocates—as well as those curious to learn about actions that could help corals, this accessible guide provides succinct information to support evidence-based conservation.
By identifying the existing evidence and highlighting gaps in the knowledge, Coral Conservation can support practitioners and policymakers to allocate resources effectively by prioritising actions that work. By doing more of what works, we can reverse the loss of coral species and restore these vital habitats for the benefit of current and future generations.
The authors consulted an international group of coral experts and conservationists to produce this synopsis. Funding was provided by A.G. Leventis Foundation and Oceankind.
Coral Conservation is the 25th publication in the Conservation Evidence Series Synopses, and is freely available from the online Conservation Evidence database (www.conservationevidence.com) ensuring that users have ongoing access to updated research and assessments. Others in the series include Eel Conservation in Inland Habitats, Biodiversity of Marine Artificial Structures, Sub-tidal Benthic Invertebrate Conservation, Marine and Freshwater Mammal Conservation, and Marine Fish Conservation.
Climate change is impacting coral reefs now. Recent pan-tropical bleaching events driven by unprecedented global heat waves have shifted the playing field for coral reef management and policy. While best-practice conventional management remains essential, it may no longer be enough to sustain coral reefs under continued climate change. Nor will climate change mitigation be sufficient on its own. Committed warming and projected reef decline means solutions must involve a portfolio of mitigation, best-practice conventional management and coordinated restoration and adaptation measures involving new and perhaps radical interventions, including local and regional cooling and shading, assisted coral evolution, assisted gene flow, and measures to support and enhance coral recruitment. We propose that proactive research and development to expand the reef management toolbox fast but safely, combined with expedient trialling of promising interventions is now urgently needed, whatever emissions trajectory the world follows. We discuss the challenges and opportunities of embracing new interventions in a race against time, including their risks and uncertainties. Ultimately, solutions to the climate challenge for coral reefs will require consideration of what society wants, what can be achieved technically and economically, and what opportunities we have for action in a rapidly closing window. Finding solutions that work for coral reefs and people will require exceptional levels of coordination of science, management and policy, and open engagement with society. It will also require compromise, because reefs will change under climate change despite our best interventions. We argue that being clear about society’s priorities, and understanding both the opportunities and risks that come with an expanded toolset, can help us make the most of a challenging situation. We offer a conceptual model to help reef managers frame decision problems and objectives, and to guide effective strategy choices in the face of complexity and uncertainty.
Active restoration is becoming an increasingly important conservation intervention to counteract the degradation of marine coastal ecosystems. Understanding what has motivated the scientific community to research the restoration of marine coastal ecosystems and how restoration research projects are funded is essential if we want to scale-up restoration interventions to meaningful extents. Here, we systematically review and synthesize data to understand the motivations for research on the restoration of coral reefs, seagrass, mangroves, saltmarsh, and oyster reefs. We base this analysis off a published database of marine restoration studies, originally designed to estimate the cost and feasibility of marine coastal restoration, derived from mostly scientific studies published in peer-reviewed and some gray literature. For the present study, the database was updated with fields aimed at assessing the motivations, outcomes, and funding sources for each project. We classify restoration motivations into five categories: biotic, experimental, idealistic, legislative, and pragmatic. Moreover, we evaluate the variables measured and outcomes reported by the researchers and evaluate whether projects adhered to the Society for Ecological Restoration's (SER) standards for the practice of ecological restoration. The most common motivation of the scientific community to study restoration in marine coastal ecosystems was experimental i.e., to seek experimental data to answer ecological research questions or improve restoration approach, as expected since mostly peer-reviewed literature was evaluated here. There were differences in motivations among the five coastal ecosystems. For instance, biodiversity enhancement was the most common case for a biotic motivation in mangrove restoration projects. The most common metrics evaluated were growth/productivity, survivorship, habitat function, physical attributes, and reproduction. For most ecosystems, ecological outcomes were frequently reported, with socio-economic implications of the restoration rarely mentioned, except for mangroves. Projects were largely funded by governmental grants with some investment from private donations, non-governmental organizations, and the involvement of volunteers. Our findings and database provide critical data to align future research of the scientific community with the real social, economic and policy needs required to scale-up marine coastal restoration projects.
The accelerating marks of climate change on coral-reef ecosystems, combined with the recognition that traditional management measures are not efficient enough to cope with climate change tempo and human footprints, have raised a need for new approaches to reef restoration. The most widely used approach is the “coral gardening” tenet; an active reef restoration tactic based on principles, concepts, and theories used in silviculture. During the relatively short period since its inception, the gardening approach has been tested globally in a wide range of reef sites, and on about 100 coral species, utilizing hundreds of thousands of nursery-raised coral colonies. While still lacking credibility for simulating restoration scenarios under forecasted climate change impacts, and with a limited adaptation toolkit used in the gardening approach, it is still deficient. Therefore, novel restoration avenues have recently been suggested and devised, and some have already been tested, primarily in the laboratory. Here, I describe seven classes of such novel avenues and tools, which include the improved gardening methodologies, ecological engineering approaches, assisted migration/colonization, assisted genetics/evolution, assisted microbiome, coral epigenetics, and coral chimerism. These are further classified into three operation levels, each dependent on the success of the former level. Altogether, the seven approaches and the three operation levels represent a unified active reef restoration toolbox, under the umbrella of the gardening tenet, focusing on the enhancement of coral resilience and adaptation in a changing world.
Tropical reef systems are transitioning to a new era in which the interval between
recurrent bouts of coral bleaching is too short for a full recovery of mature
assemblages. We analyzed bleaching records at 100 globally distributed reef locations
from 1980 to 2016. The median return time between pairs of severe bleaching events
has diminished steadily since 1980 and is now only 6 years. As global warming has
progressed, tropical sea surface temperatures are warmer now during current La Niña
conditions than they were during El Niño events three decades ago. Consequently,
as we transition to the Anthropocene, coral bleaching is occurring more frequently in all
El Niño–Southern Oscillation phases, increasing the likelihood of annual bleaching in
the coming decades.
Over the last decades worldwide, coral reef degradation and the failures of the traditional management approaches have raised the need for innovative active reef restoration approaches in order to accelerate local, regional, and global-scale solutions to this pressing ecological calamity. The coral gardening notion, a two-phase practice adapted from forestation principles and methodologies, has been applied at a small scale in a highly degraded reef site in Eilat (Red Sea, Israel), in an attempt to test the long-term impact of repeated trans-plantation measures as a novel coral reef restoration tool. Nursery-bred colonies of seven locally common branching species (Stylophora pistillata, Pocillopora damicornis, Acropora variabilis, A. humilis, A. pharaonis, A. valida, Millepora dichotoma) and one massive species (Dipsastraea favus) were transplanted during three transplantation sessions (1.5 year intervals) onto six denuded coral knolls. The 1,400 farmed transplants were secured to the knolls using an underwater drilling methodology that increased transplantation efficiency, as compared to gluing/cementing approaches, and enabled the transplantation on vertical facets for maximum coverage of the target area. Over six years of in situ detailed monitoring and almost 15 years prospectus from initiation, revealed the capacity of nursery-bred transplants to acclimate and thrive in the new environment of a degraded reef. First, no signs of stress that could be related to the relocation of coral colonies from the protective coral nursery into the degraded site were observed, and over the long term, the nursery-bred transplants had slightly lower survival rates than the highly adapted, naturally growing colonies at the experimental site. Preliminary results suggest that repeated transplantations (i.e., adding transplants onto plots upon which coral transplants are already present) may enhance transplant survival. Despite the new challenging conditions of the degraded reef area, the farmed transplants continued to grow at enhanced rates, characteristic of those recorded in the coral nursery. Additionally, S. pistillata transplants exhibited higher reproductive capacities than the (continued)
The world's coral reefs are rapidly transforming, with decreasing coral cover and new species configurations. These new Anthropocene reefs pose a challenge for conservation; we can no longer rely on established management plans and actions designed to maintain the status quo when coral reef habitats, and the challenges they faced, were very different. The key questions now are: what do we want to conserve on Anthropocene reefs, why, and how? Trends in reef management over recent decades reveal rapid shifts in perceived threats, goals and solutions. Future reefs will be unlike anything previously seen by humans, and while their ability to support tourism or fisheries may be relatively resilient, our capacity to manage them may be constrained by their new species configurations. Furthermore, there is a growing spatial mismatch between the escalating scale of threats and current or planned responses. We present a blueprint for future reef conservation that recognizes the need to better understand the processes that maintain Anthropocene reefs, and the growing imperative to reform conservation efforts to address both specific local issues and larger-scale threats. The future of coral reef conservation is no longer one solely of localized action and stewardship; it requires practices and institutions operating at far larger scales than today.
Coral reef restoration is an increasingly important part of tropical marine conservation. Information about what motivates coral reef restoration as well as its success and cost is not well understood but needed to inform restoration decisions. We systematically review and synthesise data from mostly scientific studies published in peer‐reviewed and grey literature on the motivations for coral reef restoration, the variables measured, outcomes reported, the cost per hectare of the restoration project, the survival of restored corals, the duration of the project and its overall spatial extent depending on the restoration technique employed. The main motivation to restore coral reefs for the projects assessed was to further our ecological knowledge and improve restoration techniques, with coral growth, productivity and survival being the main variables measured. The median project cost was 400,000 US), ranging from 6,000 US ha‐1 for substrate addition to build an artificial reef. Restoration projects were mostly of short duration (1‐2 years) and over small spatial extents (0.01 ha or 108 m²). Median reported survival of restored corals was 60.9%. Future research to survey practitioners who do not publish their discoveries would complement this work. Our findings and database provide critical data to inform future research in coral reef restoration.
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The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides regular assessments of the scientific basis of climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report is a comprehensive assessment of our understanding of global warming of 1.5°C, future climate change, potential impacts and associated risks, emission pathways, and system transitions consistent with 1.5°C global warming, and strengthening the global response to climate change in the context of sustainable development and efforts to eradicate poverty. It serves policymakers, decision makers, stakeholders and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.
Coral nursery and out‐planting 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 critical to the cost‐effectiveness and viability of restoration programs. In many cases, return‐on‐effort 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 return‐on‐effort (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 amongst 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 out‐planting) efforts.
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Incorporating ecological processes into restoration planning is increasingly recognized as a fundamental component of successful restoration strategies. We outline a scientific framework to advance the emerging field of coral restoration. We advocate for harnessing ecological processes that drive community dynamics on coral reefs in a way that facilitates the establishment and growth of restored corals. Drawing on decades of coral reef ecology research and lessons learned from the restoration of other ecosystems, we posit that restoration practitioners can control factors such as the density, diversity, and identity of transplanted corals; site selection; and transplant design to restore positive feedback processes-or to disrupt negative feedback processes-in order to improve restoration success. Ultimately, we argue that coral restoration should explicitly incorporate key natural processes to exploit dynamic ecological forces and drive recovery of coral reef ecosystems.