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Coastal habitat restoration, especially of coral reef ecosystems, can significantly reduce the exposure of coastal communities to natural hazards and, consequently, the risk of wave-driven flooding. Likewise, reef degradation can increase coastal flood risks to people and property. In this study, the valuation of coral reefs in the United States Virgin Islands (USVI), along the coasts of St. Croix, St. John, and St. Thomas, demonstrated the social and economic benefits provided by these natural defenses. Across the territory, more than 481 people and $31.2 million of infrastructure were estimated to receive protection from coral reefs per year (2010 U.S. dollars). In 2017, Hurricanes Irma and Maria significantly damaged coral reefs throughout the archipelago. By combining engineering, ecological, geospatial, social, and economic data and tools, this study provided a rigorous valuation of where potential coral reef restoration projects could help rebuild these damaged habitats and decrease the risks from coastal hazards faced by USVI’s reef-fronted communities. Multiple restoration scenarios were considered in the analysis, two of which are detailed in this report. These include (1) ‘Ecological’ restoration, where restoration creates a structure that is 0.25 m high and 25-m-wide reef, and (2) ‘Hybrid’ restoration, where restoration creates a structure that is 1.25 m high and 5 m wide. There are many ways that such structures could be developed. In the hydrodynamic analyses, there are no assumptions about how the restoration is developed. Many practitioners of both coral (and oyster reef) restoration consider that a reef height of 0.25 m might be delivered from planting corals alone and that 1.25 m might require a combination of artificial structures and coral planting. In a third scenario, the analysis investigated the reduction of protection benefits that would occur through the reduction of 1 meter of naturally occurring reef height due to reef degradation. The reduction of protection due to the loss of reefs can also be interpreted as the protection value of the existing reefs. In all studied restoration scenarios, it was assumed that the planting of corals would enhance hydrodynamic roughness, effectively dissipating incident wave energy and reducing the potential for coastal flooding. A standardized approach was employed to strategically locate potential restoration projects along the entire linear extent of existing reefs bordering the USVI, and to identify where coral reef restoration could offer valuable benefits in flood reduction. Potential restoration projects were only located within the existing distribution of reefs across the region, even though numerous sites were positioned far offshore (2-3 km), and some were at relatively deep depths (up to 7 m). Risk-based valuation approaches were followed to delineate flood zones at a 10 m2 resolution along the entire region's reef-lined shorelines for all the potential coral reef restoration scenarios. These were subsequently compared to flood zones without coral reef restoration. The potential reduction in coastal flood risk provided by coral reef restoration, and the protection value of existing reefs, were quantified utilizing the latest information available at the time of analysis from the U.S. Census Bureau, Federal Emergency Management Agency (FEMA), and Bureau of Economic Analysis for return-interval storm events. The change in Expected Annual Damages (EAD), a metric indicating the annual protection gained due to coral reef restoration, was calculated based on the damages associated with each storm probability. The findings suggest that the benefits of reef restoration are spatially variable within the USVI. In some areas, the analysis showed limited benefits from reef restoration, which may be attributed to the depth or offshore distances of proposed restoration sites. However, there were a number of key areas where reef restoration could have substantial benefits for flood risk reduction. The annual flood risk reduction attributed to potential ‘ecological’ coral reef restoration in the USVI was 99 people and $6.1 million (2010 U.S. dollars). The Benefit-to-Cost Ratio (BCR) for this restoration approach was found to be larger than 1 (i.e., cost-effective) along 11% of the St. Croix coastline, 4.9% of the St. John coastline, and 8.7% of the St. Thomas coastline. This analysis offers stakeholders and decision-makers a spatially explicit and rigorous evaluation that illustrates how, where, and when potential coral reef restoration efforts in St. Croix, St. John, and St. Thomas could be instrumental to reducing coastal storm-induced flooding. Understanding areas where reef management, recovery, and restoration could effectively reduce climate hazard-related risks is crucial to protect and enhance the resilience of coastal communities in USVI.

Corals and gorgonians play an important role as ecosystem engineers in many sublittoral communities worldwide. However, coral populations are being increasingly impacted by human activities. Active ecological restoration is a popular conservation tool nowadays, widely used to revert degradation in natural populations. Several studies have reported survival and growth success in actively restored corals, but few have studied the long‐term effect of transplantation on coral reproduction. We investigated survival and sexual reproduction of transplanted colonies of the Mediterranean gorgonian Eunicella singularis up to 3 years after being recovered from fishery bycatch and transplanted back to their habitat. Three different colony sizes were tested to explore possible effects of fragmentation on survival and reproduction. Results showed that transplanted colonies suffered a significant mortality during the first 4–5 months (30–35%), independently of fragment size. However, larger fragments showed high survival despite other disturbances, as a bloom of ephemerons filamentous algae occurred during the study. Results also showed that reproductive capacity is negatively affected by transplantation in female colonies. Conversely, male colonies were not directly affected by transplantation but showed an unexpectedly reduced number of spermary sacs both in transplanted and natural control colonies. The trade‐off between investment in reproduction and mortality of transplants highlights that large colony size could be the most appropriate for the active restoration of E. singularis. This study emphasizes the need to explore the long‐term viability and the reproduction investment in transplanted corals as indicators of restoration success, whose populations are sustained by sexual reproduction. [ABSTRACT FROM AUTHOR]

Caribbean coral reefs face unprecedented decline due to anthropogenic and environmental stressors, necessitating active restoration efforts. Among the strategies to conserve and restore reef ecosystems, land‐based sexual propagation of corals is crucial for preserving genetic diversity and population resilience. This study explores the efficacy of utilizing native sea urchin herbivory to control benthic macroalgal proliferation and enhance coral growth in land‐based propagation systems. Three captive‐reared urchin species—Lytechinus variegatus, Tripneustes ventricosus, and Diadema antillarum—were evaluated for their influence on algal cover and growth of sexually propagated brain coral Pseudodiploria strigosa. Juveniles of each urchin species were co‐cultured with 6‐month‐old coral colonies over a 105‐day experiment. Results indicated that all urchin treatments effectively reduced algal cover compared to controls; however, only T. ventricosus significantly increased coral growth rate, while the other urchin species did not have a notable effect. Despite differences in growth, coral survival was consistently high across all treatments. Benthic community analysis revealed shifts in algal composition, with D. antillarum grazing associated with increased crustose coralline algae. However, overgrazing by D. antillarum may have resulted in mild peripheral tissue damage to some corals. Urchin survival remained high, suggesting potential for downstream utilization in restoration (e.g. urchin population enhancement). This study highlights the potential of native urchins as biocontrol agents in coral propagation, emphasizing the importance of species‐specific interactions in shaping benthic communities and promoting coral resilience. [ABSTRACT FROM AUTHOR]

ABSTRACT Coral reef ecosystems support high fish biodiversity through ecological interactions with structural complexity across multiple spatial scales including coral colony architecture and the surrounding seascape structure. In an era where the complexity of coral reef ecosystems is being diminished, understanding the importance of structural characteristics beyond single focal patches has the potential to better inform actions for protecting, restoring or creating habitat for reef‐associated species. A seascape ecology approach was applied to explore the associations between multiple scales of seascape structure and fish assemblage response variables within a small (49.6 km2) offshore no‐take MPA, Sir Bu Nair Island Protected Area, in Sharjah, United Arab Emirates. Fish–seascape associations were modelled with single regression trees. Both in situ and remote sensing–derived variables produced the best models with highest contributions from coral cover, amount of hard‐bottom habitat type and structural complexity of the seafloor terrain. Fish species richness was significantly higher where coral cover exceeded 35%. The hard‐bottom areas with coral supported diverse assemblages dominated by carnivorous and omnivorous fishes. The Sir Bu Nair Island Protected Area provides a critical refuge for threatened and regionally overexploited species including those with low resilience to fishing. The ecological success of this protected area is key to safeguarding regional marine biodiversity and recovering fish populations to enhance food security. [ABSTRACT FROM AUTHOR]

Sea temperature increases may compromise ecological restoration as a tool for recovering degraded coral reefs. A potential solution may lay within using corals with naturally higher thermal resilience, such as intertidal corals. This study aimed at comparing thermal resilience, growth and survival between intertidal and subtidal corals in a reciprocal transplant experiment. Sixty coral nurseries were installed in a shallow coral reef area in Kenya: half were placed in the intertidal zone and half in the subtidal zone. At both zones, intertidal and subtidal Pocillopora cf. damicornis coral fragments were cultured in equal proportions, resulting in 15 replicate nurseries for four treatments. After an initial culture phase of 1 month in situ, six nurseries per treatment were thermally stressed ex situ by exposing corals for 5 days to a temperature of 32 °C (3 °C above summer maximum), after which they were returned in situ to recover. Fragment brightness was measured as the response variable to thermal stress. Intertidal and subtidal corals increased brightness (i.e., bleached) at a similar rate, but during recovery intertidal corals returned quicker to their original brightness in both culture environments. Coral growth was highest for intertidal corals in the intertidal zone during cooler months and was highest for subtidal corals in the subtidal zone during peak temperatures. Intertidal corals transplanted to the subtidal zone registered the lowest survival. Thus, intertidal corals display higher thermal resilience through quicker recovery, but potential trade-offs require further investigation before these corals can be used as a climate-proof broodstock for reef restoration. [ABSTRACT FROM AUTHOR]

The die‐off of the long‐spined sea urchin Diadema antillarum in the 1980s highlighted its crucial role as a primary grazer in tropical western Atlantic coral reefs. However, natural recovery has been slow, exacerbated by a new die‐off in 2022. Interest in actively restoring D. antillarum populations has grown with the emergence of culture and rearing techniques. Restocking reefs with laboratory‐reared urchins shows potential for enhancing coral reef resilience by reducing algal cover and promoting coral settlement, but success rates vary. Predation and migration contribute to low retention rates, with distinguishing between them is challenging. In this study near Saba, Caribbean Netherlands, we released 200 laboratory‐reared D. antillarum on a reef and monitored for D. antillarum retention and potential D. antillarum predator presence and interaction for 35 days. Only 40% of the urchins were still present on the reef after day one. The Spanish hogfish Bodianus rufus was identified as the primary daytime predator, responsible for nine direct predation events. No nighttime predation was observed, but interaction with a batwing coral crab Carpilius corallinus was noted. These insights can help optimize future restocking attempts and emphasize the importance of assessing predator presence beforehand. Reefs with high abundances of predators such as Spanish hogfish should be avoided for D antillarum restocking. In addition, before being released, lab‐reared animals should be given time to acclimate to conditions in the wild by being placed in protected in situ cages. Here, they could also grow to larger sizes that are less vulnerable to predation. [ABSTRACT FROM AUTHOR]

Coral reefs face threats from climate change and local pressures that lead to reductions in their physical structure, impacting biodiversity by limiting habitat availability. Despite many efforts to actively restore damaged reefs, few projects provide thorough evaluations of their success. This study measured the success of the "Reef Star" method at the Mars Coral Reef Restoration Project in Indonesia in reestablishing the physical structure of reef habitats that were destroyed by blast fishing. We used photogrammetry surveys to measure the physical habitat structure of 17 large sites (1000 m2 each), calculating three complementary measures of small‐ and large‐scale habitat complexity across degraded, restored, and naturally healthy coral reefs. We demonstrate that the restoration efforts have successfully restored small‐scale habitat complexity, as described by surface complexity metrics (3.22 ± 0.27 on restored reefs; 2.85 ± 0.26 on healthy reefs) and fractal dimension (2.27 ± 0.02 on restored reefs; 2.24 ± 0.02 on healthy reefs). This demonstrates the capacity for restored reefs to recover important ecosystem functions that are lost in degradation. However, while restoration has delivered some increases in large‐scale habitat complexity compared to degraded reefs, restored reefs still exhibit lower values of maximum vertical relief than healthy reefs, due to a lack of large physical structures. This lack of available large‐scale habitat might impact fish populations, meaning that restored reefs with limited large‐scale complexity may only support a restricted range of ecosystem functions. Effective reef restoration strategies must use a mixture of different methods that target the recovery of structural complexity at multiple scales. [ABSTRACT FROM AUTHOR]

Coral restoration plays a pivotal role in mitigating the decline of coral reefs, increasing the need for implementing effective techniques and methodologies. This study investigates the efficacy of stocking Acropora muricata and Pocillopora grandis using fishing line versus rope in mid‐water floating nurseries, offering valuable insights for coral restoration practitioners. Over 1 year, survival, tissue cover, growth, cleaning time, cost, preparation, and stocking timing for both methods were evaluated. Fishing line reduced contact with fouling organisms, contributing to enhanced coral tissue cover and growth rates for P. grandis compared to rope, but no significant effect was detected for A. muricata. Survival differed among species, with higher rates for P. grandis compared to A. muricata, indicating no impact due to stocking methods but species‐specific differences. Challenges like nursery collapses and amphipod outbreaks may have impacted survival, emphasizing the importance of consistent maintenance and accessibility of project sites. Furthermore, the fishing line method reduced cleaning effort. However, cost considerations and preparation complexities for fishing line warrant careful evaluation, particularly with regards to project budgets. The study underscores the necessity for further research, incorporating diverse genotypes, species, and initial fragment sizes to refine restoration strategies. In summary, this study provides important guidance for coral restoration practitioners, aiding informed decisions on stocking methods for different projects and species while considering the balance between coral health benefits and operational feasibility. [ABSTRACT FROM AUTHOR]

Stony coral tissue loss disease (SCTLD) has swept through Florida reefs and caused mass mortality of numerous coral species. In the wake of these losses, efforts are underway to propagate coral species impacted by SCTLD and promote population recovery. However, numerous knowledge gaps must be addressed to effectively grow, outplant, and restore populations of the slower growing, massive species that were lost. Here, we used sexual recruits of Diploria labyrinthiformis spawned in captivity to understand how conditioning, coral size, and nutritional status at outplanting affect coral survivorship, growth, and susceptibility to predation. We found that ex situ conditioning with supplemental feeding increased coral growth rates, resulting in larger sized corals at the time of outplanting. In turn, these corals had higher growth rates in the field and a lower probability of being removed by predators than outplants that were conditioned in in situ nurseries. Additionally, we found that coral size was an important predictor of survivorship, suggesting that hastening the speed at which young corals grow and outplanting larger juveniles can improve restoration outcomes. Taken together, our results suggest that providing supplemental food to corals at ex situ facilities confers benefits that could help restore populations of massive coral species impacted by SCTLD. [ABSTRACT FROM AUTHOR]

The article discusses the threats faced by coral reefs due to climate change, including bleaching and aggressive algal blooms. Scientists are working on ways to track and analyze reef health, as well as constructing artificial reefs to protect these ecosystems. Additionally, research shows that playing healthy reef sounds can encourage coral larvae to recolonize damaged reefs, offering hope for reef restoration efforts. French researchers have developed a non-invasive device to analyze dissolved compounds in seawater, providing insights into ecosystem health. [Extracted from the article]

The coral reefs along Pakistan's coastline are of ecological and economic significance. However, they are increasingly threatened by anthropogenic threats and climate change. These vulnerable ecosystems are declining due to various factors such as sedimentation, climate change, overfishing, destructive fishing practices, marine pollution, and tourism development. We found that 29%, 24%, 26%, 16% and 18% of the studies exceeding, marine pollution, overfishing/destructive fishing, coastal tourism, climate change and sedimentation, respectively; thus, indicating inadequate water quality status in part of Pakistan coastal water. These influences lead to several negative impacts, such as jeopardized coral health, decline in biodiversity, and the simplification of reef structures. In response to these threats, conservation efforts are imperative. This literature review provides an in-depth analysis of anthropogenic threats, climate change and the conservation of coral reefs in Pakistan. This review provides suggestions on how the country could better conserve its coral reef ecosystem. These include (1) initiatives such as establishing marine protected areas (MPAs), (2) encouraging sustainable fishing practices and reducing pollution, (3) developing the country as an ecotourism destination and implementing climate change adaptation measures, and (4) community engagement through awareness campaigns and fostering collaboration among, governmental organizations, non-governmental organizations (NGOs) and scientists. These comprehensive conservation policies address human-caused and other challenges, safeguarding their ecological, economic, and cultural relevance for future generations. [ABSTRACT FROM AUTHOR]

Implementation of coral restoration practices within reef management strategies is accelerating globally to support reef resilience and recovery. However, full costs underpinning restoration project feasibility have historically been underreported yet are critical to informing restoration cost-benefit decision-making. Such knowledge is especially lacking for Australia's Great Barrier Reef (GBR), where a coral restoration program led by reef tourism operators, Coral Nurture Program (CNP), was initiated in 2018 (northern GBR) and continues to scale. Here we describe the early outcomes and costs of implementing similar tourism-led asexual coral propagation and outplanting practices in a new region, the Whitsundays (central GBR) through the CNP. Specifically, we detail the local operational and environmental context of CNP Whitsundays, describe the costs of implementation and continuation of restoration activities, as well as evaluate survivorship of coral outplants across three restoration sites for nine months after project establishment (August 2022 to June 2023). Baseline benthic surveys revealed relatively low hard coral cover at restoration sites (ranging from 3.22-8.67%), which significantly differed in benthic composition from coral collection sites (ranging 16.67-38.06%), supporting strong motivation by tourism operators to undertake restoration activities. Mean coral survivorship of coral outplants in fate-tracked plots differed between the three restoration sites after 267 days (ranging 23.33-47.58%), with declines largely driven by coral detachment. Early-stage cost-effectiveness (costs relative to outplant survival) associated with implementation of restoration activity varied widely from US$33.04-178.55 per surviving coral (n = 4,425 outplants) depending on whether 'in-kind' costs, restoration activity (outplanting only vs. total costs encompassing planning through to monitoring), site-based survivorship, or a combination of these factors, were considered. As coral reef restoration projects continue to be established globally, our results highlight the need for ongoing, long-term monitoring that can inform adaptive practice, and fully transparent costreporting to understand and improve feasibility for any given project. We further highlight the inherent context-dependency of restoration costs, and the importance of considering local social-environmental contexts and their associated cost-benefits in economic rationale for reef restoration projects. [ABSTRACT FROM AUTHOR]

Out‐planting corals onto coral reefs as a mechanism to increase coral cover on degraded reef systems is an increasing global activity. Current practices typically focus on asexual out‐planting of coral fragments (coral gardening). Newer sexual reproductive approaches are being developed to out‐plant younger corals produced in aquaculture facilities or sea‐based rearing pools to enable assisted evolution or assisted gene flow conservation genetics approaches. Designing out‐planting deployment operations requires decisions to be made on planting density and location in order to maximize future recruitment on both the out‐planted reefs, and on nearby reefs that are connected through oceanographic transport processes. The thinking presented here seeks to unpack how out‐planting density may be influenced, especially by local oceanographic conditions, in order to guide practitioners undertaking restoration projects. [ABSTRACT FROM AUTHOR]

Promoting resilience is highly relevant to preserving biodiversity and ecosystem functioning. For coral reefs, parrotfish protection emerged as a mainstream action for reversing the degradation experienced by these systems. The rationale is that restoring their populations will increase grazing activity and reinforce control of fast‐growing macroalgae, facilitating coral cover recovery. A lack of a link between parrotfish trends and macroalgae and coral cover trends at a large scale has, however, often been the case. Suggesting more complex underlying dynamics that should be reexamined. In this review, we discuss how lumping parrotfish species as if they were functionally redundant may obscure trends. And how a lack of appreciation of other functions around the parrotfish paradigm, specifically bioerosion, may have unforeseen and potentially adverse effects on degraded reefs. We show that bioerosion responded more directly and quickly to spatial and temporal changes in parrotfish assemblages than macroalgae consumption, arguably due to the varying vulnerability among Caribbean parrotfishes to fisheries and habitat loss. For highly degraded reefs, positive changes in parrotfish populations could hence compromise the remaining coral skeleton structures and the reef framework, further accentuating reef degradation, where increases in macroalgae consumption could not necessarily compensate for higher rates of bioerosion. [ABSTRACT FROM AUTHOR]

ABSTRACT The current rapid climate warming is expected to cause an ocean temperature increase of 3°C–5°C by 2100, leading to deoxygenated and acidified tropical seas. Without mitigation measures, the total loss of tropical corals is inevitable. Already, one‐third of tropical reefs are considered permanently lost. Coral bleaching initiated by the loss of symbionts, the photosynthetic zooxanthellae, is the main process whereby corals respond to thermal stress, followed by recovery. However, increased thermal stress and frequency of bleaching have caused widespread coral recovery failure. Zooxantheallae of the genus Symbiodinium are considered the thermally vulnerable part of the coral symbiosis. In recent decades, warming has displaced genotypes of lower thermal resilience to subtropical latitudes; few genotypes of higher temperature tolerance remain abundant in tropical seas, but these will not withstand warming predictions either. Interestingly, high temperatures in the Red Sea have selected for exceptionally heat‐resistant coral genotypes and for the highest known thermal resilience in endemic zooxanthellae at the same time. Actions to overcome the coral bleaching crisis have been proposed by combining coral ecophysiology and mass culturing of thermally resilient Red Sea symbionts for naturalisation to the global tropical ocean, including restoration of collapsed reefs using corals with thermally resilient symbiont genotypes. [ABSTRACT FROM AUTHOR]

Anthropogenic pressure is increasing the variety and frequency of environmental disturbance events, limiting recovery and leading to long‐term declines in wild plant and animal populations. Coral reefs and associated fish assemblages are inherently dynamic due to their susceptibility to a host of disturbances, but regional‐scale nuances in the drivers of long‐term change frequently remain poorly resolved. Here, we examine the effects of multiple potential drivers of change in coral reef fish assemblages across 4 inshore regions of the Great Barrier Reef Marine Park (GBRMP), Australia, over 12–14 years (2007–2021). Each region had a unique disturbance history, in conjunction with long‐term changes in physical and habitat variables. Phases of recovery were apparent in the years between disturbance events at all locations, but these were not long enough to prevent substantial declines in reef fish density (by 33%–72%) and species richness (by 41%–75%) throughout the study period. The main drivers of change in fish assemblages varied among regions; however, the most rapid changes followed cyclone and flood events. Limited recovery periods resulted in temporal shifts in fish species composition from typically coral‐associated to algae‐associated. Most trophic groups declined in density except farmers, grazers, omnivores and parrotfish. No‐take marine reserves (NTMRs) had small and inconsistent effects on total fish assemblages, but delivered benefits for fishery‐targeted piscivores. Our findings suggest that coral reef responses to local stressors and cumulative escalating climate change impacts are highly variable at regional scales, and that small NTMRs are unlikely to mitigate the impacts of increasingly frequent climatic disturbances. Nearshore coral reefs worldwide are high‐value habitats that are either already degraded or vulnerable to degradation and the loss of important fish groups. Global efforts to reduce greenhouse gas emissions must be coupled with effective local management that can support the functioning and adaptive capacity of coral reefs. [ABSTRACT FROM AUTHOR]

In the face of escalating threats posed by human-induced climate change, urgent attention to coral reef restoration is imperative due to ongoing reef degradation. Here, we explored the potential of generating coral micropropagates as a tool to rapidly generate coral tissue for reef restoration and reef engineering. We developed a hypersalinity-induced polyp bailout protocol and a simple attachment device to support the growth of micropropagates on commonly used restoration substrates. We found that hypersalinity induction, at a rate of < 1 ppt hr-1, produced healthy micropropagates of the coral Stylophora pistillata. The highest attachment success (-74%) was achieved in CaCO3 substrate devices, which outperformed PVC (-48%) and Portland cement (-5%). Settled micropropagates displayed rapid growth rates on both CaCO3 (0.037 mm²/day ± 0.002 SE) and PVC (0.057 mm²/ day ± 0.008 SE) substrates, while Portland cement induced tissue degradation. Our study provides a detailed methodology for reliably generating, attaching, and growing coral micropropagates and underscores the potential of polyp bailout as a viable technique supporting coral propagation efforts. [ABSTRACT FROM AUTHOR]

The capacity for natural coral reef recovery and the effectiveness of active restoration efforts are often contingent upon uncertain and understudied background variables, such as chronic predation for example. In the Maldives, small coral colonies (< 10 cm), primarily from the genera Pocillopora and Acropora (often found recolonising degraded reefs) are frequently predated on by the spiny cushion sea-star (Culcita schmideliana). Incidentally, these same corals (especially Acroporids) are often prioritised in active reef restoration practices. However, the level of risk these corallivores pose on restoration success has not yet been assessed. Here, we aimed to initially document the population densities of C. schmideliana on a degraded reef system in the Maldives (Kunfunadhoo, Baa Atoll). We then assessed their associated predatory effects on coral recruits and transplants, and explored the benefits of C. schmideliana removal on the survival of these corals. Population densities ranged between 1.2 and 3.3 individuals per 100 m2, which resulted in high predation rates on coral recruits (4 – 20%) and transplants (11 – 43%). Culcita schmideliana predation accounted for the majority of the documented mortality (85%). Where C. schmideliana were removed, a significant increase in survival for recruits (9% higher) and transplants (24% higher) was shown. Further observations linked a cessation of C. schmideliana removal to a significant rise in predation instances for previously protected corals (up to 52%). Our study therefore highlights the severe impacts of C. schmideliana predation and shows Culcita spp. population management as a viable passive solution for effective reef restoration. [ABSTRACT FROM AUTHOR]

Periodic outbreaks of crown‐of‐thorns starfish have led to severe coral reef degradation, with one hypothesized cause being eutrophication. Phosphorus (P) is one of the driving factors for eutrophication, but researches on the spatiotemporal distributions of P in coral reefs are limited, impeding our understanding of the P cycling in coral reefs and its correlation with starfish outbreaks. This study undertook an analysis of various P species, migration and transformation in seawater, sediments, and crown‐of‐thorns starfish within the coral reefs of the Xisha Islands, northern South China Sea. The results show that in seawater, P predominantly existed in the dissolved phase, with organic P constituting the largest fraction (>67%). Conversely, in sediments, P primarily existed as inorganic form (43%−95%), with calcium‐bound P comprising the majority (26%−46%). Notably, exchangeable P accounted for a relatively smaller fraction (9%−20%) but played a significant role as a source of P released from sediments into seawater (0.01−0.17 mmol m−2 hr−1). During starfish outbreaks, starfish (1,000 individuals per hectare) assimilated P from seawater via phytoplankton or corals, resulting in substantial accumulation of both organic and inorganic P in their tissues (69−315 μmol g−1). Meanwhile, starfish excretion released P back into the seawater, which contributes to the migration and transformation of various P forms. Historical data also show a close relationship between P content and starfish density. These findings highlight the interactions between starfish and P cycling within coral reefs, and provide valuable insights into conservation and restoration on coral reefs, especially those severely affected by starfish outbreaks. Plain Language Summary: The coral reefs of the Xisha Islands, northern South China Sea have experienced periodic outbreaks of crown‐of‐thorns starfish, causing severe degradation of the coral reefs. However, the reasons for the outbreak of starfish remain unclear. This study aims to investigate the relationship between P content and starfish outbreaks, and examines where and how P migrates and transforms in seawater, sediments, and crown‐of‐thorns starfish. This study discovered that the majority of P in seawater existed in a dissolved state, primarily as organic compounds. In sediments, P existed mostly in inorganic forms, particularly bound to calcium, which is commonly found in coral reef sediments. The proportion of exchangeable P which can easily migrate from the sediments into the seawater was the least. During starfish outbreaks in the Xisha Islands, the density of starfish can hit 1,000 individuals per hectare. These starfish assimilated P from seawater via phytoplankton or corals, resulting in significant amounts of both organic and inorganic P within their tissues. Yet, starfish excretion releases P back into the seawater. This study linked starfish outbreaks to DIP levels, which helps us understand the P cycling in coral reefs and provides some outlooks on coral reef conservation in the context of starfish outbreaks. Key Points: Water P in Xisha's coral reefs mainly existed in DOP, as a significant DIP source via degradationPorous calcium carbonate boosted Ca‐P and Ex‐P proportion and DIP release in reef sedimentsCrown‐of‐thorns starfish stored and released OP and IP, affecting P cycle and starfish outbreaks [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]

This editorial titled "Restoration of coastal marine ecosystems" discusses the importance of ecosystem restoration in coastal marine habitats and the goals set by the United Nations to protect and restore degraded ecosystems. It highlights the challenges and uncertainties associated with large-scale restoration efforts in marine ecosystems and presents new insights and achievements in marine ecosystem restoration. The document covers various topics and ecosystems, including seagrass beds, macroalgal forests, estuarine wetlands, oyster reefs, and coral reefs, and provides successful restoration case studies. The article emphasizes the importance of stakeholder involvement, long-term monitoring, and measures to improve the resilience of restored ecosystems in the face of climate change. It concludes by calling for intensified and scaled-up restoration efforts, supported by government actions and partnerships with commercial and industrial sectors. [Extracted from the article]

Interpreting and responding to environmental cues from different modalities has survival value. In fish, the role of multimodal perception has been studied in regard to both foraging and risk assessment, with modalities including vision, olfaction, and mechanoreception via lateral lines. We studied reef fish boldness by placing novel objects that obstructed vision, lateral line use, or both into a coral reef environment with native algal samples inside, and then quantifying exploration as a function of obstruction type and as a function of functional diet groups (herbivores, omnivores, carnivores). Fish were more neophobic with more sensory obstructions, displaying longer latencies to visitation across all novel objects. Fish were also less likely to pass by objects that blocked multiple perceptual modalities. Across diets, there is early evidence that different functional groups respond differently to novelty. However, this conclusion requires further study. Overall, our findings provide key insights into perceptual ecology. In turn, this knowledge can be applied to understanding the effects of novel anthropogenic modifications in the marine environment. Such modifications may include positive activities like the construction of substrates to restore coral reefs, coral transplantation to restore reefs, as well as the negative consequences of construction and pollution. [ABSTRACT FROM AUTHOR]

The decline of coral reefs has increased interest in ecological restoration. Due to the scarcity of coral gardening projects in the Eastern Tropical Pacific, improving our understanding of such techniques is key. We report the results of coral gardening using the branching Pocillopora spp. and massive coral species (Pavona gigantea, Pavona clavus and Porites lobata) in an upwelling area in Costa Rica. We examined whether nursery type influenced Pocillopora spp. survival and growth, and how environmental conditions shaped restoration. We monitored the survival and growth of Pocillopora spp. fragments (n = 334) and microfragments of massive species (P. gigantea [n = 148], P. clavus [n = 37], P. lobata [n = 66]) over 11 months. Survival at the end of the gardening period was 51% for Pocillopora spp., 59% for P. clavus, 55% for P. gigantea, and 17% for P. lobata, with a decline after a cease in maintenance caused by the COVID-19 lockdown. Pocillopora spp. fragments in the floating nurseries exhibited higher growth (7.52 ± 1.98 and 6.64 ± 2.91 cm yr-1) than in the A-frame (4.16 ± 2.35 cm yr-1), which suggests the benefits of suspending fragments. For massive microfragments coral growth was 1.92-4.66 cm² yr-1 and were affected by pigmentation loss, causing partial tissue loss and mortality. Our results point towards acclimation to local conditions, and show the need to develop site-specific cost-efficient gardening techniques for massive species, allowing for a multi-species approach to ensure long-term ecosystem recovery. [ABSTRACT FROM AUTHOR]

Background: Coral reefs experience frequent and severe disturbances that can overwhelm their natural resilience. In such cases, ecological restoration is essential for coral reef recovery. Sexual reproduction has been reported to present the simplest and most cost-effective means for coral reef restoration. However, larval settlement and post-settlement survival represent bottlenecks for coral recruitment in sexual reproduction. While bacteria play a significant role in triggering coral metamorphosis and settlement in many coral species, the underlying molecular mechanisms remain largely unknown. In this study, we employed a transcriptome-level analysis to elucidate the intricate interactions between bacteria and coral larvae that are crucial for the settlement process. Results: High Metabacillus indicus strain cB07 inoculation densities resulted in the successful induction of metamorphosis and settlement of coral Pocillopora damicoris larvae. Compared with controls, inoculated coral larvae exhibited a pronounced increase in the abundance of strain cB07 during metamorphosis and settlement, followed by a significant decrease in total lipid contents during the settled stage. The differentially expressed genes (DEGs) during metamorphosis were significantly enriched in amino acid, protein, fatty acid, and glucose related metabolic pathways. In settled coral larvae induced by strain cB07, there was a significant enrichment of DEGs with essential roles in the establishment of a symbiotic relationship between coral larvae and their symbiotic partners. The photosynthetic efficiency of strain cB07 induced primary polyp holobionts was improved compared to those of the negative controls. In addition, coral primary polyps induced by strain cB07 showed significant improvements in energy storage and survival. Conclusions: Our findings revealed that strain cB07 can promote coral larval settlement and enhance post-settlement survival and fitness. Manipulating coral sexual reproduction with strain cB07 can overcome the current recruitment bottleneck. This innovative approach holds promise for future coral reef restoration efforts. [ABSTRACT FROM AUTHOR]

Coral reefs, vital ecosystems supporting diverse marine life, are primarily shaped by the clonal expansion of coral colonies. Although the principles of coral clonal growth, involving polyp division for spatial extension, are well-understood, numerical modelling efforts are notably scarce in the literature. In this article, we present a parsimonious numerical model based on the cloning of polyps, using five key parameters to simulate a range of coral shapes. The model is agent-based, where each polyp represents an individual. The colony's surface expansion is dictated by the growth mode parameter (s), guiding the preferred growth direction. Varying s facilitates the emulation of diverse coral shapes, including massive, branching, cauliflower, columnar and tabular colonies. Additionally, we introduce a novel approach for self-regulatory branching, inspired by the intricate mesh-like canal system and internode regularity observed in Acropora species. Through a comprehensive sensitivity analysis, we demonstrate the robustness of our model, paving the way for future applications that incorporate environmental factors, such as light and water flow. Coral colonies are known for their high plasticity, and understanding how individual polyps interact with each other and their surroundings to create the reef structure has been a longstanding question in the field. This model offers a powerful framework for studying these interactions, enabling a future implementation of environmental factors and the possibility of identifying the key mechanisms influencing coral colonies' morphogenesis. [ABSTRACT FROM AUTHOR]

Microhabitat associated fishes are expected to be negatively affected by coral reef degradation, given that many species are coral dwellers. However, the factors underlying this negative impact and the spatial scale(s) at which it occurs are poorly understood. We explored how habitat quality metrics and host preferences influence fish abundance across multiple spatial scales, using the functionally important cleaner fish Elacatinus evelynae as a study species. We surveyed fish at 10 sites in Curaçao that varied in coral cover and health. At the microhabitat scale, we found that E. evelynae group size increases on large, healthy corals and on some coral host species, namely Montastraea cavernosa. We also found that, although E. evelynae can occupy at least 10 coral host species, it selectively inhabits just three corals: M. cavernosa, Colpophyllia natans, and Diploria labrynthiformis. Scaling up to explore goby abundance along 30‐m transects, we did not find a clear relationship between live coral cover and goby abundance. However, goby abundance was substantially higher at one location with elevated coral cover and a high relative abundance of E. evelynae host species. Collectively, these results confirm that E. evelynae abundance is impacted by reef health. They also indicate that the species' long‐term persistence may depend on both the maintenance of healthy coral hosts and the gobies' plasticity in host preferences on changing reefscapes. Cryptobenthic fishes such as E. evelynae play a vital role in the ecosystem and understanding drivers of their abundance is important as reefs face increased degradation. [ABSTRACT FROM AUTHOR]

Ecosystem responses to disturbance depend on the nature of the perturbation and the ecological legacies left behind, making it critical to understand how climate‐driven changes in disturbance regimes modify resilience properties of ecosystems. For coral reefs, recent increases in severe marine heat waves now co‐occur with powerful storms, the historic agent of disturbance. While storms kill coral and remove their skeletons, heat waves bleach and kill corals but leave their skeletons intact. Here, we explored how the material legacy of dead coral skeletons modifies two key ecological processes that underpin coral reef resilience: the ability of herbivores to control macroalgae (spatial competitors of corals), and the replenishment of new coral colonies. Our findings, grounded by a major bleaching event at our long‐term study locale, revealed that the presence of structurally complex dead skeletons reduced grazing on turf algae by ~80%. For macroalgae, browsing was reduced by >40% on less preferred (unpalatable) taxa, but only by ~10% on more preferred taxa. This enabled unpalatable macroalgae to reach ~45% cover in 2 years. By contrast, herbivores prevented macroalgae from becoming established on adjacent reefs that lacked skeletons. Manipulation of unpalatable macroalgae revealed that the cover reached after 1 year (~20%) reduced recruitment of corals by 50%. The effect of skeletons on juvenile coral growth was contingent on the timing of settlement relative to the disturbance. If corals settled directly after bleaching (before macroalgae colonized), dead skeletons enhanced colony growth by 34%, but this benefit was lost if corals colonized dead skeletons a year after the disturbance once macroalgae had proliferated. These findings underscore how a material legacy from a changing disturbance regime can alter ecosystem resilience properties by disrupting key trophic and competitive interactions that shape post‐disturbance community dynamics. [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]

Coastal and marine ecosystems provide valuable ecosystem services and functions. Unfortunately, these habitats have experienced increasing anthropogenic and climate‐related pressures, leading to significant degradation and loss not only in Australia but also globally. Hence, the urgency for coastal and marine ecosystem restoration has never been more pronounced. We present a synthesis of 151 projects on coastal and marine restoration in Australia spanning mangrove, seagrass, tidal marsh, kelp, shellfish reef, and coral ecosystems. Our findings reveal increased restoration efforts over the past 30 years, with an increased focus on coral and shellfish reef habitats. Across Australia, most efforts were in southeastern Australia, with a noticeable gap in the Northern Territory. Restoration strategies focused on enhancing propagule availability (74%) and substrate availability (42%), with additional efforts toward implementing top–down (7%) and bottom–up (4%) controls to boost natural recruitment. Projects were carried out with the participation mostly of research universities (45%), followed by state government entities (42%), philanthropy (34%), and private companies (16%). Funding came primarily from governmental sources, such as state government entities (50%), the commonwealth (44%), and philanthropy (19%). Restoration outcomes are centered on monitoring growth and survival resulting from both single and multiple restoration actions. Our findings highlight key factors influencing natural recruitment across habitat types, where sedimentation and species reproductive biology play a critical role. While acknowledging that our results represent only a small fraction of Australia's coastal and marine restoration efforts, our intent is to contribute insights that can support large‐scale restoration actions not only in Australia but also on a global scale. [ABSTRACT FROM AUTHOR]

Mass culturing coral larvae collected from spawn slicks during spawning events and rearing them directly on reefs is an important method for coral reef restoration as it utilizes high genetic diversity and is readily upscaled. Understanding optimal initial stocking densities in mass cultures is, therefore, central to optimizing larval production efficiency. Yet, no studies have focused on optimizing initial stocking densities while coral embryos are still floating, despite the influence of density‐dependent effects during larval culturing. This study aimed to (1) explore initial stocking densities based on slick coverage and (2) determine the effects of initial densities on embryo development to coral settlement and early post‐settlement survival. Wild coral spawn slicks were collected at Lizard Island and reared at different combinations of slick coverage and density based on tank volume. Immediate density‐dependent effects were observed in treatments with 45% slick coverage, which had lower abundances of embryos 12 hours post‐spawning. The 12‐hour embryo densities ranged from 1.7 to 10.7 mL−1 and continued to display a negative relationship between density and survival of developing larvae. Overall, a density of approximately 5.1 embryos mL‐1 was the optimal stocking density for larval survival to competency (16.5%). The proportion of settlement and early post‐settlement survival was negatively correlated with higher initial densities, while a positive relationship was observed between the abundance of competent larvae and those settled, including initial settlers and 2‐month‐old recruits. These results highlight the importance of both larval quality and supply, and opportunities for site and system‐specific optimization of larval production in future work. [ABSTRACT FROM AUTHOR]

Reef restoration has gained attention as it has strategic actions and powerful means in sustaining and maintaining coastal ecosystem services. This scientometric study systematically analyzes the current trends and research hotspot in coral restoration across the last five decades (1971–2022). The metadata (12,667 articles with 652,860 cited references) were obtained from the Clarivate Web of Science platform through the Core Collection database, associated with the CiteSpace and R‐software for further analysis. The results indicated that the trend of coral restoration is increasing in paper/year, with the United States, Australia, and China as major contributors to the related research. Furthermore, James Cook University, Australia had the largest number of articles, and the Consortium of Research Libraries of the United Kingdom was the most influential institution on coral restoration. The highly cited keywords are "Great Barrier Reef," "climate change," and "coral reef," while the most influential keywords are "coral," "model," and "Atlantic." A total of 23 clusters in the field with "coral reef," "phase shift," "bacterial communities," "coral restoration," "symbiotic dinoflagellate," "stony coral tissue loss disease," "bleaching event," "ocean acidification," "oyster reef," and "quantitative reconstruction" are among the top cluster size labeled. Early‐stage researcher may use both keywords and cluster analysis to find topics attractive to their future research projects. In addition, this study contributes toward evaluating recent scientific productivity about coral restoration as well as informing researchers and policymakers regarding funding, future strategic planning, and potential collaboration opportunities. [ABSTRACT FROM AUTHOR]

Determining the efficacy of restoration practices is critical for enhancing and rebuilding degraded ecosystems. A fundamental question in marine restoration design is whether to employ active (e.g. using living plants or oysters that form the biogenic habitat) or passive (e.g. restoring the hydrology and sediment materials at the site) restoration strategies. Furthermore, the identity of sources used in restoring biogenic habitats could influence the effectiveness of restoration efforts. We present results from two independent experimental restoration efforts designed to explore the efficacy of these different approaches for the recovery of Crassostrea virginica (eastern oyster) reef habitat. Conducted from 2015–2020 in Rhode Island, USA, the restoration experiments compared 1) passive (unseeded shell) vs. active (seeded spat on shell) restoration methods in Ninigret Pond, and 2) restored reefs seeded with hatchery sourced vs. wild oyster lineages in Quonochontaug Pond. In Quonochontaug Pond, the hatchery-sourced line exhibited greater mortality than the wild lines. Restored reefs in both projects remained viable all four years post-restoration; however, low recruitment continues to limit the long-term sustainability of restored reefs in these Rhode Island systems. Natural mortality varied spatially within each coastal pond, ranging from 33–81% per year. Across both experiments, oyster mortality increased with rising temperature, salinity, and disease prevalence. Our results suggest that utilizing active restoration with spat spawned from multiple sources, including wild populations, may improve the success of oyster restoration. Future habitat restoration efforts should consider the environmental variability associated with restoration sites and the source of restoration species during project planning. [ABSTRACT FROM AUTHOR]

Coral reefs are threatened by climate change and the effects of human activity on the marine environment. Researchers are attempting to rescue this fragile ecosystem through coral restoration actions, and a common step in these procedures is transplanting the new coral colonies into coral reefs. To do that, commercial concrete or epoxy resins, also called putty, are utilized, highlighting different concerns about their mechanical and hardening performances and their impact and fate once released into the environment. Hence, this study presents a new biodegradable epoxidized soybean oil acrylate (ESOA)/zein‐based coral putty capable of quick hardening underwater as an ecofriendly alternative for transplantation of new coral colonies in the reef. Coral putty is composed of two components, containing one a radical initiator and the other a radical accelerator. Once the two components are mixed, coral putty becomes hard underwater in 20–25 min, showing a hardening timescale much faster than other commercial products. The coral putty is biocompatible when applied to the coral Stylophora pistillata in aquaria and Acropora tenuis corals are out‐planted on the reef in the Maldives, demonstrating how this new class of vegetable‐oil‐based materials can be a more sustainable alternative to epoxy resins commonly used in coral restoration procedures. [ABSTRACT FROM AUTHOR]

Consumers can play critical roles in ecosystem resilience by modifying community resistance and recovery rates. In coral reefs, grazers can increase reef resilience by controlling algae and maintaining open space for coral recruitment, but can also erode the reef framework critical for coral recovery. Here we examine the context‐dependent effects of herbivores on reef persistence in Caribbean Panamá. Using a series of lab and field experiments, we found that the erosional effects of the herbivorous reef urchin (Echinometra viridis) were 2 orders of magnitude greater on dead corals than live corals, and surveys across multiple similarly overfished reefs revealed a positive relationship between urchin densities and percent cover of bare dead coral with urchin densities exceeding 150 m−2 in some reefs. However, we observed that a mat‐forming zoanthid (Zoanthus pulchellus), found exclusively on dead corals, had an inverse spatial relationship with urchins. Through a series of field experiments, we found that zoanthid overgrowth repelled urchins, increased dead coral persistence, and decreased erosion of dead corals making up the reef framework by more than 50% over a 22‐month period. Our findings reveal that zoanthids can provide associational refuge to dead corals by enhancing their persistence under high urchin grazing pressure. We suggest that secondary space‐holders, such as zoanthids, may play increasingly important functional roles in degraded reef systems by shielding coral skeletons from external bioeroders. Moreover, the Stress Gradient Hypothesis, which predicts that the importance of positive interactions such as associational refuges increases with consumer pressure, extends to dead foundation species such as coral skeletons crucial for ecosystem recovery. [ABSTRACT FROM AUTHOR]

Although position within the estuarine landscape is known to influence structural characteristics and ecological functioning of many habitats, the influence of position on subtidal oyster reef characteristics and functioning is relatively understudied. This study assessed habitat provision by oysters and benthic macrofauna on subtidal bar and patch oyster reefs within the northwestern Gulf of Mexico estuary. Bar reefs had greater and more variable oyster density, biomass, and volume, as well as dead shell material, compared to patch reefs. Benthic macrofaunal community composition differed between reef types, with bar reefs hosting 11× and 30× higher biomass of Porcellanidae and Ampithoidae crustaceans, and patch reefs supporting 34× and 47× higher biomass of Eunicidae annelids and Leptocheliidae crustaceans. The environmental variables most highly correlated with macrofaunal communities on both bar and patch reefs were sediment chlorophyll-a, volume of dead oyster shells, and depth. Despite differences in structural characteristics and position within the estuarine landscape, subtidal oyster reefs are often managed as a single habitat type. Our findings emphasize the importance of considering location in oyster reef conservation and restoration efforts to better predict and optimize faunal provision outcomes. [ABSTRACT FROM AUTHOR]

The Xisha Islands constitute the largest coral reef archipelago on the northern margin of the Coral Triangle and are the largest coral reef archipelago among the islands in the South China Sea. This study employed various survey methods including underwater spearfishing, gill netting, handline fishing, longlining fishing, underwater visual surveys, and environmental DNA (eDNA). Additionally, historical data from 1956 to 2023 were reviewed to comprehensively analyze the adaptation characteristics of the fish community structure in the Xisha Islands. The Xisha Islands have documented a total of 874 coral reef fish species, categorized into 27 orders, 102 families, and 337 genera. Of these species, the order Perciformes demonstrated the greatest species richness, which represents 71.05% of the total fish species documented. The structure of coral reef fish communities in the Xisha Islands has undergone significant changes. Firstly, a significant decline in the population of large-sized and carnivorous fish species was observed. The proportion of large-sized fish species diminished by 6.02% (62 species), and the medium-sized fish species saw a reduction of 3.09% (51 species). In contrast, there was a surge of 9.12% in the small-sized fish species population. The carnivorous fish species experienced a decrease of 4.73% (102 species), while an increase was noted in the population of herbivorous and omnivorous fish species. Secondly, the numbers of orders, families, and genera have also significantly decreased, with noticeable declines in the average taxonomic distinctness (Delta +), the variation taxonomic distinctness (Lambda +), functional richness (FRic), and quadratic entropy (RaoQ). Thirdly, the similarity between fish species at different time periods is relatively low. Among different functional groups, large-sized and carnivorous fish species exhibit the lowest similarity, whereas herbivorous fish species exhibit the highest. The turnover of live coral fish species is also evident. Overall, the coral reef fish in the Xisha Islands are showing a trend towards herbivory, miniaturization, and a simplification in species composition and functionality. This study contributes to a better understanding and prediction of the adaptation trends in fish species composition in the Xisha Islands, which is crucial for ensuring the ecosystem services of coral reefs and for the conservation and restoration of ecosystems. [ABSTRACT FROM AUTHOR]

Rapid acute heat stress assays are increasingly used to assess reef coral heat tolerance and identify resilient corals for research and restoration. However, concerns remain about (1) how representative they are of natural bleaching events, and (2) how reproducible they are in resolving differences in heat tolerance among corals. To address these gaps, we (1) compared rapid assays with an 8-day 'classic' bleaching experiment on Acropora pulchra genets (n = 20), and (2) tested and retested rapid assay responses of Acropora cervicornis (n = 85 genets) up to a year apart. In both species, rapid assays revealed a ~ 2.5 °C range in heat tolerance thresholds (Fv/Fm ED50s) among genets, and these thresholds were strongly predictive of individual bleaching responses in the classic bleaching experiment (R = 0.74). Retesting genets with rapid assays showed ED50 differences < 0.99 °C in 90% of cases (median = 0.47 °C), and controlling for environmental effects reduced these to < 0.54 °C (median = 0.23 °C). Even so, large differences (> 0.93 °C) were needed between two individual genets to reliably retest in the same rank order, though smaller margins were reproducible for groups (e.g., 0.29 °C for groups of 10). These results demonstrate that rapid assays may not resolve fine-scale individual heat tolerance differences, but they can easily identify top- and bottom-performing individuals, and differential tolerance between groups of corals. These findings provide critical validation and quantitative guidelines for the use of rapid assays, which may transform coral heat tolerance research and its applications to reef restoration. [ABSTRACT FROM AUTHOR]

Drastic declines observed in coral reefs in response to changes in climate and other anthropogenic stressors have hinged the survival of these ecosystems largely on the overall health and reproductive success of stony corals. One specific threat, Karenia brevis blooms, has drawn increased public attention in recent decades and has been documented to reach the Florida Keys, a vulnerable coral ecosystem. The purpose of this study was to investigate the sublethal impact of K. brevis exposure on three South Florida "restoration" coral species. Fragments of Porites astreoides, Acropora cervicornis, and Siderastrea radians were exposed to three environmentally relevant concentrations of K. brevis for 2 weeks in a controlled aquaria setting. At the end of exposure, ultra-high-performance liquid chromatography coupled to high-resolution tandem mass spectrometry (UHPLC-HRMS/MS) was used to perform nontargeted lipidomics and metabolomics analyses to assess physiological changes in the corals in response to red tide exposure, as well as highlight possible biological processes and pathways altered. Significant changes to the lipidome and metabolome were observed in all three species following exposure. Furthermore, the multi-omics analysis highlighted important pathways for further study including impacts on oxidative stress, energy metabolism, the immune system, and nitrogen fixation/photosynthesis of symbionts. Due to the use of environmentally relevant exposure levels and duration, these results are invaluable to understand possible future impacts of red tide on coral reef areas as well as to inform future coral reef restoration and management decisions. [ABSTRACT FROM AUTHOR]

Most comparative studies assessing reef health focus on living hard coral cover as the key metric. In Indonesia, in situ monitoring of coral cover has been ongoing for over five decades. However, as monitoring data and research findings are predominantly published in the local language (Bahasa Indonesia), local data often escape global attention, resulting in Indonesian coral reefs receiving less scientific attention despite accounting for ~ 15% of all coral reef area globally. Here, we systematically compiled both globally and locally published data on coral cover across Indonesia to assess changes over recent decades. We analysed 7,614 data entries extracted from 621 publications and found that the majority (79.1%) of the publications were written in Bahasa Indonesia, constituting 63.4% of the total data entries. Our dataset revealed limited evidence of net declines in coral cover over the last three decades (1994–2022). There was also no clear relationship between coral cover and human density, as well as with the thirteen environmental/anthropogenic drivers examined. We discuss several factors that may contribute to this lack of detectable large-scale change including: recent data potentially representing a 'shifted baseline'; the 'averaging out' of localised changes in coral cover dynamics at a broad scale; sampling biases; and/or the potential resilience of Indonesian coral reefs compared to other regions. This study highlights the wealth of accessible local coral reef data published in languages other than English and emphasises the importance of using such data to enhance our understanding of the long-term dynamics of coral reef ecosystems worldwide. [ABSTRACT FROM AUTHOR]

Introduction: Cold-water coral reefs form complex benthic habitats, supporting thousands of species. The broadscale environmental tolerances of reef-forming species such as Lophelia pertusa are well studied, but small-scale differences between different reef settings have received little attention so far. The controlling factors of thriving cold-water coral reefs and how these habitats differ in terms of framework extent, coral colony morphology, and associated fauna could reveal how these benthic ecosystems formand expand. Information on the natural range of environmental fluctuations could provide a better understanding of the resilience of such ecosystems towards environmental changes. Our study aimed to elaborate small-scale forces on local hydrodynamics and oceanographic parameters at two geographically close but contrasting reef sites in mid-Norway. Methods: We investigated natural fluctuations and the seasonal variability of environmental conditions of an inshore and an offshore Lophelia-dominated reef over an annual cycle by time series monitoring of physical properties by benthic landers and water sampling for biogeochemical variables using CTD casts. Results and discussion: The flow fields at the extensive reef on the offshore Sula Ridge and a bank reef at Nord-Leksa in a fjord-system differed regarding both short-term and seasonal levels. The inshore flow field was strong and tidally driven, whereas the offshore flow field was slower with large seasonal variability. The local flow regimes and the seasonal atmospheric forcing could explain the observed seasonality of the hydrographic variables and the observed inter-annual variability in biogeochemical variables. Comparison with a flow model showed that the natural short-term and seasonal variability are driven by small-scale forcing that is not represented in model analyses. These results suggest that local hydrodynamics together with sea-floor topography control the reef extent and the morphology of cold-water coral colonies. [ABSTRACT FROM AUTHOR]

Coral reef degradation is a worldwide and growing phenomenon triggering habitat transformation from live to dead coral fragments. Macroinvertebrates play key functions in coral reefs, yet research on the size distribution of their community attributes is limited, particularly in the Eastern Tropical Pacific (ETP). We assessed the size distribution of the macroinvertebrate communities in live and dead corals in an ETP coral reef off Colombia. Live coral supported greater macroinvertebrate biomass than dead corals. In live coral, > 90% of total biomass was allocated in the > 8 mm class, which was mostly represented by trapeziid crabs and alpheid shrimps, both obligate symbionts of Pocillopora colonies. No differences were found in macroinvertebrate densities between substrates. Macroinvertebrate communities were dominated by crustaceans, though not in every size class. In live coral, Decapoda dominated in all size classes except 0.5–1 mm, which was the only class where dominance of a single taxon was not observed. In dead corals, the dominance of crustaceans was only observed in the 0.5–1 mm class due to high abundances of tanaidaceans. The remaining size classes were dominated by Polychaeta (1–2 mm, 2–4 mm) and Ophiuroidea (4–8 mm, > 8 mm). Our findings highlight that coral degradation events could lead to macroinvertebrate assemblages with lower biomass contributions, higher proportions of small crustaceans (< 1 mm), and taxonomic shifts. Such transitions from live to dead corals could likely impact food-web interactions between macroinvertebrates and higher trophic levels, potentially altering the ecosystem services offered by coral reefs. [ABSTRACT FROM AUTHOR]

The growth properties and environmental adaptability of different corals and symbionts vary. Therefore, insights from the adaptive mechanisms of Symbiodiniaceae in corals are very meaningful. In this study, we surveyed the seawater characteristics at three sites on Luhuitou fringing reef, Hainan Island (China), sampling three native corals Pocillopora damicornis, Acropora hyacinthus, and Galaxea fascicularis on 27 September 2021. The photo-physiological (Fv/Fm, Y(II), α, and rETR) were measured, and high-throughput sequencing of Symbiodiniaceae ITS was performed. The Luhuitou site had the lowest temperature (28.845 °C ± 0.01), salinity (33.967 ± 0.03), and pH (8.468 ± 0.05) among the three sites. The Sanya site contained significantly the highest ammonium (7.406 μmol/L ± 1, P < 0.05). The nitrate of the Xiaozhou site was 1.5 times significantly higher than the other two sites. Three corals and their Symbiodiniaceae were adapted differently. P. damicornis showed more plasticity and was dominant by Cladocopium sp. C1d at high-ammonium habitat. A. hyacinthus was dominated by Cladocopium (C3 and C1232) and they had the lowest Fv/Fm (0.595 ± 0.02) in poor integrated water quality environments (the Xiaozhou site) among three corals, suggesting that the less adaptation. G. fascicularis established a stable symbiotic relationship with Durusidinium sp. D1, and they had a more stable symbiotic system and were better suited for long-term reef restoration. Our results provide a deeper understanding of the environmental adaptations of three corals at the Luhuitou fringing reef. Meanwhile, it provides a perspective application for coral transplantation species selection in restoring local reef ecology in the future. [ABSTRACT FROM AUTHOR]

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Coral reef ecosystems are facing severe degradation due to anthropogenic activities at both local and global scales. In response, extensive restoration efforts are underway, aiming to bolster coral cover and enhance reef fish communities to foster facilitation between fish and corals. This reciprocal relationship is anticipated to improve overall restoration efficacy and enhance coral reef resilience in the face of global warming. Here, we investigate the impact of coral restoration using out-planted Acropora cervicornis colonies attached to raised domes on the associated fish community on the isolated, well-protected reef of Little Cayman Island in the Central Caribbean. Surveys were conducted immediately preceding out-planting, five days later, and 85 days later to capture temporal changes in the fish community. After 85 days of out-planting, there were no changes in fish biomass, abundance, or species richness for the entire fish community. This pattern was consistent for selected fish functional groups. Additionally, no significant differences were observed in the fish community before outplanting, five days after out-planting, or 85 days after out-planting of restoration domes. Our results underscore the limited impact of coral restoration for influencing fish communities in the isolated and highly protected reef of Little Cayman over an 85-day period. Consequently, our findings have implications for using coral restoration as a mechanism to enhance fish populations, particularly in marginally disturbed regions where structural complexity has not been lost. Future restoration programs should therefore incorporate local knowledge of environmental history and restoration needs along with an increased data-driven understanding of the intricate interaction between fish and coral populations to be successful. [ABSTRACT FROM AUTHOR]

Sexual propagation of corals is a promising strategy for coral restoration, but one of the main challenges is the high mortality of coral spat due to competitive interactions with macroalgae during the early life history stages. Optimising the properties of settlement substrates such as material types and surface roughness has the potential to improve the survival of spat by limiting the recruitment and growth of macroalgae. In this study, we assessed the effects of modifying surface roughness across three different tile materials (alumina-based ceramic, calcium carbonate (CaCO3), and concrete) on the settlement success and post-settlement survivorship of Acropora kenti coral larvae in six mesocosm tanks, each with different established macroalgal communities. The macroalgal community compositions on the tiles were significantly different among material types, but not surface roughness, although the type and abundance of macroalgal species were heavily influenced by the established tank communities. Increasing surface roughness did not affect larval settlement success or spat survivorship. Substantially higher larval settlement density was found on concrete tiles (1.92 ± 0.10 larvae cm−2), but spat survival was the highest on CaCO3 tiles (73.4 ± 4.2% survived). Very strong competitive interactions were observed between spat and macroalgae, with overgrowth by the crustose coralline alga Crustaphytum sp. and the brown alga Lobophora sp. being the primary cause of spat mortality. Overall, when taking into account both settlement and survival rates, concrete was the best performing among the tile types tested here. [ABSTRACT FROM AUTHOR]

A key goal of coral restoration is to re-establish self-sustaining coral populations and ensure resilience to future stressors, which requires that genetic diversity is maximised. However, coral genetic and genotypic (clonal) diversity is variable across reef sites via success of sexual recruitment, and cryptic species diversity can complicate breeding efforts. Assessing genotypic and genetic diversity of colonies to be used in restoration is therefore critical to avoid founder, inbreeding or outbreeding effects. Considering recent efforts to upscale coral propagation on the Great Barrier Reef (GBR), we examined species, population and clonal structure of a commonly out-planted tabular Acropora species—Acropora hyacinthus (Dana, 1864). A total of 189 colonies were sampled from six reef systems throughout the northern-central GBR and genotyped using an Acropora-specific Affymetrix microarray, which resulted in 1387 variant sites that passed quality control. Cryptic species were readily resolved and all sampled A. hyacinthus colonies represented unique genotypes within sites at three reefs. At reefs that contained multi-ramet genets (clonal genotypes), the mean and maximum between-ramet distances were 0.68 and 1.99 m, respectively. Therefore, sampling colonies > 2 m apart increases the likelihood these colonies represent distinct genets. Such a sampling design therefore maximises genotypic diversity when sourcing colonies for propagation and out-planting. Based on these variant sites, we found no between-reef genetic divergence based on locality. Furthermore, through unintentional sampling of non-target tabular Acroporid species, we show how this genotyping method may be used for resolving taxonomic uncertainty as well as population dynamics. [ABSTRACT FROM AUTHOR]

Coral reef ecosystems host diversified and highly productive communities, but corals are degrading in many places worldwide. Picking suitable locations to maximize coral conservation and restoration efforts is critical. From a mass balance point of view, the supply of new nutrients is crucial to support a productive and reef-building coral ecosystem. Quantifying and qualifying available nutrients provide information to set region-specific thresholds for anthropogenic pollution monitoring and to generate research hypotheses. Here, we report the inorganic and organic nutrient levels from twenty-three sampling sites in coral reefs and coastal waters covering regions from high to low coral coverage, including two remote islands, Dongsha Atoll and Taiping Island, in the South China Sea. Some of the surveyed reefs received external inorganic nutrient supply via upwelling or submarine groundwater discharge (SGD), suggesting sites potential for new production (i.e., reef-building). Production or removal of organic matter at various sites is evidenced by their elevated or depleted organic carbon and nitrogen concentrations, respectively. The degree of impact by the upwelling and SGD on various inorganic and organic nutrient distribution varies. Among all sites, organic nitrogen accounts for most of the total nitrogen and is potentially a significant nitrogen source for the environment. The highly correlated total organic nitrogen (TON) concentrations and their C-to-N ratios (C/N-TON) suggest the production of TON with low C/N-TON and preferential removal of N during remineralization processes, leaving "leftover" TON with high C/N ratios. Furthermore, we found that high coral diversity and coverage sites are featured in low organic matter with high C/N, while macroalgae-dominating sites had elevated organic matter. The new data are valuable to generate hypotheses for future research to test, for example, whether sites with low organic matter are more suitable for restoring reef-building corals than sites with high organic matter. [ABSTRACT FROM AUTHOR]

Global warming can inhibit chlorophyll-based solar energy capturing of phytoplankton by decreasing nutrient supply through upwelling. However, species with proton-pump rhodopsin (PPR) can independently convert solar energy to cope with nutrient limitation. Besides prokaryotes, PPR has been documented in dinoflagellates and some species of other algal lineages, and its potential role in compensating for the deficiency of phosphorus has been demonstrated in dinoflagellates. However, PPR has not been studied in the coral reef endosymbiotic Symbiodiniaceae. Here, we report a PPR in Breviolum minutum (BmR). Both phylogenetic analysis and structure prediction results indicate that BmR resembles eukaryotic proton-pump rhodopsins, phylogenetically affiliated with the subgroup xanthorhodopsins. BmR contains the critical residues for proton pumping, retinal binding, and spectrum tuning for green absorption. To explore BmR's potential roles in responding to phosphorus limitation, we cultured B. minutum under different phosphorus conditions, and monitored physiological and BmR's transcriptional responses. Phosphorus limitation caused decreases in B. minutum population growth and photosynthesis efficiency. Meanwhile, our quantitative PCR showed that BmR expression was strongly upregulated under phosphorus limitation, showing a strong positive correlation with alkaline phosphatase activity and a negative correlation with photosynthetic efficiency. Our findings demonstrate that proton-pump rhodopsin occurs in Symbiodiniaceae and BmR has the potential to provide supplementary energy to support cell basal metabolisms when photosynthesis of B. minutum is impaired by phosphorus limitation, thereby enabling corals to better weather climate change. [ABSTRACT FROM AUTHOR]

The Fourth Global Coral Bleaching Event, confirmed by the National Oceanic and Atmospheric Administration (NOAA) and the International Coral Reef Initiative (ICRI), is a significant environmental challenge caused by climate change. The event began in the Caribbean in 2023 and has since spread to the Southern Hemisphere. The severity of the bleaching is driven by climate change, with El Niño events exacerbating the situation. The event has already caused devastating damage to coral reefs worldwide. To address this crisis, the International Coral Reef Society (ICRS) emphasizes the need for action in three key areas: mitigating greenhouse gas emissions, mitigating local stressors, and conducting active restoration efforts. Coral reef scientists play a crucial role in collecting standardized data, collaborating internationally, and protecting local reefs. Additionally, direct interventions such as coral restoration can provide hope for the future of coral reefs. However, urgent global efforts and funding are necessary to prevent further damage and ensure the survival of these ecosystems. [Extracted from the article]

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. [ABSTRACT FROM AUTHOR]