Search Results (149)

Artificial reefs are an important tool for marine ecological restoration and fishery resource proliferation, and are widely used around the world. Among them, Japan, the United States, China, South Korea, Australia, and the Mediterranean coastal countries have particularly invested in scientific research and practice in this field, and the reefs’ material selection, structural performance, and ecological benefits have attracted much attention. The purpose of this paper is to summarize the preparation methods, characterization methods (such as microstructure analysis and mechanical tests) and mechanical properties (such as compressive strength and durability) of new concrete materials (steel slag-blast furnace slag concrete, oyster shell concrete, sulfoaluminate cement concrete, recycled brick concrete, silica fume concrete, and banana peel filler concrete) that artificial reefs and ceramic artificial reefs developed in recent years, and to explore the resource utilization potential of different waste materials. At the same time, the biostatistical methods (such as species abundance and community diversity) of wood, shipwreck, steel, rock, waste tire, and ordinary concrete artificial reefs and their effects on the marine environment were compared and analyzed. In addition, the potential impact of artificial reef deployment on local fishermen’s income was also assessed. It is found that the use of steel slag, blast furnace slag, sulfoaluminate cement, and silica fume instead of traditional Portland cement can better improve the mechanical properties of concrete artificial reefs (compressive strength can be increased by up to 20%) and reduce the surface pH to neutral, which is more conducive to the adhesion and growth of marine organisms. The compressive strength of oyster shell concrete and banana peel filler concrete artificial reef is not as good as that of traditional Portland cement concrete artificial reef, but it still avoids the waste of a large amount of solid waste resources, provides necessary nutritional support for aquatic organisms, and also improves its chemical erosion resistance. The deployment of artificial reefs of timber, wrecks, steel, rock, waste tires, and ordinary concrete has significantly increased the species richness and biomass in the adjacent waters and effectively promoted the development of fisheries. Cases show that artificial reefs can significantly increase fishermen’s income (such as an increase of about EUR 13 in the value of a unit effort in a certain area), but the long-term benefits depend on effective supervision and community co-management mechanisms. This paper provides a scientific basis for the research and development of artificial reef materials and the optimization of ecological benefits, and promotes the sustainable development of marine ecological restoration technology and fishery economy. Full article

With the historical and consistent population declines of the eastern oyster (Crassostrea virginica), restoration projects commonly deploy plastic bags (polyethylene) filled with recycled oyster cultch. Oyster cultch bags are utilized as material to stabilize sediment and provide a substrate for oyster larval recruitment, which provides a habitat for associated organisms and decreases marsh erosion. In addition to the plastic mesh bags utilized to contain oyster cultch, this study also utilized three different biodegradable oyster bag material types (biopolymer, basalt, and cellulose) to determine (1) the influence of bag type on oyster population dynamics, (2) bag durability over time (<1 year), and (3) the cost–benefits for each bag type, calculated via a Weighted Product Model (WPM), within a subsection of the West Galveston Bay Estuary, Texas. For bag type, the results suggested that plastic bags were the most resilient, followed by biopolymer, basalt, and cellulose bags. Plastic bags supported the highest oyster abundance and growth, demonstrating their effectiveness for establishing breakwater reefs. The WPM analysis indicated that plastic bags are inexpensive to deploy and, due to their longevity, are easily monitored over time. However, degradation of plastic bags may introduce microplastics into the environment, posing ingestion risks for bivalves. Whereas the nature-based solutions degraded quickly, inhibiting continuous monitoring, yet the loose cultch may facilitate the natural formation of reefs over time. The results highlight tradeoffs between maximizing oyster recruitment and growth, minimizing environmental contamination, and balancing ecological performance with material sustainability in oyster reef restoration practices. Full article

Citizen science approaches for monitoring, and even restoring, coral reefs have grown in popularity though tend to be restricted to those who have taken courses that expose them to the relevant methodologies. Now that cheap (~10 USD), waterproof pouches for smart phones are widely available, there is the potential for mass acquisition of coral reef images by non-scientists. Furthermore, with the emergence of better machine-learning-based image classification approaches, high-quality data can be extracted from low-resolution images (provided that key benthic organisms, namely corals, other invertebrates, & algae, can be distinguished). To determine whether informally captured images could yield comparable ecological data to point-intercept + photo-quadrat surveys conducted by highly proficient research divers, we trained an artificial intelligence (AI), CoralNet, with images taken before and during a bleaching event in 2015 in Chagos (Indian Ocean). The overall percent coral covers of the formal, “gold standard” method and the informal, “tourist diver” approach of 38.7 and 35.1%, respectively, were within ~10% of one another; coral bleaching percentages of 30.5 and 31.8%, respectively, were statistically comparable. Although the AI was prone to classifying bleached corals as healthy in ~one-third of cases, the fact that these data could be collected by someone with no knowledge of coral reef ecology might justify this approach in areas where divers or snorkelers have access to waterproof cameras and are keen to document coral reef condition. Full article

In recent years, pervious oyster shell habitat (POSH) units have been developed and deployed as part of living shoreline projects in Northeast Florida. POSH units are modular artificial oyster reef structures made from cement and recycled oyster shells. POSH units aim to improve oyster recruitment, attenuate wave energy, trap sediment, and restore salt marsh habitat. Previous studies demonstrated the units’ ability to attract oyster larvae and reduce shoreline bed stress in some areas. This paper further explores the effect of POSH unit placement on bed stress under boat wake conditions using large-eddy simulations (LES). Results indicated that certain POSH unit arrangements may be preferable; a small overlap between segments may help block flow and reduce associated stresses, while a chevron pattern may benefit sites subject to oblique waves. However, even these more “optimized” configurations resulted in bed stresses with similar orders of magnitude when compared to more linear arrangements. Understanding how POSH units affect bed stress and potential erosion patterns can help restoration stakeholders design future living shorelines with POSH units or other similar structures. Full article

Coral reefs play a crucial role in tropical coastal ecosystems, even though these environments are difficult to monitor due to their diversity and morphological complexity and due to their shallowness in some cases. This study used two approaches for acquiring very-high-resolution bathymetric data: underwater structure-from-motion (SfM) photogrammetry collected from a low-cost platform and unmanned/uncrewed aerial vehicle (UAV)-based SfM photogrammetry. While underwater photogrammetry avoids the distortions caused by refraction at air/water interface, it remains limited in spatial coverage (about 0.04 ha in 1 h of survey). In contrast, UAV photogrammetry allows for covering extensive areas (more than 20 ha/h) but requires applying refraction correction in order to accurately compute bathymetry and roughness values. An analytical approach based on Snell laws and an empirical approach based on linear regression (calibrated using a batch of points whose depths are representative of the depth range of the surveyed areas) are tested to correct the apparent depth on the raw UAV digital elevation model (DEM). Comparison to underwater photogrammetry shows that correcting refraction reduces the root mean square error (RMSE) by more than 50% (up to 62%) on bathymetric models, with RMSE lower than 0.13 m for the analytical approach and down to 0.09 m for the regression method. The linear-regression-based refraction correction proved most effective in restoring accurate seabed roughness, with a mean error on roughness lower than 17% (vs. 30% for analytical refraction correction and 48% for apparent bathymetry). Full article

Reef restoration is the major way to compensate the loss of scleractinian corals, which requires huge amounts of transplantation donors. Previous study revealed that some species of corals can conduct polyp bailout and reattachment under environmental stress, which contributes to the living of coral communities and offer a novel way to produce numerous coral colonies for reef restoration. In the present study, physiological and transcriptomic approaches were conducted to illustrate the effects and molecular mechanisms of brine shrimp feeding on the newly attached polyps of coral Poccillopora damicornis. It was observed that brine shrimp feeding significantly prompted the growth of reattached polyps by elevating polyp diameter, number of new polyps, weight of the calcified skeleton, symbiont density, chlorophyll a + c₂ content and Ea values. Transcriptomic analysis also inferred that signaling pathways responsive for energy metabolism, cell growth and biomineralization were dramatically activated. Furthermore, brine shrimp feeding enhanced the immunity of the reattached polyps by suppressing caspase-3 activation level and elevating antioxidant capacity. These results collectively reveals the influence and detailed molecular mechanisms of brine shrimp feeding on the growth of newly reattached coral polyps, which shed light on the potential application of such methods in the cultivation of coral transplantation donors. Full article

Fears regarding the future of coral reefs are reflected in a growing scientific effort, worldwide, to help corals survive and adapt to the impacts of climate change through new management strategies. To be viable, these strategies must not only be ecologically beneficial and technically feasible; they must be developed in partnership with Indigenous peoples and sensitive to the needs and aspirations of local communities, stakeholders and broader publics. This paper synthesizes insights from a comprehensive program of qualitative and quantitative social research, conducted through Australia’s Reef Restoration and Adaptation Program, exploring local community and public perspectives on the Great Barrier Reef (GBR) and the prospect of assisted adaptation. While the results of this research indicate strong support for prospective interventions to help the GBR, they also demonstrate that local communities and the broader Australian public hold multiple visions for the GBR’s future and engage in careful processes to imagine and evaluate assisted adaptation. We discuss the implications of this complexity for the development of technically robust and socially responsible adaptation intervention in the GBR, emphasizing the opportunities it presents for robust and inclusive dialogue, knowledge building, and governance around these strategies. Community and public support, we conclude, is contingent on moving beyond the seemingly straightforward question of whether or not people support intervention and towards forms of engagement that allow space for social and cultural diversity and the co-creation of ethically grounded adaptation pathways. Full article

Coral reefs, with their high biodiversity and ecological service functions, face significant threats due to climate change, overfishing, and pollution. The South China Sea (SCS) hosts rich coral biodiversity, particularly Acropora hyacinthus, a critical species for reef restoration. However, the region’s coral reefs are increasingly degraded, highlighting the urgent need for conservation efforts. In the present study, the genetic diversity and population structure of A. hyacinthus were examined based on two types of data: double-digest restriction-site-associated DNA (ddRAD) sequencing data and mitochondrial putative control region DNA (mtCR) sequences. Coral tissue samples were collected from 74 colonies inhabiting two inshore reefs (Sanya) and three offshore reefs (Xisha islands), and 748 single nucleotide polymorphisms (SNPs) and 74 mtCR sequences were obtained and utilized for downstream analysis. The results were consistent in analyses and did not cluster into two geographical groups for the inshore and offshore sites. Phylogenetic analysis showed that individuals of A. hyacinthus inhabiting the five detected sites were likely cryptic species HyaD. Furthermore, AMOVA and pairwise F_ST estimations based on both data types revealed no differentiation among five populations and between inshore and offshore reefs, which could be due to the reproductive mode of broadcast spawning for this species. However, a prevalent low level of genetic diversity was observed when compared with nearby Taiwan regions and Japan, and the geographic history results showed that the effective population size (N_e) had been decreasing for the past 300 years. Thus, we speculated that the populations of A. hyacinthus inhabiting the SCS lack the potential to cope with future climate change adequately, and multiple conservation measures should be implemented based on considering genetic diversity. Full article

Acropora palmata, a keystone Caribbean coral species, is currently subject to intense restoration efforts across the region. Despite its known annual broadcast spawning, in situ monitoring of 33 colonies in Cozumel, Mexico, from 2018 to 2025 revealed a near-complete absence of spawning activity. While “setting” was occasionally observed, no simultaneous spawning events occurred among colonies, impeding assisted fertilization. This eight-year effort, involving academic institutions, government, NGOs, and the community, highlights the breakdown in reproductive synchrony of A. palmata. We discuss possible contributing factors, including artificial light, sedimentation, thermal anomalies, water quality and direct human impact. These findings demand immediate regional attention and investigation to identify the underlying causes of this reproductive failure. Full article

Oyster reefs are receiving increasing attention due to severe survival challenges and their significant ecological service functions. Despite increased restorations worldwide, both natural and restored reefs have often not been monitored to an extent. Reef-building oyster populations are the foundation for the development of oyster reefs. In order to provide basic data for further protection and potential restoration of the oyster reef in the muddy tidal flats of Magu Island, in the middle of Dingzi Bay, the population structure and genetic diversity of the reef-building oysters were assessed through field investigation and molecular experiments. Results showed that the area of the oyster reef was 20,689 square meters and the oysters were Magallana gigas. The distribution of oyster patches revealed a reef building-up stage. The mean densities of the oysters were 3260.80 ind·m⁻² and 3097.60 ind·m⁻² in spring and autumn, respectively, and the biomasses were 25,209.38 g·m⁻² and 30,137.44 g·m⁻². The frequent distribution of shell height indicated two primary sizes divided by ages. Population genetic analyses based on partial mitochondrial cox1, cox3, and nad2 showed low nucleotide diversity and moderate haplotype diversity, proposing the population growth stage. Both the results of the population structure and genetic diversity suggested a developing status of the oyster reef on Magu Island. Full article

In the face of recent setbacks to coral reef conservation and restoration due to intensifying marine heat waves, new coral-focused strategies have been developed to accelerate natural processes of coral reef adaptation and recovery. In 2024, these “Reefs of Hope” strategies were endorsed by UNESCO as an Ocean Decade. This paper shares the progress made and methods used and translates the new paradigm into a proposed national coral-focused adaptation plan using Fiji as an example. The primary goal of any coral-focused adaptation plan should be to keep coral species alive despite increasingly lethal temperatures due to ocean warming and, in doing so, to retain as much genetic diversity as possible. This is done by translocating corals locally to secure cooler-water gene bank nurseries, with a focus on heat-adapted, bleaching-resistant corals, which are vital to adaptation. Secondary goals are to restore sexual reproduction to declining and rare coral species and to support natural larval-based recovery and adaptation processes via the creation of “regeneration patches”, which enhance and restore natural recovery processes while facilitating the spread of heat-adapted genetic diversity of both host and symbionts. The proposed plans create a new model of proactive coral-focused adaptation that other reef-owning nations might study, modify to national conditions, and seek funding to implement. These Fiji-based plans are now ready for the next step of national stakeholder input and refinements toward approval by the government and the coral reef conservation community. Full article

The literature on resilience-building in the Great Barrier Reef (GBR) is predominated by institutional voices. Although community involvement is appreciated in this scholarship, the perspectives are mainly those of scientists and researchers. Community input is used mainly to inform and strengthen academic findings, and there are few articles in the voices and words of GBR community members. Our opinion piece, with its majority co-authorship by the Stakeholder Advisory Group of Australia’s Reef Restoration and Adaptation Program (RRAP), addresses this literary gap. The piece draws upon the barriers to involvement in adaptation delivery as experienced by these GBR locals who have diverse backgrounds related to reef adaptation, including aquaculture, tourism, robotics, natural resource management, civil society, policy and Traditional Owner-led environmental stewardship. Currently, the social capital of communities is underutilised in GBR intervention delivery. However, with the urgency for action in the Reef, we call on governments and researchers to leverage the expertise, labour and infrastructure of local communities to strengthen institutional deployment capacities and thereby accelerate the scale and impact of adaptation efforts. We identify the key elements of inclusive deployment as shared leadership, flexible and inclusive funding, and innovative strategies to address permitting and regulatory barriers to community-led interventions deployment. Full article

Artificial reefs serve as a crucial measure for preventing habitat degradation, enhancing primary productivity in marine areas, and restoring and increasing fishery resources, making them an essential component of marine ranching development. Accurate identification and detection of artificial reefs are vital for ecological conservation and fishery resource management. To achieve precise segmentation of artificial reefs in multibeam sonar images, this study proposes an improved YOLOv11-based model, YOLO-AR. Specifically, the DCCA (Dynamic Convolution Coordinate Attention) module is introduced into the backbone network to reduce the model’s sensitivity to complex seafloor environments. Additionally, a small-object detection layer is added to the neck network, along with the ultra-lightweight dynamic upsampling operator DySample (Dynamic Sampling), which enhances the model’s ability to segment small artificial reefs. Furthermore, some standard convolution layers in the backbone are replaced with ADown (Advanced Downsampling) to reduce the model’s complexity. Experimental results demonstrate that YOLO-AR achieves an mAP@0.5 of 0.912, an intersection-over-union (IOU) of 0.832, and an F1 score of 0.908. Meanwhile, the parameters and model size of YOLO-AR are 2.67 million and 5.58 MB. Compared to other advanced segmentation models, YOLO-AR maintains a more lightweight structure while delivering a superior segmentation performance. In real-world multibeam sonar images, YOLO-AR can accurately segment artificial reefs, making it highly effective for practical applications. Full article

Coral reefs in Arabian Gulf and Gulf of Oman waters of the United Arab Emirates (UAE) have historically been dominated by Acropora corals. By early 2021, however, extensive Acropora cover remained at only two UAE locations: the fringing reefs of Sir Bu Nair Island (SBN) (Arabian Gulf) and Khor Fakkan (KF) (Gulf of Oman). A summer 2021 marine heatwave impacted these last Acropora refugia and caused the first mass bleaching event on the UAE’s Gulf of Oman coast. Benthic surveys were conducted before, during and eight months after this event. Bleaching severity was high, with 41% of hard corals bleached in KF and 93% in SBN. Total live coral cover declined from 68% to 25% at KF and from 36% to 9% in SBN during bleaching. Acropora cover declined from 23% to 2% in KF and from 19% to 0.02% in SBN during bleaching. There was limited recovery eight months after bleaching. Community composition shifted away from Acropora toward heat-tolerant taxa, particularly Porites and Dipsastraea, with increased homogenization of coral assemblages. These last Acropora refugia could have served as valuable sources of larvae to support coral recovery elsewhere in UAE waters, highlighting the importance of conservation and restoration efforts. Full article

Shallow warm-water coral reefs are among the most biodiverse and valuable ecosystems on Earth, supporting a quarter of all marine life and delivering critical ecosystem services such as coastal protection, food security, and economic benefits through tourism and fisheries. However, these ecosystems are under escalating threat from anthropogenic climate change, with tropical cyclones representing their most significant high-energy storm disturbances. Approximately 70% of the world’s coral reefs lie within the tropical cyclone belt, where the frequency, intensity, and rainfall associated with tropical cyclones are changing due to global warming. Coral reefs already compromised by climate-induced stressors—such as marine heatwaves, ocean acidification, and sea-level rise—are increasingly vulnerable to the compounding impacts of more intense and slower-moving cyclones. Projected changes in cyclone behaviour, including regional variations in storm intensity and rainfall, may further undermine coral reef resilience, pushing many reef systems toward irreversible degradation. Future impacts will be regionally variable but increasingly severe without immediate climate mitigation. Building reef resilience will require a combination of rapid global carbon emission reductions and ambitious adaptation strategies, including enhanced reef management and restoration and conservation efforts. The long-term survival of coral reefs now hinges on coordinated global action and support for reef-dependent communities. Full article