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The construction of artificial reefs (ARs) is an effective way to restore habitats and increase and breed fishery resources in marine ranches. However, studies on the impacts of ARs on the structure, function, and assembly patterns of the bacterial community (BC), which is important in biogeochemical cycles, are lacking. The compositions, diversities, assembly patterns, predicted functions, and key environmental factors of the attached and free-living microbial communities in five-year ARs (O-ARs) and one-year ARs (N-ARs) in Fangchenggang, China, were analyzed via 16S rRNA gene sequencing. Proteobacteria was the dominant taxon in all the samples, with an average relative abundance of 44.48%, followed by Bacteroidetes (17.42%) and Cyanobacteria (15.19%). The composition of bacterial phyla was similar between O-ARs and N-ARs, but the relative abundance of Cyanobacteria was greater in the water column (38.56%) than on the AR surface (mean of 7.40%). The results revealed that the Shannon‒Wiener diversity indices were 5.64 and 5.45 for O-ARs and N-ARs, respectively. Principal coordinate analysis (PCoA) revealed different distributions of O-ARs and N-ARs in the microbial community. Additionally, network analysis revealed that the bacterial community was more complex and stable in O-ARs than in N-ARs, indicating that the 5-year AR presented a more diverse and stable microbial community overall. The KEGG database was used to predict that nitrogen metabolism, carbon metabolism, and membrane transport were the dominant microbial functions, accounting for 29.93% of the total functional abundances. The results of the neutral community model revealed that stochastic processes (67.2%) dominated the assembly of BCs. Interestingly, deterministic processes may be increasingly important in community aggregation over time. Moreover, a null model revealed that dispersal limitation was the most important process among the stochastic processes, accounting for 57.14% of the total. In addition, redundancy analysis (RDA) revealed that hydrological factors obviously impacted the structure and function of the microbial community. Our results showed that the construction of ARs slightly promotes local diversities in the structure and function of the microbial community, indicating it requires a longer time to enhance the diversity of the microbial community on artificial reefs. Key points: • Artificial reefs facilitate the diversity and functions of the microbial community • Stochastic processes dominate the assembly of the microbial community in artificial reefs • Nitrogen and carbon metabolism dominate microbial functions in artificial reefs [ABSTRACT FROM AUTHOR]

Artificial reefs may be created within estuaries for multiple reasons, including habitat enhancement, oyster production, or recreational fishing. While traditional sampling in this environment is difficult due to complex structures and the high turbidity of estuaries, acoustic imaging sonar provides an effective alternative to measure abundance and size spectra of the fish community. We sampled eight artificial reefs in Pamlico Sound, North Carolina, that are designated as oyster sanctuaries. At each oyster sanctuary, we sampled 26 boat positions along two transects using ARIS imaging sonar, which included control areas outside of the sanctuaries over featureless bottom. We found that fish abundance and mean length were greater within the oyster sanctuary boundaries, but did not observe any significant differences among artificial substrate types within the sanctuaries. Further, we found that fish abundance dropped to near background levels within 25 m outside of the oyster sanctuary edge. Size spectra analysis revealed that abundance was higher in the sanctuaries versus control areas for every length bin of the fish community (5 to 50 cm). However, the differences in abundance were greatest for 10 to 30 cm fishes. Our results can be coupled with previous research on species composition data to more fully understand the potential role that the Pamlico Sound oyster sanctuaries, and estuarine artificial reefs in general, serve as habitat and recreational fishing enhancement. [ABSTRACT FROM AUTHOR]

The relationship between biodiversity and ecosystem functioning (BEF) is one of the central themes of ecological research. Phytoplankton play important ecological functions in aquatic ecosystems. Although the BEF in phytoplankton communities was found in various types of natural aquatic ecosystems, it has not been examined in artificial ecosystems at small scale. Artificial reef, a submerged device built by human, can pump nutrient-rich bottom water to the surface, mimicking natural upwelling to feed phytoplankton. Here we quarterly investigated the phytoplankton communities in the artificial reef zone and its adjacent water in a subtropical bay. Our results showed positive linear relationship of phytoplankton richness to productivity in the artificial reef zone. The slope of richness-productivity relationship increased with water temperature and was relatively higher in the summer. Phytoplankton resource use efficiency (RUE) was positively correlated with richness but negatively correlated with evenness in the artificial reef zone. Compared to the adjacent natural zone, the artificial reef zone had more diverse phytoplankton communities and higher productivity during the growing season. The phytoplankton BEF pattern we found provides evidence for the role of artificial reef in the functioning of subtropical bay ecosystem. [ABSTRACT FROM AUTHOR]

ABSTRACT Gillnets are the most commonly used fishing gear targeting black rockfish (Sebastes schlegeli) and fat greenling (Hexagrammos otakii) in the artificial reef area in coastal China. However, a minimum mesh size (MMS) has not yet been established for this fishery, which is unfavorable for sustainable development and effective management of fishery resources. We compared size selectivity and catch efficiency of gillnets of four commonly used mesh size (stretched mesh size; 40, 50, 60, and 70‐mm) in a typical artificial reef area in the Yellow Sea, China. Increasing the mesh size improved size selectivity of gillnets for black rockfish and fat greenling by reducing the proportion of undersized individuals. Further, changes in mesh size affected catch efficiency of target‐sized individuals. To protect juveniles, while maintaining catch efficiency for target‐sized fish, we recommend 60‐mm as the MMS for this fishery. Our study will contribute to the development of MMS regulations in reef fisheries management in China. [ABSTRACT FROM AUTHOR]

Aims Artificial reefs play a vital role in restoring and creating new habitats for marine species by providing suitable substrates, especially in areas where natural substrates have been degraded or lost due to declining water quality, destructive fishing practices, and coral diseases. Artificial reef restoration aimed at coral larval settlement is gaining prominence and initially depends on the development of biofilms on reef surfaces. In this study, we hypothesized that different artificial reef materials selectively influence the composition of biofilm bacterial communities, which in turn affected coral larval settlement and the overall success of coral rehabilitation efforts. To test this hypothesis, we evaluated the impact of six different reef-made materials (porcelain, granite, coral skeleton, calcium carbonate, shell cement, and cement) on the development of biofilm bacterial communities and their potential to support coral larval settlement. Methods and results The biofilm bacterial communities were developed on different artificial reef materials and studied using 16S rRNA gene amplicon sequencing and analysis. The bacterial species richness and evenness were significantly (P  < 0.05) low in the seawater, while these values were high in the reef materials. At the phylum level, the biofilm bacterial composition of all materials and seawater was majorly composed of Pseudomonadota, Cyanobacteria , and Bacteroidetes ; however, significantly (P  < 0.05) low Bacteroidetes were found in the seawater. At the genus level, Thalassomonas, Glaciecola, Halomicronema, Lewinella, Hyphomonas, Thalassospira, Polaribacter , and Tenacibaculum were significantly (P  < 0.05) low in the coral skeleton and seawater, compared to the other reef materials. The genera Pseudoaltermonas and Thalassomonas (considered potential inducers of coral larval settlement) were highly abundant in the shell-cement biofilm, while low values were found in the biofilm of the other materials. Conclusion The biofilm bacterial community composition can be selective for different substrate materials, such as shell cement exhibited higher abundances of bacteria known to facilitate coral larval settlement, highlighting their potential in enhancing restoration outcomes. [ABSTRACT FROM AUTHOR]

Tropical seagrass ecosystems are globally imperiled due to overfishing and anthropogenic disturbances. Sustaining the services they provide will require managing resilience, particularly with increased volatility from climate change. Portfolio theory is touted as a mechanism to increase resilience in ecosystems because it takes advantage of temporal volatility in local production dynamics to increase stability at larger spatial scales. Using an individual‐based model of a network of artificial reefs across multiple seagrass ecosystems that is parameterized with 15 years of field data, we demonstrate that (1) the large fish populations and the low enrichment synergistically increase portfolio effects; (2) the mechanism was via reduced local and increased meta‐ecosystem stability in primary production; and (3) stability was greatest under intermediate production because nutrient enrichment reduces and fish, which have less influence on the amount of production, promote stability. Integrating common‐sense management with portfolio theory can stabilize the services provided by seagrass ecosystems. [ABSTRACT FROM AUTHOR]

The threat of declining seaweed beds has been a concern around the world. Seagrass and seaweed (brown algae) beds are essential habitats supporting fisheries. However, approximately 22% of these habitats have been lost in Japan due to increased coastal landfill sites and ports. This study aims to rehabilitate the depletion of these habitats by constructing an artificial reef in Wakasa Bay, Japan, and monitoring Sargassaceae succession in the second and fourth years after the construction was completed. In this study, we set up four sites on the artificial reef. Then we identified the seaweed species composition and coverage of the Sargassaceae using underwater visual observation by scuba divers. The seaweed coverage was already over approximately 80% in the second year after construction. The Sargassum horneri and S. confusum dominated during the first and second sampling in the second year after construction, and Myagropsis myagroides and S. patens during the third and fourth sampling in the fourth year after construction. Thus, the recovery of species composition takes longer than that of coverage. Therefore, observing species composition recovery is essential when constructing the artificial reef. [ABSTRACT FROM AUTHOR]

Artificial reefs are widely recognized for their role in improving the ecological environment and creating protected habitats for marine organisms, ultimately enhancing biodiversity within the food web and fisheries resources. This study utilizes stable isotopes to analyze fish samples ranging from 3.4 to 1067 g in body mass, collected within the artificial reef area of Haizhou Bay. The objective is to determine if the δ15N-based fish body mass acts as a driving factor in shaping the food web structure. The results showed a certain level of overlap among all trophic guilds, suggesting that most trophic guilds within this region share similar living environments and feeding habits. The multiple linear regression showed a slight increasing trend between δ15N values and body mass. Furthermore, the predator–prey mass ratio (PPMR) was calculated to be 430:1 based on the δ15N–body mass relationship. This implies that larger reef fish within this artificial reef ecosystem tend to have higher δ15N values compared to smaller fish, indicating a shorter food chain in this ecosystem. In summary, this analysis provides valuable insights into the fish community structure within artificial reef ecosystems. Therefore, it is recommended that future studies focus on further characterizing the fish community structure using body mass information. [ABSTRACT FROM AUTHOR]

The success and cost‐effectiveness of kelp forest restoration hinges on understanding the colonization ecology of kelps, particularly with respect to dispersal potential, recruitment success, and subsequent establishment. To gain needed insight into these processes we examined spatial patterns and temporal trajectories of the colonization of a large artificial reef by the giant kelp Macrocystis pyrifera. The 151 ha artificial reef complex was constructed in three phases over 21 years, enabling dispersal, recruitment, and subsequent establishment to be examined for a wide range of environmental conditions, dispersal distances, and source population sizes. Natural colonization of all phases of the artificial reef by giant kelp was rapid (within 1 year) and extended across the entire 7‐km‐long reef complex. Colonization density declined with distance from the nearest source population, but only during the first phase when the distance from the nearest source population was ≤3.5 km. Despite this decline, recruitment on artificial reef modules farthest from the source population was sufficient to produce dense stands of kelp within a couple of years. Experimental outplanting of the artificial reef with laboratory‐reared kelp embryos was largely successful but proved unnecessary, as the standing biomass of kelp resulting from natural recruitment exceeded that observed on nearby natural reefs within 2–3 years of artificial reef construction for all three phases. Such high potential for natural colonization following disturbance has important implications for kelp forest restoration efforts that employ costly and logistically difficult methods to mimic this process by active seeding and transplanting. [ABSTRACT FROM AUTHOR]

Abstract Artificial reefs (AR), which are integral tools for fish management, ecological reconciliation and restoration efforts, require non-polluting materials and intricate designs that mimic natural habitats. Despite their three-dimensional complexity, current designs nowadays rely on empirical methods that lack standardised pre-immersion assessment. To improve ecosystem integration, we propose to evaluate 3-dimensional Computer-aided Design (3D CAD) models using a method inspired by functional ecology principles. Based on existing metrics, we assess geometric (C-convexity, P-packing, D-fractal dimension) and informational complexity (R-specific richness, H- diversity, J-evenness). Applying these metrics to different reefs constructed for habitat protection, biomass production and bio-mimicry purposes, we identify potential complexity target points (CTPs). This method provides a framework for improving the effectiveness of artificial reef design by allowing for the adjustment of structural properties. These CTPs represent the first step in enhancing AR designs. We can refine them by evaluating complexity metrics derived from 3D reconstructions of natural habitats to advance bio-mimicry efforts. In situ, post-immersion studies can help make the CTPs more specific for certain species of interest by exploring complexity-diversity or complexity-species distribution relationships at the artificial reef scale.

Imaging sonars (ISs) are high-frequency acoustic devices that are increasingly being used to study fish in marine and freshwater habitats. Acoustic devices are limited in quantifying species richness, and previous attempts to identify fish species using IS have mostly focused on assemblages of low species richness or high morphological diversity. This study aimed to determine the ability of IS for identifying fish species at a subtropical artificial reef off Perth, Western Australia. Several fish traits that could be defined using IS were identified and described for all fish species observed with simultaneous optical footage. These traits were used to create a clustering algorithm to infer the species identity of IS detections of the five most abundant species at the reef. The identities of all fish from two species (Chromis westaustralis and Neatypus obliquus) were inferred with 100% success, though no individuals from the remaining three species (Seriola dumerili, Coris auricularis , and Pempheris klunzingeri) were correctly identified. An alternative clustering-based approach to categorising fish detected by IS independent of taxonomic inference was also implemented. Overall, this study demonstrates that IS can identify reef fish with variable success, and proposes an alternative method for describing fish assemblages irrespective of species identity. [ABSTRACT FROM AUTHOR]

Artificial reefs featuring different shapes and functions have been deployed around the world, causing impacts on marine ecosystems. However, the approaches typically used to deliver topological complexity, flexibility and expanding requirements to prospective structures during the initial design stages are not well established. The aim of this study was to highlight the advantages and provide evidence on how modularity and parametric design can holistically leverage the performance of multifunctional artificial reefs (MFARs). In particular, the goal was to develop a parametric design for MFAR and establish a direct relationship between specific design parameters and the MFAR target functions or design requirements. The idea of implementing the parametric design for generating the initial biomimetic geometry of the individual modular unit was explored. Furthermore, possible ways of manipulating the geometric parameters of the individual module and the whole assembly were proposed. The findings suggest that, by adopting the developed procedure and the examples studied, several functions may be reached within a single assembly: the promotion of marine biodiversity restoration, the support of scientific platforms with various sensors, as well as the development of recreational diving and of touristic attraction areas. Acquired knowledge suggests that the concept of a nature-like design approach was developed for artificial reefs with varying scales, complexity and functions, which widens the range of possibilities of how smart design of human-made underwater structures may contribute to benefiting the near shore ecosystems. [ABSTRACT FROM AUTHOR]

Context: In Western Australia, the heritage-listed Busselton Jetty is a popular tourism, fishing and diving destination renowned for its unique marine communities. Aims: This research describes and quantifies the fish assemblages (mean number of individuals, species diversity and biomass) at the Busselton Jetty, and makes comparisons with natural habitats in Geographe Bay. Methods: Diver-operated stereo-video systems filmed 25-m transects along the length of the jetty, and a remotely operated vehicle stereo-video filmed 25-m transects in nearby reef, seagrass and sand habitats. Fish at all habitats were counted, identified and measured. Results: Fish assemblages at the defined inshore, mid-shore and offshore zones of the jetty differed significantly, whereas the number of fish, species diversity and biomass increased with distance from shore. There was no measurable effect of protection within the small sanctuary zone at the end of the jetty. Fish assemblages at the jetty differed from those in all three natural habitats, and the number of fish, species diversity and biomass were highest at the natural reef, followed by the jetty, the seagrass and the sand habitats. Conclusions: The Busselton Jetty supports a distinctive fish assemblage, high species diversity and a variety of benthic communities. Changes in the fish assemblages were attributed to differences in habitat type, complexity, depth and distance from shore. Implications: The ecological and social benefits of future man-made marine structures can be optimised by incorporating design features that promote habitat diversity and complexity. We described and quantified the fish assemblages at the heritage-listed Busselton Jetty, and made comparisons with natural reef, seagrass and sand habitats in Geographe Bay. The mean number of fish, species diversity and biomass all increased with distance along the jetty. The fish assemblage at the jetty was unique and different from that in all three natural habitats. Habitat complexity, depth and distance from shore were the key drivers of these differences. [ABSTRACT FROM AUTHOR]

AbstractThe corrosion of concrete and environmental pollution have become major challenges for the conventional concrete used in sea beds. Comprehensive research work has been carried out to enhance the strength and effectiveness of artificial reef (AR) concrete, because of its significant benefits for the sea coastlines to enhance algae growth, fish assembly, rehabilitation, and soil erosion. An experimental investigation of the compressive strength, water absorption, flexural, split tensile strength, and sorptivity of concrete specimens used for artificial reefs concrete immersed in seawater is presented here. Natural recycled materials used in this research work includes fly ash, seashells, rice-husked ash, silica fumes, granite powder, paper pulp, and coconut fiber. To investigate the corrosion behaviors of concrete based on the M20 standard, experiments were conducted using different proportions of raw materials. Concrete strength was observed on different days (7, 14, 28, 56, and 90) and the results showed that artificial reef concrete is stronger than conventional concrete. Moreover, the strength of concrete is increased by 3% due to the addition of 5% of silica fume and granite powder. It also shows that the attack of sulfate in the concrete decreases gradually by the addition of rice husk ash and silica fume. In addition to other recycled biodegradable materials like AR2, AR3, and AR4 have flexural strengths such as 1.90%, 4.08%, and 5.07% which is higher than the conventional concrete, respectively. These approaches were eco-friendly to the ocean, because of the application of silica fumes and flyash and it does not create any type of crack in the reef. It is cost-effective and environmentally favorable. The splitting tensile strength of the traditional mixer after 28 days is measured in 2.94 MPa, which was found to be 2.11%, 4.79%, 4.68%, 23.81%, and 28.78% and it is higher than the values observed in the other specimens. [ABSTRACT FROM AUTHOR]

Offshore oil and gas platforms support abundant reef fish and are popular fishing sites for recreational anglers. However, the rapid decommissioning and removal of active platforms have decreased such fishing opportunities in the Gulf of Mexico, raising concerns about fisheries impacts. Conversely, planned offshore energy structures like wind turbines may offer similar habitats and fishing sites. To inform spatial planning for marine energy infrastructure in the context of recreational fisheries, we created models of fish communities associated with oil and gas platforms using existing abundance data. We employed Random Forest analysis to predict the presence‐absence and abundance of Red Snapper (Lutjanus campechanus) and Greater Amberjack (Seriola dumerili) at platforms using 47 environmental and platform variables. Nonmetric multidimensional scaling on Bray−Curtis dissimilarities explored fish species composition among 37 species. Results showed variability in Red Snapper and Greater Amberjack incidence/abundance from shore to shelf‐edge, not attributed to surrounding habitat or climatological oceanographic variables. Incidence models were more robust than abundance models. Fish species composition was significantly influenced by location gradient, with less impact from other habitat features. Our findings guide selecting areas for artificial structures to enhance angler opportunities and maintain fish diversity, but identifying the drivers of finer scale abundance variation will require further sampling. [ABSTRACT FROM AUTHOR]

In recent years, with the scale and standardization of Stichopus japonicus mariculture, artificial reefs are increasingly used in S. japonicus farming to promote the development of the S. japonicus aquaculture industry. To provide shelter and improve the habitat environment for S. japonicus, three types of artificial reefs (box-shaped reef, triangular-shaped reef, and trapezoidal-shaped reef) were designed according to the ecological habitats of S. japonicus and the marine environment of Haizhou Bay (China) in the present study. After comprehensively comparing the three reef structures, we found that the trapezoidal-shaped reef has good permeability, a larger attachment area, and excellent anti-slip and anti-overturning properties. Further, the flow field characteristics surrounding a trapezoidal-shaped reef at different angles and flow velocities are investigated by three-dimensional numerical simulations. Then, the impact of the placement distance on the flow field surrounding the artificial reef combination was investigated. At the head-on angle θ = 0°, the upwelling volume increases as the flow velocity increases and then decreases, and the back eddy volume remains relatively constant. At the longitudinal spacing D = 4 L, the large slow-flow area surrounding the reef under this condition is more suitable for the S. japonicus habitat. In this study, the trapezoidal-shaped reef design is suitable and beneficial for S. japonicus aquaculture. Moreover, this study will contribute theoretical references to the design and arrangement of artificial reefs in coastal areas. [ABSTRACT FROM AUTHOR]

Artificial reefs may be created within estuaries for multiple reasons, including habitat enhancement, oyster production, or recreational fishing. While traditional sampling in this environment is difficult due to complex structures and the high turbidity of estuaries, acoustic imaging sonar provides an effective alternative to measure abundance and size spectra of the fish community. We sampled eight artificial reefs in Pamlico Sound, North Carolina, that are designated as oyster sanctuaries. At each oyster sanctuary, we sampled 26 boat positions along two transects using ARIS imaging sonar, which included control areas outside of the sanctuaries over featureless bottom. We found that fish abundance and mean length were greater within the oyster sanctuary boundaries, but did not observe any significant differences among artificial substrate types within the sanctuaries. Further, we found that fish abundance dropped to near background levels within 25 m outside of the oyster sanctuary edge. Size spectra analysis revealed that abundance was higher in the sanctuaries versus control areas for every length bin of the fish community (5 to 50 cm). However, the differences in abundance were greatest for 10 to 30 cm fishes. Our results can be coupled with previous research on species composition data to more fully understand the potential role that the Pamlico Sound oyster sanctuaries, and estuarine artificial reefs in general, serve as habitat and recreational fishing enhancement.

Aquaculture is the fastest growing food production industry. The Chinese mariculture industry has made great progress in the past 40 years to become the dominant producer of aquaculture. However, the current deterioration of the water environment and the aggravation of farming diseases poses challenges for the traditional culture model to meet the new requirements of healthy development in marine fishery resources. This problem was addressed using marine ranching. This is a new mariculture model that includes two approaches (artificial reefs and stocking) with the goal of achieving environmental and ecological harmony. Artificial reefs are an important component of this marine ranching model since they can help improve the water environment around the reefs, promote nutrient circulation, provide a suitable habitat for marine organisms, and encourage colonization of the reef surface by sessile organisms. The placement of artificial reefs into seawater may serve as a substrate for bacteria to form a biofilm on the surface. Biofilms play a crucial role in the settlement of many marine invertebrate species. However, limited research was conducted into the relationship between bacteria on the surface of artificial reefs, biofilm formation, and the settlement behavior of Mytilus coruscus.This study placed white acrylic plates and tetrahedral structured artificial reefs in Gouqi Island, Zhoushan City, Zhejiang Province, China (122°46′ E; 30°43′ N). Nine strains of bacteria isolated from the surface of the artificial reefs were used to construct mono-species bacterial biofilms and induce plantigrade settlement of M. coruscus. The aim of the study was to investigate the interactions between marine bacteria and the settlement of M. coruscus on the surface of artificial reefs. The marine biofilms impacted the settlement process of M. coruscus. The bacterial species from the marine biofilm were screened for high and low inducing activity and analyzed for bacterial density, protein, and polysaccharide content to further explore the relationship between different bacterial biofilms and M. coruscus settlement.There were significant differences in the induction activity of biofilms formed by the nine strains of artificial reef bacteria on the settlement of M. coruscus: Mesoflavibacter sp.2 and Phaeobacter sp.2 showed the highest and lowest induction activity, respectively. Bacteria within the same genus exhibited differences in induction activity. This indicated that the induction activity of bacterial biofilms on mussel settlement was independent of bacterial species. Phylogenetic analysis showed that genetically similar strains (such as Pseudoalteromonas sp.31 and Pseudoalteromonas sp.32) and genetically distant strains (such as Mesoflavibacter sp.2 and Jeotgalibacillus sp.1) showed significant differences in the induction activity of M. coruscus settlement. Only four of the nine bacterial strains showed significant correlation between biofilm density and the settlement rate. Sutcliffiella sp.1 and Jeotgalibacillus sp.1 exhibited a positive correlation between bacterial density and induction activity. This indicated that bacterial density may play a role in M. coruscus settlement, although it may be strain specific. Additionally, the trend of induction activity of mussel larvae attachment varied with increasing initial bacterial density. The optimal density for settlement is strain specific. Further analysis of biofilm active substance content in Mesoflavibacter sp.2 and Phaeobacter sp.2 revealed that polysaccharide content negatively correlated with induction activity of M. coruscus and positively correlated with protein content. This suggests that bacterial species may not directly affect M. coruscus settlement, although bacteria may indirectly influence settlement by affecting the secretion of extracellular products.This study showed that nine bacterial strains had significant differences in their ability to induce mussel settlement on the surface of artificial reefs. Interestingly, these differences did not necessarily correlate with the genetic distance between the marine bacteria. Further investigations were conducted on two selected strains of bacteria (Mesoflavibacter sp.2 and Phaeobacter sp.) that exhibited different levels of inductive activity on M. coruscus. The polysaccharide content and protein content negatively and positively correlated with the induction activity of M. coruscus, respectively. This suggests that the presence of specific polysaccharides may negatively affect the settlement of M. coruscus according to cellulose content measurements.This is the first study investigating the effect of bacteria on M. coruscus settlement on the surface of artificial reefs. This has significant theoretical implications for further research on the interactions between biofilms and marine invertebrates on the surface of artificial reefs in natural marine environments. Understanding the settlement mechanisms of marine benthic organisms on artificial reefs is crucial to manage and conserve marine resources since artificial reefs are widely used to enhance marine habitat and biodiversity. The findings of this study have practical implications for the design and construction of artificial reefs. Understanding the role of bacteria in mussel settlement facilitates the optimization of artificial reef structures to promote or inhibit the settlement of target species. This knowledge can help develop effective strategies to manage biofouling on artificial reefs. This can impact the performance and longevity of these structures. Further research in this field will deepen our understanding of the underlying mechanisms and enable development of management strategies for artificial reefs and marine conservation efforts.

The present study was conducted to investigate the behavior and distribution characteristics of fishes near an artificial reef close to the waters of Uljin marine ranch. A 200-kHz, dual-beam frequency transducer was attached to the side of a ship for acoustic measurements. The fish formed small groups in the bottom layer near the artificial reef around the afternoon-sunset period; at night, the fish did not form groups and remained individually scattered. During dawn-sunrise and morning, the fish formed groups again and were found near the upper and middle layers of the artificial reef. High density of fish occurred near the middle of the nautical zone during morning, afternoon-sunset, and dawn-sunrise, periods; at nighttime, the distribution was uniform across the entire zone. Moreover, the mean Nautical Area Scattering Coefficients (NASC, m2/nmi2) value was highest during dawn-sunrise at 400.2 m2/nmi2, similar during night and morning (100.5 m2/nmi2), and lowest during afternoon-sunset (20.1 m2/nmi2). The present study is expected to provide the background for understanding the behavioral characteristics of fish living near artificial reefs and estimating the density and biomass of fish.

Artificial reefs can play an important role in marine fisheries management by supplementing or enhancing natural habitats. Despite their increased use in recent years, the choice of structures used at artificial reefs remains largely haphazard due to the lack of information on reef structure performance. Few studies have examined the use of different artificial reef structures by individual fish. From 2021-2022, we acoustically tagged 72 black sea bass (Centropristis striata), 34 gag (Mycteroperca mircrolepis), 27 greater amberjack (Seriola dumerili), nine almaco jack (S. rivoliana), and eight red snapper (Lutjanus campechanus) on four artificial reef complexes near Cape Lookout, North Carolina, U.S. Available artificial reef structures consisted of materials of various sizes and heights made of concrete and metal. We tracked tagged fish using a fine-scale positioning system for ~100 days. Black sea bass exhibited high site fidelity to the artificial structure where we caught them, rarely moving away from that structure. The limited movement resulted in low transition probabilities; we conclude that black sea bass do not select for particular artificial structures. Gag and red snapper moved greater distances away from artificial structures and routinely moved between them. Greater amberjack and almaco jack moved the most within the complexes displaying circling behavior around individual structures and were the only species that regularly moved off the artificial reef complexes. Greater amberjack movements away from artificial sites were most commonly directed to surrounding shipwrecks. Whereas gag, red snapper, almaco jack, and greater amberjack used all available structures, they consistently selected for high relief structures, such as vessels, more than other structures. These results will be useful to managers charged with decisions on what types of structures to place at artificial reef complexes to supplement or enhance habitat for economically important fishes. [ABSTRACT FROM AUTHOR]

On the basis of computational fluid dynamics, the flow field characteristics of multi-trophic artificial reefs, including the flow field distribution features of a single reef under three different velocities and the effect of spacing between reefs on flow scale and the flow state, were analyzed. Results indicate upwelling, slow flow, and eddy around a single reef. Maximum velocity, height, and volume of upwelling in front of a single reef were positively correlated with inflow velocity. The length and volume of slow flow increased with the increase in inflow velocity. Eddies were present both inside and backward, and vorticity was positively correlated with inflow velocity. Space between reefs had a minor influence on the maximum velocity and height of upwelling. With the increase in space from 0.5 L to 1.5 L (L is the reef lehgth), the length of slow flow in the front and back of the combined reefs increased slightly. When the space was 2.0 L, the length of the slow flow decreased. In four different spaces, eddies were present inside and at the back of each reef. The maximum vorticity was negatively correlated with space from 0.5 L to 1.5 L, but under 2.0 L space, the maximum vorticity was close to the vorticity of a single reef under the same inflow velocity. [ABSTRACT FROM AUTHOR]

Abstract Offshore oil and gas platforms support abundant reef fish and are popular fishing sites for recreational anglers. However, the rapid decommissioning and removal of active platforms have decreased such fishing opportunities in the Gulf of Mexico, raising concerns about fisheries impacts. Conversely, planned offshore energy structures like wind turbines may offer similar habitats and fishing sites. To inform spatial planning for marine energy infrastructure in the context of recreational fisheries, we created models of fish communities associated with oil and gas platforms using existing abundance data. We employed Random Forest analysis to predict the presence‐absence and abundance of Red Snapper (Lutjanus campechanus) and Greater Amberjack (Seriola dumerili) at platforms using 47 environmental and platform variables. Nonmetric multidimensional scaling on Bray−Curtis dissimilarities explored fish species composition among 37 species. Results showed variability in Red Snapper and Greater Amberjack incidence/abundance from shore to shelf‐edge, not attributed to surrounding habitat or climatological oceanographic variables. Incidence models were more robust than abundance models. Fish species composition was significantly influenced by location gradient, with less impact from other habitat features. Our findings guide selecting areas for artificial structures to enhance angler opportunities and maintain fish diversity, but identifying the drivers of finer scale abundance variation will require further sampling.

The degradation of marine resources at Samasarn Islands has been a problem for a long time. Due problem, a fish dome was established on Samae San Island, with the objective of serving as a resource for future marine ecosystem rehabilitation. Over a 25-month, from March 2018 to March 2020, studies on the composition and abundance of marine fish were collected from fish domes. A video census method was collected from 100 fish domes situated across five stations. Each station was further divided into five groups, each containing four fish domes. Found 99 species belonging to 36 different families. The Pomacentridae family was the most dominant with 11 species, followed closely by Labridae and Gobiidae families, each with 8 species. Intriguingly, the research unveiled the presence of at least seven fish species within the fish dome area that had not been previously observed in the coral reefs of Samaesarn Island. These species include Janss' pipefish (Doryrhamphus janssi), spotted porcupinefish (Diodon hystrix), map puffer (Arothron mappa), half-barred goby (Priolepis semidoliata), bearded leatherjacket (Anacanthus barbatus), spotcheek emperor (Lethrinus rubrioperculatus), and three-striped whiptail (Pentapodus trivittatus). This study showed the importance of fish domes for the restoration of coral reefs, especially for coral reef fish and marine fish in this area.

Artificial reefs can play an important role in marine fisheries management by supplementing or enhancing natural habitats. Despite their increased use in recent years, the choice of structures used at artificial reefs remains largely haphazard due to the lack of information on reef structure performance. Few studies have examined the use of different artificial reef structures by individual fish. From 2021-2022, we acoustically tagged 72 black sea bass (Centropristis striata), 34 gag (Mycteroperca mircrolepis), 27 greater amberjack (Seriola dumerili), nine almaco jack (S. rivoliana), and eight red snapper (Lutjanus campechanus) on four artificial reef complexes near Cape Lookout, North Carolina, U.S. Available artificial reef structures consisted of materials of various sizes and heights made of concrete and metal. We tracked tagged fish using a fine-scale positioning system for ~100 days. Black sea bass exhibited high site fidelity to the artificial structure where we caught them, rarely moving away from that structure. The limited movement resulted in low transition probabilities; we conclude that black sea bass do not select for particular artificial structures. Gag and red snapper moved greater distances away from artificial structures and routinely moved between them. Greater amberjack and almaco jack moved the most within the complexes displaying circling behavior around individual structures and were the only species that regularly moved off the artificial reef complexes. Greater amberjack movements away from artificial sites were most commonly directed to surrounding shipwrecks. Whereas gag, red snapper, almaco jack, and greater amberjack used all available structures, they consistently selected for high relief structures, such as vessels, more than other structures. These results will be useful to managers charged with decisions on what types of structures to place at artificial reef complexes to supplement or enhance habitat for economically important fishes.

The ecological 'attraction' and 'production' functions of reef areas have been the subject of ongoing debate requiring further clarification. The present study focused on the black rockfish (Sebastes schlegelii), an economically dominant species in reef areas of Dabuquan Bay. Comparisons of stable carbon (C) isotopes between the muscle and liver tissues of black rockfish were conducted to identify residency and potential sources of non-resident individuals in the coastal Yellow Sea, China. Subsequently, isoscape values, derived from C isotopes of zooplankton gathered from inshore and offshore areas surrounding the reef, were compared to determine potential sources of the non-resident black rockfish individuals. According to the results, (1) the isotopic values between the muscle and liver tissues of black rockfish remained consistently aligned across both reef and control areas but showcased significant seasonal variations, and (2) the residency ratios of individuals within the reef area exceeded 84% across all seasons, highlighting the prolonged stays of this species. The findings are consistent with previous studies on rockfish residency and could facilitate the formulation of strategies for local stock enhancement and management. [ABSTRACT FROM AUTHOR]

Plankton are an important component of marine protected areas (MPAs), and its communities would require much smaller interpatch distances to ensure connection among MPAs. According to the survey from MPAs dominated by artificial reefs and adjacent waters (estuary area (EA), aquaculture area (AA), artificial reef area (ARA), natural area (NA) and comprehensive effect area (CEA)) in Haizhou Bay in spring and autumn, we analyzed phyto-zooplankton composition, abundance and biomass, and correlation with hydrologic variables to gain information about the forces that structure the plankton. The results showed that the dominant zooplankton were copepods (spring, 98.9%; autumn, 94.2%), while the phytoplankton were mainly composed of Bacillariophyta (spring, 61.8%; autumn, 95.6%). The RDA results showed that temperature, salinity and depth highly associated with the distribution and composition of plankton species among the habitats than other factors in spring; temperature, Chla and DO had the strongest influence in autumn. The zooplankton in the ARA and AA ecosystems basically contained the same species as those in other habitats, and each habitat also exhibited a relatively unique combination of plankton species. The structures of the EA zooplankton in spring and the EA phytoplankton in both seasons were much different than other habitats, which may have been caused by factors such as currents and tides. We concluded that there exists similarity of the plankton community between artificial reef area and adjacent waters, whereas the EAs may be relatively independent systems. Therefore, these interaction between plankton community should be considered when designing MPA networks, and ocean circulations should be considered more than the environmental factors. [ABSTRACT FROM AUTHOR]

Introduction: Coastal ecosystems, including reefs, are becoming increasingly threatened as anthropogenic development continues to encroach on intertidal habitats with little initiative to establish ecologically considerate infrastructure. Submerging human-made, shelter-providing structures known as artificial reefs (AR) can contribute to the preservation of these ecosystems. ARs are historically used for promoting the abundance and biodiversity of marine species for aquaculture, conservation, and ecotourism; and are typically made of concretes or metal structures. An AR’s success correlates to its ability to establish a surface layer of microorganisms, such as microalgae and bacteria, known as a biofilm. The productivity of the biofilm can be influenced by material surface properties. It is hypothesized that material pH and porosity affect the rate of biofilm formation. Methods: Here - a range of concrete mixtures were cast and submerged in circulating seawater and mass per surface area of biofilm accumulation was measured to evaluate this theory. These mixtures included standard Portland Cement (PC), PC with admixtures of diatomaceous earth (PDC) and limestone (PLC), fine-aggregate high-performance concrete (DUC), and terra cotta (TER). ARs were manufactured as 38mm tall cylinders, 76mm in diameter, and submerged in circulating seawater to evaluate mass per surface area of biofilm accumulation. Results: Our results indicate that biofilm formation is directly affected by surface porosity and less-so by pH, as determined by measuring material properties after submersion. We found that the PDC samples were most successful in forming a biofilm despite being more fragile than other concrete samples. Discussion: This preliminary study provides insight into how different material properties influence the accumulation of biofilm as a starting point for designing ARs. Future work will investigate the long-term performance of such samples in relevant conditions. [ABSTRACT FROM AUTHOR]

The combined release of artificial reefs in different quantities and arrangements leads to different flow field effects. This study designs a small trapezoidal artificial reef. To optimize the quantity and layout of these reefs, trapezoidal reefs in three different layouts were selected for analysis at five different velocity gradients (0.1, 0.5, 1.0, 1.5, and 2.0 m/s). The effects of disposal spacing and layout on the flow field effect of trapezoidal artificial reefs at different flow velocities were simulated using Ansys Fluent. According to the findings: after simulation, flow velocity could indirectly reflect the distribution of upwelling and back eddy, the scale and strength of upwelling increased as flow velocity increased, and the back eddy showed no obvious variation with flow velocity. In transverse combination mode, both the scale and strength of the upwelling and back eddy were maximized when the reef spacing was 1.0 L; in longitudinal combination mode, upwelling and back eddy reached maximum scale and strength when the disposal spacing of the reefs was 1.5 L of a single reef. In 2020, flow mapping and fishery surveys were carried out in the engineering pilot area. The results showed that the number and species of fish populations with 1.5 L spacing in the vertical combination method were significantly higher than those in other forms, and the structure of the fish reef was stable without any flipping or sliding phenomenon. This study can provide a theoretical reference for the design and the actual deployment of artificial reefs to improve the ecological restoration of the water. [ABSTRACT FROM AUTHOR]

Artificial reefs featuring different shapes and functions have been deployed around the world, causing impacts on marine ecosystems. However, the approaches typically used to deliver topological complexity, flexibility and expanding requirements to prospective structures during the initial design stages are not well established. The aim of this study was to highlight the advantages and provide evidence on how modularity and parametric design can holistically leverage the performance of multifunctional artificial reefs (MFARs). In particular, the goal was to develop a parametric design for MFAR and establish a direct relationship between specific design parameters and the MFAR target functions or design requirements. The idea of implementing the parametric design for generating the initial biomimetic geometry of the individual modular unit was explored. Furthermore, possible ways of manipulating the geometric parameters of the individual module and the whole assembly were proposed. The findings suggest that, by adopting the developed procedure and the examples studied, several functions may be reached within a single assembly: the promotion of marine biodiversity restoration, the support of scientific platforms with various sensors, as well as the development of recreational diving and of touristic attraction areas. Acquired knowledge suggests that the concept of a nature-like design approach was developed for artificial reefs with varying scales, complexity and functions, which widens the range of possibilities of how smart design of human-made underwater structures may contribute to benefiting the near shore ecosystems.

In recent years, with the scale and standardization of Stichopus japonicus mariculture, artificial reefs are increasingly used in S. japonicus farming to promote the development of the S. japonicus aquaculture industry. To provide shelter and improve the habitat environment for S. japonicus, three types of artificial reefs (box-shaped reef, triangular-shaped reef, and trapezoidal-shaped reef) were designed according to the ecological habitats of S. japonicus and the marine environment of Haizhou Bay (China) in the present study. After comprehensively comparing the three reef structures, we found that the trapezoidal-shaped reef has good permeability, a larger attachment area, and excellent anti-slip and anti-overturning properties. Further, the flow field characteristics surrounding a trapezoidal-shaped reef at different angles and flow velocities are investigated by three-dimensional numerical simulations. Then, the impact of the placement distance on the flow field surrounding the artificial reef combination was investigated. At the head-on angle θ = 0°, the upwelling volume increases as the flow velocity increases and then decreases, and the back eddy volume remains relatively constant. At the longitudinal spacing D = 4 L, the large slow-flow area surrounding the reef under this condition is more suitable for the S. japonicus habitat. In this study, the trapezoidal-shaped reef design is suitable and beneficial for S. japonicus aquaculture. Moreover, this study will contribute theoretical references to the design and arrangement of artificial reefs in coastal areas.

IntroductionCoastal ecosystems, including reefs, are becoming increasingly threatened as anthropogenic development continues to encroach on intertidal habitats with little initiative to establish ecologically considerate infrastructure. Submerging human-made, shelter-providing structures known as artificial reefs (AR) can contribute to the preservation of these ecosystems. ARs are historically used for promoting the abundance and biodiversity of marine species for aquaculture, conservation, and ecotourism; and are typically made of concretes or metal structures. An AR’s success correlates to its ability to establish a surface layer of microorganisms, such as microalgae and bacteria, known as a biofilm. The productivity of the biofilm can be influenced by material surface properties. It is hypothesized that material pH and porosity affect the rate of biofilm formation.MethodsHere - a range of concrete mixtures were cast and submerged in circulating seawater and mass per surface area of biofilm accumulation was measured to evaluate this theory. These mixtures included standard Portland Cement (PC), PC with admixtures of diatomaceous earth (PDC) and limestone (PLC), fine-aggregate high-performance concrete (DUC), and terra cotta (TER). ARs were manufactured as 38mm tall cylinders, 76mm in diameter, and submerged in circulating seawater to evaluate mass per surface area of biofilm accumulation.ResultsOur results indicate that biofilm formation is directly affected by surface porosity and less-so by pH, as determined by measuring material properties after submersion. We found that the PDC samples were most successful in forming a biofilm despite being more fragile than other concrete samples.DiscussionThis preliminary study provides insight into how different material properties influence the accumulation of biofilm as a starting point for designing ARs. Future work will investigate the long-term performance of such samples in relevant conditions.

In October 1970, the city of Genoa was devastated by a major flood. A few weeks later, hundreds of wrecked cars removed from the city's streets were sunk off the coast of Varazze, in the first-ever Italian project to create an artificial reef. This initiative, which was inspired by similar experiences tried out in the United States and other countries, had been aimed at increasing the fish population and protecting the seabed but was carried out without any thorough preliminary scientific study, and produced other effects not in the initial intentions of the project. Nonetheless, this story should be read as one point in the broadest trajectory in the evolution of environmental discourse. This contribution, based on hitherto unpublished visual documentation, is therefore an investigation into the very specific meaning of the environment in Italy at the beginning of the 70s. The first part of the article provides a reconstruction of the operational details involved in creating the new underwater seascape of Varazze while in the second part, the earlier examples of similar initiatives are described, as well as the reactions of the scientific community. In conclusion, we reflect on the legacy of the initiative, both at the environmental level and as a basic step in the relationship between visual media and contemporary environmental discourse. [ABSTRACT FROM AUTHOR]

With the recent development from grey infrastructures to green infrastructures, artificial reefs become more popular in coastal protection projects. To investigate the responses of beach profile evolution to the presence of an artificial reef, a non-hydrostatic model is established. Both hydrodynamic and morphodynamic evolution for the beach with and without an artificial reef are compared under regular wave conditions. In addition, the protected beach profile evolution by an artificial reef is discussed under irregular wave conditions. Three key parameters in non-hydrostatic simulation are considered for sensitivity analysis, including maximum wave steepness criterium (maxbrsteep), water depth factor (depthscale), and equilibrium sediment concentration factor (sedcal). The numerical results under regular wave conditions indicate that the artificial reef enhances wave attenuation by inducing wave breaking. In addition, the artificial reef reduces local flow velocity and offshore sediment transport by 51%, therefore decrease the total erosion by 53%. Over the artificial reef, wave skewness and asymmetry go through a drastic change. Under irregular wave conditions, short waves contribute to the wave energy mainly and reflection-induced standing wave effects decline considerably. It demonstrates that the artificial reef can protect the beach from regular and irregular waves by reducing erosion and offshore transport of suspended sediments. Moreover, in the wave breaking area, the increase of maximum wave steepness criterium may give arise to the wave height. The morphological evolution is more sensitive to water depth factor than equilibrium sediment concentration factor, because the former is a controlling factor for beach profile characteristics while the latter forms the sandbar varying irregularly in shape. [ABSTRACT FROM AUTHOR]

The fishery resources in the Furong Island, Laizhou Bay artificial reef were investigated in 2019; the energy flows and structure of the ecosystem were modeled, and the ecological capacity of Apostichopus japonicus was estimated using an Ecopath with Ecosim 6.6 (EwE 6.6). The model included 16 functional groups that covered the main processes of energy flows in the Furong Island artificial reef ecosystem. According to the results, the trophic levels of the functional groups varied from 1.000 to 3.978; Lateolabrax maculatus occupied the highest trophic level. The total transfer efficiency was 10.6%, and the proportions of the total flow originating from primary producers and detritus were 10.8% and 10.1%, respectively. The total system throughput was estimated to be 2 596.108 t/(km2·a), with 44% originating from detritus. The ratio between the total primary productivity and the total respiration of the system was 1.454; the connectance index was 0.402; the system omnivory index was 0.211; and the Finn cycling index and Finn mean path length were 8.860% and 2.980, respectively. The results showed that the Furong Island artificial reef ecosystem was at a relatively low maturity and stability level with a relatively simple food web. The ecological capacity of A. japonicus estimated by the model was 131 t/km2, which is 6.55 times the existing stock, indicating its growth potential. According to the actual production situation, the ecological balance of the ecosystem can be maintained with an annual catch of 4.1 t/km2. At present, there are few studies using the Ecopath model to evaluate the ecological consequences or ecological capacities of artificial reefs, in China or abroad, and there is little discussion about fishery management models. More applications and verification on artificial reefs are required. This study is expected to provide a scientific basis for the evaluation of ecological consequences of artificial areas and the sustainable utilization of marine ranches.

The fluctuating asymmetry (FA) of fish otoliths can reflect the difference in the growth and development of fish in sea areas greatly affected by environmental pressure, thus enabling the assessment of different habitats. In this study, using 113 Collichthys lucidus samples collected from different functional areas (estuary area, aquaculture area, artificial reef area and natural area) in Haizhou Bay, the square coefficient of asymmetry variation (CV2a) of four characters (length, width, perimeter and area) of the left and right sagittal otoliths was calculated. The results showed that the CV2a value of otolith width was the lowest and that of otolith length was the highest. The CV2a value had no obvious regularity with increasing fish body length. In addition, the CV2a values of the four characteristics reached their lowest values in the artificial reef area, indicating that the construction of marine ranching dominated by artificial reefs may partly improve the aquatic environment in this functional area. We consider that the otolith FA of C. lucidus can be used as a characteristic of environmental stress between different areas/regions/habitats. [ABSTRACT FROM AUTHOR]

The design of an artificial reef (AR) module for improving the fishing productivity of cephalopod molluscs in the Ares-Betanzos estuary (Galicia, NW Spain) is addressed in this study. At the time of deciding on a suitable AR design, it is first necessary to assess how the different marine species use ARs so that it is possible to define the complexity of the design: its size and shape, as well as the number of nest cavities it should present and the dimensions of these cavities. Thus, two different cubic modules are proposed, both with an edge of 1500 mm. One of them can be considered as the standard design, while the other has been modified to include four open cylindrical holes. Several tools are employed to assess both proposals. Moreover, a CFD (computational fluid dynamics) model is performed. The results suggest that the flow in the interior of the tubes provides a suitable environment for cephalopod molluscs, given that circulation is produced, guaranteeing nutrient renewal. As further contributions, the present work determines how the capture of cephalopods and other species in Galician fish markets has evolved and reviews the habitat preferred by cephalopods in Galicia. It also proposes and compares two AR modules. [ABSTRACT FROM AUTHOR]

Installations of artificial structures in coastal oceans create de facto habitat for marine life. These structures encompass wide varieties of physical characteristics, reflecting their multiple, diverse purposes and creating a need to understand which characteristics maximize fish habitat. Here, we test how physical characteristics – horizontal area, vertical relief, and spatial isolation – relate to fish density from echosounder surveys over artificial structures like concrete pipes, train boxcars, and ships purposely sunk to function as reefs. Echosounder mapping of 31 artificial reef structures and associated fish across a 200 km linear length of the continental shelf of North Carolina, USA, revealed that structures with greater horizontal area and vertical relief host higher fish densities than smaller, shorter structures. Artificial structure spatial arrangement also relates to fish density, as isolated structures are generally associated with greater localized fish densities than structures closer to one another. Patterns in the relationships between fish density and reef characteristics differed for schooling fish, as there was some evidence that reefs of intermediate area exhibited higher schooling fish density. These results suggest that intentional design and spatial arrangement of marine built structures like artificial reefs relates to and can be deliberately incorporated into siting and deployment decisions to enhance their role as fish habitat.

Hard substrates play an important role in global marine systems as settlement surface for sessile reef-forming species such as corals, seaweeds, and shellfish. In soft-sediment systems, natural hard substrates such as stones, bedrock and driftwood are essential as they support diverse assemblages of reef-associated species. However, availability of these hard substrates has been declining in many estuaries and shallow seas worldwide due to human impacts. This is also the case in the Dutch Wadden Sea, where natural hard substrates have gradually disappeared due to burial by sand and/or active removal by humans. In addition, driftwood that was historically imported from rivers has been nullified by upstream logging and coastal damming of estuaries. To investigate the historic ecological role of wood presence in the Wadden Sea as settlement substrate and fish habitat, we constructed three meter high artificial reefs made of felled pear trees. Results demonstrate that these reefs rapidly developed into hotspots of biodiversity. Within six months, the tree-reefs were colonized by sessile hard substrate associated species, with a clear vertical zonation of the settled species. Macroalgae and barnacles were more abundant on the lower parts of the reef, while bryozoans were more dominant on the upper branches. In addition, six fish species were observed on the reefs, while only two species were caught on sandy control sites. Moreover, the abundance of fish on the reefs was five times higher. Individuals of the most commonly caught species, the five-bearded rockling Ciliata mustela, were also larger on the reef. These patterns also hold true for common prawn, Palaemon serratus, which were also larger and ten times more numerous on the reefs. Present findings indicate that the reintroduction of tree-reefs as biodegradable, structurally complex hard substrates can increase local marine biodiversity in soft-sediment systems within relatively short time scales.

The industrial integration of offshore wind power and marine ranches has been actively explored and developed in many countries. This emerging industrial synergy can significantly improve the ecological friendliness of offshore wind power and contribute to the development of the marine economy in the region. This industrial synergy is an important development direction for future offshore engineering. Artificial reefs (ARs) are critical components of marine ranches and are widely placed around offshore wind foundations (OWFs). The ARs can block the water flow and form a complex wake region behind it, which changes the original turbulence structure and reduces scour around the OWF. Therefore, determining the arrangement of ARs for scour protection around an OWF is of great engineering significance. In this study, a three-dimensional numerical model is established using a prototype of the first offshore wind power-marine ranch demonstration project in China. The turbulent change and sediment movement between the OWF and ARs are solved using the Reynolds-averaged Navier-Stokes (RANS) and sediment transport equations. Moreover, the variations in the maximum scour depth and scour volume around the OWF at different arrangements of ARs are explored. The results demonstrate that the arrangement of ARs weakens the horseshoe vortices in front of the OWF and destroys the vortex shedding behind the OWF, thereby producing a beneficial scour protection effect. Various arrangements of ARs have different effects on scour results around the OWF. Increasing the height of the AR could significantly reduce the scour results around the OWF and play an effective role in scour protection, followed by the tandem arrangement of ARs, whereas the parallel arrangement of ARs will produce negative scour effects. This study will serve a vital guiding role in the arrangement of ARs and practical significance for scouring protection around the OWF.

Summer mortality and morbidity are serious environment-related problems in cultured sea cucumbers (Apostichopus japonicus). Air exposure probably worsens the impact of high temperature on cultured sea cucumbers. In this present study, two laboratory experiments were designed to investigate the effects of artificial reefs on mortality, morbidity, crawling, feeding, and adhesion behaviors of small sea cucumbers (~1 g of wet body weight) after air exposure and disease outbreaks at 25 °C, respectively. Significantly lower mortality and morbidity occurred in the group with artificial reefs compared with those in the group without artificial reefs in the two experiments. This present study found that the stressed sea cucumbers cultured inside artificial reefs showed a significantly higher adhesion index, feeding behavior, and crawling frequency than those cultured without artificial reefs. In disease challenge assays, small sea cucumbers cultured inside the artificial reefs showed a significantly higher adhesion index and crawling frequency than those cultured without artificial reefs at 25 °C. Feeding, crawling, and adhesion behaviors of sea cucumbers cultured outside artificial reefs were not significantly different from those cultured without artificial reefs. The experimental results indicate that sea cucumbers with good fitness-related behaviors may be less affected by the disease and more likely to move into the crevices of artificial reefs. Fitness-related behaviors were poor in sea cucumbers cultured outside artificial reefs, so we considered them as affected individuals. Thus, artificial reefs provide a place to reduce the physical contact between unaffected and diseased/affected individuals, showing a potential to reduce disease transmission. Our present study establishes a cost-effective approach to increasing the survival of small sea cucumbers in seed production at high temperatures. [ABSTRACT FROM AUTHOR]

To explore the ecological effects of artificial reef (AR), multidimensional evaluations involving density, biodiversity and spatial heterogeneity of nekton community were studied in Beibu Gulf China. The spatial pattern of nekton community was clearly classified into two groups (A and B) in April 2017. However, the variation of nekton densities between A (48529 ind/km2) and B (30220 ind/km2) was not significant (P= 0.17). Therefore, the ecological effects evaluation of AR merely based on density assessment is not sensitive enough. Shannon-Wiener diversity (H') and Pielou evenness (J') in group A (2.74 and 0.78) were significantly higher than that in group B (2.3 and 0.7), implying an obvious ecological restoration effect of AR. Furthermore, crustaceans such as Alpheus brevicristatus, Charybdis callianassa and Harpiosquilla harpax, showing a distinct preference tropism to AR, were turned out to be the main factors contributing to the spatial heterogenity of nekton community between A and B, which was closely related to dissolved oxygen (DO), water transparency (Tra) and total inorganic nitrogen (TIN). The findings in this paper are significant for the protection and restoration of crustaceans resourcs along coastal water, given the rapid establish of AR around the world. [ABSTRACT FROM AUTHOR]

Coral reefs are three-dimensional biogenic structures that provide habitat for plenty of marine organisms; yet, coral reefs are deteriorating worldwide. Hence, it is essential to identify suitable substitutes for such coral services. This study examines reef fishes' behavior and reactions to three-dimensional-printed (3DP) corals based on scanned Stylophora pistillata, as well as modified 3DP models. In particular, fishes' unresponsiveness to the color, shape, morphology, and material of 3DP models both in vitro and in situ experiments was investigated. Coral reef fishes responded to the 3DP corals and demonstrated their usage in a range of services. Moreover, a greater number of fish species interacted more with 3DP models than they did with live corals. Furthermore, specific reef fish species, such as Sea Goldies (Pseudanthias squamipinnis), showed a preference for specific 3DP coral color, and other species demonstrated preferences for specific 3DP model shapes. The current study results show that three-dimensional-printed coral models can substitute for live corals for certain types of reef fish services. [ABSTRACT FROM AUTHOR]

By means of literature review and field investigation in the sea area, the development and current situation of marine ranching at home and abroad are summarized, and the construction process of artificial fish reefs, proliferation and releasing and national marine ranching demonstration areas in Guangdong as well as the development status and existing problems of marine ranching related industries are analyzed. Guangdong has built 50 ecological artificial reef areas, 3 largescale artificial reef demonstration areas, 1 local artificial reef area and 15 national marine ranching areas, with a total sea area of 1 499.68 km2, and 2.004 million m3 of reefs being built. However, at present, there are some problems in Guangdong marine ranching, such as imperfect management mechanism, inconsistence in development concept and understanding, unclear rights and responsibilities in using sea area, lack of construction technology standards and specifications, low scientific and technological level and limited industrial development. Based on these problems, countermeasures for the development of marine ranching in Guangdong Province are put forward: insisting on ecology-prioritized development, and strengthening the coordination of multiple departments; creating a management mode conducive to market-oriented operation; break through the issue of sea area ownership; establishing a technical standard system for marine ranch construction in Guangdong; increasing the research on the basis of high-quality construction and key common technologies of Guangdong marine ranching; establishing industrialization modes of Guangdong m arine ranching according to local conditions. Understanding the development status of marine ranching in Guangdong and exploring the development strategies of marine ranching industry by referring to the relevant experience at home and abroad can provide references for the effective management, efficient and sustainable development of marine ranching in Guangdong and the integration of three industries in the development of marine ranching in Guangdong.