Artificial Reefs Research Articles

Creating wildlife habitat using artificial structures: a review of their efficacy and potential use in solar farms.

The biodiversity crisis is exacerbated by a growing human population modifying nearly three-quarters of the Earth's land surface area for anthropogenic uses. Habitat loss and modification represent the largest threat to biodiversity and finding ways to offset species decline has been a significant undertaking for conservation. Landscape planning and conservation strategies can enhance habitat suitability for biodiversity in human-modified landscapes. Artificial habitat structures such as artificial reefs, nest boxes, chainsaw hollows, artificial burrows, and artificial hibernacula have all been successfully implemented to improve species survival in human-modified and fragmented landscapes. As the global shift towards renewable energy sources continues to rise, the development of photovoltaic systems is growing exponentially. Large-scale renewable projects, such as photovoltaic solar farms have large space requirements and thus have the potential to displace local wildlife. We discuss the feasibility of 'conservoltaic systems' - photovoltaic systems that incorporate elements tailored specifically to enhance wildlife habitat suitability and species conservation. Artificial habitat structures can potentially lessen the impacts of industrial development (e.g., photovoltaic solar farms) through strategic landscape planning and an understanding of local biodiversity requirements to facilitate recolonization.

Red snapper excavate sediments around artificial reefs: observations of ecosystem-engineering behavior by a widely distributed lutjanid

Hard substrate and vertical relief are limited habitat resources for reef-associated species in many regions. On the West Florida Shelf (WFS) of the Gulf of Mexico, red grouper Epinephelus morio act as ecosystem engineers by excavating sediments to expose limestone bedrock. Excavations can exceed 25 m in diameter and 2 m in depth and are among the most abundant WFS seafloor features at depths between 40 and 110 m. As part of a survey of hard-bottom habitats and associated reef fish assemblages, 1203 excavations were identified in WFS waters along the Florida Panhandle between 2014 and 2019. These excavations often contained subsided artificial reef material within their interior and infrequently included E. morio among observed fishes. We video-identified red snapper Lutjanus campechanus excavating sediments around 2 subsided artificial reefs in 2015 and 2017 for a total of approximately 56 min of excavation activity. A total of 24 excavation events were documented around a tire pile in 2015, and 5 were documented around a pyramid-shaped reef module in 2017. These observations help to explain the subsidence of artificial reefs and apparent excavation around their bases despite the scarcity of previously known excavating species. This suggests that L. campechanus might be ecosystem engineers on the WFS.

Assessing the Conservation Value of Artificial and Natural Reefs via Ichthyoplankton Spatio-Temporal Dynamics

Assessing the Conservation Value of Artificial and Natural Reefs via Ichthyoplankton Spatio-Temporal Dynamics

Community science informs movement and reproductive ecology of sand tigers Carcharias taurus off North Carolina, United States of America

Sand tigers are frequently observed at shipwrecks and other artificial reef habitats off North Carolina (USA), but data about occupancy, movement ecology, and site fidelity are lacking. Spot A Shark USA researchers used Wildbook© photoidentification software to spot map sand tigers in images provided by recreational SCUBA divers, or collected from remotely operated vehicles, and an offshore live-streaming camera. We uniquely identified 1837 sand tigers, 101 of which were resighted on more than one date between 2005–2021. Sand tigers of both sexes and various ages were found year-round along the northern, central and southern coast. We identified shipwrecks or artificial reef sites with consistently high numbers of shark encounters reported, sometimes with seasonal occupancy patterns. Resighted sharks were often encountered at the same or nearby locations, confirming high levels of residency and site fidelity to specific locations. Together, the mating scars seen on 121 female sand tigers and 202 females documented with rotund abdomens consistent with pregnancy highlight the importance of NC waters for reproduction. We also quantified other characteristics of the sand tigers visible in the photographs including wounds, parasitic copepods, and attached fishing gear. Our results reflect the importance of habitats off the NC coast to the movement and reproductive ecology of sand tigers at multiple life history stages. Sand tiger populations have declined in the Northwest Atlantic, so information about residence at specific locations, seasonal patterns of occupancy, and sex-dependent behaviors associated with migration and reproduction are important to future management and conservation of the species.

Response of sediment microbial communities to the flow effect of the Triangular Artificial Reef: A simulation-based experimental study

Artificial reefs (ARs), as an important tool for habitat restoration, play significant impacts on benthic microbial ecosystems. This study utilized 16S rRNA gene sequencing technology and computational fluid dynamics (CFD) flow simulation to investigate the effects of flow field distribution around ARs on microbial community structure. The results revealed distinct regional distribution patterns of microbial communities affected by different hydrodynamic conditions. Flow velocity and flow regime of water in sediment-water interface shaped the microbial community structure. The diversity and richness in R-HF were significantly decreased compared to other five regions (p<0.05). At the phyla and OUT levels, most abundant taxa (1>%) showed an enrichment trend in R-HB. However, more than half of differentially abundant taxa were enriched in R-HB, which was significantly correlated with organic matter (OM). Bugbase phenotypic predictions indicated a low abundance of the anaerobic phenotype in R-HF and a high abundance of the biofilm-forming phenotype in R-HB.

Optimizing Infragravity Wave Attenuation to Improve Coral Reef Restoration Design for Coastal Defense

Coral reefs are effective natural flood barriers that protect adjacent coastal communities. As the need to adapt to rising sea levels, storms, and environmental changes increases, reef restoration may be one of the best tools available to mitigate coastal flooding along tropical coastlines, now and in the future. Reefs act as a barrier to incoming short-wave energy but can amplify low-frequency infragravity waves that, in turn, drive coastal flooding along low-lying tropical coastlines. Here, we investigate whether the spacing of reef restoration elements can be optimized to maximize infragravity wave energy dissipation while minimizing the number of elements—a key factor in the cost of a restoration project. With this goal, we model the hydrodynamics of infragravity wave dissipation over a coral restoration or artificial reef, represented by a canopy of idealized hemispherical roughness elements, using a three-dimensional Navier–Stokes equations solver (OpenFOAM). The results demonstrate that denser canopies of restoration elements produce greater wave dissipation under larger waves with longer periods. Wave dissipation is also frequency-dependent: dense canopies remove wave energy at the predominant wave frequency, whereas sparse canopies remove energy at higher frequencies, and hence are less efficient. We also identify an inflection point in the canopy density–energy dissipation curve that balances optimal energy losses with a minimum number of canopy elements. Through this work, we show that there are an ideal number of restoration elements per across-shore meter of coral reef flat that can be installed to dissipate infragravity wave energy for given incident heights and periods. These results have implications for designing coral reef restoration projects on reef flats that are effective both from a coastal defense and costing standpoint.

The ecological risk and fate of microplastics in the environmental matrices of marine ranching area in coastal water

The debate surrounding "source" and "sink" of microplastics (MPs) in coastal water has persisted for decades. While the transportation of MPs is influenced by surface runoff and currents, the precise transport patterns remain inadequately defined. In this study, the typical coastal habitat – marine ranching in Haizhou Bay (Jiangsu Province, China) were selected as a case study to assess the ecological risk of MPs. An enhanced framework was employed to assess the entire community characteristics of MPs in various environmental compartments, including surface water (SW), middle water (MW), bottom water (BW), sea bottom sediment (SS), and intertidal sediment (IS). The results of the assessment showed a low risk in the water column and a high risk in the sediment. PERMANOVA based on size and polymer of MPs revealed significant differences between IS and other compartments (SW, MW, BW, and SS) (P<0.001). The co–occurrence network analysis for MP size indicated that most sites occupied central positions, while the analysis for MP polymer suggested that sites near the marine ranching area held more central positions, with sites in MW, BW, and SS being somewhat related to IS. Generalized additive model (GAM) demonstrated that MP concentration in the water correlated with Chla and nutrients, whereas MPs in sediment exhibited greater susceptibility to dissolved oxygen (DO) and salinity. We believe that except for the natural sedimentation and re–suspension of MPs in the vertical direction, MPs in bottom water may migrate to the surface water due to upwelling mediated by artificial reefs. Additionally, under the combined influence of surface runoff, currents, and tides, MPs may migrate horizontally, primarily occurring between middle and bottom water and sediments. The study recommends limiting and reducing wastewater and sewage discharge, as well as regulating fishing and aquaculture activities to control the sources and sinks of MPs in coastal water. Moreover, it advocates the implementation and strengthening of marine monitoring activities to gain a better understanding of the factors driving MP pollution in marine ranching area.

Haven or hell? A perspective on the ecology of offshore oil and gas platforms

Offshore oil and gas platforms (OGP) have been installed worldwide and initially with limited consideration given to the nature of their positive or negative long-term interactions with the natural marine habitats. However, as OGP reach the end of their useful life, with many being decommissioned and removed, it is timely to review the growing evidence of the association of marine biota with OGP to provide a summary and synthesis for policy makers and to give insight to decisions in increasingly crowded marine spatial plans. In the last decade, there has been rapid increase in studies concerning the ecological role of OGP. This research reveals strong contextual difference between platforms in different geographical regions, but all OGP add to local biodiversity particularly where hard substrata are introduced to areas dominated by depositional (mud and sand) habitats. This includes the attraction and increased productivity of fish, sessile invertebrates, and algae while also affecting change in the benthic habitats beneath platforms. There also evidence of the OGP changing local hydrodynamics conditions with effects on phytoplankton and local scour. In terms of the biota associated with OGP, water depth is a major driver of community type across systems. This study emphasises that while knowledge of OGP communities and species has improved, there are still significant knowledge gaps that may prevent the most environmentally beneficial decisions being made around decommissioning. There are few studies following the effect of decommissioning (topping, toppling, or removal) on the ecology of the systems as they change with time (longitudinal research) for the decommissioning event. There is also a need for more studies comparing the biodiversity and functionality of OGP system to artificial and natural reefs and habitats to better understand the ecological cost-benefit of decommissioning scenarios. Finally, commercial data is often unavailable and even when available, surveys are often conducted using varied methodology that prevents comparative analysis. By imposing/agreeing standards and sharing data around the ecological cost-benefit of decommissioning strategies, improve policy guidance concerning OGP planning, and management might emerge.

Artificial structure selection by economically important reef fishes at North Carolina artificial reefs

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.

Evaluating climate change impacts on reef environments via multibeam echosounder and Acoustic Doppler Current profiler technology

Crucial to the Earth's oceans, ocean currents dynamically react to various factors, including rotation, wind patterns, temperature fluctuations, alterations in salinity and the gravitational pull of the moon. Climate change impacts coastal ecosystems, emphasizing the need for understanding these currents. This study explores multibeam echosounder (MBES), specifically R2-Sonic 2020 instrument, offering detailed seabed information. Investigating coral reefs, rocky reefs and artificial reefs aimed to map seafloor currents movement and their climate change responses. MBES data viz. Bathymetry and backscatter were classified and acoustic doppler current profiler (ADCP) ground data were validated using random forest regression. Results indicated high precision in currents speed measurement i.e. coral reefs with 0.96, artificial reefs with 0.94 and rocky reefs with 0.97. Currents direction accuracy was notable in coral reefs with 0.85, slightly lower in rocky reefs with 0.72 and artificial reefs with 0.60. Random forest identified sediment and backscatter as key for speed prediction while direction relies on bathymetry, slope and aspect. The study emphasizes integrating sediment size, backscatter, bathymetry and ADCP data for seafloor current analysis. This multibeam data on sediments and currents support better marine spatial planning and determine biodiversity patterns planning in the reef area.

Coastal Ecological Connectivity between Seagrass Bed and Marine Ranching 30 km Apart: A Case STUDY of Apostichopus japonicus Feeding on Seagrass Debris in the Bohai Sea, China

Coastal ecosystems form interconnected networks that are essential for the maintenance of marine biodiversity. This study investigates the dietary patterns of Apostichopus japonicus (sea cucumber) within a marine ranching ecosystem and reveals the influence of Zostera marina (seagrass) leaves from a distant bed on nutrient availability and trophic connectivity. Samples collected between September 2020 and March 2021 from Xiangyun Bay included A. japonicus, macroalgae, phytoplankton, and seagrass leaves. Stable isotope analysis (δ13C and δ15N), in conjunction with Bayesian mixing models, elucidated the contributions of different food sources to A. japonicus’ diet. Macroalgae constituted more than 50% of A. japonicus’ diet, while seagrass contributions ranged between 5.7% and 11.3%. The isotopic analysis confirmed the presence of seagrass debris in the marine ranching environment, indicating significant nutrient transport from a remote seagrass bed. This study underscores the crucial role played by macroalgae as the primary source of nutrients for A. japonicus within a marine ranching setting. Furthermore, detecting seagrass debris from a distant habitat highlights previously unrecognized ecological connectivity between seagrass ecosystems and artificial reef environments along coastal areas. This understanding of long-range nutrient transfers is vital for effective management and conservation strategies in coastal marine systems, emphasizing intricate yet significant ecological interdependencies across coastal environments.

Flow Field Characteristics of Multi-Trophic Artificial Reef Based on Computation Fluid Dynamics

Flow Field Characteristics of Multi-Trophic Artificial Reef Based on Computation Fluid Dynamics

Use Crumb Rubber Chips in Partial Substitution of Coarse Aggregate While Preparing Concrete

Abstract: The purpose of this experimental investigation is to examine the behaviour features of rubberized concrete, which has coarse aggregate in place of some of the tyre rubber. Over 270 million scrap tyres are thought to be produced annually. One of the main problems in India is the disposal of discarded tyres in landfills, which is the responsibility of local governments and municipalities. Because it is not biodegradable, there are serious concerns to human health, the environment, and fire. The most promising uses of tyres in engineering are as aggregates for asphalt and concrete, artificial reefs, and erosion management, aside from gasoline obtained from tyres. Concrete's characteristics could be greatly improved in a variety of ways by using recycled tyre rubber as part of the aggregate. One of the most often used building materials is concrete. Because of this, the building sector is constantly looking for new applications and uses for its products, as well as ways to improve them while keeping costs down. The reference concrete specimen is made of M30 grade concrete. Rubber chips from scrap tyres have been utilised in place of traditional coarse aggregate as coarse aggregate. This will enable the efficient and widespread handling of rubber tyre waste in addition to enabling the sustainable use of the aggregates that are already accessible to us. After separating the rubber tyre waste into coarse chips, this tyre crumb aggregate is applied in increments of 5%, 10%, or 15% to replace the coarse aggregate. In order to determine the best way to employ crumb rubber as coarse aggregate in concrete, this study assessed the workability and compressive strength of rubberized concrete

The Coral Chronicles: Climate Crisis and Its Implications on the Global Coral Reefs

The coral reefs are one of the most devastating causalities that is often overlooked as our planet grapples with the continually progressing crisis of climate change. They are often addressed as the rainforests of the sea and are hubs of biodiversity that support a one-fourth of all marine species even though they only cover less than one percent of the ocean floor. Not only are they inhabiting countless marine creatures, they are also a crucial food an income source to the millions of people worldwide. Alas! These vibrant underwater ecosystems are being pushed to the brink of collapse due the relentless onslaught of climate change. &#x0D; Consider the Great Barrier Reef, off the coast of Australia, where extensive coral bleaching events are occurring due to rising sea temperatures [1]. The threat of ocean acidification has jeopardized the coral reef in the Maldives and is potentially affecting the country economically which is based on the tourism and fisheries. Likewise, Caribbean Sea is facing disease outbreak and coral bleaching. Philippines is home to some of the most diverse coral reefs in the world but, climate change, overfishing and coastal development is threatening these natural ecosystems. Apart from these, Seychelles and Mauritius in the Indian Ocean and the Coral triangle in the Southeast Asian region are also at stake due to these environmental stressors [2].  &#x0D; In the face of these challenges, many governments, NGOs and local communities have united to conserve these global reefs. Different Marine Protected Areas (MPAs) have been developed to mitigate overfishing and habitat destruction and protect the coral reefs [3]. Moreover, many techniques have been developed to restore the degraded coral ecosystems and enhance their resilience, including Coral Transplantation and Artificial Reef Structures. These initiatives have created the hope that the vibrant coral reefs will eventually recover in face of the existing environmental crises.  &#x0D; However, we cannot overstate that the current situation is dire and nothing short of a global calamity. It is our moral obligation that we protect and preserve these natural wonders for future generations.  If we do not take immediate action to curb the emission of greenhouse gases and fight against the climate change, we risk losing these underwater ecosystems right in front of our eyes. It is our choice and the stakes could not be higher. &#x0D;  

Pre-study of the evaluation of ecological sessile succession and their relationship with bacteria on concrete artificial reef material

Artificial reefs are human-made structures built for promoting marine life. Long-term monitoring and research regarding the use of artificial reefs in terms of ecological and economic perspective is essential. In this study, the ecological succession and their relationship with bacteria on concrete artificial reef material was investigated. Heybeliada artificial reef site was selected as sampling area. After three years period, the visual examination of ecological succession and sessile marine bacteria count were performed on the concrete artificial reef material. All the results showed that the strength of the artificial reef material is also affected by the biofilm layer and the creatures in the microecosystem. Therefore, monitoring studies should be carried out to determine the service life of artificial reef materials as well as to reveal the existence of the ecosystem formed and developing in these areas qualitatively and quantitatively.

Corrigendum to “Pre-study of the evaluation of ecological sessile succession and their relationship with bacteria on concrete artificial reef material” [International Journal of Environment and Geoinformatics 11(1), 30-35 (2024)]

There was a need to correct the errors in chemical oceanography in the findings of Gül and Ünsal's (2024) study, which was about the ecological succession on the concrete artificial reef material in the Heybeliada artificial reef area and its relationship with bacteria.

A global meta-analysis of ecological effects from offshore marine artificial structures

Marine artificial structures (MAS), including oil and gas installations (O&G) and offshore wind farms (OWFs), have a finite operational period. Selecting the most suitable decommissioning options when reaching end-of-life remains a challenge, in part because their effects are still largely undetermined. Whether decommissioned structures could act (sensu ‘function’) as artificial reefs (ARs) and provide desired ecological benefits is of particular interest. Here we use a meta-analysis approach of 531 effect sizes from 109 articles to assess the ecological effects of MAS, comparing O&G and OWFs to shipwrecks and ARs, with a view to inform their decommissioning. This synthesis demonstrates that while MAS can bring ecological benefits, important idiosyncrasies exist, with differences emerging between MAS types, habitat types, taxa and ecological metrics. Notably, we find limited conclusive evidence that O&G and OWFs would provide significant ecological benefits if decommissioned as ARs. We conclude that decommissioning options aimed at repurposing MAS into ARs may not provide the intended benefits.

Signal Photon Extraction and Classification for ICESat-2 Photon-Counting Lidar in Coastal Areas

The highly accurate data of topography and bathymetry are fundamental to ecological studies and policy decisions for coastal zones. Currently, the automatic extraction and classification of signal photons in coastal zones is a challenging problem, especially the surface type classification without auxiliary data. The lack of classification information limits large-scale bathymetric applications of ICESat-2 (Ice, Cloud, and Land Elevation Satellite-2). In this study, we propose a photon extraction–classification method to process geolocated photons in coastal areas from the ICESat-2 ATL03 product. The basic idea is to extract the signal photons using an adaptive photon clustering algorithm, and the extracted signal photons are classified based on the accumulated histogram and triangular grid. We also generate the bottom profile using the weighted interpolation. In four typical coastal areas (artificial coast, natural coast, island, and reefs), the extraction accuracy of a signal photons exceeds 0.90, and the Kappa coefficients of four surface types exceed 0.75. This method independently extracts and classifies signal photons without relying on auxiliary data, which can greatly improve the efficiency of obtaining bathymetric points in all kinds of coastal areas and provide technical support for other coastal studies using ICESat-2 data.

Effect of coral‐giant clam artificial reef on coral recruitment: insights for restoration and conservation efforts

Coral recruitment is a vital process for the maintenance and recovery of coral reefs, particularly due to their decline from global change. While it is well established that larval settlement cues significantly influence coral recruitment, the investigation of recruitment success associated with the surrounding community mainly focuses on algae. To investigate other factors controlling this process, we examined the impact of benthic invertebrate assemblages on coral recruitment using artificial reefs. Three types of artificial reefs (mono‐, bi‐, and tri‐species) with different assemblages of three common species, Pocillopora acuta, Acropora cytherea, and Tridacna maxima, were studied over 8 months. This study revealed that benthic assemblages play a significant role in coral recruitment and survival. High biodiversity was found to enhance coral recruitment and inhibit potential negative cues from A. cytherea. Our findings underscore the importance of preserving high biodiversity using not only hard coral but a wide range of phyla, including bivalves, in coral restoration efforts. Maintaining sustainable populations is an important goal to reach in the face of the multiple threats that impact coral reefs.

Accumulation characteristics and ecological risk evaluation of microplastics in sediment cores from the artificial reef area and surrounding seas of Haizhou Bay, north China

One significant “sink” for microplastic (MP) pollution is the sediments. There's a considerable lack of reliable data regarding the historical status of MPs contamination in sediments within marine ranching. In this research, the study area encompassed Haizhou bay marine ranching and adjacent seas. The primary objective was to explore the potential relationships between the accumulation of MPs and both the sample depth and sediment characteristics within the cores. The results unveiled significant contamination of MPs within the sediment cores. The average MPs concentration of sediment was 1.01 ± 1.28 n/g. Fibrous polymers and particles smaller than 1000 μm were frequently found in the sediment. The abundance of MPs exhibited a tendency to decrease with an increase in sediment depth. Artificial reefs and currents affected on MPs distribution in sediment cores. The accumulation of MPs showed a significant correlation (P < 0.05) with the sediment content of different particle sizes, suggesting that the composition of sediment can serve as an indicator of the abundance of MPs. The risk of MP pollution in the sediments of the study area was assessed by establishing a risk assessment model using concentration data of MPs and polymer types. Due to the higher hazard score of polymers (PA and PET) in MPs, the Polymer hazard index (PHI) was elevated to grade II. However, it had a Pollution load index (PLIzone) value of 1.95 (level I). This suggested that contamination was minimal, yet the ecological risk remained relatively high. The ecological risk assessment of MPs served as the foundation for gaining a detailed understanding of the distribution characteristics of MPs. It also furnished essential data support for conducting a comprehensive assessment, developing feasible management strategies, and establishing water quality standards related to plastic waste.