Deployment Of Artificial Reefs Research Articles

Effectiveness of artificial reefs in enhancing phytoplankton community dynamics: A meta-analysis

Artificial reefs (ARs) are widespread globally and play a positive role in enhancing fish communities and restoring habitat. However, the effect of ARs on phytoplankton, which are fundamental to the marine food chain, remains inconclusive. Conducting a literature review and meta-analysis, this study investigates how ARs influence phytoplankton community dynamics by comparing the biomass, density, and diversity of phytoplankton between ARs and natural water bodies across varying deployment durations, constituent materials, and climatic zones. The study findings suggest that, overall, ARs enhance the biomass, density, and diversity of phytoplankton communities, with no significant differences observed compared to natural water bodies. The enhancement effect of ARs on phytoplankton communities becomes progressively more pronounced with increasing deployment time, with the overall status of phytoplankton communities being optimal when artificial reefs are deployed for 5 years or longer. Concrete and stone ARs can significantly enhance the biomass and diversity of phytoplankton, respectively. The effect of ARs on phytoplankton diversity is unrelated to climatic zones. However, deploying ARs in temperate waters significantly enhances phytoplankton biomass, while in tropical waters, it significantly reduces phytoplankton density. The research findings provide practical implications for the formulation of artificial reef construction strategies tailored to the characteristics of different aquatic ecosystems, emphasizing the need for long-term deployment and appropriate material selection. This study offers a theoretical basis for optimizing AR design and deployment to achieve maximum ecological benefits.

Catalyzing Conservation: An Analysis of Fish Stock Dynamics in a Marine Protected Area before and after Artificial Reef Deployment

The marine ecosystem’s balance is crucial for sustaining biodiversity and supporting fisheries. Marine protected areas have been increasingly used to enhance marine habitats, yet their impact on fish populations remains a topic of debate. This study focuses on a marine protected area in Kitros, Pieria, in Greece, where an artificial reef was constructed, to understand its influence on coastal fish populations. The objectives were to investigate the changes in fish biomass and abundance, comparing the data from periods before and after the construction of an artificial reef. This research compares the data between 2007 and 2008 with the data between 2016 and 2017, collected with bottom trawl surveys strategically executed prior to and after the artificial reef’s installation. Fish species captured were identified, with their lengths and masses measured. The findings indicate an increase in the biomass and abundance of certain fish species after artificial reef deployment, notably the commercially significant Mullus barbatus and Pagellus erythrinus. The artificial reef in Kitros, Pieria, with its surrounding marine protected area appears to have had a positive impact on the local fish populations over the years, suggesting that it can contribute to marine conservation and fishery enhancement. These results underscore the potential of artificial reefs as tools for marine ecosystem management, offering insights for policymakers and environmentalists into coastal resource management.

Artificial Reef Deployment Reduces Diving Pressure from Natural Reefs—The Case of Introductory Dives in Eilat, Red Sea

Artificial reefs have been suggested as alternative dive sites to mitigate human pressure on natural reefs. Despite the conceptual appeal of artificial reefs, there is a paucity of empirical evidence regarding their effectiveness in achieving this objective. Here, we report that a small artificial reef deployed adjacent to a local coral marine protected area caused a shift in the routes taken by introductory dives and nearly eliminated their visitations to the natural fringing reef within the MPA. This behavioral shift among divers persisted for more than a decade following the AR deployment. These findings underscore the efficacy of well-designed and appropriately located artificial reefs as valuable instruments in the conservation of coral reefs.

Shoreline change model after artificial reefs deployment in Tlangoh, Bangkalan, Madura

Fifteen hexagonal artificial reefs were placed on Tlangoh Beach, Bangkalan, Madura Island, in 2022. The reefs have been planned to reduce shoreline erosion that has been occurring in this location since 2020. Pertamina Hulu Energy – West Madura Offshore (PHE – WMO) will deploy more artificial reefs in their CSR (company social responsibility) program. The effect of the artificial reefs on reducing shoreline erosion was usually observed by the change of morphology and shoreline in the study area. The study of shoreline change has gained significant attention due to its substantial impact on coastal environments. Understanding the dynamics of shoreline alteration is crucial for managing and planning coastal development and preserving coastal ecosystems such as artificial reef deployment. Scientists and researchers have developed a generalized shoreline change model called GENESIS to aid in this understanding. This software provides a valuable tool for predicting and analysing coastal erosion and accretion patterns. This paper discusses the shoreline change model in Tlangoh Beach, Bangkalan Madura, after deploying artificial reefs using GENESIS software. The model shows that the length of the artificial reef layout influences the developed shoreline. The longer the reef placement, the more sediment accumulates in the study area

A Numerical Simulation Study and Effectiveness Evaluation on the Flow Field Effect of Trapezoidal Artificial Reefs in Different Layouts

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.

Can Coral Reef Restoration Programmes Facilitate Changes in Environmental Attitudes? A Case Study on a Rural Fisher Community in North Bali, Indonesia

There is currently limited research assessing the ecological potential of coral restoration programmes of habitat enhancement and restoration of benthic and mobile populations for influencing the attitudes (and subsequent behaviours) of the communities where they are based. Our qualitative study investigated the impact of a coral reef restoration programmes on local environmental attitudes in a rural fishing community in north Bali, Indonesia. We conducted semi-structured interviews with individuals and multi-stakeholder focus groups (n = 31) in Tianyar Village, where the NGO ‘North Bali Reef Conservation’ (‘Yowana Bhakti Segara’) was based. Our results highlight several factors that influenced environmental behaviours, including perceived value of coral reefs (e.g.,changes in fishing yield), drivers of support for coral reef restoration (e.g., local leaders’ influence) and barriers to coral reef restoration support (e.g., lack of investment). Overall, our data indicate that the restoration programme has influenced positive environmental attitudes within the community through improvements in waste management, increased support for restoration work, and the establishment of new environmental regulations. Based on our results, we make five recommendations: (1) continuing environmental education within the community, (2) strengthening regulations and improving enforcement, (3) increasing financial and logistical support for waste management and ecotourism, (4) continuing the construction and deployment of artificial reefs, ensuring ‘best practice’ recommendations are followed, and (5) utilising the influence of local leaders to create positive environmental behaviours.

Make a difference: Choose artificial reefs over natural reefs to compensate for the environmental impacts of dive tourism

In the marine environment, natural reef habitats are amongst the most threatened by human activities. Although reef-based ecotourism can benefit local economies, dive tourism can damage sensitive habitats. One solution to managing conflicts between the economic value of diving and its ecological threats is the deployment of artificial reefs near popular dive sites. We surveyed recreational divers to assess divers' use, preference, and perceptions of diving artificial versus natural sites. We found that more divers prefer to dive in natural than artificial habitats, with associated biodiversity the most popular reason for preferring natural habitats, and appreciating shipwrecks the most popular reason for preferring artificial ones. Despite our sample population being highly educated and experienced, predominantly European divers, only 49 % of them perceived artificial reefs as important or somewhat important for diverting pressure from sensitive natural habitats. Similarly, only 13 % of respondents exhibited preference to avoid coral reefs to protect them. These results highlight the fact that more needs to be done to educate divers about the potential importance of artificial habitats in diverting divers from natural reefs. We suggest encouraging divers to switch out a proportion of their dives in vulnerable natural sites for artificial reefs. This is not only true for coral reefs, but should be applied to other natural reef habitats that are popular with divers such as kelp forests, sponge gardens and serpulid and coralligenous reefs. We hope that this study will provide a platform to stimulate a diver-led discussion and campaign for increased uptake of artificial reef use, resulting in reduced impacts on natural reefs.

Structural and functional changes in Artificial Reefs ecosystem stressed by trophic modelling approach: Case study in the Bay of Biscay

Artificial Reefs (ARs) are commonly cited as a tool used for increasing fishery production and reinstating ecosystem functionalities. The assessment of ARs deployment is mostly based on analysis of the evolution of fish communities. Recently, studies have focused on trophic modelling to understand the functioning of such ecosystems in a more holistic approach. Trophic models are able to address this concern by describing the interaction between species at different trophic levels and based on the quantification of energy and matter flows through ecosystems. These models allow the application of numerical methods – also called Ecological Network Analysis (ENA) – to characterize emergent properties of the ecosystem. Usually, ENA indices are proposed as indicators of ecosystem health as they are sensitive to different impacts on marine ecosystems. In the present study, the Ecopath software is used to build an ecosystem model composed of 23 compartments, from detritus and phytoplankton to mammals, to describe the situation “before” and “after” the deployment of ARs in the south of the Bay of Biscay along the Landes coast. In addition, ENA indices are calculated for two periods, “before” and “after” the deployment of artificial reefs, to compare network functioning and the overall properties of the structural trophic network. Our results show little structural change in the ecosystem, with a rearrangement of the trophic levels and a simultaneous increase in biomass and system maturity. These preliminary results evidently need to be confronted with other environmental factors such as, for instance, substrate composition, proximity to natural reefs and larval supply. Nonetheless, we consider that the maturity index could be used as a new indicator to assess the evolution of ARs with specific management objectives.

Effects of artificial reef and fishing moratorium on trophic structure of biological community in the Pearl River Estuary marine ranch based on stable isotopes

Deployment of artificial reefs (ARs) has become popular technique to create new hard-bottom habitats, increase biodiversity and richness for fisheries. We compared the faunal community structure and food web structure associated with before and after fishing moratorium between ARs and non-ARs in Wanshan Island, Pearl River Estuary using stable isotope techniques. Community composition showed higher differences between ARs and non-ARs. The range of δ13C and δ15N of different functional groups can distinguish the pelagic and benthic trophic pathways of the food web in reef-or-not area before and after fishing moratorium. The isotopic niches of entire faunal, as well as individual functional groups, overlapped less between ARs and non-ARs in Wanshan Island, which makes the isotopic functional indices non-equivalent. The total convex hull area (TA) of ARs was larger than that of non-ARs, indicating that nutrient pathways of ARs were more diverse. Overall, however, these results suggest that trophic structure was convergence between ARs and non-ARs, and differences before and after fishing moratorium, possibly due to seasonal differences. Finally, it was shown that the construction of ARs had a weak effect on the restoration of fishery resources in this area, which might be related to lack of further management, or even similar community composition to non-ARs areas.

Distribution of Diatom Resting Stages in Sediment near Artificial Reefs Deployed in the Dysphotic Zone: Exploration of New Artificial Reef Function

Artificial reefs (ARs) have multiple beneficial effects involved in increased fishery production. The present study investigated diatom resting stages in the sediments near ARs at a depth of about 90 m by the combined use of direct microscopic observation and the MPN method, seeking a novel function of AR deployment that potentially increases biological production. Although the concentration of diatom resting stages at A2 (north end station of the AR area), composed mainly of Chaetoceros, was ten times the concentration at A5 (non-reef station), the concentration at A1 (south end station of the AR area) was the same level as at A5. These results suggest that the AR contributes to the accumulation of diatom resting stages while the degree of accumulation is attributed to the arrangement of ARs and their physical environment such as flow directions. Interestingly, live pennate diatoms possessing photosynthetic pigments were constantly observed in all samples despite the low light intensity (≤1.2 µmol photons m−2 s−1), which provides new ecological insight into their biological and physiological characteristics. In this study, the distribution of viable diatom resting stages and live pennate diatoms in the sediment around ARs in a dysphotic zone was revealed for the first time, casting a light on the novel function of ARs potentially enhancing primary production around them.

Side-Scan Sonar Coupled with Scuba Diving Observation for Enhanced Monitoring of Benthic Artificial Reefs along the Coast of Terengganu, Peninsular Malaysia

Since the 1970s, artificial reef (AR) deployment has been one of the common approaches to augment the local production of coastal fish in Malaysia. However, there is a lack of strategy to assess and evaluate the success of pre-deployed AR. Realizing the need for an effective qualitative and quantitative monitoring and evaluation of AR, this study proposes side-scan sonar coupled with scuba diving observation for the enhanced monitoring of pre-deployed Bioceramic Korean (BK) AR along the coast of Terengganu, Peninsular Malaysia. This method employs an integrated side-scan sonar with a data acquisition system for the detection of the precise location of the BK AR which were deployed at Tukun Telaga Batin off the Terengganu coastline in 2003 by the Fisheries Development Authority of Malaysia (FDAM). Following the determination of the exact location of three BK AR areas, a scuba diving team was sent to survey the physical conditions of the AR and assess the feasibility of the AR as an artificial habitat for marine life. The scan sonar images were compared with the captured photographs and videos acquired during the scuba diving session for a comprehensive value-added assessment. The collected data from the scuba diving session were also processed to measure the fish diversity, the fish biomass, and identify the fish community surrounding the AR. Based on the results, the BK AR remained in extremely good condition, physically intact, without significant breakage or damage, and with no major subsidence into the sediment after 19 years of deployment. A total of 108 BK AR modules were detected in three large groups using the mosaicked sonar images. Following cross-examination to validate the AR measurements using the AR’s shadows on the seafloor, the height of the BK AR consistently ranged from 1.7 m to 1.8 m. In addition, 34 species of fish from 14 families and 26 genera were identified, with most species classified as reef-associated (RA) fish with a biomass value of 1173.31 ± 1136.69 kg m−3, indicating the successfulness of the BK AR as fish-aggregating devices (FADs). The growth of hard corals on top of the bioceramic plate of the AR module further supported the diversified community of marine life surrounding the BK AR. In conclusion, the side-scan sonar coupled with scuba diving observation demonstrates an effective qualitative and quantitative technique for the monitoring and evaluation of pre-deployed AR. This strategy is recommended to be utilized to determine the success of pre-deployment AR.

Examining Epibenthic Assemblages Associated with Artificial Reefs Using a Species Archetype Approach

AbstractThe placement of artificial reefs (ARs) influences, to various degrees, a wide range of epibenthic species, whereas most assessments focus on target or focal species. Methods of capturing the responses of many species can inform management about the full range of likely responses of species to the location and arrangement of ARs. Performing many single‐species analyses presents difficulties in interpretation. We used monitoring data from 14 surveys from June 2017 to August 2020 in an area with ARs deployed in the Bohai Sea, China. Both trap and visual census data were collected, and a suite of environmental variables was also collected or estimated for sampled sites and for spatial cells throughout the study area. The data were used to fit a species archetype model (SAM) that relies on the shared responses of species to environmental variables. The many species were grouped into six distinct archetypes. Species membership in the archetypes was confirmed by comparing results to the isometric feature mapping and partitioning around medoids (ISOPAM) approach, which relied on species co‐occurrence applied to the same data. The SAM results were also validated by comparing archetypes determined with fitting to predictions from a single survey that was not used in fitting. The six archetypes identified by the SAM had member species that differed in dependence on substrate types, distance to the nearest AR, distance to the nearest gravel, temperature, dissolved oxygen, time since AR deployment, and sampling method. The importance of the environmental variables was assessed by computing the changes in predicted occurrence probabilities of the archetypes when environmental variables were varied with the other environmental variables set at their minimum, mean, maximum, or optimal values. Species archetype modeling provides a valuable approach for predicting occurrence probabilities of epibenthic species assemblages in response to the locations and arrangement of ARs, and results can inform management related to fishing enhancement and conservation.

Evaluation of Site Suitability for Artificial Reefs Deployment in Southeast Coast of India Using Geographical Information System as a Management Tool

A planned artificial reef (AR) deployment program as part of a fisheries enhancement might be a useful tool for managers to supplement traditional ways to utilize available space and augment local productivity. Several AR deployment initiatives have been carried out globally, but they are rarely subjected to a rigorous site selection process. We created a site selection procedure in this study that includes systematic stages including exclusion mapping, underwater visual transect, benthic composition, seawater quality, and comparative visual mapping. This research focused on restoring the fishing grounds for artisanal fishermen by deploying AR along the southeast coast of India. The results of each stage in the procedure enabled us to choose suitable locations at a target depth with low wave action, no slope, and a good substrate capable of supporting an AR. Analysis of variance (ANOVA-one way) showed significant (p < 0.05) spatial variation for depth, slope, seawater current, salinity, chlorophyll-a, benthic density, and diversity. The geographical information system (GIS) based model output showed space allocation for AR deployment. The GIS methodology for site selection was developed to be easily adaptable to the demands of diverse artificial reef programs. The integrated strategy has proven to be a successful regulatory intervention for AR deployment practices in order to facilitate coastal restoration and management.

A systematic review of artificial reefs as platforms for coral reef research and conservation.

Artificial reefs (ARs) have been used on coral reefs for ecological research, conservation, and socio-cultural purposes since the 1980s. We examined spatio-temporal patterns in AR deployment in tropical and subtropical coral reefs (up to 35° latitude) and evaluated their efficacy in meeting conservation objectives, using a systematic review of the scientific literature. Most deployments (136 studies) were in the North Atlantic and Central Indo-Pacific in 1980s – 2000s, with a pronounced shift to the Western Indo-Pacific in 2010s. Use of ARs in reef restoration or stressor mitigation increased markedly in response to accelerating coral decline over the last 2 decades. Studies that evaluated success in meeting conservation objectives (n = 51) commonly reported increasing fish abundance (55%), enhancing habitat quantity (31%) or coral cover (27%), and conserving target species (24%). Other objectives included stressor mitigation (22%), provision of coral nursery habitat (14%) or source populations (2%) and addressing socio-cultural and economic values (16%). Fish (55% of studies) and coral (53%) were the most commonly monitored taxa. Success in achieving conservation objectives was reported in 33 studies. Success rates were highest for provision of nursery habitat and increasing coral cover (each 71%). Increasing fish abundance or habitat quantity, mitigating environmental impacts, and attaining socio-cultural objectives were moderately successful (60–64%); conservation of target species was the least successful (42%). Failure in achieving objectives commonly was attributed to poor AR design or disruption by large-scale bleaching events. The scale of ARs generally was too small (m2 –10s m2) to address regional losses in coral cover, and study duration too short (< 5 years) to adequately assess ecologically relevant trends in coral cover and community composition. ARs are mostly likely to aid in reef conservation and restoration by providing nursery habitat for target species or recruitment substrate for corals and other organisms. Promoting local socio-cultural values also has potential for regional or global impact by increasing awareness of coral reef decline, if prioritized and properly monitored.

Passive acoustic monitoring complements traditional methods for assessing marine habitat enhancement outcomes

AbstractHabitat enhancement, often accomplished through the introduction of artificial structures, is a common strategy used by marine resource managers to provide habitat subsidies, protect sensitive habitat, and create new fishing opportunities. Traditional monitoring methods for assessing habitat enhancement outcomes face numerous limitations, including dependence on environmental conditions and trade‐offs between sampling frequency and duration. Passive acoustic monitoring (PAM) is not subject to these same limitations and offers many advantages as a complement to traditional monitoring methods. Our team opportunistically monitored the soundscape and community development of a newly deployed artificial reef and compared it to that of a nearby established artificial reef using PAM and underwater time‐lapse videos. Specifically, we compared the sound pressure level (SPL) timeseries, dusk peak in SPL, and dusk power spectrum between the two artificial reefs to evaluate whether and on what timescale the soundscapes converged. Additionally, we tracked temporal patterns in species‐specific vocalizations to identify the trajectory of community development on the new reef. Lastly, we compared the qualitative conclusions drawn from PAM to previously published results from video monitoring of the same two artificial reefs. PAM identified minimal difference in mean low‐frequency SPL between the two reefs at the onset of monitoring. Though the timeseries correlation, dusk SPL, and dusk power spectra all varied across sampling periods, there were periods of low‐frequency soundscape alignment at four and eleven months following artificial reef deployment, associated with the presence of fish chorusing. The high‐frequency timeseries on each reef were well correlated during all sampling periods, despite an initial SPL difference of 17 dB. Throughout monitoring, high‐frequency sound levels became more similar between the reefs but did not converge. While video monitoring suggested that demersal species did not colonize the reef until five months post‐deployment, patterns in species‐specific vocalizations suggested that toadfish (Opsanus sp.) a cryptic, demersal species may have colonized the new reef within two weeks. Our findings demonstrate that passive acoustic monitoring is a useful complement to traditional methodologies and can provide a more holistic view of community development than visual monitoring alone.

Representative benthic habitat mapping on Lovina coral reefs in Northern Bali, Indonesia

Abstract. Kartikasari A, Pristianto T, Hanintyo R, Ampou EE, Wibawa TA, Borneo BB. 2021. Representative benthic habitat mapping on Lovina coral reefs in Northern Bali, Indonesia. Biodiversitas 22: 4766-4774. Satellite optical imagery datasets integrated with in situ measurements are widely used to derive the spatial distribution of various benthic habitats in coral reef ecosystems. In this study, an approach to estimate spatial coverage of those habitats based on observation derived from Sentinel-2 optical imagery and a field survey, is presented. This study focused on the Lovina coral reef ecosystem of Northern Bali, Indonesia to support deployment of artificial reefs within the Indonesian Coral Reef Garden (ICRG) programme. Three specific locations were explored: Temukus, Tukad Mungga, and Baktiseraga waters. Spatial benthic habitat coverages of these three waters was estimated based on supervised classification techniques using 10m bands of Sentinel-2 imagery and the medium scale approach (MSA) transect method of in situ measurement.The study indicates that total coverage of benthic habitat is 61.34 ha, 25.17 ha, and 27.88 ha for Temukus, Tukad Mungga, and Baktiseraga waters, respectively. The dominant benthic habitat of those three waters consists of sand, seagrass, coral, rubble, reef slope and intertidal zone. The coral reef coverage is 29.48 ha (48%) for Temukus covered by genus Acropora, Isopora, Porites, Montipora, Pocillopora. The coverage for Tukad Mungga is 8.69 ha (35%) covered by genus Acropora, Montipora, Favia, Psammocora, Porites, and the coverage for Baktiseraga is 11.37 ha (41%) covered by genus Montipora sp, Goniastrea, Pavona, Platygyra, Pocillopora, Porites, Acropora, Leptoseris, Acropora, Pocillopora, Fungia. The results are expected to be suitable as supporting data in restoring coral reef ecosystems in the northern part of Bali, especially in Buleleng District.

An assessment of marine and coastal diversity of Covelong, Chennai, India

Covelong coast situated in north Tamil Nadu has a unique habitat comprising of intertidal rocky and sandy areas. Located near the mouth of Muttukadu brackish water, Covelong is considered as one of the sites for artificial reef deployment by the state government. With all these coastal habitats, it can be assumed that this area supports remarkably diverse marine life forms. The present work represents the first-of-its-kind study where we have assessed the fish landing center, intertidal zones, and beach areas to assess the common marine and coastal diversity of Covelong. A total of 224 species of marine flora and fauna belonging to 135 families, 61 orders, 20 classes, and 10 phyla were reported from the fish landing center, intertidal rocks and sands, and beach strandings. The present findings will provide baseline information to marine enthusiasts, marine biologists, and ecologists for their future research on the Covelong coast. We would recommend in favor of declaring the Covelong coast as one of the long-term monitoring sites for ecological studies, as this area is much influenced by natural and anthropogenic activities.

Fish assemblages associated with natural, transplanted, artificial, and accidental reefs in Puerto Rico

When accompanied with well-informed management actions, active restoration strategies such as coral gardening and deployment of artificial reef structures can help mitigate negative effects of human impact on fish assemblages associated to natural reefs. However, ecological patterns of variation of fish assemblages associated with artificial reefs are poorly understood. From mid-April 2018 to mid-June 2019, we compared fish assemblages associated to one of four types of reef structures: natural reefs (NR), transplanted reefs (TR; i.e., Acropora palmata colonies), concrete modules or restoration reefs (RR), and accidental reefs (AC; submerged docks and shipwrecks) across twelve sites around Puerto Rico. Response variables were abundance, biomass, and number of species per sample and these were correlated with environmental factors that could influence the observed patterns of spatial and temporal variation in fish assemblages. Despite natural seasonal fluctuations, differences in fish assemblages between reef types were generally greater than differences among sites, although less obvious between TR and NR. Based on these results, and on the assumption that the general aim of artificial reef deployment is to mimic natural reef function, we highlight the need for management strategies that are tailored to site-specific or reef-specific goals and needs. Our study reinforces the importance of multivariate statistics to recognize patterns of spatial and temporal variation at the smallest spatial scales, understand ecosystem function, and to improve the effectiveness of management actions concerning active restoration strategies like coral gardening and creation of artificial reef habitats.

Using ecological evidence to refine approaches to deploying offshore artificial reefs for recreational fisheries

Artificial reefs have many applications but are best known for their deployments to enhance recreational fisheries by creating new habitat in areas where natural reef is otherwise limited. The expectation is that fish assemblages will take up residence on artificial reefs and that these assemblages will become at least similar, if not more diverse and abundant, to those on natural reefs. Although designed, purpose-built artificial reefs are becoming more widely used in support of recreational fisheries and many of the historic issues have been resolved, conservation practitioners and managers still face challenges as to the type, number, and arrangement of structures and where to deploy them to maximize benefits and minimize risks. The ecological literature was reviewed to develop and enhance contemporary principles of artificial reef best practices for utilization. Our review identified optimal shapes, vertical relief, void spaces, and unit arrangements for increasing volumes and diversity of catch to recreational fishers and we provide a tool for identifying the least constrained areas for artificial reef deployment. We suggest; (a) monitoring of noncatch motivators in combination with quantitative indicators of the fishing activity (e.g., catch rate and effort) will provide the best understanding of success or failure of an artificial reef deployment; (b) choosing target species for informing purpose-built artificial reef designs to be reef-associated, demersal, philopatric, territorial, and obligatory reef species that are desired by local recreational fishers; and (c) considering the ecosystem services provided by artificial reefs beyond those associated with recreational fishing.

Artificial reefs in the North –East Atlantic area: Present situation, knowledge gaps and future perspectives

Artificial reefs have been deployed in multiple regions of the world for different purposes including habitat restoration and protection, biodiversity and fish stock enhancement, fisheries management and recreation. Artificial reefs can be a valuable tool for ecosystem protection and rehabilitation, helping mitigate the effects of anthropogenic impacts that we face today. However, knowledge on artificial reefs is unevenly distributed worldwide, with some regions having much more quality information available and published (e.g. European Mediterranean Sea area), while others, for instance the North-East Atlantic area, do not. Here, we provide a characterization of purposely built artificial reefs in North-East Atlantic area based on all available literature (i.e. research papers and reports), highlighting the needs and gaps that are vital for establishing future perspectives for artificial reef deployment and research. In the North-East Atlantic area, sixty-one purposely built artificial reefs have been deployed since 1970, mostly between the years 1990–2009, with Spain being the country with the highest number of artificial reefs. The most reported purpose for their deployment is fisheries productivity and habitat/species protection, although, most artificial reefs are multipurpose in order to maximise the benefits of a given financial investment. The majority of artificial reefs were submerged at < 50 m, mainly between 10 and 20 m of depth. The most used designs were cubic blocks and complex designs made by an array of combined shapes, which mostly consist of concrete (79%). From all the analysed data on artificial reefs, 67% of the cases reported surveys to assess biodiversity after the deployment. However, in 26% of those cases, data was not available. When data was available, only 31% of cases reported long-term biomonitoring surveys (3 years or more). Based upon these findings, we noticed a general lack of scientifically robust data, including records of species and abundance of both fish and invertebrates, as well as macroalgae, preventing an adequate determination of the best balance between shape, construction material and bio-colonization. Critiques and suggestions are discussed in the light of currently available data in order to perform more efficient research, evaluation and functioning of future artificial reefs.