Artificial Reefs Research Articles

Moats & comets - A methodology to explore for submerged prehistory at sea floor erosional features formed at artificial reefs, Atlantic continental shelf, GeorgiaUSA.

Our primary objective is to demonstrate a method that uses marine processes, principally seafloor scour, to broadly expose prehistoric landforms and associated localities. Too often, the loss of prehistoric strata to scour processes such as ravinement during broad-scale, continental shelf transgressions, are decried without the recognition of the potential for erosion at the local scale can expose those same strata for systematic study. The analysis of sea floor erosional features formed around artificial reefs by turbulent flows in the Georgia Bight have used interferometric side-scan sonar (SSS), Remotely Operated Vehicles (ROVs), ultra-high-definition videography (UHD), and sedimentological, palynological, paleontological, archaeological analytical techniques. These techniques were integrated within a geoarchaeological methodology focused on exploring the Continental Shelf for preserved evidence of prehistoric landforms, flora and fauna once thereon. A stepwise protocol was developed to first gather interferometric side-scan sonar data to be then processed by commercial software packages such as HYPACK Hydrographic and HYSWEEP together with HYSCAN and SONAR Wiz software. The sonar mosaics were imported to ArcGIS/QGIS software to characterize scour features/targets around artificial reefs that had exposed paleo-land surfaces previously obscured by the modern palimpsest sand sheet. Analysis of scours and depressions - “moats and comets” - adjacent to reef structures were evaluated using the profile tool within the HYPACK-HYSWEEP editor package. Symbology for the bathymetric raster layers was edited to provide a clear contrast and measurement at scour features. Measured GIS images were then classified as to scour extent and depth with respect to prevailing current directions responsible for producing turbulence. A ranking of the artificial reefs by factors such as scour depth and extent was used to guide subsequent investigation by ROVs. Sediment cores and grab samples were collected, and those samples underwent particle size analysis (PSA), macro-and micro-botanical analyses. All data – geophysical, GIS, video and geological – were collated and synthesized to produce an assessment of the potential of sea floor scour features to expose previously buried geomorphological/geological, paleontological and/or archaeological features of interest.

Habitat Fragmentation Enhances the Difference between Natural and Artificial Reefs in an Urban Marine Coastal Tract

Coastal urbanization and the consequent proliferation of artificial structures greatly impact rocky reef communities, productive and diverse marine environments that play a crucial role in the functioning of broader coastal ecosystems. This study, conducted along a 7 km stretch of coastline at increasing distance from the port of Genoa (Ligurian Sea), investigated whether the alternating presence of artificial and natural reefs leads to discernible differences in the biota inhabiting these two reef types. The study area is one of the most anthropized areas of the Mediterranean Sea, exhibiting nearly 60% coastal artificialization, which severely impacts coastal ecosystems, favouring the replacement of sensitive species with more tolerant species. Ten reefs (5 natural and 5 artificial) were surveyed by scuba diving at about a 6-m depth, employing quadrats of 50 cm × 50 cm to estimate visually the percent cover of conspicuous sessile organisms. The artificial reefs hosted a similar number of species (18) to their natural counterparts (19) but exhibited a distinct community composition: the former were especially characterized by Jania rubens and filamentous algae, with the latter characterized by Peyssonnelia squamaria and Mesophyllum lichenoides. This difference, however, became negligible where coastal habitat fragmentation (here measured with a purposely devised Fragmentation Index) was minimal. Reducing fragmentation may therefore represent a management strategy to minimize the potential impact of artificial structures on marine biodiversity.

Contribution of artificial reefs on fisheries productivity in the Sultanate of Oman from the fishermen perspective

Artificial reefs enhance the biological, physical, and socioeconomic processes associated with natural reefs. Omani fishermen have often used tires and old car frames to create traditional artificial reefs (TARs) that attract fish. The Ministry of Agriculture, Fisheries, Wealth, and Water Resources of the Sultanate of Oman (MAFWR) constructed ministry artificial reefs (MARs) throughout the Omani coasts. To assess fishermen's perceptions of whether MARs enhance fisheries productivity and are used effectively, a survey was conducted in North Al-Batinah with 96 fishermen. Most survey questions were answered on a 5-point Likert scale, with some asking about their personal opinions about MARs. Result showed that approximately 55% of the respondents owned TARs and 45% did not. Fishermen did not accept the idea of fishing within MAR sites, both old and new, and preferred fishing within TARs or in open waters. The results also demonstrated that fishermen mostly understood the role of MARs in boosting the yield and diversity of Wilayat fisheries. Approximately 91% of the interviewees thought that TARs were fish aggregation tools, and 88% believed TARs were fishery enhancing tools. Based on these findings, recommendations have been made to improve awareness on the role and locations of MARs. In the future, the use of MARs should be systematically regulated by the government.

Vessels and aircraft are chronic sources of anthropogenic noise in coastal marine and terrestrial soundscapes on Long Island, New York

Passive acoustic data collected during 2020 and 2021 were used to monitor changes in both terrestrial and underwater soundscapes, as well as human activity from aircraft and vessels. Passive acoustic data were collected at two artificial reefs south of Long Island, as well as along ocean beaches in Southampton, NY. At the artificial reefs, vessel noise was recorded more frequently during 2020 than in 2021. Commercial vessels and multi-user charter fishing vessels were more abundant during 2020. Peaks in power spectral density occurred at 60, 90 and 120 Hz in 2020 and 2021, which are frequencies consistent with noise generated by commercial vessels, suggesting that vessels are a significant contributor to the soundscape of the artificial reefs. In the terrestrial environment, noise generated by aircraft was more common during 2021. Peaks in power spectral density were measured around 160 and 290 Hz at one of the ocean beach sites. These frequencies are consistent with noise generated by aircraft. This study documents the chronic extent of anthropogenic noise in both the underwater and terrestrial environments of Long Island, NY, as well as quantifies the occurrence of various noise sources in these habitats.

Habitat Enrichment Causes Changes in Fish Behavioural Characteristics: A Case Study of Sparus latus.

To better understand the habitat preferences and behavioural ecology of Sparus latus, we performed an experiment using box-shaped reefs as habitat enrichment materials, allowing us to determine the behavioural strategies and drivers involved in the response to different enrichment structures. The results showed that the first contact time of S. latus was negatively correlated (Pearson's correlation, p < 0.005) with the distribution rate in the artificial reef area. Enrichment structures affected the habitat preferences of S. latus, and there was a significant difference in the average distribution rate between the control and treatment groups (Adonis, p < 0.001). The opening ratio (Adonis, R2 = 0.36) explained the distribution difference of S. latus better than the opening shape (Adonis, R2 = 0.12). In the absence of an enrichment structure, S. latus remained more active during the daytime, exhibiting poor clustering, while in the presence of an enrichment structure, S. latus exhibited clustered movement at night. The opening ratio was negatively correlated with the average interindividual distance (Spearman's correlation, p < 0.01) and showed a significant positive correlation with the average distribution rate in the reef area (Spearman's correlation, p < 0.001), indicating that the reef opening ratio significantly affected the reef-tropism and clustering behaviours of S. latus. The light intensity was negatively correlated with the average distance moved, and the average speed (Spearman's correlation, p < 0.05) was significantly positively correlated with the reef first contact time (Spearman's correlation, p < 0.001), indicating that the light intensity affected the exploration and activity patterns of S. latus. These results provide a research basis for analysing the pattern and process of fish proliferation induced by artificial reef habitats.

Preliminary investigation and life cycle assessment of artificial reefs with recycled brick-concrete aggregates

An economical and environment-friendly artificial reef concrete using fully recycled brick-concrete aggregate as raw material was proposed. This study investigates the mechanical properties, drying shrinkage, chloride ion penetration, and biological adaptability of the reef. A comparative analysis is conducted on the environmental impacts (EI), carbon emission impact and cost efficiency of artificial reefs, considering natural aggregate concrete and recycled brick-concrete aggregate concrete at the material level. The results indicate that the use of recycled brick-concrete aggregates can achieve service performance equivalent to that of natural aggregates. Field investigations involving samples immersed in seawater for six months reveal the positive trapping effects of recycled materials on aquatic organisms. The Life Cycle Assessment (LCA) results reveal that achieving a 100 % replacement rate of recycled brick concrete aggregate (RBCA) creates a positive feedback loop for carbon emissions when appropriately incorporating industrial waste materials like fly ash and silica fume. In comparison to ordinary concrete, the utilization of recycled materials can significantly reduce construction costs, up to 63.7 %, thereby presenting notable economic advantages.

Recreational value of different coral reefs richness levels in Oman

Coral reefs in Oman boast remarkable biodiversity and distinct features, yet their economic contribution remains largely unexplored, making this topic seriously under-researched. This study addresses this gap by aiming to estimate the recreational value of ecosystem services offered by natural and artificial coral reefs along Oman's coastline, a valuable asset that falls under the category of public goods that has never been assessed. Moreover, the study delves into the impact of varying reef richness levels, indicating biodiversity levels, on overall recreational value in this seldom-studied region with significant coral reef resources. Notably, this research marks the first attempt in the literature to examine the influence of different richness levels of reefs on recreational value. A survey was conducted to evaluate the recreational value of ecosystem services provided by coral reefs using Travel Cost Method. Coral reefs are found to provide an annual consumer surplus of 187,763 OMR (about 487,727 USD), emphasizing their substantial economic value. Greater biodiversity within a reef corresponds to a higher preference among recreationists, leading to increased economic benefits and enhanced consumers satisfaction. The substantial increase in recreational demand at sites with high reef richness levels underscores the importance of these ecosystems not just for their intrinsic natural value but also for their contribution to the tourism sector. It is essential for decision-makers to focus on the preservation of existing coral reefs as a primary concern, prior to contemplating the creation of additional reefs to enhance marine tourism. Managerial implications•Coral reefs not only draw more recreationists but also significantly enhance consumer surplus and satisfaction•The richer the biodiversity of a reef, the more it is preferred, deriving greater economic value and consumer satisfaction•Oman's coral reefs provide a consumer surplus of 187,762.955 OMR (487,726.84 USD), emphasizing their economic significance•Policymakers should prioritize maintaining existing coral reefs before considering the development of new ones•Conserving and enhancing coral reefs is crucial for ecological and economic reasons, benefiting tourism-related activities

Repurposing oil and gas infrastructure as artificial reefs – a global perspective

More than 7000 offshore oil and gas (O&amp;G) installations are found across 53 countries throughout the world’s oceans. During their life span, these structures provide a habitat for marine life and can support diverse assemblages. At the end of planned service life, they are decommissioned which usually involves the complete removal of infrastructure from the ocean, resulting in the loss of these marine communities. Various countries have repurposed O&amp;G platforms as artificial reefs as an alternative solution to decommissioning, such as the Rigs-to-Reefs (R2R) program developed by the United States (US). The repurposing of O&amp;G platforms may have benefits in preserving or enhancing ecological communities, as well as reducing the impacts and costs associated with removal and disposal onshore. The placement of O&amp;G platforms in the ocean as artificial reefs demands prudent planning and high-level management to ensure the anticipated benefits are delivered and potential impacts are managed. The US National Artificial Reef Program (NARP) along with the R2R program provides guidelines on various aspects of artificial reef use, including planning, site selection, design and management. Since 1980, the US has successfully converted more than 593 O&amp;G platforms to permanent artificial reefs due to the active participation and support of O&amp;G operators, government, local fishing and diving communities. Other countries are also taking initiatives to repurpose their O&amp;G infrastructure. The aim of this paper is to identify key considerations in the repurposing of O&amp;G infrastructure as artificial reefs, using the US R2R program and other geographies as examples.

Estimation of Artificial Reef Pose Based on Deep Learning

Artificial reefs are man-made structures submerged in the ocean, and the design of these structures plays a crucial role in determining their effectiveness. Precisely measuring the configuration of artificial reefs is vital for creating suitable habitats for marine organisms. This study presents a novel approach for automated detection of artificial reefs by recognizing their key features and key points. Two enhanced models, namely, YOLOv8n-PoseRFSA and YOLOv8n-PoseMSA, are introduced based on the YOLOv8n-Pose architecture. The YOLOv8n-PoseRFSA model exhibits a 2.3% increase in accuracy in pinpointing target key points compared to the baseline YOLOv8n-Pose model, showcasing notable enhancements in recall rate, mean average precision (mAP), and other evaluation metrics. In response to the demand for swift identification in mobile fishing scenarios, a YOLOv8n-PoseMSA model is proposed, leveraging MobileNetV3 to replace the backbone network structure. This model reduces the computational burden to 33% of the original model while preserving recognition accuracy and minimizing the accuracy drop. The methodology outlined in this research enables real-time monitoring of artificial reef deployments, allowing for the precise quantification of their structural characteristics, thereby significantly enhancing monitoring efficiency and convenience. By better assessing the layout of artificial reefs and their ecological impact, this approach offers valuable data support for the future planning and implementation of reef projects.

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.

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.

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.

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.

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

The distribution of fish eggs and larvae (ichthyoplankton) reflects spawning and nursery areas as well as dispersal routes. This study’s goal is to demonstrate how the identification of ichthyoplankton species and stages and their spatial distribution among natural reefs (NRs) and artificial reefs (ARs) may serve as decision-making tools in conservation and fishery management. Natural reefs exhibited an eight-times higher abundance of eggs, as well as the highest abundance of larvae in the yolk-sac and preflexion phases. In contrast, ARs had the highest abundance of larvae in the flexion and postflexion phases. Natural reefs may serve as breeding grounds for Scaridae, Labridae, and Mugilidae; whereas, ARs may serve as breeding sites for Lutjanidae, Synodontidae, Carangidae, Fistularidae, and Haemulidae. Our study revealed differences between ARs and NRs, which demonstrate the potential of artificial reefs to expand the supply and settlement options of reef fishes and consequently can lead to increased fish production with potential benefits to adjacent fishing areas through connectivity. Thus, ARs as no-take sites can be effective tools for both fishery management and biodiversity conservation. The findings highlight the potential use of ichthyoplankton tools and the importance of considering both types of reefs in marine conservation and management efforts.

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.

Reefense: Design Of A Porous Modular Hybrid Reef For Coastal Protection

Hybrid artificial reef structures can be designed to promote the development of a self-sustaining habitat for reef organisms while simultaneously enhancing the extent to which they provide coastal protection. Such hybrid structures offer many additional ecosystem benefits over conventional engineering structures that are used to provide coastal protection. Here, we investigate the wave attenuation capacity of engineered oyster reef modules that have been designed through the DARPA initiative Reefense: A Mosaic Oyster Habitat for Coastal Defense. The modules are designed with significant porosity (through misaligned holes), shelves to facilitate oyster recruitment, and an interlocking mechanism to maximise reef stability.

Wave Basin Experiments Of Wave-Driven Hydrodynamics Over Submerged Coastal Structures And Artificial Reefs

Submerged coastal structures, such as submerged breakwaters and artificial reefs, modify incident wave fields and alter a wide range of nearshore hydrodynamic processes. Submerged breakwaters are usually designed for a singular function of wave attenuation; whereas nature-based artificial reef structures aim to both attenuate wave energy while enhancing ecosystem services, including the creation of habitat for marine organisms and the promotion of biodiversity. However, to date the application of artificial reefs has remained more limited due to the poorer understanding of how reefs influence key nearshore processes that determine their effectiveness. Existing research on submerged breakwaters has mostly focused on quantifying the wave transmission, which is ratio between the incident wave energy onshore and offshore of the reefs (e.g., van Gent 2023). The wave transmission coefficient has conventionally served as a primary design criterion related to the effectiveness of reefs in offering coastal protection. However, a meta-analysis of the shoreline response to constructed submerged breakwaters found that in the majority of cases erosion occurred in their lee (Ranasinghe and Turner., 2006), which demonstrates our limited knowledge on how reefs modify coastal processes. Wave-reef interactions can lead to the generation of mean (wave-averaged) currents and water levels (setup). Numerical modelling studies have found that two and four-cell mean circulation patterns can develop in response to changes to the wave field caused by submerged structures (Ranasinghe et al., 2006, da Silva et al., 2022). A two-cell circulation is characterized by diverging currents behind the reefs and at the shoreline, which could lead to an erosive shoreline. In contrast, a four-cell circulation is characterized by diverging currents in the immediate lee but converging currents at the shoreline, which would result in beach accretion. While these modelling studies advanced the understanding of how reefs influence shoreline hydrodynamics, the absence of comprehensive experimental observations replicating submerged coastal structures has hindered their rigorous validation. Here we present the findings of an extensive set of 3D wave basin experiments that were designed to investigate the detailed wave-driven hydrodynamics around submerged coastal structures subject to a range of wave conditions, water levels and reef layouts.

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.

Overtopping Reduction By Artificial Reefs

Artificial or Engineered reefs are primarily developed for enhancing the ecological system. In Guidelines for the Placement of Artificial Reefs (UNEP, 2009) they are described as "An artificial reef is a submerged structure deliberately constructed or placed on the seabed to emulate some functions of a natural reef such as protecting, regenerating, concentrating, and/or enhancing populations of living marine resources." Often these artificial reefs have either a complex shape inspired by biomimicry (e.g. Coastruction) or a more regular shape, designed to function as modular blocks that can be easily placed on top of each other (e.g. Reefy). In many parts of the world, application of these engineered elements on top of existing shallow reefs may be a solution to not only enhance the ecosystem but also to increase the safety level of the hinterland. Also, in light of climate change and further increasing water levels, the artificial reefs may be a valuable alternative to reduce wave overtopping and prevent the land for extreme flooding. To quantify the possible effect of such artificial reefs in more shallower areas, physical model testing have been performed in which both overtopping was measured with and without the use of engineered elements. Shallow water depths have been chosen here, since the reef should induce wave breaking, resulting in the wave energy to decrease. The performance of these engineered elements in relation to its submergence has been investigated and a reduction coefficient has been developed.

Isochrysis Crisis

Isochrysis galbana, a brown algae, was trialed to grow at the CFK aquaculture lab but failed until we tried comparing different tank salts to create a wellbalanced base. Our objective was to demonstrate and compare the different saltwater mixes that can be used in cultivating brown algae. Isochrysis galbana and other green algae that are grown at the CFK lab play a very important part in the aquaculture system. Algae is used as a good source of food and nutrients for many primary producers. Algae are one of the most important animals on earth. They create most of the oxygen that we breathe, and they filter every part of the water around the world. Brown algae is known around Florida because of certain species, like sargassum. We are currently having an issue with sargassum, so learning about different brown algae species can benefit everyone around the world. If Isochrysis sp. is kept at a stable salinity of 35ppt then it will easily and successfully grow. The samples were grown according to the standard measures but with different salt bases one was raw salt water, live aquaria and REEF salt. The raw seawater sample grew over a 1–2-day period with salinity that usually stayed around 40. The samples mixed into each artificial reef salt took about a week or more to grow color and cultivate the algae.