First Report of Potential Coral Disease in the Coral Hatchery of Thailand

In this study, coral disease was first reported in the coral hatchery in Thailand. Disease were usually found on corals aged two to five years old during the months of November to December of each year. To identify bacterial strains, culture-based methods for strain isolation and molecular techniques of the 16S rRNA gene analysis were used. The resuts showed that the dominant genera of bacteria in diseased corals were Vibrio spp. (comprising 41.01% of the isolates). The occurrence of the disease in the coral hatchery can have a significant effect on the health and survival of juvenile corals before being transplanted to natural reefs for restoration.

Assessment of the Performance of an Artificial Reef Made of Modular Elements through Small Scale Experiments

Artificial reefs have proven to be an optimal and effective solution in stabilizing coastlines around the world. They are submerged structures that imitate the protection service provided by natural reefs accomplishing the functions of dissipating wave energy and protecting beach morphology, but also being an ecological solution. In this paper, 2D small-scale experiments were performed to analyze the hydrodynamic, morphological, and ecological behavior of an artificial reef constructed of modular elements. Two typical beach-dune profiles were constructed in a wave flume over which two locations of an artificial reef were tested. From these tests, transmission coefficients were obtained as well as the beach profile response to the presence of the artificial reef. These results are used to discuss about the hydrodynamic, morphological, and ecological performance of the artificial reef. The proposed artificial reef showed good morphological performance while its hydrodynamic function had limited success. In turn, the ecologic performance was theoretically addressed.

Temporal and spatial variation in adult and juvenile mobile fauna associated with natural and artificial coastal habitats

Coastal habitats are important for commercially exploited and protected species of fish and larger mobile invertebrates. The addition of artificial structures within the marine environment has the potential to alter the connectivity between habitats and to affect metapopulations of a region. Baited remote underwater videos (BRUV) were used to investigate the spatial and seasonal variation in abundance of adult and juvenile mobile species associated with subtidal natural and artificial habitats within Poole Bay on the south coast of England in 2019. Metrics included the relative maximum abundance (MaxN), number of species seen (S), assemblage structure and size range of fish. Higher values of MaxN and S were recorded on artificial structures in the spring and early summer; however, this pattern was reversed by mid-summer and early autumn when more fish were recorded on the natural reefs. Yet overall differences in MaxN and S between habitats were not significant. Differences in assemblage composition between habitats varied monthly, but this was mostly driven by particular sites. Although most fish observed were juveniles, there were some seasonal differences in the size of fish using natural and artificial sites, especially bib (Trisopterus luscus), black bream (Spondyliosoma cantharus), bass (Dicentrarchus labrax) and pollack (Pollachius pollachius). The artificial habitats in this region appeared to be important in certain months, so temporal studies of this type need to be incorporated within surveys, particularly those in proximity to protected areas.

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.

An Assessment of Computational Fluid Dynamics as a Tool to Aid the Design of the HCMR-Artificial-ReefsTM Diving Oasis in the Underwater Biotechnological Park of Crete

Since recreational diving activities have increased in recent decades, resulting in additional environmental pressure on the coastal zone, the deployment of artificial reefs as a conservation strategy to divert mass ecotourism from fragile natural reefs has been proposed and realized in many areas of the world. Twelve units of a patented naturoid artificial reef technology developed by the Hellenic Centre for Marine Research (HCMR) were deployed in 2015 in the Underwater Biotechnological Park of Crete (UBPC) in order to create an experimental diving oasis and investigate the potential of achieving this aim for the over-exploited coastal ecosystems of this part of the Eastern Mediterranean. Assessment of the degree of establishment of artificial reefs and their ability to mimic natural ecosystems is often monitored through biological surveys and sampling. The measurement of the chemical, physical, and hydrodynamic characteristics of the water mass surrounding artificial reefs is also essential to fully understand their comparison to natural reefs. In particular, the flow field around reefs has been shown to be one of the most important physical factors in determining suitable conditions for the establishment of a number of key species on reef habitats. However, the combination of biological establishment monitoring and realistic flow-field simulation using computational fluid dynamics as a tool to aid in the design improvement of already existing reef installations has not been fully investigated in previous work. They are often reported separately as either ecological or engineering studies. Therefore, this study examined a full-scale numerical simulation of the field flow around individual already installed naturoid reef shapes, and part of their present arrangement on the sea bottom of the UPBC combined with the field-testing of the functionality of the installed artificial reefs concerning fish species aggregation. The results show that the simulated flow characteristics around the HCMR diving oasis artificial reefs were in good general agreement with the results of former studies, both for flows around a single deployed unit and for flows around a cluster of more than one unit. The results also gave good indications of the performance of individual reef units concerning key desirable characteristics such as downstream shadowing and sediment/nutrient upwelling and resuspension. In particular, they confirmed extended low flow levels (less than 0.3 m/s) and in some cases double vortexes on the downstream side of reef units where observed colonization and habitation of some key fish species had taken place. They also showed how the present distribution of units could be optimized to perform better as an integrated reef cluster. The use of computational fluid dynamics, with field survey data, is therefore suggested as a useful design improvement tool for installed reef structures and their deployment arrangement for recreational diving oases that can aid the sustainable development of the coastal zone.

A large eddy simulation study of the inshore nutrient uplift process: The role of topography

<p>Artificial fish reefs are the underwater structures placed on the ocean floor to simulate some characteristics of natural reefs. The onshore current can be transformed into upwelling under the influence of artificial fish reefs, thus the nutrient at the bottom of the near shore can be raised, which increases the prey of plankton and fish yield. In order to investigate this phenomenon, a 3D large eddy simulation (LES) of the ocean boundary layer was combined with four different types of artificial fish reef terrains (square, convex-fan, isosceles right triangle, concave-fan). In the near surface, almost only the square terrain can uplift the nutrient, which brings about the most uniform nutrient distribution. Based on the size of integral values of nutrient concentration in the upper part of the four reefs, they are listed as follows: square terrain, convex-fan terrain, isosceles right triangle terrain, concave-fan terrain decreases (from largest to smallest). What is more, the integral values of the four terrains reduce exponentially. Because the nutrient flow encounters the square terrain’s vertical plane, it has a larger vertical velocity. Nevertheless, for convex-fan terrain and isosceles right triangle terrain, their slopes are smoothly, resulting in poor lifting effect. Meanwhile, compared with the other three types of terrains, the concave-fan terrain can prevent the overflow of nutrients better. Among those four reefs, it can be found the square-shaped artificial fish reef is the best one for uplifting the nutrient.</p>