• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.93-102
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• 2020

This study investigated the dif usion characteristics of Ecklonia cava spores around marine forest reefs. For this purpose, a numerical analysis was conducted using field observations in the target area and an EFDC model. Based on the results of field observations and the EFDC model, Flow-3D was performed on three types of marine forest reefs, mamely triangular pyramid reef, double-dome reef, and ribbed reef, to monitor the movement direction and maximum movement distance for E. cava spores. As a result, the equilaterally triangular pyramid reef and double-domed reef were found to have a maximum settlement of spores of 10 m in the northwestern direction and 6 m in the western direction. The ribbed reef had a maximum settlement of spores at 4m. These results show that consideration of the diffusion characteristics of E. cava spores when the seaweeds are installed can increase the effectiveness of the algae as substrate of adhesion.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.4
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• pp.220-225
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• 2007

The succession of marine benthic algae and the restoration of an artificial seaweed forest on a porous type (shaped half saw teeth) artificial reef at Jeju island, Korea was studied. Young thalli of Sargassum horneri and Ecklonia cava were attached to different artificial substrates. In general, the succession on the artificial reefs led from filamentous algae to perennial algae and involved more than 25 species that are useful fishery resources, including E. cava. Coralline algae were dominant on the artificial reefs at the Kangjung site. The maximum algal biomass on the artificial reef in October 2005 was $1,990g/m^2$ at Biyang. In conclusion, a climax community and seaweed forest can be attained one year after the substrate is constructed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2307-2312
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• 2014

Artificial reef refers to various structures that facility to construction field format and spawning of marine organisms, sea ranch, forest of the sea, and sea jungle artificially in water, Build a production stable base of marine products, thereby contributing to an increase in the income of fishermen. In the management of an artificial reef, the calculation of the number of square reefs may be that it is a method to perform the submersible is an important part of maintenance is correct. However, cost and diving personnel, depending on the diving situation, there is a difficult thing to implement to coast across the country. Therefore, In this study, We calculated the volume using the multi-beam Echo Sounder and side scan sonar for the reefs of the rectangle are the existing installation. And proposes the improvement of the estimation in accordance with the volume coefficient reef.

• Journal of Advanced Research in Ocean Engineering
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• v.2 no.4
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• pp.169-178
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• 2016

Recently, artificial reefs (ARs) have been frequently used primarily owing to the development in AR materials and projects for relatively complicated, large ARs. Among several engineering issues of ARs, wake region of an AR has been characterized because these regions have a high probability of recruiting seaweed spores, providing an energy saving zone, and facilitating deposition of sediments, nutrients, and bio-deposits. To characterize an efficiency index of an AR wake region and its dependency on the prevailing water flow directions, this study proposes a so-called efficiency index diagram. This characterization is done by normalizing the wake volumes with respect to the real AR volume and illustrating how efficiency indices vary with respect to the inlet flow directions. As a result, according to the diagram characteristics such as an averaged efficiency index, fundamental symmetric angle, secure angles, and principal directions, we can easily figure out how a target AR should be aligned along the main water flows to maximize the wake region around the AR. In addition, six ARs are considered and their efficiency index diagrams are illustrated to pinpoint the physical characteristics.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.4
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• pp.1042-1056
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• 2016

To evaluate the wake regions of six artificial reefs (ARs) frequently used in the marine forest creation project in Korea, we consider the effect of water flow directions on the wake regions and accordingly propose a wake region diagram, which is characterized by parameters such as wake volume fluctuations, averaged wake volume, fundamental symmetric angle, secure angle, and principal direction. To demonstrate the parameters, seven water flow directions (0 to $90^{\circ}$) were considered and consequently the variations in wake volumes were investigated by using the concept of wake volume, adopting element-based finite volume method, and utilizing numerical flow domain and boundary conditions. From the analysis results, it was shown that the wake region diagrams have a period of either 45 or $90^{\circ}$ according to the geometrical symmetry of each artificial reef. Also, it was found that the secure angle ranges fluctuate depending on the shapes and sizes of the artificial reefs considered. Thus, it is demanded to consider those parameters during installation of artificial reefs for establishing a larger wake region and accordingly attracting more marine fauna and flora in the region.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.639-646
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• 2021

In this study, we located concrete substratum covered by oyster shells in the coastal area of Gijang-gun, Busan, South Korea, and monitored changes in coverage of macroalgae for approximately a year from January 2020 to determine the potential for sea forest restoration and resourceization of the oyster shells. At the start of monitoring, we observed that macroalgae coverage of the oyster-shell-covered concrete substratum (treatment) was 10 - 80 %, whereas no macroalgae were attached to the normal concrete substratum (control). By November, macroalgae coverage of the treatment had increased by 49 % compared to that of the control. We concluded that covering oyster shell on a sea forest reef can promote macroalgae establishment and the possibility of sea forest restoration by the resourceization of oyster shells.

• Ocean and Polar Research
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• v.35 no.4
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• pp.415-425
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• 2013

In order to understand phytoplankton and bacterial distribution in tropical coral reef ecosystems in relation to the mangrove community, their biomass and activities were measured in the sea waters of the Chuuk and the Kosrae lagoons located in Micronesia. Chlorophyll a and bacterial abundance showed maximal values in the seawater near the mangrove forests, and then steeply decreased as the distance increased from the mangrove forests, indicating that environmental conditions for these microorganisms changed greatly in lagoon waters. Together with chlorophyll a, abundance of Synechococcus and phototrophic picoeukaryotes and a variety of indicator pigments for dinoflagellates, diatoms, green algae and cryptophytes also showed similar spatial distribution patterns, suggesting that phytoplankton assemblages respond to the environmental gradient by changing community compositions. In addition, primary production and bacterial production were also highest in the bay surrounded by mangrove forest and lowest outside of the lagoon. These results suggest that mangrove waters play an important role in energy production and nutrient cycling in tropical coasts, undoubtedly receiving large inputs of organic matter from shore vegetation such as mangroves. However, the steep decrease of biomass and production of phytoplankton and heterotrophic bacteria within a short distance from the bay to the level of oligotrophic waters indicates that the effect of mangrove waters does not extend far away.