• Fisheries and Aquatic Sciences
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• v.26 no.5
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• pp.355-365
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• 2023

The Pacific abalone, Haliotis discus hannai, is a highly valued and industrially important aquaculture species with growing demands of the expanding abalone aquaculture industry. To explore the feasibility of using the brown alga, Sargassum horneri, as a potential substitute for abalone feed, it is important to identify the feed preference and attractant effect of S. horneri on Pacific abalone. Our experiments indicated that the feeding-associated movement of abalone could be detected using a video tracking system under indirect illumination with dim red light. To further analyze the attraction potentials of various test materials, preference analysis was performed using Avicel-coated glass plates with ground powders of various seaweeds (e.g., S. horneri, Saccharina japonica, and Undaria pinnatifida) and commercial abalone feed, together with coffee waste. Heat map analysis indicated greater attraction by the kelp S. japonica than by S. horneri and commercial feed, which showed similar preference levels. Feeding preference based on the area of Avicel eaten by abalone showed a significant preference for U. pinnatifida over S. horneri (feeding area: 68.6 ± 20.1% vs. 37.5 ± 22.4%, p < 0.05). Additionally, the feeding area was significantly greater for plates with S. japonica than for plates with S. horneri (44.0 ± 16.6% vs. 22.6 ± 15.4%, p < 0.05). There was no significant difference in feeding area between commercial feed and S. horneri (31.7 ± 11.6% vs. 31.6 ± 20.2%, p > 0.05). The methanol extracts attracted abalone in the following order: U. pinnatifida > S. horneri > S. japonica > commercial feed > coffee waste. To determine the attractive effects of the components of methanol extracts, mixtures of methanol extracts of commercial feed with increasing amounts of S. horneri were examined. The results showed a significant increase in feeding preference upon addition of S. horneri up to 50% and 75%, suggesting its potential for use as an appetite-enhancing feed additive. This study identified conditions that can be successfully used to monitor the movement of Pacific abalone; the results of preference analysis confirmed that abalone exhibited similar attraction and feeding preference for S. horneri, compared with commercial feed.

• Journal of Microbiology and Biotechnology
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• v.34 no.8
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• pp.1705-1710
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• 2024

Plastic waste has emerged as a major environmental concern in recent years. As plastic waste discharged into the marine environment, it undergoes a breakdown process, eventually accumulating in aquatic organisms in the form of microplastics (MPs). To date, reduced food intake, nutritional absorption, and impaired immune system are known adverse effects of MPs-exposed aquatic organisms. This study aims to investigate whether MP exposure accelerated white spot syndrome virus (WSSV) infection in Pacific white shrimp (Penaeus vannamei) via laboratory tests. Briefly, experimental shrimp were divided into four groups; WSSV (group 1); MP (group 2); WSSV + MP (group 3); and Control (group 4). No mortality was observed in group 2, group 4, and even in group 1. However, group 3 showed a cumulative mortality of 50% during the experimental period. The PCR assay results showed no WSSV in the other three groups (groups 1, 2, and 4), but the dead and alive shrimp collected from group 3 were confirmed to be infected with the virus. Histopathological examination revealed normal structures in the hepatopancreas, gill, and muscle tissues of group 4, whereas numerous abnormally shaped nuclei were detected in the gill tissue of group 2. Moreover, group 1 showed minor WSSV-related lesions with few basophilic inclusion bodies in the gills, interestingly, group 3 exhibited severe lesions with numerous basophilic inclusion bodies in the gills. In conclusion, this study confirmed the correlation between the viral disease of shrimp and MPs, which can cause significant economic losses to the shrimp aquaculture industry.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1947-1953
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• 2006

There have been a number of studies of methods for recycling animal wastewater to provide new bioresources. In the present work, a marine algal culture medium, designated KEP II, was prepared by adding swine waste (3% v/v) fermented by soil bacteria to a dilution of f/2 culture medium (CT). When Phaeodactylum tricornutum was grown in batch culture in KEP II, the cells lasted long at the exponential phase producing the specific growth rate and biomass; the production of total amino acids and secondary metabolites rose up to 5-fold. It also substantially enhanced the maximum quantum yield of photo system (PS) II of P. tricornutum, greatly increased the level of thylakoid membranes containing PS, and stimulated the production of pyrenoids, including enzymes for $CO_2$ fixation in chloroplasts. KEP II should improve the cost efficiency of industrial mass batch cultures and the value of microalgae for long-term preservation of fresh aquaculture feed as well as production of anticancer and antioxidant agents. Specifically, a low-cost medium for growing the diatoms of aquaculture feed will be economically advantageous.

• The Journal of Fisheries Business Administration
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• v.51 no.2
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• pp.71-87
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• 2020

Oysters are the most abundantly harvested type of shellfish in Korea. As export of this marine product increases, oysters have greatly contributed to an increase in fishing income. As the oyster aquaculture industry has rapidly grown since the late 1990s, issues of oyster-shell processing that occur in production processes have re-emerged as important topics in the oyster industry. The amount of oyster shells harvested in 2019 is estimated to be approximately 300,000 tons. With reductions in demand for pyrolytic fertilizer and feed, which are currently the greatest sources of demand, unprocessed shell quantities have doubled compared to 2018, causing them to be an issue once more. Such oyster-shell processing also incurs great costs, and a total of forty-six billion three hundred fifty million Korean won (46,350,000,000 KRW) has been provided from 2009 to 2020 for the use of oyster shells as a resource. According to current Korean laws, oyster shells are considered to be industrial waste if more than 300 kilograms are sent out in a day. Collection and processing must be conducted by a waste-consignment company. Consequently, there are many limitations to the use of oyster shells in Korea as a resource. However, in Japan, only oyster-shell waste is regulated by waste-processing As a result, local governments may apply exceptions when utilized as organic matter. Consequently, in Japan, oyster shells are being used as resources in more diverse fields than in Korea. This study observes the conditions and problems of oyster-shell processing in Korea and attempts to find new domestic oyster-shell resource solutions in light of Japan's recycling practices.

• Journal of Aquaculture
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• v.16 no.2
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• pp.104-109
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• 2003

The present study aims to evaluate protein and phosphorus availabilities of five different dietary protein sources during the 6-week feeding trial in juvenile olive flounder, Paralichthys olivaceus as determined by growth performance and phosphorus retention. Five diets containing blood meal (BM), poultry by-product (PBP), squid liver powder (SLP), feather meal (FM) and soybean meal (SM) were prepared by mixing a basal diet (BD) with one of five test ingredients at the ratio of 7 to 3. As a reference diet, BD contains three different protein sources such as white fish meal, casein and gelatin. After 2 weeks of the conditioning period, fish initially averaging 2.7$\pm$0.02g (mean$\pm$SD) were randomly distributed into each aquarium as a group of 30 fish reared in the recirculating system. Fish of triplicate groups were fed one of six experimental diets (BD+five test diet). After 6-week feeding trial, pro- tein efficency ratio (PER) of fish fed BM diet was the lowest in experiment groups. While fish fed PBP diet showed a significant higher PER as compared to the FM diet, and fish fed SLP diet and BD were a higher PER than did fish fed PBP diet. However, there was no significant difference in PER among fish fed SLP diet, BD and SM diet, and between SM diet and PBP diet. Phosphorus retention efficiency of bone (PR $E_{b}$) of fish fed BM diet was the lowest in all the diets, and fish fed FM diet showed a higher PE $R_{b}$ than fish fed BD and SM diet. However, there was no significant difference in PER among fish fed FM diet, SLP diet and PBP diet, and among SLP diet, PBP diet, SM diet and BD. These results indicate that SLP could be a suitable protein source for low pollution diets of olive flounder in the future fish feeds market. Furthermore, PBP and SM are available protein source to reduce P waste in the oliver flounder aquaculture with the use of proper mixture of other protein sources and more processing to improve protein availibility of these.ese.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.5
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• pp.125-134
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• 2018

Recently, interest in alternative energy has been increasing to reduce greenhouse gas emissions and fossil fuel consumption in accordance with the United Nations Framework Convention on Climate Change(UNFCCC). Accordingly, there is a need to use waste heat that unused throughout industrial systems for lowering the concentration of energy on fossil fuels. In particular, government support projects for the energy recycling of agriculture and fisheries such as cultivation of tropical crops and aquaculture are being actively carried out by utilizing waste heat and thermal effluents caused from large-scale industrial complexes including power plants. The study was conducted on supplier (power plant), consumer (farmer) and stakeholders (constructor and local governments) of domestic demonstration areas using waste heat that is abandoned from the power plant in the form of thermal effluents. It investigated the overall improvement and feasibility of government funded projects through field interviews and questionnaire-type surveys. The results of this study are expected to provide basic directions for the operation of the project in terms of nationwide expansion and diffusion of the heat source supply project at horticultural greenhouse by utilizing the thermal effluents from power plant.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.3 no.1
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• pp.23-31
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• 1999

An advanced mobile technology is described for saturating water with oxygen. The MTR(Mass Transfer Reactor) is 2~10 times more effective in dissolving oxygen in water compared to most other systems used in aquaculture, because it can generate extremely small(0.005~0.05mm) bubbles. New fish farming facilities could make use of this technology to build deeper ponds for raising multiple species with optimized conditions for DO(dissolved oxygen), food, light, etc. The proposed technology offers higher DO levels with minimal operating costs. It is easy to use and maintain, with a high reproducibility. Accordingly, the MTR can be industrially applied in the treatment of fish waste and reduction of water consumption during fish farming.

• Journal of the Korean Institute of Landscape Architecture
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• v.23 no.2
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• pp.167-181
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• 1995

An Ecocomplex is proposed for ecological design of the estuarine environment of Han River, which is designed upon an alternative mamagement concept of estuarine environment. The concept reveals interrelationships among estuary, delta region and urban inland with inputs/outputs and feedbacks among them. The Ecocomplex emphasizes an integration of wastewater treatment with aquaculture, agriculture and recreation, and carries out ecological treatment, recycling, and harvest processes. A module of wastewater treatment pond system is employed in the Ecocomplex, which treats a flow of 3,786 ㎥/day and is composed of a four-facultative-pond series. Treatment ponds stabilize wastewater discharged from the urban area, and concurrently produce algae for commercial or recreational fish farming. Effluent from treatment and fish ponds is reused for agricultural production. Through the waste-algae-fish-vegetable-recreation processes, wastewater from the urban settlement is recycled back to the urban ecosystem. This resource-conserving design approach can maintain a sustainable urban ecosystem, managing an estuarine environment more naturally, healthly, and economically.

• Korean Journal of Environmental Agriculture
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• v.19 no.4
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• pp.339-344
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• 2000

Utilization of animal excreta in aquaculture can have potentials of high fish production and low maintenance costs for fish farming and it can reduce water pollution caused by animal waste disposal. Integration of wastewater treatment pond system with aquaculture has been utilized in many countries. Ecologically balanced pond ecosystem is formed through the stabilization of wastes, the growth of aquatic plants, and the cultivation of fish. The most appropriate fish for rearing in these ponds are those which can feed directly on phytoplankton, especially algae. Carp were introduced into a tertiary pond - water depth of 2.2 m, water surface area of $130\;m^2$, volume of $148\;m^3$ - of a pond system treating milk cow excreta. The carp production was $125g{\cdot}m^{-2}year^{-1}$ which falls into upper range of $18\;-\;137g{\cdot}m^{-2}year^{-1}$ of treated sewage-fed carp farming of other countries. Average $BOD_5$ and T-N of the pond was 19.8 and $21.0\;mg{\cdot}L^{-1}$ respectively, and the ecological environment of it was suitable for growth of carp. Several carp of 100g were introduced in August into a secondary pond of the treatment system, whose average $BOD_5$ and T-N was 27.9 and $30.8\;mg{\cdot}L^{-1}$ respectively. They were died within one week, which may be attributed to the depletion of dissolved oxygen at dawn. Effluents from primary treatment can be used in fish pond with dilution and those from secondary treatment can be directly funnelled into it. Waste stabilization pond treating animal excreta can be utilized for fish rearing when its water quality maintains secondary treatment level.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.3
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• pp.254-262
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• 2003

Effect of the air distributor pore size for the removal of aquacultural waste, such as protein, total suspended solids (TSS), chemical oxygen demand (COD), turbidity and total ammonia nitrogen (TAN) from sea water was investigated by using foam separator. With the increase of pore size of air distributor, removal rates and efficiency of protein decreased. Removal rate by commercial air stone was in the range between the removal rates by G2 and G4 sintered glass discs. Within the range of pore size distributor from Gl to G4, the removal efficiency of protein were ranged from 21 to $42\%.$ The changes of removal rates and efficiencies of TSS, COD and turbidity were similar to proteins. TAN was removed by stripping. The pore size of air distributor for a higher overall oxygen mass transfer coefficient and saturation efficiency provided the condition for higher protein removal rate. Also the foam separator could be used as an aerator.