• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.489-494
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• 2010

The nutritional demand of oyster larva (Crassostrea gigas) were investigated to determine the optimal culture conditions and improve micro-algae utilization. Changes in nutrients and shell growth were examined in fed and 96-h (48 h in late umbone stage) oysters at four larval stages. Shell growth increased significantly in D shape larvae, regardless of feeding variations. No growth was observed in starved larvae, except in shell length of umbone (to 11.9 ${\mu}m$). Fed larvae showed significant growth in all development stages (P < 0.05). During starvation, lipids were most significantly decreased in all larval stages (by 76.8%, 68.3%, 76.3%, and 40.3%, respectively), followed by protein (41.1%, 31.1%, 33.1%, 16.7%) and nitrogen-free extracts (40.8%, 24.3%, 36.9%, 20.1%), Gross energy (kcal/g) consumption in each larval stage was 49.6%, 35.1%, 39.1%, and 20.4%, respectively. Our results indicate that lipids are the most important energy source during the early larval development stages of C. gigas.

• Journal of Aquaculture
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• v.16 no.3
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• pp.196-201
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• 2003

Sessile organisms such as the oyster Crassostrea gigas have been given much attention as a potential biomonitoring indicator to assess the impact of toxicants on aquatic organism. In this study, we exposed cells isolated from gill of oyster (Crassostrea gigas) to hydrogen peroxide in vitro. In addition oysters were in vivo exposed to pyrene and benzo(a)pyrene at various concentrations for 2 weeks. Comet assay was used to detect DNA single strand breaks and to investigate the application of this technique as a tool for aquatic biomonitoring. Hydrogen peroxide increased DNA single strand break with increasing concentration after 30 minutes exposure in vitro. Pyrene and benzo(a)pyrene caused DNA damage only at very high concentration (100 $\mu\textrm{g}$/L or 1000 $\mu\textrm{g}$/L) at two week exposure in vivo. DNA damage was relatively higher at hemocyte than at gill. It suggested that metabolized PAHs are transferred to hemolymph from digestive gland which have a relatively high enzyme activity, and attacked the DNA of hemocyte, while gill accumulated PAHs without degrading them to their metabolites due to low enzyme activity at gill. Both in vitro and in vivo exposure experiments showed that the comet assay is an effective tool on screening whether the organism are exposed to genotoxic contaminants.

• The Korean Journal of Malacology
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• v.31 no.1
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• pp.43-48
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• 2015

Oxygen isotope ratios (${\delta}^{18}O$) of three Pacific oyster (Crassostrea gigas) specimens from the Neolithic Yeondae-do shell midden site, Tongyeong, Korea, were analyzed to determine the seasonality of shellfish gathering and site occupation. Oxygen isotope samples were taken from the left valve hinge sections of the specimens. Oxygen isotope values ranged between -0.1 ‰ and -2.4 ‰, between -0.2 ‰ and -2.9 ‰, and between 0.3 ‰ and -2.8 ‰ in oyster specimen #one, #two and #three, respectively. The isotope profiles showed seasonal temperature cycles, providing information related to the seasonality of shellfish gathering and site occupation. Hinge-edge oxygen isotope values of the specimens showed decreasing trends after passing through maximum values (winter), indicating that they formed during spring. Thus it can be assumed that during spring season, oysters were gathered and the site was occupied.

• Ocean and Polar Research
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• v.32 no.3
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• pp.237-245
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• 2010

Bioaccumulation of polychlorinated biphenyls (PCBs) and organochlorine pesticides was studied in sediment dwelling bivalves, Manila clams (Ruditapes philippinarum), collected from the midwestern coast of Korea. As witnessed by the dominance of tetra- to penta-chlorinated congeners in sediments and the penta- to hexa-chlorinated congener dominance in clams, the profile of PCBs in the sediments and Manila clams differed. Lipid and organic carbon-normalized biota-sediment accumulation factors (BSAFs) were determined for organochlorine pesticides. BSAFs of $\beta$-hexachlorocyclohexane ($\beta$-HCH) and $\Sigma$DDTs were in the range of 0.06~1.36 and 0.31~1.06. No clear relationships were found between BSAFs of $\Sigma$DDTs in Manila clams and the concentrations of DDTs in the associated sediment. The accumulated PCBs and organochlorine pesticides were compared in Manila clams and oysters (Crassostrea gigas) collected from 3 sites. Highly chlorinated PCBs were more commonly found in oyster tissues than in clam tissues. The reasons for the different accumulation pattern of organic pollutants in the two organisms are discussed.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.154-162
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• 2022

In this study, data on the types and density of abalone attached organisms were provided in marine net cage of the southern coast. In addition, the effect of the removal of attached organisms was evaluated. In marine net cage, oysters, bryozoa, and barnacles were dominated among the attached organisms, and their average area ratio was about 57.5%. The growth rate and hepatopancreas condition were better in removal group of attached organisms than control group. Therefore, it is judged that the removal of attached organisms from abalone is necessary for the growth of individuals and improvement of value.

• The Journal of Fisheries Business Administration
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• v.53 no.4
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• pp.069-078
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• 2022

This study studied the characteristics of cultured oyster marketing in Sacheon Bay. The results of this study are summarized as follows. First, the GULDAE aquaculture is a unique production method of Sacheon Bay. Second, oysters in Sacheon Bay were low in production, but the price was more than 70% higher than in other producing areas. Third, profit is 12.5% higher and rate of return was 179.8%. Fourth, there were more out-of-market sales than other than other producing areas, and it is a bidding method. Fifth, the marketing cost was higher than the longline hanging aquaculture; however, the advantage of price offseted this point. Although the Sacheon Bay Oyster aquaculture is small, it was confirmed that it was a producing area with high profitability and a unique marketing form from other regions. Although the Sacheon Bay Oyster culture is small, it has been confirmed that it is a producing area with high profitability and shows a unique distribution form.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.2
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• pp.122-128
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• 2024

We investigated the quality of 10 commercial eorigul-jeot, salt-fermented oysters with seasoning, by measuring their chemical composition and bacterial concentrations. The Eorigul-jeot had 5.07-6.06 pH (mean, 5.63), of 1.92-4.74% salinity (mean, 3.36%), 7.01-14.70 mg/100 g volatile basic nitrogen (mean, 11.91 mg/100 g), 139.22-267.11 mg/100 g amino acid nitrogen (mean, 212.69 mg/100 g), and 1.02-1.65 g/100 g total acidity (mean, 1.24 g/100 g). The total viable and lactic acid bacterial counts were 5.7×10⁴-8.7×10⁵ and 2.7×10³-2.0×10⁵ CFU/g, respectively, and fecal coliform was detected in only one Eorigul-jeot sample. Bacillus cereus and Clostridium perfringens were detected in two samples, and all Eorigul-jeot samples were negative for Staphylococcus aureus and Vibrio parahaemolyticus. These results strongly suggest the need to monitor food-poisoning bacteria in commercial Eorigul-jeot to ensure consumer health.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.1-6
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• 2016

In this year, Koreans have a shortage in agricultural and drinking water due to severe algal blooms generated in major lakes. Waste oyster shells were obtained from temporary storage near the workplace at which oysters were separated from their shells. Heating ($1000^{\circ}C$ for 1 h in air) was employed to convert raw oyster shell powders into calcium oxide powders that reacted efficiently with phosphorus and nitrogen to remove algal blooms from eutrophicated wastewater. As the dispersed amount of heated oyster shell powders was increased, water clarity and visual light penetration were improved. Coagulation, precipitation and carbonation process of the heated oyster shell powders in a water purifier facilitated removal of eutrophication nutrient such as phosphorus and nitrogen, which is both beneficial and economically viable. $CO_2$ implantation by carbonation treatment not only produced thermodynamically stable CaO in oyster shells to derive precipitated calcium carbonate (PCC) but also accelerated algal removal by activation of coagulation and precipitation process. The use of oyster shell powders led to a mean reduction of 97% in total phosphate (T-P), a mean reduction of 91% in total nitrogen (T-N) and a maximum reduction of 51% in chemical oxygen demand (COD), compared with the total pollutant load of raw algal solution. Remarkable water quality improvement of algal removal by heated oyster shell powders and PCC carbonation treatment will allow utilization as water resources to agricultural or industrial use.

• Korean Journal of Community Nutrition
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• v.14 no.4
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• pp.392-405
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• 2009

This study was conducted to investigate food and meal preference of workers (435 male and 212 female) in the Chonnam Yeosu industrial area. The results of the survey were analyzed by principal components analysis. The results were obtained as follows: 19.3% of the subjects were twenties, 28.3% were thirties, 28.8% were forties and 23.7% were fifties. Females liked rice rolled in dried laver, rice cakes, janchi-noodle and breads, on the other hand males liked thick beef soup, loach soup, an eel stew and soju. The young liked instant noodles, fried chicken, sweet and sour pork, pork cutlet, pizza, hamburger, ham, sausage and fruit beverage, on the other hand the old liked a fish pot stew, loach soup, eel stew, fish boiled in soy with spices, panfried fish, sea slug, ascidian, bunder, green laver and boiled burdock-lotus root in soy. Females who are young liked hamburger and sweet and sour pork whereas males who are young liked instant noodles, pork cutlet, ham, sausage and fruit beverage. Aged females liked fish boiled in soy with spices, panfried fish, bunder, green laver, boiled burdock-lotus root in soy whereas aged males liked a fish pot stew, loach soup, eel stew, sea mussel and oysters. Boiled rice was located within the middle irrespective of age and sex, but noodles, wheat flour meal, fast foods and fruits were situated at the young female side. Aged males liked soup and pot stew. Young males liked meats and eggs whereas fish and shellfish and kimch were located at the aged people side. Aged females liked sea weeds and most people disliked vegetables but females liked some vegetables irrespective of age. Processed foods, salted foods, and alcohol were generally disliked foods by subjects but males liked those foods. Soybean curd was liked more males than females, and teas, except coffee, was liked by males. (Korean J Community Nutrition 14(4) : 392${\sim}$405, 2009)

• Parasites, Hosts and Diseases
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• v.39 no.2
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• pp.85-118
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• 2001

Studies on Gymnophalloides seoi (Digenea: Gymnophallidae) and human infections are briefly reviewed. This minute intestinal fluke was first discovered from a Korean woman suffering from acute pancreatitis and gastrointestinal troubles. It was described as a new species by Lee, Chai and Hong in 1993. The southwestern coastal village where the patient resided was found to be a highly endemic area, and additional endemic areas have been identified. The parasite is very small, 0.33-0.50 mm long and 0.23-0.33 mm wide. and characterized by the presence of a ventral pit. The first intermediate host remains unknown, but the second intermediate host has been found to be the oyster Crassostrea gigas. Man and the Palearctic oystercatcher Haematopus ostralegus have been shown to be natural definitive hosts , and wading birds including the Dentish plover Charadrius alexandrinus are highly susceptible to experimental infection. Gerbils, hamsters, cats, and several strains of mice were also susceptible laboratory hosts. In experimentally infected mice, the parasites inhabit the small intestine, pinching and sucking the root of villi with their large oral suckers, but they did not invade beyond the mucosa in immunocompetent mice. However, they were found to invade the submucosa in immunosuppressed mice. Human G. seoi infections have been found in at least 25 localities; 23 islands on the Yellow Sea or the South Sea, and 2 western coastal villages. The highest Prevalence was found in a village on Aphaedo. Shinan-fun (49% e99 Positive rate) : other areas showed 0.8-25.3% prevalence. Infected people complained of variable degrees of gastrointestinal troubles and indigestion. The infection can be diagnosed by recovery of eggs in the feces; however, an expert is needed to identify the eggs. Praziquantel, 10mg/kg in single dose, is effective for treatment of human infections. Eating raw oysters in endemic areas should be avoided.