• Journal of fish pathology
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• v.14 no.2
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• pp.65-70
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• 2001

The purpose of this study is to find out the effects of various bis(tri-n-butyltin)oxide (TBTO) on changes of inorganic matter and enzyme activity in the hemolymph of Pacific Oyster, Crassostrea gigas. Oyster were exposed to 5, 10, 20, 50, 80and $100{\mu}g$/L of TBTO for 20 days. Survival rate of the oyster wass significantly affected by $\geq80{\mu}g$/L TBTO concentration at 10 days, while the diminution of survival was found at 20 days with a lower concentration of $\geq50{\mu}g$/L TBTO. Calcium concentration in the hemolymph increased significantly after 20 days at the TBTO concentration $20{\mu}g$/L. However no change of magnesium and inorganic phosphate in the hemolymph was showed. A significant increment of GOT activities in the hemolymph was observed after 20 days at more than $20{\mu}g$/L TBTO concentraion, without typical changes of GPT activities. These results indicate that oysters can be affected by TBTO in terms of calcium concentration and GOT activity in the hemolymph when they were exposed to the TBTO concentration $20{\mu}g$/L.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.1
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• pp.27-33
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• 1979

In early August 1978, a huge red tide occurred off Chilcheon Is, , at the mouth of Jinhae Bay. It expanded rapidly into the central part and then soon covered all the bay except the innermost part of the bay. After staying for a week it disappeared, and thereafter several small scale red tides partially occurred and disappeared untill the end of August. It differed from the red tides hitherto recorded from this bay in respect of the dominant plankter, the geographical extent and the severe damaging effect to local oyster resources. During the red tide period, nevertheless, no oyster damage was found. In September, however, oyster mortailty was found from all rafts and longlines in the bay. Except the inner most part of the bay the oyster farms were completely destroyed. Of the oyster Production in the winter 1978, $96\%$ of an estimated yield of 5,879 tons (shucked meat) was lost and it was estimated to be 2,275 million won, equivalent to $US\$$ 4.55 million. The dominant species was a dinoflagellate, Ceratium fusus and it constituted about $45\%$ of the total phytoplankton. Cell count showed $7.0\times10^4\;cells/\iota$ and chlorophyll-a, $50mg/m^3$ during red tide peak. No oxygen was found ill the bottom waters in September. Sulphides in bottom waters and in the superficial mud increased to 15 and 8-fold respectively in September compared with July ana August. Precipitation from January to May of 1978 was about a third in comparison with the past ten years average but rainfall ill June was two and half-fold more than normal year, and thereafter drought persisited till September Air and water temperatures were also higher, and sunny days continued for a long time without strong winds. Therefore, water was calm for a long time after the red tide extinguished. The result indicated that the occurrence of the Ceratium red tide occurred in that year which was characterized by the combination of the formation of almost anoxic bottom water before the red tide occurrence, high air temperature and the calmness after a great quantity of rainfall in June. The mass mortality of oysters was presumed not to be directly related with the red tide but with the depression of dissolved oxygen in the environmental waters at the bottom due to settling of the red tide organisms.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.1
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• pp.54-62
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• 2010

With the aim of developing and indoor overwintering technique for Pearl oyster, Pinctada fucata martensii, the metabolic rates of young oysters (52.4-83.0 mm in shell length) were measured for 2 weeks at water temperatures of 8, 10, 12, and $14^{\circ}C$. The filtration rate (FR) ranged 0 to $4.84\;L\;h^{-1}gDW^{-1}$ (mean, $0.02{\pm}0.06 $ to $3.12{\pm}1.45$), with significant changes observed over thme except for the case of a water temperature of $14^{\circ}C$. Respiration rate (R) ranged from 0 to $2.370\;mgO2\;h^{-1}gDW^{-1}$ (mean, 0 to $1.77{\pm}0.37$), with significant respiratory disorders observed at temperatures below $12^{\circ}C$; in contrast, the rate increased on the $14^th$ day of the experiment in the case of a temperature of 14$^{\circ}C$. No significant difference was observed among the different water temperatures in terms of excretion rate (E) or absorption efficiency (Abs.eff), except for a significant decrease in aerobic metabolism in the case of water temperature of $8^{\circ}C$. The estimated scope for growth (SFG) ranged from -9.1 to $126.9\;J\;h^{-1}gDW^{-1}$ (mean. $-4.1{\pm}2.6$ to $82.85{\pm}42.6$). A significant energy Joss was found at $8^{\circ}C$, with negative SFG observed throughout the experiment and a gradual energy decrease observed over time at water temperatures of $10^{\circ}C$ and 120C. However. SFG remained positive throughout the experiment in the case of $14^{\circ}C$. The estimated minimum energy requirement, assessed from energy expenditure, is $8.00-34.24\;J\;h^{-1}gDW^{-1}$ (mean, $17.67{\pm}6.17$). In conclusion, the lowest temperature suitable for indoor overwintering is above $14^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.5
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• pp.589-598
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• 1995

Filtering rates of Crassostrea gigas were experimentally investigated with reference to effects of water temperature and size. Absorptiometric determinations of filtering rates with oysters being fed diatom Chaetoceros calcirtans were carried out in a closed system. Optical density of 675nm in path length 100mm cell used as the indication of food particles absorption was appeared directly In proportion with the concentration of diatom pigment $chlorophyll-\alpha$. In the closed system where $C_0$ is $OD_{675}$ at initial time 0, $C_t$, at time t, and Z is the decreasing coefficient of OD as meaning of instantaneous removal speed, then $C_t=C_0{\cdot} e^{-2t}$, $Z=In(C_t/C_0)/t$. On the assumption that the filtering rate is constant, then removal rate per unit time (d) is $d=-e^{-z}$. If t is used to time unit of hour (hr), the filtering rate (FR) in I/hr is given by $FR=V{\cdot}d=V(1-e^{-z})$, where V is the water volume (I) of the experimental vessel. Filtering rate increased as exponential function with increasing temperature while not over critical limit. The critical temperature for filtering rate was assumed to be between $28^{\circ}C$ and $29^{\circ}C$. And the weight exponent for filtering rate is 0.223. The model formula derived from the results as FR, $Ihr^{-1}$ = $Exp(0.208{\cdot}T-4.324){\cdot} (DW)^{0.223}$ (T<29 $^{\circ}C)$ where T is water temperature $(^{\circ}C

• Journal of Fisheries and Marine Sciences Education
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• v.18 no.2
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• pp.164-171
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• 2006

kochukaru (chili powder) and various vegetables. As its main ingredient, fresh or sea-water fish is cut into several pieces and boiled with ground beef and green vegetables such as watercress as well as garland chrysanthemum. In addition, onion, radish, chilies, crown daisy, garlic and some times, pumpkin and bean curds are added to the mixture to absorb the kochujang which is the base flavor of this dish. It is then seasoned with kochukaru, garlic, soy sauce and if needed, more kochujang to suit everyone's taste buds. Restaurants that offer this dish often allow you to select your fish from a tank. Many specialty seafood restaurants have several tanks from which you may choose a fish. Popular fish for this dish may include Korean rockfish, flounder, yellow corvina, codfish, croakers, pollacks, and even fresh water fish like carp and trout. In addition, other shell fish such as crabs, clams and oysters can be also added to this soup to compliment and enhance its spicy but refreshing flavor. This soup is one of Korean's most popular dishes while drinking soju. If you order sushi or sashimi, the soup is made from the left-over parts of the fish. The objective of this study is to determine a standardized recipe of Maeun-Tang and to investigate consumption so as to increase its intake opportunities for consumers through its development. Fish species used in Maeuen-Tang's recipes were flounder, Korean rockfish and other fish. Onion, radish, chilies, crown daisy, garlic and some times, pumpkin and bean curds were added to the mixture to absorb the kochujang which is the base flavor of this dish. Most of the stock used in Maeuen-Tang's recipes is pure water, fish stock and vegetable stock, 1.0-1.5 Korean rock fishes and 0.5-1.0 flounders, with its head and bone, which were used in 3-4 portions of Maeun-Tang. Most of the seafood restaurants used seasoning which didn't age and was made by the restaurant. The cooking equipment used in the Maeuen-Tang's recipes were a cook-port and earthen bowl.

• Ocean and Polar Research
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• v.34 no.2
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• pp.137-149
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• 2012

Hemocyte parameters of the wild Pacific oyster Crassostrea gigas inhabiting intertidal zones in small bays (Gwangyang and Jinhae Bay) on the southern coast of Korea were evaluated using flow cytometry and neutral red retention (NRR) assay. Morphological features, cell count, mortality, DNA damage, phagocytosis, and lysosomal membrane stability of hemocytes were analyzed. Three types of hemocytes were identified in the oyster hemolymph: granulocytes, hyalinocytes, and blast-like cells. Immune related functions of hemocyte including phagocytosis and lysosomal membrane stability were significantly different among the study areas (P<0.05), while cell count, mortality, and DNA damage of hemocytes were not significantly different. In Gwangyang Bay, phagocytosis of granulocytes and lysosomal membrane stability of oyster hemocytes inhabiting inside bay were significantly lower than those of oyster hemocytes in outside bay (P<0.05), indicating that oysters in inside bay of Gwangyang were relatively suppressed the immunological function in hemocytes. Contrary to Gwangyang Bay, immune parameters of oyster hemocytes in Jinhae Bay not showed the difference between sampling sites. In conclusion, flow cytometry and NRR assay using oyster hemocyte has a powerful tool to investigate the cell level in a short time due to no-preprocessing of material.

• Ocean and Polar Research
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• v.36 no.2
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• pp.121-134
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• 2014

Sessile marine bivalves including mussels, oysters and clams are often used as a sentinel species in coastal environmental monitoring since changes in the environmental quality are often well preserved in their tissues and shells. In this study, we investigated overall health condition of the Mediterranean Mussel, Mytilus galloprovincialis on the south coast using histology. Reproductive condition as gonad index (GI), condition index (CI) as a ratio of the tissue weight to the shell weight, digestive gland atrophy (DGA), types of parasites, and pathologic conditions including erosion, necrosis, hemocyte infiltration, and neoplasia were examined from each histological preparation. GI decreased from March to July then increased from July to September and spawning mussel could be observed as early as in April and the activity continued until September. CI also followed the monthly changes in GI, indicating that decrease in CI was associated with the weight loss due to spawning. DGA increased from March to June, decreased in July and increased from July to September. High DGA values observed in June and September were coincided with spawning and high water temperature. Histology also showed high prevalence of erosion in the digestive gland in June (36.0%) and September (56.4%), suggesting that high water temperature and spawning acted as environmental stressors. No parasitic organism was identified during the survey, although some symbiotic copepods were observed. Histology was found to be useful and affordable technique in monitoring the overall health of mussel, providing useful pathologic information of the cells and tissues.

• Parasites, Hosts and Diseases
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• v.35 no.1
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• pp.25-30
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• 1997

Gymnophclloides seoi is a human intestinal trematode prevalent on southwestern islands in Korea. In the present study, we investigated whether G. seoi metacercariae can grow and develop into adults by in vitro cultivation. The metacercariae were obtained from naturally infected oysters, and cultured in uitro for 5 days under three conditions; $37^{\circ}C/5%{\;}CO_2,{\;}41^{\circ}C/8%{\;}CO_2,{\;}or{\;}41^{\circ}C/15%{\;}CO_2$, in NCTC 109 complete media containing 20% FBS and 1% antibiotics-antimycotics. The degree of worm growth and development was compared with that grown in uiuo of C3H mice. The length of the worms cultivated in uitro was $200-300{\;}\mu\textrm{m}$, not significantly different from metacercariae, whereas the length of the worms recovered from C3H mice was significantly larger, $300-400{\;}\mu\textrm{m}$. The worms produced eggs when grown in C3H mice or cultured in vitro for 2 days under $41^{\circ}C/8%{\;}CO_2{\;}or{\;}41^{\circ}C/5%{\;}CO_2$, but not when cultured under 37$^{\circ}C/5%{\;}CO_2$. Among the in vitro conditions, $41^{\circ}C/15%{\;}CO_2$ was best for egg Production, although the number of eggs was about half of worms obtained from C3H mice. In conclusion, in vitro cultivation of G. semi metacercariae into egg-pioducing adults was partially successful under culture conditions of $41^{\circ}C/5%{\;}CO_2{\;}or{\;}41^{\circ}C/8%{\;}CO_2$.

• Journal of Conservation Science
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• v.34 no.5
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• pp.397-405
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• 2018

Currently, there are very few studies on Korean wall paintings. Therefore, this study discusses the current conditions of wooden paintings and the characteristics of the adhesive agent in the painting layer separation. Korean land pine was chosen as the support, while white oysters shells, orpiment, red ocher, Noerok, and azurite were used as pigments. With four adhesive agents, including animal glue, Gelidium, methyl cellulose, and PVAc (caparol binder), a comparative experiment was conducted, by dividing them into two concentrations, of 0.5% and 1.5%. The temperature, humidity, and ultraviolet rays, which are contributing environmental factors in cultural assets after fixing, were artificially investigated. After deterioration, observed color difference, fixing, and the surface. Results showed that the animal glue strongly fixing all the colored layers compared to the other adhesives; however, azurite had a partial change when used outdoors. With Gelidium, which functioned similar to animal glue, the azurite was affected by the ultraviolet rays; nevertheless, despite the variations in temperature and humidity, it had the best gripping force compared to the other adhesive agents. Methyl cellulose was glossy at a high concentration, and was relatively strong against rapid changes in temperature and humidity. PVAc significantly reduced the binding force, compared to other adhesive agents.

• Journal of fish pathology
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• v.28 no.1
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• pp.27-35
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• 2015

VHSV is a major viral agent that affects freshwater and marine fish, causing serious economic losses in aquaculture in the world. Due to their filter-feeding activity, bivalve mollusks may act as viral transmitters after accumulation of the fish viruses released into seawater from infected fish. Amplification by RT-PCR was carried out to investigate the presence of VHSV in pacific oysters (Crassotrea gigas) and blue mussels (Mytilus edulis), inhabiting regions around aquatic farms in Korea. Primers designed from conserved regions of VHSVs allowed us to detect four different types of VHSV in a single PCR. Twenty two of the eighty four samples showed positive results of VHSV in a 2-step RT-PCR. Using six positive samples from three different regions in Korea, we cloned and sequenced the glycoprotein (G) gene (467-bp long) of VHSVs. Genetic analysis of the VHSVs detected in shellfish in various geographical areas of Korea showed highly restricted results to VHSV type Iva. This was in agreement with the reports showing only a single genotype of VHSV (Iva genotype) in outbreaks in cultured or wild fish in Korea. Consequently, we investigated VHSVs carried by bivalve mollusks inhabiting the vicinity of aquatic farms, and revealed correlationship between the type of viral accumulated in shellfish by filter-feeding, and those detected in disease outbreaks in fish.