• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.842-846
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• 2016

It's possible for a human to breathe under water, but the amount of dissolved oxygen in the water is small and a large amount of water is necessary to obtain sufficient dissolved oxygen from water. So, large separation system with large water pumps, having large surface areas, and large battery sources are needed. Exhalation gases are used to solve this problem. Theses gases contain some oxygen, nitrogen, and carbon dioxide; they contain less oxygen and more carbon dioxide compared to air. Therefore, reduction of the amount of carbon dioxide is necessary. If exhalation gases are employed appropriately, the separation device can be made more compact. Inlet water mixed with exhalation gases is supplied into the separation device, and dissolved gases are separated from the mixed water as it passes through the device. The inlet part of a typical separation system with a water delivery pump before the membrane module has more than one atmosphere. Hence, a compressor is used to mix the exhalation gases. In this study, the pressure at the inlet due to the use of a suction pump after the membrane module was less than one atmosphere; hence, compressors were not required. Separation characteristics were studied using a separation device without a compressor. The use of exhalation gases led to an increase in the amount of dissolved gases being separated. As the amount of inlet exhalation gases was increased, the separation of dissolved gases was increased as well.

• Food Science and Preservation
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• v.16 no.1
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• pp.128-133
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• 2009

We performed an experiment of keeping the extension of raw and semi-dried flounder (Pleuronectes herzensteini). The effect of with (WG) or without gill (OG), drying degree (20% drying: 20D, 40% drying: 40D) and storage temperature($5^{\circ}C$) and 0.1% chitosan-ascorbate (CA) treatment of vacuum packaging flounder on the growth of contaminated microorganism during storage for 10 days were investigated. Total aerobacter (TA) in the OG-treated raw flounder was $0.29{\sim}0.44$ log cycle lower than that of WG-treated flounder. Also, the number of Staphylococcus aureus (SA) and E. coli (EO) in OG were lower compared with WG. The number of TA, SA and EO in 20 D among 0 D, 20 D and 40 D stored at $5^{\circ}C$ were lowest. Especially, the SA and EO was $0.13{\sim}0.53$, 0.3-0.88, and 0.13-0.74 log cycle lower compared with raw flounder. The growth of TA, SA and EO separated from raw flounder in tryptic soy broth were completely inhibited by 0.1% CA. The anti-biotical effect of CA of two microorganisms SA and EO that separated from flounder, and the growth of all of them were 90% (SA), 96% (EO) inhibited at the 0.1% CA. The inhibition times at $37^{\circ}C$ in soy broth was 36 hr. However when CA was added directly to flounder, it appeared inhibition effect to 0.88 log cycle. The effect of CA was better when gills removed and 20% drying.

• Journal of Aquaculture
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• v.7 no.3
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• pp.165-175
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• 1994

Attempts were made to find out nitrogen and phosphorus loads to aquatic environment resulting from feeding Nile tilapia (Oreochromis niloticus). Two different size groups, small and large, were used. The average sizes of small and large tilapia were 65.2 g and 389.2 g respectively, and three kinds of commercial diets were used for each size. The 3 kinds of commercial diets for tilapia contained in average 33.8% crude protein ($5.4\%$ nitrogen) and $1.4\%$ total phosphorus. The load of nitrogen and phosphorus were measured by subtracting the amounts of nutrients retained in the body of fish from consumed nutrients. Sixty, five percentage of total feces was excreted within 24 hours after feeding at $23^{\circ}C$. Nitrogen content in the feces was higher in large fish than small ones. The apparent digestibility of dietary protein for small and large tilapia was $90.0\%$ and $89.7\%$, respectively. Availability of dietary phosphorus for small and large tilapia was $44.7\%\;and\;51.4\%$, respectively. The total load of nitrogen and phosphorus per 1 metric ton of tilapia production was 49.5kg and 6.3kg, respectively, for small ones with feed conversion ratio (FCR) of 1.4, and 61.3 kg and 13.4kg, respectively, for large ones with the FCR of 1.8. Nitorgen balance appeared that small and large tilapia excreted $7.1\%\;and\;9.9\%$ of consumed nitrogen through fecal-nitrogen and $55.5\%\;and\;62.3\%$ through urine and gills, retaining $37.4\%\;and\;27.8\%$ in the body, respectively. These results show that small fish pollute less than large fish, excreting less and retaining more nutrients in the body.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.172-182
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• 2009

This study was to analyze characteristics based on tolerance and trophic guilds and to determine the level of total mercury in tissues of sentinel species, Zacco platypus at 3 sampling sites of the Mangyeong River in 2007. Total sampled fishes were 26 species and the most dominant species was Zacco temminckii (47%). Fish community analysis was resulted that eveness index and diversity index showed low value at S1. However, diversity index and richness index at other sites showed high. According to various guilds analysis, relative abundance of sensitive species was 70% and 42% at S1 and S2, respectively. While sensitive species were decreased (1%) and tolerant species were increased (60%) at S3. It was mainly carried to the impacts of wastewater treatment plants near the location. Relative abundance of insectivore species was decreased from up (S1) to midstream area (S3). In addition, chemical water quality, based on analyses of BOD, COD, TP, TN, EC, MPN and SS concentration showed similar trends. Qualitative Habitat Evaluation Index (QHEI) was averaged 164, judged as "good" habitat condition. Average concentrations of total [Hg] was 146.9 ${\mu}g$ $kg^{-1}$. In the muscles of total [Hg] was the highest, and then followed by kidney, vertebrae, liver, and gills. According to FDA standards (500 ${\mu}g$ $kg^{-1}$) of Korea, total [Hg] has not affected to the individual fish health.

• Journal of fish pathology
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• v.13 no.2
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• pp.121-127
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• 2000

From August to October 1998, over 60% mortality of cultured striped beakperch Oplegnathus fasciatus was occurred in net cages along the southern coast of Korea. Moribund fish showed some clinical signs of lethargic behavior, dark coloration or decoloration, severe gill anemia and enlargement of spleen. Also enlarged basophilic cells showing Feulgen -positive reaction were observed in the tissue section of spleen, kidney, liver and heart of the diseased fish. GF cells inoculated with spleen homogenate of diseased fish produced cytopathic effect of enlarged and rounded cells, therefore the causative virus was isolated from diseased fish. Striped beakperch fingerlings intraperitoneally inoculated with the causative virus ($10^4TCID_{50}$/0.1 ml) revealed symptoms similar to those of naturally infected fish and died from 7 to 14 days post injection. Transmission electron microscopy revealed that the causative virus was enveloped icosahedral particle with 120~130 nm in diameter. PCR products of the expected size (500 bp) were amplified with a primer set based on the ATPase gene of RSIV(red sea bream iridovirus) using template DNAs which were extracted from the spleen of diseased fish and GF cells inoculated with the causative virus. According to the analysis of nucleotide sequence of these PCR products, the sequence from ATPase cDNA gene of the causative virus showed 95% homology with that of RSIV. These results indicate that the mass mortality in the cultured striped beakperch was caused by the infection of iridovirus similar to RSIV.

• Journal of fish pathology
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• v.25 no.3
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• pp.271-277
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• 2012

The practical monitoring was performed to survey the mortalities in aquaculture farms of olive flounder, rockfish, rainbow trout, Japanese eel, white shrimp and abalone in South Korea from May to November, 2011. The aquatic organism disease inspectors, who have the national licenses for the diagnosis and prevention of aquatic disease and have close relationship with the farms, investigated the rates and causes of mortalities according to the standard manual. In 70 flounder farms, the cumulative mortalities rate was 27.9%, and the mortalities were caused by scuticociliatosis, streptococcosis, VHS, non-infectious loss, vibriosis and gliding bacterial disease. The moralities rate of 30 rockfish farms was 13.6%, and those were mainly contributed by gill flukes and streptococcosis. Most of mortalities of rainbow trout were caused by non-infectious loss and protozoan white spot disease. The mortalities rate of Japanese eel was 0.6% by edwardsiellosis, protozoan white spot disease and gill flukes. The loss rate of white shrimp was 71.2%, and most of them was related with non-infectious ones, such as carnivalization, transportation loss, and the rest was caused by viral white spot disease. The mortalities rate in the abalone farms was 10.7% and all of them were related with non-infectious loss.

• Journal of fish pathology
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• v.23 no.3
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• pp.281-291
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• 2010

Crytocaryon irritans infection of rock bream was investigated in embankment fish farm from July to December 2009. Prevalence variation was 20.0~88.0% that was high in september and was low in July. While no mortality was found in July and August, it occurred after mid september. Environmental conditions during the survey period were water temperature $19.3{\sim}24.3^{\circ}C$, dissolved oxygen $5.0{\sim}7.1\;mg\;L^{-1}$ and salinity 31.9~33.7 psu, and the water temperature during mortality season was $24.0^{\circ}C$. External symptom of the rock bream was secretion mucus but swimming showed fine in the early infected period. While, the symptoms in the severe outbreak season were excess of mucus, falling off tail and congestion, bleeding spot the surface and weakened swimming. We observed free living and parasitic stages in the gills and body surface of rock bream. Hepato somatic index (HSI) was $1.9{\pm}1.1{\sim}3.5{\pm}1.7%$, which was low in the September being mortality season but was high in November. The percentages of hematocrit infected with Crytocaryon irritans were 37.3% and 41.0% in July and August, respectively while they gradually decreased to 32.1% and 24.2% in september and October, respectively. Total cholesterol and Triglyceride values rapidly decreased by October. After mortality, AST and ALT were 7 and 5 folds higher compared to non-mortality season.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.593-600
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• 1999

The survival rates of Littorina brevicula exposed to experimental concentration regimes of TBTCl, HB and Cd on the large and the small size individuals during 80 days were $80\%$ at 0,9ppb TBTCl, 40 and $25\%$, respectively at 200ppb Hg, and 75 and $45\%$, respectively at 100ppb Cd. The growth rates of the experimental animals exposed to each concentration for 80 days was 0.023mm/day at control, 0.019mm/day at 0.1ppb and 0.014mm/day at 0.9ppb TBTCl, 0.022 mm/day at 5ppb, 0.008 mm/day at 200ppb Hg, and 0.017 mm/day at 5ppb, 0.008mm/day at 100ppb Cd. The respiration rates and excretion rates of the experimental animals exposed to chronic concentration of TBTCl, Hg and Cd were decreased until approximatively 40 days and increased after, Toxic effect of pollutants on L. brevicula was highest at TBTCl. The histological injury of L. brevicula exposed to TBTCl, Hg and Cd was shown at gill, digestive organ and muscle, respectively.

• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.678-690
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• 2020

In this study, the histological changes of Zacco platypus exposed to discharge from a Wastewater Treatment Plant (WTP), which is a point source, for a long time (2 to 3 years) were compared to the same species at a reference site (Ref.). Overall, tissues displayed various lesions in samples obtained at the point where discharge water from the point source was mixed. In the skin tissue, mucus cells from the epithelial layer expanded to the multilayered epithelium, indicating the immune system was activated. Epithelial cell detachment and proliferation were most prominent in the gills, which may have adversely affected circulation and respiration. Our data suggest immune system collapse was due to stimulation by aquatic substances. Both the fish phase analysis and the water quality analysis demonstrated depreciated conditions at the point source as compared to the reference stream, supporting the histological health evaluation results. These data together suggest a histological approach can also be used to assess water quality, and to an even higher degree when combined with other existing methods. Given the presented evaluation, improvement in the water quality of water discharged from WTP's is required.

• Analytical Science and Technology
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• v.19 no.4
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• pp.342-351
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• 2006

This study was carried out to estimate the contents of heavy metals in big marine 17 kinds of fishes (n=89) which had been sold at wholesale market in Seoul from January to December in 2005. The contents of mercury (Hg), lead (Pb), cadmium (Cd), chrome (Cr), copper (Cu) and arsenic (As) were measured by the mercury analyzer and atomic spectrophotometer (AAS) in the flesh, liver, and gill part. The values of heavy metals in fishes were as follows ($Mean{\pm}SD$, mg/kg). The average contents of heavy metals in the fishes were Hg $0.08{\pm}0.01mg/kg$, Pb $0.17{\pm}0.32mg/kg$, Cd $0.34{\pm}0.07mg/kg$, Cr $0.05{\pm}0.05mg/kg$, Cu $1.14{\pm}0.13mg/kg$, As $0.24{\pm}0.22mg/kg$. Of the heavy metals detected in 3 parts, liver was measured highly in the all heavy metals. Of the heavy metals detected in countries, Hg, Pb, and Cu were measured highly in New Zealand, Cd and As in Norway, Cr in Korea. The range of heavy metal contents in imported and domestic fishes are low level, except of mercury contents of imported Yellow porgy (n=2), compared with regulation value of anther nations and Korea. And the contents of heavy metal in the imported fishes are natural. By correlation coefficients between fish livers of all subjects, a significant correlation was found Hg (r=0.989, p<0.01), Pb (r=0.978, p<0.01), Cd (r=0.991, p<0.01), Cu (r=0.998, p<0.01), As (r=0.198, p<0.05) in fish livers and flesh.