• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.474-482
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• 2019

Disease monitoring in wild aquatic animals is necessary to obtain information about disease occurrence, disease agents, and the transmission of diseases between wild and cultured species. In this study, we monitored viral diseases in wild marine fish and crustacea caught by trawl in Korea in April and October 2018. We monitored the viral diseases in 977 fish from 39 different species and 287 crustacea from 14 different species. In fish, we collected kidney and spleen to detect viral hemorrhagic septicemia virus (VHSV), red sea bream iridovirus (RSIV), marine birnavirus (MABV), hirame rhabdovirus (HRV), and lymphocystis disease virus (LCDV). In crustacea, we monitored white spot syndrome virus (WSSV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), taura syndrome virus (TSV), infectious myonecrosis virus (IMNV), yellowhead disease virus (YHDV), and white tail disease virus (WTDV) using pleopods, pereiopods, gills, muscle, and hepatopancreases. Although none of the viral diseases tested in this study were detected in the samples, these results will help disease control between aquaculture species and wild aquatic animals.

• Journal of Bio-Environment Control
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• v.15 no.2
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• pp.177-183
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• 2006

The summer production of sweet pepper in Korea which cultured in the highland area such as Hapchon is essential for a year-round export, but has the problem, fruits lose easily those marketability. This study was carried out to find changes of fruit quality in response to storage on sweet pepper cultivars in summer. Seven cultivars of sweet peppers, 'Jubilee', 'Plenty', 'Goal', 'Romeca', 'Derby', 'Midas' and 'Maximalia' were obtained iron growers in Hapchon which was highland of 600-800m from sea level and stored at $10^{\circ}C$ with box packing. Fruit quality was evaluated every 4days up to 4weeks. The weight loss of 'Jubilee' was the lowest, that of 'Romeca' was the highest. The firmness of 'Goal' was maintained highly for 4weeks and the red cultivars was higher than those of other color cultivars. The lightness of 'Jubilee' was sensitively affected by storage duration. Seeds of 'Plenty' and 'Derby' were plentifully browned after 4weeks storage. The occurrence of fruit rotting was after 16-204ay storage and those of 'Plenty' and 'Maximalia' were the earliest. The marketability of 'Jubilee' and 'Romeca' maintained by 70% for 16 days was the highest, but most cultivars lost those by 20% after 24days storage. It may be suggested that the marketability of sweet pepper producted in summer can be stored at $10^{\circ}C$ for 2weeks to maintain that of 80%.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.4
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• pp.291-300
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• 2007

The crayfish-shaped artificial bait for octopus drift line is manufactured, into which is made to insert ordinary bait. The effects of the artificial bait are confirmed through the analysis of octopus' behavior in the laboratory in comparison with the existing bait of pig-fat skin, and the investigation of the octopus catch on the sea, and in addition, the examination of the water quality in relation to the bait to be inserted into the artificial bait is done together. The artificial bait is red in color, 10.5cm in the length of the body, and 29g in weight. The octopus behavior in relation to the bait in the laboratory has shown a good result in which more than 30% of the octopuses rushed to the artificial bait. In the analysis of the octopus sitting time by the bait, the octopus stayed longer with the artificial bait(63.7%) than the pig-fat skin(25.1%). The octopus sitting time at the artificial bait inserted with frozen squid(48.8％, 44.6％) is shown to be longer than that of the pig-fat skin(36.9％) or boiled fish paste(21.2％). In the analysis of sitting frequency to the bait, the case of the artificial bait(total 17 times) was more than that of the pig-fat skin(total 3 times), and the case of the artificial bait with frozen squid attracted the octopuses more frequently than that of the pig-fat skin or the boiled fish paste. In the field experiment, the fishing boat A(Manseon-ho, 1.22tons) caught the total 93 octopuses, while the fishing boat B(Ilho-ho, 0.73tons) caught the total 154 octopuses, all of which weighed less than 9.0kg. In the comparison with the total catch, the case with the artificial bait was a little higher than that of the pig-fat skin($^{**}p\;<\;0.05$). In the analysis of the water quality in relation to the baits, the COD showed the descending order of frozen squid(0.57mg/g), boiled fish paste(0.18mg/g), and pig-fat skin(0.10mg/g), and the case with frozen squid was the highest and the case of the pig-fat skin, lowest. The total phosphorus, like the COD, showed the highest in frozen squid(0.02mg/g), and in case of the total nitrogen, unlike the COD, the pig-fat skin was shown to be the highest(0.006mg/g).

• Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.232-241
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• 1998

Fatty acid compositions of 35 species of marine invertebrates (13 species of Bivalvia, 10 species of Gastropoda, 4 species of Cephalopoda, 4 species of Crustacea, 2 species of Ascidacea, 2 species of Holothuroidea) were studied using gas-liquid chromatography. Total lipids in all samples were very low, ranging from $0.24\%$ to $1.96\%$. The prominent fatty acids were 16:0, 20:5 (n-3), 22:6 (n-3), 18:0, 16:1 (n-7), 20:4 (n-6), 18:1 (n-9) and 18:1 (n-7) in the majority of marine invertebrates. Polyunsaturated fatty acid (PUFA) was the richest fatty acid group in all invertebrates, accounting for $55.3\pm6.70\%$ of total fatty acids (TFA), followed by saturated $(26.2\pm4.33\%)$ and monounsaturated fatty acid $(18.5\pm5.87\% )$. No correlation was found between total lipid content and each fatty acid group. Cephalopoda contained the highest level of n-3 PUFA $(54.6\pm5.17\%)$, while Holothuroidea and Gastropoda contained the lowest level of n-3 PUFA, accounting for $26.5\pm4.44\%$ and $28.4\pm4.04\%$, respectively. Bivalvia and Ascidacea are plankton feeders, which were rich in 20:5 (n-3) and 22:6 (n-3). Carnivorous species of Cephalopoda were prominently rich in 22:6 (n-3), ranging from $26.7\%$ to $46.1\%$ of the TFA. However, some species of Gastropoda are seaweed feeder (herbivorous), which contained high level of 20:4 (n-6) compared to plankton feeder and carnivorous species. In addition, blue and red colored sea cucumbers, and turban shells with and without apophyses belong to the same species, but they live in different habitats. These organisms were found to have different fatty acid compositions. Therefore, fatty acid compositions of these invertebrates might be affected by their different environments, particularly their diet.

• Korean Journal of Environment and Ecology
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• v.28 no.6
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• pp.613-626
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• 2014

Seaweeds were identified after qualitative sampling at 14 stations of Dokdo coasts from May to July 2013 and seaweeds and animals inhabiting 23 Eisenia bicyclis plants were examined to evaluate its ecological role. Biomass was calculated by using regression between stipe length and weight of E. bicyclis. A total of 128 species were identified, including 18 green, 35 brown, and 75 red algae. Coarsely branched form was dominant functional group occupying 47.66% and 91 species (71.09%) were in ESG I group, growing in stable environmental coast. Also, R/P, C/P, and (R+C)/P were 2.14, 0.51, and 2.66, respectively showing temperate and mixed flora. Biomass and density of E.bicyclis were $23.74kg\;m^{-2}$ and 64 fronds $m^{-2}$. Twelve seaweeds and 83 animal species (15 Annelida, 25 Mollusca, 34 Arthropoda, 3 Echinodermata, and 6 others) were observed from 23 holdfasts and Ericthonius pugnax was dominant taxon having 538 (43.11%) of 1,248 animal individuals. These results indicate that E.bicyclis is a keystone species showing very important ecological role. In conclusion, the number of seaweeds increased because of intensive research and dominance of coarsely branched form and ESG I group seaweeds, representing that environmental condition of Dokdo is still intact.

• Korean Journal of Ichthyology
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• v.25 no.4
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• pp.189-199
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• 2013

The distribution status and habitat characteristics of the endangered species, Lethenteron reissneri were investigated in 2011~2012 in Korea. During the study period, L. reissneri were collected 60 stations among 755 sampling stations investigated. The total numbers of ammocoetes and adults were 208 and 435, respectively from eight stations of the Han River drainage system, four stations of Geum River drainage system, 32 stations of Seomjin and Yeongsan River drainage systems, and 16 stations of Nakdong River drainage system. The Han and Geum river drainage systems, the Sapkyo Stream and independent streams running toward the East Sea were estimated to have suffered sudden reductions of population density, whereas the Seomjin River drainage system showed increased population density compared with historic occurrence records. L. reissneri inhabited the middle-upper stream of clean water with well-developed rapids and lots of aquatic organisms. According to IUCN Red List categories and criteria L. reissneri was assessed to be vulnerable (VU) [B2ab (ii,iii,iv,v);D1] because of the rapid reduction of the occupying areas and the small number of mature individuals. Besides the distribution status and habitat characteristics we discussed the conservation strategies of L. reissneri.

• Korean Journal of Ichthyology
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• v.29 no.2
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• pp.139-145
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• 2017

The spontaneous color mutant, albino individuals of genus Misgurnus, are rarely discovered in Korea and there are difficult to identify morphological species due to lack melanin pigmentation. In this study, we developed a genetic identification method for the species of albino Misgurnus individuals based on phylogenetic analysis by using recombination activating gene 1 (rag1) and cytochrome b (cytb) region of mitochondrial DNA. As a result of molecular phylogenetic analysis, three clades were identified as Misgurnus mizolepis, M. anguillicaudatus and M. mohoity. The homology of the cytb sequences of M. mohoity was best match to that of M. mohoity sequences in GenBank database. As a result of species identification of 25 albino Misgurnus individuals based on the phylogenetic tree, the red-eye type was identified as 16 M. anguillicaudatus and one M. mizolepis. The remaining three individuals were identified as one M. mizolepis ♀${\times}$M. anguillicaudatus ♂, and two M. mohoity ♀${\times}$M. anguillicaudatus ♂, respectively. In addition, the five black-eye type individuals were identified as one M. anguillicaudatus, three M. mizolepis and one M. mohoity. Therefore, this genetic identification method will be an useful techniques for species or hybrid identification in genus Misgurnus.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.1
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• pp.20-31
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• 2018

Marine parasitoid Amoebophrya infects and kills various bloom-forming dinoflagellates and strongly influences the harmful algal bloom dynamics. We investigated the effect of temperature on survival, infectivity, generation time of the parasite from the parasitoid Amoebophrya sp. and the harmful dinoflagellate host Akashiwo sanguinea system. Temperature had a significant effect on the parasite generation time and infectivity. While the lower temperature ($15^{\circ}C$) arrested parasite intracellular development and infectivity, resulting in the longer generation time ($115{\pm}0.1h$), the higher temperatures ($25^{\circ}C$ and $20^{\circ}C$) accelerated the parasite development, with the generation times of $58{\pm}0.1h$ and $83{\pm}0.1h$, respectively. Parasite prevalence (percent of host infected) was $71.5{\pm}0.30%$, $54.3{\pm}1.68%$, and $29.6{\pm}1.42%$ at $25^{\circ}C$, $20^{\circ}C$, and $15^{\circ}C$, respectively. These results suggest that biological control by parasitism on A. sanguinea bloom would not be highly effective during low water temperature season. Further, water temperature would be an important factor of bottom-up controls for the host-parasite population dynamics.

• 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.23 no.2
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• pp.155-163
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• 2010

The epidemiological study was performed to survey the prevalence of fish pathogens in cultured olive flounder, Paralichthys olivaceus from 2005 to 2007. In this study, the fish pathogens were detected from 1,528 among 2,238 fish samples collected yearly in 5 sites from February, May, August and November. Annual incidences for three years show a yearly increase and there were 60.6% in 2005, 66.7% in 2006 and 72.3% in 2007, respectively. Seasonal prevalence was 63.5% in February, 67.4% in May, 75.1% in August and 64.4% in November for three years. The detection rates of 6 viral pathogens were 35.6% in 2005, 44.6% in 2006 and 24.4% in 2007 and the peak rate was 55.4% at adult size group (above 41cm). Viral nervous necrosis virus (24.7%) has been the most predominant virus in this investigation, while much lower rates were noted in viral haemorrhagic septicemia virus (10.6%) and red sea bream iridovirus (0.9%).