• Journal of Aquaculture
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• v.21 no.3
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• pp.167-171
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• 2008

Common co-existing organism Euplotes (Ciliate, Protozoa) well often observed in the rotifer mass culture tank of marine fish larval rearing stations. Ciliate protozoa (Euplotes) competed to condensed food (micoralgae, Nannochloropsis oculata) with rotifer (Brachionus rotundiformis). As results, rotifer density was rapidly decrease, and what is more, the rotifer was wiped out by dominant bacteria species at that time.

• Proceedings of KOSOMES biannual meeting
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• 2006.05a
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• pp.79-83
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• 2006

Displayed result that handle particle contaminant and hydrospace organism included in number of ballast that is happened in ship using automatic bade washing filter. Reason that remove first contaminant that is included in number of ballast is that heighten processing effect of after processing process. of the filter. Another advantage is to drop off the solids with controlling revolution of drum screen in pretreatment filtration process. The fact that it is easy to attach and detach a several type of screen for getting the expected water quality is another advantage. Filter rotation speed at 1.0rpm is filter resistance 3.0bar and 3.0rpm is filter resistance 2.8bar. Filter out impurities from ballast water over 6.0rpm is filter resistance 26bar and 10rpm is filter resistance 2.5bar. Filtration system removal aquatic organism over $80{\mu}m$ in ballast water. This study shows that the filtration treatment system has a potential for the treatment of ballast water.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.1
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• pp.71-76
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• 2002

To understand the effect of heated effluent from a nuclear power plant on marine organism, experimental culture of Halocynthia roretzi was carried out at heated effluent of Wolsung nuclear power plant from January to December 1996. Temperature was $11.2\~27.9^{\circ}C$ and salinity was $32.54\~34.59\%_{\circ}$ during the culture period, The Growth of H. roretzi on lower area of Bonggil-ri (St. 1) was not normal in height, breadth and weight due to heated effluent. Daily growth rate (DGR) of H. roretzi about Kampo area (St, 4) was significant other station, and St. 1 was significant from other station except St. 4, Mytilus edulis was major fouling organism (over $90\%$) that were M. edulis, Dideninum moseleyi, Styela clava in experiment culture farm. St. 1 was higher (mean 143 individual) and St. 4 was lower (mean 56 individual) appearance attached of M. edulis. Growth of H. roretzi reduced when attached number of M. eduiis was increased, because correlation between DGR and number of M. edulis was negative.

• Journal of Aquaculture
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• v.13 no.1
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• pp.63-67
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• 2000

Tigriopus japonicus harpacticoida copepod was a common copepoda species as food organism for the marine fish larval rearing. However T. japonicus was difficult to stable culture except for a mixed culture with rotifer. Available food source for the successfully stable culture of T. japonicus was investigated in this study. T. japonicus did not utilization Nannochloropsis oculata instead of that. T japonicus utilized to products from rotifer culture tank. The products from rotifer culture tank was composed of rotifer feces and co-existing aquatic bacteria. The nauplius I stafe and copepodid I stage of T. japonicus showed grown whenproducts from rotifer culture tanks was fed. Specially we observed higher density of nauplii than that of copepodites and ovisac carrying females in the experimental culture populations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.605-610
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• 2001

We investigated the effects of salinity on an estuarine cladoceran, Diaphanosoma celebensis as a substitute live food organism of Artemia, which has been used for the next step of rotifer, in the course of seedling production of marine fishes, Culture density for growth, possibility of stable culture (RPGI: Relative Population Growth Index) and food feeding activity (RCN: Remaining Cell Numbers) of D. celebensis were investigated at intervals of 5 ppt under 10 steps of different saline conditions from 0 to 45 ppt. According to the results, the experimental group, which was regarded as the best condition of culture density for growth, stable culture possibility (RPGI) and good food feeding activity (RCN), was salinity culture condition of 20 put, and relative stable culture conditions were observed under saline concentrations $15\~35\;ppt$. Their functions under culture conditions of lower or higher salinities than 20 ppt appeared remarkably to be decreased, while all individuals were dead under the saline condition of 0 ppt after the beginning of the experiment. From these results of this study, it is assumed that estuarine cladoceran, D. celebensis can be cultured easily as a substitute live food organism of Artemia in the course of seedling production of marine fishes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.388-396
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• 2021

Antimicrobial resistance patterns of Escherichia coli were investigated. Strains were isolated from 310 shellfish, 36 crustaceans, and 12 fish collected off the West Coast of Korea from April 2019 to October 2020. Two hundred and ninety-five E. coli strains were isolated from shellfish, 100 from crustaceans, and 54 from fish. Strains isolated from shellfish showed the highest resistance to ampicillin (27.5%), whereas those from crustaceans were resistant to sulfisoxazole (30.0%) and those from fish were resistant to ampicillin (59.3%) and sulfisoxazole (59.3%). Ceftazidime resistance was observed in strains isolated from short neck and hard clams, whereas gentamicin resistance was observed in strains from fish. Multi-drug resistance was observed in 56 strains (48.7%) isolated from shellfish, 11 (28.2%) from crustaceans and 27 (73.0%) from fish. Depending on the source of isolation, the strains showed specific antimicrobial resistance tendency. Strains isolated from shellfish showed 12 different multi-drug resistance patterns, whereas those from crustaceans showed high resistance (59%) to a single antimicrobial agent and those from fish showed a broad trend of multi-drug resistance to more than eight antimicrobials.

• Journal of fish pathology
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• v.34 no.1
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• pp.63-70
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• 2021

As a part of research to elucidate the pathogenesis of so called Soft Tunic Syndrome(STS), that caused mass mortalities in the cultured sea squirts, Halocynthia roretzi, the epidemiological and pathological analysis were done to both clinically normal and diseased groups of the farms of Tongyoung and Geoje coastal areas in southeast sea from February to July, 2008. In the histological finding of the tunic, most of individuals showed tunic softness syndromes that included the disarrangement and destruction of tunic fiber with the simultaneous presence of flagellates-like cells, recently suspected as main agents of tunic softness syndromes. Simultaneously, the intensive degenerative changes of the skeletal muscle of diseased sea squirts were recognized. The changes were characterized with the hyalinization and condensation of muscle fibril and hemocytic infiltration in the muscle fibers. Those were thought to be a kind of typical Zenker's necrosis as in the skeletal muscle of higher vertebrates. Besides of the diseased sea squirts, Zenker's necrosis of skeletal muscles were seen in the normal ones. Epidemiological inquiry for diseased groups revealed that the higher incidences of tunic softness syndrome were recorded in the fast growing groups and in the sites presuming the organic pollution. And Higher malondialadehyde(MDA) and glutathione peroxidase(GPx) activity were detected in the groups showing STS. Those results suggested that Zenker's necrosis of body muscles was a kind of"nutritional myopathy" by oxidative stress. Conclusively, it was considered that Zenker's necrosis of body muscles gives an important clue for elucidating pathogenesis of STS of cultured squirts. And it seems that the necrosis were caused by the oxidative stress to body muscle during abnormal rapid growth of sea squirts.

• Fisheries and Aquatic Sciences
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• v.27 no.2
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• pp.87-99
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• 2024

Global climate change, followed by an increase in anthropogenic activities in aquatic ecosystems, and species invasions, has resulted in a decline in aquatic organism biodiversity. The Batanghari River, Sumatra's longest river, is polluted by mercury-containing illegal gold mining waste (PETI), industrial pollution, and domestic waste. Several studies have provided evidence suggesting a decline in fish biodiversity within the Batanghari River. However, a comprehensive evaluation of the present status of biodiversity in this river is currently lacking. The species under investigation were identified through various molecular-based identification methods, as well as morphological identification, which involved the use of neighbor-joining (NJ) trees. All collected specimens were initially identified using morphological techniques and subsequently confirmed with molecular barcoding analysis. Morphological and DNA barcoding identification categorized all specimens (1,692) into 36 species, 30 genera and 16 families, representing five orders. A total of 36 DNA barcodes were generated from 30 genera using a 650-bp-long fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene. Based on the Kimura two-parameter model (K2P), The minimum and maximum genetic divergences based on K2P distance were 0.003 and 0.331, respectively, and the average genetic divergence within genera, families, and orders was 0.05, 0.12, 0.16 respectively. In addition, the average interspecific distance was approximately 2.17 times higher than the mean intraspecific distance. Our results showed that the COI barcode enabled accurate fish species identification in the Batanghari River. Furthermore, the present work will establish a comprehensive DNA barcode library for freshwater fishes along Batanghari River and be significantly useful in future efforts to monitor, conserve, and manage fisheries in Indonesia.

• The Korean Journal of Pesticide Science
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• v.16 no.1
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• pp.69-77
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• 2012

To evaluate the effect of endocrine disruption chemicals (EDCs) to aquatic organisms, muddy loach (Misgurnus anguillicaudatus) was exposed to low concentration methomyl for 21 days in order to identify the effect of biomarkers and endocrine. Vitellogenin (VTG) in blood plasma, which used widely as validated biomarker for endocrine disruption, was significantly greater in male fish exposed to 0.4 mg/L and 2 mg/L methomyl, and in female fish exposed to 0.08 mg/L, 0.4 mg/L, and 2 mg/L methomyl for 21 days (p<0.05). This results suggest that methomyl have probability of endocrine disruption to organism on aquatic system. While inhibition of Acetylcholinesterase (AChE) activity and increase of DNA damage in comet assay were verified by fish exposed to methomyl, change of ethoxyresorufin-O-deethylase (EROD) activity was not occurred, comparing the control group (p<0.05). Indicators at the level of organism such as condition factor (CF), hepato-somatic index (HSI), and gonado-somatic index (GSI) were not influenced by exposure of methomyl. In conclusion, these results showed the possibility of methomyl in regard to not only endocrine disruption but also impacts on biochemical biomarkers to aquatic organisms.

• Fisheries and Aquatic Sciences
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• v.9 no.2
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• pp.57-63
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• 2006

A bacterial strain capable of hydrolyzing carrageenan was isolated from the coast of Busan in Korea. The isolated strain (HS5322) is aerobic, gram-negative, rod-shaped, and motile. Comparison of the 16S rDNA of the isolate with that of known Pseudomonas sp. showed that sequence similarity was at most 95%, implying that the isolate is a new Pseudomonas species. The organism grew optimally at NaCl concentrations of 2.0 to 2.5%. The optimum temperature and pH for carrageenase production in a 72-h flask culture containing 1% carrageenan was $20^{\circ}C$ and pH 8.5, respectively. Of the synthetic substrates tested, the highest enzyme activity was obtained with p-nitrophenyl ${\beta}$-D-galactopyranoside.