• 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.

• 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.

• Development and Reproduction
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• v.24 no.1
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• pp.19-30
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• 2020

The pH of water is one of the main environmental factors exerting selective pressure on marine and freshwater organisms. Here, we focus on the influence of pH on an organism's ability to maintain homeostasis and investigate the effects of acidification on immunity-related genes and osmotic pressure during early development of the olive flounder, Paralichthys olivaceus. The aim of our study was to determine the influence of various pH levels on the fertilized eggs and larvae of P. olivaceus. Gametes of P. olivaceus were artificially introduced and the resulting fertilized eggs were incubated at pH 4.0 (low), 6.0, and 8.0 (equivalent to natural sea water; control). We found that all eggs sank from the water column at pH 4.0. After 38 h, these eggs showed slow development. Hatching occurred more slowly at pH 4.0 and 6.0 and did not occur at all at pH 4.0. Result of gene expression, caspase and galectin-1 were expressed from the blastula to pre-hatch stages, with the exception of the two-cell stage. HSP 70 was also steadily expressed at all pH levels over the five days. The osmolality of fertilized eggs differed marginally at each stage and across pH levels. So, this results demonstrates that low pH level is detrimental to P. olivaceus fertilized eggs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.2
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• pp.144-153
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• 2014

Both docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) have attracted increasing attention since the first epidemiological report on the importance of n-3 essential fatty acids. Lipids in microbial cells play various biological roles and, consequently, much research has been carried out on their role in cell physiology. The lipid composition of microorganisms can exhibit considerable variations depending on environment. The effects of culture conditions, temperature (15, 20, 24, 28, 32 and $36^{\circ}C$), salinity (10, 20, 30, 40 and 50 psu), pH (pH5, 6, 7, 8 and 9), rotation speeds (50, 100, 150 and 200 rpm), carbon sources, nitrogen sources and C/N ratio on the production of docosahexaenoic acid, fatty-acid profiles, and acids secreted to the broth culture by the oleaginous microorganism, Schizochytrium mangrovei (KCTC 11117BP), were studied. Temperature (initially $28^{\circ}C$), salinity (20 psu), pH (pH7), rotation speeds (100 rpm), organism fatty acids, and secreted acids in the broth were varied during cultivation of S. mangrovei. At pH 7.0, S. mangrovei was able to accumulate lipids up to 40% of its biomass, with 13% (w/w) DHA content. The monosaccharides glucose and fructose, and yeast extract were suitable carbon and nitrogen sources, respectively. The primary omega-3 polyunsaturated fatty acid produced was docosahexaenoic acid.

• Korean Journal of Environmental Biology
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• v.28 no.3
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• pp.125-132
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• 2010

In order to assess the effect of pollution on marine ecosystem, we examined the plankton health assessment at 16 stations during summer season in Jinhae Bay. The organic and inorganic pollutant sources (dissolved organic carbon; DOC, chemical oxygen demand; COD and Chlorophyll a; Chl.a), including planktonic orangism such as enterobacteria Escherichia coli, heterotrophic bacteria (HB), autotrophic nano-flagellates (ANF), heterotrophic nano flagellates (HNF), ciliate and harmful algal bloom species (HABs) were used to characterize marine ecosystem health assessment. Of these, we tentatively selected those items Chl.a, HABs, HB and E. coli for plankton health index (PHI). Also, the scoring criteria for each metric were based on a statistical analysis and then, the grades are rated on four levels. As a result, the ecological assessment of these data reveals that PHI in Jinhae Bay is rated as "Good or fair" for overall conditions. The present study suggests that the PHI might be considered as one of important management tool to assess marine ecosystem health of Jinhae Bay.

• Journal of Aquaculture
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• v.19 no.3
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• pp.178-182
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• 2006

We studied new observation method about take process of rotifer by marine fish larvae. Till now, we can not accurate observation and count of first rotifer feeding day and/or feeding numbers of rotifer by marine fish larvae. Because take rotifer is ingested and disappeared in the digestive system of fish larvae. However we suggest possible observation method for these problems. The trophi is mastication organ of rotifer, and has only one in each rotifer individual. The trophi is left in the mastication organ because sole indigestible organ of rotifer. Therefore we can accurate observation and count of first rotifer feeding day and/or feeding rotifer numbers of marine fish larvae by trophi observation method (RTCM; Rotifer Trophi Counting Method).

• ALGAE
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• v.34 no.3
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• pp.217-228
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• 2019

The marine brown algal genus Colpomenia has a worldwide distribution, with five species reported in Korea and Japan. However, no studies to date attempted to identify the number of species and geographical distribution of Colpomenia along Chinese coast. To fill the biodiversity knowledge gap, we analyzed 63 mitochondrial cox3 and 62 mitochondrial atp6 sequences of Colpomenia specimens collected from 30 localities along the Chinese coast. Maximum likelihood and Bayesian inference trees suggest the presence of at least three Colpomenia species (i.e., C. peregrina, C. claytoniae, and C. sinuosa) in China. C. peregrina and C. claytoniae are documented for the first time. C. sinuosa was only found in the South China Sea and its distribution didn't overlap with that of C. peregrina which was found in the Yellow-Bohai Sea and the East China Sea. C. claytoniae appears to be confined to three isolated islands in the East and the South China Sea, where it occurs in sympatry with, respectively, C. peregrina and C. sinuosa. Future study can focus on comparing eco-physiological differences of Colpomenia species in response to environmental variables and exploring possible genetic hybridization / introgression at inter-specific contact zones.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.3
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• pp.277-289
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• 2024

Climate change has led to a significant increase in jellyfish populations globally, causing various problems. For power plants that use nearby seawater for cooling, the intrusion of jellyfish into intake systems can block the flow, leading to reduced output or even shutdowns. This issue is compounded by other small marine organisms like shrimp and salps, making it urgent to develop solutions to prevent their intrusion. This study addressed the problem using the BioSonics DT-X 120 kHz scientific fish finder to conduct preliminary tank experiments. We also deployed underwater acoustic and camera buoys around the intake of nuclear power plant, utilizing a bidirectional communication system between sea and land to collect data. Data collection took place from July 31, 2023 to August 1, 2023. While harmful organisms such as jellyfish and salps were not detected, we successfully gathered acoustic data on small fish measuring backscattering strength (SV). Analysis showed that fish schools were more prominent in the evening than during the day. The highest fish distribution was observed at 3:30 AM on July 31 with an SV of -44.8 dB while the lowest was at 12:30 PM on the same day with an SV of -63.4 dB. Additionally, a solar-powered system was used to enable real-time data acquisition from sea buoys with smooth communication between the land server and the offshore buoy located 1.8 km away. This research developed an acoustic-based monitoring system for detecting harmful organisms around the intake and provided foundational data for preventing marine organism intrusion and planning effective measures.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.1
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• pp.71-78
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• 2009

Korea Marine Environment Management Corporation (KOEM) has waste oil facilities in 13 ports to collect and treat waste oil, bilge, etc. from ships based upon the Marine Environment Management Act of Korea and MARPOL 73/78 convention. Those facilities were designed and have been operated simply to discharge water under the level 15 ppm of oil contents. However, bad smells occurred from rotten organic matters in waste water and direct discharge of harmful substances to receiving water caused civil appeals. Therefore, KOEM tried to develop new process for treatment of oily waste water from ships, which could mitigate harmful substances, save cost, calm down civil appeals and contribute to marine environment preservation. This process consists of 3 steps to remove oil contents via gravity variation at first, $O_3$ input to contact water and organism deposition by inputting condensate deposits. Then finally upper water will be discharged, and the deposited substances in the bottom will be compressed through spinning machine to transfer to the designated contractors for treatment of wastes. This is very effective and innovative in that it could reduce 3 or 4 steps compared with existing process and mitigate not only waste oil concentration but also hard resolving materials such as colloid, ABS, phosphorus, nitrogen and bad smells. This method is expected to minimize bad smells and harmful gases, to save more than 10% of maintenance cost, and to arrange the good base for garbage treatment business dealing with waste water and bad smell.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.1
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• pp.66-69
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• 2000

The common harpacticoida copepod species Tigriopus japnnicus was often obseued in the mass culture of marine rotifer tanks of sea farming stations. In this study, we investigated the co-existing effect of T. iaponicus to the rotifer Brachionus rotundiformis population growth. The culture conditions as temperature, salinity, culture volume, photo period, culture period and observation interval were 25{\circ}C, 22ppt, 40ml, 12L:12D, 16 deys$ and every two days during the experimental period, respectively. Nannochloropsis oculata was used as the food for the two testing organisms. After counting the growth of rotifer and copepod, they were transferred to new culture tank with N. oculata at the density of $7{times}10^5\;cells/ml$. The population growth of B. rotundiformis was suppressed by T. japonicus when these two organisms were mix-cultured comparing to single culture of B. rotundiformis. But population growth of T, japomcus was not affected by the presence of B. rotundiformis. The interspecific relationships of prey-predation and food competition were not observed in the combination culture of rotifer B. rotundiformis and copepod T japonicus.