• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.4
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• pp.342-347
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• 2002

Ciliates have the possibility of a new live food in marine finfish culture because of their wide range of body size, thin tell wall, show motility, and fast reproduction rate. In this research, six species of ciliates were isolated from south coast and salt pond in Korea. The fitness of these species as a live food was evaluated in terms of size, motility, suspensibility and cell density. As the result, Euplotes sp. (K-1) was found suitable to be a new live food which might substitute rotifers, Brachionus plintilis and B. rotundiformis in fish larvae culture. The modified $F{\emptyset}yn's$ Erdschreiberd media, MErds-2 with the addition of glycine, glucose and yeast extract increased six times higher growth rate of Euplotes sp. (K-1) than the basic F$\emptyset$yn's Erdschreiberd media. The optimum water temperature, pH and light intensity for this ciliates were $22.5^{\circ}C$, 8 and 2,000 lux, respectively, and its culture environmental range was relatively wide, On the other hand, this ciliate fed baker's yeast, Saccharomyces cererisiae grew up to 1,240 inds./mL with the inocula of 100 inds./mL within 7 days. The results of the study showed that Euplotes sp. (K-1) has a potential to be utilized as a new live food in fish larvae culture.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.1
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• pp.57-62
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• 1985

The three tide pools of Kanagawagen Aburatsubo coast, Japan were studied for 5 months (June-October, 1991) to know the physicochemical factors and changes of the microflora, In the tide pools salinity was ${\simeq}35\%0$, temperature range was $14{\sim}32^{\circ}C$ and pH range was $7.4{\sim}8.9$. Particulate organic carbon (POC) was $255{\sim}3980\;{\mu}g-at/l$, and total phosphate-P was $1.0{\sim}27.0\;{\mu}g-at/l$. The numbers of suspended bacteria and heterotrophic bacteria on the algae were $10^4{\sim}10^7/ml$ and $10^6{\sim}10^8/g$, respectively. Bacterial flora isolated from the Samples were Acinetobacter spp., Moraxella spp., Flavobacterium spp. and Pseudomonas spp., While Acinetobacter spp. was predominant among them. T. japonicus occurred dominantly with densities of $2200{\sim}7000/l$ during $August{\sim}september$. During this period the sharp increases of the unicellular microalgae and the protozoans were observed. According to the experimental results (POC, total phosphate-P, numbers and composition of bacterial flora), T. japonicus seemed to inhabit the environment with high eutrophication and high variability.

• The Korean Journal of Malacology
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• v.31 no.2
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• pp.123-127
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• 2015

${\beta}$-Glucan is a polysaccharide that is widely used as an adductive in fish feed to facilitate immune stimulation. This study aimed to investigate the effect of ${\beta}$-glucan on immune responses in the Manila clam Ruditapes philippinarum. For this purpose, three groups of R. philippinarum were exposed to 0%, 0.1%, or 1% ${\beta}$-glucan in sea water for 1 hr/day for 2 weeks using an immersion method. Thereafter, two immune parameters-phagocytic rate and antibacterial activity-were measured. R. philippinarum exposed to 1% ${\beta}$-glucan showed an approximate 30% significant increase in phagocytic rate. In addition, ${\beta}$-glucan significantly limited the growth of the pathogenic bacteria Vibrio tapetis, V. parahaemolyticus, and V. ordalii. Moreover, the mortality rates of ${\beta}$-glucan-treated clams decreased during a 17-day experiment. Our study suggests that treatment with ${\beta}$-glucan significantly increases the immune responses in R. philippinarum, and that immersion is a simple and effective method for immune stimulation in this species.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.478-485
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• 2013

Fish field survey, especially fish distribution and their ecological characteristics, was performed in the downstream region of Gyeongan stream during the period of before (June) and after (October) the summer monsoon in 2010. Depending on the characteristics of each site, fyke net or casting net was used for fish sampling. Feeding classification was determined by the analysis of stomach contents. Total number of family and species sampled were 5 and 17, respectively. The dominant family was Cyprinidae (12 species), and relative abundance (RA) of the most dominant species, Lepomis macrochirus and Zacco platypus, was 38% and 24%, respectively. Exotic species and Korean endemic species observed were 3 (423 individuals, RA 44%) and 4 (98 individuals, RA 10%), respectively. Tolerance guild analysis as characteristics of ecological indicators revealed an undoubtedly high percentage (97%), compared to others as reflected by the identification of just one sensitive species. Analysis of trophic guilds showed that L. macrochirus dominated among insectivores (44% RA). The food of L. macrochirus composed of, aquatic insects, benthic invertebrates, zooplankton, Chironomidae, and waterweed. Thus, we determined that L. macrochirus could be classified as insectivores (partially carnivores) in this study. Conversely, Z. platypus consumed Cladocera exclusively, greater than 90% of their feed. We presume that stable isotope analysis would identify the exact position of these species in the food web.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.1
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• pp.37-46
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• 2000

We investigated the temporal and spatial variations in heterotrophic dinoflagellates (hereafter HTD) and ciliates from June to September 1997 in the waters off Kohung, Korea where red tides dominated by harmful dinoflagellates had occurred from August to October since 1995. We took water samples five times from 5-7 depths at 3 stations in this study period. A total of 17 HTD species were present and of these species in the genus Protoperidinium were 11. The species number of tintinnids (hereafter TIN) present totalled 15 and several naked ciliate (hereafter NC) species were observed. The species numbers of HTD and TIN rapidly increased between August 1st and 21st and then reached to the maximum numbers of 13 and 10, respectively, on August 27 when red tides dominated by Gyrodinium impudicum were first observed in the study area. However the species numbers drastically decreased on September 22. The maximum densities of HTD, TIN, and NC were 45, 39, 57 cells $ml^{-1}$, respectively. ADAS, calculated by averaging the densities of a certain species in the all samples collected from all depths and stations at a sampling period, most increased between August 1st and 21st and then reached to the maximum density of f cells $ml^{-1}$ on August 27 for HTD, while did between August 21st and 27th and up to 7 cells $ml^{-1}$ for TIN. Unlike ADAS of HTD and TIN, that of NC did not change much with the maximum of 8 cells $ml^{-1}$ on August 27th. The pattern of the temperal variation in the species number and ADAS of HTD was similar to that of diatoms and the distributions of Protoperidinium spp. and diatoms had a strong positive correlation. This evidence suggests that HTD, in particular Protoperidinium spp. be a grazer on diatom. In general, the densities of HTD, TIN, and NC decreased with going to stations located in the outer bay. Therefore, the availability of suitable prey and distance from the coastal line might be responsible for the distribution of HTD, TIN, and NC. The results of the present study provide a basis for further experiments for the feeding by dominant HTD, TIN, and NC on dominant phytoplankton including red tide species and for understanding food webs in the planktonic community before, during, and after the red tide outbreak.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.144-154
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• 2008

The purpose of this study was to describe quantitatively trophic structures and to analyze energy flows in the Lake Namyang using the Ecopath with ecosim (Walter et al., 1997). The sampling and analyses were carried out at 6 sampling sites of the Lake Namyang during May and November in 2007. A total of 10 groups were considered in this study (detritus, macrophytes, phytoplankton, zooplankton, zoobenthos, Cyprinus carpio, Carassius cuvieri, Carassius auratus, Pseudobagrus fulvidraco and other fishes) to assess the trophic relationship, energy flows and interactions between them. As a result, it was concluded that Lake Namyang was consisted of primary producers (Detritus, Macrophytes, Phytoplankton), primary consumers (Zooplankton, Zoobenthos, Cyprinus carpio, Carassius cuvieri, Carassius auratus, Other fishes) and secondary consumer (Pseudobagrus fulvidraco). The total system throughput was estimated at $14.1\;kg\;m^{-1}\;year^{-1}$ including a consumption of 39%, exports of 21%, respiratory flows of 12% and flows into detritus of 28%. MTI analyses indicate that Pseudobagrus fulvidraco have positive impact on Cyprinus carpio, Carassius cuvieri and Carassius auratus. On the other hand, other fishes have negative impact on Cyprinus carpio, Carassius cuvieri and Carassius auratus. All the functional groups except detritus had a negative impact on themselves and this may show within-group competition for the same resources.

• Korean Journal of Environmental Agriculture
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• v.22 no.1
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• pp.16-25
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• 2003

Manun Reservoir, located in Andong district has the capacity of 2 million tons in irrigation water supply with the drainage area of $23.8\;km^2$. Manun Reservoir is over fifty year old, and shallow in depth. The ratio of drainage area (DA) to reservoir surface area (SA) as an effective physical parameter on water quality was 56.1 and was higher than those of other agricultural reservoirs. The ratio of reservoir storage (ST) to SA in Manun Reservoir was 4.79, and the mean depth was below 8m. Both ratios of DS/SA, total area (TA)/ST and ST/SA in Manun Reservoir were relatively higher than those in other agricultural reservoir and natural lakes in Korea. These physical parameters in Manun Reservoir, however, had a eutropic potential significance. Average of COD, IN, and TP in Manun Reservoir were 11.1 mg/L 1.426 mg/L, 0.093 mg/L, respectively. In the inflow stream of Manun Reservoir, the TN ($1.426{\sim}3.809\;mg/L$) was higher than those in reservoir. Only Lyngbya spp. was dominant in phytoplankton for this study period and Gymnodinium spp., Peridinium spp., and Cryptomonas spp. were dominant in zooplankton. According to the Carlson's trophic status index, Mnnun Reservoir was eutrophic in 1996, 1997, and 1999, and hypertrophic in 1998.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.22-22
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• 2003

로티퍼는 해산어와 담수어뿐만 아니라 식용어와 관상어에 이르기까지 모든 어류의 인공 종묘 생산 과정에서 초기 먹이생물로 이용되고 있는 중요한 동물 플랑크톤이다. 그리고 로티퍼를 초기 자어의 첫 먹이로 사용하는 것을 시작으로 알테미아, 코페포다 또는 초미립자 사료 등을 사용하는 어류 인공종묘 생산 과정에서의 먹이계열이 확립되어 있다. 그러나, 사육하고자 하는 어종에 따라 초기 자어기에서 로티퍼를 섭이하는 시기와 사육 일령별 자어의 로티퍼 포식수를 알 수 있는 정확한 방법이 없다는 이유로 지금까지는 자어의 로티퍼 최초 포식 일령 및 로티퍼 포식수를 개개의 연구자들 나름대로의 방법으로 관찰하여 왔다. 일반적으로 자어가 로티퍼를 포식하였는지의 여부 및 포식수는 자어 소화기내에 존재하는 소화가 진행되기 전의 로티퍼 몸체의 수를 계수하는 방법으로 이루어졌다. 로티퍼의 체내에는 섬모환으로 모은 수중의 먹이 현탁액을 소화기계로 이동시키기 전에 먹이를 잘게 다지고 부수는 기능을 하는 저작기 (trophi)가 존재한다. 그리고 이 저작기는 로티퍼의 종에 따라서 다른 형태를 하고 있는 것으로 알려져 있다. 이 연구에서는 자어가 섭이한 로티퍼는 어류의 소화기내에서 소화가 진행되는 과정에서 로티퍼의 체 구조 중 저작기가 쉽게 소화되기 어렵고 소화기관의 연동 운동에 의해서도 쉽게 그 모양이 손상되지 않는다는 것을 발견하고 이 저작기의 수를 계수하므로서 로티퍼의 최초 섭이 일령 및 일령별 로티퍼 포식수를 계수할 수 있는 방법을 검토하였다. 그 결과, 소화기내의 잔존 로티퍼 몸체만으로 계수 관찰하던 기존 방법에 비교하여 로티퍼의 저작기를 계수하는 방법을 이용할 경우 보다 신뢰도가 높은 결과를 도출할 수 있음을 확인하였다. 경제적 가치의 우수성 때문만은 아니다. 미국은 자국의 대두 생산자들이 생산해 낸 대두를 판매하면서 조성한 자조금을 모아 대두의 생산성을 향상시키기 위한 연구 개발과 국내외 시장을 확대하기 위한 마케팅 활동에 쓰고 있다. 이런 자조 노력은 비단 미국의 대두 농민들에게만 국한된 것이 아니다. 가깝게는 일본의 수산업과 해산어 양식산업의 발전은 중앙 및 지방 정부, 수협과 같은 어민 조합 및 연근해 수산업 종사자들이 출연한 기금을 통해 이루어지고 있음을 지난 8월 북해도의 양식산업을 시찰했을 때 확인할 수 있었던 사실이다. 이제 우리나라도 국민소득 1만불 시대를 넘어 2만불 시대를 열기 위한 청사진을 그릴 만큼 모든 경제의 규모가 확대되었을 뿐 아니라 질적으로 고도화되었다. 우리에게 필요한 것은 성숙된 산업사회에 걸맞는 각 산업 주체들의 의식이다. 한국의 양식산업도 자조 정신을 갖추어 생산성 향상에 초점을 맞춘 양식기술의 개발, 환경 보전을 고려한 양식장 관리 및 소비를 확대하기 위한 유통시스템의 선진화에 스스로 투자를 해야 할 시기에 와 있다.치가 완전히 익은 15일 후에는 무첨가 김치, 0.1%, 0.2% 및 0.3% 고분자 키토산 김치의 젖산균 수는 5.4X107 cfu/g, 3.3X107 cfu/g, 8.6X106 cfu/g 및 2.6X106 cfu/g로 나타났다. 5. 발효가 진행 중에 대장균 군 수가 시간과 더불어 대장균군 수가 모든 구에 있어서 6일까지는 서서히 증가하다가 그 후부터는 대장균 군 수가 감소하였다. 즉, 발효초기에는 모든 구가 2.0X104∼4.0X105 cfu/g이었고, 6일 경에는 8.9X104∼4.5X105 cfu/g로 약간 증가하였으며 15일후에는 키토산 무첨가 김치가 2.0X

• Korean Journal of Ecology and Environment
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• v.44 no.3
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• pp.280-291
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• 2011

Bottom-up approaches to control of Microcystis aeruginosa blooms were comparatively investigated through an in situ mesocosm experiment using aquatic plants (Iris pseudoacorus). In the mesocosm experiments, floating I. pseudoacorus, seemed to be effective in controlling massive M. aeruginosa blooms in an agricultural reservoir, exhibiting a close coupling with temporal variations in Chl-a and DO concentration. Shading by floating I. pseudoacorus resulted in a reduced phytoplankton abundance inhibiting light energy availability. Moreover, I. pseudoacorus may suppress phytoplankton growth through the excretion of chemical substances, likes a allelopathy, that inhibit phytoplankton photosynthetic activity. The $^{15}N$ atom % of I. pseudoacorus showed higher values than POM, suggesting that I. pseudoacorus assimilates DIN predominantly compared to phytoplankton, which was mostly M. aeruginosa. This result strongly suggests that the M. aeruginosa bloom should be regulated by aquatic plants, like I. pseudoacorus, this approach can affect zooplankton composition. This is the first study that has used stable isotope tracers to evaluate the biomanipulation efficiency through floating I. pseudoacorus.

• Journal of fish pathology
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• v.17 no.3
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• pp.159-169
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• 2004

Bacterial wihte enteritis ocurred by infection of V. ichthyoenteri is a devastating disease in olive flounder (Paralichthys olivaceus) hatcheries in Korea. Since white enteritis has been a problem in aquqtic industries, necessity of a rapid detection method is increased. In an attempt to develop rapid PCR method the detection of V. ichthyoenteri, we examined the 16S-23S rRNA intergenic spacer region(ISR) of V. ichthyoenteri and developed species-specific primer for V. ichthyoenteri. The intergenic spacers were amplified by primers complementary to conserved region of 16S and 23S rRNA genes. The intergenic spacer region between the 16S and 23S rRNA genes of V. ichthoenteri were investigated by PCR fragment length typing and DNA sequencing. Analysis of the ISR sequences showed that V. ichthyoenteri contains one types of polymorphic ISRs. The size of ISRs ranged 348bp length and not contains tRNA genes. Mutiple alignment of representative sequences from different Vibrio species revealed several domains of high sequence variability, and allowed to design species-specific primer for detection of Vibrio ichthyoenteri. PCR. The specific of the primer was examined using genomic DNA prepared from 19 different Vibrio species, isolated 18group Vibrio species. The results showed that the PCR reaction using species-specific primer designed in this study can be used to detect V. ichthyoenteri.