• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.743-752
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• 2015

We studied the spatio-temporal microalgal (phytoplankton and benthic diatoms) and environmental changes of the Hajeonri intertidal zone from February to November 2014. Seawater and phytoplankton analysis were conducted all through the months. The species, composition and abundance of phytoplankton and environmental factors were measured. As a result, diatom was dominant among a total of 113 species identified. On a seasonal basis (Feb. May, Aug., Nov.), we carried out studies on benthic diatoms on the surface of the sediments and their habitats at nine stations on the transect line at Hajeonri at low tide. The grain of the surface sediments was mainly composed of sandy silt and sandy mud. Organic pollution level was low. Benthic microalgal biomass (chlorophyll ${\alpha}$) was high in the spring and summer. A total of 163 benthic diatom species were identified. Navicula sp.1 and Paralia sulcata were dominant over the study period. Five diatom species were observed both in water column and on surface sediment at the same time.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.97-97
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• 2003

유용 수산생물인 전복, 소라, 성게 등 무척추동물의 종묘생산에 있어 부착 규조류는 수서 생태계의 일차 생산자로서 유생의 변태와 변태 후의 초기 먹이생물로 활용되고 있으며 최근에는 단일 부착규조류의 실내 배양을 통해 유용 수산생물 종묘의 대량 생산을 유도하고 있다. 부착규조류의 생물량 및 종 조성에 따라 이들 조식동물의 성장과 먹이 효율성에 커다란 영향을 끼친다. 이 연구는 종묘생산의 환경 조건과 동일한 현장에서 유수식 수조에 투명 플라스틱 부착파판(30$\times$40cm)을 설치하여 1997년 10월부터 1999년 4월까지 실내수조에 설치한 부착파판을 10일 간격으로 회수하여 부착된 규조류의 생물량과 환경적 특성을 조사하였다. 실험기간 동안 자연광을 55~75% 차단한 상태에서 실험을 진행하였고 수온과 염분은 각각 14.1$^{\circ}C$~28.6$^{\circ}C$와 32.5$\textperthousand$~35.3$\textperthousand$의 범위를 보였다. 실험기간 동안 부착규조류의 총 출현종수는 27종(17속 25종 2미동정종)으로 중심규조류(centric diatom)가 4종 그리고 우상규조류(pennate diatom)가 23종이었다. 현존량의 30% 이상을 점유하는 부착 규조류들은 Bacillaria paxillifera, Cocconeis scutellum, Diatoma hyalina, Navicula mollis, Nitzschia sp., Synedra tabulta 등 6종이 우점하였다. 부착규조류의 현존량은 2.5$\times$$10^3$~ 5.0$\times$$10^{5}$ cells $cm^{-2}$ 의 분포 범위로 1999년 4월에 가장 높고 1997년 10월에 가장 낮았다. Chlorophyll $\alpha$량 ($\mu\textrm{g}$ chl $\alpha$ $cm^{-2}$)은 0.02 ~ 1.72 $\mu\textrm{g}$ chi $\alpha$ $cm^{-2}$의 범위로써 부착규조류의 현존량과 유사한 분포 특성을 보였다. 유수식 실내수조에 부착된 부착규조류의 부착 형태, 우점종과 현존량은 배양 시기에 따라 종간 특이성을 보였다.다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.1
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• pp.55-64
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• 2005

Spatio-temporal variations of phytoplankton abundance and nutrient concentrations were investigated in the Namdaechon estuary, Yangyang, from April to December, 2003. A total of 51 phytoplankton species were identified with 32 diatom species in the study area. Phytoplankton abundance ranged from 14 cells/mL to 3,798 cells/mL. Small sized benthic and pennate-type diatoms like Cymbella spp., Fragilaria spp., Navicula spp., Synedra spp. were dominant at throughout the whole study area. Various planktonic species like Chlamydomonas sp., Peridinium spp., Euglena spp., Cryptomonas spp. etc. were abundant especially at the estuary of the Namdaechon, from May to August. Phytoplankton bloom (>3,000 \;cells/mL) occurred from the late May to mid June. After September when the sandbank of estuary was broken by the typhoon 'Maemi', planktonic species disappeared. These planktonic species were followed by oceanic diatoms, Skeletonema costatum and Chaetoceros spp.. Concentrations of dissolved inorganic nitrogen (DIN) and silicate were relatively high at the upstream in summer. In May, before phytoplankton bloom, high concentrations of phosphate $(>3.5\;{\mu}mol/L)$ were observed at all the study area. These results suggested that spatio-temporal variation of phytoplankton in the Namdaechon estuary was related to formation of sandbank at the mouth of the estuary, fluid speed affected by sandbank and nutrients supplied in spring. High correlation $(r^2=0.928)$ between chlorophyll a and biological oxygen demand (BOD) implies that BOD was related to phytoplankton abundance in the Namdaechon estuary.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.363-367
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• 1983

Low salt fermented products of anchovy, Engraulis japonica, caught in the coasts of East Sea of Korea, were prepared tentatively and also discussed the retarding effect of rancidity of the product by the addition of BHA or red pepper. Fresh anchovies were purchased from Kichang fish market. The raw samples were mixed with $8\%$ table salt, $0.5\%$ lactic acid, $6\%$ sorbitol, $4\%$ ethyl alcohol and $0.02\%$ BHA or $0.5\%$ red pepper and filled in the glass bottles and sealed with the cap. Conventional fermented product of anchovy as a control was prepared from fresh anchovy and $20\%$ salt only. After preparation, the products were fermented for 90 days at room temperature. Amino-nitrogen, TBA value, peroxide value and viable counts of bacteria of these products were determined and also evaluation of their qualify was compared with control product by sensory evaluation during fermentation. Amino-nitrogen contents of the low salt products reached a peak in 55 days of fermentation, and the volatile basic nitrogen contents ranged $100\;mg\%$ even after 90 days of fermentation. Thiobarbituric acid value of the product with $0.02\%$ BHA showed a little increase up to 65 days of fermentation regardless of salt contents, while that of the control product increased sharply up to 65 days and then decreased gradually. BHA was effective on retarding rancidity of fermented products of anchovy and red pepper was also slightly effective. All the products showed the highest cell population in about 55 days of fermentation. Judging from the results of analysis and sensory evaluation, the low salt fermented product of anchovy could be prepared with $8\%$ salt, $0.5\%$ lactic acid, $6\%$ sorbitol, $4\%$ ethyl alcohol and $0.02\%$ BHA or $0.5\%$ red pepper to the fresh round anchovy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.2
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• pp.176-185
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• 2013

Seasonal species composition and biomass of microphytobenthos were examined at the intertidal flats of Jinsanri, Taean, Korea, from April to December 2011. In total, 121 species were identified, including 109 diatoms, 5 blue-green algae, and 5 dinoflagellates. Seasonal variation in species number ranged from 49 to 56 species (minimum in October and maximal in April), while vertical variation across three different shore levels ranged from 64 to 77 species with maximum at high and minimum at low shore. Species diversity ranged from 3.22 to 3.42 seasonally and from 3.50 to 3.17 across vertical shore levels. Seasonal average values of the normalized difference vegetation index and the vegetation index were 0.06 and 1.14, respectively. Chlorophyll a concentrations were $66.00-120.73mg/m^2$, with a seasonal minimum and maximum in July and October, respectively, and a vertical shore maximum of $137.35mg/m^2$ at mid shore. Phaeopigment concentrations peaked in October ($50.78mg/m^2$) and at high shore ($61.58mg/m^2$) and were lowest in December ($22.53mg/m^2$) and at low shore ($15.28mg/m^2$). The number of microphytobenthos ranged from 78,556 to 287,898 cells/$cm^2$, reaching a maximum in April and a minimum in July. The diatoms Paralia sulcata, Navicula sp., and Delphines surirella were dominant at all tidal levels over the study period. Dinoflagellates were dominant in July at low shore, and blue-green algae were abundant between July and October at mid shore. In conclusion, species composition and primary production of microphytobenthos exhibited clear seasonal and vertical patterns.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.3
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• pp.177-186
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• 1970

The spawning of the abalone, Haliotis discus hannai, was induced In October 1969 by air ex-position for about 30 minutes. At temperatures of from 14.0 to $18.8^{\circ}C$, the youngest trochophore stage was reached within 22 hours after the egg was laid. The trochophore was transformed into the veliger stage within 34 hours after fertilization. For $7\~9$ days after oviposition the veliger floated in sea water and then settled to the bottom. The peristomal shell was secreted along the outer lip of the aperture of the larval shell, and the first respiratory pore appears at about 110 days after fertilization. The shell attained a length of 0.40 mm in 15 days, 1.39 mm in 49 days, 2.14 mm in 110 days, 5.20 mm in 170 days and 10.00 mm in 228 days respectively. Monthly growth rate of the shell length is expressed by the following equation :$L=0.9981\;e^{0.18659M}$ where L is shell length and M is time in month. The density of floating larvae in the culture tank was about 10 larvae per 100 co. The number of larvae attached to a polyethylene collector ($30\times20\;cm$) ranged from 10 to 600. Mortality of the settled larvae on the polyethylene collector was about $87.0\%$ during 170 days following settlement. The culture of Nauicula sp. was made with rough polyethylene collectors hung at three different depths, namely 5 cm, 45 cm and 85 cm. At each depth the highest cell concentration appeared after $15\~17$ days, and the numbers of cells are shown as follows: $$5\;cm\;34.3\times10^4\;Cells/cm^2$$ $$45\;cm\;27.2\times10^4\;Cells/cm^2$$ $$85\;cm\;26.3\times10^4\;Cells/cm^2$$ At temperatures of from 13.0 to $14.3^{\circ}C$, the distance travelled by the larvae (3.0 mm In shell length) averaged 11.36 mm for a Period of 30 days. Their locomation was relatively active between 6 p.m. and 9 p.m., and $52.2\%$ of them moved during this period. When the larvae (2.0 mm in shell length) were kept in water at $0\;to\;\~1.8^{\circ}C$, they moved 1.15cm between 4 p.m. and 8 p.m. and 0.10 cm between midnight and 8 a.m. The relationships between shell length and body weight of the abalone sampled from three different localities are shown as follows: Dolsan-do $W=0.2479\;L^{2.5721}$ Huksan-do $W=0.1001\;L^{3.1021}$ Pohang $W=0.9632\;L^{2.0611}$