• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.691-696
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• 2001

The first bloom of Cochlodinium polykrikoides was observed in the estuary of Nak-dong river near Pusan in Korea in 1982. Since then, there have been irregular blooms, sometimes spread over the adjoining .to Jinhae Bay even though it was confined to the bay and its vicinites until 1988. It had been outbroken frequently in the adjacent to Tongyeong, Geoje, Namhae and Yeosu coast since 1989. It became widespread along the coast of the South Sea to the East Sea of Korea in 1995. And in October in 1998 and 1999, the bloom had been taken place in Kunsan coast of Yellow Sea. According to the observations in situ, the frequency of occurrence has been increased year by year. The prevailing bloom season was from July to October with peak in September. The duration of the bloom became longer with the year, and sometimes lasted more than one month. The density of the bloom did not exceed 5,000 cells $mL^{-1}$until 1991, but it increased year by year to the highest of 43,000 cells $mL^{-1}$ in 1999. With respect to the assembleges of species in dinoflagellate blooms, C. polykrikoides was one of the important species with diatoms and the other dinoflagellates in 1980s. But since then, C. polykrikoides made an almost monospecific bloom. Based on two decadal observations of C. polykrikoides blooms, it became widespread throughout whole coast of the Korea, persistent for about one or two month long in some year, and monospecisc high density blooms. It was reported that significant fish mortalities were caused by this harmful dinoflagellate blooms especially in the fishfarms accomodating intensive fish cages such as Tongyeong, Namhae-do, Geoje, Yeosu and Geomun-do fishfarming yards. This widespread and persistent harmful algal blooms impede the development of marine aquaculture industries.

• Korean Journal of Ichthyology
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• v.32 no.3
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• pp.117-129
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• 2020

The body color pattern in fish is a distinctive feature for species identification. The blass bloched rockfish Sebastes pachycephalus is a commercially important marine fish species, distributed in the central and southern parts of Korea and south Hokkaido of Japan. It has a morphological feature divided into four subspecies according to with or lacking distinct spots on the body surface, and to the location of markings on the body surface. However, the genetic basis of body color pattern of S. pachycephalus is still unknown. Thus we analyzed the transcriptome of S. pachycephalus skin samples using RNA-seq analysis to investigate functional genes related to body color patterns. The experimental skin samples were prepared by classified into 'Wild type' (lacking distinct spots and markings) and 'Color type' (with distinct spots and marking). Two skin sample transcriptomes were compared pairwise and the results revealed that were 164 differentially expressed unigenes in the skin samples of 'Wild type' and 'Color type'. Gene Ontology analysis of 164 differentially expressed unigenes showed that these genes were included in the functional group of molecular function (2 genes), biological process (46 genes), and cellular component (6 genes). There were several genes that body color type skin specific expression and the genes were CTL (Galactose-specific lectin nattectin), CUL1 (Cullin-1), CMAS (N-acylneuraminate cytidylyltransferase), NMRK2 (Nicotinamide riboside kinase 2), ALOXE3 (Hydroperoxide isomerase ALOXE3), SLC4A7 (sodium bicarbonate cotransporter 3). Our study is the first attempt to search for functional genes involved in the formation of body color patterns in S. pachycephalus. The differentially expressed unigenes obtained in this study can be used as candidate genes for functional gene study related to body coloration of fish.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.69 no.1
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• pp.49-60
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• 2024

A region can be divided into cultivation zones based on homogeneity in weather variables that have the greatest influence on crop growth and yield. This study classified the cultivation zone of soybean using weather indices as a prior study to classify the agroclimatic zone of soybean. Meteorological factors affecting soybeans were determined through correlation analysis over a 10 year period (from 2013 to 2022) using data from the Miryang and Suwon regions collected from the soybean yield trial database of the Rural Development Administration, Korea and the meteorological database of the Korea Meteorological Administration. The correlation between growth characteristics and the minimum temperature, daily temperature range, and precipitation were high during the vegetative growth stages. Moreover, the correlation between yield components and the maximum temperature, daily temperature range, and precipitation were high during the reproductive growth stages. As a result of k-means clustering, soybean cultivation zones were divided into three zones. Zone 1 was the central inland region and southern Gyeonggi-do; Zone 2 was the southern part of the west coast, the southern part of the east coast, and the South Sea; and Zone 3 included parts of eastern Gyeonggi-do, Gangwon-do, and areas with high altitudes. Zone 1, which has a wide latitude range, was further subdivided into three cultivation zones. The results of this study may provide useful information for estimating agrometeorological characteristics and predicting the success of soybean cultivation in South Korea.

• ALGAE
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• v.34 no.2
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• pp.111-126
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• 2019

The phototrophic dinoflagellate Biecheleriopsis adriatica is a small suessioid species characterized by a fragile thin wall. Although the morphology of this dinoflagellate is well established, there is currently little information available on its distribution and the environmental factors that influence this distribution. Thus, to investigate the spatial and seasonal distributions of the vegetative cells of B. adriatica in Korean waters, surface water samples were collected on a seasonal basis from 28 stations in the East, West, and South Sea of Korea and Jeju Island from April 2015 to October 2018, and abundances of the vegetative cells of B. adriatica were quantified using quantitative real-time polymerase chain reactions, for which we developed the species-specific primer and probe set. Simultaneously, major environmental parameters, including temperature, salinity, nutrient concentrations, and dissolved oxygen concentrations were measured. The vegetative cells of B. adriatica were detected at 20 of the 28 sampling stations: 19 stations in summer and 6 in autumn, although from no stations in either spring or winter. The ranges of water temperature and salinity at sites where this species was detected were $17.7-26.4^{\circ}C$ and 9.9-34.3, respectively, whereas those of nitrate and phosphate concentrations were not detectable-96.2 and $0.18-2.66{\mu}M$, respectively. Thus, the sites at which this species is found are characterized by a narrow range of temperature, but wide ranges of salinity and concentrations of nitrate and phosphate. The highest abundance of the vegetative cells of B. adriatica was $41.7cells\;mL^{-1}$, which was recorded in Jinhae Bay in July 2018. In Jinhae Bay, the abundance of vegetative cells was significantly positively correlated with the concentration of nitrate, but was negatively correlated with salinity. On the basis of these findings, it appears that the abundance of B. adriatica vegetative cells shows strong seasonality, and in Jinhae Bay, could be affected by the concentrations of nitrate.

• Economic and Environmental Geology
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• v.50 no.2
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• pp.129-143
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• 2017

The shallow sediments in the southwestern Ulleung Basin consist of mass flow deposits such as slide/slump and debris flow deposits (DFD), caused by slope failure. These sediments are proven to be important in studying geological disaster and stability of the seafloor. In this paper, we analysised the flow accumulation and slope failure susceptibility of the Ulleung Basin on the basis of multi-beam data, collected in this area. We also studied the distribution pattern and the seismic characteristics of the DFD in the uppermost layer of the Ulleung Basin on the basis of seismic data. The slope susceptibility was calculated as the frequency ratio of each factors including slope, aspect, curvature and stream power index (SPI), which causes the slope failure. These results indicate that the slope failure is frequently to occur in the southern and western continental slope of the Ulleung Basin. The sediment flow (mass flow) caused by the slope failure converges to the north and northwest of the Ulleung Basin. According to the seismic characteristics, the uppermost layer in study area can be divided into four sedimentary unit. These sedimentary units develop from the south and southwest to the north and northwest in association with slope susceptibility and flow accumulation.

• Economic and Environmental Geology
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• v.41 no.6
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• pp.747-761
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• 2008

In order to experiment the acoustic remote classification of seabed sediment, we achieved ground-truth data(i.e. video and grab samples, etc.) and developed post-processing for automatic classification procedure on the basis of 300 kHz MultiBeam Echo Sounder(MBES) backscattering data, which was acquired using KONGBERG Simrad EM3000 at Sock-Cho Port, East Sea of South Korea. Sonar signal and its classification performance were identified with geo-referenced video imagery with the aid of GIS (Geographic Information System). The depth range of research site was from 5 m to 22.7 m, and the backscattering amplitude showed from -36dB to -15dB. The mean grain sizes of sediment from equi-distanced sampling site(50 m interval) varied from 2.86$(\phi)$ to 0.88(\phi). To acquire the main feature for the seabed classification from backscattering amplitude of MBES, we evaluated the correlation factors between the backscattering amplitude and properties of sediment samples. The performance of seabed remote classification proposed was evaluated with comparing the correlation of human expert segmentation to automatic algorithm results. The cross-model perception error ratio on automatic classification algorithm shows 8.95% at rocky bottoms, and 2.06% at the area representing low mean grain size.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.1125-1133
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• 2021

This study attempted to understand seawater characteristics like chlorophyll concentration (CHL), total suspended matter concentration (TSM), absorption characteristics, and remote sensing reflectance around Weno Island, Micronesia, located in the South Pacific Ocean near the equator. 50 in-situ measurement from May to June 2013 were analyzed and compared with data from around Korean peninsula. CHL around Weno Island was 0.11-0.49 mg/m³ (average 0.26 mg/m³), and TSM was 0.03-0.31 g/m³, (average 0.16 g/m³), showing typical clear water characteristics. Absorption coefficient of total suspended matters at 443 nm showed over 0.5 times less than that from East Sea and the slope of absorption coefficient spectrum of dissolved organic matter showed much larger than that of Korean peninsula, indicating the concentration of organic matter is very low and dissolved organic matter of marine origin is considered to be the main component in the study area. As a result of comparing the remote sensing reflectance spectrum with that of coastal waters around the Korean peninsula, coastal waters around Weno Island showed typical CASE-1 water properties. It was possible to understand the marine optical characteristics of coral reef habitats in tropical waters, and it can be used to develop seawater algorithms specialized in the study area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.2
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• pp.69-79
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• 2009

Major and trace elements were analyzed in three core sediments to investigate geochemical characteristics of East Sea sediments and provenance changes during late Quaternary in Ulleung Basin. Comparing with Yellow and South Sea sediments, contents of major elements were generally similar while contents of trace elements were significantly different. Furthermore, within this basin, there were some variabilities in trace element compositions. In the western slope sediments (WS), Mo was enriched over 6 times as much as other sites. On the other hand, Zr, Nb, Hf and Ta were enriched in basin sediments (Basin), and Ca and Cs were enriched in southern slope sediments (SS). After excluding elements derived from biogenic, authigenic and diagenetic origins, the lithogenic elements (K, Ti, Cs, Zr, Nb, Hf and Ta) could be classified into three groups from the comparison of element/Al ratios among cores. The first group consisted of elements (K and Ti) that showed the nearly similar element/Al ratios among three cores. The second group contained Cs which showed significant difference between two slope sediments. The third group elements (Zr, Nb, Hf and Ta) showed highly enriched in basin relative to both slope areas. The depth profiles of metal/Al ratios in basin sediments provided the following interpretation for the compositions of sediment and their variation. From 10,000 yr B.P. to 7,000 yr B.P. two lithogenic components (volcanic ashes and western slope sediments) were mixed and deposited in the basin. After 7,000 yr B.P., however, southern slope sediments were mixed with volcanic ashes and deposited in basin area. This event of source change is nearly close to inflow period of the Tsushima Warm Current to Ulleung Basin. Thus, it might be suggested that element geochemistry in Ulleung basin sediment indicate the change of current system in the study area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.4
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• pp.262-269
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• 2012

We investigated the concentration levels and evaluated the distributions of 17 polychlorinated dibenzo-p-dioxins and furans(PCDD/Fs), 12 dioxin-like polychlorinated biphenyls(DLPCBs) and 24 polybrominated diphenyl ethers (PBDEs) in sediment and organism from various culturing grounds in Korean coast. The levels of PCDD/Fs, DLPCBs, and PBDEs in sediment samples ranged from 0.03 to 2.9(Mean${\pm}$SD, $1.2{\pm}0.89$) pg $WHO_{2005}$-TEQ $g^{-1}$ dry weight(dw), ND(not detected) to 1.1($0.09{\pm}0.19$) pg $WHO_{2005}$-TEQ $g^{-1}$ dw, and ND to 16.6($2.96{\pm}3.53$) ng $g^{-1}$ dw, respectively. Also, the levels of PCDD/Fs, DLPCBs, and PBDEs in culturing organisms ranged from ND to 0.24($0.07{\pm}0.06$) pg $WHO_{2005}$-TEQ $g^{-1}$ wet weight(ww), ND to 0.11($0.04{\pm}0.04$) pg $WHO_{2005}$-TEQ $g^{-1}$ ww, and 0.05 to 0.29($0.13{\pm}0.06$) ng $g^{-1}$ ww, respectively. The levels of total dioxins(PCDD/Fs+DLPCBs) and PBDEs in sediments from East and South sea were four to seven times higher than those from West sea. PCDD/Fs had dominant contribution(mean, 94%) for TEQ concentration in sediment, whereas relatively higher contribution of DLPCBs(33%) were shown in culturing organism than sediment. BDE209 was a dominant congener in both matrix. The concentrations of PCDD/Fs, DLPCBs and PBDEs were in decreasing trends in Korea coasts compared to previous results.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.2
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• pp.125-135
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• 1977

Recently, culture of Undaria pinnatifida, one of the representative esculent sea weed, has been prevailing in tile east and south coasta of Korea and reached the mass culture stage. In this study, compositional quality factors for food were studied and the contributory effects of blanching and pigment fixatives in the quality retention of cultured Undaria pinnatifida are discussed. When the place and time of harvesting were the same, cultured pinnatifida showed scarce difference in the chemical composition comparing to tile naturally grown Undaria pinnatifida, but cultured Undaria pinnatifida shelved a considerable difference depending upon the cultured places. In the chemical composition of Undaria pinnatifida, the alginic acid comprising about $40\%$ of the whole solid materials seemed to be responsible for the compositional puality. The chlorophyll and carotenoid content of the clutured Unaria pinnatifida were considerably lower than that of the naturally grown Undaria pinnatifida and wass inferior in puality by color to the naturally grown one. Dried Undaria pinnatifida contained a considerable amount of amino-N, mannitol, and soluble minerals and it is considered that these components play a great role in the relish effects. It could also be evaluated as a good albuminous source for food science the dried pinnatifida contains about $18\%$ of crude protein. In the analysis of free amino acid composition of dried Undaria pinnatifida, the naturally growm samples showed so what higher levels in all amino acid content than the cultured samples. The contents of theronine, alanine, and glutamic acid were major in quantity wherease histidine cysteine, tyrosine, and phenylalanine were minor. The contents of such amino acids like serine and proline were particularly low or undetectable. The results of amino acid analysis of the acid hydrolysates of dried Undaria pinnatifida in quantity of individual amino acid showed te same pattern as that of free amino acid. It is noticed that Undaria pinnatifida seemed to contain good quality protein since the contents of essential amino acids were considerably higher and uniform. By blanching the fresh sample, the water soluble components brought about cousiderable loss, and, particularly, it was noteworthy that both mannitol and soluble minerals apparently decreased. In the pigment analysis of the dried sample, blanching was effective to retain chlorophyll and carotenoid. The addition of pigment fixatives in blanching solution such as Ca-gluconate, Ca-carbonate, and Ca-hydroxide did not exhibit much effect on the pigment retention except that Ca-carbonate shelved some effect only in the early stage of storage.