• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.684-690
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• 2023

This study was conducted bimonthly from February to December 2021 to reveal the ecology of Sargassum thunbergii in the intertidal zone along the coasts of Korea. Separate surveys on the period of embryo formation were conducted from February 2021 to December 2022. The growth of S. thunbergii began to increase in February, reached a maximum in June, and was at a minimum in October. Air vesicles were formed from February to June, April to August, and February to August on the east, west, and south coasts, respectively. Receptacles were observed from April to June on the east coast, but from April to August on the west and south coasts. The earliest release of embryos was observed in late May 2022 on the south coast, followed by early June on the east and west coasts. The average size of leaves, stems, and air vesicles was maximum on the east coast and minimum on the west coast, whereas leaf and internode intervals were maximum on the west coast and minimum on the east coast. Plant length, biomass, and the number of branches showed maximum values in the south coast and minimum values in the east coast.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.15-19
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• 2007

Mass mortalities of the farmed sea squirt, Halocynthia roretzi, occurred in August, 2006 along the Gyeongbuk coasts of the East Sea without any pathological symptom. Suspecting the No. 10 typhoon, Wukong, which had passed over the relevant locations in the middle of August, 2006 as a culprit of the mortalities, we compared water temperature stratifications of the affected coasts before and after the typhoon. Just prior to the typhoon, cold waters lower than $15^{\circ}C$ were stratified at depths deeper than 10m probably by a persisting upwelling of cold bottom waters. The typhoon enforced water off-coast waters into coasts for 5 days, replacing the cold waters at depths $10{\sim}20m$ which can be justified by Ekman Spiral Effect. The results were an increment of water temperature by $10^{\circ}C$ and more at depths where sea squirts were suspended. The sudden elevation of water temperature might drive the sea squirts under abnormal stress to mass mortality.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.93-96
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• 2009

Unexpected mass mortality has been one of the drawbacks in front of the stable production of Japanese scallop (Patinopecten yessoensis) on the Gangwon coasts of the East Sea. The preliminary data from our routine observation revealed that the mortality appeared to be related to variation of water temperature in the farming site and the degree of the mortality was dependent on scallop strain. The present study performed to verify the preliminary findings exhibited that the mortality was closely related to daily temperature variation rather than monthly variation. Daily temperature variation was particularly damageable to the scallop during the temperature elevation period. Scallops from hatchery seeds (Chinese strain) were more tolerant against the temperature variation over those from wild seeds. The hatchery scallop gain of the temperature tolerance was probably due to their larval experience to higher temperature in the hatchery as well as their maternal genetic acclimation to upper temperature extreme of the Chinese environment which was recently found.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1996.06a
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• pp.299-303
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• 1996

• Journal of The Geomorphological Association of Korea
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• v.25 no.4
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• pp.21-35
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• 2018

The distribution and size of sandy beaches along eastern Korea has a close relationship with the presence of granite rocks. In general, elongated and wide beaches with abundant sands are likely to develop along the coasts where granitic basic rocks comprise the dominant geology or where a large amount of sands are supplied by streams from inland granitic rocks. Small sandy beaches, in contrast, appear in non-granitic rocks (i.e., under sedimentary and/or metamorphic geology). Hence, large beaches are observed continuously along the shore of Gangwon-do, of which coasts consist predominantly of granitic geology. Such continuity declines from Samcheok city to Pohang city. The rock of Gyeonbuk-do is commonly known as sedimentary, deposited between the late Triassic and the early Tertiary Periods. Because few sands are supplied from the upstream areas, sandy beaches unlikely develop along the coasts of the province, only showing a sporadic, discontinuous distribution under Bulguksa granite, granitic gneiss, and some volcanic rocks. Erosion was rarely observed in the beaches where granitic rocks are distributed, whereas merely five beaches seemed to have undergone some level of erosion in non-granitic regions. This is presumably because a larger amount of sands than that which had been eroded away was replenished in areas under granitic geology, while under non-granitic geology having a deficit in sands, no large sandy beaches had formed at first.

• Korean Journal of Remote Sensing
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• v.37 no.1
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• pp.85-95
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• 2021

Recently, as data mining and artificial neural network techniques are developed, analyzing large amounts of data is proposed to reduce the dimension of the data. In general, empirical orthogonal function (EOF) used to reduce the dimension in the ocean data and recently, Self-organizing maps (SOM) algorithm have been investigated to apply to the ocean field. In this study, both algorithms used the monthly Sea level anomaly (SLA) data from 1993 to 2018 around the East Asia Coasts. There was dominated by the influence of the Kuroshio Extension and eddy kinetic energy. It was able to find the maximum amount of variance of EOF modes. SOM algorithm summarized the characteristic of spatial distributions and periods in EOF mode 1 and 2. It was useful to find the change of SLA variable through the movement of nodes. Node 1 and 5 appeared in the early 2000s and the early 2010s when the sea level was high. On the other hand, node 2 and 6 appeared in the late 1990s and the late 2000s, when the sea level was relatively low. Therefore, it is considered that the application of the SOM algorithm around the East Asia Coasts is well distinguished. In addition, SOM results processed by SLA data, it is able to apply the other climate data to explain more clearly SLA variation mechanisms.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.6
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• pp.351-360
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• 1988

Based on historic data of monthly means of sea surface temperatures (SST) for 24 years $(1921\~1944) $ at 23 Korean and Japanese coastal stations in the East Sea (the Japan Sea), we analyzed spatio-temporal characteristics of coastal SST and SST anomalies. The means of SST at Korean coast are higher than those at Japanese coast of the same latitudes, and the annual range of SST at Korean coast are larger than those at Japanese coast. Empirical orthogonal function analysis shows that almost all $(96\%)$ of the SST fluctuations are described by simultaneous seasonal variations. The flurtuations of SST anomalies are small in the Korea Strait and large at the boundaries between the warm and told currents in the basin. The fluctuations of SST anomalies along Korean coast are correlated each other The same is true for SST anomalies along Japanese coast. However, there is only weak correlation between the SST anomalies at Korean coast and those at Japanese coast. Empirical orthogonal function analysis shows that $27\%$ of the coastal SST anomalies in the East Sea are described by simultaneous fluctuations, and $12\%$ of them are described by alternating fluctuations between Korean and Japanese coasts.

• Fisheries and Aquatic Sciences
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• v.24 no.7
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• pp.243-259
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• 2021

The spatial and temporal behaviors and fluctuations of the cold water that appeared in the South East Sea and the East Sea coast from 2016 to 2017 were investigated. The water temperature drop was large in the east coast from April to June and the southeast coast from July to September, and the temperature drop period was longer in the southeast coast. The water temperature fluctuated sensitively to the wind direction, and it gradually decreased in the southwest wind but rose as if jumping in the northeast wind. Wind stress and surface water temperature had an inverse correlation, which was larger in Bukhang-Idukseo, and decreased toward the north of Guryongpo. The cold water appeared mainly in Geojedo-Pohang after 1 to 2 days when the southwest wind was strong, but when the wind became weak, it shrank to the Idukseo (Ulgi-Gampo) and extended into the open sea in a tongue shape. Cold water was distributed only in Samcheok-Toseong in mid-May, Idukseo-Guryongpo and Hupo-Jukbyeon-Samcheok from late May to mid-July, and Bukhang-Idukseo in August-September. The intensity of cold water was greatest in mid-August, and the center of cold water descended from the east coast to the southeast coast from spring to summer. The water temperature fluctuation was dominant at the periods of 1 d and 7-21 d. In wavelet spectrum analysis of water temperature and wind, wind speed increase-water temperature decrease showed phase difference of 12 h in 2 d, 18 h in 3 d, 1.5 d in 4-8 d, and 2-3 d in 8-24 d period. The correlation between the two parameters was large in Geojedo and Namhang, Bukhang-Idukseo, Guryongpo-Jukbyeon, and Samcheok-Toseong. Monitoring stations with high correlation in all periods were generally parallel to the monsoon direction.

• ALGAE
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• v.21 no.1
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• pp.49-59
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• 2006

A total of twenty one species of marine macro-algae were reported from 460 kms long Orissa coast in the east coast of India. Of these 9 species belongs to Chlorophyta, 2 to Phaeophyta and 10 to Rhodophyta. The low species richness compared with southern and western coasts of India was due to lack of rocky and/or coral substratum. Enteromorpha usneoides and Gelidium divaricatum were reported first from India. Enteromorpha linza, E. clathrata, Colpomenia sinuosa, Dictyota dichotoma, Catenella impudica, Compsopogon aeruginosus and Grateloupia lithophila were the new records for Orissa coast.

• Journal of Life Science
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• v.9 no.3
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• pp.262-267
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• 1999

Mitochondrial DNA (mtDNA) polymorphism of the blue mussel (Mytilus edulis) species complex sampled from the east coast of Korean was studied using a partial sequence of COIII gene (336 bp). Samples obtained from three localities on the east coast of Korea revealed four haplotypes with two clearly differentiated mitochondrial clades (termed clades B and E), separated by 4.2% of minimum sequence divergence. This pattern indicates no difference between east and south coasts of Korea. According to population genetic theory on evolutionary characteristics of mtDNA, we concluded that mtDNA introgression from M. edulis to M. gallprovincialis might be a source for mtDNA polymorphism found in mussels on the east coast of Korea.