• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.608-615
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• 2023

The morphological features of germling cells were examined to identify an unspecified resting cyst (described as Cochlodinium cf. polykrikoides-like resting cyst) in the Korean coastal area. LSU rRNA gene sequences were also obtained from a strain established from the germling cells. The resting cysts isolated from Korean coastal sediment were characterized as being brown in color, having a large dark-red body, and fibrous lobed ornaments. The germling cells were ellipsoidal with an irregular outline and had an open comma-shaped ASC (apical structure complex), a wide and deep cingulum, and a deep sulcus. These morphological features were consistent with those of previously described harmful dinoflagellate Pseudocochlodinium profundisulcus. The molecular phylogeny revealed that the germling cells and P. profundisulcus were conspecific. Based on these morphological and phylogenetic data, this study documents the occurrence of P. profundisulcus in a Korean coastal area for the first time.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.6_2
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• pp.529-538
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• 2013

Coastline is the most dynamic part of seascape since its shape is affected by various factors. Coastal zone is an area with immense geological, geomorphological and ecological interest. Monitoring coastal change is very important for safe navigation, coastal resource management. This paper shows a result of monitoring coastal morphological changes using Remote Sensing and GIS. Study was carried out to obtain intensity of erosion, deposition and sand bar movement in the Red River Delta. Satellite images of ALOS/AVNIR-2 and Landsat were used for the monitoring of coastal morphological changes over the period of 1975 to 2009. Band rationing and threshold technique was used for the coastline extraction. Tidal levels at the time of image acquisition varied from -0.89m to 2.87m. Therefore, coastline from another image at a different tidal level in the same year was considered to get the corrected coastline by interpolation technique. A series of points were generated along the coastal line from 1975 image and were established as reference points to see the change in later periods. The changes were measured in Euclidean distances from these reference points. Positive values represented deposition to the sea and negative values are erosion. The result showed that the Red river delta area expanded to the sea 3500m in Red river mouth, and 2873m in Thai Binh river mouth from 1975 to 2009. The erosion process occurred continuously from 1975 up to now with the average magnitude 23.77m/year from 1975 to 1989 and 7.85m/year from 2001 to 2009 in Giao Thuy area. From 1975 to 2009, total 1095.2ha of settlement area was eroded by sea. On the other hand, land expanded to the sea in 4786.24ha of mangrove and 1673.98ha of aquaculture.

• Journal of Coastal Disaster Prevention
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• v.6 no.3
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• pp.111-120
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• 2019

In coastal morphological modelling, there are a number of input factors: wave height, water depth, sand particle size, bed friction coefficients, coastal structures and so forth. Measurements or estimates of these input data may include uncertainties due to errors by the measurement or hind-casting methods. Therefore, it is necessary to consider the uncertainty of each input data and the range of the uncertainty during the evaluation of numerical results. In this study, three uncertainty factors are considered with regard to the prediction of coastal erosion in Ilsan beach located in Ilsan-dong, Ulsan metropolitan city. Those are wave diffraction effect of XBeach model, wave input scenario and the specification of the coastal structure. For this purpose, the values of mean wave direction, significant wave height and the height of the submerged breakwater were adjusted respectively and the followed numerical results of morphological changes are analyzed. There were erosion dominant patterns as the wave direction is perpendicular to Ilsan beach, the higher significant wave height, and the lower height of the submerged breakwater. Furthermore, the rate of uncertainty impacts among mean wave direction, significant wave height and the height of the submerged breakwater are compared. In the study area, the uncertainty influence by the wave input scenario was the largest, followed by the height of the submerged breakwater and the mean wave direction.

• Journal of the Korean association of regional geographers
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• v.10 no.3
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• pp.667-681
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• 2004

This research is aimed to investigate the relationship of the effective wind velocity and the morphological change in coastal dune at Sindu-ri in Korea. Sediment flux was estimated by the measurement of elevation change along eight transects deployed in the study area from July 1999 to July 2000. The results of this study indicated that. first. based on the occurrence of morphological change and winds effective for sand movement. two distinct seasons were identified: a season of deposition and that of erosion. During the depositional season, spanning from November to April, effective winds were dominant and sand accumulation occurred mainly in foredunes and sequentially in dune plains. During the erosional season, from May through October, volume change was small and erosion or sand loss occurred mostly at the dunefoot of foredunes. Secondly, the research revealed that the sediment budget of Sindu coastal dune turned out to be surplus on the whole, but there are some regional differences. Deficit budgets were observed partly in secondary dunes. The utmost northern part of Sindu coastal dune was provided with abundant sand, whereas the central and northern parts were poorly supplied.

• Journal of Ocean Engineering and Technology
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• v.37 no.2
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• pp.68-79
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• 2023

Even though submerged breakwater reduces incident wave energy, it redistributes the coastal area's wave-induced current, sediment transport, and morphological change. This study examines the coastal hydrodynamics and the morphological response of a wave-dominated beach with submerged breakwaters installed through field observation and quasi-3D numerical modeling. The pre-and post-storm bathymetry, water level, and offshore wave under storm forcing were collected in Bongpo Beach on the East coast of Korea and used to analyze the coastal hydrodynamic response. Four vertically equidistant layers were used in the numerical simulation, and the wave-induced current was examined using quasi-3D numerical modeling. The shore normal incident wave (east-northeast) generated strong cross-shore and longshore currents toward the hinterland of the submerged breakwater. However, the oblique incident wave (east-southeast) induced the southeastward longshore current and the sedimentation in the northeast area of the beach. The results suggested that the incident wave direction is a significant factor in determining the current and sediment transport patterns in the presence of the submerged breakwaters. Moreover, the quasi-3D numerical modeling is more appropriate for estimating the wave transformation, current, and sediment transport pattern in the coastal area with the submerged breakwater.

• Korean Journal of Ichthyology
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• v.22 no.4
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• pp.293-296
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• 2010

Morphological characters of Zanclus cornutus are redescribed in detail based on a single specimen (89 mm SL) collected from the coastal waters of Jeju Island, Korea. This species is characterized by a protruding mouth, a short spine in front of each eye, and the third spine of dorsal fin prolonged into a long filament.

• ALGAE
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• v.24 no.4
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• pp.195-203
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• 2009

Most Skeletonema species have been identified under the name of S. costatum. To assess the morphological species diversity in the genus Skeletonema, we surveyed the nine localities in the coastal waters of South Korea. The light microscopy (LM) and scanning electron microscopy (SEM) observations in this study showed that ultrastructural features of genus Skeletonema discriminated among four species: S. dohrnii Sarno & Kooistra, S. marinoi Sarno & Zingone, S. subsalsum (Cleve) Bethge, and S. tropicum Cleve. In S. dohrnii, cell diameters were 3-6 ${\mu}m$ and the pervalvar axes were 13-19 ${\mu}m$. One or two partial chloroplasts were visible in a cell. Cells of S. marinoi were 4-10 ${\mu}m$ and the pervalvar axes were 8-18 ${\mu}m$. Each cell contained one chloroplast. Cells of S. subsalsum which contained 1-2 chloroplasts were 8-13 ${\mu}m$ and the pervalvar axes were 11-20 ${\mu}m$. Cells of S. tropicum were 10-18 ${\mu}m$ and the pervalvar axes were 4-9 ${\mu}m$. 2-4 chloroplasts were seen in each cell. Tip width of fultoportula in S. dohrnii and S. marioni was flared and flat, but that in S. subsalsum and S. tropicum was narrow. Morphological groups among them, S. dohrnii and S. marinoi were the most widely distributed in all seasons, while S. tropicum was only occurred in a summer season.

• ALGAE
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• v.23 no.1
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• pp.15-29
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• 2008

Many species in Gymnodiniales, which are unarmored dinoflagellates, are responsible for marine algal blooms and some of them have potent toxin in the cell. Their taxonomy has so far been well-defined, and several genera (e.g. Akashiwo, Gymnodinium, Karenia) have recently been re-described. In Korea, few works have been carried out on their taxonomical and molecular studies. This study focused on comparison of both morphological and molecular characteristics of five unarmored dinoflagellates on Korean coastal water: Akashiwo sanguinea, Cochlodinium polykrikoides, Gymnodinium catenatum, Gymnodinium impudicum and Karenia aureolum (=K. mikimotoi). Morphological characteristics observed here was in good accordance with the original descriptions of individual species. In addition, none of difference was found in morphological comparisons between the Korean and foreign strains. Furthermore, molecular analysis showed that the SSU rDNA sequences were generally identical according to each species. In some distinct features, A. sanguinea, which has generally the same morphological features, were divided into two groups: one was Korean isolates including European isolates, the other was American isolates. In the two groups, the nucleus was positioned differently: middle of the cells in the Korean isolates (GnSg02, GnSg03), near the epicone in American isolates (CCMP1593, CCMP1837). In addition, this was strongly supported by phylogenetic analysis, inferred from the SSU rDNA sequences. K. aureolum (GrAr01) was corresponded to European G. aureolum (=K. mikimotoi) in shape and position of nucleus, chloroplast, however, which is similar to K. digitata in view of having a finger-like sulcus. This was in good agreement with phylogenetic study of these species. G. catenatum have identical morphology except the ridge location, and their genotype of SSU rDNA was also identical to GenBank data of the same species. From this study, we found that the five Korean unarmored dinoflagellates are identical morphological characteristics and genotype to each species of foreign isolates.

• Research in Plant Disease
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• v.27 no.1
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• pp.45-47
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• 2021

Damping-off symptoms were frequently observed on young plants of coastal hogfennel (Peucedanum japonicum) grown in a farmer's vinyl greenhouse located in Goseong, Gangwon Province, Korea during a disease survey in June 2019. Incidence of the diseased plants was 50-70% in the vinyl greenhouse investigated during the disease survey. Eight isolates of Rhizoctonia sp. were obtained from the diseased plants. All the isolates were identified as Rhizoctonia solani AG-4 based on the morphological characteristics and anastomosis test. Three isolates of R. solani AG-4 were tested for pathogenicity on coastal hogfennel by artificial inoculation. All the tested isolates induced damping-off symptoms on the inoculated plants. The symptoms were similar to those observed in the farmer's vinyl greenhouse investigated. This is the first report of R. solani AG-4 causing damping-off in coastal hogfennel.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.667-670
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• 2014

Six adult fish of Laemonema nana, belonging to the family Moridae, were collected in a bottom trawl in the southern coastal waters of Korea. These specimens were characterized by having 46-52 second dorsal fin rays (vs. 57-67 for Lotella phycis and 68 for Physiculus japonicus), two pelvic fin rays (vs. 9 for L. phycis and 6-7 for P. japonicus), and lateral line descending abruptly below the anterior part of the second dorsal fin.