• Journal of Life Science
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• v.13 no.3
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• pp.359-364
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• 2003

The seaweed Porphyra pseudolinearis as a dominant species grows at upper of the intertidal zone of the East Sea from October to March. Vegetative cells have not matured during October when observed with naked eye and microscope. In the middle of November, although it didn't distingush between female and male gametophytes by eye, it showed antheridium and carpogonium when observed vertical section under microscope. From early December, It could be distinguished female and male gametophytes clearly. From Feburary it showed shorted length of thalli by release of spermatangia and carposporangia as maturation. At early March, the colar has been decaeded and side of thalli has been melted, completed of release of spermatia. At the end of December, the average length and width of female thalli were 149.9$\pm$5.6mm and 22.2$\pm$2.3mm, respectively. The length and width of male thalli were 149.9$\pm$9.4mm and 20.7$\pm$1.8mm. At the end of January, the average length and width of female thalli were 94.6$\pm$6.4mm and 29.1mm$\pm$5.1, respcetively. The length and width of male thalli were 107.8$\pm$7.3mm and 25.9$\pm$0.9mm. From this period lengths of female and male thalli have already been shortned by the release of spermatia and carpogonia.

• The Korean Journal of Malacology
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• v.22 no.1 s.35
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• pp.13-22
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• 2006

Gonadosomatic index (GSI), oogenesis and reproductive cycle of Glossaulax didyma were investigated by the cytological histological obserbations and morphometric data. Samples were collected monthly from the intertidal zone of Biin Bay, Seocheon, Korea, for one year. Monthly variations in the GSI showed similar patterns with gonadal development. In the early vitellogenic oocyte, the Golgi complex and mitochondria were invovled in the formation of lipid droplet and yolk precursor. In the late vitellogenic oocytes, the rough endoplasmic reticulum and multivesicular bodies were involved in the formation of profeid yolk granules in the cytoplasm. A mature yolk granule was composed of three components: main body (central core), superficial layer, and the limiting membrane. The spawning season was from early June to late August, and the main spawning occurred between July and August when the seawater temperature was above $19^{\circ}C$. The female reproductive cycle can be classified into five successive stages: early active stage (December to February), late active stage (February to March), ripe stage (April to July), spawning stage (June to August), recovery stage (August to November). Fully mature oocytes were approximately $250-270{\mu}m$ in diameter.

• Journal of Life Science
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• v.29 no.2
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• pp.152-157
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• 2019

Porphyra yezoensis is a red algal species in the genus Porphyra. The phenetics and genetic diversity of four populations of P. yezoensis in Korea were reconstructed using random amplified polymorphic DNA (RAPD) markers. Overall, 55 fragments were generated among the tested P. yezoensis array with 20 OPERON primers. A total of 30(54.5%) of these bands were polymorphic. The OPA-18-02 band was amplified in the samples of Nakdong population and absent in them of other three populations. The OPA-20-02 band was only amplified in the Seocheon population. Both bands exhibited distinctive patterns in specific populations. The effective number of alleles per locus (Ae) ranged from 1.161 to 1.293 with a mean of 1.366. The Seocheon population had a high expected diversity (0.163). The Nakdong population was an isolated endemic and intertidal zone. Thus the narrow distributed Nakdong population had a low expected diversity (0.092). Shannon's index of phenotypic diversity (I) of the Seocheon population (0.238) was the highest among all populations. Total genetic diversity ($H_T$) varied between 0.132 for OPA-02 and 0.420 for OPA-19. The interlocus variation of genetic diversity ($H_S$) was 0.059 for OPA-18 and 0.339 for OPA-19. On a per locus basis, the proportion of total genetic variation due to differences among populations ($G_{ST}$) ranged from 0.012 for OPA-11 to 0.762 for OPA-18 with a mean of 0.415, indicating that 42% of the total variation was found among these populations. In an assessment of the proportion of diversity present within this species, 58.5% (100%-41.5%) of genetic variation resided within the populations studied. The Nm was estimated to be low (0.705).

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1527-1539
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• 2022

As coastal erosion of the east coast is accelerating, the need for scientific and quantitative coastal erosion monitoring technology for a wide area increases. The traditional method for observing changes in the coast was precision monitoring based on field surveys, but it can only be applied to a small area. The airborne bathymetric Light Detection And Ranging (LiDAR) system is a technology that enables economical surveying of coastal and seabed topography in a wide area. In particular, it has the advantage of constructing topographical data for the intertidal zone, which is a major area of interest for coastal erosion monitoring. In this study, time series analysis of coastal seabed topography acquired in Aug, 2021 and Mar. 2022 on the littoral cell GW36 in Gangwon was performed using the Seahawk Airborne Bathymetric LiDAR (ABL) system. We quantitatively monitored the topographical changes by measuring the baseline length, shoreline and Digital Terrain Model (DTM) changes. Through this, the effectiveness of the ABL surveying technique was confirmed in coastal erosion monitoring.

• Korean Journal of Ichthyology
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• v.33 no.1
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• pp.1-7
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• 2021

Using stereo, light, and scanning electron microscopes, we researched the anatomical and histological structure of Chaenogobius gulosus's olfactory organ and compared it to those of sympatric gobies Luciogobius guttatus and Favonigobius gymnauchen. Results revealed the following common characteristics: i) tubular anterior nostril (AN) and flat posterior nostril (PN), ii) a single longitudinal lamella, iii) two accessory nasal sacs (ANS, ethmoidal and lacrimal), iv) abundant sensory epithelium lymphatic cells (LC), v) an eosinophil cell, and vi) a ciliary length a quarter of the knob diameter in the olfactory receptor neuron (ORN). Some characteristics are specific to C. gulosus and different from the other two gobies: i) 0.5~1.0 mm AN and 0.2~0.5 mm PN (vs. 0.2~0.3 mm and 0.2~0.3 mm in L. guttatus; 0.2~0.4 mm and 0.1~0.3 mm in F. gymnauchen), ii) two ANS (vs. absence in L. guttatus; two in F. gymnauchen), iii) abundant LC (vs. low in L. guttatus and F. gymnauchen), iv) low density non-sensory cilia on the lamellar surface (vs. high in L. guttatus; low in F. gymnauchen), and v) a quarter ciliary length to knob diameter ratio in the ORN (vs. mixture of a quarter to equal ratio in L. guttatus; two or three times in F. gymnauchen). From these results, we confirmed the C. gulosus olfactory organ has adapted anatomically and histologically to the sand-rock tidal zone.

• ALGAE
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• v.38 no.2
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• pp.141-150
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• 2023

Light quality is a common environmental factor which influences the metabolism of biochemical substances in algae and leads to the response of algal growth and development. Pyropia yezoensis is a kind of economic macroalgae that naturally grows in the intertidal zone where the light environment changes dramatically. In the present study, P. yezoensis thalli were treated under white light (control) and monochromatic lights with primary colors (blue, green, and red) for 14 days to explore their physiological response to light quality. During the first 3 days of treatment, P. yezoensis grew faster under blue light than other light qualities. In the next 11 days, it showed better adaptation to green light, with higher growth rate and photosynthetic capacity (reflected by a higher rETR_max = 61.58 and E_k = 237.78). A higher non-photochemical quenching was observed in the treatment of red light than others for 14 days. Furthermore, the response of P. yezoensis to light quality also results in the difference of photosynthetic pigment contents. The monochromatic light could reduce the synthesis of all pigments, but the reduction degree was different, which may relate to the spectral absorption characteristics of pigments. It was speculated that P. yezoensis adapted to a specific or changing light environments by regulating the synthesis of pigments to achieve the best use of light energy in photosynthesis and premium growth and metabolism.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.5
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• pp.727-743
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• 1996

To know the floristic composition, vortical distribution and community structure of marine benthic algae inhabiting in the intertidal and subtidal zones of Yongil Bay, east coast of Korea, the study has performed using the quadrat method along a transect line from July, 1995 to June, 1996. In this area, a total of 144 species including 2 new red algae to Korea was found: 5 blue-green, 18 green, 20 brown and 101 red algae. The representative species throughout the year were Ulva pertusa, Gelidium amansii and Symphyocladia latiuscula. Dominant species were Sargassum thunbergii in spring, U. pertusa in summer and autumn. In winter, Chondrus ocellatus and Monostroma grevillei occurred dominantly. The standing crop exhibited mean value as $185.8g/m^2$ dry weight. Maximum value was recorded in spring $(267.3g/m^2)$ and minimum was observed in winter $(93.7g/m^2)$. Shannon's species diversity (H') and evenness (J') as maximum value were recorded in spring, whereas minimum values were shown in winter. Vertical distribution, rerognized by cluster analysis based on relative coverage of the species, could be divided into two or three algal groups except spring. In general, green algae (M. grevillei, Capsosiphon fulvescens, U. pefusa, Enteromorpha compressa) and brown algae (Sargassum fulvellum, S. thunbergii) were represented in the upper and middle zone and red algae (G. amansii, C. ocellatus, S. latiuscula, Crateloupia okamurae, Pachymeniopsis eilliptica) in the lower zone. The algal community varied according to season and environmental conditions. Particularly, seasonal variation of vortical distribution seemed to be affected primarily by water temperature. Also seasonal tidal level and tolerance of algal species to desiccation appeared to be associated with it in this area.

• Economic and Environmental Geology
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• v.54 no.6
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• pp.717-731
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• 2021

We analyzed the characteristics of the habitat environment for the Seonam study area in Ulsan, the southern shore of the East Sea using bathymetry and seafloor environment data. The depth of the study area ranges from about 0 m to 23 m. In the west of the study area, the water depth is shallow with a gentle slope, and the water depth becomes deeper with a steep slope in the east. Due to the right-lateral strike-slip faults located in the continental margin of the East Sea, the fracture surfaces of the seabed rocks are mainly in the N-S direction, which is similar to the direction of the strike faults. Three seafloor types (conglomeratic-grained sandy, coasre-graiend sandy, fine-grained sandy) and rocky bottom area have been classified according to the analyses of the bathymerty, seafloor image, and surface sediment data. The rocky bottom areas are mainly distributed around Seaoam and in the northern and southern coastal area. But the intermediate zone between Seonam and coastal area has no rocky bottom. This intermediate area is expected to have active sedimentation as seawater way. The sandy sediments are widely distributed throughout the study area. Underwater images and UAV images show that Cnidarians, Brachiopods, Mollusks are mostly dominant in the shallow habitat and various Nacellidae, Mytilidae live on the intertidal zone around Seonam. Annelida and Arthropod are dominant in the sandy sediments. The distribution of marine organism in the study area might be greatly influenced by the seafloor type, the composition and particle size distribution of the seafloor sediments. The analysis of habitat environment mapping with bathymetry, seafloor data and underwater images is supposed to contribute to the study of the structure and function of marine ecosystem.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.1
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• pp.63-70
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• 1999

The optimum sampling area which can be applied to the benthic community study is estimated from large survey data in the Songdo tidal flat and subtidal zone of Youngil Bay, Korea. A total of 250 samples by 0.02 $m^2$ box corer for the benthic fauna in Songdo tidal flat and 50 samples by 0.1 $m^2$ van Veen grab in Youngil Bay were taken from the total sampling area of 5 $m^2$. It was assumed that the sampling area could contain sufficient information on sediment fauna, if cumulative number of species, ecological indices, and similarity index by cluster analysis reflect the similarity level of 75% to those found at total sampling area (5 $m^2$). A total of 56 and 60 species occurred from Songdo tidal flat and Youngil Bay, respectively. The cumulative curve of the species number ($N_{sp}$) as a function of the sampling area (A in $m^2$ ) was fitted as $N_{sp}=37.379A^{0.257}$ ($r^2=0.99$) for intertidal fauna and $N_{sp}=40.895A^{0.257}$ ($r^2=0.98$) for subtidal fauna. Based on these curves and 75% of similarity to the total sampling area (5 $m^2$), the optimum sampling area was proposed as 1.6 $m^2$ for the intertidal and 1.5 $m^2$ for the subtidal fauna. Ecological indices (species diversity, richness, evenness and dominance indices) were again calculated on the basis of species composition in differently simulated sample sizes. Changes in ecological indices with these sample sizes indicated that samplings could be done by collecting fauna from < 0.5 $m^2$-1.5 $m^2$ on the Songdo tidal flat and from < 0.5 $m^2$-1.2 $m^2$ in Youngil Bay. Changes in similarity level of all units of each simulated sample size showed that sampling area of 0.3 $m^2$ (Songdo tidal flat) and 0.6 $m^2$ (Youngil Bay) should be taken to obtain a similarity level of 75%. In conclusion, sampling area which was determined by cumulative number of species, ecological indices and similarity index by cluster analysis could be determined as 1.5 $m^2$ (0.02 $m^2$ box corer, n=75) for Songdo tidal flat and 1.2 $m^2$ (0.1 $m^2$ van Veen grab, n=12) for Youngil Bay. If these sampling areas could be covered in the field survey, population densities of seven dominant species comprising 68% of the total faunal abundance occurring on Songdo tidal flat and six species comprising 90% in Youngil Bay can be estimated at the precision level of P=0.2.

• The Korean Journal of Malacology
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• v.23 no.2
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• pp.189-198
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• 2007

The reproductive cycle, egg capsules in the egg-mass, first sexual maturity, and sex ratio of the bladder moon, Glossaulax didyma ($R\ddot{o}ding$) were investigated. The gastropods collected from the intertidal zone of Biin Bay, Seocheon, Korea were studied by using histological analysis and morphometric data. The gonadosomatic index (GSI) of females and males began to increase in March and reached maximum in May. Then their values sharply decreased from late in May to August due to spawning. The condition index (CI) began to increase in February and reached maximum in May, then gradually declined in the spawning period. The CI calculated for determination of the spawning period was coincided with changes in the GSI and gonadal phases. Spawning occurred between late in May to August in females and early in May to August in males. Spawning peak was observed between July and August when the seawater temperature rose to 19 $^{\circ}C$. Reproductive cycle with the gonadal development phases of this species can be divided into five successive stages in females and four in males: in females, early active stage (December to February), late active stage (February to March), ripe stage (April recovery stage (August to November); in males, active stage (December to March), ripe stage (March to July), copulation stage (early May to August), and recovery stage (August to January). Fully matured oocytes were approximately 250-270 ${\mu}m$ in size. The egg-mass was a hat in shape, and a number of egg capsules were found in an egg-mass. An egg capsule was 0.53-0.57 mm in size. An embryo (veliger larva) hatched from an egg capsule. Percentage of first sexual maturity in females and males were over 50% for individuals that are 40.1-45.0 mm in shell radius, and 100% for those that are over 45.1 mm. The sex ratio of female to male was significantly different from 1:1 $(x^2\;=\;57.22,\;p\;<\;0.05)$.