Eastern Coast Of Korea Research Articles

Computation of Tsunamis in the East (Japan) Sea Using Dynamically Interfaced Nested Model

— A study of 1983 and 1993 tsunami events in the East (Japan) Sea using multigrid dynamically-interfaced finite difference models was performed to produce detailed features of coastal inundations along the eastern coast of Korea. The computational domain is composed of several subregions with different grid sizes connected in parallel or inclined directions. The innermost subregion represents the coastal alignment reasonably well and has a grid size of about 30 meters. Numerical simulations have been performed in the framework of shallow-water equations (linear, as well as nonlinear) over the plane or spherical coordinate system, depending on the dimensions of the subregion. Results of simulations show the general agreements with the observed data of the runup height for both tsunamis. The evolution of the distribution function of tsunami heights is studied numerically and it shows a tendency to the log-normal curve for a long distance from the source.

Bivalve Mollusks in Yeongil Bay, Korea, 1. Introductory Part and Annotated List of Species

An annotated listing of bivalve mollusks collected at 31 sampling sites in Yeongil Bay (eastern coast of Korea) at a depth of 0-52m is presented here. A total of 98 species belonging to 75 genera and 36 families are enumerated; all species are provided with habitat data (bathymetric distribution and bottom sediments character), given separately far living and dead (empty shells) specimens, and some with taxonomic and zoogeographic comments. Fifty-six species are illustrated with photographs. Astarte hakodatensis Yokoyama, 1920 (Astartidae), Nitidotellina pallidula (Lischke 1871) (Tellinidae) and Lyonsia nuculanoformis Scarlato in Volova et Scarlato, 1980 (Lyonsiidae) are found to be new to the Korean fauna, and the genus Salaputium Iredale, 1924 (Crassatellidae) with one species Salapurium Iredale, 1924(Crassatellidae) with one species Salaputium cf. unicum Hayami and Kase, 1993, previously described as being found only from submarine caves in the Ryukyu Islands, is recorded as being found in the East Sea(Sea of Japan) for the first time.

154 Developments on Two Newly Cultivated Species Capsosiphon Fulvescens and Costaria Costata in Korea

In the recent years, there has been increasing demand of nutritive and health foods in Korea. Species diversification is needed in order for seaweed aquaculture to take advantage of these expanding markets. With this in mind, the cultivation of Capsosiphon fulvescens and Costaria costata, was successfully developed. Capsosiphon fulvescens is a filamentous chlorophycean alga growing in the upper littoral regions of the rocky‐shore. It has been used as food in the form of soup with oysters along the Southwestern Coast of Korea. After the development of artificial ¡ seed¡± production (control of light, photoperiod and temperature of parthogenetic gametes), pilot scale, and then large scale, cultivation techniques were established for mass culture of this species. In 2001, the retail price was about $6.2/kg fresh wt with a total production of 770 ton. Costaria costata, a phaeophycean alga, was initially cultivated along the Eastern Coast of Korea. It has now been transplanted successfully to culture grounds along the Southern Coast. The cultivation techniques are very similar to Undaria and Laminaria, ie. long line techniques. It¡¯price is about $1.7/kg fresh wt with total production of 2,000 ton. An overview of these new maricultures technologies that have lead to the successful expansion of the seaweed industry in Korea will be presented.

Influences of light and UV-B on growth and sporulation of the green alga Ulva pertusa Kjellman

The cosmopolitan presence of Ulva spp. is partly due to its great reproductive ability, but relatively little information is available for the radiation conditions triggering reproduction. In the present study, we investigated the effect of photon irradiance, photoperiod, and spectral qualities of light on growth and reproduction of Ulva pertusa. During 8-day culture of discs cut from marginal parts of the thallus of U. pertusa, the size of the thallus discs was greatest at 10 μmol m −2 s −1, while saturation of reproduction occurred at 30 μmol m −2 s −1. The minimum photon irradiance allowing growth and reproduction was 5 and 10 μmol m −2 s −1, respectively. Rapid increases in the size and subsequent initiation of sporulation were observed in samples transferred to saturating irradiance from 5 μmol m −2 s −1 or darkness for 9 days. When exposed to different photoperiods (8:16-, 12:12-, 16:8-h LD and continuous light regimes) combined with different photon irradiances (10 and 100 μmol m −2 s −1), U. pertusa thallus showed that the thallus size attained at the low irradiance was similar in daylengths longer than 12 h per day, while the surface area increased in parallel with increasing light duration at the high irradiance. The degree of sporulation at 10 μmol m −2 s −1 varied, ranging from no sporulation in 8:16-h LD to 80% in 16:8-h LD and continuous light. On the other hand, there was no remarkable difference in the degree of sporulation between the photoperiods except for slightly smaller percentage sporulation in 8:16-h LD at 100 μmol m −2 s −1. At 5 μmol m −2 s −1, the growth of U. pertusa was markedly lower in green than in blue or red light, but there was no sporulation in any spectral quality. The degree of sporulation at 20 μmol m −2 s −1 was almost twice as much in blue or red as in green light. The size of plants irradiated with 1.0 W m −2 of UV-B for 20–40 min increased by 18–21% relative to control, whereas higher UV irradiance caused inhibition of growth. There was a significantly lower incidence of sporulation in UV-B-irradiated plants with the degree of reduction being greater in those exposed to higher UV doses. The total biologically effective UV-B dose for 50% inhibition of sporulation was 0.085 Dose eff kJ m −2. The time required to achieve 50% inhibition would be longer than 13 h at depths below 1 m in Ahnin coastal waters. The vertical attenuation coefficient of PAR ( λ=400–700 nm) and UV-B ( λ=300–320 nm) in April 1998 at Ahnin on the eastern coast of Korea was 0.21 m −1 for K PAR and 0.54 m −1 for K UV-B. A large reduction of light quantity and rapid disappearance of blue wavelength occurred by shading from overlying thalli. Percentage inhibition of sporulation was only 14–18% at 150–200 μmol m −2 s −1 compared with 70% at 10 μmol m −2 s −1, when plants were incubated under different irradiances of PAR immediately after UV-B exposures. These different photoadaptive strategies for sporulation may in part account for the great ecological success of U. pertusa.

동적결합둥지형 모형에 의한 동해안 쓰나미 시뮬레이션

상세한 지진해일 범람 현상을 규명하기 위하여 수립된 전회의 동적결합 차분 모형(Choi et al.)이 1983년 동해중부지진에 의한 지진해일 연구를 위해 우리나라 동해안 전역에 적용되었다. 계산영역은 격자의 크기가 다른 몇 개의 둥지영역이 평행하거나 경사가 진 방향으로 연결되어 구성되어 있다. 제일 안쪽의 둥지 영역은 해안을 따라 순차적으로 16영역으로 구성되었으며, 격자간격은 약 30m이다. 천수방정식(선형과 비선형)이 적용된 수치 시뮬레이션은 둥지영역의 격자크기에 따라 직각 또는 구면좌표계가 채택되었으며, 평행 및 경사 접합이 제일 안쪽의 둥지형 모형에 적용되었다. 시뮬레이션에 의한 결과는 지진해일 사상에 대한 처오름 높이의 관측치와 잘 일치하였다. 지진해일고 분포곡선의 개선이 수치적으로 연구되었으며, 지진원으로부터 거리가 먼 경우에는 대수정규분포를 따르는 경향을 보인다. A dynamically-interfaced multi-grid finite difference model for simulation of tsunamis in the East Sea(Choi et al.) was established and further applied to produce detailed feature of coastal inundations along the whole eastern coast of Korea. The computational domain is composed of several sub-regions with different grid sizes connected in parallel of inclined directions with 16 innermost nested models. The innermost sub-region represents the coastal alignment reasonably well and has a grid size of about 30 meters. Numerical simulations have been performed in the framework of shallow-water equations(linear, as well as nonlinear) over the plane or spherical coordinate system, depending on the dimensions of the sub-region. Results of simulations show the general agreements with the observed data of run-up height for both tsunamis. The evolution of the distribution function of tsunami heights is studied numerically and it is shown that it tends to the log-normal curve for long distance from the source.

Holocene environmental changes of the Hwajinpo Lagoon on the eastern coast of Korea

Lithologic and geochemical data of a core from the Hwajinpo Lagoon, located on the eastern coast of Korea, provided the evolutionary history of the lagoon related to Holocene sea-level changes of the East Sea (Sea of Japan). Grain size analysis, water content analysis, and soft X-ray analysis of core samples were used to reconstruct sedimentary environments, as were total organic carbon, C/N, S and C/S chemical records. Assemblages of mollusc and diatom remains also provided paleoenvironmental information. The reconstruction of paleoenvironments from these multi-proxy data allows the establishment of an evolutionary model of the Hwajinpo Lagoon. The environmental changes of the Hwajinpo Lagoon can be divided into seven different depositional facies: (l) Exposed basement rock; (2) Estuarine; (3) Stagnant brackish lagoon (isolated); (4) Oxic condition lagoon (organic activity); (5) Fresh water lake; (6) Oxic brackish lagoon (recent condition); (7) Prograding river delta. These environmental changes can be related to sea-level change during the Holocene. The trends of sea-level change in the Hwajinpo Lagoon from this study can be compared to those of the Japanese coastal areas located on the other side of the East Sea such as Lakes Shinji and Nakaumi.

P-18 韓半島東海岸,花律浦・松池湖のボーリングコアによる完新世堆積環境解析(9. 最終間氷期以降の東アジアの気候・環境変動,ポスターセッション,一般発表)

P-18 韓半島東海岸,花律浦・松池湖のボーリングコアによる完新世堆積環境解析(9. 最終間氷期以降の東アジアの気候・環境変動,ポスターセッション,一般発表)

The germling growth of Enteromorpha intestinalis (Chlorophyta) in laboratory culture under different combinations of irradiance and salinity and temperature and salinity

The effects of environmental factors on germling growth in Enteromorpha intestinalis (L.) Link (Ulvales, Chlorophyta) from the eastern coast of Korea (35°29′N, 129°27′E) were examined in laboratory culture at different combinations of irradiance, salinity, and temperature. Maximum growth rate was at 250 μmol m−2 s−1 and 24‰ in combinations of irradiance and salinity and at 15°C and 24‰ in combinations of temperature and salinity. The germlings survived over a wide range of irradiance, but showed a rather low irradiance optimum. The growth responses of germlings grown under a wide range of temperature and salinity were compared with seasonal occurrence and vertical distribution patterns in the survey area. The results suggest that E. intestinalis follows an annual growth cycle with high growth rate of germlings during spring and autumn. A broad environmental tolerance and rapid growth rate provide the germlings with a means of survival throughout the intertidal.

COPEPODID STAGES OF HEMICYCLOPS CTENIDIS HO AND KIM, 1990 (CLAUSIDIIDAE), A POECILOSTOMATOID COPEPOD ASSOCIATED WITH A POLYCHAETE

ABSTRACT Copepodid stages and adults of Hemicyclops ctenidis, a poecilostomatoid copepod symbiotic with a polychaete, were discovered in a brackish lagoon located on the eastern coast of Korea. The Saphirella-like first copepodids were collected simultaneously from both water and host in the same location. This finding substantiates previous authors' contentions that the Saphirella occurring in plankton samples are young forms of poecilostomatoids. Features occurring during copepodid development are described. This is the first record of the entire copepodid stages of Hemicyclops, one of the most primitive poecilostomatoids.

Application of a variational inverse model to determine a wintertime circulation in the East Sea of Korea

Using a variational inverse model, a wintertime ocean circulation is obtained in the East Sea of Korea bounded by transects of 34° N, 38° N in latitude and 132° E in longitude and coastlines. The hydrographic data observed by FRDAK (Fisheries Research and Development Agency of Korea) are used for determining the vertical structure and also used as data constraints. In the current study, the model was constrained only by the geostrophic balance and bottom topography. Preliminary model results showed that the vertical distributions of temperature in February 1983 were homogeneous in the coastal region south of 35°30′ N and that the extension of cold water mass along the eastern coast of Korea was noticed in the northern part of the study area. Meandering northward flows with the scale of 150 km are also observed to be dominant in the surface layer (10–100 m).

Decreased birth weight after prenatal exposure to wildfires on the eastern coast of Korea in 2000.

In April 2000, a series of wildfires occurred simultaneously in five adjacent small cities located on the eastern coast of Korea. These wildfires burned approximately 23,794 hectares of forestland over several days. We investigated the effects of prenatal exposure to the by-products generated by wildfire disasters on birth weight. Birth weight data were obtained for 1999-2001 from the birth registration database of the Korean National Statistical Office and matched with the zip code and exposed/unexposed pregnancy week for days of the wildfires. Generalized linear models were then used to assess the associations between birth weight and exposure to wildfires after adjusting for fetal sex, gestational age, parity, maternal age, maternal education, paternal education, and average exposed atmospheric temperature. Compared with unexposed pregnancies before and after the wildfires, mean birth weight decreased by 41.4 g (95% confidence interval [CI], -72.4 to -10.4) after wildfire exposure during the first trimester, 23.2 g (95% CI, -59.3 to 13.0) for exposure during the second trimester, and 27.0 g (95% CI, -63.8 to 9.8) during the third trimester. In the adjusted model for infants exposed in utero during any trimester, the mean birth weight decreased by 32.5 g (95% CI, -53.2 to -11.7). We observed a 1% reduction in birth weight after wildfire exposure. Thus, exposure to by-products generated during a wildfire disaster during pregnancy may slow fetal growth and cause developmental delays.