• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.3
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• pp.124-141
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• 1998

The objectives of this study are to investigate the trace (minor) elemental and isotopic compositions of calcitic skeletons, such as barnacle, echinoid, branching and encrusting calcareous algae and oyster, from the eastern coast of Korean peninsula and Cheju Island, and to compare their variations with latitude, that is, the temperature of ambient seawater at which the skeletons grew. Articulated and encrusting red algae are composed of high-Mg calcite (7-21 mol% $MgCO_3$). Echinoids are also composed of high-Mg calcite (7-15 mol% $MgCO_3$). Whereas barnacles are composed of low-Mg calcite (1-5 mol% $MgCO_3$). The Mg compositions of articulated red algae, barnacle and oyster tend to increase with increasing water temperature, whereas those of encrusting red algae and echinoid do not show any trend. Sr compositions of articulated red algae, echinoid and barnacle tend to decrease with increasing water temperature, whereas those of encrusting red algae and oyster do not show any trend. Mn compositions of articulated red algae and encrusting red algae decrease with an increase of water temperature, whereas those of echinoid and barnacle do not show any trend. Fe compositions of articulated red algae tend to decrease with increasing water temperature, whereas those of encrusting red algae and oyster increase. Fe compositions of echinoid and barnacle do not show any trend with water temperature variations. Ba compositions of echinoid and low-magnesium calcitic skeletons do not show any trend with water temperature variations. Ba compositions of articulated red algae tend to decrease with increasing water temperature, whereas those of encrusting red algae increase. Cd and Pb compositions of all the skeletons tend to increase with increasing water temperature. Cu compositions of encrusting red algae increase with increasing water temperature, whereas articulated red algae, echinoid, barnacle and oyster do not show any trend. Zn compositions of high-magnesium calcitic skeletons and low-magnesium calcitic skeletons do not show any trend. Estimated water temperatures from oxygen isotopic data of all the skeletons except for the barnacle arc higher than the range of temperature of the shallow seawater of the East Sea and around Cheju Island. The oxygen isotopic compositions of oyster and echinoid are well clustered, and they do not show any trend with increasing water temperature. Therefore, this could reflect that the organisms have not secreted their shells in oxygen isotopic equilibrium with ambient seawater due to vital effect. Thus, the oxygen isotopic composition of barnacle can potentially be utilized for paleotemperature estimate whereas those of other organisms in this study may not be useful.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.3
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• pp.112-123
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• 1998

The objectives of this study are to investigate the trace elemental and stable isotopic compositions of aragonitic mollusk shells, such as Gomphina veneriformis melanaegis, Mytilidae and Umbonium coastatum, from the eastern coast of Korean peninsula and Cheju Island, and to compare their variations with latitude, that is, the temperature of the ambient seawater at which the skeletons grew. The Mg compositions of Gomphina veneriformis melanaegis tend to decrease with increasing water temperature, whereas those of Mytilidae and Umbonium coastatum do not show any trend. Sr compositions of Mytilidae tend to increase with increasing water temperature, whereas those of Gomphina veneriformis melanaegis decrease. Fe compositions of Umbonium coastatum tend to decrease with increasing water temperature, whereas those of Gomphina veneriformis melanaegis increase. Fe compositions of Mytilidae do not show any trend with water-temperature variations. Ba compositions of all the skeletons do not show any trend with water-temperature variations. Cd compositions of Mytilidae and Umbonium coastatum do not show any trend with increasing water temperature, whereas those of Gomphina veneriformis melanaegis increase. Cu compositions of Gomphina veneriformis melanaegis increase with increasing water temperature, whereas Mytilidae and Umbonium coastatum do not show any trend. Pb compositions of Umbonium coastatum do not show any tend with increasing water temperature, but those of other skeletons increase. Zn compositions of Mytilidae tend to decrease with increasing water temperature, whereas those of Gomphina veneriformis melanaegis increase. Zn compositions of Umbonium coastatum do not show any trend with increasing water temperature. Estimated water temperatures from oxygen isotopic data of all the skeletons are higher than the range of water temperature of the shallow seawater of the East Sea and around Cheju Island. The oxygen isotopic compositions of all the skeletons are well clustered, but they do not show any trend with latitude. Therefore, this could reflect that the organisms may not have secreted their shells in oxygen isotopic equilibrium with ambient seawater due to vital effect. Thus, isotopic compositions of all the organisms in this study may not be suitable for paleotemperature estimate.

• Ocean and Polar Research
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• v.37 no.1
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• pp.49-59
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• 2015

Spatial variation in the reproductive effort of Manila clam Ruditapes philippinarum is often closely associated with variation in the seawater temperature and food availability, which determines gonad maturity and the quantity of gamates produced during spawning. Previous studies also have reported that severe infection by the protozoan parasite Perkinsus olseni exerts a negative impact on clam reproduction, retarding gonad maturation or decreasing the reproductive effort. In the present study, we investigated impacts of P. olseni infection on the reproductive condition of Manila clam during a spawning season. Histology revealed that 54% of female clams in Wando off the south coast were in spawning, while only 10% of the female from Gomso and 0% of the female from Seonjaedo in Gyeonggi bay off the west coast were engaged in spawning at the end of May in 2004. Ray's fluid thioglycollate media (RFTM) assay was applied to assess P. olseni infection and indicated that the infection intensity in Wando ($3,608,000{\pm}258,000cells/g$ wet tissue) was significantly higher than the levels in Gomso ($1,305,000{\pm}106,000cells/g$ wet tissue) and Seonjaedo ($1,083,000{\pm}137,000cells/g$ wet tissue, p < 0.001). The size of the ripe female follicle determined from histology was significantly smaller in Wando ($0.032mm^2$) compared to the sizes in Gomso ($0.059mm^2$) and Seonjaedo ($0.052mm^2$, p < 0.05). Accordingly, the number of ripe eggs in the follicle was significantly fewer among clams in Wando (14) compared to the numbers determined in Gomso (23) and Seonjaedo (22). The absolute quantity of egg in ripe clams from Wando (31.01 mg) was also significantly smaller than Seonjaedo (61.79 mg) and Gomso (133.3 mg). Quantity of total protein, carbohydrate, and lipid in the tissue in the Wando samples was significantly smaller than the quantities determined in Gomso and Seonjaedo (p < 0.001). The observed poor reproductive condition and proximate tissue composition of the females in Wando were, in part, explained by the extremely high level of the parasites, sapping the ability to store energy in the host tissues, which is used in tissue growth and the egg production.

• 한국해양학회지
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• v.30 no.4
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• pp.320-331
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• 1995

The closely spaced cores were analyzed to find detailed reconstruction of paleoenvironments and sealable changes along the Delaware Bay coast. Three areas, Kitts Hummock Beach mars, the St. Jones River marsh, and Bowers marsh near the St. Jones River's mouth, were chosen because these areas are compose of their own geomorphic characteristics and sea-level history. since significance of the stratigraphic correlations was to determine sedimentary fancies and paleoenvironments, multidisciplinary methods such as lithological description, grain-size analysis, organic/inorganic content, water content, mineral composition, botanical analysis, micropaleontological analysis, and /SUP 14/C datings were performed. Five major divisions of marsh environments were recognized in the stratigraphic sections: freshwater marsh, initialfreshwater marsh, slightly brackish marsh, brackish marsh, and salt marsh. Most of the lower part in the stratigraphic sections show freshwater marsh. On the top of this, either brackish marsh or tidal flat/tidal stream was recorded. The pro-Holocene sediments consist of sand, mud, and sandy mud, The pre-Holocene configuration played an important role for developing the Holocene Paleoenvironmental changes. The irregular configuration of the pre-Holocene sediments consist of sand, mud, and sandy mud. The pre-Holocene configuration played an important role for developing the Holocene Paleoenvironmental changes. The irregular configuration of the pre-Holocene surface within short distances permitted the concurrent development of variable environments such as freshwater marsh, brackish marsh or salt marsh at similar elevations. The freshwater marsh in this case was formed in the areas of isolation, so saline-water cannot encroach upon these areas. This complex development of paleoenvironments leads to a difficulty in stratigraphic correlation and interpretation of local relative sea-level changes. The deposition of subsurface sediments was affected by sediment supply, compaction, fluvial activity, biological competition, local tectonics and isostacy, climate and local relative sea-level changes. It was interpreted that the positions in the changes from freshwater environments to brackish environments or ice versa are the turning points of transgressions and regressions. Therefore, multiple transgressions and regressions were identified in the stratigraphic sections of the study area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.2
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• pp.76-90
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• 2018

To determine the distribution of mercury (Hg) in the coastal surface sediments around the Korean peninsula, the baseline concentration of Hg was estimated, the extent of contamination was assessed, and the factors controlling the distribution were discussed. The concentrations of Hg in surface sediments were significantly high in Jinhae-Masan Bay in the South Sea, Ulsan-Onsan Bay and Yeongil Bay in the East Sea, but Hg in other sediments showed a similar distribution to Cs and relatively very low concentration between 0.21 and $39.5{\mu}g/kg$ ($13.6{\pm}7.80{\mu}g/kg$). Compared to the sediment quality guidelines in Korea, 8 % of the surface sediments (n=282) analyzed in this study exceeded the values of the threshold effects level (TEL), and six sediments collected around Onsan Port were higher than the value of the probable effects level (PEL). The contamination levels of Hg were assessed by the enrichment factors using the baseline concentration (2.06Cs+1.75) based on the residual analysis from the linear regression line for Cs, and further, factors controlling the distribution of Hg were discussed by the comparison with geochemical substances depending upon the Hg enrichment level. Hg concentrations were correlated well with Cs concentration in the range of less than 1.69 of EF implying grain size control, while in the range of 1.69 and 4.03 Hg concentrations were correlated well with Fe oxyhyroxide and organic carbon contents, which indicates Hg was enriched by superior sorption capability. On the meanwhile, samples with higher EFs (4.03 to 74.9) showed fairly positive correlations with other metals (Cu, Zn, Pb) rather than geochemical substances. For samples in Youngil Bay and Ulsan-Onsan Bay (n=30), Hg concentrations were correlated only with other metals rather than geochemical substances implying simultaneous supply of metal particles from metal refineries. But samples at Gosung, Sokcho and Uljin coast were correlated well with organic carbon even though they had high EFs. In addition, samples in Jinhae-Masan Bay with high contents of S were enriched by relatively high sulfide formation.

• Journal of Aquaculture
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• v.14 no.3
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• pp.181-195
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• 2001

To stabilize the lantern cage culture system of Patinopecten yessoensis(Jay) in the eastern coast of Korean peninsula, optimum conditions such as time of transplantation, rearing density and depth, and time of harvest were identified. During the period from January 1991 to December 1998, the water temperature ranged from 4.7 to 21.4$^{\circ}C$ at 15-30 m depth and 4.9 to 25.7$^{\circ}C$ at the surface; these thermal ranges were within the optimal ranges (5-23$^{\circ}C$) prevailing at 15-30 m depth at surface water. Annual thermal changes indicated that the prevailing temperature during the years 1993 and 1996 was near optimum, but higher during the years 1994, 1997 and 1998, when mass mortality and growth retardation occurred. Salinity (32.0- 34.4$\textperthousand$) and dissolved oxygen (4.14 -8.11 $\mu\textrm{g}$/l) at 15 m depth were well within the optimum ranges. The chlorophyll concentrations (0.06 - 2.73$\mu\textrm{g}$/l) indicated that the study area was oligotrophic, although mass mortality did occur, when chlorophyll concentrations were high, especially in summer. Hence water temperatures and chlorophyll concentration are major factors related to survival and growth of the scallop. In terms of the shell height maximum growth occurred during spring (March-May; 8 - l3$^{\circ}C$) and fall (October-December; 11-l7$^{\circ}C$) in the lantern cage culture. Slow growth was recorded during late winter January-february; less than 7$^{\circ}C$) and mid-summer (August- September; more than 18$^{\circ}C$). Daily growth of shell height and total weight were 0.02∼0.24 mm and -0.07∼0.90 g at the rearing density of 12 individuals per net. Optimal .earing density in the lantern cage (ø50${\times}$20 cm) was 10∼15 individuals with the shell height of 5∼6 cm. The fastest growth rates were observed at 15∼20 m depth; however, it is recommended that 20∼30 m would be optimal. The scallops require 22 months to attain the commercial size of 10 cm shell height and 140 g total weigh, and are best harvested and sold during March-April.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.188-202
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• 1997

The seasonal variability of the sea surface winds over the last Sea of Korea (Japan Sea) is investigated by means of empirical orthogonal function (EOF) analysis. The combined representation of fields of three climatic variables by empirical orthogonal functions is discussed. The eigenvectors are derived from daily sea level pressure, wind speed and 10-day mean sea surface temperature (SST) during 15 years $(1978\~1992)$. The spatial patterns of the mean pressure are characterized by the high pressure in the western part and the low pressure in the eastern part. The spatial distribution of the standard deviation (SD) of pressure are characterized by max SD of 6.6 mb near the Vladivostok, and minima along the coast of the Japan. In Vladivostok, the maxima of SD of SST and south-north wind (WV) were also occurred. The representation of fields of individual meteorological variables by EOF shows that the first mode of the west-east wind (WU) explain over $47.3\%$ of the variance and the second mode of WU represents $30\%$. Especially, the first mode of the WV explain $70.9\%$ of the variance and their time series coefficients show 1-cpy, 0.5-cpy frequency spectrum. The spatial distribution of the first mode eigenvectors of SST are characterized by maximum near Vladivostok. The combined representation of fields of several variables (pressure, wind, SST) reveals that the first mode magnitudes of the variance of the combined eigenvectors (WU-PR) are increased. By means of this result, the 1-year peak and the 6-months peak are remarkable. In the three combined patterns (wind, pressure, SST), the second mode of the eigenvector (wind) is affected by the SST. Their time coefficients of the first mode show noticeable 1-year peak. The spectral analysis of the second mode shows broad seasonal signal with the period of 4-months and a significant peak of variability at 3-month period.

• Journal of the Mineralogical Society of Korea
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• v.31 no.1
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• pp.1-12
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• 2018

A gravity core (RS14-C2) was collected at site RS14-C2 in the continental slope to the east of Pennell-Isellin Bank of the Ross Sea (Antarctica) during PNRA XXIX (Rosslope II Project) Expedition. In order to trace the sediment source, magnetic susceptibility (MS), sand fraction, and clay mineral compositions were analyzed, and AMS $^{14}C$ ages were dated. Core sediments consist mostly of hemipelagic sandy clay or silty clay including ice-rafted debris (IRD). AMS $^{14}C$ age of core-top indicates the modern and Holocene sediments. Based on AMS $^{14}C$ dating, sediment color, MS and sand fraction, core sediments are divided into interglacial and glacial intervals. The interglacial brown sediments are characterized by low MS and sand fraction, whereas the glacial gray sediments are characterized by high MS and sand fraction. Among clay mineral compositions of core sediments, illite is highest (61.8~76.7%), and chlorite (15.7~21.3%), kaolinite (3.6~15.4%), and smectite (0.9~5.1%) are in decreasing order, and these compositions are also divided into the interglacial and glacial/deglacial intervals. During the glacial period, the high content of illite and chlorite indicate sediment supply from the bedrocks of Transantarctic Mountains under the Ross Ice Sheet. In contrast, because of decreasing supply of illite and chlorite by the glacial retreat, smectite and kaolinite contents increased relatively during the interglacial period. During the interglacial period, smectite may be transported additionally by the northeastward flowing surface current from the coast of Victoria Land in the western Ross Sea. Kaolinite may be also supplied to the continental slope by the Antarctic Slope Current from the kaolin-rich metasedimentary rock outcropped on the Edward VII Peninsula.

• Korean Journal of Remote Sensing
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• v.30 no.1
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• pp.83-107
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• 2014

This study presents spatial characteristics of cloud using satellite image in the extreme heavy snowfall of the Yeongdong region. 3 extreme heavy snowfall events in the Yeongdong region during the recent 12 years (2001 ~ 2012) are selected for which the fresh snow cover exceed 50 cm/day. Spatial characteristics (minimum brightness temperature; Tmin, cloud size, center of cloud-cell) of cloud are analyzed by tracking main cloud-cell related with these events. These characteristics are compared with radar precipitation in the Yeongdong region to investigate relationship between cloud and precipitation. The results are summarized as follows, selected extreme heavy snowfall events are associated with the isolated, well-developed, and small-scale convective cloud which is developing over the Yeongdong region or moving from over East Korea Bay to the Yeongdong region. During the period of main precipitation, cloud-cell Tmin is low ($-40{\sim}-50^{\circ}C$) and cloud area is small (17,000 ~ 40,000 $km^2$). Precipitation area (${\geq}$ 0.5 mm/hr) from radar also shows small and isolated shape (4,000 ~ 8,000 $km^2$). The locations of the cloud and precipitation are similar, but in there centers are located closely to the coast of the Yeongdong region. In all events the extreme heavy snowfall occur in the period a developed cloud-cell was moving into the coastal waters of the Yeongdong. However, it was found that developing stage of cloud and precipitation are not well matched each other in one of 3 events. Water vapor image shows that cloud-cell is developed on the northern edge of the dry(dark) region. Therefore, at the result analyzed from cloud and precipitation, selected extreme heavy snowfall events are associated with small-scale secondary cyclone or vortex, not explosive polar low. Detection and tracking small-scale cloud-cell in the real-time forecasting of the Yeongdong extreme heavy snowfall is important.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.2
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• pp.97-103
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• 2004

This paper presents a general overview of the Korean stick-held dip net fishery for Pacific saury operated in the North Pacific Ocean since 1985. Annual catches, annual centroids distribution of fishing ground, and optimum fishing temperatures were compared between the periods before and after the new Korea-Japan bilateral fishery arrangement established in 1998. Fishing usually began in May and ended by December, during which major catches were taken in the months September~November before the bilateral fishery arrangement between Korea and Japan, whereas in August~October after the arrangement. It was observed that after the arrangement the centroids of fishing ground was shifted from the usual fishing area off the east coast of Japan to the east of South Kuril Islands, 45$^{\circ}$N and 151$^{\circ}$E. Optimum fishing temperatures appeared to be different by month ; 12.5~14.4$^{\circ}C$ in May, 12.0~14.2$^{\circ}C$ in June, 11.4~13.9$^{\circ}C$ in July, 11.4~15.9$^{\circ}C$ in August, 12.9~16.9$^{\circ}C$ in September, 12.7~17.3$^{\circ}C$ in October, 13.1~17.6$^{\circ}C$ in November, and 15.0~19.1$^{\circ}C$ in December. A total of 13 species were caught during scientific observation periods but the target species, Pacific saury, accounted for about 99.9% of the total catch. Although there was no difference in fishing days between those vessels equipped with the sonar and those without sonar, number of set, total catch, and CPUE of those with sonar were higher than those without sonar by 13%, 26%, and 12%, respectively.