• Article

    Numerical Simulation of Ocean - Ice Shelf Interaction: Water Mass Circulation in the Terra Nova Bay, Antarctica

    해양-빙붕 상호작용을 고려한 남극 테라노바 만에서 수괴 형성과 순환의 수치 시뮬레이션

    Taekyun Kim, Emilia Kyung Jin, Ji Sung Na, Choon Ki Lee, Won Sang Lee, Jae-Hong Moon

    김태균, 진경, 나지성, 이춘기, 이원상, 문재홍

    The interaction between ocean and ice shelf is a critical physical process in relation to water mass transformations and ice shelf melting/freezing … + READ MORE
    The interaction between ocean and ice shelf is a critical physical process in relation to water mass transformations and ice shelf melting/freezing at the ocean-ice interface. However, it remains challenging to thoroughly understand the process due to a lack of observational data with respect to ice shelf cavities. This is the first study to simulate the variability and circulation of water mass both overlying the continental shelf and underneath an ice shelf and an ice tongue in the Terra Nova Bay (TNB), East Antarctica. To explore the properties of water mass and circulation patterns in the TNB and the corresponding effects on sub ice shelf basal melting, we explicitly incorporate the dynamic-thermodynamic processes acting on the ice shelf in the Regional Ocean Modeling System. The simulated water mass formation and circulation in the TNB region agree well with previous studies. The model results show that the TNB circulation is dominated by the geostrophic currents driven by lateral density gradients induced by the releasing of brine or freshwater at the polynya of the TNB. Meanwhile, the circulation dynamics in the cavity under the Nansen Ice shelf (NIS) are different from those in the TNB. The gravity-driven bottom current induced by High Salinity Shelf Water (HSSW) formed at the TNB polynya flows towards the grounding line, and the buoyance-driven flow associated with glacial meltwater generated by the HSSW emerges from the cavity along the ice base. Both current systems compose the thermohaline overturning circulation in the NIS cavity. This study estimates the NIS basal melting rate to be 0.98 m/a, which is comparable to the previously observed melt rate. However, the melting rate shows a significant variation in space and time. - COLLAPSE
    30 December 2022
  • Article

    The Effect of Antenna Pattern Measurement According to Radio Wave Environment on Data Quality of HF Ocean Radar

    전파환경에 따른 안테나패턴 측정(APM) 결과가 고주파 해양레이더의 자료 품질에 미치는 영향

    Jae Yeob Kim, Dawoon Jung, Seok Lee, Kyu-Min Song

    김재엽, 정다운, 이석, 송규민

    High-frequency (HF) radar measures sea surface currents from the radio waves transmitted and received by antenna on land. Since the data quality … + READ MORE
    High-frequency (HF) radar measures sea surface currents from the radio waves transmitted and received by antenna on land. Since the data quality of HF radar measurements sensitively depend on the radio wave environment around antenna, Antenna Pattern Measurements (APM) plays an important role in evaluating the accuracy of measured surface currents. In this study, APM was performed by selecting the times when the background noise level around antenna was high and low, and radial data were generated by applying the ideal pattern and measured pattern. The measured antenna pattern for each case was verified with the current velocity data collected by drifters. The radial velocity to which the ideal pattern was applied was not affected by the background noise level around antenna. However, the radial velocity obtained with APM in the period of high background noise was significantly lower in quality than the radial velocity in a low noise environment. It is recomended that APM be carried out in consideration of the radio wave environment around antenna, and that the applied result be compared and verified with the current velocity measurements by drifters. If it is difficult to re-measure APM, we suggest using radial velocity in generating total vector with the ideal pattern through comparative verification, rather than poorly measured patterns, for better data quality. - COLLAPSE
    30 December 2022
  • Article

    Chemical Characteristics and Deposition of Aerosols in the Cheju-Korea Straits

    제주-대한해협 해역에서 에어로졸의 화학적 특성과 침적

    Suk Hyun Kim, Hyunmi Lee, Deok-Soo Moon

    김석현, 이현미, 문덕수

    To understand the chemical composition of aerosols in the Cheju-Korea Straits and their contribution to the ocean by deposition, aerosol samples were … + READ MORE
    To understand the chemical composition of aerosols in the Cheju-Korea Straits and their contribution to the ocean by deposition, aerosol samples were collected on board R/V Eardo from November 1997 to May 1999. The average concentrations of Al, NO3-, non-sea-salt (nss)-SO42-, and NH4+ in aerosols were 2.19, 5.59, 6.16 and 2.08 μg m-3, respectively. The Al concentration in the high yellow dust period was about 100 times higher than that in the non-yellow dust period. The concentration ratio of NO3-/nss-SO42- ranged between 0.47 and 1.5, indicating that the aerosols in the Cheju-Korea Straits are under the effects of NOx and SOx emitted from China, Korea and Japan. The equivalent concentration ratio of [NH4+]/[nss-SO42- + NO3-] with the average of 0.58±0.29 indicates that nss-SO42- and NO3- are not neutralized by NH4+. A high activity concentration of 210Pb with 1.13–1.23 mBq m-3 was observed during the high yellow dust period, indicating that 210Pb is easily adsorbed in the yellow dust originating from the continent of Asia. The distribution of 7Be and NH4+ concentrations showed a strong negative linear correlation during the low yellow dust period, April 1998. The total mineral dust flux in the Cheju-Korea Straits was estimated to be 1.21×106 tons yr-1, accounting for about 12% of the annual sediment discharge via the Nakdong River. The combined annual deposition of NH4+ and NO3- was 0.103 mole N m-2 yr-1 was estimated to support 4% of the annual primary productivity in the East China Sea. - COLLAPSE
    30 December 2022
  • Article

    Effects of Seed Preservation Periods and Soil Composition on the Seed Germination and Seedling Growth of Halophyte Suaeda japonica

    염생식물 칠면초(Suaeda japonica)의 종자발아와 유묘생장에 종자 보관기간과 토양구성이 미치는 영향

    Yong Sung Kwak, Si Eun Kim, Ji Chul Oh, Seo Kyoung Park, Han Gil Choi

    곽용성, 김시은, 오지철, 박서경, 최한길

    Seed germination and seedling growth of a halophyte, Suaeda japonica were examined to measure the effects of seed preservation periods and various … + READ MORE
    Seed germination and seedling growth of a halophyte, Suaeda japonica were examined to measure the effects of seed preservation periods and various soil compositions in the mudflat of Saemangeum, Korea. Seed germination declined from 74.30% to 44.30% as the preservation period increased from 4 months to 12 months. After 14 days of seeding, seed germination was lowest in sandy soil (SS) at 8.67% and highest in earthworm cast+leaf mold (EC+LM) at 67.33%, showing 4~5 times higher than SS. The average lengths of seedlings were 12.20 mm in SS and 42.20 mm in EC+LM, respectively. These results suggest that seed germination and seedling growth enhanced in the soil that has more organic matter. In the experiment mixing Saemangeum soil (SMS), seed germination was from 4.00% in SMS to 88.00% in the soil of SMS+EC+LM after 14 days. Similar growth patterns were observed in the length of seedlings from 5.00 mm in SMS to 49.60 mm in SMS+EC+LM. The present results indicate that a population of Suaeda japonica could be established by stimulating seed germination and seedling growth by the addition of organic matters such as EC, LM, and EC+LM in the Saemangeum mud flat. - COLLAPSE
    30 December 2022
  • Article

    Effects of Ovarian Parasite Marteilioides chungmuensis on the Reproduction of the Pacific Oyster Crassostrea gigas Assessed by Histology and Enzyme-Linked Immunosorbent Assay (ELISA)
    Yanin Limpanont, Hyun-Sil Kang, Young-Ghan Cho, Jong-Seop Shin, Nobuhisa Kajino, Jeong-Hwa Kim, Hyun-Ki Hong, Kwang-Sik Choi
    The paramyxean parasite Marteilioides chungmuensis infects the cytoplasm of the eggs of Pacific oysters Crassostrea gigas, resulting in spawning failure of … + READ MORE
    The paramyxean parasite Marteilioides chungmuensis infects the cytoplasm of the eggs of Pacific oysters Crassostrea gigas, resulting in spawning failure of the infected females. Such infected eggs appear as bump-like nodules on the body in late fall when most of the uninfected females complete spawning. In this study, we estimated the quantity of the infected eggs using an enzyme-linked immunosorbent assay (ELISA), which is destroyed by M. chungmuensis parasitism. In December, the infected oysters collected from Tongyoung on the south coast exhibited numerous yellowish bump-like nodules as signs of infection. In histology, the infected oysters exhibited mature eggs in the follicle, which were heavily infiltrated by hemocytes. ELISA indicated that the infected egg mass accounted for 7.52±5.50 percent of the body weight, suggesting the ovarian parasite causes substantial reproductive loss. Histology also indicated that the infected oysters are in a poor nutritional condition, as the digestive gland atrophy (DGA) level is comparatively higher than the uninfected oyster. The total carbohydrate contents in the infected oysters (108.68±44.41 mg/g dry wt) were significantly lower than in uninfected oysters (269.76±50.97 mg/g dry wt), suggesting that M. chungmuensis parasitism also affected the energy storage capacity of the host during the resting stage. - COLLAPSE
    30 December 2022
  • Article

    Mollusk Species Associated with the Scleractinian Coral Alveopora japonica Eguchi, 1968 Forming a Coral Carpet in Northwestern Jeju Island
    Ronald G. Noseworthy, Hyun-Ki Hong, Se-Jong Ju, Hyun-Sung Yang, Kwang-Sik Choi
    The high latitude scleractinian coral Alveopora japonica Eguchi, 1965 occurs in high density in the shallow rocky subtidal in Jeju Island, forming … + READ MORE
    The high latitude scleractinian coral Alveopora japonica Eguchi, 1965 occurs in high density in the shallow rocky subtidal in Jeju Island, forming coral carpets. Despite its ecological role providing a unique habitat for other benthic organisms, the benthic fauna associated with the A. japonica coral carpet is poorly known. To identify fauna associated with the coral carpet, we explored three sites dominated by A. japonica and one control site on northwestern Jeju Island in May 2013. Using SCUBA, we collected A. japonica and the epibenthic mega-fauna associated with the colonies in 1×1 m2 and identified them to the species level. At a depth of 10 to 15 m, A. japonica colonies heavily covered the seafloor, forming a layer called a coral carpet, with a density of 94 (Keumneung-ri), 133 (Biyangdo), and 155 (Gwidok-ri) colonies/m2. Thirty-four molluscan species were identified from the four sites, including 20 bivalves and 14 gastropods. The coral carpets were enriched with sessile bivalves compared to the control site, as we identified twenty bivalve and eight gastropod species from the coral carpets. Most bivalve species associated with the coral carpets had tropical-subtropical affinities, while gastropods were mainly subtropical and subtropical-low boreal species. Leiosolenus lischkei M. Huber, 2010, in the family Mytilidae and Barbatia steamsi (Pilsbry, 1895), in the family Arcidae, were the two most abundant bivalve species in the coral carpet, L. lischkei being a borer, and B. stearnsi a nestler. The tropical to subtropical Pacific star shell Astralium haematragum (Menke, 1829)was the most abundant gastropod at the study sites. The bivalves and gastropods associated with the coral carpet were small-sized juveniles or sub-adults, suggesting that the coral carpet provides a micro-habitat for the bivalves and gastropods. - COLLAPSE
    30 December 2022
  • Article

    Research of International Comparison about Ranging the Marines Protected Areas (MPA)

    국가 해양보호구역 지정규모에 관한 국제비교 연구

    Duckhee Jang, Changyoul Lee, Eun-Young Cho

    장덕희, 이창열, 조은영

    The purpose of this research is to conduct an empirical analysis regarding Korea’s ‘Marine Protected Areas (MPA)’ from an international comparative perspective. … + READ MORE
    The purpose of this research is to conduct an empirical analysis regarding Korea’s ‘Marine Protected Areas (MPA)’ from an international comparative perspective. The authors would like to present the policy direction of marine protected areas based on the result of the research. The result of this study can be summarized in the following manner: First, the total designated size of marine protected areas in Korea is very small compared to the sizes of other OECD nations. Second, while some nations have expanded the extent of marine protected areas in accordance with international agreements and criteria, Korea has not done so. Accordingly, we propose the designated dimensions of marine protected areas should be constantly expanded to keep pace with international trends. - COLLAPSE
    30 December 2022
  • Note

    Efficient Searching for Shipwreck Using an Integrated Geophysical Survey Techniques in the East Sea of Korea

    동해에서 지구 물리 이종방법간의 결합시스템을 활용한 침선 수색의 효용성 연구

    Lee-Sun Yoo, Nam Do Jang, Seom-Kyu Jung, Seunghun Lee, Cheolku Lee, Sunhyo Kim, Jin Hyung Cho

    유이선, 장남도, 정섬규, 이승훈, 이철구, 김선효, 조진형

    When the 60-ton-class patrol boat ‘72’ of the Korea Coast Guard (KCG) was on duty and she accidentally collided with another patrol … + READ MORE
    When the 60-ton-class patrol boat ‘72’ of the Korea Coast Guard (KCG) was on duty and she accidentally collided with another patrol boat (‘207’, 200-ton-class) and sank. A month-long search found a small amount of lost items, but neither the crew nor the ship was found. For the first time in 39 years since the accident, the Korea Institute of Ocean Science and Technology (KIOST) searched the boat 72 using the latest integrated geophysical techniques. A number of sonar images presumed to be of a sunken ship was acquired using a combined system of side scan sonar and marine magnetometer, operated at an altitude of approximately 30 m from the seabed. At the same time, a strong magnetic anomaly (100 nT) was detected in one place, indicating the presence of an iron ship. A video survey using a remotely operated underwater vehicle (ROV) confirmed the presence of a shielding part of a personal firearm at the stern of the sunken vessel. Based on these comprehensive data, the sunken vessel discovered in this exploration was assumed to be ‘72’. This result is meaningful in terms of future ocean exploration and underwater archaeology, as the integrated system of various geophysical methods is an efficient means of identifying objects present in the water. - COLLAPSE
    30 December 2022
  • Note

    Growth Performance of Juvenile Red-spotted Grouper (Epinephelus akaara) ♀ × Giant Grouper (E. lanceolatus) ♂ Hybrid across Temperatures
    Min Joo Kang, Sung Jin Yoon, Choong Hwan Noh
    The present study measured the growth performance of juvenile hybrid of red-spotted grouper ♀ × giant grouper ♂ (RGGG) across four water … + READ MORE
    The present study measured the growth performance of juvenile hybrid of red-spotted grouper ♀ × giant grouper ♂ (RGGG) across four water temperatures (19, 23, 27, and 31°C) and compared it to those of maternal purebreds (red-spotted grouper ♀ × ♂, RG) for eight weeks. The specific growth rate (SGR) and weight gain (WG) of RGGG increased as temperature increased, with greater SGR and WG at higher temperatures (27 and 31°C) than RG. The condition factor of RGGG was higher than that of RG and there were no differences between temperature groups within breeding lines. Food consumption increased at higher temperatures for both RGGG and RG, and was the highest in the 31°C group. Similar to the SGR and WG, the food conversion rate (FCR) in RGGG decreased with increasing water temperature, with the significantly lowest value at 31°C; in RG, however, FCR progressively decreased in the 27°C group, then increased in the 31°C group. Furthermore, the FCR of the 31°C group of RGGG, which had the lowest value among the RGGG groups, was lower than that of the 27°C group of RG, which had the lowest RG value. In the analysis of nonlinear regression curves within the range of experimental temperature, the optimum temperature for SGR and FCR in RGGG was 31°C, unlike in RG. In conclusion, the growth performance of juvenile RGGG seems to have largely improved from the influence of paternal traits, hybrid with giant grouper, and it is presumed to be more profitable for commercial production in tropics/subtropics. - COLLAPSE
    30 December 2022