• Title/Summary/Keyword: coastal waters

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Relationship between Temperature Distributions and Outbreaks of Harmful Algal Blooms in Korean Waters

  • Han, In-Seong;Jang, Lee-Hyun;Sub, Young-Sang;Seong, Ki-Tack
    • Fisheries and Aquatic Sciences
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    • v.11 no.1
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    • pp.50-60
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    • 2008
  • Harmful algal blooms (HABs) of Cochlodinium polykrikoides frequently occur around the South Sea of Korea, causing. economic losses in coastal breeding grounds. HAB outbreak scale usually changes each year depending on physical, biological and environmental conditions. Relatively large-scale HABs occurred in 1995, 1997, 1999, 2001, 2002 and 2003 with respect to spatial scale, duration and maximum density. Considering HAB scale and temperature distributions around the South Sea, we found that low coastal temperatures in August correspond to enormous HAB outbreaks. Cold waters created by coastal upwellings around the southeastern coast of Korea also corresponded to these outbreaks. Serial oceanographic investigations in August in the South Sea revealed that sea surface temperature anomalies had distinctively negative values when large-scale HAB outbreaks appeared. With regard to temperature differences between the surface and the 30-m layer, there was a tendency for large-scale outbreaks when temperature gradients around the seasonal thermocline weakened.

Gut Composition of Postlarval and Juvenile Anchovy Engraulis japonicus in the Coastal Waters of Yeosu, Korea (여수 연안에 출현하는 멸치(Engraulis japonicus) 후기자어 및 치어의 소화관 내용물 조성)

  • Yoo, Joon-Taek;Jeong, Jae Mook
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.49 no.5
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    • pp.642-647
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    • 2016
  • Postlarval and juvenile anchovies Engraulis japonicus were collected using a gape net with wings in the coastal waters of Yeosu in July and August 2015, and their gut contents were analyzed. The size range of the postlarvae was 11.0-24.2 mm (notochord length) and that of the juveniles was 25.1-37.4 mm (standard length). Guts were empty in 64.5% of postlarvae and in 51.7% of juveniles. The dominant prey organisms in the guts of both postlarvae and juveniles were copepoda. Calanoida were important prey organisms for postlarvae and were dominated by nauplii of Paracalanus sp. and Calanus sp. as well as unidentified copepod naupill. Calanoida were also important in the diets of juveniles, whose gut contents were dominated by Paracalanus sp. and Cirripedia. Gut compositions were significantly different (P<0.05) among three body size levels in postlarvae and juveniles. As the body size of the postlarvae and juveniles increased, Calanoida constituted a larger proportion of the gut contents, while the proportion of copepod nauplii decreased.

MEASUREMENT OF SPECTRAL-ANGULAR RADIANCES OF COASTAL WATERS IN THE KOREAN SOUTH SEA

  • Ahn, Yu-Hwan;Shanmugam, Palanisamy;Ryu, Joo-Hyung;Moon, Jeong-Eon
    • Proceedings of the KSRS Conference
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    • 2007.10a
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    • pp.156-158
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    • 2007
  • The radiance observed from the ocean depends on the illumination and viewing geometry along with the water properties, and this variation is called the bidirectional effect which is important to be considered in ocean color remote sensing. In the present study, as a preliminary step, the spectral-angular radiances in coastal water were investigated with experiments for a range of viewing geometric conditions $(0-70^{\circ})$. Over a phytoplankton-dominated water surface the upward radiance for visible and near-infrared wavelengths (example, SeaWiFS and GOCI) increased at nadir and decreased toward the near-horizon, becoming dependent of viewing angles (with higher radiance at nadir view angle and lower radiance at near-horizon viewing angle). This variations were better expressed by the Q-factor, which relates upwelling radiance to the upwelling irradiance (i.e., $Q=E_u/L_u$, also dependent on Sun's position). The Q-factor for this case was more non-uniform with the considered wavelengths and was dependent on viewing geometric conditions. These experimental results confirm the previous similar findings in other coastal waters.

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Heavy Metals In The Korean Coastal Waters During Summer Of 1977 (여름철 한국 연안해수중의 중금속 함량)

  • Lee, Kwang Woo;Kwak, Hi-Sang;Lee, Soo Hyung;Lee, Dong Soo
    • 한국해양학회지
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    • v.14 no.1
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    • pp.1-5
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    • 1979
  • In order to investigate water quality of coastal waters, samples were collected from the six coastal areas of Korean peninsula during summer of 1977, and analyzed for Cd, Cu, Fe, Pb and Zn by atomic absorption spectrophotometry. The results showed no significant heavy metal pollution in most parts of the studied areas in comparison with results of other countries in literature. However, strong possibility of some specific heavy metal pollution is shown in the specific areas, such as Cu and Pb in the Sea off Cunsan, Pb in Kwangyang Bay and Cd and Pb in Ulsan Bay.

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Web MGIS with SVG of Kosrae Costal Waters, Micronesia (SVG를 이용한 마이크로네시아 코스레 주변해역 Web MGIS 구축)

  • Park, Sang-Woo;Kim, Jung-Hyun;Lee, Moon-Ock;Kim, Hyeon-Ju;Kim, Jongkyu
    • Journal of Fisheries and Marine Sciences Education
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    • v.26 no.3
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    • pp.485-491
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    • 2014
  • The study of Web MGIS(Marine Geographic Information System) based on the SVG(Scalable Vector Graphics) is mainly performed on effective methodologies which transform real world data to computing world data. Web GUI system has its own target on reliable data service by acquisition of geometric information using HYCOM(HYbrid Coordinate Ocean Model), accurate measurement and graphical visualization. This type of raw data visualization can be built without software tools, yet is incredibly useful for interpreting and communicating data. Even simple visualizations can aid in the interpretation of complex hydrodynamic relationships that are frequently encountered in the marine environment. The Web MGIS provides an easy way for hydrodynamic geoscientists to construct complex visualizations that can be viewed with free software. This study proposes a Web GUI MGIS using FVCOM(Finite Volume Coastal Ocean Model). Finally, we design a Marine Web GUI system of Kosrae Coastal Waters integrating above data models. It must adds more ecological information and the various service item for approach more easily in order to user.

Comparison of the Spawning Characteristics of the Yellow Striped Flounder Pseudopleuronectes herzensteini in the Coastal Waters off Gangwon and Gyeongbuk, Korea (동해안에 서식하는 참가자미(Pseudopleuronectes herzensteini)의 해역별 산란특성 비교)

  • Kim, So Ra;Lee, Soo Jeong;Yang, Jae Hyeong
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.54 no.3
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    • pp.318-328
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    • 2021
  • We investigated the maturity and spawning of the brown sole Pseudopleuronectes herzensteini, in the coastal waters of the East Sea off Gangwon and Gyeongbuk, South Korea, using samples collected by gill net and longline fishery from January 2018 to December 2019. We analyzed oocyte development, monthly maturity stage, gonadosomatic index (GSI) and total length at maturity. Histological analysis of ovarian development in P. herzensteini revealed that the development was group-synchronous. The spawning peak in Gangwon and Gyeongbuk occurred from April to May and from February to March, respectively. Thus, the spawning season in Gangwon was 1-2 months later than that in Gyeongbuk. The length at 50% maturity for females was estimated as 24.2 cm and 19.0 cm in Gangwon and Gyeongbuk, respectively. Similarly, the length at 50% maturity for males was estimated as 19.8 cm and 16.5 cm in Gangwon and Gyeongbuk, respectively.