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Physical Characteristics and Classification of the Ulleung Warm Eddy in the East Sea (Japan Sea) (동해 울릉 난수성 소용돌이의 물리적 특성 및 분류)

SHIN, HONG-RYEOL;KIM, INGWON;KIM, DAEHYUK;KIM, CHEOL-HO;KANG, BOONSOON;LEE, EUNIL
- The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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- v.24 no.2
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- pp.298-317
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- 2019
The physical characteristics of the Ulleung Warm Eddy (UWE) and its relationship with the East Korea Warm Current (EKWC) were analyzed using the CMEMS (Copernicus Marine Environment Monitoring Service) satellite altimetry data and the CTD data of the National Institute of Fisheries Science (NIFS) near the Ulleung Basin from 1993 to 2017. The distribution of the UWEs coupled with EKWC accounts for 81% of the total number of the UWEs. Only 7% of the total eddies are completely separated from the EKWC. The UWE has the characteristics of high temperature and high salinity water inside of it when it is formed from the EKWC. However, when the UWE is wintering, its internal structure changes greatly. In the winter, surface homogeneous layer of $10^{\circ}C$ and 34.2 psu inside of the UWE is produced by vertical convection from sea-surface cooling, and deepened to a maximum depth of approximately 250 m in early spring. In summer, the UWE changes into a structure with a stratified structure in the upper layer within a depth of 100 m and a homogeneous layer made in winter in the lower layer. 62 UWEs were produced for 25 years from 1993 to 2017. on average, 2.5 UWEs were formed annually, and the average life span was 259 days (approximately 8.6 months). The average size of the UWEs is 98 km in the east-west direction and 109 km in the north-south direction. The average size of UWE using satellite altimetric data is estimated to be 1~25 km smaller than that using water temperature cross-sectional data.
https://doi.org/10.7850/jkso.2019.24.2.298 인용 PDF KSCI HTML

The Impact on Fish Assemblage by the River Connectivity Fragmentation: Case Study of the Danjang Stream, South Korea (하천 연속성 단절이 어류상에 미치는 영향: 밀양 단장천을 중심으로)

Seung-Been Heo;Kang-Hui Kim;Donghyun Hong;Hyeon-Sik Lee;Gu-Yeon Kim;Gea-Jae Joo;Hyunbin Jo
- Korean Journal of Ecology and Environment
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- v.55 no.3
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- pp.231-243
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- 2022
Anthropogenic disturbances on freshwater ecosystem are known to degrade biodiversity, especially on fish assemblage. In this study, we have conducted fish surveys to identify impact of a bridge construction on fish assemblages. A total of eight study sites were surveyed in the Danjang and the Dong Stream in southern part of South Korea from June to November in 2021. The fish samplings were carried out five times, using cast-nets(10×10 mm mesh size), scoop-nets(4×4 mm, 5×5 mm mesh size), set-nets (10×10 mm mesh size), and fish traps (3×3 mm mesh size), along with the Stream/River Ecosystem Survey and Health Assessment by the Ministry of Environment of Korea and basic water quality measurement. Also, we applied the species diversity index and length-weight relationship regressions on certain species to identify interspecific growth rate differences in accordance with study sites. As a result, a total of 782 individuals, 23 species and 10 families were collected. The dominant species was Zacco Koreanus and relative abundance was 50.89%. When applying the length-weight relationship regressions on certain species, the 'b' value for Z. Koreanus was lower at the downstream points than at the upstream points of the construction site. In addition, when comparing to the results of the past survey, relative density of demersal fish at the upstream and downstream points decreased from 26% to 1.4%, and from 18% to 6.3%, respectively. In conclusion, it is considered that bridge construction negatively affects the habitat of fishes, especially on demersal fishes. Therefore, appropriate conservation efforts such as installation of silt protector and sand sedimentation pond are needed to alleviate the disturbance in habitat such as occurrence of turbidity and destruction of micro-habitats.
https://doi.org/10.11614/KSL.2022.55.3.231 인용 PDF KSCI