• Journal of fish pathology
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• v.24 no.3
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• pp.197-204
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• 2011

The edible ascidian Halocynthia roretzi is a commercially important fisheries resource in Korea. However, for the last several years, outbreaks of mass mortalities of the species have been occurring along the south and east coasts of Korea, where most ascidians are produced. Although it is known that tunic-softness syndrome is associated with these mortality events, the agent causing the syndrome has not yet been confirmed. To determine the agent causing tunic-softness syndrome, healthy and diseased ascidians were collected in March 2011 from Tongyeong, on the south coast of Korea, and were used for biological and pathological investigations. The results showed that diseased ascidians exhibited remarkably reduced body fluid, fatness index, and tunic index compared with healthy specimens. Interestingly, bi-flagellated protozoans were observed specifically in the tissue imprints and tunic cultures of diseased ascidians at an occurrence rate of 97.5%. Histological observation showed that the thickness of the tunics of diseased ascidians was reduced by half, and irregular structure and breakdown of the tunic fiber bundles were observed. In particular, flagellate-like cells were observed in the diseased ascidians. Our study clearly shows that bi-flagellated protists are present only in the softened ascidians, suggesting that the flagellates are partly or entirely associated with soft-tunic syndrome. Accordingly, further investigations to verify the effects of the flagellates found in the present study on soft-tunic syndrome should be conducted.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.179-187
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• 2018

In order to understand the flow of currents around Aphae Island and the surrounding Archipelago, the numerical model experiments on tidal currents and tide-induced residual currents were carried out. Dominant semidiurnal tidal currents have a reversing form and flow along the narrow channels of the archipelago. During periods of flood, currents flow from the west of Hwawon Peninsula to the archipelago to the northwest together with the currents flowing from the channels at Palgeum Island to Amtae Island and Amtae Island to Jeung Island. Ebb currents flow from the northwest archipelago to the channel of Amtae Island and Jeung Island as well as Amtae Island to Palgeum Island, further flowing south between Palgeum Island and Hwawon Peninsula. Flood currents are separated from east and west at the southern coast of Aphae Island, but flow south from both the west and east of Aphae Island to the channel found between Palgeum Island and Hwawon Peninsula at ebb. Flow speed is high between Amtae Island and Aphae Island where the flows meet and join. Lee wakes or topographical eddies are formed around the islands due to the high speed of the currents flowing along the narrow channel in the archipelago, manifesting as a tide-induced residual current. A weak cyclonic wake and anti-cyclonic eddy both exist at the west and northwestern coast of Aphae Island individually. The speed of the tide-induced residual current become slow on account of the wide littoral zone at exists around Aphae Island.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.4
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• pp.217-224
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• 2010

This study was carried out to quantify potential effects of the surrounding ocean on the observed air temperature at coastal weather stations in the Korean Peninsula. Daily maximum and minimum temperature data for 2001-2009 were collected from 66 Korea Meteorological Administration (KMA) stations and the monthly averages were calculated for further analyses. Monthly data from 27 inland sites were used to generate a gridded temperature surface for the whole Peninsula based on an inverse distance weighting and the local temperature at the remaining 39 sites were estimated by recent techniques in geospatial climatology which are widely used in correction of small - scale climate controls like cold air drainage, urban heat island, topography as well as elevation. Deviations from the observed temperature were regarded as the 'apparent' sea effect and showed a quasi-logarithmic relationship with the distance of each site from the nearest coastline. Potential effects of the sea on daily temperature might exceed $6.0^{\circ}C$ cooling in summer and $6.5^{\circ}C$ warming in winter according to this relationship. We classified 25 sites within the 10 km distance from the nearest coastline into 'coastal sites' and the remaining 15 'fringe sites'. When the average deviations of the fringe sites ($0.5^{\circ}C$ for daily maximum and $1.0^{\circ}C$ for daily minimum temperature) were used as the 'noise' and subtracted from the 'apparent' sea effects of the coastal sites, maximum cooling effects of the sea were identified as $1.5^{\circ}C$ on the west coast and $3.0^{\circ}C$ on the east and the south coast in summer months. The warming effects of the sea in winter ranged from $1.0^{\circ}C$ on the west and $3.5^{\circ}C$ on the south and east coasts.

• Ocean and Polar Research
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• v.24 no.1
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• pp.115-121
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• 2002

Yubu Island is located within the estuary of the Geum River, South Chungcheong Province $(35^{\circ}59'N,\;126^{\circ}36'E)$, Korea. The island is surrounded by a broad and sandy mudflat, which is typical in the west coast of Korea, and is located 4km off from Gunsan City. Less than 100 humans live on the island, occupying 30 houses. After we discovered that this island was a very important waterbird habitat especially for the East Asian subspecies of the Eurasian oystercatcher, Haematopus ostralegus osculans. Waterbirds were monitored once every month from August 1999 to July 2000. The highest number of oystercatchers counted was 3,200 in December 1999, and the birds seemed to remain in the area continuously from September to next February. About 200 breeding and non-breeding birds remained during the breeding season. In August, early migrants returned to the island, with the number reaching 1,060 individuals. This island is also very important for other waterbirds. Endangered or significant species occurring at this site, and their maximum counts were: chinese egret Egretta eulophotes (5), black-faced spoonbill Platalea minor (17), brant Branta bernicla (1), common shelduck Tadorna tadorna (8,000), hooded crane Grus monacha (2), spoon-billed sandpiper Ewynorhynchus pygmeus (7), dunlin Calidris alpina (6,500), great knot Calidris tenuirostris (24,000), far eastern curlew Numenius madagascariensis (2,500), spotted greenshank Tringa guttifer (4) and Saunders's gull Larus saundersi (1,200). During the 12 month survey period, we observed 52 waterbird species and the total of the maximum counts for the separate species was 73,308, implying that perhaps 150,000 birds could be using the immediate area, if a turnover rate of 2 was assumed.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.553-556
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• 2004

Spatial and temporal aspects of toxic dinoflagellate Cochlodinium.p blooms and consequences of physical features in complex coastal ecosystems, off the southern Korean coast, have been investigated using data obtained from SeaWiFS and AVHRR as well as in-situ observations. Hydrographic parameters measured using CTD sensors were used to elucidate physical factors affecting the spatial distribution and abundance of Cochlodinium.p blooms. The results show spatial and temporal variations of chlorophyll-a (Chl-a) and sea surface temperature (SST) and reveal significant information about Cochlodinium.p blooms and process underlying their evolution. Satellitederived Chl-a estimates appear to be potential in explicating the evolution, movement and distribution of Cochlodinium.p blooms in the enclosed bays of the South Sea. The existence of thromohaline waters offshore provide favorable conditions for the rapid growth and subsequent southward initiation of Cochlodinium.p blooms that are influenced to flow on the offshore branch (OB) during September. It was observed that there was a significant variation in the sun-induced chlorophyll-a fluorescence signal in the remote sensing fluorescence spectra and its high-intensity was recognized during the period of exponential growth and physical transport. Satellite-derived Chl-a concentration during September 1999 ranged between $3­60mg/m^3$ inside the Jin-hae and adjacent Bays and $1-6mg/m^3$ in offshore waters, with varying Cochlodinium.p abundances 1500 to 26000 cells $ml^{-1}.$ The closely spaced CTD surveys and satellite-derived SST give a complete overview on the initiation of Cochlodinium.p blooms in hydrodynamically active regions of the offshore southern East Sea by the influence of Tsushima Warm Current (TWC).

• Korean Journal of Environment and Ecology
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• v.30 no.1
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• pp.104-109
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• 2016

In Korea, the government has invested the installation of artificial reefs (ARs) which deploying to enhance the restoration of marine environment and productivity on the coastal area at the part of 222,627ha, from 1971 to 2014 for 44 years. The number of ARs are gradually increasing, while their comparison and corelation analysis were not much studied. Therefore, this study is to analyse temporal variation of ARs which composed of concrete named the Horn triangle reefs were deployed at Pohang, Jangkil-ri, a depth of 5 to 7m, in 2003, was monitored 4 times from 2009 to 2011. In results, the biodiversity investigated that the dominant species was Mollusca Omphalius pfeifferi except in 2009. The different species mainly depend on spatial-temporal variation. In this type of study can be used to the R&D, management and government policy of ARs as well improving marine environment.

• 한국해양학회지
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• v.21 no.3
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• pp.136-145
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• 1986

Biotope analysis(UPGM) of the data on the total benthic foraminferal assemblage (Kim and Han, 1982) collected from the southeastern sea off the Korean Peninsula shows that foraminiferal assemblages are related to the water masses prevailing in the study area. South Proper facies is governed by the Tsushima Warm Current, and Southern Deep facies is influenced by the cold water mass moved down along the bottom. Northern Nearshore facies is governed by the North Korea Cold Current, and North Proper facies is affected by the North Korea Cold Current and Japan Sea Proper Water. It is also evident that the upper part of the study area is under the influence of the North Korea Cold Current rather than the East Korea Warm Current which flows northward along/or off the right side of the study area. Planktonic foraminiferal occurrence also supports this biotope analysis.

• Economic and Environmental Geology
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• v.18 no.2
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• pp.167-175
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• 1985

Geothermal heat flow distribution of Korea is investigated in the light of geophysical data, seismicity, tectonics and gravity as well as heat flow measurements and surface temperature of hot springs. The average heat flow in Korea is found to be $1.65{\mu}cal/cm^2{\cdot}sec$ that is greater than the world's average ($1.5{\mu}cal/cm^2{\cdot}sec$). The high heat flow is located at the regions of high seismicity in Korea. They are found to be Bugok of south central, and Haeundae, Pohang and Dongnae of the southest coast in the Peninsula. The anomalously high heat flow, equal to or greater than $1.93{\mu}cal/cm^2sec$ is found in the Kyongsang Basin, indicating that it is extended from the spreading of the East Sea (Japan Sea) and its origin.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.2
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• pp.196-208
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• 2002

Since radio interference has occurred in the TRS frequency band in the south coastal area, Korea from 1994, similar interference has been observed in the mobile-cellular frequency band. Measurement showed that the sources of the radio interference are those from the base stations for digital cellular systems in Japan. This because the receiving frequency of the base stations in Korea is same as the transmitting frequency of the base stations in Japan. Since the distance between Korea and Japan is 240 ~ 300 km, we can conclude that the main reason of the interference is ducting. In this paper a ducting channel is modeled by split-step DMFT algorithm, and simulation results for measured index profile far east coast and west sea area are analyzed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.3
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• pp.301-311
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• 1999

The investigation to evaluate the possible effects of fish behaviour on acoustic target strength was carried out during the 1997 and 1998 hydroacoustic-demersal trawl surveys in the southern waters of Korea.The swimming speed and the target strength of individual, acoustically resolved fished swimming through the sound beam were measured using the split-beam tracking method on board R/V Kaya.The results obtained can be summarized as follows:1. The alongship and athwartship angles between -3dB poionts of a hull mounted 38 kHz split beam tranducer used in these surveys was >$3.76^{\circ}\;and\;6.74^{\circ}$ respectively, and the equal energy contour obtained from the measured beam pattern showed approximately the circular pattern. 2. The swimming speed measured off the south coast of Sorido in 23 January 1997 ranged 0.10 to 0.80 m/s with the average swimming spped of 0.36 m/s, and the target strength ranged -64.8 to -31.7 dB with the average target strength of -52.7 dB. The most dominant species sampled in this survey area were Japanese scaled sardine, Sardinella zunasi and Konoshiro gizzard shad, Konosirus punctatus, respectively.3. The swimming speed measured off the east coast of Kojedo in 24 March 1997 ranged 0.10 to 1.10 m/s with the average swimming speed of 0.40 m/s, and the target strength ranged -64.8 to -51.5 dB with the average target strength of -59.2 dB. The most dominant species sampled in this survey area were Swordtip squid, Photololigo edulis, Konoshiro gizzard shad and Japanese flying squid, Toddarodes pacificus, respectively and the swimming activity of these species seems to be controlled at speeds between 0.20 and 0.60 m/s. 4. The swimming speed measured the south coast of Kojedo in 25 March 1997 ranged 0.10 to 1.40 m/s with the average swimming speed of 0.51 m/s and the target strength ranged -64.3 to -47.7 dB with the average target strength of -55.1 dB. The most dominant species sampled in this survey area were Swordtip squid, Blotchy sillage, Sillago maculata and japanese scaled sardine, respectively and the swimming activity of these species seems to be controlled at speeds between 0.20 and 0.70 m/s.5. The swimming speed measured during morning twilight in the southeastern water of Cheju Island in 11 July 1998 ranged 0.20 to 1.0 m/s with the average swimming speed of 0.53 m/s, and the target strength ranged -65.0 to -47.0 dB with the average target strength of -57.1 dB. The most dominant species sampled in this survey area were Swordtip squid, Black scraper, Thamnaconus modesutus and japanese flying squid, respectively and the tile angle ranged$ +28^{\circ}\;to\;+2^{\circ}$ with the average tilt angle of -8.1$^{\circ}$ showing the downward migration.