• Korean Journal of Ichthyology
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• v.34 no.1
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• pp.64-70
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• 2022

The Eyebar goby, Gnatholepis cauerensis is reported firstly from Korea, based on four specimens (36.3~47.1 mm in SL) collected at depth range of 12~16 m in the southern coastal waters of Jejudo Island, Korea. They are characterized by having mostly ctenoid scales on body, head including cheek, opercle, and middle of predorsal region with cycloid scales, and a unique coloration of yellow blotch with marginally black marking above pectoral fin base as well as transverse black bar below eye. A new Korean name, "Geom-eun-nun-ddi-mang-dug", is proposed for the species.

• Ocean and Polar Research
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• v.34 no.2
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• pp.111-123
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• 2012

To understand the phytoplankton community in the eastern part of the Yellow Sea (EYS), in the summer, field survey was conducted at 25 stations in June 2009, and water samples were analyzed using a epifluorescence microscopy, flow cytometry and HPLC method. The EYS could be divided into four areas by a cluster analysis, using phytoplankton group abundances: coastal mixing area, Anma-do area, transition water, and the central Yellow Sea. In the coastal mixing area, water column was well mixed vertically, and phytoplankton was dominated by diatoms, chrysophytes, dinoflagellates and nanoflagellates, showing high abundance ($>10^5\;cells\;l^{-1}$). In Anma-do coastal waters characterized by high dominance of dinoflagellates, high phytoplankton abundance and biomass separated from other coastal mixing area. The southeastern upwelling area was expanded from Jin-do to Heuksan-do, by a tidal mixing and coastal upwelling in the southern area of Manjae-do, and phytoplankton was dominated by benthic diatoms, nanoflagellates and Synechococcus group in this area. Phytoplankton abundance and biomass dominated by pico- and nanophytoplankton were low values in the transition waters and the central Yellow Sea. In the surface of the central Yellow Sea, high dominance of photosynthetic pigments, 19'-hexanoyloxyfucoxanthin and zeaxanthin implies that haptophytes and cyanobacteria could be the dominant group during the summer. These results indicate that the phytoplankton communities in the EYS were significantly affected by the formation of tidal front, thermal stratification, and coastal upwelling showing the differences of physical and chemical characteristics during the summer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.2
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• pp.173-179
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• 2012

The common squid $Todarodes$ $pacificus$ is a dominant species in Korean waters, where it is captured preponderantly by the angling fishery. The spawning and nursery grounds of $T.$ $pacificus$ extend from the southern East Sea to the northern East China Sea. Consequently, the environmental conditions in this area during the spawning and nursery seasons might affect the abundance of $T.$ $pacificus$. This study, analyzed the relationship between the distribution of zooplankton and the abundance of $T.$ $pacificus$ and variation in the squid angling fishing grounds in Korean waters. There was a positive relationship between the fluctuations in zooplankton and the catch per unit effort (CPUE; $kg{\cdot}day^{-1}{\cdot}person^{-1}$) of the angling fishery in the East Sea of Korea. The main fishing season is from July to December and the CPUE was closely related to the zooplankton biomass in April in the East Sea. Recently, the center of the squid jigging ground has moved drastically from the area around Ulleung Island to the northern East Sea. We postulate that the fishing grounds of the squid angling fishery will move farther north with climate change.

• ALGAE
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• v.36 no.1
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• pp.25-36
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• 2021

The mixotrophic dinoflagellate Tripos furca causes red tides in the waters of many countries. To understand its population dynamics, mortality due to predation as well as growth rate should be assessed. Prior to the present study, the heterotrophic dinoflagellates Noctiluca scintillans, Polykrikos kofoidii, Protoperidinium steinii, and mixotrophic dinoflagellate Fragilidium subglobosum were known to ingest T. furca. However, if other common heterotrophic protists are able to feed on T. furca has not been tested. We explored interactions between T. furca and nine heterotrophic dinoflagellates and one naked ciliate. Furthermore, we investigated the abundance of T. furca and common heterotrophic protists in coastal-offshore waters off Yeosu, southern Korea, on Jul 31, 2020, during its red tide. Among the tested heterotrophic protists, the heterotrophic dinoflagellates Aduncodinium glandula, Luciella masanensis, and Pfiesteria piscicida were able to feed on T. furca. However, the heterotrophic dinoflagellates Gyrodiniellum shiwhaense, Gyrodinium dominans, Gyrodinium jinhaense, Gyrodinium moestrupii, Oblea rotunda, Oxyrrhis marina, and the naked ciliate Rimostrombidium sp. were unable to feed on it. However, T. furca did not support the growth of A. glandula, L. masanensis, or P. piscicida. Red tides dominated by T. furca prevailed in the South Sea of Korea from Jun 30 to Sep 5, 2020. The maximum abundance of heterotrophic dinoflagellates in the waters off Yeosu on Jul 31, 2020, was as low as 5.0 cells mL-1, and A. glandula, L. masanensis, and P. piscicida were not detected. Furthermore, the abundances of the known predators F. subglobosum, N. scintillans, P. kofoidii, and Protoperidinium spp. were very low or negligible. Therefore, no or low abundance of effective predators might be partially responsible for the long duration of the T. furca red tides in the South Sea of Korea in 2020.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.151-162
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• 1980

To clarify the dispersion of pollutants introduced in the coastal region, a series of current measurements, the drogue and drift bottle experiments as well as the dye diffusion experiments were carried out in Onsan Bay and in the coastal waters of Ubong-ri near Ulsan. In the southeastern coastal region of Korean peninsula, that is, in the outside of Onsan Bay, the flood tidal current flows south-south-westward, and the ebb current flows north-north-eastward at a maximum speed of 1.0-1.1 knots at spring tide. In an inlet south of Cape Ubong, an anticyclonic eddy of 1 km in diameter is usually formed during both flood and ebb flows. The tidal current predominates in Onsan Bay at around spring tide. The maximum speed around spring tide was observed to be approximately 0.14 knot, while it was slower than 0.1 knot and variable at neap tide when the wind drift current played an important role. The flood tidal current flows westward while the ebb flow flows eastward in the northern region of the bay. The flood tidal current in the southern region of the bay flows west-north-westward, while the ebb current east-north-eastward. Wind drift currents in the coastal region of southern Korea are generally deduced to be southward in winter, the monthly mean speed being approximately 0.1 knot. Dye solution released at the northwestern corner in Onsan Bay was transported by eastward ebb tidal current toward the mouth of the bay dispersing by the wind. The apparent diffusion coefficient at 150 minutes after release in the bay was calculated to be $4.4\times10^4\;cm^2.sec^{-1}$, whereas that in the anticyclonic eddy was more or less smaller.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.666-684
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• 2019

The horizontal distributions of eggs and larvae of chub mackerel Scomber japonicus were extensively surveyed in the vicinity of Korean waters between 31°75'N and 36°50'N during May and June in 2016 and 2017 (total of four surveys). We used a coupled bio-physical model (DisMELS) that combines an individual-based model (IBM) incorporating vertical migration of larvae and temperature-dependent survival to understand transport processes in the early life stage. Using the distributions of eggs and larvae from surveys, the potential spawning grounds were estimated at the northwest and southeast of Jeju Island and the central East China Sea in May, and at the southwestern East Sea and southern West Sea in June by running the model backward in time. In forward experiments within 30 days from the backward results, most larvae were transported to both the Korean and Japanese sides of the East Sea through the Korea Strait. However, the larvae released in the central East China Sea were transported to the Japanese side only, while those released in the southern West Sea were retained within that region. The survival rates at 30 days after release based on the simulation incorporating temperature-dependent survival throughout May and June were 29.7% in 2016 and 28.8% in 2017.

• 한국해양학회지
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• v.27 no.2
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• pp.91-100
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• 1992

For the study on the structure and characteristics of the primary production system in the southern waters of the East Sea, chlorophyll, phytoplankton standing stocks. nutrients and hydrographic properties were investigated and analyzed in conjunction with measurement of C-14 based primary productivity. The primary productivity was relatively high in comparison with the previous studies, ranging from 284 to 4,574 mgC$.$m/SUP -2/$.$day /SUP -1/ and averaged to be 2,000 mgC$.$m/SUP 02/$.$day/SUP -1/. The standing stocks within the euphotic zone were fairly high, but ambient inorganic nitrogenous nutrient concentrations were too low to support the high production. This implied that there might be active recycling of nitrogenous nutrients by heterotrophic processes and the upward flux of nutrients by vertical mixing. Subsurface chlorophyll maxima were continuously observed in the lower parts of the euphotic layer and the depth coincided with the nutricline rather than isopycnal surfaces, supporting the view that chlorophyll distributions and primary production were primarily influenced by nutrient supply. Despite low nutrient concentrations, phytoplankton standing stocks and production were fairly high and the fraction of autotrophic nano- and picoplankton production was significant.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.3
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• pp.219-229
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• 1984

Physical and chemical survey on western channel of the Korea Strait was made using oceanographic data from July 25 to July 31, 1983. Four water types were distinguished at western channel: runoff of the Nakdong River, Tsushima Current Waters, Keoje Coastal Waters, and Ulsan Coastal Waters. Influence of the Nakdong River was greater at Southern East Coast near Yeong-Do Island in Pusan than at Keoje Coast. General characteristics of these four water types were as follows : For runoff of the Nakdong River, transparency was within 3 m, water colour chinese yellow (number 11), surface temperature $18{\sim}19^{\circ}C$, salinity less than $31\%0$, surface dissolved oxygen (D.O.) $4.5{\sim}5.0ml/l$, contents of phosphate $0.25{\sim}0.5{\mu}g-at./l$ ; these values were the highest among these four water types. For Tsushima Current waters, transparency was greater than 15 m, waters color blue (number $2{\sim}4$), surface temperature about $23^{\circ}C$, salinity $32{\sim}33\%0$, and surface D.O. greater than 5,0 ml/l. Phosphate, nitrate and silicate were less than 0.25, 2.0, and $2.5{\mu}g-at./l$, respectively; these values were the lowest among these four water types. Keoje Coastal Waters had low temperature ranging $20{\sim}21^{\circ}C$ at surface, and high salinity greater than $33\%0$. D.O. was less than 5.0 ml/l, phoshpate, $0.5{\mu}g-at./l$ nitrate and silicate were less than $3.5{\mu}g-at./l$. Ulsan Coastal Waters had the lowest surface temperature among these four types; surface temperature was less than $16^{\circ}C$, salinity greater than $33.5\%0$, and D.O., phosphate and nitrate had very high values. It seems that these high values resulted from upwelling phenomena.

• Korean Journal of Ichthyology
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• v.31 no.4
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• pp.255-258
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• 2019

Fifteen gobids specimens first collected from the southern coastal waters of Tongyeong, Gyeongsangnam-do, were identified as the Suruga fundicola from Korea. The species, representing a new Korean record, is characterized by having VII-I, 16~17 dorsal fin rays, I, 15~16 anal fin rays, 37~42 lateral line scales, notably large eye and narrow interorbital space, scaleless cheek and opercle, no babel, teeth rather strong, and 6~7 dusky spots on sides. A new Korean name, "Keun-nun-mangduk-sok" and "Keun-nun-mang-duk" is proposed for the genus and species, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.3
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• pp.140-147
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• 2002

We investigated the temporal variations in the heterotrophic dinoflagellates (hereafter HTD), tintinnid ciliates(TC), and naked ciliates(NC) from August to November 1999 in the coastal waters off the southern Saemankeum areas where a huge red tide dominated by Cochlodinium polykrikoides/Gymnodinium impudicum was first observed in 1998. We took water samples from 2-5 depths of 4 stations in each of the 5 cruises and then measured the species composition and abundances of HTD, TC, and NC The maximum species numbers and densities of HTD, TC, and NC(11, 12, and 10 cells $m\ell$$^{-1}$ , respectively) were observed when the density of diatoms was highest (August 10), while the lowest values (1.0, 0.5, and 2.4 cells $m\ell$$^{-1}$ , respectively) were found when the red tide dominated by C. polykrikoides/G. impudicum took placed (October 18). On August 10 and November 11 when diatoms dominated the abundance of phytoplankton, the correlation coefficients between TC, NC and diatoms were relatively high. However, On September 16 and October 18 when autotrophic+mixotrophic dinoflagellates(ATD+MTD) were abundant, the correlation coefficients between HTD and ATD+MTD were relatively high. The large HTD Noctiluca scintillans was the most dominant heterotrophic protists during the C. polykrikoides/G. impudicum red tide on October 18. N. scintillans has been known to feed on the prey cells when the swimming speeds of C. polykrikikoides/G. impudicum markedly reduced at the decline stage of the red tide. Therefore, N. scintillans could be effective grazers on C. polykrikoides/G. impudicum. The maximum densities of HTD, TC, and NC in the study area were fairly lower than those obtained in the waters off Kohung-Yeosu areas in the summer-fall, 1997. The results of the present study provide the basis of understanding predator-prey relationships between dominant phytoplankton and heterotrophic protists and the roles of the protist grazers in bloom dynamics in the waters off the western Korea.