• Korean Journal of Ecology and Environment
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• v.38 no.2 s.112
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• pp.188-195
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• 2005

The dynamics of the fish community in the Lake Hoengseong region, Korea, were investigated from April 2000 to November 2004. During the surveyed period 39 species belonging 10 families were collected, and there were 17 Korean endemic species (43.59%) including Rhodeus pseudosericeus. Dominant species were Acheilognathus lanceolatus (20.10%), Zacco platypus (15.94%), Z. temmincki (6.92%), Carassius cuvieri (6.33%), A. rhombeus (6.18%), Pungtungia herzi (5.13%), and Pseudorasbora parva (4.93), In the comparison community of fish according to ecotype by each studied years, benthic fished are gradually decreasing and pelagic fishes creasing. Also, according to the fish distribution, the fish community of each studied years was divided into 3 groups by UPGMA. Being based on the fish community, similarity analysis results of each artificial lakes and this lake were divided 2 groups by water system, and divided again 3 groups in the same water system. Fish Community of the Lake Hoengseong was similar with that of the Lake Chuncheon and Cheongpyeong of the Bukhan-River.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.2
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• pp.107-117
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• 2012

Korean large purse seine fishery catches chub mackerel, sardine, jack mackerel, Spanish mackerel, etc. which are mainly pelagic fish species. The proportion of chub mackerel was 60% over in Korean large purse seine fishery. Sea surface temperature (SST) increased $0.0253^{\circ}C$ per year and total rising rate was $0.759^{\circ}C$ from 1980 to 2009 in the southern sea of Korea, where is mainly fishing grounds of Korean large purse seine. It was that p<0.01 level was statistically significant. It is northward movement that the center of fishing grounds of chub mackerel by Korean large purse seine fishery moved 4.57km/yr. It was rapidly northward movement about 7.1km/yr, 8.13km/yr to move Spanish mackerel and bluefin tuna fishing grounds. However, the fishing grounds of jack mackerel were moved further south in the 2000s than the 1980s. Catch of tunas and bluefin tuna consistently increased in Korean waters. There was a significantly positive correlation between SST and catch of bluefin tuna in the fishing grounds of Korean waters.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.71-77
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• 1999

Phytoplankton communities were investigated 13 times during the period from November, 1995 to December, 1996 in the coastal area of Kori. A total of 162 taxa (including unidentified species) were observed； 120 diatoms, 3 silicoflagellates, 34 dinoflagellates, 2 euglenoids, 1 chlorophyte and 2 unidentified microflagellates. A diatom species, Skeletonema costatum (Greville) Clove dominated all the year round. The standing stocks of phytoplankton ranged from 94 cells/ml in August to 1059 cells/ml in July. The peaks of standing stocks occurred in February and July. The effects of thermal effluent to the phytoplankton communities changed seasonally and might affect increasing the standing stocks where about 1 ∼ 3 km from the discharge of Kori Nuclear Power Plant in autumn and winter. But the effects of thermal effluent must be negative in summer.

• Ocean Science Journal
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• v.40 no.3
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• pp.177-182
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• 2005

The process of embryogenesis and larval development of the asteroid sea star Asterias amurensis $(U{\ddot{u}}tken)$ was observed, with special attention paid to morphological change and larval duration. In reproductive season, mature sea stars were collected under floating net cages, located in Tongyeong, southern Korea. The mature eggs are $138\;{\mu}m$ in average diameter, semi-translucent and orange in color, sperms in good condition appear light cream to white-gray in color. Embryos develop through the holoblastic equal cleavage stage and a wrinkled blastula stage that lasts about 9 hours after fertilization. Gastrulae bearing an expanded archenteron hatch from the fertilization envelope 22 hours after fertilization. At the end of gastrulation, rudiments of the left and right coelom are formed. By day 2, larvae possess complete alimentary canal and begin to feed. At this stage, the larva is called early bipinnaria. In 6-day-old larvae, the pre- and post- oral ciliated bands form complete circuits and the bipinnarial processes start to develop. By day 12, the lateral and anterior projection of the larval wall processes along the ciliated bands begins to thicken and curl, and the ciliated bands become more prominent. By day 32, early brachiolaria are presented with three pairs of brachiolar arms. Advanced brachiolaria with a well-developed brachiolar complex (three pairs of brachia and central adhesive disc) occur 6 weeks after fertilization. In the field, spawning of the sea star was observed in April to May, settlement form larvae and just settlements seem to occur from June to July, and early juveniles occur from August to September. Although we had not described the end of brachiolaria stage, it can be tentatively estimated that the duration of the pelagic stage of A. amurensis is 40 to 50 days.

• Economic and Environmental Geology
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• v.37 no.2
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• pp.255-267
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• 2004

Deep-sea surface sediments acquired by multiple corer from 69 stations in the Clarion-Clipperton fracture zone of the northeast equatorial Pacific, were analyzed for shear strength properties to understand sedimentological process. The pelagic red clay from northern part of study area shows low average shear strength(4.4 kPa), while the siliceous sediment from middle area shows high(6.3 kPa). The calcareous sediment from southern area shows very low average shear strength(3.4 kPa), and transitional sediment between middle and southern area shows intermediate value(3.8 kPa) between siliceous and calcareous sediment. The depth profiles of average shear strength of pelagicred clay show gradual increment with depth due to decrease of water content with depth by general consolidation process. On the other, abrupt increment of average shear strength with depth in siliceous sediment is related to sedimentary hiatus. The very low shear strength in calcareous sediment is linked to very high sedimentation rate ofsouthern area compared with other study area.

• Economic and Environmental Geology
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• v.35 no.2
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• pp.171-177
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• 2002

Two piston-core sediments, obtained from the southwestern margin of the Ulleung Basin in East Sea, are analyzed to investigate the stratigraphy and sedimentary environment of the Late Quaternary. The cores consist mainly of cuddy sediments with silty sands, lapilli tephra and ash layers. The chronostratigraphic correlation with known eruption ages reveals that the core sediments contain the stratigraphic document over the past 46.1 kyr and the sedimentation rates during the last glacial period were relatively higher (12.1-14.9 cm/kyr) than those in pelagic ocean. Several sedimentary facies, mainly affected by turbidity currents, are commonly present in the core interval accumulated during the oxygen-isotope stage 2. Many of horizontal voids, which are thought to have formed by gas expansion, are observed in fore 00GHP-07. The total organic carbon (TOC) contents of the core sediments are noticeably high (average 1 .8%). Particularly, these TOC valuers increased during Termination I, suggesting that dering this time interval the sedimentary environment of the study area was changed to more anoxic.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.3
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• pp.184-195
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• 2005

A preliminary quantitative model of the trophic structure in Gwangyang bay, Korea was obtained using ECOPATH and data from relevant studies to date in the region. The model integrates and analyzes biomass, food spectrum, trophic interactions and the key trophic pathways of the system. The bay model comprises 9 groups of benthic primary producer, phytoplankton, zooplankton, benthos, bivalve, pelagic fish, demersal fish and piscivorous fish. The total system throughput was estimated at $2.4\;kgWW/m^2/yr$, including a consumption of $41\%$, exports of $9\%$, respiratory flows of $24\%$ and flows into detritus of $26\%$. All of which originate from primary producers measured at $52\%$ and detritus of $48\%$. The total biomass was seen to be high compared to the levels of Somme, Delaware, Chesapeake Bays and Seine Estuary. This seems to be possibly due to artificial bivalve aquaculture and overestimation of benthos and benthic primary producer groups. The deviation can be calibrated by neglecting aquaculture and decreasing the habitat area for the groups. The trophic network of the bay shows a low level of recycling and organization as indicated by Finn's cycling index $3.3\%$, Ascendancy $3.1\;kgC/m^2/yr$ bits, Capacity $5.1\;kgC/m^2/yr$ bits and Redundancy $2.2\;kgC/m^2/yr$ bits. A high relative ascendancy of $62\%$ and a low internal relative ascendancy of $18\%$ indicate the system is not fully organized and stable towards disturbances, depending upon external connections. Although the model should be continuously provided with field data and calibrated further in depth, this study is the first trophic model applied to the region. The model can be a useful tool to understand the ecosystem in a quantitative manner.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.4
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• pp.320-324
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• 2000

Fish were collected by an otter trawl from December 1995 to July 1997 in Suyoung Bay, Korea. The temperature ranged from $12.0 to 27.7^{\circ}C$ and salinity ranged from $31.2 to 34.45{\%}_{\circ}$, The number of species, number of individuals and biomass of fish collected were 52 species, 2,006 individuals and 63,580 grams, respectively. The demersal fish predominated in the number of individuals ($90.4{\%}$) and biomass ($81.4{\%}$). The diversity index (H') was $1.5{\~}2.6$, The dominant species were Platycephalus indicus, Limanda yokohamae, Siliago sihama and Hexagrammos otakii.

• The Korean Journal of Zoology
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• v.15 no.2
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• pp.87-91
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• 1972

For the geographical distribution of Primno macropa it was distributed over all stations investigated, except surface tow in East China Sea, through all seasons. It is believed that this species is most cosmopolitan species in the western North Pacific. Veritical distributional range of P. macropa indicates at depths from surface to more than 1,500m and most deeper recored for the vertical occurrence was obtained from depth of 1,650-2,220m in Station 229 $(34^\\circ 44.3'N, 140^\\circ 04.4'E)$, off Nojima-Zaki, Central Japan. For the vertical distributional and migrational pattern it is a typical diurnal migrant in the western North Pacific; at depths from 100m to 500m at night and 400m to 700m at day in Oyashio population, and from surface to 200m at night and from 100m to 300m at day in Kuroshio population. In Kuroshio area, the population of P. macropa was distributed in somewhat shallower layers than in Oyashio area and it is suggested that the populations is different in region and season according to their stages consisting the population.

• Ocean and Polar Research
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• v.27 no.4
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• pp.381-395
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• 2005

The spatial distributions of macrobenthic communities in Masan Bay were investigated during summer and winter, 2004. A total of 104 species were sampled with mean density of $448ind./m^2$ and biomass of $77.1g/m^2$ in winter. In summer, a total of 107 species occurred with $485ind./m^2$ and a biomass of $94.5g/m^2$. The most dominant species in winter were Paraprionospio pinnata (24.2%) among polychaetous worms and Theora fragilis (14.1%) among molluscs, but they were replaced in summer by Prionospio chirrifera (20.4%) and Lumbrineris longifolia (14.5%). The difference in species composition and abundance of benthic communities between the two seasons was due to the hypoxia in the bottom layer of the inner bay during summer, which defaunated the macrofauna of the sediments. In the winter when DO concentration increased to normoxia, the pelagic larvae of benthic fauna settled in the soft sediments, but there was a spatial gradient in values of total biomass, density, and H' and benthic pollution index (BPI): higher values were found toward the mouth of the bay. The multivariate analyses like the cluster analysis and MDS ordination showed that Masan Bay could be divided into two or four stational groups in winter and summer whether the hypoxia occurred or not. Group I consisted of sites at the inner bay and central area and Group II, sites at the bay mouth. In summer the inner bay area could be further divided into the shallow impoverished area and the deeper abiotic one.