• Ocean and Polar Research
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• v.26 no.2
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• pp.351-360
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• 2004

To investigate latitudinal variations in the zooplankton community along the meridian line ($5^{\circ}N-12^{\circ}N$, $131.5^{\circ}W$), we measured temperature, salinity, nitrate, chlorophyll-a and zooplankton at depths above 200 m from July $10^{th}$ to $25^{th}$, 2003. For comparative analysis, data of the physico-chemical properties and chl-a were matched to the two sampling depths (surface mixed layer and thermocline depth-200 m) of zooplankton. Latitudinal differences in the mesozooplankton distribution were mainly influenced by divergence formed at a boundary line formed by currents of opposing directions, consisting of North Equatorial Current (NEC) and North Equatorial Counter Current (NECC). High concentrations of chl-a south of $9^{\circ}N$, caused by equatorial upwelling related nutrients, is thought to be affected by the role of this divergence barrier, supported by relatively low concentrations in waters north of $9^{\circ}N$. The latitudinal differences of the chl-a were significantly associated with the major groups of zooplankton, namely calanoid and cyclopoid copepods, appendicularians, ostracods, chaetognaths, invertebrate larvae, and others. And temperature significantly affected the latitudinal variation of radiolarians, siphonophores, salps and immature copepods. The latitudinal differences in the two factors, temperature and chl-a, which explained 71.0% of the total zooplankton variation, were characterized by the equatorial upwelling as well as the divergence at $9^{\circ}N$. The physical characteristics also affected the community structure and abundance of zooplankton as well as average ratios of cyclopoid versus calanoid copepods. The abundance of dominant copepods, which were consistent with chl-a, were often associated with the carnivorous zooplankton chaetognaths, implying the relative importance of bottom-up regulation from physical properties to predatory zooplankton during the study period. These results suggested that latitudinal distribution of zooplankton is primarily controlled by current-related divergences, while biological processes are of secondary importance in the northeastern Equatorial Pacific during the study period in question.

• The Korean Journal of Malacology
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• v.31 no.3
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• pp.165-170
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• 2015

The presence of predators (excluding starfishes) of disk abalone, Haliotis discus hannai was directly investigated by nine SCUBA divings during February-December 2014 at the coastal areas of Yangjeong, Jukjin and Bongpyeong, Uljin, Korea, where the young disk abalone seedlings were artificially released. The results revealed that a total of six individuals of Neptunea cumingii that were feeding on the young disk abalone were observed within the water depth 10m at the coastal area of Jukjin, of which bottom substrate consists of the relatively high composition rate of rocks (60.3%). Though N. cumingii is well known as a carnivorous predator of diverse marine invertebrates such as live mussels (Mytilus spp.) it is the first report that this predator also feeds on the disk abalones. Thus, our results strongly suggest that the future artificial release projects around Korean coasts necessitate extermination works of predators including newly observed N. cumingii in this study as well as previously known starfishes prior to the releases of young Pacific abalone seedlings.

• Korean Journal of Ichthyology
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• v.20 no.3
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• pp.198-209
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• 2008

During studies of the fish fauna and communities of Mankyeong River, which flows to the Yellow Sea, 14 families in 44 genera and 63 species of freshwater fishes were caught. Zacco platypus (27.7%) was the dominant species and Z. koreanus (11.3%) the subdominant species in this river. Twenty-three species of Korean endemic fishes appeared, and two of these, Pseudopungtungia nigra and Liobagrus obesus, represented endangered Korea species. Community structure of each branch stream was stable, showing appropriate dominant species: Z. koreanus in Jeonju Stream, Z. platypus in Kosan and Soyang Streams, and Carassius auratus in Mankyeong main stream. Three introduced species appeared: C. cuvieri, Micropterus salmoides, and Lepomis macrochirus. Among these introduced species, M. salmoides expanded its territory from midstream to downstream because of its strong carnivorous tendency and it favoring of lentic waters. This distribution of M. salmoides affected the number and distribution of small native freshwater fishes, especially those in the subfamily Acheilognathinae.

• Korean Journal of Ecology and Environment
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• v.38 no.3 s.113
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• pp.289-296
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• 2005

The fish fauna and community structure at 20 stations in streams of the Mt. Biseul were investigated from June 2003 to May 2004. During the study period, 29 species, 25 genera belonging to 9 families were collected. Cyprinid fish occupied 48.3% (14 species) and cobitid fish had 13.8% (4 species). Six species (22.2%) were korean endemic and two species of Micropterus salmoides and Lepomis macrochirus were exotic. It was found that the population density of carnivorous fish (Opsariichthys uncirostris amurensis) increased in the lower-reach of small streams in the Mt. Biseul area since it had been introduced from the other native rivers in the middle 1990s. As the result of analyzing fish community in the surveyed area, the species diversity ranged from 0.553 to 1.023. The findings showed that the Geumpo, Chacheon and Hyeonpung streams had higher species diversity indicies of 0.936 ${\sim}$ 1.023 than the Sincheon and Gisegok streams with 0.553 ${\sim}$ 0.727.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.637-643
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• 2015

The diet composition of juvenile Trachurus japonicus were studied using 195 specimens collected from 2013 (May, June, July, and September) to 2014 (May, June, and July) in the coastal waters of Geumodo, Yeosu, Korea. The size of juvenile T. japonicus ranged from 4.3 to 15.2 cm in body length (BL). Juvenile T. japonicus was carnivorous and crustaceans predators that consumes mainly consumed copepods. Its diet also included small quantities of decapods, cirripedians, nematods, chaetognathans, fishes, amphipods, cumaceans, ostracods and euphausiids. The graphical method for feeding strategy revealed that juvenile T. japonicus is an opportunistic and specialized predator on copepods, especially Corycaeus. affinis, and showed narrow niche width. Juvenile T. japonicus showed ontogenetic diet change. Small size group individuals (4.3-8.0 cm BL) mainly consumed copepods. The portion of this prey item decreased in the large size group (8.0-15.2 cm BL), and this decrease was paralleled with increased consumption of decapods.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.332-341
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• 1989

Stomach contents and microstructures in otolith of Chaenogobius laevis were analyzed for the determination of age, growth and food. By comparaing structural similarity in a series of growth increments from three samples collected in a two-week interval, daily deposition of growth increments in otolith can be validated. Growth in length as daily basis was well represented by Gompertz curve: $L= 5.73{\cdot}\;e^{15.06}(1-e^{-0.0015t})$ for the fish age of $46\~102$ days. Mean growth rate increased from 0.40 mm/day for the age of $50\~60$ days to 0.85 mm/day for the age of $80\~100$ days. Chasnobius laevis showed a carnivorous feeding behavior and its major food items were polychaetes, amphipods and copepods. Small individuals ($15\~30$ mm SL) preyed heavily on copepods as well as polychaetes. However, the portion of copepods in stomach contents was decreased with increasing fish siEe, and this decrease was compensated by an increased consumption of amphipods.

• Korean Journal of Ichthyology
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• v.20 no.1
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• pp.36-44
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• 2008

Feeding habits of Micropterus salmoides were investigated from the stomach contents of specimens ranging from 13 to 511 mm in standard length (n = 419), which are collected in the Lake Okjeong, Korea, 2006 to 2007. M. salmoides is a very strong carnivorous fish eating living organisms such as lots of fishes, small amount of aquatic insects and shrimps. As they grow, the feeding habits changed : they fed mainly on Branchioda in 10 to 20 mm in SL., aquatic insects and small fishes in 30 to 50 mm in SL., fishes including Zacco platypus, Hemiculter eigenmanni and Rhinogobius brunneus over 50 mm. However, among the prey organisms, M. salmoides most preferred living fishes. Analysing ichthyofauna of the Lake Okjeong from 1981 to the present investigation, after and before introduction of M. salmoides, it was showed that there was a certain reduction in fish diversity. Consequently, it is likely to let the strongly fish-eating habit to reduce a diversity of native fishes in the lake.

• Journal of Ecology and Environment
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• v.45 no.1
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• pp.72-77
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• 2021

Background: In 2020, a categorized list of wetland preferences, major habitats, and life forms of 4145 vascular plant taxa occurring in the Korean Peninsula was published by the National Institute of Biological Resources. We analyzed the list and explored the distribution patterns of the five categorized groups according to wetland preference, along with the information on the major habitats and the life forms of the plants belonging to those categories. Results: Out of 4145 taxa, we found that 729 wetland plant taxa (18%) occur in Korea: 401 obligate wetland plants and 328 facultative wetland plants. Among the 729 wetland taxa, the majority (73%) was hygrophytes and the remaining 27% was aquatic macrophytes. Furthermore, almost all of the wetland taxa are herbs; so, woody plants are only 4.7%. The 16 carnivorous taxa distributed in Korea were characterized as obligate wetland plants. Conclusions: We expect the categorized information would promote understanding of the characteristics of the plant species and would be an important source for understanding, conservation, and restoration of wetland ecosystems.

• Journal of Aquaculture
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• v.20 no.4
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• pp.270-277
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• 2007

White spot syndrome virus (WSSV) which is the most serious threat to cultured shrimp around the world has given enormous economic damages to shrimp culture industry every year since it was found from the shrimp ponds in the west coast of the South Korea in 1993. WSSV has strong infectivity as well as virulence and it can be rapidly transmitted among shrimps in ponds by cannibalism of infected ones. Polyculture of shrimps with carnivorous fish has been applied in commercial shrimp farms to suppress or delay the viral outbreak because the fish may selectively eat the moribund shrimps infected by virus. To determine the selective predatory effect of a carnivorous fish, river puffer Takifugu obscurus on white shrimp Litopenaeus vannamei, polyculture trials in laboratory scale of WSSV-infected and non-infected shrimps with river puffer were conducted in concrete round tanks of $28.26\;m^2$ in surface area as followings: 1) juvenile shrimps (B. W. 0.62 g) with 5 months old puffer (B. W. 11.60 g) cultured for 8 days, and 2) sub-adult shrimps (B. W. 6.84 g) with 16 months old puffer (B. W. 85.82 g) cultured for 5 days in order to know the effects according to size difference of cultured animals. In polyculture of juvenile shrimp with 5 months old puffer, survival rates of infected and non-infected shrimps were 46.0% and 89.1% respectively and in that of sub-adult shrimp with 16 months old puffer those were4% and 48% respectively. The results showed that puffer tends to selectively prey on virus infected shrimps among infected and non-infected ones in a limited space with although there is difference in predatory rate with age and density of animals. Regardless of different densities and ages of animals as well as health condition of shrimps, however, there were low differences in daily biomass of shrimp consumed per kg body weight of puffer. This finding suggests that puffer preys on healthy shrimps when moribund shrimps were not sufficient. Therefore, farmers should consider the total biomass of puffer as well as density and stocking time when they stock puffer into shrimp ponds for polyculture.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.192-197
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• 1999

Proximate composition, sterol and $\alpha$-tocopherol ($\alpha$-Toc) contents of 35 species of marine invertebrates (13 species of Bivalvia, 10 species of Gastropoda, 4 species of Cephalopoda, 4 species of Crustacea, 2 species of Ascidacea and 2 species of Holothuroidea), which caught off the coast of Tongyeong of the Southern sea (Nam-Hae), Korea, were determined. Protein content showed relatively high level in herbivorous (seaweed feeder) and carnivorous species such as Gastropoda ($17.2\pm4.30\%$), Crustacea ($16.8\pm4.06\%$) and Cephalopoda ($15.3\pm3.24\%$), but showed low in plankton feeder and mud swallow such as Bivalvia ($11.8\pm2.49\%$), Ascidacea ($8.20\pm1.00\%$) and Holothuroidea ($3.94\pm1.13\%$). Total lipid (TL) content was low in most marine invertebrates, ranged from $0.24\%$ (blue colored sea cucumbers) to $1.96\%$ (sea squirts). Ascidacea contained the largest amount of TL in all samples, while Holothuroidea contained the smallest amount of TL, and other classes contained about $1\%$ of TL. Carbohydrates was rich in plankton feeder and Herbivorous species (seaweed feeder) such as Ascidacea ($6.60\pm4.53\%$), Bivalvia ($3.15\pm1.82\%$) and Gastropoda ($3.02\pm1.61\%$), while poor in carnivorous species such as Crustacea ($0.52\pm0.57\%$) and Cephalopoda ($1.00\pm0.63\%$). Moisture content was highest in Holothuroidea ($92.0\pm1.94\%$) and the lowest in Gastropoda ($77.0\pm1.95\%$): There were negative correlations between moisture and protein content, or TL, between protein and TL content; y= -0.8716x+184.452 (r=-0.87, p<0.001), $y=128.52e^{-0.0601x}$ (r=-0.55, P<0.001), $y=6.3047e^{-0.0904x}$(r=-0.42, P<0.02), respectively. Sterol content was ranged from 56 mg/100 g edible portion of red colored sea cucumbers to 216 mg/100 g edible portion of cockle and was high in the following order; Cephalopoda (148 $\pm$30.0mg)>Bivalvia (121$\pm$35.0mg)>Gastropoda (118$\pm$20.0mg)>Crustacea (116$\pm$31.0mg)>Ascidacea (78.0$\pm$2.00 mg)>Holothuroidea(62.0$\pm$8.00 mg). Crustacea contained 1$\~$2 mg $\alpha$-Toc/100 g edible portion whereas other classes contained trace or less than 1 mg/100 g of edible portion.