• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.1
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• pp.39-45
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• 1997

Subtidal zonation of a cumacean Bodotria biplicata was investigated in the sandy shore surf zone of Dolsando, southern Korea. Three replicate samples were taken with a sledge net at three sites, such as the surface and bottom of 1 m depth and waters edge, at hourly intervals over the neap and spring tide cycles on January 1993 (n=225). B. biplicata, the most dominant cumacean in this area, exhibited peak density at the bottom while about $0.6\%$ of total catch was collected at the surface. Mean density during the neap tide cycle was slightly higher than that during the spring tide cycle. The depth of subtidal zone influenced the total catch of B. biplicata. The changes in density were related to the depth of subtidal zone rather than day-night cycle or ebb-flood tide. The results obtained in this study suggest that the diel vertical migration is not distinct. During both neap and spring tide cycles, B. biplicata attained a density maximum at the same level of about 90 cm below lower low water (LLW). It is likely, therefore, that this species performs shore- and seaward horizontal migration fortnightly. The speed and distance of migration may be directly related to the beach slope and tide range. Ontogenetic differences in subtidal distribution were observed. Juveniles and manca larvae tended to occur lower areas than the adults. Such differences may reduce intraspecific competition for diets.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.2 no.1
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• pp.76-86
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• 1991

Plasma $dopamine-{\beta}-hydroxylase(DBH)$ activity was measured in 37 autistic disorders, 26 atypical pervasive developmental disorders and 23 controls, to elucidate the biological etiology in pervasive developmental disorders. The results are summarized as follows : 1) In the autistic group, the mean plasma DBH activity was significantly elevated compared to the atypical and control groups. The mean plasma DBH activity was also significantly elevated in pervasive developmental disorders(autistic disorder+atypical developmental disorder) compared to control group. 2) In the atypical and control groups, the DBH activity significantly increased with age, but in the autistic group, the DBH activity was not significantly correlated with age. 3) No significant correlation was found between the DBH activity and the severity of psychopathology. These findings support the hypothesis of a possible involvement of brain catecholamine dysfunction in the production of autistic symptoms, and this dysfunction might be due to the abnormal ontogenetic process of DBH activity in autistic disorders.

• Korean Journal of Ichthyology
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• v.25 no.2
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• pp.53-58
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• 2013

Seven individuals (16.1~29.1 mm in length) which were estimated with fishes of genus Abudefduf were collected in Seogwipo, Jeju Island in the summer of 2011 and 2012. Among them, five individuals (20.8~29.1 mm SL) are similar to Abudefduf notatus, based on morphological characters such as yellow transverse band on the body, one small black spot on the base of the pectoral fin, and yellow caudal fin. On the other hand, two individuals (16.1 mm, 17.0 mm SL) differ from them in several light transverse bands and transparent rays of all fins except for pelvic fin, and anterior transparent head with only one (16.1 mm). According to the results of molecular analyses of 578 base pairs of mtDNA 16S rRNA sequences, these individuals correspond to A. notatus adult, with a high bootstrap value of 95% (genetic distance, d=0.002). Therefore, this study shows that the individuals more than 20.8 mm similar to adult body color but the 16.1 mm individual differs to that of adult. We confirm that this species changes to body color during their early life stages. This result regards as a survival strategy to protect themselves against their predator during their early life stages.

• Korean Journal of Ichthyology
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• v.34 no.2
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• pp.102-112
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• 2022

This study investigated dietary habits and intra- and inter-specific food resource partitioning of co-occurring walleye pollock (Gadus chalcogrammus) and Pacific cod (G. macrocephalus) from the waters off the north-eastern coast of South Korea using stomach contents and stable isotopes (δ¹³C and δ¹⁵N) analyses. Both species are mesopelagic carnivores that consumed mainly benthopelagic crustaceans, but teleosts were also abundant in the diet of Pacific cod. Non-metric multidimensional scaling (nMDS) ordination and permutational multivariate analysis of variance (PERMANOVA) of dietary data revealed significant intra- and inter-specific dietary differences, i.e., food resource partitioning. Nitrogen stable isotope values (δ¹⁵N) were similar between walleye pollock and Pacific cod, but carbon stable isotope values (δ¹³C) were significant different, suggesting different trophic positioning. Canonical analysis of principal coordinate (CAP) ordination plot further demonstrated that differences in the type and range of prey ingested by the two species contributed such an inter-specific difference in the diet compositions. Ontogenetic changes in diet compositions were evident. As walleye pollock, they preyed more upon carid shrimps and cephalopods, but no such trend was observed in the diets of Pacific cod. While stable isotope values indicated that large-sized specimens of both species were significantly enriched in ¹⁵N relative to smaller conspecifics thus supporting these data. Consequently, in this study, both methodologies, i.e., stomach contents and stable isotope analyses, provided evidence of inter- and/or intra-specific dietary segregations and trophic niche partitioning between co-occurring walleye pollock and Pacific cod off eastern Korean waters.

• Korean Journal of Ichthyology
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• v.34 no.3
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• pp.172-178
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• 2022

To investigate the feeding habits and trophic level of the blackthroat seaperch, Doederleinia berycoides in the South Sea of Korea, fish samples were collected by a bottom trawl net from fisheries resources survey vessels of NIFS in February, May, August and November 2021. The total length (TL) of these specimens was from 3.3 to 33.1 cm. D. berycoides fed majorly on Teleostei (especially Engraulis japonicus) based on index of relative importance (%IRI=64.4%). D. berycoides underwent an ontogenetic dietary shift. Smaller individuals (<10.0 cm TL) fed mainly on amphipods. The proportion of amphipods decreased as body size increased, whereas the consumption of Teleostei increased gradually. Examination of the feeding habits according to ontogentic feeding patterns in the diets of D. berycoides revealed that the mean weight of prey (mW/ST) continuously increased, while mean number of prey (mN/ST) decreased and then increased. The estimated average trophic level of the D. berycoides was 3.62±0.64, ranging from 3.31±0.52 to 3.79±0.70.

• Korean Journal of Ichthyology
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• v.34 no.3
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• pp.201-207
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• 2022

Total 418 Yellow Croaker Larimichthys polyactis were examined and the range of total length (TL) was 12.0~27.5 cm and average total length was 19.6 cm. The most important prey component in the diets of L. polyactis was Pisces that constituted 46.5% in %IRI (Index of relative importance). Euphausiacea was the second largest prey component. The result of analysis in ontogenetic and seasonal changes significantly exhibited. The proportion of Pisces increased as increasing body size, whereas the consumption of Macrura decreased gradually. The diets also were different among seasons, with the difference particularly being evident between warm (summer and autumn) and cold (winter and spring) seasons. Permutational multivariate analysis of variance (PERMANOVA) revealed significant dietary differences by seasons (P=0.001).

• Korean Journal of Ichthyology
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• v.35 no.3
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• pp.177-182
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• 2023

Total 158 Conger myriaster were examined and the range of Preanal length (PaL) was 8.2~40.1 cm and average Preanal length was 17.3 cm. Proportion of the empty stomach was 30.4% and individuals, which the prey items were found in stomach, were 110. The most important prey component in the diets of C. myriaster was Pisces that constituted 54.4% in %IRI (Index of relative importance). Engraulis japonicus was the most important prey component in Pisces. Macrura was the second largest prey component and Crangon hakodatei was the most important prey component in Macrura. The result of analysis in ontogenetic changes significantly exhibited among three size classes (<15.0 cm, 15.0~20.0 cm, ≥20.0 cm). The proportion of Macrura decreased as increasing body size, whereas the consumption of Pisces increased gradually. As body size of C. myriaster increased, the mean weight of prey per stomach (mW/ST) increased (one way-ANOVA, P<0.05).

• Korean Journal of Ichthyology
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• v.35 no.3
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• pp.183-188
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• 2023

As a result of analyzing 469 Armoured cusk, Hoplobrotula armata, the range of total length was 10.5~63.5 cm and average total length was 30.3 cm. Using the IRI, shrimps were mainly prey component constituted 63.6%, followed by fishes, crabs, anomurans. The result of analysis in ontogenetic changes, shrimps were the most dominant prey in all size groups except for the ≥40.0 cm size group, and fishes were the most dominant prey in the size group of ≥40.0 cm. When the mean number of prey per stomach (mN/ST) and the mean weight of prey per stomach (mW/ST) were analyzed, mN/ST showed a significant difference (one-way ANOVA, P<0.05), but mW/ST did not (one-way ANOVA, P>0.05).

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.340-346
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• 2023

The diet composition of Engraulis japonicus were studied using 1,087 specimens collected by set net fisheries and boat seine fisheries in the coastal waters of Tongyeong, Korea. The size of the specimens ranged from 1.9 to 14.7 cm in fork length. E. japonicus was fed mainly on Copepods, which constituted 50.4% of IRI, followed by Euphausiids, which constituted 47.3% of IRI. Graphical analysis of the diet composition showed that E. japonicus was specialist predator. The result of analysis in ontogenetic changes significantly exhibited among size classes (<8.0 cm, 8.0~10.0 cm, 10.0~12.0 cm, ≥12.0 cm). The proportion of Euphausiids increased, as body size of E. japonicas increased whereas the consumption of Copepods decreased. In the Spring, Autumn and Winter, the diet was dominated by Copepods. In the Summer, the diet was dominated by Euphausiids.

• Journal of Korean Society of Forest Science
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• v.61 no.1
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• pp.8-14
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• 1983

This study was to diagnose the ontogenetic ability of drought tolerance in trees, and was to investigate the seasonal changes in tissue-water relations parameters, ${\pi}_o$, ${\pi}_p$, $E_{max}$, $N_s/DW$, $V_o/W_s$ and $RWC_{(tlp)}$, obtained from P-V curves on the Pinus koraiensis and Abies holophylla shoots. The results obtained are as follows; 1) Seasonal changes of original osmotic pressure at maximum turgot, ${\pi}_o$, were -1.2 to -1.6 MPa in Pinus koraiensis and -1.4 to -1.7 MPa in Abies holophylla. 2) Seasonal changes of osmotic pressure at incipient plasmolysis, ${\pi}_p$, were -1.8 to -2.1 MPa in Pinus koraiensis and -1.6 to -2.1 MPa in Abies holophylla. 3) Seasonal changes of relative water content at incipient plasmolysis, $RWC_{(tlp)}$, were 70 to 77% in Pinus koraiensis and 69 to 85% in Abies holophylla. 4) Seasonal changes of maximum bulk modulus of elasticity at maximum hydration, $E_{max}$, were 2.2 to 6.3 MPa in Pinus koraiensis and 3.1 to 7.9 MPa in Abies holophylla. 5) Seasonal changes of number of osmoles of solute in symplasm versus dry weight, $N_s/DW$, were 0.5 to 1.3 in Pinus koraiensis and 0.3 to 1.0 in Abies holophylla. 6) Seasonal changes of original osmotic water volume versus total water volume (symplasmic and apoplastic water), $V_o/W_s$, were 55 to 65%r in Pinus koraiensis and 40 to 65% in Abies holophylla. Consequently, as the comparative values of ${\pi}_o$, ${\pi}_p$, $E_{max}$, $N_s/DW$, $V_o/W_s$, and $RWC_{(tlp)}$, it might be suggested that Abies holophylla shoot could have more or less a greater ability of drought tolerance as compared with Pinus koraiensis shoot.