• Journal of Marine Life Science
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• v.9 no.1
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• pp.47-52
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• 2024

Light is a major external environmental factor that influences the circadian rhythm of photosynthetic organisms and various physiological phenomena, such as growth, maturation, and behavior. The number of light-reaching organisms changes depending on the season and atmospheric conditions, and the intensity and wavelength of light differ depending on the organisms inhabiting the environment. Altered light changes the circadian rhythm of fish, which is controlled by clock genes, such as period 2 (Per2), cryptochrome 1 (Cry1), and melatonin. In this study, we set the zeitgeber time (ZT; 14 light-10 dark, LD) based on the actual sunrise and sunset times and examined Per2 and Cry1 activities, levels of aralkylamine N-acetyltransferase (AANAT), and melatonin in Pholis nebulosa, a drifting seaweed species exposed to irregular light. Per2 and Cry1 levels increased during the daytime and decreased after sunset. The AANAT levels decreased during the daytime and increased during the night. Melatonin concentration was highest around midnight (ZT21, 23:30), but exhibited similar concentrations during the daytime. While the activity of Per2, Cry1, and AANAT levels exhibited a typical circadian rhythm observed in most vertebrates, melatonin concentrations did not show a significant difference between the daytime and nighttime. These findings provide insights into the circadian rhythm patterns of organisms exposed to irregular light environments, such as P. nebulosa, which differ from those of typical fish species.

• Korean Journal of Ichthyology
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• v.36 no.2
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• pp.164-173
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• 2024

We collected fish from the intertidal zone of Seonyu-do Island in order to find out the composition of fish species by using hand net and kick net from March to October 2022. During the investigation period, a total of 2,707 individuals from 9 Orders, 19 Families, 45 Species were collected, and the dominant species was identified as Nuchequula nuchalis and the subdominant species was Favonigobius gymnauchen. By family group, the largest number of fishes in the Gobiidae were 13 species, followed by the Scorpaenidae and the Stichaeidae were 4 species. In this study, genus Clariger was discovered for the first time off the West sea, and it is estimated that fish living on the southern coast are moving northward due to an increase in the water temperature of the West Sea and detailed research is needed.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.873-878
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• 2024

We collected rat feces by group period after oral administration of fructooligosaccharides and fruit and vegetable complex extracts for 2 weeks in the Sprague-Dawley rat model of loperamide-induced constipation and analyzed trends in changes in the intestinal microbiome. Microbial composition analysis was performed on Fractoologosaccharide and fruit and vegetable complex extracs(FVCE), by 16S rDNA cloning and pyrosequencing to obtain basic data for the standardization and systematization of the FVCE manufacturing process. Microbial analysis of the prokaryotic community revealed a slight difference in microbial verrucomicrobiota was dominant at the phylum level. At the genus level, prevotella and muribaculaceae showed further differences at the species level. These results suggest that the microbial community used affects the quality of fruit and vegetable complex extracs(FVCE) produced. Thus, a stable microbial community must be maintained for the production of fruit and vegetable complex extracs(FVCE) with consistent quality.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.4
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• pp.467-478
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• 2024

The fish assemblage characteristics in the coastal waters of Sinchang-ri in the Western region of Jeju Island were determined using trammel net samples collected from 2012 to 2022. During the survey period, 81 fish species (43 families, 12 orders) were identified. Tetraodontiformes (4 families, 9 species) and Perciformes (26 families, 57 species) accounted for 84% of the total number. Annual species variation was highest in 2017 and 2019 (36 species) and lowest in 2015 (26 species). Seasonal species variation was higher in summer (peak, 58 species) than winter (peak, 41 species). The number of individuals (1,509) and biomass (446.5 kg) peaked in August (summer) and were lowest in February (winter; 415 individuals, and 150.7 kg). 41 (50.6%) subtropical fish species were identified, and the number of species was highest in 2020 {21 (61.8%) and lowest in 2014, 2017 [16-18 (47.1-47.4%)]}. Subtropical fish species, individuals and biomass were significantly correlated with environmental factors (summer temperatures) at the sampling sites. Scarbreast tuskfish Choerodon azurio, balloon fish Diodon holocanthus, flag fish Goniistius zonatus, bluestriped angelfish Chaetodontoplus septentrionalis, hairy stingfish Scorpaenopsis cirrhosa, threeline grunt Parapristipoma trilineatum, and blackfin sweeper Pempheris japonica were the dominant species of subtropical fish in the study sites.

• Korean Journal of Environment and Ecology
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• v.31 no.6
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• pp.508-519
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• 2017

There have been many studies on monitoring of biodiversity changes and preservation of Gwangneung Forest Biosphere Reserve (GFBR) in South Korea in recognition of the rare ecosystem that has been preserved for a long period. However, there are few studies on diversity and community characteristics of benthic macroinvertebrates as an indicator of stream health of GFBR. The purpose of this study was to assess the water quality of Bongseonsa Stream that penetrated through Gwangneung Forest and the nearby torrents by analyzing the benthic macroinvertebrates community during April to September 2016. The investigation collected a total of 114 species of benthic macroinvertebrates belonging to 56 families, 17 orders, 8 classes, and 5 phyla from the Bongseonsa Stream and Kwangneung Stream. Ephemeroptera and Trichoptera were the largest groups in species diversity with 30 species (32.3%) and 16 species (17.2%), respectively, and Tubificidae sp., Baetis fuscatus, Antocha KUa, and Cheumatopsyche brevilineata, which usually habit in contaminated streams, appeared frequently. Among the feeding function groups, the gatherers and hunters appeared relatively frequently, and the shredders and scrapers appeared frequently in the torrents. Among the habitat oriented groups, the clingers and burrower appeared more frequently and represented the microhabitats in the shallow areas. The result of the analysis of benthic macroinvertebrates community showed that the dominant index was $0.48{\pm}0.10$ in average while it was lowest with 0.33 in GS 8 of the Gwangneung Forest torrent and highest in BS 1 of Bongseonsa Stream. The diversity and richness indices were inversely proportional to the dominant index and were 2.53 and 4.22, respectively, in GS 8 where the dominant index was low. The result of the analysis of community stability showed that area I, which had high resistance and restoration, was high in Bongseonsa Stream while the area III, which had low resistance and restoration, was high in Gwangneung Forest, indicating that the water system in Gwangneung Forest had a wider distribution of specifies sensitive to agitation. The biological water quality assessment showed ESB of $50.88{\pm}17.69$, KSI of $1.11{\pm}0.57$, and BMI of $78.55{\pm}11.05$. GS 8 of Gwangneung Forest torrent was judged to be the highest priority protective water area with the best water environment and I class water quality with ESB of 63, KSI of 0.55, and BMI of 89.9. On the contrary, BS 1 of Bongseonsa Stream was judged to be the high priority improvement area that had the lowest water quality rating of III with ESB of 25, KSI of 2.13, and BMI of 62.7. Although the diversity of water beetle was higher in the water system of nearby Bongseonsa Stream than the water system inside the Gwangneung Forest, the annual community structure appeared to have distinct differences.

• Korean Journal of Environment and Ecology
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• v.30 no.3
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• pp.353-368
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• 2016

This study surveyed the diversity and distributional characteristics of benthic macroinvertebrates and freshwater fish during the period from April to October, 2015 in Seonun Mountain Provincial Park. As a result, a total of 78 species of benthic macroinvertebrates belonging to 50 families, 16 orders, and four phyla were observed in Seonun stream; additionally, 25 species of freshwater fish belonging to six families were identified in all the investigated sites. Among benthic macroinvertebrates, Ephemeroptera(13 spp.: 22.81%) was the largest group in terms of species richness. In the FFGs, gathering-collectors(30 spp.: 36.14%) were relatively larger as represented by Ephemeroptera that usually inhabit fast flowing streams. In the HOGs, clingers(23 spp.: 29.49%) and burrowers(17 spp.: 21.79%) were the dominant groups. For both EPT ratio and ESB index, site 8 appeared to be the highest with 44.44% and 72 marks respectively, while the sites 4 and 9 showed relatively lower rates and indices. According to the results of evaluation, site 8 needs to be designated as the highest protection area while the sites 4 and 9 may be designated as target areas for preferential improvement. According to the analysis of fish community, the dominant species was Zacco teminchkii(333 inds.: 36.80%), and the dominant index was the lowest(0.24) and diversity index was the highest(1.81) at site 8, which therefore represents a stable freshwater fish community. In this survey, six Korean endemic species were identified: Ephemera separigata, Neoperla coreensis, Rhodeus uyekii, Squalidus gracilis majimae, Microphysogobio yaluensis, and Iksookimia koreensis. Also, three species belonging to the management of exportable group(Davidius lunatus, E. separigara, N. coreenis) were observed. Two habitat specific species: Thraulus grandis and Anguilla marmorata, were found for the first time in Gochang area and marked on the Korean distribution map through discussion.

• The Korean Journal of Ecology
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• v.24 no.5
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• pp.315-322
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• 2001

Seasonal production and nutrient concentrations of mushrooms in an Quercus acutissima forest were studied from 1999 to 2000. Thirty 2×2m quadrats were established randomly in the study area. 114 species of mushrooms were identified during the study period. Although mushrooms occurred from May to November in each year, the highest biomass production occurred in August. Seasonal dominant species was Lactarius violascens in June, R. bella and L. violascens in July, Marasmius siccus in August, Cortinarius tenuipes in September, Lepista nuda and C. tenuipes in October, respectively. Annual production of mushrooms in 1999 and 2000 were 84.8 kgDW·ha/sup -1/·yr/sup -1/ and 86.7 kgDW·ha/sup -1/·yr/sup -1/, respectively. Seasonal production was27.1kg/ha for July, 35.9kg/ha for August and 17.1 kg/ha for September, 3.7kg/ha for October, respectively. Seasonal dominant species in biomass was Russula alboareolata in June, R. bella in July, R. pseudodelica in August and September, Lepista nuda in October, respectively. R. pseudodelica showed the highest biomass in the study area, which is 17.5% of the total biomass. Average concentration of nutrients in mushrooms was 45.2mg/g for N, 1.5 mg/g for P, 29.6 mg/g for K, 0.2 mg/g for Ca and 0.8 mg/g for Mg, respectively, which were much higher than those in the leaf litter. Nutrients absorbed by mushrooms in 2000 was 4,163.1 g·ha/sup -1/·yr/sup -1/ for N, 130.1 g·ha/sup -1/·yr/sup -1/ for P, 2,568.2 g·ha/sup -1/·yr/sup -1/ for K, 12.4 g·ha/sup -1/·yr/sup -1/ for Ca, 68.5 g·ha/sup -1/·yr/sup -1/ for Mg, respectively.

• Korean Journal of Ichthyology
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• v.22 no.3
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• pp.168-178
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• 2010

Fish assemblages associated with rock reef and non-rock reef were studied using specimens collected at three sites in Geomun Island waters of the Southern Sea, Korea, in February, May, August and October, 2006. Two survey methods for the study were followed: collection by a gill net, and video observation by scuba diving. The gill-net survey was conducted during the night, the scuba-diving observations were conducted during the day. From the gill-net survey, a total of 40 species, 380 inds. and 71,426.9 g was caught at the three sites. The dominant species was Trachurus japonicus; other species were Raja kenojei, Dasyatis akajei, Stephanolepis cirrhifer, Narke japonica, Pagrus major, Sebastes inermis, and Sphyraena pinguis. At the rock-reef site, a total of 26 species, 264 inds. and 46,776.7 g was caught by gill net, and the dominant species was T. japonicus. A total of 17 species, 45 inds., 10,535.1 g was caught at the flat-bottom 1 site, and 19 species, 71 inds. and 14,115.1 g were caught at the flat-bottom 2 site. The scuba-diving survey resulted in 13 species and 1,749 inds. observed at the three sites through the survey period. The main observed fishes were rock-dwelling species such as Chromis notatus, Microcanthus strigatus, S. cirrhifer, Ditrema temmincki, Evistias acutriostris, Girella punctata, Halichoeres poecilopterus, Hexagrammos agrammus, Prionurus scalprum, Sebastes inermis, and Semicossyphus reticulatus. Seven species and 1,739 inds. observed at the rock-reef site comprised 99.4% of the inds. of the three sites. Therefore, the fish community in Geomun Island waters included many rock-reef. species, but a few were migratory species like T. japonicus and Scomber japonicus. The abundance of fish at the rock-reef site was high in comparison with those at two non-rock reefs. The dominant species were very different between the day and the night, although rock-reef species comprised the main part of the fish community. We conclude that the high abundance of fish in Geomun Island waters is most closely related to physical structure, such as rock reefs, which is the main habitat of many fishes.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.275-287
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• 2013

The Japanese anchovy Engraulis japonicus is a widespread species in the western North Pacific and major fishery resource. To understand the spatio-temporal variation of anchovy prey items in the coastal waters of southern Korea, the stomach contents of anchovy and the structure of the zooplankton community were analysed at three sites (Jindo, Yeosu and Tong-yeong) from July 2011 to February 2012. The main prey items in Yeosu and Jindo were cyprid stage of barnacle (>35%) and copepod Calanus sinicus (>22%) in July, respectively, while, predominant ones in Tongyeong were small copepods, Paracalanus parvus s.l. (41%) and Corycaeus affinis (22%). During this period, the dominant zooplankton were cladoceran Evadne tergestina (39%) in Yeosu, small copepod, P. parvus s.l. (28%) in Jindo and cladoceran E. tergestina (14%) in Tongyeong. The dominant prey items were barnacle larvae and copepods in summer, phytoplankton and Pseudodiaptomus marinus in autumn and P. parvus s.l. and cold water copepod, Centropages abdominalis in winter. Anchovy prefer the prey item C. sinicus (3%) over E. tergestina (39%), which was a dominant species in the catching site in summer. P. marinus (0.5%) and C. abdominalis (0.9%) were preferred over P. parvus s.l. (30%, 21%) in autumn and winter, respectively. Prey items varied with area and season in the coastal waters of southern Korea. These results suggest that the prey selectivity of anchovy showed high flexibility and adaptability in the study waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.453-462
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• 1998

Macrobenthic community structure was studied at thirteen stations in Taebudo subtidal area, Korea, from July to October 1996. Triple macrobenthos samples were collected using a van Veen grab (0.1 $m^2$) at each station during the study period. A total of 209 species of macrobenthos was sampled with a mean density of 1,093 ind./$m^2$ and biomass of 134,86 g/$m^2$. Of these, there were 72 species of polychaetes ($34.5\%$), 69 crustaceans ($33.0\%$) and 49 molluscs ($23.4\%$). Polyalaetes were represented as a density-dominant faunal group with a mean density of 608 ind./$m^2$, comprising $55.6\%$ of the total benthic animals. It was followed by crustaceans with 307 ind./$m^2$($28.1\%$ of the total density), Echinoderms were represented as a biomass-dominant faunal group with a mean biomass of 54.21 g/$m^2$($40.2\%$ of total biomass). Total number of species and diversity were low in the inner part of the study area with high mud content and high in the offshore stations of mixed sediments. Major dominant species were three polychaetes, Heteromastus filifomis, Scoloplos armiger and Tharyx sp. whose mean densities were 70 ind./$m^2$, 67 ind./$m^2$, and 66 ind./$m^2$, respectively. Cluster analysis showed that the study area could be divided into five stational groups based on the faunal composition, that is, the innermost stations, coastal stations, transitional stations and two offshore station groups. The species diversity of these groups increased from the inner stational group toward the outer groups.