• Journal of Environmental Health Sciences
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• v.23 no.2
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• pp.89-97
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• 1997

Most of urban streams in Korea have been changed channel forms and suffered from direct inflow of domestic sewage, etc. Therefore, maintenance of structure and function of those ecosystem are hard. The present study was carried out to examine the life survival maintenance ability of the stream by community analysis of aquatic animals in typical urban stream (Jungrang stream) in Seoul. The aquatic animals were composed of 31 species, 18 families, 8 orders, 5 classes in 4 phyla. Seasonal species number showed big fluctuation between 8 species in Winter and 24 species in Autumn. Major dominant species in Jungrang stream were Tubificidae sp.1, Chironomidae sp.1, Chironomidae sp.2 and Physa acuta, and above endurance species for water pollution occupied very high dominance indices. But, Cercion hieroglyphicum, Ischnura asiatica, Rantra chinensis, Herochares striatus, Agabus japonicus in benthic macroinvertebrates of a few individuals are appeared. Also, fry of Carassius auratus and Silurus asotus in fish are occurred. Therefore, we can be inferred on posibility of growth and spawning of above species in the stream. Jungrang stream has a small quantity of natural riffle areas, ponds and watergrass areas by channel form of water course. Aquatic animals in Jungrang stream has been suffered by reduction of self-purification reaction ability and have mass production of attached algae on the stream bed. For analysis of fluctuation of life survival maintenance ability in Jungrang stream, long-term survey is needed.

• Journal of Aquaculture
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• v.9 no.1
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• pp.65-71
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• 1996

To estimate the variation of food organisms on the corrugated PVC sheets, we analysed the chlorophyll a and. pheopigments of the benthic microalgae on the sheets from the oyster culture ponds. We estimated the standing crops as the amounts of chlorophyll a, and the physiological state of cells as the pheopigments level in the benthic microalgae. The amount of chlorophyll a was increased by immersion time in winter but the peak was observed every two weeks in summer, while the ratio of pheopigments was highest in summer but the low level was observed in spring and autumn. These seasonal variation were well coincided with the natural spawning season and the good microalgae nutritional valance.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.5
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• pp.761-772
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• 2020

In order to study about species composition and community structure of fish in the coastal water off Boryeong were investigated from January 2018 to December 2019. A total of 10,863 individuals of 87 species of 44 families were collected. The dominant species were Liparis tanakai accounted for 19.8 percent of the total with Amblychaeturichthys hexanema and Collichthys niveatus accounted for 12.4 percent and 11.0 percent of the total number. A cluster analysis based on the Bray-Curtis similarity revealed that the fish community divided into two groups, According to season. The fish species that appeared summer and autumn were mainly migratory, while the fish species that appeared in spring and winter were mainly resident species. Fish caught by stow net had a high percentage of immature fish. It presented that coastal water off Boryeong is located an important spawning and nursery for fisheries resource.

• Korean journal of applied entomology
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• v.55 no.3
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• pp.235-243
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• 2016

The winter cherry bug, Acanthocoris sordidus (Thunberg), is an insect pest hat damages plants from Solanaceae and Convolvulaceae. The developmental period from egg to adult averages 76 days at $25^{\circ}C$. Adult egg-laying occurred irregularly via spawning, averaging 195 (up to 468) eggs per individual on the abaxial leaf surface of the host plant. Results of linear regression indicated that the lower developmental threshold temperature was $13.9^{\circ}C$ and the effective accumulated temperature was 526.3 DD. Data from a pepper field in 2015 indicated that overwintering adults first appeared during late June (daily average temperature = $25.7^{\circ}C$), reaching maximum density by early September. A choice test examining colonization preferences using a net cage and a Y-tube olfactometer revealed that females gravitated toward conspecifics (other females, males, or both), whereas males moved toward empty areas. Finally, we found that communal breeding results in a longer developmental period and higher eclosion rates than solitary breeding. Developmental periods and eclosion rates were also for colonies in a large space than for those in a small space. This outcome suggests that colonization effects on insect development are stronger in a smaller area.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.266-280
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• 1989

Gonadal maturation of the Korean pomfrets, Pampus echinogaster (Basilewsky) and Pampus argenteus (Euphrasen) were histologically investigated based on the samples captured in the East China Sea from January 1987 to December 1988. Gonadosomatic index (GSI) of P. echinogaster began to increase from March, and reached maximum between May and July. It began to decrease from July and reached mini-mum between August and February. P. argenteus had a similar cycle, however, P. argenteus has higher values in April than P. echinogaster. Hepatosomatic index (HSI) were positively related to GSI. HIS of P. echinogaster and P. argenteus reached maximum in $April\~July$ and $April\~August$, respectively, Fatness coefficient of two Pampus species were low in the summer, and high in the winter. Ovary is of saccular structure, and testis is of lobular structure. From February, the early oocyte (ca. $100\mu$ in diameter grows) rapidly at the germinal epithelium of ovarian sacs. From March to April the oocytes grew up to cu $400\~500\mu$ in diameter. At this stage, the yolk globules are accumulated rapidly in the cytoplasmic layer. From May, the oocytes roached ca. $650\~850\mu$ in diameter, and they are spawned in $May\~July$. After spawning the residual follicles and remained ripe eggs degenerate. From February, spermatogonia grows into spermatocyte on the epithelium of the testicular lobuli. From May, spermatozoa appeared and spawning occurs. After spawning, the epithelium is thickened and the remained spermatozoa degenerate. Annual reproductive cycle of two Pampus species could be divided into four successive stages: Growing stage ($March\~April$), Mature stage ($April\~May$), Ripe and spent stage ($June\~July$) and Recovery and resting stage ($August\~January$). Absolute fecundity of P. echinogaster was $9,441\~135,294$, and that of P. argenteus was $50,678\~221,894$. Absolute fecundity of two Pampus species were positively related to body length and total weight. Relative fecundity was positively related to body length, while it was reversely related to total weight. The increasing rate of absolute fecundity of P. echinogaster was lower than P. argenteus. In P. echinogaster half of female and male reached first maturity at body length of $15.0\~$17.9cm and $12.0\~14.9cm$, respectively. All of females and males reached first maturity at body length of $18.0\~20.9cm$ and $21.0\~23.9cm, respectively. In P. argenteus all of females and males reached first maturity at body length of 18.6cm and 16.7cm$, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.68-80
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• 1984

Garolim Bay is not only important fishing ground but also expected area for the tidal power plant. The construction and operation of tidal power plant will make change the ecosystem of this bay. Therefore, the actual fisheries stocks should be precisely understood for the effect estimation and overall utilization of the bay after the construction of the tidal power plant. During the study period from January through December in 1981, forty-six adult fishes species, 3 species of fish egg and 25 fishes larvae species have occurred in the bay. Considering the result on monthly distribution of eggs and larvae, the inner area of the bay seems to be important as nursing ground of larvae spawned at the outside bay in winter, e. g., Ammodytes personatus, and Enedrias sp. This inner bay is also major spawning ground for many species spawning in spring and summer, e. g., Gobiidae, Konosirus punctatus, Engraulis japonica, etc. Taking into consideration the annual mean production for three years($1978{\sim}1980$), there are two major fishing seasons. The one is in May-June for Enedrias larvae stock, and the another in October-November for big eyed herring stock. For the mariculture stocks, short necked clam, oyster and laver are important species. After construction of the tidal power plant, the migratory species, i. e., larvae of Enedrias and Ammodytes personatus, Mugil cephalus, Konosirus punctatus, etc. will be directly damaged by the interuption of migration route. On the otter hand, the change of physico-chemical factors of seawater will also affect the ecosystem of the bay. Consequently, for the overall utilization of the bay after construction, the actual ecosystem including the fisheries stocks, must bs precisely revealed, and the mechanical designs, e. g., sluice position and its demension, should be also considered with these biological characters of the bay.

• Korean Journal of Ichthyology
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• v.7 no.1
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• pp.25-32
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• 1995

The larval fish, which had been previously identified or classified as Enedrias (Pholis) nebulosus, Enedrias spp., Pholis taczanowskii, and unidentified species belonging to Protosalanginae, were revealed as that of a gunnel, Enedrias fangi. This species has been known as a cold water species mainly caught in the Yellow Sea. Larval E. fangi showed peak abundances in the coastal waters off Chonlla Province in March, Chungnam Province in April, and Kyunggi Province in May and June. The primary spawning season of E. fangi seemed to be winter (November to January), and the eggs hatched after 60 days from spawning. The average growth rate of larval fish was about 0.33mm/day. The larval fish of 40mm in body length began to move to the bottom, and stayed in the bottom cold water mass when their body length was greater than 60-70mm. The average annual catches of larval E. fangi from 1985 to 1991 were 5,000M/T in the Yellow Sea, which were more than 99 % of the total gunnel catches around Korean waters. The peak season of catches was from March or April to July in Chungnam Province, and from May to July in Kyunggi Province.

• Korean Journal of Ichthyology
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• v.7 no.1
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• pp.56-63
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• 1995

Ecological study of the Cynoglossus joyneri was conducted based on the specimens from the western coast of Korea from 1992 to 1994. Ecological characteristics of this species such as gonadal development, occurrence of larvae, stomach contents, and environmental conditions were investigated. Few larvae of Cynoglossus joyneri occurred in Kunsan coast. This coast is influenced by the freshwater input of the Mangyong and Kum River, especially during the summer. Therefore, the larvae of C. joyneri were considered to be spawned and grown during their early life stage in the high saline water in outer bay. Spawning occur from June to September, having the peak spawning period from July to August. Biological minimum size of matured fishes containing mature oocytes is about 143.5mm in total length, which requires about 20 months after hatching. The ranges of total length by age are as follows : 0-ring group(floating stage), 30~70mm ; 1-ring group, 49.0~133.0mm 2-ring group, 128.6~167.0mm ; 3-ring group, 169.0~202.0mm ; 4-ring group, 200.7~240.0mm. The major food items of young fish under 8cm were copepods and invertebrate larvae, and those of adult fishes were annelids(polychaets) in winter, and bivalves and shrimps in summer and autumn. Therefore, it can be assumed that the population of C. joyneri could be reduced due to the decrease of food organisms caused by the continuous reclamation activities in the inner bays of the west coast of Korea.

• Korean Journal of Ichthyology
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• v.7 no.1
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• pp.43-55
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• 1995

Based on the reproductive cycle of Rhodeus uyekii, the reproductive control mechanism was examined under the several combinations of photoperiod and temperature regimes at different phases of their reproductive cycle. In early spring, the gonads developed rapidly under the warm temperature condition(above $8^{\circ}C$), regardless of the photoperiod. In late spring or early summer, gonads intensely regressed under the high temperature condition(above $24^{\circ}C$), regardless of the photoperiod. Thus, it is concluded that the spawning period of R. uyekii is initiated by the rising of water temperature in spring and is terminated by the high temperature in early summer. In autumn, the gonadal recrudescence occurs under the conditions of artificial long daylength with warm temperature(15L/9D, $12^{\circ}C{\sim}20^{\circ}C$), whereas the gonads remain in the existing condition under the short daylength. Therefore, in autumn the gonadal recrudescence is prevented by the short daylength although the temperature is still in favorable condition. In bitterling, the responsiveness of the gonads to photoperiod varies clearly with seasons, which was declined during the winter but increased during the autumn. The critical photoperiod for maturation ranges 12~13 hours of light per day. The results indicate that the proper ranges of temperature and photoperiod for gonadal maturation of this species are from $8^{\circ}C$ to $8^{\circ}C$ and from 13L to 15L, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.83-91
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• 1986

The activity of the liver cells of greenling, Agrammus agrammus were histologically investigated under photo-and electron microscopy, and studied by comparing seasonal changes of hepatosomatic index (HSI). The materials were monthly collected at the costal area of Tongbaeksom, Pusan, Korea, from September 1983 to August 1984. The annual variations of HSI of male were not distinct, but those of HSI in female began to increase in autumn, and reached the maximum in winter when the ovary was getting mature. During the period of yolk accumulation in the oocytes, the female liver and its hepatic cells were seen to large and nuclei and nucleoli were hypertrophic also. At this time the amounts of glycogen and lipid in the cells gradually decreased, while basophilic substance (RNA) increased. And well-developed granular endoplasmic reticula binding ribosomes were supposed to play the leading role in protein synthesis and deposition for vitellogenin in the cystoplasm. Just prior to spawning, glycogen and lipid droplets were decreased, but basophilic substances(RNA) were found in a high concentration especially at the peripheral region of the liver cells of females. In the liver cells of males, were hardly altered by gonadal maturation, basophilic substances gradually increased, glycogen particles and lipid droplets were still observed in large quantities. After spawning, basophilic subtances decreased in the liver cells of female and male.