• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.823-833
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• 1997

To clarify the annual reproductive cycle of the banded catfish, Pseudobagrus fulvidraco (Richardson), the seasonal changes in histological aspect of gonad and liver were examined. The adult fish was raptured from the upper stream of Young-San river, Chunnam in each month from May 1992 to June 1993. Based on the annual changes in GSI (gonadosomatic index), HSI (hepatosomatic index), CF (condition factor) and histological aspects of the gonads, the annual reproductive cycle were classified into 5 periods as follows: 1) Growing phase (from April to early May): The value of GSI increased and the size of oocytes in perinucleolus stage in oocytes increased gradually. Spermatogonia were developed actively from the epithelial tissues of seminiferous tubules. 2) Maturing phase (from Hay to early June): GSI levels increased rapidly in both sex. Oocytes at various developmental stages were observed. Appearance of active spermatogenesis were observed. 3) Mature and spawning phase (from June to August): High values of GSI remained static and oocytes accumulated significant quantitis of yolk globules. 4) Degenerating phase (from September to November): GSI levels decreased and ovaries were filled mostly with oocytes at the perinucleolus stage. Hepatic cells accumulated significant amounts of lipid droplets. 5) Resting period (from December to March) : Low values of GSI were kept and the size of oocytes at the perinucleolus stage did not increase. Spermatogenesis was not observed.

• Journal of Environmental Science International
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• v.25 no.12
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• pp.1633-1641
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• 2016

Leptalina unicolor is a hesperiid butterfly with a restricted distribution in Korea, Japan, China, and Russia. Recently, the number of individuals is rapidly decreased in their natural habitat. This skipper has been classified as an endangered species in the 'Red Data Book', and according to an IUCN report, is under threat of extinction. Therefore, the conservation and restoration of this species both locally and globally are urgently needed. A population of L. unicolor was found in an unknown habitat in Jaeyaksan, Miryang, Gyeongsangnam-do, Korea in 2011, and these individuals were used in the present study. Here, the life cycle, characteristics of each instar larva and breeding information were determined by breeding L. unicolor in the laboratory from 2012 to 2015. The results indicated that L. unicolor occurs twice a year and over-winter as a fifth instar larva. A spring-form female individual laid $17.25{\pm}5.52eggs$, and summer form laid $29.00{\pm}5.86eggs$; it takes $53.79{\pm}0.73days$ for L. unicolor to develop from eggs to adults. After spawning, the eggs developed in $6.16{\pm}0.18days$, and larvae developed in $33.71{\pm}0.58days$; the pre-pupal stage to emergence required $14.22{\pm}0.31days$. Based on these results, we presented effective breeding information for the restoration and proliferation of the species. Several candidate plants species have been reported in the literature as a food source for L. unicolor, but we found that the preferred diet this butterfly was Miscanthus sinensis. The larvae could move easily when their preferred diet was planted in ${\geq}80%$ the cage floor area Year-round breeding was achieved by placing overwintering individuals in low temperatures in autumn. To our knowledge, this is the first study to the biology of L. unicolor in Korea, and the results of this study could be used as preliminary information for the conservation and restoration of this species in its natural habitat.

• The Korean Journal of Pesticide Science
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• v.16 no.2
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• pp.187-193
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• 2012

Acute toxicity, water resolvability and short term reproduction test on Japanese medaka (Oriyzias latipes) for evaluating alachlor susceptibility to endocrine system were studied. Alachlor is known for suspected endocrine distruptors. As the results of tests, $LC_{50}$ (Median lethal concentration) was determined as 2.36 (1.994~2.805) mg/L, and test water replaced at 7 day intervals as its water resolvability was less than 20% in 7 days. The short term reproduction tests on Japanese medaka (Oriyzias latipes) were performed with a solvent control group, a treated group (alachlor concentrations of 0.02, 0.04, 0.11, 0.27, 0.68 ppm) and a positive control group (17 ${\beta}$ estradiol, 0.01, 0.1, 0.5 ppb). The number of spawning and embryo rates were declined in a alachlor-dose dependent manner, and the number of unfertilized eggs rates were in contrast increased depending on the concentrations. Further study should be needed to confirm whether the adverse effects may be effected by the concentrations. Additionally, alachlor was evaluated as a non-vitellogenin by the result of a test of significance of the vitellogenin content test for determination of the effect of estrogen among the endocrine disruptors.

• Korean Journal of Environmental Biology
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• v.30 no.2
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• pp.128-135
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• 2012

The individual toxicity of lead (Pb) and zinc (Zn) has been investigated by using the sea urchin (Hemicentrotus pulcherrimus) germ cell and pluteus-larvae. The gametotoxic and embryotoxic effects of Pb and Zn on H. pulcherrimus were each investigated at 31, 63, 125, 250, 500 ppb and 16, 31, 63, 125, 250 ppb, respectively. Spawning was induced by 0.5 M KCl solution and the fertilization and normal embryogenesis rates test were performed for 10 min and 64 h after fertilization, respectively. In exposure to Pb, the fertilization rate was not significantly changed compared with control but normal embryogenesis rate was significantly decreased with concentration dependent manner. Fertilization and normal embryogenesis rates showed a significant decreased with concentration dependent manner in exposed to Zn. The normal embryogenesis rates were significantly inhibited in exposed to Pb ($EC_{50}$=45.13 ppb, 95% Cl=40.12~50.05 ppb) and Zn ($EC_{50}$=19.82 ppb, 95% Cl=18.26~21.31 ppb). In exposure to Pb and Zn, the NOEC of normal embryogenesis rate was <31.25 and <15.63 ppb, respectively. The LOEC showed each 31.25 and 15.63 ppb in exposed to Pb and Zn. These results suggest that the early embryo development of H. pulcherrimus is highly sensitive to heavy metals such as Pb and Zn, H. pulcherrimus can be used as a test organism for risk assessment in marine ecosystems.

• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.146-159
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• 2020

The objective of our study was to analyze the distribution and composition of fish species and their community characteristics in agricultural waterways in the six water systems-Mankyung River, Seomjin River, Namhae Region, Tamjin River, Yeongsan River, and Dongjin River-during 2017-2018. Little is known about the distributions and community characteristics of the aquatic biota of agricultural waterways in Korea, even if the water bodies have important roles as spawning areas or habitats for fish. In this study, we identified 3,633 fish individuals in the waterways, belonging to 53 species, eleven families, and six orders (dominant species: Tanakia koreensis, T. lanceolate) and 7,108 fish individuals in the main rivers, belonging to 57 species, fifteen families, and nine orders. Moreover, three endangered wildlife (designated by the Ministry of Environment, Korea)-T. somjinensis, Acheilognathus majusculus and Coreoperca kawamebari-were found in the waterways. By fish guild analysis, we found that many waterways had a lower proportion of sensitive species and a higher proportion of omnivore species than those of the main rivers, which indicates a feature of a disturbed environment. In addition, by grouping with environmental variables, we found the group of waterways with high substrate complexity had a higher diversity index (Shannon index) and a lower dominance index (Simpson index) than that of simple substrate complexity. Overall, our study represents the characteristics of fish habitats in agricultural waterways and suggests the need to manage them and study further.

• 한국해양학회지
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• v.4 no.1
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• pp.36-48
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• 1969

The larvae of Mytilus coruscus were grown at the room temperature of approximately 15.1C under several different sulture conditions, i.e., salinity, population of the larvae, density and kind of food organisms, etc. (1) The egg of Mytilus coruscus obtained in the laboratory measured about 73.0${\mu}$ in diameter. The embryos gradually developed into larvae up to 179.0${\mu}$ shell length with the shell height of 135.9${\mu}$ even in the absence of the algal food. Beyond this size, however, the growth of larvae was considerably retarded, indicating that the better growth could be expected if the food began to be fed four days after spawning. (2) The larvae began settling upon reaching 281.4${\mu}$ to 310.9${\mu}$ in shell length or 264.3${\mu}$ to 301.9${\mu}$ in shell height. When the shell length reaches 322.6${\mu}$ to 337.1${\mu}$, the shell height also reaches about the same, i.e., 321.5${\mu}$ to 346.2${\mu}$. (3) Daily rate of food consumption was determined by the size of the larvae and the species of the algal food. Regardless of the species of food given, the rage of food consumption remained almost the same until the larva reached the straight-hinge stage, and marked variations were found as the larvae grew larger. Daily rate of food consumption was shown as follow; Chaetoceros calcitrans : Y=2.99167e$\^$0.000018243x$\^$2// Cyclotella nana : Y=3.00324e$\^$0.000015481x$\^$2// Monochrysis lutheri : Y=3.000056e$\^$0.000014485$\^$2// (4) Suitable amount of the food to be given was about five times of the consumed food by Mytilus coruscus. (5) When the numbers of the larvae was higher than ten per milliliter, the growth was significantly retarded. (6) Monochrysis lutheri and Cyclotella nana were much better than Chaetoceros calcitrans as the food of Mytilus coruscus, and even the same food organism showed some difference with the age of the organism. (7) Sea water of higher salinity showed the better result in the growth of the larvae and the water with the specific gravity of 1.020 or below was dangerous for the larvae. (8) The mean growth of the larvae of Mytilus coruscus under lavorable condition was shown as follows: shell length 121.8${\mu}$ to 179.0${\mu}$ : Y=119.18+7.42X 196.7${\mu}$ to 322.6${\mu}$ : Y=203.144+7.687X 322.6${\mu}$ to 985.1${\mu}$ : Y=302.5978+11.8356X shell height 86.3${\mu}$ to 135.9${\mu}$ : Y=86.22+6.40X 158.1${\mu}$ to 321.5${\mu}$ : Y=162.998+10.027X 321.5${\mu}$ to 1,215.4${\mu}$ : Y=309.3701+16.258X Relationships between the shell length and shell height were shown as follows: shell length 121.8${\mu}$ to 179.0 : Y=0.83726X-15.79165 196.7${\mu}$ to 322.6 : Y=1.29909X-100.58610 322.6${\mu}$ to 985.1${\mu}$ : Y=1.3536X-101.6806

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.3
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• pp.109-124
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• 2018

In order to find the optimum culture condition for marine free-living nematoda in the laboratory, various agar media were developed and experiments were carried on nematodes. Nematodes have collected from the bottom of the sandy sediments' surface layer (about 5cm sediment) of Taean Mallipo beach's intertidal zone. Especially, with regard to agar medium, Killian medium was transformed slightly, density of agar had made a difference and this agar medium(height 2.0 mm on diameter 60 mm Petri dish) was divided. It was mixed with 5 different species of microorganism as nematodes' live food and added each culture medium. Five individuals of Enoplolaimus sp. on each culture medium were grown in a culture medium which was set on $20^{\circ}C$ and light blocked. Moreover, as a result of the optimum culture condition, 1.0% density of agar showed the highest survival rates (the average time of survival is 246.8 hours). On the other hand, the 0.4% density of agar adding Killian medium, bacto peptone and beef extract showed the lowest survival rates, which indicates the average time of survival is 27.6 hours. About Bathylaimus sp., on Killian medium's 1.0% density of agar(no feeding amount) showed the highest survival rates, which connects that the hatching rate 94.7% after 99.5 hours and it laid 7 eggs averagely on the spawning amount and the hatching rate experiment.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.282-294
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• 2000

The reproductive ecology and the early life history of Macropodus chinensis were investigated in aquarium. Mature male made the bubble nest and spawned with wrapping the female and reverse posture. The parental male protected the offspring until the larvae depart the bubble nest. Egg productivity and egg hatching rate were the highest at water temperature in $28^{\circ}C$ and $26^{\circ}C$ respectivity than any other artificial temperature. The eggs were buoyant, globular and 0.95${\sim}$1.05 mm in diameter. Cleavage was progressed at intervals of 15 minutes. Eggs hatched in 42${\sim}$44hours after fertilization and the newly hatched larvae were 3.0${\sim}$3.2 mm in total length. The lawae were 4.5${\sim}$5.4 mm in 4${\sim}$5 days after hatching and fed on the food with dispersion from the nest. In 40${\sim}$45 days after hatching, all fin rays completely developed, and juveniles reached 18.2${\sim}$23.5 mm in total length. In 90${\sim}$110 days after hatching, body from of young fishes were similar to adult with 37.4${\sim}$48.2 mm and represented secondary sexual characters longer than 45.0 mm in total length, and about 120 days, fishes began spawning(water temperature for ontogenesis: $26.0{\pm} 1^{\circ}C$).

• Journal of Wetlands Research
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• v.18 no.3
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• pp.313-323
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• 2016

Water temperature affects physical and biological processes in ecologies on river system and is important conditions for growth rate and spawning of fish species. The objective of this study is to compare models for water temperature during the summer season for the Fourchue River (St-Alexandre-de-Kamouraska, Quebec, Canada). For this, three different models, which are CEQUEAU, Auto-regressive Moving Average with eXogenous input and Nonlinear Autoregressive with eXogenous input, were applied and compared. Also, future water temperature in the Fourchue river were simulated and analyzed its result based on the CMIP5 climate models, RCP 2.6, 4.5, 8.5 climate change scenarios. As the result of the study, the water temperature in the Fourchue river are actually changed and median water temperature will increase $0.2{\sim}0.7^{\circ}C$ in June and could decrease by $0.2{\sim}1.1^{\circ}C$ in September. Also, the UILT ($24.9^{\circ}C$) for brook trout are also likely to occurred for several days.

• Journal of Mushroom
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• v.11 no.4
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• pp.244-248
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• 2013

"Hwaseong 5ho" was developed by the method of Di-mon mating between monokaryotic strains derived from "Hwaseong 1ho" and dikaryotic strain "PSC109". The color of pileus was dark grayish brown, the shape of pileus was convex or infundibuliform. The length of stipe was longer and the thickness of stipe was some thinner than Suhan 1ho. Material properties of stipe of "Hwaseong 5ho" was higher in strength, hardness, chewingness and brittleness than Suhan 1ho, but similar in elasticity and cohesion. RAPD using URP-primer showed not the same between two strains. Days of primordia formation period were 22-27 days after spawning, that was a little later than Suhan 1ho. In the trial using culture box containing composted cotton waste, yield index of 'Hwaseong 5ho' was 16.6% higher than Suhan 1ho. The farm field trial were showed stable productivity in each different growing conditions.