• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.167-177
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• 2006

Both fish community and water quality in Lake Doam were investigated from September 2004 to August 2005. The turbidity of Lake Doam located in the upper region of the Songchun River in the South River system, Korea was high whole year due to the effects of distributed non point source pollutions in the watersheds. During the experimental periods, mean concentration of chlorophyll-a in epilimnetic layer (0 ${\sim}$ 5 m) was 18.5 ${\mu}g\;L^{-1}$ and transparency ranged from 0.3 m to 2.4 m. Average TP and TN concentrations were 111 ${\mu}g\;L^{-1}$ and 4.1 $mg\;L^{-1}$, respectively. Lake was classified as eutrophic state based on the nutrient concentrations suggested by U.S.EPA (1976). Total number of fish collected in Lake Doam was 9,600 individuals in 26 species of 6 family. Both dominant and subdominant species in the lake were P. herzi (34.9%) and Z. platypus (22.5%), respectively. Occurrence of water column species was high at upper region of the lake, whereas benthic type of species highly ,appeared in downstream area. The different fish assemblage between upper and lower area would be considered as the difference of bottom substrate and concentrations of suspended solids. In addition high appearance of Comat type of fish that is hybrid between gold fish (C, auratus) and C. auratus was found in the lake. It was unclear the reasons that high proportion of mutant species appeared in the lake. More researches are required in this area in future.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.172-177
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• 2011

The study sought to determine the efficient management of Korean aucha perch by estimating the potential yield (PY), which means the maximum sustainable yield (MSY) based on the optimal stock, in the mid-upper region of the Seomjin River watershed from August 2008 to April 2009. The stock assessment was conducted by the swept area method and PY was estimated by a modified fisheries management system based on the allowable biological catch. Also, the yield-per-recruit analysis (Beverton and Holt, 1957) was used to review the efficient management of resource, Coreoperca herzi. The age at first capture ($t_c$) was 1.464 age and converted body length was 7.8 cm. Concerning current fishing intensities, the instantaneous coefficient of fishing mortality (F) was estimated to be 0.061 $year^{-1}$; yield-per-recruit analysis estimated the current yield per recruit as 4.124 g with F and $t_c$. The fishing mortality of Allowable Biological Catch ($F_{ABC}$) based on the current $t_c$ and F was estimated to be 0.401 $year^{-1}$, therefore, the optimum fishing intensities could be achieved at the higher fishing intensity for Coreoperca herzi. The calculated annual stock of Coreoperca herzi was 3,048 kg, the potential yield was estimated to be 861 kg with $t_c$ and $F_{ABC}$ at the fixed current level. Using yield-per-recruit analysis, if F and $t_c$ were set at 0.643 $year^{-1}$ and 3 age, respectively, the yield per recruit would be predicted to increase 3.4-fold, from 4.12 g to 13.84 g.

• Korean Journal of Ecology and Environment
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• v.43 no.2
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• pp.288-297
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• 2010

This study was to evaluate the ecological stream health through the Multimetric Fish Assessment Index (MFAI) along with fish fauna analysis based on the tolerance and trophic guilds at Miho stream in 2008 and 2009. Also, we analysed total mercury concentration in fish tissues to examine heavy metal contamination. Total sampled fish were 40 species and 2,557 individuals and Zacco platypus was the most dominant with 35% relative abundance. It was sampled with 11.4% RA for Korean endemic species (10 species 291 individuals) less than average RA 39.3% for the Geum river watersheds. According to the tolarance guild analysis, tolerant species was more dominant with 58.9% RA (15 species, 1,507 individuals) than sensitive species with 6.6% RA. Trophic guild analysis also suggested that omnivores were more dominant (60.5% RA) than insectivores (31.5% RA). Riffle-benthic species was also sampled with 7.7% RA. Ecological stream health based on the MFAI were averaged 25.3 (n=3) with fair-poor condition in 2008 and also 26.3 (n=3) with fair condition in 2009, just slightly increased than 2008. Qualitative habitat evaluation index was averaged 134 (n=3) with fair condition but most of sites had sediment accumulation that reflected substrate degradations proceeding. From the result of total mercury accumulation in fish tissues, kidney and liver tissues showed the highest but the lowest for gill tissues. Overall mercury concentration were not exceed the national standards by Korean Federation of Drug and Administration (KFDA). Consequently, our result could correspond with the characteristics of Miho stream where point sources such industrial complexes and wastewater treatment plant widely distributed around the stream along the gradient of up and downstream.

• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.82-90
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• 2010

The ecological characteristics of the Korean Aucha perch, Coreoperca herzi, were determined in order to estimate stock of the mid-upper system of the Seomjin River. The age was determined by counting the otolith annuli. The oldest fish observed in this study was 5 years old. Relationships between body length (BL) and body weight (BW) were $BW=0.0195BL^{3.08}$ ($R^2=0.966$) (p<0.01). Relationships between the otolith radius (R) and body length (BL) were BL=3.882R+1.66 ($R^2=0.944$). The von Bertalanffy growth parameters estimated from a non-linear regression method were $L_{\infty}=19.68\;cm$, $W_{\infty}=188.64\;g$, $K=0.17\;year^{-1}$ and $t_0=-1.46$ year. Therefore, growth in length of the fish was expressed by the von Bertalanffy's growth equation as $L_t=19.68$ ($1-e^{-0.17(t+1.46)}$) ($R^2=0.997$). The annual survival rate (S) was estimated to be $0.666\;year^{-1}$. The instantaneous coefficient of natural mortality (M) of estimated from the Zhang and Megrey method was $0.346\;year^{-1}$, and instantaneous coefficient of fishing mortality (F) was calculated $0.061\;year^{-1}$. From the estimates of survival rate (S), the instantaneous coefficient of total mortality(Z) was estimated to be $0.407\;year^{-1}$.

• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.136-141
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• 2010

In situ experiments of Nutrient Enrichment Bioassays (NEBs) were conducted in the field along with in the laboratory to determine which nutrient limited phytoplankton growth as a indicator of primary productivity. For the NEBs, the water was sampled using a polyethylene-lined container and dispensed into 6 L water tank in the laboratory. The control (C, no nutrient spike) and six treatments of phosphorus (P), 2-fold phosphorus (2P), 4-fold phosphorus (4P), nitrate nitrogen ($NO_3$-N), 2-fold nitrate nitrogen ($2NO_3$-N), and phosphorus and nitrate nitrogen (P+$NO_3$-N) were set up in the lacustrine zone near the dam site, Daechung Reservoir in September, 2009 and analyzed the diel changes of total nitrogen (TN), total phosphorus (TP), and chlorophyll-$\alpha$ (Chl-$\alpha$) in the cubitainers. The short-term NEBs showed that algal response in the treatments spiked phosphorus (P, 2P, and 4P) were significantly (p < 0.05) greater than the response in the control (C), and nitrogen-spike. Also, the response in 4P-treatment was greater than those in the P- and 2P-treatments. In contrast, there was no significant differences (p > 0.20) between the $NO_3$-N and $2NO_3$-N treatment. The outcomes of the NEBs suggest that phosphorus limited the phytoplankton growth and nitrogen was not limited in this system. Furthermore, in the N + P treatments, the response was minimum, compared to all other treatments and the control, indicating that even if the system is evidently P-limited system, when added the nitrogen, the response showed the inhibition. Also, > 95% of observed long-term TN:TP ratios in the ambient water showed > 17, which is the criteria of P-limitation, supporting the P-limitation in the system. Overall, these results suggest that phytoplankton biomass near the dam is a direct linear function of P-loading near the watershed, if the phosphorus pool is mainly dissolved fraction.

• Journal of Aquaculture
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• v.11 no.4
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• pp.573-580
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• 1998

Red spotted grouper, Epinephelus akaara is distributed in the south and west coasts of Korea. The natural stocks of the fish are decreasing sharply year by uear because of reckless overfishing. This research was carried out to understand general informations on maturation, sex composition and sex-reversals of the fish. Annual fishing uields of red spotted grouper in the castal area of Byonsan Peninsular of Kora decreased over 10% from 1992 to 1994. The main fishing season was from May to July with fishing gear of Hand-lines. Gonadosomatic index (GSI) and condition factor were highest on early and late July, respectively, thus main spawning reriod was assumed from late July to early August. The relationship between total length (X) and body weight (Y) for wild adults was represented as a regression, Y=$0.0169X^{2.9705}$, ($r^2$=0.96). Frequency of sex of wild red spotted gouper showed that the number of female below 38cm in total length was more than that of male, and hermaphrodite mainly occurred from 28cm to 32cm in total length the frequency of male and female were almost same. Also hermaphrodite occurred mainly between 25~29cm. Sex reversal ration of the adults reared in a tank for a year with different sexual compositions revealted that the frequency of female reversed from male was more than that of male reversed from female at 1:1 and 1:2 stocking densities of female and male, respectively. Also, about 20% of female was reversed to male when all females were reared. And the size of the fish reversed to male was larger than that of non-reversed female.

• Journal of Aquaculture
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• v.6 no.4
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• pp.255-271
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• 1993

For the development of seedling production techniques of the freshwater crab Eriocheir japonicus, the effects of salinity and temperature on the growth of larvae of the crab were studied. Embryos hatched out as zoea larvae were measured 0.421 mm in average carapace length. Five zoea stages needed 16-26 days for metamorphosis from zoea to megalopa at $22^{\circ}C$ and $24.5\%o$. The average carapace length of the 5th zoea was 1.16 mm and that of the megalopa larvae was 1.89 mm. Each zoea stage could be identified based on both the number of plumosed seatae on the exopodite of maxilliped, and the number of spines on the posteroinner margin of tel son and also based on the rudimentary pleopods appearence. Zoea larvae fed rotifers and Artemia nauplii were healthy and metamorphosing rate from zoea to megalopa was $80\~90\%\;at\;22\~26^{\circ}C\;and\;17.5\~31.5\%o$. The relationship between larval period (Y in days) and water temperature $(X\;in\;^{\circ}C)$ is expressed as Log Y = 3.8604-1.91735 LogX. Water temperature and salinity ranges for better survival and metamorphosis of the larvae were $ 22^{\circ}C\~26^{\circ}C\;(optimum\;at\; 26^{\circ}C)\;and\;17.5\%o\~31.5\%o\;(optimum\;at\;24.5\%)$, respectively. The duration of larval stages tend to longer as salinity levels deviated from optimum particulaly at lower end. All zoea larvae did not survive in freshwater.

• Applied Microscopy
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• v.34 no.1
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• pp.31-42
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• 2004

Acute respiratory distress syndrome (ARDS) is a kind of acute lung injury characterized by inflammatory disruption of alveolar-capillary barrier and notorious for its high mortality. Neutrophils cause cell damage through the production of free radicals, inflammatory mediators, and proteases in ARDS. $PLA_2$ might serve a primary regulatory role in the activation of neutrophils. This present study was performed to elucidate the effect of rutin known as $PLA_2$ inhibitor on ARDS induced by endotoxin. Endotoxin had increased lung myeloperoxidase (MPO) activity, BAL (bronchoalveolar lavage) protein content, numbers of neutrophils in BALF (bronchoalveolar lavage fluid) compared with those of control rat (p<0.001). In addition, histological evidence of lung injury was correlated with neutrophil influx into alveolar space and cerrous perhydroxide granules were found in lining of endothelial cell, alveolar type I, II cells. In contrast, pretreated group of rutin had significantly decreased all of the parameters (p<0.001). These data suggest that inhibition of $PLA_2$ is one step approach that block the process of ARDS. Accordingly, we conclude that rutin can be used as the prophylactic agent for ARDS on the bases of these experimental results.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.203-214
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• 2018

Ballast water treated by sodium dichloroisocyanurate (NaDCC) injection method in ballast water management system (BWMS) contains reactive bromine, chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on the marine environment. WET testing was carried out for eight marine and fresh water organisms, i.e. diatom, Skeletonema costatum, Navicula pelliculosa, green algae, Dunaliella tertiolecta, Pseudokirchneriella subcapitata, rotifer, Brachionus plicatilis, Brachionus calyciflorus and fish, Cyprinodon variegatus, Pimephales promelas. The WET test revealed that diatom and green algae were the only organisms that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50 % (EC50) values of 25.0 %, 50.0 % and over 100.0 %, respectively, in seawater conditions. In contrast, rotifer and fish showed no toxicities to the effluent in the all salinity conditions. Meanwhile, chemical analysis revealed that the BWMS effluent contained total of 25 DBPs such as bromate, isocyanuric acid, formaldehyde, chloropicrin, trihalomethanes (THMs), halogenated acetonitriles (HANs) and halogenated acetic acids (HAAs). Based on ERA, the 25 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. The ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the all DBPs did not exceed 1.0 for general harbour environments, but isocyanuric acid, tribromomethane, chloropicrin and monochloroacetic acid exceed 1.0 for near ship environments. However, when NOEC (25.0%) of the WET test results where actual effluent was applied, it was concluded that the NaDCC injection method did not have unacceptable ecological risks to the general harbor including near ship environments.

• Korean Journal of Weed Science
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• v.17 no.4
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• pp.439-444
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• 1997

The causes of late establishment of barnyardgrass and their density effect on rice yield loss were examined in 1996 and 1977. Herbicide application on 5 to 15DAT(Days after transplanting) increased from 6% to 52.5%, 1988 to 1992, and their ingredient amount for barnyardgrass control decreased to 41.7-87.5% in Korea. Most late establishment of barnyardgrass in machine transplanted rice field were not late germinated but revived ones. The number of late established barnyardgrass were 0.5, 2.0 and 13.3/$m^2$, on direct seeded at May 10, and machine transplanted May 23 and June 9, individually. Relation on rice yield and the number of barnyardgrass at machine transplanted field showed highly significant equation, as y=543.3 4.7x, r=0.9039 in 1996 and y=515.8 10.4x+0.066$x^2$, $R^2$=0.9532 in 1997. Theoritical yield loss by regress equation showed 2% per one plant of barnyardgrass per $m^2$ and 5, 10, 20, 50, and 80 plants of barnyardgrass decreased rice to 10, 19, 35, 69 and 79%, individually.