• Journal of Korean Society of Coastal and Ocean Engineers
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• 제23권5호
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• pp.358-368
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• 2011

Responses of plankton populations to nutrient enrichment in mesocosm experiments in Shihwa lake were simulated using FVCOM. Dissoloved oxygen module was added to the FVCOM to simulate impacts of its decreased levels. The ecological model included the major components of the pelagic ecosystem including nutrients, phytoplankton (pico-, nano-, micro-), zooplankton (two groups of protozoa, mesozooplankton), particulate organic matter, dissolved organic matter and bacteria, and was calibrated using trophodynamic data collected from Gyeonggi Bay and Shihwa Lake. The model was able to reproduce major responses of plankton populations to nutrient enrichment, including phytoplankton of different size groups, change of dominance of protozoa from < 20 ${\mu}m$ oligotrichs to scuticociliates, and reponses to bacteria and low levels of dissolved oxygen in water column of the mesocosms.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제22권5호
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• pp.344-351
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• 2010

Uncertainty analysis on the net flow discharge (NFD) influencing the long-term material transport and the simulation results of the salinity and COD concentration distribution using the MIKE21 diffusion model in Gyeonggi bay and Han-River estuary is carried out. The NFD flowing the Gyodongdo - Seokmodo channel via the North channel of Ganghwado is estimated about 97% of the total NFD and the NFD of the Yeomha channel is estimated as only $2.5{\sim}3.0%$. On the other hand, the uncertainty defined as the difference by the different time-scale data input is analysed by the comparison of the model simulation result of the salinity and COD concentration distribution. One is computed based on the daily river flow data, and the other is computed based on the monthlymean river flow data. The results show that the salinity and COD concentration differences are about -10~20 psu and ${\pm}1.0\;mg/L$ during the summer season having a high flow discharge in Yeomha channel, respectively. The difference is clearly negligible in the open sea area.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제31권6호
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• pp.882-888
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• 1998

This study was designed as a part of efforts to investigate the biochemical pollutant markers for diagnosis of marine pollutions by changes in lipid components of the flounder (Paralichthys olivaceus) in the South Sea of Korea, Hemoglobin levels in serum of cultured flounders in the South Sea were lower ($4\~17\%$) than those of wild flounder in Pohang as a control group. Triglyceride (TG), Total and low density lipoprotein (LDL)-cholesterol contents in serum of cultured flounders in the South Sea were $12\~25\%,\;9\~19\%$ and $17\~25\%$ respectively which are higher than those of wild flounder in Pohang. Atherogenic index (AI) and T-Chol/PL ratios in serum of cultured flounders in the South Sea were significantly higher($26\~43\%$ and $17\~26\%$ respectively) than those of wild flounder in Pohang. These results suggest that near-coastal water as well as neritic water of the South Sea might be affected by pollutant input as well as the Yellow Sea of Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제31권6호
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• pp.842-851
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• 1998

Development and growth of Acartia steueri from Ilkwang Bay, southeastern coast of Korea, were determined under various temperatures and food condition (Isochrysis galbana and Dunaliella salina) in the laboratory. Relationship between egg hatching time ($D_E$, day) and temperature (T, $^{\circ}C$) was $D_E=744(T+3.5)^{-1.97}$. Mean hatching success was $88.4\%$ in temperature range of $8.4\~26.2^{\circ}C$. This suggests that A. steueri may be adapted to the temperature ranges in temperate regions. Post-embryonic development pattern was equiproportional rather than isochronal, with longer stage duration of copepodites than that of the nauplii. Stage duration of NI was the shortest of all developmental stages, while the duration of NII was the longest in duration of the other nauplii. Male was morphologically distinguished from female in CIV stage, and male was developed faster than female. Median development time at a given temperature was calculated from the Belehradek equation by proper multiplication of proportional constant for embryonic development. Body carbon weight at $19.1^{\circ}C$ was increased exponentially with time. Mean specific growth rate of nauplii (0.200 $d^{-1}$), except for NI stage, was not significantly different from that of copepodites (0.190 $d^{-1}$), with the lowest rate in NVI stage (0.107 $d^{-1}$), probably due to energy consumption for metamorphosis rather than somatic growth. The results suggest that although the development pattern determined in this study was not identical with Uye's result for A. steueri (e.g. Uye, 1980b), median development time may be applicable to calculate the stage duration of A. steueri in this study area.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제29권1호
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• pp.115-123
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• 1996

For ecological study of Synechogobius hasta the environmental factors, length composition, stages of ovarian maturation, growth, and stomach contents of this species were examined. The samples were collected from the Kum River estuary from May, 1994 to June, 1995. The ovarian egg development of this species underwent 4 stages : the oogonium stage in October to November, growth stage in December to February of next year, maturity stage in February to April, and spawning stage in late April to middle May. The peak spawning period appeared in early to middle May. The fecundity varied from 8,600 to 49,000 showing a exponential increase by body size. The minimum size having matured eggs was 225 mm in total length (standard length 180 mm). The larvae smaller than 10 mm appeared in late May, and young fish of total length $13\~15mm$ entered into bottom life in the shallow waters. The young fish grew rapidly and reached about 141.7 mm in late October. The fish inhabited in the subtidal zone from December to May of next year when began to spawn. The largest specimen examined in this study was 531 mm of male, 472 mm of female. The major food items of young fishes were copepods and invertebrate larvae, and those of adult fishes were crabs, fish, shrimps, cephalopods, and polychaetes.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제30권5호
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• pp.771-781
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• 1997

In order to select an effective and appropriate evaluation method for the marine environmental protection and management, it is necessary to evaluate the present status of environmental conditions and to monitor and regulate the harzadous waste continuously. Among the evaluation methods that use benthic fauna, some graphical methods and biological index methods such as species abundance-biomass (SAB), Rank-frequency diagram (RFD), Abundance-Biomass comparison (ABC), log-normal distribution (LND), and Benthic Pollution Index (BPI) modified by Infaunal Trophic Index were used for the assessments of marine environment in the Inchon coastal area. Even though the graphic methods are convenient for easy glimpse of general trend of environmental condition but because they require sufficient ecological data, those methods do not fit for analysis or comparison of regional and detailed environmental condition. On the other hand, when BPI was applied, it was able to compare the spatial benthic conditions. Through considering the functional aspects of benthic fauna which can not be obtained in the cluster analysis, BPI was made it possible to measure or trace down the source of pollution. In the case of the environmental assessment result analyzed in Inchon coastal area, the north eastern part of Yongjongdo was more influenced by the pollution than the outer area of Inchon. The research indicates that especially Inchon harbor has been greatly affected.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제18권5호
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• pp.477-483
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• 1985

This paper describes seasonal changes of total length, hepatosomatic index (HSI), fatness, egg-diameter composition, and fecundity of the longchin goby Chasmichthys dolichognathus(HILGENDORF). The specimens used were captured in the tide pool of Tongbaekseom, Pusan, Korea from February 1983 to January 1984. The age of longchin goby, tested by size frequency, was believed to be usually one year which grows to 8.0 cm in total length. The annual variations of HSI reached the maximum in the early spring when the gonad was actively growing and decreased during the spawning season from April to July. The coefficients of fatness were represented low values for the spawning periods. Frequency distribution of the egg diameter of mature ovary has three modes: one is the evident mode of the ripe eggs group, and the other two are modes of maturing and immature eggs groups. And an individual is considered as spawns one in the spawning season. Relationships between the fish size in total length (TL cm) and the number of ovarian eggs(F), the fish weight (BW g) and the number of ovarian eggs are indicated by the exponential equation respectively : F=42.585 $TL^{1.608}$, F= 524.589 $BW^{0.475}$.

• The Korean Journal of Malacology
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• 제17권2호
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• pp.71-78
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• 2001

Age and growth of the pen shell, Atrina (Servatrina) pectinata japonica, on the west coast of Korea were studied based on 701 samples caught in April 1995 to March 1996. The results are summarized as follows: the relationship between shell height and ring radius in each ring group was expressed as a regression line. Therefore, it could be recognized that there is a correspondence in the formation of each ring. Based on the monthly variation of the marginal index (MI') of the shell, it was assumed that the ring of this species was formed once a year during the period of June to July. The relationship between shell height (SH) and total weight (TW) were expressed by the following equation TW = 5.906$\times$10/$^{-3}$SH$^{3.844}$. Shell length (SL) and shell height were highly correlated according to the following equation SL = 0.5277 SH +0.0934. The shell height-shell width (SW) relation was expressed by the following equation SW = 0.2681 SH -1.3757. Growth curves for shell height and total weight fitted to the von Bertalanffy's equation were expressed as: SHt=30.99(1-e-$^{-0.3212(t+0.9653)}$, TWt=657.94(1-e-$^{-0.3212(t+0.9653}$)$^{3.3844}$.

• The Korean Journal of Malacology
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• 제19권2호
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• pp.125-132
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• 2003

Age and growth of the the Jedo venus clam, Protothaca jedoensis were investigated using samples from the subtidal zone of Boryeong, Chungcheongnam- do, Korea from January to December, 1999. The relationship between shell height and ring radius in each group was expressed as a regression line. Therefore, it could be recognized that there is a correspondence in the formation of each ring. Based on the monthly variation of the marginal index of the shell, it was suggested that the annual ring mark formation occurred during the period of February to March once a year. The relationship between shell height (SH) and total weight (TW) was represented by the non-linear equation: TW = 0.0007 SH$^{2.8919}$, and also in the relationship between shell length (SL) and shell height (SH), shell height (SH) and shell width (SW) were represented by the linear equations: SL=1.1067SH+1.778, SW=0.6758SH-0.9824. Growth curves for shell height and total weight fitted to the von Bertalanffy equation were expressed as: SH$_t$ = 81.546(1-e$^{-0.176(t+0.381)}$), TW$_t$ = 227.65(1-e$^{-0.176(t+0.381)})^{2.8919}$.

• Microbiology and Biotechnology Letters
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• 제41권3호
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• pp.372-378
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• 2013

An alginate-degrading bacterium, identified as Shewanella oneidensis PKA 1008 by 16S ribosomal RNA sequence analysis, was isolated from the green alga Ulva pertusa. Optimal conditions for the alginate-degrading ability of its crude enzyme were then determined. The optimal culture conditions for the growth of S. oneidensis PKA 1008 were pH 9, 2% NaCl, $30^{\circ}C$, and 24 hours incubation time. The crude enzyme produced by S. oneidensis PKA 1008 showed the highest alginate-degrading activity at pH 9, $30^{\circ}C$ and produced 1.001 g of reducing sugar per liter in 3.5% (w/v) sodium alginate for 1 hour.